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ECE/TRANS/180/Add.16/Amend.2
October 9, 2020
GLOBAL REGISTRY
Created on November 18, 2004, Pursuant to Article 6 of the
AGREEMENT CONCERNING THE ESTABLISHING OF GLOBAL TECHNICAL
REGULATIONS FOR WHEELED VEHICLES, EQUIPMENT AND PARTS WHICH
CAN BE FITTED AND/OR BE USED ON WHEELED VEHICLES
(ECE/TRANS/132 and Corr.1)
DONE AT GENEVA ON JUNE 25, 1998
Addendum 16:
GLOBAL TECHNICAL REGULATION NO. 16
GLOBAL TECHNICAL REGULATION ON TYRES
(ESTABLISHED IN THE GLOBAL REGISTRY ON NOVEMBER 13, 2014)
Incorporating:
Amendment 1 dated March 8, 2017
Amendment 2 dated October 9, 2020

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3.10.
Flat tyre running mode test
3.11.
Rolling sound emission test
3.12.
Adhesion performance on wet surfaces test
3.13.
Rolling resistance test
3.14.
Snow performance test relative to snow tyre for use in severe snow conditions
Annexes
1. Speed symbol table
2. Load index (LI) and equivalent maximum load rating table
3. Nominal rim diameter code table
4. Tyre size designation examples and description
5. Variation of load capacity with speed
6. Tyre-size designations and dimensions
7. Tyre standards organizations
8. Rolling resistance test equipment tolerances
9. Theoretical, measuring, minimum and maximum rim widths and codes
10. Deceleration method - Measurements and data processing for deceleration value applying the
differential form dω/dt
11. Test Equipment Tolerances Specification Guidelines

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Amendment 2
7. Amendment 2 to UN GTR No. 16 addresses the harmonization of the previously non-harmonized
tests applicable to for light truck/commercial (LT/C) tyres, specifically Physical Dimensions Test
and High-speed performance test. The Amendment 2 to UN GTR No. 16 will also cover the most
resent updates of UN Regulation Nos. 30 and 54 as well as FMVSS 139 of the United States.
8. For a complete discussion of Amendment 2 to UN GTR No. 16 see relevant sections of the
Statement of Technical Rationale and Justification.

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B. BACKGROUND OF TYRE REGULATIONS
5. Radial pneumatic tyres for passenger cars and light vehicles are increasingly becoming
worldwide products, expected to be used anywhere in the world when mounted as original
equipment on new vehicles which are themselves marketed on a global basis. This
globalization creates significant opportunities for manufacturers to deliver better and more
cost-efficient products but also requires harmonization of the technical provisions at a global
level to avoid increasing manufacturing costs.
6. Although testing requirements for different regulations used around the world are often
substantially similar, slight variations in test procedures oblige tyre manufacturers to test the
same object for the same performance characteristic under slightly different conditions,
without any significant improvement in the final product.
7. Marking requirements are also variable around the world, and the same tyre may need
several different approval marks to be marketed in a truly worldwide fashion. Any
harmonization of such markings should continue to be a priority, as it would clarify the
administrative identity of the tyre and facilitate the management of production moulds.
C. PROCEDURAL BACKGROUND AND DEVELOPMENT OF THE GLOBAL TECHNICAL
REGULATION
8. UN GTR No. 16 was developed by the former Woirking Party on Brake and Running Gear
(GRRF) informal working group on the Tyre UN GTR.
9. The work on UN GTR No. 16 began informally in December of 2004 with a meeting in Paris.
As required by the 1998 Agreement, a formal proposal for the establishment of a tyre GTR
was proposed to the Executive Committee of the 1998 Agreement (AC.3) by the technical
sponsor, France. At the 140th session of the World Forum for Harmonization of Vehicle
Regulations (WP.29) on November 14, 2006, the French proposal was approved as a GTR
project by AC.3 (ECE/TRANS/WP.29/2006/139). The adopted proposal was published as
ECE/TRANS/WP.29/AC.3/15.
10. Subsequent to that approval, the informal working group on UN GTR No. 16 met on
numerous occasions. In addition to three unofficial meetings held between December 2004
and November 2006, another 10 meetings were scheduled in conjunction with GRRF
sessions and a further two interim meetings were held in Brussels in July 2007 and
July 2009.
11. In 2009, at the request of the informal working group, AC.3 approved the development of
UN GTR No. 16 in two phases: the initial phase being dedicated to harmonizing
requirements for passenger car tyres only, and requirements for light truck tyres, which
carry a C or LT designation, to be harmonized as a second phase. In the interim, the
existing requirements for C or LT tyres (albeit non-harmonized) are included in the first
stage of UN GTR No. 16 for completeness. The current document reflects that decision and
contains only harmonized requirements for passenger car tyres, with the LT/C requirements
remaining to be harmonized.

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17. The tyre industry presented a theoretical method to determine, for each speed symbol, the
test which is the most severe and to validate that the equivalence point (the speed symbol
for which both tests are equally severe) between the two tests is reached at a specific speed
symbol. Over the following year the tyre industry gathered data to demonstrate this concept.
Six tyre manufacturers supplied data, and in total, 704 tyres were tested using both tests. All
the tyres were tested above and beyond the normal high-speed performance test
requirements, and the number of steps that each tyre was able to withstand above the
regulatory limit, were counted. The ratio of the number of Steps above the Limit (SAL) for
the FMVSS 139 test, divided by the number of steps above the limit for UN Regulation
No. 30 test was used to evaluate the data. Based on this extensive set of data, it was
determined that the FMVSS 139 high-speed performance test was more severe for tyres
with speed symbol of S and below (less than or equal to 180km/h). The UN Regulation
No. 30 high-speed performance test was more severe for tyres with speed symbols of T
(190km/h) and above.
18. To validate this concept further, work was undertaken on a smaller sample of tyres to
determine the temperature increase during the different tests. In all cases, it was
demonstrated that for T rated tyres and above, greater energy input was required (as
determined by the increase in the contained air temperature) during the UN Regulation
No. 30 test than from the FMVSS 139 test. This data was also independently confirmed by
one of the Contracting Parties. Since the increase in temperature of a tyre should be directly
related to the amount of energy supplied during the test, a higher internal tyre temperature
at the end of a test indicates a higher degree of severity. At the meeting in September 2008,
it was agreed to use UN Regulation No. 30 test for tyres with speed symbols of T (190km/h)
and above, and to use the FMVSS 139 high-speed performance test for all lower speed
symbols (180km/h and below).
19. The physical dimensions test was less difficult to harmonize from a technical point of view,
because of the elementary simplicity of determining the outside diameter and width of a tyre
in its inflated state to ensure interchangeability between tyres marked with the same size
designation. A small but not insignificant gain has been achieved by harmonizing the
measuring of the tyre's width at four points around the circumference.
20. After the inventory of different tests for passenger car tyres existing in the world had been
made, it appeared that some of these tests might be harmonized on a worldwide level, while
some of them appeared to have a more regional application. In order to take this situation
into account, the different tests were organized into three modules: a mandatory minimum
requirement and two permissive requirements.
21. This modular structure was described in document ECE/TRANS/WP.29/AC.3/15 that was
adopted by AC.3 as the formal request of authorisation to develop UN GTR No. 16.

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23. The initial version of UN GTR No. 16 only provided harmonized requirements for passenger
car tyres. In Amendment 2 to UN GTR No. 16, harmonized requirements were added for
LT/C tyres. The module concept does not apply to LT/C tyres, and the following table
describes the harmonized tests applicable to these tyres following Amendment 2.
Test name
LT/C tyres
Paragraph(s)
Marking and tread wear indicators 3.2., 3.3. and 3.4.
Physical dimensions test 3.5.2.
High-speed test 3.6.2.
Endurance test (not harmonized) 3.9.2.
Wet grip test 3.12.
Run flat test
None
Strength test 3.7.2.
Bead unseating resistance test 3.8.2.
Rolling sound emissions 3.11.
Tyre rolling resistance 3.13.
24. In the case of required markings, it was possible to eliminate some that had become
unnecessary over the years, such as the words Radial and Tubeless. Indeed over 90% of
passenger car tyres and LT/C tyres sold worldwide are of radial, tubeless construction and
so continuing to mark tyres is unnecessary. In addition, a change was made in the way the
Tyre Identification Number (TIN) will be used in combination with other markings.
25. The TIN format is based on NHTSA's 2015 change from 2-digit plant codes to 3 digits. A
symbol, the number "1" for example, will be reserved to precede most existing 2-digit codes,
and be used exclusively for existing plant codes. The "1" is used as the prefix for existing
2-digit codes, and not be used as the leading digit for any new 3-digit codes. NHTSA will
continue to assign global plant codes and the necessary information to obtain such a code
is contained within UN GTR No. 16.
26. The aim of UN GTR No. 16 is to introduce the universal worldwide harmonized
requirements to tyres included into the scope of UN GTR No. 16. In accordance with the
provisions of the 1998 Agreement, once UN GTR No. 16 is adopted, those Contracting
Parties voting in favour of its adoption will start the process of transposing those
requirements into their national legislation. In a case when a test procedure includes several
options, a Contracting Party may select the option(s) at its discretion.
26A. In the interest of moving rapidly towards creating a "global tyre" approach, the Contracting
Parties should transpose UN GTR No. 16 requirements in a flexible way to permit tyres
complying with the full requirements access to as many markets as possible.
27. Consideration was given to harmonize the approval markings (both type approval and
self-certification markings) and discussions on this issue were elevated to WP.29 and AC.3
meetings. It was concluded as not possible currently to adopt a harmonized approval
marking since the compliance assessment procedures are not yet harmonized worldwide.
Consequently, UN GTR No. 16 contains no administrative provisions on approval markings.
In the absence of a harmonized marking, the Contracting Parties retain the option to assign
markings to tyres, especially markings for a "global tyre", and these can be introduced within
their national/regional compliance assessment systems.

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28E. The Amendment 2 to UN GTR No. 16 incorporates:
a.
Amendment of Part I by adding new Paragraphs 49–93;
b.
Amendment of Part II:
i.
Alignment of scope and clarifications;
ii.
Alignment of the provisions with the most recent developments in UN
Regulations;
(a)
(b)
(c)
Addition of new or updated definitions;
Alignment of the provisions for tyre marking;
Alignment of the provisions for tyre physical dimensions;
iii.
Elimination of inconsistencies in the text;
(a)
(b)
Reference Test Inflation Pressure;
Measuring rim;
iv. Updates of Annexes 3, 5, 6, 9 and 11;
v. New Harmonized Provisions;
(a)
(b)
(c)
(d)
Reference test inflation pressure;
Tread wear indicators;
Physical dimensions;
High-speed test;
vi.
vii.
viii.
Amendments reflecting Chinese and Indian proposals;
Others;
Future Work.

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G. SPECIFIC STATEMENT OF TECHNICAL RATIONALE AND JUSTIFICATION FOR
AMENDMENT 1 TO UN GTR NO. 16
1. OBJECTIVE
37. The objective of Amendment 1 is to develop, in the framework of the 1998 Agreement, an
amendment to UN GTR No. 16 on tyres aimed at adaptation of UN GTR No. 16 to the
technical progress by including the newly developed provisions to wet grip performance,
rolling resistance and qualification for use at severe snow conditions both for passenger car
(PC) and light truck/commercial (LT/C) tyres, recently adopted within UN Regulation
No. 117. The approved changes in the relevant Federal Motor Vehicle Safety Standards
(FMVSS) and UN Regulation Nos. 30 and 54 also had been included.
2. INTRODUCTION AND PROCEDURAL BACKGROUND
38. UN GTR No. 16 was established in the Global Registry on November 13, 2014. The
informal working group on UN GTR No. 16 was challenged by reaching harmonization of
technical provisions making those acceptable both for type approval and self-certification
compliance assessment systems.
39. Meanwhile, in parallel to development of UN GTR No. 16, UN Regulation No. 117, which is
one of the bases for UN GTR No. 16, was amended several times by inclusion of the
provisions to tyre wet grip performance, rolling resistance and qualification for use at severe
snow conditions for all tyre classes included in its scope. Other base UN Regulation Nos. 30
and 54 were also subjects to certain amendments, and the relevant provisions of UN GTR
No. 16 needed to be aligned.
40. As harmonization of the newly introduced provisions of UN Regulation No. 117 was not
feasible in a reasonable time frame, the decision for draft UN GTR No. 16 was not to
consider those provisions for inclusion in the text of UN GTR No. 16 at the time of its
development.
41. As the aforesaid new provisions of UN Regulation No. 117, as well as those of UN
Regulation Nos. 30 and 54 represent the state-of-the art level and are important for
assessment of performance of tyres on the markets worldwide, at the 79th GRRF session
the decision was made to prepare a draft amendment keeping UN GTR No. 16 in line with
the latest regulatory developments (ECE/TRANS/WP.29/GRRF/79, Para. 27).
42. The European Tyre and Rim Technical Organisation (ETRTO) agreed to prepare a draft
Amendment No. 1 to UN GTR No. 16 considered as Phase 1b of the development of UN
GTR No. 16. The Government of the Russian Federation assumed the duties of the
technical sponsor for that development.

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H. SPECIFIC STATEMENT OF TECHNICAL RATIONALE AND JUSTIFICATION FOR
AMENDMENT 2 TO UN GTR NO. 16
1. OBJECTIVE
49. The objective of Amendment 2 is to develop, within the framework of the 1998 Agreement,
an amendment to UN GTR No. 16 aimed at further harmonization of its provisions and
updating UN GTR No. 16 to reflect recent amendments to UN Regulations. Amendment 2
also adds new harmonized provisions for physical dimensions and high-speed performance
test for LT/C tyres.
2. INTRODUCTION AND PROCEDURAL BACKGROUND
50. In the initial version of UN GTR No. 16, the harmonized requirements apply only to
passenger car tyres although, as described in Paragraph 23 of this Part, some
non-harmonized tests applicable to LT/C tyres were included in the original UN GTR No. 16.
Amendment 1 was subsequently established in the UN Global Registry on
November 17, 2016, including the newly developed provisions for wet grip performance,
rolling resistance and qualification for use in severe snow conditions both for passenger car
and LT/C tyres.
51. GRRF, at its 82nd session in September 2016, endorsed the establishment (reinstating) of
the Informal Working Group for the Phase 2 of development of UN GTR No. 16 (Tyres)
dealing with development of Amendment 2 to UN GTR No. 16 to harmonize provisions for
LT/C tyres, including marking, high-speed performance test and measuring tyre dimensions.
In addition, the informal working group considered possible further developments of UN
GTR No. 16, including the feasibility of harmonizing of endurance test for LT/C tyres and the
introduction of a global tyre marking. The expert from the Russian Federation volunteered to
lead the development of this amendment and requested the authorization to develop
Amendment 2 to UN GTR No. 16 from the Executive Committee of the 1998 Agreement
(AC.3) (ECE/TRANS/WP.29/GRRF/82, Para. 28).
52. The government of the Russian Federation assumed the duties of the technical sponsor for
that development. The European Tyre and Rim Technical Organisation (ETRTO) in
cooperation with other tyre manufacturers' associations agreed to assume the role of
Secretary in the development of the draft Amendment 2 to UN GTR No. 16.
53. The AC.3 at its 48th session in March 2017 adopted ECE/TRANS/WP.29/2017/52 tabled by
the Russian Federation to request authorization to start work on developing the
Amendment 2 to UN GTR No. 16 (ECE/TRANS/WP.29/1129, Para. 153). After the adoption,
this document was assigned the reference number ECE/TRANS/WP.29/ AC.3/48.
54. At its 175th session in June 2018, The World Forum for Harmonization of Vehicle
Regulations realigned work streams assigned to the various Working Parties. Tyre-related
work under both the 1958 Agreement and the 1998 Agreements was removed from the
GRRF mandate and placed under the Working Party on Noise (GRB) mandate.
Consequently, GRB was renamed to the Working Party of Noise and Tyres (GRBP).
Beginning with the 68th session of the GRBP, tyre-related regulations, including UN GTR
No. 16, were discussed within GRBP. Likewise, the informal working group for UN GTR
No. 16 was moved under GRBP.

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ii.
Alignment of the provisions with the most recent developments in UN Regulations
a. Addition of new or updated definitions
65. The scope of UN GTR No. 16 was amended to add the word "pneumatic" in alignment with
UN Regulation No. 30.
66. Several definitions were amended to reflect amendments to UN Regulation Nos. 30 and
117. The affected definitions included "brand name/trademark", "carcass", "pneumatic",
"normal tyre" and "section width (S)". A definition of "manufacturer" and trade
description/commercial name" was also inserted, consistent with UN Regulation No. 30.
b. Alignment of the provisions for tyre marking
67. Alignment of the provisions for tyre marking of passenger car tyres with the most recent
developments in UN Regulation Nos. 30 and 54 (Sections 2, 3.3 and 3.5).
68. The inscription "M+S", "M.S.", "M&S", "M-S", or "M/S", have been specified as optional if a
tyre is a special use tyre, in line with UN Regulation No. 54.
69. The suffix "LT" after the tyre to rim fitment configuration has been introduced, in line with UN
Regulation No. 54.
c. Alignment of the provisions for tyre physical dimensions
70. The Section width and Outer diameter of the tyre have been aligned with UN Regulation
No. 30.
71. The Section width and Outer diameter of the tyre have been aligned with UN Regulation
No. 54.
iii.
Elimination of inconsistencies in the text
a. Reference Test Inflation Pressure
72. As described in Paragraph 64 above, FMVSS 139 requirements relative to load range and
UN PSI index, strength test and bead unseat test provisions were harmonized to translate
load range into a corresponding reference test inflation pressure.
73. Amendment 2 provides specific reference test inflation pressures for performing the various
prescribed tests. The test prescriptions define a singular test inflation for each reference test
inflation pressure range to ensure common test severity. Therefore, either specifying or
marking (branding) a specific load range (or ply rating) on the tyre is no longer needed. Ply
rating is used to identify a given tyre with its maximum recommended load when used in a
specific type of service. It is an index of tyre strength and does not necessarily represent the
number of cord plies in a tyre. Since some Contracting Parties continue to use the term "ply
rating," the table below is provided for reference to assist Contracting Parties in converting
from ply rating to load range, which can then be converted to reference test inflation
pressure as defined in Section 2.56.

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v. New harmonized provisions
a. Reference test inflation pressure
81. The concept of reference test inflation pressure was introduced to replace the term "PSI
index" used in UN Regulation No. 54, which is a test inflation pressure defined by the tyre
manufacturer. The concept of "PSI index" was inconsistent with the provisions from the
FMVSS 139, which defines inflation pressure in relation to the tyre load carrying capacity.
To harmonize these concepts, reference test inflation pressure was introduced to clearly
define inflation pressure in relation to the maximum load rating. All the references to "PSI
index" in the text have been changed to "Reference Test Inflation Pressure."
b. Tread wear indicators
82. Tread wear indicator provisions have been introduced for LT/C tyres, in line with the
FMVSS 139 requirements.
c. Physical dimensions
83. Physical dimensions provisions were harmonized by deleting the previous Sections 3.20
and 3.21 and adding a new Section 3.5.2. Physical dimensions provisions were also
harmonized by integrating provisions for measuring and calculating physical dimensions and
assuring that all LT/C tyre sizes are addressed by the provisions. Additional provisions were
added to address high flotation sizes.
d. High-speed performance test
84. The high-speed performance test for LT/C tyres was harmonized. The harmonized test
contains two sets of requirements: the first for LT/C tyres with speed symbols below "Q" and
other for LT/C tyres with speed symbols greater than or equal to "Q". The informal working
group concluded that for tyres with speed symbols below "Q" the FMVSS 139 test was the
most severe then developed a modified UN Regulation No. 54 high-speed performance test
that was equivalent to the FMVSS 139 high-speed performance test in terms of test
severity. This modified UN Regulation No. 54 test represents a more efficient test than the
FMVSS 139 high-speed performance test because it is of shorter duration, which impacts
the capacity of testing facilities and reduces testing costs while representing a test that is
comparable in terms of safety. Additionally, eliminating the break-in and cool down cycles
further economizes laboratory resources without affecting test results. The results of the tyre
industry testing programme were accepted by the informal working group without additional
validation by a Contracting Party. For tyres with Speed Symbols "Q" and above the
Amendment 2 of UN GTR No. 16 substituted the non-harmonized provisions of UN
Regulation No. 54 by the new harmonized provisions of the modified load/speed endurance
test method. A provision was also added to recognise a case of a tyre with an alternative
service description, specifying that a second tyre of the same type should be tested
according to the alternative service description unless a clear engineering justification is
made that a single test represents the worst-case combination of load index and speed
category symbol. Consistent with UN Regulation No 54, no provisions were developed for
LT/C tyres with speed symbol above "H".

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Regional markings
Name and number of plies
LT/C Tyres only
"ULT" for mini-type truck tyres
"Regroovable"
Ply rating
Action/Recommendation
Passenger Car Tyres and LT/C Tyres
UN GTR No. 16 does not require a mark indicating the
name and number of plies. A Contracting Party may at
the national level allow an additional optional regional
marking on tyres.
UN GTR No. 16 does not require a mark for "ULT". A
Contracting Party may at the national level allow an
additional optional regional marking on tyres.
LT/C tyres that have a TWI should not be regrooved.
UN GTR No. 16 does not require a mark for ply rating.
For reference, a table converting ply rating to load range
is included in the technical rationale. A Contracting Party
may at the national level allow an additional optional
regional marking on tyres.
vii.
Other Clarifications and Improvements
88. The informal working group did not harmonize the endurance tests for LT/C tyres. The
informal working group streamlined the non-harmonized endurance provisions by presenting
them as two different non-harmonized tests for potential transposition to the
national/regional legislation of the Contracting Parties to the 1998 Agreement. Contracting
Parties may utilize either or both tests for transposition. The first test is based on the
provisions of FMVSS 139, and it is applicable for all LT/C tyres regardless of speed rating.
This option consists of two components: the endurance test and the low inflation pressure
performance test, which must be performed in sequence, using the same tyre and rim
assembly. The second test is based on UN Regulation No. 54 and is applicable only to tyres
with speed symbols below "Q".
89. The informal working group discussed whether to remove the publication year of the ASTM
standards for the various standard reference test tyre (SRTT) standards. The informal
working group agreed to remove the revision years from the ASTM SRTT standards listed in
UN GTR No. 16 but recognized that a Contracting Party may choose to include a revision
year in its national regulations even though it may be difficult or impossible to obtain and
impossible to verify a SRTT from a previous revision year. The informal working group
reviewed the detailed and rigorous quality assurance and control measures in place to
assure that SRTT performance remains consistent. The validation process includes
validation of both the tread rubber and the finished tyre. The tread rubber is validated by
testing samples in both the manufacturer's laboratory and an independent laboratory to
assure material properties. Tyre quality and performance are validated by taking a random
sample of 10 tyres from each build and subjecting them to physical and chemical
measurements and a range of tyre performance tests, including both regulatory and
proprietary tests. In addition, the informal working group noted that the revision year is not
included on the sidewall of any SRTT. The informal working group recognized a distinction
between listing the revision year for an SRTT standard and listing a revision year for a tyre
testing standard, where substantive provisions may change from revision to revision.

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II.
TEXT OF THE GLOBAL TECHNICAL REGULATION
1. SCOPE
1.1. This Global Technical Regulation covers new radial pneumatic tyres referred to
as 'tyres' in this document designed primarily for vehicles in Categories 1 and 2,
all with a gross vehicle mass of 4,536kg or less, as defined in the Special
Resolution No. 1.
1.2. This global technical regulation does not apply to:
(a)
(b)
(c)
(d)
(e)
T-Type temporary use spare tyres;
Tyres having a nominal rim diameter code ≤8 (or ≤203mm).
Special Tyres (ST) for trailers in highway service;
LT or C tyres with tread-depth of greater than or equal to 14.3mm
(18/32in);
Class C3 tyres except those with Load Index between 122 and 131 that
contain "LT" or "C" in the size designation.
1.3. The definitions for the different kinds of tyres are provided in Section 2 of this
regulation.
2. DEFINITIONS
For the purpose of this Regulation the following definitions apply:
2.1. "Acceleration test" means a series of specified number of traction-controlled
acceleration test runs of the same tyre repeated within a short timeframe;
2.2. "Adhesion on wet surfaces" means the relative braking performance, on a wet
surface, of a test vehicle equipped with the candidate tyre in comparison to that
of the same test vehicle with a Standard Reference Test Tyre (SRTT);
2.3. "Metric-A tyre" or "Metric-U tyre" means a Metric tyre with a "A" or "U" suffix
indicating a passenger car tyre intended to be used on specific rims; refer to
Annex 4 for examples;
2.4. "Basic tyre functions" means the nominal capability of an inflated tyre in
supporting a given load up to a given speed and transmitting the driving, the
steering and the braking forces to the ground on which it runs;
2.5. "Bead" means the part of the tyre which is of such shape and structure as to fit
the wheel rim and hold the tyre on it;
2.6. "Bead separation" means a breakdown of the bond between components in the
tyre bead area;

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2.23. "Cracking" means any parting within the tread, sidewall or inner liner of the tyre
which may or may not extend to cord material;
2.24. "Deflected section height" is the difference between the deflected radius,
measured from the centre of the rim to the surface of the drum, and one half the
nominal rim diameter as defined in ISO 4000-1:2010;
2.25. "Extra Load" means a tyre structure designed to carry more load at a higher
inflation pressure than the load carried by the corresponding standard version
tyre at the standard inflation pressure as specified in ISO 4000-1:2010;
2.26. "Flat tyre running mode" describes the state of the tyre, essentially maintaining
its structural integrity, while operating at an inflation pressure between 0 and
70kPa, for runflat tyres or systems;
2.27. "High flotation tyre" means an LT/C tyre which is dimensionally larger and
operates at a lower inflation pressure than the tyre it replaces to provide
improved flotation in off-the-road service. Refer to Annex 4 for examples;
2.28. "Inner liner" means the layer of rubber forming the inside surface of a tubeless
tyre that contains the inflating medium within the tyre;
2.29. "Inertia or Moment of Inertia" means the ratio of the torque applied to a
rotating body to the rotational acceleration of this body ;
2.30. "Intended outboard sidewall" means the sidewall that contains a whitewall,
bears white lettering, or bears manufacturer or model name moulding that is
higher or deeper than that on the other sidewall of the tyre;
2.31. "Laboratory Control Tyre" means the tyre used by an individual laboratory to
control machine behaviour as a function of time;
2.32. "Light Load tyre (LL)" means a tyre designed for loads lower than the standard
load (SL) version;
2.33. "Light truck or commercial tyre" also referred to as "LT/C tyres" in this
document, means a tyre of a group prescribed in the "LT" Light Truck or "C-type"
Commercial or "CP-type" Commercial tyre section of the standards manuals of
the organizations shown in Annex 7; Refer to Annex 4 for examples;
2.34. "Load index" means a numerical code which indicates the maximum load
rating. The list of these indices and their corresponding reference loads is given
in Annex 2;
2.35. "Load capacity" means the maximum load that a tyre is able to carry subject to
the tyre operating speed, the tyre speed symbol and the tyre class. Annex 5
specifies the Tyre Load Capacity variation for Class C1 (Passenger Car) and
Class C2 or Class C3 (LT/C) tyres;

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2.43. "Measuring rim width" means a particular rim width as defined in Annex 9,
except for the sizes listed in Annex 6, where the measuring rim width is obtained
by multiplying the measuring rim width code indicated in the table by 25.4;
2.44. "Metric tyre" means a tyre which has its nominal section width denomination
expressed in mm and the aspect ratio expressed as a percentage or the outer
diameter expressed in mm as part of the size designation. Refer to Annex 4 for
examples;
2.45. "Minimum and maximum rim widths" define a range of rim widths to which the
tyre can be fitted for testing, as specified for the relevant tests;
2.46. "Nominal aspect ratio (profile)" means the ratio of the nominal section height
to the nominal section width expressed as a percentage in a multiple of 5 (ending
in 0 or 5);
2.47. "Nominal section width" is a theoretical standardised section width, which is
part of the tyre size designation. The nominal section width of the tyre shall be
indicated in millimeters (mm) except in the case of high flotation tyres. In the
case of High flotation sizes, it is expressed by a code that will end in « .50 » and
its value is given in mm and is obtained by multiplying the code by 25.4 and
rounded as indicated in the Table 3 in Paragraph 3.5.2.2.1. For the existing
types of tyres whose designation is given in the first column of the tables in
Annex 6 to this regulation, the nominal section width shall be deemed to be that
given opposite the tyre designation in those tables;
2.48. "Normal tyre" means a tyre intended for normal on-road use;
2.49. "Open splice" means any parting at any junction of tread, sidewall, or inner liner
that extends to cord material;
2.50. "Outer diameter" means the overall diameter of an inflated new tyre;
2.51. "Overall width" means the linear distance between the outsides of the sidewalls
of an inflated tyre, including elevations due to labelling (marking), decorations,
and/or protective bands or ribs;
2.52. "Parasitic loss" means loss of energy (or energy consumed) per unit distance
excluding internal tyre losses, attributable to aerodynamic loss of the different
rotating elements of the test equipment, bearing friction and other sources of
systematic loss which may be inherent in the measurement;
2.53. "Passenger car tyre" means a tyre of a group prescribed in the passenger car
tyre section of the standards manuals from one of the organizations shown in
Annex 7;
2.54. "Peak brake force coefficient ("pbfc")" means the maximum value of a tyre
braking force coefficient that occurs prior to wheel lockup as the braking torque is
progressively increased.
2.55. "Ply" means a layer of rubber-coated parallel cords;
2.56. "Ply separation" means a parting of adjacent plies;

---

2.65. "Rolling resistance coefficient Cr" means the ratio of the rolling resistance to
the load on the tyre ;
2.66. "Rolling resistance Fr" means the loss of energy (or energy consumed) per
unit of distance traveled ;
2.67. "Run flat tyre" or "Self-supporting tyre" describes a tyre structure provided
with any technical solutions (for example, reinforced sidewalls, etc.) allowing the
tyre, mounted on the appropriate wheel and in the absence of any
supplementary component, to supply the vehicle with the basic tyre functions, at
least, at a speed of 80km/h (50mph) and a distance of 80km when operating in
flat tyre running mode;
2.68. "Run flat system" or "Extended mobility system" describes an assembly or
specified functionally dependant components, including a tyre, which together
provide the specified performance granting conditions for the vehicle with at least
basic tyre functions, at a speed of 80km/h (50mph) and a distance of 80km
(50mi) when operating in flat tyre running mode;
2.69. "Secondary grooves" means the supplementary grooves of the tread pattern
which may disappear in the course of the tyre's life;
2.70. "Section height" means a distance equal to half the difference between the
outer diameter of the tyre and the nominal rim diameter;
2.71. "Section width" means the linear distance between the outside of the sidewalls
of an inflated tyre, excluding elevations due to labelling (marking), decoration or
protective band or ribs;
2.72. "Service description" means the association of the load index or indices with a
speed symbol (for example, 91H or 121/119S);
The service description of an LT/C tyre may include either one or two load
indices which indicate the load the tyre can carry in single or in single and dual
operation. In addition, an LT/C tyre can have an alternative service description;
2.73. "Sidewall" means that portion of a tyre between the tread and the bead;
2.74. "Sidewall separation" means the parting of the rubber compound from the cord
material in the sidewall;
2.75. "Skim test reading" means the type of parasitic loss measurement, in which the
tyre is kept rolling without slippage, while reducing the tyre load to a level at
which energy loss within the tyre itself is virtually zero;
2.76. "Snow grip index (SG)" means the ratio between the performance of the
candidate tyre and the performance of the standard reference test tyre;
.

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2.86. "Temporary use spare tyre" means a tyre different from a tyre fitted to a
vehicle for normal driving conditions, and intended only for temporary use under
restricted driving conditions;
2.87. "Test rim" means the rim on which a tyre is fitted for testing;
2.88. "Test run" means a single pass of a loaded tyre over a given test track surface;
2.89. "Test tyre(s)" means a candidate tyre, a reference tyre or a control tyre or tyre
set that is used in a test run;
2.90. "Theoretical rim width" means a rim width specified in Annex 9 and used to
determine the tyre physical dimensions. The theoretical rim width is expressed in
mm;
2.91. "Spin Traction test" means a series of a specified number of spin-traction test
runs according to ASTM standard F1805-06 of the same tyre repeated within a
short time frame;
2.92. "Traction tyre" means a tyre in Class C2 or C3 bearing the inscription
TRACTION and intended to be fitted primarily to the drive axle(s) of a vehicle to
maximize force transmission in various circumstances;
In order to be classified as a "traction tyre", a tyre is required to meet at least one
of the following conditions:
The tyre shall have a tread pattern with minimum two circumferential ribs, each
containing a minimum of 30 block-like elements, separated by grooves and/or
sipe elements the depth of which has to be minimum of one half of the tread
depth.
2.93. "Trade description/commercial name" means an identification of a range of
tyres as given by the tyre manufacturer. It may coincide with the brand
name/trademark;
2.94. "Tread" means that part of a tyre that comes into contact with the road;
2.95. "Tread pattern groove" means the space between two adjacent ribs or blocks
in the tread pattern;
2.96. "Tread depth" means the depth of the principal grooves;
2.97. "Tread pattern" means the geometric arrangement of blocks, ribs and grooves
of the tread;
2.98. "Tread separation" means the pulling away of the tread from the tyre carcass;
2.99. "Tread Wear Indicators (TWI)" means the projections within the principal
grooves designed to give a visual indication of the wear of the tread;
2.100. "Tubeless tyre" means a tyre specifically designed for fitting to appropriate
wheel rims without an inner tube;

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3.1.1.4. The name, or other identifying designation, of each individual plant operated by
the manufacturer and the address of each plant, if applicable;
3.1.1.5. The type of tyres manufactured at each plant, e.g., tyres for passenger cars,
buses, trucks or motorcycles; pneumatic retreaded tyres; or non-pneumatic
retreaded tyres; or non-pneumatic tyre assemblies.
3.1.2. Plant Code for Manufacturers with no Specified Representative in the United
States of America
3.1.2.1. The plant code for tyres manufactured by companies with no specified
representative in the United States of America will be 999.
3.2. Marking
3.2.1. The Tyre Identification Number is a series of numbers, letters and spaces in the
format YYY_MMMMMM_DDDD.
3.2.1.1. The YYY is a 3-digit universal plant code for the place of manufacture of the tyre.
3.2.1.2. The MMMMMM is a 6-digit manufacturer's code. Within the tyre identification
number format, this will be an 6-digit required field, but the content is up to the
tyre manufacturer.
3.2.1.3. The DDDD with 4 digits represents the week and year of manufacture, also
known as the date code. The first two symbols shall identify the week of the year
by using "01" for the first full calendar week in each year, "02" for the second full
calendar week, and so on. The calendar week runs from Sunday through the
following Saturday. The final week of each year shall include not more than
6 days of the following year. The third and fourth symbols shall identify the year.
Example: 0110 means the first week of 2010.
3.2.1.4. The Tyre Identification Number shall be located on the intended outboard
sidewall of the tyre and positioned between the bead and 50% of the distance
from the bead to the tread. On the other sidewall of the tyre either a tyre
identification number or a partial tyre identification number is required. The
partial tyre identification number is comprised of all characters except the date
code. If the tyre has no intended outboard sidewall, the complete tyre
identification number shall be placed on one sidewall, and a partial or complete
tyre identification number shall be placed on the other sidewall.
3.2.1.5. The symbols to be used in the tyre identification number format are A, B, C, D, E,
F, H, J, K, L, M, N, P, R, T, U, V, W, X, Y, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0.
3.2.1.6. The symbols that shall not be used are G, I, O, Q, S, and Z.
3.2.1.7. The font to be used for the Tyre Identification Number shall be Futura Bold,
Modified Condensed, Gothic, or OCR-B (as defined in ISO 1073-2: 1976).
3.2.1.8. The characters shall have a height of at least 6mm and a positive or negative
relief of between 0.5 to 1.0mm, as measured from the surface in the immediate
vicinity of the marking.

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3.3.3. For tyres suitable for speed in excess of 300km/h, the Letter "R" placed in front
of the rim diameter code symbol marking shall be replaced by "ZR" and the tyre
shall be marked, in parentheses, with a service description consisting of the
speed symbol "Y" and a corresponding load index, for example, 245/45ZR17
(95 Y).
Note: The maximum speed permitted by the tyre manufacturer and the
corresponding load capacity for that maximum speed shall be stated in
the tyre manufacturer's technical literature and made available to the
public.
3.3.4. For passenger car tyres, each tyre shall be labelled with its maximum
permissible inflation pressure in kPa (psi) and shall be labelled with its maximum
load rating in kg (lbs).
3.3.5. In the case of LT/C tyres, the maximum load rating and corresponding inflation
pressure of the tyre, shown as follows:
"Max load single ___kg (___lb) at ___kPa (___psi) cold
"Max load dual ___kg (___lb) at ___kPa (___psi) cold".
For LT/C tyres rated for single fitment only, mark as follows:
"Max load single___kg (___lb) at ___kPa (___psi) cold".
The inflation pressure marked for single application shall be taken as the
Reference Test Inflation Pressure, unless a different value for the Reference
Test Inflation Pressure is marked separately as follows :
"Max load single ___kg (___lb) at ___kPa (___psi) cold
Max load dual ___kg (___lb) at ___kPa (___psi) cold.
TEST AT: ___kPa"
For LT/C tyres rated for single fitment only, mark as follows:
"Max load single ___kg (___lb) at ___kPa (___psi) cold
TEST AT: ___kPa"
When implementing this paragraph, the Contracting Parties may limit the
difference between the inflation pressure(s) marked for single application (and
dual application if applicable) and the Reference Test Inflation Pressure.

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3.3.12. In the case of LT or C type tyres, the inscription "ET" or "ML" or "MPT" and/or
"POR" for "Special use tyres":
3.3.12.1. ET = Extra Tread;
3.3.12.2. ML = Mining and Logging tyre used in intermittent highway service;
3.3.12.3. MPT = Multi-purpose Truck tyres;
3.3.12.4. POR = Professional Off-road tyres.
3.3.12.5. In addition, they may also bear the inscription M+S or M.S or M&S.
3.3.13. In the case of LT or C tyres, the prefix "LT" before the tyre size designation, or
the suffix "C" or "LT" after the rim diameter marking referred to in Annex 3, and, if
applicable, after the tyre to rim fitment configuration referred to in
Paragraph 3.3.1.2.3.3. or the suffix "LT" after the service description
3.3.14. In the case of CP tyres as defined in 2.22, the suffix "CP" replaces the suffix "C"
after the rim diameter marking referred to in Annex 3 and, if applicable, after the
tyre to rim fitment configuration referred to in Paragraph 3.3.1.2.3.3. This
marking is mandatory in the case of tyres fitted on 5° drop centre rims, having a
load index in single operation lower or equal to 121 and specifically designed for
the equipment of motor caravans.
3.4. Tread Wear Indicators
3.4.1. Except as noted below, each passenger tyre and each LT/C tyre shall have at
least six transverse rows of tread wear indicators, approximately equally spaced
around the circumference of the tyre and situated in the principal grooves of the
tread.
3.4.2. For passenger car tyres designed for mounting on rims of nominal rim diameter
code 12 or less, not less than three transverse rows of tread wear indicators is
acceptable.
3.4.3. The tread wear indicators may be identified by the acronym 'TWI', or by means
of a triangle, or by an arrow radially arranged on the tyre, or else by a symbol
determined by the manufacturer. These indications may be moulded on both
sides of the sidewall in the tyre shoulder region.
3.4.4. The height of each tread wear indicator shall be 1.6 mm.

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3.5.1.1.2. Outer Diameter of Tyre
The outer diameter of the tyre shall be calculated by the following formula:
D = d + 2 • H
Where:
D
d
H
is the outer diameter in millimetres,
is the nominal rim diameter as defined in the Nominal rim diameter code
table in Annex 3.
is the nominal section height rounded to the nearest millimeter and is equal
to:
H = S • 0.01 Ra, where
S
is the nominal section width in millimeters;
Ra is the nominal aspect ratio;
3.5.1.1.2.1. However, for the existing types of tyres whose designation is given in the first
column of the tables in Annex 6 to this regulation, the outer diameter shall be
deemed to be that given opposite the tyre designation in those tables.
3.5.1.1.2.2. However, for metric-A or metric-U tyres, the outer diameter shall be that
specified in the tyre size designation as shown on the sidewall of the tyre.
3.5.1.2. Physical Dimensions Measurement Method
3.5.1.2.1. Mount the tyre on a test rim with a width comprised between the minimum and
maximum width as per Annex 9.
3.5.1.2.2. Adjust the pressure to that specified in the table below:
Table 2
Physical Dimensions Test Inflation Pressures
Tyre application
Test inflation pressure (kPa)
Standard load, light load 180
Extra load 220
3.5.1.2.3. Condition the tyre, mounted on its rim, at the ambient room temperature between
18°C and 38°C for not less than 24h.
3.5.1.2.4. Readjust the pressure to that specified in the table above.

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Where the coefficients "a" and "b" are:
coefficient "a" = 0.97
coefficient "b" = 1.04 for normal tyres and 1.06 for special-use tyres
For snow tyres the outer diameter shall not exceed the following value
D = 1.01 • D rounded to the nearest mm
where D is the maximum outer diameter established for the normal tyres in
conformity with the above.
3.5.1.3.2.2. However, for the types of tyres whose size designation is given in the first
column of the tables in Annex 6 to this regulation, and for metric-A or metric-U
tyres, the nominal section height H is equal to:
H = 0.5 • (D − d), rounded to the nearest millimeter – for references see
Paragraph. 3.5.1.1.2.;
3.5.1.4. Figure 1: Drawing of normal tyre showing rim diameter (d), outside diameter (D),
section height (H) and section width (S) and the rim width (A).
Figure 1
Drawing of a Normal Tyre Showing Various Dimensions
3.5.1.5. For other tyre sizes for which dimensions cannot be calculated, the dimensions
including allowance for growth in service, shall comply with those given in
standards publications of the organizations listed in Annex 7 and which were
current either at the date of manufacture of the tyre or at any later date.

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3.5.2.2. Reference Dimensions for High Flotation Sizes (excluding all sizes listed in
Annex 6)
For a description of the high flotation size designation, see example in Annex 4.
To convert dimensions expressed in code to mm, multiply the code by 25.4 and
round to the nearest mm.
3.5.2.2.1. Section Width of a Tyre
The tyre section width is calculated by adjusting the section width value for the
measuring rim widths from the table below by 5mm for each 0.5 change in test
rim width code vs the measuring rim width code.
The tyre section widths for the measuring rim widths as specified in
Paragraph 2.2 of Annex 9 are as follows:
Nominal Section Width
code
Table 3
Tyre Section Width
Measuring Rim Width
Code
Tyre Section Width (mm)
7.50 6.00 191
8.50 7.00 218
9.50 7.50 240
10.50 8.50 268
11.50 9.00 290
12.50 10.00 318
13.50 11.00 345
14.50 11.50 367
15.50 12.50 395
16.50 13.00 417
17.50 14.00 445
18.50 15.00 472
19.50 15.50 496

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3.5.2.4.7. Determine the height of the tread wear indicators by measuring the difference
between the total depth of the tread pattern groove in the vicinity of the tread
wear indicator and the depth to the top of the tread wear indicator. Repeat this
measurement for at least one tread wear indicator in each row (minimum of 6 or
3, depending on the rim diameter; a row is the linear sequence of tread wear
indicators positioned radially across the tread from one side to the other). At
least one tread wear indicator in each principal groove shall be measured (the
principal grooves are the wide grooves positioned circumferentially around the
tread). Record all of the individual values rounded to the nearest tenth of a
millimeter.
3.5.2.5. Physical Dimension Requirements
3.5.2.5.1. Metric Tyre Sizes (excluding all sizes listed in Annex 6)
3.5.2.5.1.1. Overall Width
3.5.2.5.1.1.1. The overall width of a tyre may be less than the section width or widths
determined pursuant to Paragraph 3.5.2.1.2. above.
3.5.2.5.1.1.2. It may exceed that value by 4%. The respective limits shall be rounded to the
nearest millimeter (mm).
3.5.2.5.1.1.2.1. However, for LT/C tyres belonging to a group prescribed in the "C-type"
commercial or "CP-type" commercial tyre sections of the ETRTO Standards
Manual or in the sections "B" or "S" of the JATMA Year Book, tyres with nominal
section width exceeding 305mm and aspect ratio higher than 60 designed for
dual mounting (twinning), the overall width of the tyre may exceed the value
determined pursuant to Paragraph 3.5.2.1.2. by 2%. The respective limits shall
be rounded to the nearest millimeter (mm).
This paragraph does not apply to tyres included by the other tyre standards
organisations listed in Annex 7 of this regulation.
3.5.2.5.1.1.3. However, for metric-A tyres, the overall width of the tyre, in the lower area of the
tyre, equals the nominal width of the rim on which the tyre is mounted, as shown
by the manufacturer in the descriptive note, increased by 27mm.
3.5.2.5.1.2. Outer Diameter
3.5.2.5.1.2.1. The outer diameter of a tyre shall not be outside the range Dmin and Dmax
obtained from the following formulae:
Dmin = d + (2 • Hmin)
Dmax = d + (2 • Hmax)
Where
Hmin = H • a, rounded to the nearest mm
Hmax = H • b, rounded to the nearest mm
"H" and "d" are as defined in Paragraph. 3.5.2.1.3.1.

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3.5.2.5.3. Sizes Listed in Annex 6
3.5.2.5.3.1. Overall Width
3.5.2.5.3.1.1. The overall width of a tyre may be less than the section width as pursuant to
Paragraph 3.5.2.2.1. The overall width may exceed the section width pursuant to
Paragraph 3.5.2.2.1. as follows:
3.5.2.5.3.2. Outer Diameter
For tyre sizes listed in Tables A6/1, A6/2 and A6/3 – by up to 4%
For tyre sizes listed in Table A6/4 – by up to 8%.
For tyre sizes listed in Table A6/5 – by up to 7%.
The respective limits shall be rounded to the nearest millimeter (mm).
3.5.2.5.3.2.1. The outer diameter of a tyre shall not be outside the range Dmin and Dmax
obtained from the following formulae:
Dmin = d + (2 • Hmin)
Dmax = d + (2 • Hmax)
Where
Hmin = H • a, rounded to the nearest mm
Hmax = H • b, rounded to the nearest mm
H = 0.5 • (D − d) rounded to the nearest mm;
D
d
is the outer diameter given opposite the tyre size designation in the tables
of Annex 6.
is the nominal rim diameter (mm) given opposite the tyre size designation
in the tables of Annex 6.
Coefficient 'a' for the calculation of Hmin:
Coefficient "b" for the calculation of Hmax:
a = 0.97
For tyre sizes listed in Tables A6/1, A6/2 and A6/3:
For normal tyres, b = 1.04
For snow tyres the outer diameter shall not exceed the following value: Dmax,
snow = 1.01 • Dmax, rounded to the nearest mm, where Dmax is the maximum
outer diameter established for normal tyres above.

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3.6.1.2. Preparation of the tyres with speed symbols "F" to "S" as specified in Annex 1 to
this regulation.
3.6.1.2.1. Mount the tyre on a test rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre. Inflate it to the appropriate pressure specified in
the table below:
Table 4
Inflation Pressure and Test Load
Speed symbol
F, G, J, K L, M, N, P,
Q, R, S
Inflation pressure, kPa
Standard load
tyres, light load
tyres
Extra load tyres
220 260
Test load
85%
of the maximum load
rating
3.6.1.2.2. Condition the assembly at (35 ± 3)°C for not less than 3h.
3.6.1.2.3. Before or after mounting the assembly on a test axle, readjust the tyre pressure
to that specified in the table above in Paragraph 3.6.1.2.1.
3.6.1.3. Test procedure for tyres with speed symbols "F", "G", "J", "K", "L", "M", "N", "P",
"Q", "R" or "S" as specified in Annex 1
3.6.1.3.1. Press the assembly against the outer face of a test drum having a diameter of
1.7m ± 1% or 2.0m ± 1% and surface at least as wide as tyre tread.
3.6.1.3.2. Apply to the test axle a load equal to 85% of the maximum load rating.
3.6.1.3.3. Break-in the tyre by running it for 2h at 80km/h.
3.6.1.3.4. Allow the tyre to cool to 38°C and readjust inflation pressure to the applicable
pressure in the table in Paragraph 3.6.1.2.1. above immediately before the test.
3.6.1.3.5. Throughout the test, the inflation pressure is not corrected, and the test load is
maintained at the value applied in Paragraph 3.6.1.2.1.
3.6.1.3.6. During the test, the ambient temperature, shall be maintained at (35 ± 3)°C.
The measurement equipment for ambient temperature shall be placed in a
location between 150mm and 1,000mm away from the test tyres.

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3.6.1.5.5. Carry the test through, without interruptions as follows, in relation to the tyre's
speed symbol.
3.6.1.5.6. The initial test speed (ITS) is equal to the tyre's speed symbol:
(a)
(b)
Less 40km/h on a 1.7m ± 1% drum, or
Less 30km/h on a 2.0m ± 1% drum.
3.6.1.6. For tyres of speed symbols "T" to "W" as specified in Annex 1;
3.6.1.6.1. Accelerate the equipment at a constant rate such that the initial test speed (ITS)
is reached at the end of 10min from start-up.
(a)
(b)
(c)
(d)
Then, at the ITS for 10min;
Then, at the ITS plus 10km/h for 10min;
Then, at the ITS plus 20km/h for 10min;
Then, at the ITS plus 30km/h for 20min.
3.6.1.6.2. For tyres of speed symbol "Y": Accelerate the equipment at a constant rate such
that the Initial Test Speed (ITS) is reached at the end of 10min from start-up.
(a)
(b)
(c)
(d)
Then, at the ITS for 20min;
Then, at the ITS plus 10km/h for 10min.
Then, at the ITS plus 20km/h for 10min;
Then, at the ITS plus 30km/h for 10min.
3.6.1.7. For tyres with "ZR" in the size designation intended for use at speeds greater
than 300km/h;
3.6.1.7.1. Test the tyre at the load and inflation for a speed symbol "Y" tyre according to
the procedures specified above in Paragraphs 3.6.1.4.2. and 3.6.1.6.2. above.
3.6.1.7.2. Test a further sample of the same type according to:
Inflate the tyre to 320kPa for standard load or light load tyres and 360kPa for
extra load tyres. Apply a load to the test axle that is equal to 80% of the
maximum load rating specified by the tyre manufacturer. Accelerate the
equipment at a constant rate such that the rated speed of the tyre is reached at
the end of 10min from the start-up. Then test at the rated speed for 5min.

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3.6.2.1.3.4. Allow tyre to cool to 38°C and readjust inflation pressure to applicable pressure
in Paragraph 3.6.2.1.2.1. immediately before the test.
3.6.2.1.3.5. Throughout the test, the inflation pressure is not corrected, and the test load is
maintained at the value applied in Paragraph 3.6.2.1.2.1.
3.6.2.1.3.6. During the test, the ambient temperature, is maintained at (35 ± 3)°C. The
measurement equipment for ambient temperature shall be placed in a location
between 150mm and 1,000mm away from the test tyres.
3.6.2.1.3.7. The test is conducted, continuously and uninterrupted, for 90min through three
30min consecutive test stages at the following speeds: 140, 150, and 160km/h.
3.6.2.1.3.8. Allow the tyre to cool for between 15min and 25min. Measure its inflation
pressure. Then, deflate the tyre, remove it from the test rim, and inspect it for the
conditions specified in Paragraph 3.6.2.1.1.1., Subparagraph (a).
3.6.2.2. High Speed Performance Test for LT/C Tyres with Speed Symbol ≥ "Q"
3.6.2.2.1. Requirements
3.6.2.2.1.1. When the tyre is tested in accordance with Paragraph 3.6.2.2.3.:
(a)
(b)
There shall be no visual evidence of any tread separation, ply separation,
cord separation, chunking or broken cords;
The outer diameter of the tyre, measured 6h after the test, shall not differ
by more than ±3.5% from the outer diameter as measured before the test.
3.6.2.2.1.2. If the load/speed combination for the tyre is given in the table in Annex 5
"Variation of load capacity with speed for LT/C tyres", the test prescribed in
Paragraph 3.6.2.2. need not be carried out for load and speed values other than
the nominal values.
3.6.2.2.1.3. In the case of a tyre which has an alternative Service Description in addition to
the one that is subject to the variation of load with speed given in the table in
Annex 5 to this Regulation, the test prescribed in Paragraph 3.6.2.2. shall also
be carried out on a second tyre of the same type at the additional load/speed
combination, unless a sufficient engineering justification is provided by the tyre
manufacturer for a worst-case combination of load index and speed category
symbol, to be tested.
3.6.2.2.2. Preparation of Tyre
3.6.2.2.2.1. Mount the tyre on a test rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre.
3.6.2.2.2.2. Use a new inner tube or combination of inner tube, valve and flap (as required)
when testing tyres with inner tubes.
3.6.2.2.2.3. Inflate the tyre to the Reference Test Inflation Pressure.

---

3.6.2.2.7. Final test speed: speed corresponding to the speed symbol:
3.6.2.2.7.1. Duration of the final step = 30min.
3.7. Strength Test
3.7.1. Strength Test for Passenger Car Tyres
3.7.1.1. Each tyre shall meet the requirements for minimum breaking energy as
calculated in 3.7.1.2.6. specified in the table below.
Table 8
Minimum Breaking Energy
Nominal section
width
Below 160mm
160mm or above
Units
Standard load or
light load tyres
Extra load tyres
Joules 220 441
Inch-pounds 1,950 3,900
Joules 294 588
Inch-pounds 2,600 5,200
3.7.1.2. Strength Test Procedure
3.7.1.2.1. Mount the tyre on a test rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre. Inflate it to the test inflation pressure specified in
the table below:
Table 9
Strength Test Tyre Inflation Pressures for Strength Test
Tyre application
Test Inflation pressure
(kPa)
Standard load, light load 180
Extra load 220
3.7.1.2.2. Condition the wheel and tyre assembly for at least 3h at the temperature of the
test room;
3.7.1.2.3. Re-adjust the tyre pressure to that specified in the previous table above
(Paragraph 3.7.1.2.1.);
3.7.1.2.4. Force a (19 ±0.5)mm ((0.75 ± 0.02)in) diameter cylindrical steel plunger with a
hemispherical end perpendicularly into the tread rib as near to the centreline as
possible, avoiding penetration into the tread pattern groove, at the rate of
(50 ± 2.5)mm/min ((2 ± 0.1)in/min).

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3.7.2. Strength Test for LT/C Tyres
3.7.2.1. Requirements
When tested according to the procedure described in this section, LT/C tyres
shall have an average strength as calculated in 3.7.2.3.3 of not less than the
values shown in the table below:
Reference Test
Inflation
Pressure
Range (kPa)
3.7.2.2. Preparation of Tyre
Table 10
Minimum Strength
Rim Diameter Codes > 13
Tubeless
Rim Diameter Codes > 15 Tube
Type
Nominal Section Width
≤ 295mm
> 295mm
Rim Diameter
Codes < 12
Tubeless and
Tube Type
Rim Diameter
Codes 13 and
14
Tube Type
170 – 199 n/a 294 68 n/a
200 – 299 294 362 136 192
300 – 399 362 514 203 271
400 – 499 514 576 271 384
500 – 599 576 n/a 339 514
Mount the tyre on a rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre.
Inflate it to the Reference Test Inflation Pressure.
If the tyre is tubeless, a tube may be inserted to prevent loss of air during the test
in the event of puncture
Condition it at ambient room temperature for at least 3h and readjust the inflation
pressure if necessary.

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3.8.1.1.2. For tubeless radial ply tyres the applied force required to unseat the tyre bead at
the point of contact, in relation to the nominal section width of the tyre, shall not
be less than:
Table 11
Minimum Bead Unseating Force (Metric Tyre Sizes)
Nominal section width
(mm)
Minimum force
(N)
Less than 160 6,670
From 160 to 204 8,890
Equal to or greater than 205 11,120
Table 12
Minimum Bead Unseating Force (Other Tyre Sizes)
Nominal section width
(code)
Minimum force
(N)
Less than 6.00 6,670
From 6.00 to 7.99 8,890
Equal to or greater than 8.00 11,120
3.8.1.2. Preparation of Tyre
3.8.1.2.1. Wash the tyre and dry it at the beads. Mount it without lubricant or adhesive on a
clean, painted test rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre.
3.8.1.2.2. Inflate the tyre to the pressure specified in the Table shown below:
Table 13
Test Inflation Pressures for Bead Unseating Resistance Test
Tyre application
Test inflation pressure
kPa
Standard load, light load 180
Extra load 220

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Table 14
List of "A" Dimensions
Table of A dimension for different rim codes
Rim code
mm
Inches
20
345
13.50
19
330
13.00
18
318
12.50
17
305
12.00
16
292
11.50
15
279
11.00
14
267
10.50
13
254
10.00
12
241
9.50
11
229
9.00
10
216
8.50
320
216
8.50
340
229
9.00
345
235
9.25
365
248
9.75
370
254
10.00
390
279
11.00
415
292
11.50

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Figure 4
Bead Unseating Block
3.8.2. Bead Unseating Resistance Test for LT/C Tubeless Tyres with Rim Codes of 10
or Greater
3.8.2.1. Requirements
When a tubeless LT/C tyre is tested in accordance with the procedure described
in this section, the applied force required to unseat the tyre bead at the point of
contact shall be not less than:
(a)
(b)
(c)
6,670N (1,500lb) for tyres with a nominal section width of less than
160mm (6in);
8,890N (2,000lb) for tyres with a nominal section width of 160mm (6in) or
more but less than 205mm (8in);
11,120N (2,500lb) for tyres with a nominal section width of 205mm (8in) or
more.

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Table 16
'A' dimensions
Table of A dimension for different rim codes
Rim code mm Inches
20 345 13.50
19 330 13.00
18 318 12.50
17 305 12.00
16 292 11.50
15 279 11.00
14 267 10.50
13 254 10.00
12 241 9.50
11 229 9.00
10 216 8.50
320 216 8.50
340 229 9.00
345 235 9.25
365 248 9.75
370 254 10.00
390 279 11.00
415 292 11.50

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3.8.2.3. Test Procedure
Figure 9
Diagram of Bead Unseating Block (all dimensions in mm)
3.8.2.3.1. Apply a load through the block to the tyre's outer sidewall at the distance
specified in Figure 8 for the applicable wheel size at a rate (50 ± 2.5)mm/min
((2 ± 0.1)in/min), with the load arm substantially parallel to the tyre and rim
assembly at the time of engagement.
3.8.2.3.2. Increase the load until the bead unseats or the applicable value specified in
Paragraph 3.8.2.1. is reached.
3.8.2.3.3. Repeat the test at least four places equally spaced around the tyre
circumference.

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3.9.1.1.3.3. Conduct the test, without interruptions, at not less than 120km/h (110km/h for
snow tyres for use in severe snow conditions and marked with the three peak
mountain snowflake) test speed with loads and test periods not less than those
shown in the table below:
Table 18
Test Programme for Endurance Test of Passenger Car Tyres:
Test period
Duration
Load as a percentage of
the maximum load rating
1 4h 85%
2 6h 90%
3 24h 100%
3.9.1.1.3.4. Throughout the test the inflation pressure shall not be corrected, and the test
loads shall be kept constant at the value corresponding to each test period.
3.9.1.1.3.5. Allow the tyre to cool for between 15 and 25min, then measure its inflation
pressure. Inspect the tyre externally on the test rim for the conditions specified in
Paragraph 3.9.1.1.1., 3.9.1.1.2., and 3.9.1.1.3. above.
3.9.1.2. Low Inflation Pressure Performance Test for Passenger Car Tyres
3.9.1.2.1. Requirements
The following requirements shall be met by tyres when tested in accordance with
the procedure given in Paragraph 3.9.1.2.3. below.
3.9.1.2.1.1. There shall be no visible evidence of tread, sidewall, ply, cord, inner liner, belt or
bead separation, chunking, open splices, cracking or broken cords.
3.9.1.2.1.2. The tyre pressure, when measured at any time between 15min and 25min after
the end of the test, shall not be less than 95% of the initial pressure specified in
Paragraph 3.9.1.2.2. below.
3.9.1.2.2. Preparation of Tyre
This test is conducted following completion of the tyre endurance test using the
same tyre and rim assembly tested in accordance with Paragraph 3.9.1.1 above,
with the tyre deflated to the following pressures show in the table below:

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3.9.2. Non-harmonized Endurance Tests for LT/C Tyres
This section is reserved for a future harmonized endurance test. It currently
contains two non-harmonized endurance tests. When transposing the provisions
of this Regulation to the national/regional legislation, Contracting Parties wishing
to include this kind of test are encouraged to review the sub sections 3.9.2.1.
and 3.9.2.2. based on the provisions of FMVSS 139 and UN Regulation No. 54
respectively.
The endurance test represented in Paragraph 3.9.2.1. is applicable for all LT/C
tyres regardless of speed category symbol and consists of two tests: the
endurance test described in Paragraph 3.9.2.1.1. and the Low inflation pressure
performance test described in Paragraph 3.9.2.1.2. which shall be performed in
sequence. The low inflation pressure performance test is conducted following,
completion of the tyre endurance test using the same tyre and rim assembly.
The endurance test represented in Paragraph 3.9.2.2. is only applicable for LT/C
tyres with Speed Symbol less than "Q".
3.9.2.1. Endurance and Low Inflation Pressure Performance Test for LT/C Tyres
3.9.2.1.1. Endurance Test for LT/C Tyres
3.9.2.1.1.1. Requirements
3.9.2.1.1.1.1. When the tyre is tested in accordance with Paragraph 3.9.2.1.1.3.:
(a)
(b)
There shall be no visual evidence of tread, sidewall, ply, cord, belt or bead
separation, chunking, open splices, cracking or broken cords;
The tyre pressure, when measured at any time between 15min and 25min
after the end of the test, shall not be less than 95% of the initial pressure
specified in Paragraph 3.9.2.1.1.2.1.

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Table 21
Load Programme for Endurance Test
Test period
Duration (hours)
Load as a percentage of
the maximum load rating
1 4 85
2 6 90
3 24 100
3.9.2.1.1.3.4. Throughout the test, the inflation pressure is not corrected, and the test loads are
maintained at the value corresponding to each test period, as shown in the table
in Paragraph 3.9.2.1.1.3.3.
3.9.2.1.1.3.5. Allow the tyre to cool for between 15min and 25min after running the tyre for the
time specified in the table in Paragraph 3.9.2.1.1.3.3., measure its inflation
pressure. Inspect the tyre externally on the test rim for the conditions specified in
Paragraph 3.9.2.1.1.1.1.
3.9.2.1.2. Low Inflation Pressure Performance Test for LT/C Tyres
3.9.2.1.2.1. Requirements
3.9.2.1.2.1.1. When the tyre is tested in accordance with Paragraph 3.9.2.1.2.3.:
(a)
(b)
There shall be no visual evidence of tread, sidewall, ply, cord, inner liner,
belt or bead separation, chunking, open splices, cracking, or broken cords,
and;
The tyre pressure, when measured at any time between 15min and 25min
after the end of the test, shall not be less than 95% of the initial pressure
specified in Paragraph 3.9.2.1.2.2.1.

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3.9.2.2. Endurance Test for LT/C Tyres
3.9.2.2.1. Requirements
3.9.2.2.1.1. An LT/C tyre which, after undergoing the endurance test, does not exhibit any
tread separation, ply separation, cord separation, chunking or broken cords shall
be deemed to have passed the test.
3.9.2.2.1.2. In the case of a tyre which has an alternative Service Description in addition to
the one that is subject to the variation of load with speed given in the table in
Annex 5 to this Regulation, the endurance shall also be carried out on a second
tyre of the same type at the additional load/speed combination.
3.9.2.2.2. Preparing the Tyre
3.9.2.2.2.1. Mount the tyre on a rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre.
3.9.2.2.2.2. Use a new inner tube or combination of inner tube, valve and flap (as required)
when testing tyres with inner tubes.
3.9.2.2.2.3. Inflate the tyre to the Reference Test Inflation Pressure.
3.9.2.2.2.4. Condition the tyre-and-wheel assembly at test-room temperature for not less
than 3h.
3.9.2.2.2.5. Readjust the tyre pressure to that specified in Paragraph 3.9.2.2.2.3. above.
3.9.2.2.3. Test Procedure
3.9.2.2.3.1. Mount the tyre-and-wheel assembly on the test axle and press it against the
outer face of a smooth power-driven test drum 1.7m ± 1% in diameter having a
surface at least as wide as the tyre tread.
3.9.2.2.3.2. Apply to the test axle a series of test loads as defined in Paragraph 3.9.2.2.4.
where the maximum load rating will be the one corresponding to tyre single
application.
3.9.2.2.3.3. The endurance test programme is shown in Paragraph 3.9.2.2.4.
3.9.2.2.3.4. The tyre pressure shall not be corrected throughout the test and the test load
shall be kept constant throughout each of the three test stages.
3.9.2.2.3.5. During the test the temperature in the test-room shall be maintained at between
20°C and 30°C or at a higher temperature if the manufacturer so agrees.

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3.10.1.1. Test Procedure
3.10.1.1.1. Mount a new tyre on the test rim specified by the manufacturer. Mount the tyre
on a test rim with a width comprised between the minimum and maximum width
as per Annex 9. The rim contour shall be one of those specified for the fitment of
the test tyre.
3.10.1.1.2. Condition the tyre at (35 ± 3)°C and 250kPa for 3h.
3.10.1.1.3. Remove the valve core and wait until the tyre deflates completely.
3.10.1.1.4. Mount the tyre-and-wheel assembly to a test axle and press it against the outer
surface of a smooth wheel 1.7m ± 1% or 2.0m ± 1% in diameter.
3.10.1.1.5. Apply to the test axle a load equal to 65% of the maximum load rating.
3.10.1.1.6. At the start of the test, measure the deflected section height (Z1).
3.10.1.1.7. During the test the temperature of the test room shall be maintained at
(35 ± 3)°C.
3.10.1.1.8. Carry the test through, without interruption in conformity with the following
particulars:
Time taken to pass from zero speed to constant test speed: 5min;
Test speed: 80km/h; Duration of test at the test speed: 60min.
3.10.1.1.9. At the end of the test, measure the deflected section height (Z2).
3.10.1.1.10. Calculate the change in per cent of the deflected section height compared to the
deflected section height at the start of the test as ((Z1 – Z2) / Z1) • 100.
3.11. Rolling Sound Emission Test
3.11.1. Requirements
For tyres which are included within the scope of this regulation, except
Professional off-road tyres, tyres fitted with additional devices to improve traction
properties (e.g. studded tyres), tyres with a speed rating less than 80km/h
(speed symbol F) and those having a nominal rim diameter code ≤ 10
(or ≤ 254mm) or ≥ 25 (or ≥ 635mm), the rolling sound emission value shall not
exceed the values given below for Class C1, Class C2 and Class C3 tyres, with
reference to the categories of use and, where relevant, the nominal section
widths, given in the definitions section in Paragraph 2. of this regulation.

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3.11.2. Coast-by Test Method for Measuring Tyre Rolling Sound Emission
The presented method contains specifications on measuring instruments,
measurement conditions and the measurement method, in order to obtain the
sound level of a set of tyres mounted on a test vehicle rolling on a specified road
surface. The maximum sound pressure level is to be recorded, when the test
vehicle is coasting, by remote-field microphones; the final result for a reference
speed is obtained from a linear regression analysis. Such test results cannot be
related to tyre rolling sound measured during acceleration under power or
deceleration under braking.
3.11.3. Measuring Instruments
3.11.3.1. Acoustic Measurements
3.11.3.1.1. Calibration
The sound level meter or the equivalent measuring system, including the
windscreen recommended by the manufacturer shall meet or exceed the
requirements of Type 1 instruments in accordance with IEC 61672-1:2013
standard.
The measurements shall be made using the frequency weighting A, and the time
weighting F.
When using a system that includes a periodic monitoring of the A-weighted
sound level, a reading should be made at a time interval not greater than 30ms.
At the beginning and at the end of every measurement session, the entire
measurement system shall be checked by means of a sound calibrator that fulfils
the requirements for sound calibrators of at least precision Class 1 according to
IEC 60942:2003 standard.
Without any further adjustment the difference between the readings of two
consecutive checks shall be less than or equal to 0.5dB(A). If this value is
exceeded, the results of the measurements obtained after the previous
satisfactory check shall be discarded.
3.11.3.1.2. Compliance with Requirements
The compliance of the sound calibration device with the requirements of
IEC 60942:2003 standard shall be verified once a year and the compliance of
the instrumentation system with the requirements of IEC 61672-1:2013 standard
shall be verified at least every two years, by a laboratory which is authorized to
perform calibrations traceable to the appropriate standards.

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3.11.4. Conditions of Measurement
3.11.4.1. Test Site
The test site shall consist of a central section surrounded by a substantially flat
test area. The measuring section shall be level; the test surface shall be dry and
clean for all measurements. The test surface shall not be artificially cooled during
or prior the testing.
The test track shall be such that the conditions of a free sound field between the
sound source and the microphone are attained to within 1dB(A). These
conditions shall be deemed to be met if there is no large sound reflecting objects
such as fences, rocks, bridges or building within 50m of the centre of the
measuring section. The surface of the test track and the dimensions of the test
site shall be in accordance with ISO 10844:2014.
A central part of at least 10m radius shall be free of powdery snow, tall grass,
loose soil, cinders or the like. There shall be no obstacle, which could affect the
sound field within the vicinity of the microphone and no persons shall stand
between the microphone and the sound source. The operator carrying out the
measurements and any observers attending the measurements shall position
themselves so as not to affect the readings of the measuring instruments.
3.11.4.2. Meteorological Conditions
3.11.4.3. Ambient Noise
Measurements shall not be made under poor atmospheric conditions. It shall be
ensured that the results are not affected by gusts of wind. Testing shall not be
performed if the wind speed at the microphone height exceeds 5m/s.
Measurements shall not be made if the air temperature is below 5°C or above
40°C or the test surface temperature is below 5°C or above 50°C.
3.11.4.3.1. The background sound level (including any wind noise) shall be at least 10dB(A)
less than the measured tyre rolling sound emission. A suitable windscreen may
be fitted to the microphone provided that account is taken of its effect on the
sensitivity and directional characteristics of the microphone.
3.11.4.3.2. Any measurement affected by a sound peak which appears to be unrelated to
the characteristics of the general sound level of tyres, shall be ignored.
3.11.4.4. Test Vehicle Requirements
3.11.4.4.1. General
3.11.4.4.2. Vehicle Load
The test vehicle shall be a motor vehicle and be fitted with four single tyres on
just two axles.
The vehicle shall be loaded such as to comply with the test tyre loads as
specified in Paragraph 3.11.4.5.2. below.

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3.11.4.5. Tyres
3.11.4.5.1. General
3.11.4.5.2. Tyre Loads
Four identical tyres shall be fitted on the test vehicle. In the case of tyres with a
load index in excess of 121 and without any dual fitting indication, two of these
tyres of the same type and range shall be fitted to the rear axle of the test
vehicle; the front axle shall be fitted with tyres of size suitable for the axle load
and planed down to the minimum depth in order to minimize the influence of
tyre/road contact noise while maintaining a sufficient level of safety. Winter tyres
that in certain Contracting Parties may be equipped with studs intended to
enhance friction shall be tested without this equipment. Tyres with special fitting
requirements shall be tested in accordance with these requirements (e.g. rotation
direction). The tyres shall have full tread depth before being run-in.
Tyres are to be tested on test rims with a width comprised between the minimum
and maximum width as per Annex 9. The rim contour shall be one of those
specified for the fitment of the test tyre.
The test load Q for each tyre on the test vehicle shall be 50 to 90% of the
reference load Q , but the average test load Q of all tyres shall be (75 ± 5)% of
the reference load Q .
For all tyres the reference load Q corresponds to the maximum load rating in
single application of the tyre. In the case where the load index is constituted by
two numbers divided by a slash (/), reference shall be made to the first number.
3.11.4.5.3. Tyre Inflation Pressure
Each tyre fitted on the test vehicle shall have a test inflation pressure P not
higher than the P and within the interval:
For Class C2 and Class C3 tyres, P is the Reference Test Inflation Pressure
marked on the tyre.
For Class C1 tyres, P is equal to 250kPa for "standard" or "light load" tyres and
equal to 290kPa for "extra load" tyres; the minimum test inflation pressure shall
be P equal to 150kPa.
3.11.4.5.4. Preparations Prior to Testing
The tyres shall be "run-in" prior to testing to remove compound nodules or other
tyre pattern characteristics resulting from the moulding process. This will
normally require the equivalent of about 100km of normal use on the road.
The tyres fitted to the test vehicle shall rotate in the same direction as when they
were run-in.
Prior to testing tyres shall be warmed up by running under test conditions.

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3.11.6.2. Regression Analysis of Rolling Sound Measurements
The tyre-road rolling sound level L in dB(A) is determined by a regression
analysis according to:
Where:
L is the mean value of the rolling sound levels L , measured in dB(A):
n is the measurement number (n ≥ 16),
is the mean value of logarithms of speeds v :
with
"a"
is the slope of the regression line in dB(A):
3.11.6.3. Temperature Correction
For Class C1 and Class C2 tyres, the final result shall be normalized to a test
surface reference temperature ϑ by applying a temperature correction,
according to the following:
LR(ϑ ) = LR(ϑ) + K(ϑ − ϑ)
Where:
ϑ = the measured test surface temperature
ϑ = 20°C.
For Class C1 tyres, the coefficient K is:
−0.03dB(A)/°C when ϑ > ϑ and
−0.06dB(A)/°C when ϑ < ϑ .

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3.12. Adhesion Performance on Wet Surfaces Test
3.12.1. Requirements
The following requirements do not apply to professional off-road tyres, tyres fitted
with additional devices to improve traction properties (e.g. studded tyres), tyres
with a speed rating less than 80km/h (speed symbol F) and those having a
nominal rim diameter code ≤ 10 (or ≤ 254mm) or ≥ 25 (or ≥ 635mm).
For Class C1 tyres, tested in accordance with either procedure given in
Paragraph 3.12.2., the tyre shall meet the following requirements:
Table 27
Wet Grip Index for Class C1 Tyres
Category of use
Wet grip index
(G)
Normal tyre ≥ 1.1
Snow tyre ≥ 1.1
Special use tyre
"Snow tyre for use in severe snow conditions"
and with a speed symbol ("R" and above,
including "H") indicating a maximum permissible
speed greater than 160km/h
"Snow tyre for use in severe snow conditions"
and with a speed symbol ("Q" or below excluding
"H") indicating a maximum permissible speed
not greater than 160km/h
≥ 1.0
≥ 0.9
Not defined
For Class C2 tyres, tested in accordance with either procedure given in
Paragraph 3.12.3., the tyre shall meet the following requirements:
Table 28
Wet Grip Index for Class C2 Tyres
Category of use
Other
Wet grip index (G)
Traction tyres
Normal tyre ≥ 0.95 ≥ 0.85
Snow tyre ≥ 0.95 ≥ 0.85
Snow tyre for use in severe
snow conditions
≥ 0.85 ≥ 0.85
Special use tyre ≥ 0.85 ≥ 0.85

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3.12.2.2.1.5. The wetted frictional properties of the surface shall be measured with either
method (a) or (b) in Section 3.12.2.2.2..
3.12.2.2.2. Methods to Measure the Wetted Frictional Properties of the Surface
3.12.2.2.2.1. British Pendulum Number (BPN) Method (a)
The British Pendulum Number method shall be as defined in ASTM E 303-93
(Reapproved in 2008).
Pad rubber component formulation and physical properties shall be as specified
in ASTM E 501-08.
The averaged British Pendulum Number (BPN) shall be between 42 and 60BPN
after temperature correction as follows.
BPN shall be corrected by the wetted road surface temperature. Unless
temperature correction recommendations are indicated by the British pendulum
manufacturer, the following formula is used:
BPN = BPN(measured value) + temperature correction
temperature correction = −0.0018 t + 0.34 t − 6.1
where t is the wetted road surface temperature in °C.
Effects of slider pad wear: the pad shall be removed for maximum wear when the
wear on the striking edge of the slider reaches 3.2mm in the plane of the slider or
1.6mm vertical to it in accordance with Section 5.2.2. and Figure 3 of
ASTM E 303-93 (Reapproved 2008).
For the purpose of checking track surface BPN consistency for the measurement
of wet grip on an instrumented passenger car: the BPN values of the test track
should not vary over the entire stopping distance so as to decrease the
dispersion of test results. The wetted frictional properties of the surface shall be
measured five times at each point of the BPN measurement every 10m and the
coefficient of variation of the averaged BPN shall not exceed 10%.

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3.12.2.3.1. Testing Method (a) Using an Instrumented Passenger Car
3.12.2.3.1.1. Principle
3.12.2.3.1.2. Equipment
3.12.2.3.1.2.1. Vehicle
The testing method covers a procedure for measuring the deceleration
performance of Class C1 tyres during braking, using an instrumented passenger
car equipped with an Antilock Braking System (ABS), where "instrumented
passenger car" means a passenger car that is fitted with the measuring
equipment listed in Section 3.12.2.3.1.2.2. for the purpose of this testing method.
Starting with a defined initial speed, the brakes are applied hard enough on four
wheels at the same time to activate the ABS. The average deceleration is
calculated between two pre-defined speeds.
Permitted modifications on the passenger car are as follows:
(a)
(b)
(c)
Those allowing the number of tyre sizes that can be mounted on the
vehicle to be increased;
Those permitting automatic activation of the braking device to be installed;
Any other modification of the braking system is prohibited.
3.12.2.3.1.2.2. Measuring Equipment
The vehicle shall be fitted with a sensor suitable for measuring speed on a wet
surface and distance covered between two speeds.
To measure vehicle speed, a fifth wheel or non-contact speed-measuring system
shall be used.
3.12.2.3.1.3. Conditioning of the Test Track and Wetting Condition
The test track surface shall be watered at least half an hour prior to testing in
order to equalize the surface temperature and water temperature. External
watering should be supplied continuously throughout testing. For the whole
testing area, the water depth shall be (1.0 ± 0.5)mm, measured from the peak of
the pavement.
The test track should then be conditioned by conducting at least 10 test runs with
tyres not involved in the test programme at 90km/h.

---

3.12.2.3.1.5.1.3. The brakes are activated either automatically or manually.
3.12.2.3.1.5.1.3.1. The automatic activation of the brakes is performed by means of a detection
system made of two parts, one indexed to the test track and one on board the
passenger car.
3.12.2.3.1.5.1.3.2. The manual activation of the brakes depends on the type of transmission as
follows. In both cases, a minimum of 600N pedal efforts is required.
For manual transmission, the driver should release the clutch and depress the
brake pedal sharply, holding it down as long as necessary to perform the
measurement.
For automatic transmission, the driver should select neutral gear and then
depress the brake pedal sharply, holding it down as long as necessary to
perform the measurement.
3.12.2.3.1.5.1.4. The average deceleration is calculated between 80km/h and 20km/h.
3.12.2.3.1.5.2. Test Cycle
If any of the specifications listed above (including speed tolerance, longitudinal
and transverse tolerance for the braking starting point, and braking time) are
not met when a test run is made, the measurement is discarded, and a new
test run is made.
A number of test runs are made in order to measure the wet grip index of a set
of candidate tyres (T) according to the following procedure, whereby each test
run shall be made in the same direction and up to three different sets of
candidate tyres may be measured within the same test cycle:
3.12.2.3.1.5.2.1. First, the set of reference tyres are mounted on the instrumented passenger
car.
3.12.2.3.1.5.2.2. After at least three valid measurements have been made in accordance with
Section 3.12.2.3.1.5.1, the set of reference tyres is replaced by a set of
candidate tyres.
3.12.2.3.1.5.2.3. After six valid measurements of the candidate tyres are performed, two more
sets of candidate tyres may be measured.

---

3.12.2.3.1.6.3. Calculation of Adjusted Average Deceleration (Ra)
The average deceleration (AD) of the reference tyre set used for the calculation
of its braking force coefficient is adjusted according to the positioning of each
candidate tyre set in a given test cycle.
This adjusted AD of the reference tyre (Ra) is calculated in m/s in accordance
with the following table where R is the average of the AD values in the first test
of the reference tyre set (R) and R is the average of the AD values in the
second test of the same reference tyre set (R).
Table 30
Adjusted Average Deceleration (Ra) Calculation
Number of sets of
candidate tyres within one
test cycle
Set of candidate tyres
Ra
1
(R – T1 – R )
2
(R – T1 – T2 – R )
3
(R – T1 – T2 – T3 – R )
T1
Ra = 1/2 (R + R )
T1
Ra = 2/3 R + 1/3 R
T2
Ra = 1/3 R + 2/3 R
T1
Ra = 3/4 R + 1/4 R
T2
Ra = 1/2 (R +R )
T3
Ra = 1/4 R + 3/4 R
3.12.2.3.1.6.4. Calculation of the Braking Force Coefficient (BFC)
The braking force coefficient (BFC) is calculated for a braking on the two axles
according to the following table where Ta (a = 1, 2 or 3) is the average of the AD
values for each candidate tyre (T) set that is part of a test cycle
Reference tyre
Candidate tyre
Table 31
Braking Force Coefficient Calculation
Test Tyre
Braking force coefficient
BFC(R) = │Ra/g│
BFC(T) = │Ta/g│
g is the acceleration due to gravity, g = 9.81m/s

---

The wet grip index of the candidate tyre (G(T)) is calculated as follows:
G(T) = G • G
where:
G
is the relative wet grip index of the control tyre (C) compared to the
reference tyre (R) calculated as follows:
G
is the relative wet grip index of the candidate tyre (T) compared to the
control tyre (C) calculated as follows:
3.12.2.3.1.7.3. Storage and Preservation
It is necessary that all the tyres of a control tyre set have been stored in the
same conditions. As soon as the control tyre set has been tested in comparison
with the reference tyre, the specific storage conditions defined in
ASTM E 1136-93 (Reapproved 2003) shall be applied.
3.12.2.3.1.7.4. Replacement of Reference Tyres and Control Tyres
When irregular wear or damage results from tests, or when wear influences the
test results, the use of the tyre shall be discontinued.
3.12.2.3.2. Testing Method (b) Using a Trailer Towed by a Vehicle or a Tyre Test Vehicle
3.12.2.3.2.1. Principle
The measurements are conducted on test tyres mounted on a trailer towed by a
vehicle (hereafter referred to as tow vehicle) or on a tyre test vehicle. The brake
in the test position is applied firmly until sufficient braking torque is generated to
produce the maximum braking force that will occur prior to wheel lockup at a test
speed of 65km/h.

---

3.12.2.3.2.2.2. Measuring Equipment
The test wheel position on the trailer or the tyre test vehicle shall be equipped
with a rotational wheel velocity measuring system and with transducers to
measure the braking force and vertical load at the test wheel.
General requirements for measurement system: The instrumentation system
shall conform to the following overall requirements at ambient temperatures
between 0°C and 45°C:
(a)
(b)
Overall system accuracy, force: ±1.5% of the full scale of the vertical load
or braking force;
Overall system accuracy, speed: ±1.5% of speed or ±1.0km/h, whichever
is greater.
Vehicle speed: To measure vehicle speed, a fifth wheel or non-contact precision
speed-measuring system should be used.
Braking forces: The braking force-measuring transducers shall measure
longitudinal force generated at the tyre-road interface as a result of brake
application within a range from 0% to at least 125% of the applied vertical load.
The transducer design and location shall minimize inertial effects and
vibration-induced mechanical resonance.
Vertical load: The vertical load-measuring transducer shall measure the vertical
load at the test position during brake application. The transducer shall have the
same specifications as described previously.
Signal conditioning and recording system: All signal conditioning and recording
equipment shall provide linear output with necessary gain and data reading
resolution to meet the specified previous requirements. In addition, the following
requirements apply:
(a)
The minimum frequency response shall be flat from 0Hz to 50Hz (100Hz)
within ±1% full scale;
(b) The signal-to-noise ratio shall be at least 20/1;
(c)
(d)
(e)
The gain shall be sufficient to permit full-scale display for full-scale input
signal level;
The input impedance shall be at least 10 times larger than the output
impedance of the signal source;
The equipment shall be insensitive to vibrations, acceleration, and
changes in ambient temperature.
3.12.2.3.2.3. Conditioning of the Test Track
The test track should be conditioned by conducting at least 10 test runs with
tyres not involved in the test programme at (65 ± 2)km/h.

---

3.12.2.3.2.5.2. Tyre Load
The test load on the test tyre is (75 ± 5)% of the maximum load rating.
3.12.2.3.2.5.3. Tyre Inflation Pressure
The test tyre cold inflation pressure shall be 180kPa for standard-load tyres. For
extra load tyres, the cold inflation pressure shall be 220kPa.
The tyre pressure should be checked just prior to testing at ambient temperature
and adjusted if required.
3.12.2.3.2.6. Preparation of the Tow Vehicle and Trailer or the Tyre Test Vehicle
3.12.2.3.2.6.1. Trailer
For one axle trailers, the hitch height and transverse position shall be adjusted
once the test tyre has been loaded to the specified test load in order to avoid any
disturbance of the measuring results. The longitudinal distance from the centre
line of the articulation point of the coupling to the transverse centre line of the
axle of the trailer shall be at least 10 times the "hitch height" or the "coupling
(hitch) height".
3.12.2.3.2.6.2. Instrumentation and Equipment
3.12.2.3.2.7. Procedure
3.12.2.3.2.7.1. Test Run
Install the fifth wheel, when used, in accordance with the manufacturer's
specifications and locate it as near as possible to the mid-track position of the
tow trailer or the tyre test vehicle.
The following procedure applies for each test run:
3.12.2.3.2.7.1.1. The tow vehicle or the tyre test vehicle is driven onto the test track in a straight
line at the specified test speed (65 ± 2)km/h.
3.12.2.3.2.7.1.2. The recording system is launched.
3.12.2.3.2.7.1.3. Water is delivered to the pavement ahead of the test tyre approximately 0.5s
prior to brake application (for internal watering system).
3.12.2.3.2.7.1.4. The trailer brakes are activated within 2m of a measurement point of the wetted
frictional properties of the surface and sand depth in accordance with
Paragraphs 3.12.2.2.1.4. and 3.12.2.2.1.5.. The rate of braking application shall
be such that the time interval between initial application of force and peak
longitudinal force is in the range 0.2s to 0.5s.
3.12.2.3.2.7.1.5. The recording system is stopped.

---

3.12.2.3.2.8.2. Validation of Results
The μ coefficient of variation is calculated as follows:
(Standard Deviation / Average) • 100
For the reference tyre (R): If the coefficient of variation of the peak braking force
coefficient (μpeak) of the reference tyre is higher than 5%, all data should be
discarded, and the test repeated for all test tyres (the candidate tyre(s) and the
reference tyre).
For the candidate tyre(s) (T): The coefficient of variation of the peak braking
force coefficient (μ ) is calculated for each candidate tyre. If one coefficient of
variation is higher than 5%, the data should be discarded, and the test repeated
for this candidate tyre.
3.12.2.3.2.8.3. Calculation of the Adjusted Average Peak Braking Force Coefficient
The average peak braking force coefficient of the reference tyre used for the
calculation of its braking force coefficient is adjusted according to the positioning
of each candidate tyre in a given test cycle.
This adjusted average peak braking force coefficient of the reference tyre (Ra) is
calculated in accordance with the following table where R is the average peak
tyre braking coefficient in the first test of the reference tyre (R) and R is the
average peak tyre braking coefficient in the second test of the same reference
tyre (R).
Table 32
Adjusted Average Peak Braking Force Coefficient of the Reference Tyre (Ra) Calculation
Number of candidate
tyre(s) within one test
cycle
Candidate tyre
Ra
1
(R – T1 – R )
2
(R – T1 – T2 – R )
3
(R – T1 – T2 – T3 – R )
T1
Ra = 1/2 (R + R )
T1
Ra = 2/3 R + 1/3 R
T2
Ra = 1/3 R + 2/3 R
T1
Ra = 3/4 R + 1/4 R
T2
Ra = 1/2 (R +R )
T3
Ra = 1/4 R + 3/4 R

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3.12.3. Class C2 and Class C3 Tyres
3.12.3.1. General Test Conditions
3.12.3.1.1. Track Characteristics
The surface shall be a dense asphalt surface with a uniform gradient of not more
than 2% and shall not deviate more than 6mm when tested with a 3m
straightedge.
The test surface shall have a pavement of uniform age, composition, and wear.
The test surface shall be free of loose material or foreign deposits.
The maximum chipping size shall be from 8mm to 13mm.
The sand depth measured as specified in EN13036-1:2001 and ASTM E 965-96
(reapproved 2006) shall be (0.7 ± 0.3)mm.
The surface friction value for the wetted track shall be established by one or
other of the following methods.
3.12.3.1.1.1. Standard Reference Test Tyre (SRTT) Method
The average peak braking coefficient (μ peak average) of the ASTM E1136 - 93
(reapproved 2003) reference tyre (Test method using a trailer, or a tyre test
vehicle as specified in Clause 2.1) shall be (0.7 ± 0.1) (at 65km/h and 180kPa).
The measured values shall be corrected for the effects of temperature as follows:
pbfc = pbfc (measured) + 0.0035 • (t − 20)
Where "t" is the wetted track surface temperature in °C.
The test shall be conducted using the lanes and length of the track to be used for
the wet grip test.
For the trailer method, testing is run in such a way that braking occurs within
10m distance of where the surface was characterized.

---

3.12.3.1.4. In order to cover the range of the tyre sizes fitting the commercial vehicles, three
Standard Reference Testing Tyre (SRTT) sizes shall be used to measure the
relative wet index:
(a) SRTT 315/70R22.5 LI=154/150, ASTM F2870;
(b) SRTT 245/70R19.5 LI=136/134, ASTM F2871;
(c) SRTT 225/75 R 16 C LI=116/114, ASTM F2872.
The three standard reference testing tyre sizes shall be used to measure the
relative wet index as shown in the following table:
Table 34
Standard Reference Testing Tyre Size Selection
For Class C3 tyres
Narrow family
Wide family
S < 285mm
S ≥ 285mm
SRTT 245/70R19.5 LI=136/134 SRTT 315/70R22.5 LI=154/150
For Class C2 tyres
SRTT 225/75 R 16 C LI=116/114
S = Tyre nominal section width
3.12.3.2. Test Procedure
The comparative wet grip performance shall be established using either:
(a)
A trailer or special purpose tyre evaluation vehicle; or
(b) A standard production vehicle as defined in Special Resolution No. 1
concerning the common definitions of vehicle categories, masses and
dimensions (S.R.1) contained in ECE/TRANS/WP.29/1045 and
subsequent amendments.

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3.12.3.2.1.2. Test Procedure
3.12.3.2.1.2.1. Mount the tyre on a test rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre.
Ensure proper bead seating by the use of a suitable lubricant. Excessive use of
lubricant should be avoided to prevent slipping of the tyre on the wheel rim.
Check the test tyres for the specified inflation pressure at ambient temperature
(cold), just prior to testing. For the purpose of this standard the testing tyre cold
inflation pressure P shall be calculated as follows:
Where:
P
is the Reference Test Inflation pressure.
Q = The static test load of the tyre
Q = The maximum load rating of the tyre
3.12.3.2.1.2.2. For tyre break-in, two braking runs are performed. The tyre shall be conditioned
for a minimum of 2h such that it is stabilized at the ambient temperature of the
test track area. The tyre(s) shall not be exposed to direct sunshine during
conditioning.
3.12.3.2.1.2.3. The load conditions for testing shall be 75 ± 5% of the maximum load rating.
3.12.3.2.1.2.4. Shortly before testing, the track shall be conditioned by carrying out at least
10 braking test runs at 50km/h on the part of the track to be used for the
performance test programme but using a tyre not involved in that programme;
3.12.3.2.1.2.5. Immediately prior to testing, the tyre inflation pressure shall be checked and
reset, if necessary, to the values given in Paragraph 3.12.3.2.1.2.1.
3.12.3.2.1.2.6. The test speed shall be at 50 ± 2km/h and shall be maintained between these
limits throughout the test run.
3.12.3.2.1.2.7. The direction of the test shall be the same for each set of tests and shall be the
same for the test tyre as that used for the SRTT with which its performance is to
be compared.
3.12.3.2.1.2.8. Deliver water to the pavement ahead of the test tyre approximately 0.5s prior to
brake application (for internal watering system). The brakes of the test wheel
assembly shall be applied such that peak braking force is achieved within 0.2s
and 1.0s of brake application.

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3.12.3.2.1.2.13. Validation of Results
For the reference tyre:
If the coefficient of variation of the peak braking coefficient, which is calculated
by "standard deviation/average x 100" of the reference tyre is higher than 5%,
discard all data and repeat the test for this reference tyre.
For the candidate tyres:
The coefficients of variation (standard deviation/average x 100) are calculated for
all the candidate tyres. If one coefficient of variation is greater than 5%, discard
the data for this candidate tyre and repeat the test.
If R1 is the average of the peak braking coefficient in the first test of the
reference tyre, R2 is the average of the peak braking coefficient in the second
test of the reference tyre, the following operations are performed, according to
the following table:
Table 35
"Ra" Calculation
If the number of sets of
candidate tyres between
two successive runs of the
reference tyre is:
and the set of candidate
tyres to be qualified is:
then "Ra" is calculated by
applying the following:
1
(R1 – T1 – R2)
2
(R1 – T1 – T2 – R2)
3
(R1 – T1 – T2 – T3 – R2)
T1
Ra = 1/2 (R1 + R2)
T1
Ra = 2/3 R1 + 1/3 R2
T2
Ra = 1/3 R1 + 2/3 R2
T1
Ra = 3/4 R1 + 1/4 R2
T2
Ra = 1/2 (R1 +R2)
T3
Ra = 1/4 R1 + 3/4 R2
3.12.3.2.1.2.14. The wet grip index (G) shall be calculated as:
Wet grip index (G) = μ (T)/μ (R)
It represents the relative Wet Grip Index for braking performance of the
candidate tyre (T) compared to the reference tyre (R).

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3.12.3.2.2.2.3. Tyre Inflation Pressure
(a)
For a vertical load higher or equal to 75% of the maximum load rating of
the tyre, the test inflation pressure "P " shall be calculated as follows:
P = P • (Q /Q )
P
is the Reference Test Inflation Pressure.
Q = The static test load of the tyre
Q = The maximum load rating of the tyre
(b)
For a vertical load lower than 75% of the maximum load rating of the tyre,
the test inflation pressure P shall be calculated as follows:
P = P • (0.75) = (0.7) • P
P
Is the Reference Test Inflation Pressure.
3.12.3.2.2.2.4. Tyre Load
Check the tyre pressure just prior to testing at ambient temperature.
The static load on each axle shall remain the same throughout the test
procedure. The static load on each tyre shall lie between 60% and 100%
maximum load rating of the candidate tyre's. This value shall not exceed 100%
of the maximum load rating of the reference tyre.
Tyre load on the same axle should not differ by more than 10%.
The use of fitting as per Configuration 2 and Configuration 3 shall fulfil the
following additional requirements:
Configuration 2: Front axle load > Rear axle load
The rear axle may be indifferently fitted with two or four tyres
Configuration 3: Rear axle load > Front axle load • 1.8

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3.12.3.2.2.2.6.3. Test Running Order
Examples:
The run order for a test of three sets of candidate tyres (T1 to T3) plus a
reference tyre R would be:
R – T1 – T2 – T3 – R
The run order for a test of five sets of tyres (T1 to T5) plus a reference tyre R
would be:
R – T1 – T2 – T3 – R – T4 – T5 – R
3.12.3.2.2.2.6.4. The direction of the test shall be the same for each set of tests and shall be the
same for the candidate test tyre as that used for the SRTT with which its
performance is to be compared.
3.12.3.2.2.2.6.5. For each test and for new tyres, the first two braking measurements are
discarded.
3.12.3.2.2.2.6.6. After at least three valid measurements have been made in the same direction,
the reference tyres are replaced by a set of the candidate tyres (one of the three
configurations presented in Paragraph 3.12.3.2.2.2.2.) and at least six valid
measurements shall be performed.
3.12.3.2.2.2.6.7. A maximum of three sets of candidate tyres can be tested before the reference
tyre is re-tested.
3.12.3.2.2.2.7. Processing of Measurement Results
3.12.3.2.2.2.7.1. Calculation of the Average Deceleration (AD)
Each time the measurement is repeated, the average deceleration AD (m∙s ) is
calculated by:
Where d (m) is the distance covered between the initial speed S (m∙s ) and the
final speed S (m∙s ).

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3.12.3.2.2.2.7.4. Calculation of Braking Force Coefficient, BFC
BFC(R) and BFC(T) are calculated according to the following table:
Reference tyre
Candidate tyre
Table 37
Braking Force Coefficient Calculation
Tyre type
Braking force coefficient is
BFC(R) = Ra/g
BFC(T) = Ta/g
g is the acceleration due to gravity (rounded to 9.81 m⋅s ).
Ta (a = 1, 2, etc.) is the average of the AD values for a test of a candidate tyre.
3.12.3.2.2.2.7.5. Calculation of the Relative Wet Grip Performance Index of the Tyre
The Wet grip index represents the relative performance of the candidate tyre
compared to the reference tyre. The way to obtain it depends on the test
configuration as defined in Paragraph 3.12.3.2.2.2.2. The wet grip index of the
tyre is calculated as reported into the following table:
Configuration 1:
candidate tyres
on both axles
Configuration 2:
candidate tyres
on
front
axle
and
reference
tyres
on
rear
axle
Configuration 3:
reference tyres
on
front
axle
and
candidate
tyres
on
rear
axle
Table 38
Wet Grip Index Calculation

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3.12.3.2.2.2.8. Wet Grip Performance Comparison Between a Candidate Tyre and a Reference
Tyre Using a Control Tyre
When the candidate tyre size is significantly different from the reference tyre, a
direct comparison on the same vehicle may be not possible. This approach uses
an intermediate tyre, hereinafter called the control tyre.
3.12.3.2.2.2.8.1. The principle lies upon the use of a control tyre and two different vehicles for
assessing a candidate tyre in comparison with a reference tyre.
One vehicle can fit the reference tyre and the control tyre, the other the control
tyre and the candidate tyre. All conditions are in conformity with
Paragraphs 3.12.3.2.2.2.1. to 3.12.3.2.2.2.5. above.
3.12.3.2.2.2.8.2. The first assessment is a comparison between the control tyre and the reference
tyre. The result (Wet Grip Index 1) is the relative efficiency of the control tyre
compared to the reference tyre.
3.12.3.2.2.2.8.3. The second assessment is a comparison between the candidate tyre and the
control tyre. The result (Wet Grip Index 2) is the relative efficiency of the
candidate tyre compared to the control tyre.
The second assessment is done on the same track as the first one and within
one week maximum. The wetted surface temperature shall be in the range of
±5°C of the temperature of the first assessment. The control tyre set (four or six
tyres) is physically the same set as the set used for the first assessment.
3.12.3.2.2.2.8.4. The wet grip index of the candidate tyre compared to the reference tyre is
deduced by multiplying the relative efficiencies calculated above:
(Wet Grip Index 1 • Wet Grip Index 2)
Note: When the test expert decides to use an SRTT tyre as a control tyre (i.e. in
the test procedure two SRTTs are compared directly instead of an SRTT
with a control tyre) the result of the comparison between the SRTTs is
called the "local shift factor".
It is permitted to use a previous SRTTs comparison.
The comparison results shall be checked periodically.
3.12.3.2.2.2.8.5. Selection of a Set of Tyres as a Control Tyre Set
A "control tyre" set is a group of identical tyres made in the same factory during a
one-week period.
3.12.3.2.2.2.8.6. Reference and Control Tyres
Before the first assessment (control tyre/reference tyre), normal storage
conditions can be used. It is necessary that all the tyres of a control tyre set have
been stored in the same conditions.

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3.13.2. Test Methods
The alternative measurement methods listed below are given in this Regulation.
The choice of an individual method is left to the tester. For each method, the test
measurements shall be converted to a force acting at the tyre/drum interface.
The measured parameters are:
(a)
In the force method: the reaction force measured or converted at the tyre
spindle ;
(b) In the torque method: the torque input measured at the test drum;
(c)
(d)
In the deceleration method: the measurement of deceleration of the test
drum and tyre assembly .
In the power method: the measurement of the power input to the test
drum .
3.13.3. Test Equipment
3.13.3.1. Drum Specifications
3.13.3.1.1. Diameter
3.13.3.1.2. Surface
3.13.3.1.3. Width
The test dynamometer shall have a cylindrical flywheel (drum) with a diameter of
at least 1.7m.
The F and C values shall be expressed relative to a drum diameter of 2.0m. If
drum diameter different than 2.0m is used, a correlation adjustment shall be
made following the method in Paragraph 3.13.7.3.
The surface of the drum shall be smooth steel. Alternatively, in order to improve
skim test reading accuracy, a textured surface may also be used, which should
be kept clean.
The F and C values shall be expressed relative to the "smooth" drum surface. If
a textured drum surface is used, see Annex 8, Paragraph 7.
The width of the drum test surface shall exceed the width of the test tyre contact
patch.

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3.13.4.2. Test Speeds
The value shall be obtained at the appropriate drum speed specified in Table 40.
Table 40
Test Speeds (in km/h)
Tyre Class C1 C2 and C3 C3
Load Index All LI ≤ 121 LI > 121
Speed Symbol
3.13.4.3. Test Load
All
All
J 100km/h and
lower or tyres
not marked
with speed
symbol
K 110km/h and
higher
Speed Symbol 80 80 60 80
The standard test load shall be computed from the values shown in Table 41 and
shall be kept within the tolerance specified in Annex 8.
3.13.4.4. Test Inflation Pressure
The inflation pressure shall be in accordance with that shown in Table 41 and
shall be capped with the accuracy specified in Paragraph 4. of Annex 8.
Table 41
Test Loads and Inflation Pressures
Tyre Class
Test Load (% of
the maximum load
rating)
Test Inflation
Pressure kPa
C1
Standard Load
Extra Load
80
80
210
250
C2, C3
85
(% of single load)
Reference Test
Inflation Pressure
Note: The inflation pressure shall be capped with the accuracy specified in
Paragraph 4 of Annex 8.

---

3.13.5.5.
Measurement and Recording
The following shall be measured and recorded (see Figure 10):
(a)
Test speed U ;
(b)
Load on the tyre normal to the drum surface L ;
(c)
The initial test inflation pressure as defined in Paragraph 3.13.4.3.;
(d)
(e)
The coefficient of rolling resistance measured C , and its corrected value
C , at 25°C and for a drum diameter of 2.0m;
The distance from the tyre axis to the drum outer surface under steady
state r ;
(f) Ambient temperature t ;
(g) Test drum radius R;
(h)
(i)
(j)
Test method chosen;
Test rim (size and material);
Tyre size, manufacturer, type, identity number (if one exists), speed
symbol, load index, TIN (Tyre Identification Number).
Figure 10
All the mechanical quantities (forces, torques) will be orientated in accordance
with the axis systems specified in ISO 8855:1991.
The directional tyres shall be run in their specified rotation sense.

---

3.13.5.7. Allowance for Machines Exceeding σ Criterion
The steps described in Paragraphs 3.13.5.3. to 3.13.5.5. shall be carried out
once only, if the measurement standard deviation determined in accordance with
Paragraph 3.13.7.5. is:
(a)
(b)
Not greater than 0.075N/kN for Class C1 and Class C2 tyres;
Not greater than 0.06N/kN for Class C3 tyres.
If the measurement standard deviation exceeds this criterion, the measurement
process will be repeated n times as described in Paragraph 3.13.7.5. The rolling
resistance value reported shall be the average of the n measurements.
3.13.6. Data Interpretation
3.13.6.1. Determination of Parasitic Losses
3.13.6.1.1. General
The laboratory shall perform the measurements described in
Paragraph 3.13.5.6.1. for the force, torque and power methods or those
described in Paragraph 3.13.5.6.2. for the deceleration method, in order to
determine precisely in the test conditions (load, speed, temperature) the tyre
spindle friction, the tyre and wheel aerodynamic losses, the drum (and as
appropriate, engine and/or clutch) bearing friction, and the drum aerodynamic
losses.
The parasitic losses related to the tyre/drum interface F expressed in newtons
shall be calculated from the force F torque, power or the deceleration, as shown
in Paragraphs 3.13.6.1.2. to 3.13.6.1.5. below.
3.13.6.1.2. Force Method at Tyre Spindle
Calculate: F = F • (1 + r /R)
Where:
F is the tyre spindle force in newtons (see Paragraph 3.13.5.6.1.),
r
R
is the distance from the tyre axis to the drum outer surface under steady
state conditions, in meters,
is the test drum radius, in meters.

---

or
Where:
I
R
is the test drum inertia in rotation, in kilograms meter squared,
is the test drum surface radius, in meters,
j is the deceleration of the test drum, without tyre, in radians per second
squared,
I
R
is the spindle, tyre and wheel inertia in rotation, in kilograms meter
squared,
is the tyre rolling radius, in meters,
j is the deceleration of unloaded tyre, in radians per second squared.
3.13.6.2. Rolling Resistance Calculation
3.13.6.2.1. General
The rolling resistance F , expressed in newtons, is calculated using the values
obtained by testing the tyre to the conditions specified in Paragraphs 3.13.4. and
by subtracting the appropriate parasitic losses F , obtained according to
Paragraph 3.13.6.1.
3.13.6.2.2. Force Method at Tyre Spindle
The rolling resistance F , in newtons, is calculated using the equation
F = F • [1 + (r /R)] – F
Where:
F
is the tyre spindle force in newtons,
F represents the parasitic losses as calculated in Paragraph 3.13.6.1.2.,
r
R
is the distance from the tyre axis to the drum outer surface under
steady-state conditions, in meters,
is the test drum radius, in meters.

---

3.13.6.2.5. Deceleration Method
The rolling resistance F , in newtons, is calculated using the equation:
Where:
I
R
is the test drum inertia in rotation, in kilograms meter squared,
is the test drum surface radius, in meters,
F represents the parasitic losses as calculated in Paragraph 3.13.6.1.5.,
Δt
Δω
I
R
F
is the time increment chosen for measurement, in seconds,
is the test drum angular speed increment, without tyre, in radians per
second,
is the spindle, tyre and wheel inertia in rotation, in kilograms meter
squared,
is the tyre rolling radius, in meters,
is the rolling resistance, in newtons.
Or
Where:
I
R
is the test drum inertia in rotation, in kilograms meter squared,
is the test drum surface radius, in meters,
F represents the parasitic losses as calculated in Paragraph 3.13.6.1.5.,
j
I
R
F
is the deceleration of the test drum, in radians per second squared,
is the spindle, tyre and wheel inertia in rotation, in kilograms meter
squared,
is the tyre rolling radius, in meters,
is the rolling resistance, in newtons.

---

3.13.7.3. Drum Diameter Correction
Test results obtained from different drum diameters shall be compared by using
the following theoretical formula:
with:
Where:
R
R
r
is the radius of drum 1, in meters,
is the radius of drum 2, in meters,
is one-half of the nominal design tyre diameter, in meters,
F is the rolling resistance value measured on drum 1, in newtons,
F is the rolling resistance value measured on drum 2, in newtons.
3.13.7.4. Measurement Result
Where n measurements are greater than 1, if required by Paragraph 3.13.5.6.,
the measurement result shall be the average of the C values obtained for the n
measurements, after the corrections described in Paragraphs 3.13.7.2. and
3.13.7.3. have been made.

---

3.14. Snow Performance Test Relative to Snow Tyre for Use in Severe Snow
Conditions
In order to be classified as a "snow tyre for use in severe snow conditions" the
tyre shall meet the performance requirements of Paragraph 3.14.1. The tyre shall
meet these requirements based on a test method by which:
(a)
(b)
(c)
the mean fully developed deceleration ("mfdd") in a braking test;
or alternatively an average traction force in a spin traction test;
or alternatively the average acceleration in an acceleration test;
Class of
tyre
of the candidate tyre is compared to that of a standard reference tyre.
The relative performance shall be indicated by a snow index.
3.14.1. Tyre Snow Performance Requirements
The following requirements does not apply to professional off-road tyres, tyres
fitted with additional devices to improve traction properties (e.g. studded tyres),
tyres with a speed rating less than 80km/h (speed symbol F) and those having a
nominal rim diameter code ≤ 10 (or ≤ 254mm) or ≥ 25 (or ≥ 635mm).
3.14.1.1. Class C1, Class C2 and Class C3 Tyres
The minimum snow index value, as calculated in the procedure described in this
paragraph for the different class of tyres, shall be as follows:
Snow grip index
(brake on snow method)
Table 43
Minimum Snow Grip Index
Snow grip index
(spin traction
method)
Snow grip index
(acceleration method)
Ref. = C1 – SRTT 14 Ref. = C2 – SRTT 16C Ref. = C1 – SRTT 14 Ref. = C3N – SRTT 19.5
Ref. = C3W – SRTT 22.5
C1 1.07 No 1.10 No
C2 No 1.02 1.10 No
C3 No No No 1.25

---

3.14.3.1.3. Tyres
The tyres should be "broken-in" prior to testing to remove spew, compound
nodules or flashes resulting from the moulding process. The tyre surface in
contact with snow shall be cleaned before performing a test.
Tyres shall be conditioned at the outdoor ambient temperature at least 2h before
their mounting for tests. Tyre pressures shall then be adjusted to the values
specified for the test.
In case a vehicle cannot accommodate both the reference and candidate tyres, a
third tyre ("control" tyre) may be used as an intermediate. First test control vs.
reference on another vehicle, then test candidate vs. control on the vehicle.
3.14.3.1.4. Load and Pressure:
3.14.3.1.4.1. For Class C1 tyres, the vehicle load shall be such that the resulting loads on the
tyres are between 60% and 90% of the maximum load rating.
The cold inflation pressure shall be 240kPa.
3.14.3.1.4.2. For Class C2 tyres, the vehicle load shall be such that the resulting loads on the
tyres are between 60% and 100% of the maximum load rating in single
application.
The static tyre load on the same axle should not differ by more than 10%.
The inflation pressure is calculated to run at constant deflection:
For a vertical load higher or equal to 75% of the maximum load rating of the tyre,
a constant deflection is applied, hence the test inflation pressure P shall be
calculated as follows:
Q
P
Q
is the maximum load rating.
is the Reference Test Inflation Pressure
is the static test load of the tyre

---

3.14.3.2.2. Order of Testing:
If only one candidate tyre is to be evaluated, the order of testing shall be:
R1 – T – R2
Where:
R1
R2
T
is the initial test of the SRTT,
is the repeat test of the SRTT and
is the test of the candidate tyre to be evaluated.
A maximum of two candidate tyres may be tested before repeating the SRTT
test, for example:
R1 – T1 – T2 – R2.
3.14.3.2.3. The comparative tests of SRTT and candidate tyres shall be repeated on two
different days.
3.14.3.3. Test Procedure
3.14.3.3.1. Drive the vehicle at a speed not lower than 28km/h.
3.14.3.3.2. When the measuring zone has been reached, the vehicle gear is set into neutral,
the brake pedal is depressed sharply by a constant force sufficient to cause
operation of the ABS on all wheels of the vehicle and to result in stable
deceleration of the vehicle and held down until the speed is lower than 8km/h.
3.14.3.3.3. The mean fully developed deceleration between 25km/h and 10km/h shall be
computed from time, distance, speed, or acceleration measurements.
3.14.3.4. Data Evaluation and Presentation of Results
3.14.3.4.1. Parameters to be Reported
3.14.3.4.1.1. For each tyre and each braking test, the mean and standard deviation of the
mfdd shall be computed and reported.
The coefficient of variation CV of a tyre braking test shall be computed as:

---

3.14.3.4.3. In the case where the candidate tyres cannot be fitted to the same vehicle as the
SRTT, for example, due to tyre size, inability to achieve required loading and so
on, comparison shall be made using intermediate tyres, hereinafter referred to as
"control tyres", and two different vehicles. One vehicle shall be capable of being
fitted with the SRTT and the control tyre and the other vehicle shall be capable of
being fitted with the control tyre and the candidate tyre.
3.14.3.4.3.1. The snow grip index of the control tyre relative to the SRTT (SG1) and of the
candidate tyre relative to the control tyre (SG2) shall be established using the
procedure in Paragraphs 3.14.3.1. to 3.14.3.4.2.
The snow grip index of the candidate tyre relative to the SRTT shall be the
product of the two resulting snow grip indices that is SG1 • SG2.
3.14.3.4.3.2. The ambient conditions shall be comparable. All tests shall be completed within
the same day.
3.14.3.4.3.3. The same set of control tyres shall be used for comparison with the SRTT and
with the candidate tyre and shall be fitted in the same wheel positions.
3.14.3.4.3.4. Control tyres that have been used for testing shall subsequently be stored under
the same conditions as required for the SRTT.
3.14.3.4.3.5. The SRTT and control tyres shall be discarded if there is irregular wear or
damage or when the performance appears to have been deteriorated.
3.14.4. Acceleration Method for Class C3 Tyres
3.14.4.1. According to the definition of Class C3 tyres reported into Paragraph 2.17., the
additional classification for the purpose of this test method only applies:
(a)
(b)
Class C3 Narrow (C3N), when the Class C3 tyre Nominal Section Width is
lower than 285mm;
Class C3 Wide (C3W), when the Class C3 tyre Nominal Section Width is
greater or equal to 285mm.
3.14.4.2. Methods for Measuring Snow Grip Index
Snow performance is based on a test method by which the average acceleration
in an acceleration test, of a candidate tyre is compared to that of a standard
reference tyre.
The relative performance shall be indicated by a Snow Grip Index (SG).
When tested in accordance with the acceleration test in Paragraph 3.14.4.7., the
average acceleration of a candidate snow tyre shall be at least 1.25 compared to
one of the two equivalent SRTTs – ASTM F 2870 and ASTM F 2871.

---

3.14.4.4. General Conditions
3.14.4.4.1. Test Course
The test shall be done on a flat test surface of sufficient length and width, with a
maximum 2% gradient, covered with packed snow.
3.14.4.4.1.1. The snow surface shall be composed of a hard packed snow base at least 3cm
thick and a surface layer of medium packed and prepared snow about 2cm thick.
3.14.4.4.1.2. The snow compaction index measured with a CTI penetrometer shall be
between 80 and 90. Refer to the appendix of ASTM F1805 for additional details
on measuring method.
3.14.4.4.1.3. The air temperature, measured about 1m above the ground, shall be between
−2°C and −15°C; the snow temperature, measured at a depth of about 1cm,
shall be between −4°C and −15°C.
Air temperature shall not vary more than 10°C during the test.
3.14.4.5. Tyres Preparation and Break-in
3.14.4.5.1. Mount the tyre on a test rim with a width comprised between the minimum and
maximum width as per Annex 9. The rim contour shall be one of those specified
for the fitment of the test tyre.
All tyres of the same size have to be tested on the same test rim width and
contour.
Ensure proper bead seating by the use of a suitable lubricant. Excessive use of
lubricant should be avoided to prevent slipping of the tyre on the wheel rim.
3.14.4.5.2. The tyres should be "broken-in" prior to testing to remove spew, compound
nodules or flashes resulting from moulding process.
3.14.4.5.3. Tyres shall be conditioned at the outdoor ambient temperature at least 2h before
their mounting for tests.
They should be placed such that they all have the same ambient temperature
prior to testing and be shielded from the sun to avoid excessive heating by solar
radiation.
The tyre surface in contact with snow shall be cleaned before performing a test.
Tyre pressures shall then be adjusted to the values specified for the test.

---

3.14.4.7.2.1.1. In the particular case where a standard commercial vehicle equipped with a
traction control system is not available, a vehicle without Traction
Control/ASR/TCS is permitted provided the vehicle is fitted with a system to
display the percentage slip as stated in Paragraph 3.14.4.3.4. and a mandatory
differential lock on the driven axle used in accordance with operating procedure
described in Paragraph 3.14.4.7.5.2.1. below. If a differential lock is available it
shall be used; if the differential lock, however, is not available, the average slip
ratio should be measured on the left and right driven wheel.
3.14.4.7.2.2. The permitted modifications are:
(a)
(b)
Those allowing to increase the number of tyre sizes capable to be
mounted on the vehicle;
Those permitting to install an automatic activation of the acceleration and
the measurements.
3.14.4.7.3. Vehicle Fitting
Any other modification of the acceleration system is prohibited.
The rear driven axle may be indifferently fitted with two or four test tyres if
respecting the loading by tyre.
The front steer non-driven axle is equipped with two tyres having a size suitable
for the axle load. These two front tyres could be maintained along the test.
3.14.4.7.4. Load and Inflation Pressure
3.14.4.7.4.1. The static load on each rear driven test tyres must be between 20% and 55% of
the tested maximum load rating of the tested tyre written on the sidewall.
The vehicle front steer total static axle load should be between 60% and 160% of
the driven rear total axle load.
The static tyre load on the same driven axle should not differ by more than 10%.
3.14.4.7.4.2. The driven tyres inflation pressure shall be 70% of the one written on the
sidewall.
The steer tyres are inflated at the Reference Test Inflation Pressure

---

3.14.4.8.2. Validation of Results
For the candidate tyres:
The coefficients of variation of the Average Acceleration is calculated for all the
candidate tyres. If one coefficient of variation is greater than 6%, discard the data
for this candidate tyre and repeat the test.
For the reference tyre:
If the coefficient of variation of the average Acceleration "AA" for each group of
minimum six runs of the reference tyre is higher than 6%, discard all data and
repeat the test for all tyres (the candidate tyres and the reference tyre).
In addition, and in order to take in account possible test evolution, the coefficient
of validation is calculated on the basis of the average values of any two
consecutive groups of minimum six runs of the reference tyre. If the coefficient of
validation is greater than 6%, discard the data for all the candidate tyres and
repeat the test.

---

3.14.4.8.5. Calculation of the Relative Snow Grip Index of the Tyre
The Snow grip index represents the relative performance of the candidate tyre
compared to the reference tyre:
3.14.4.8.6. Calculation of the Slip Ratio
The slip ratio can be calculated as the average of Slip ratio as mentioned in
Paragraph 3.14.4.3.4. or by comparing the average distance referred to in
Paragraph 3.14.4.7.5.3. of the minimum six runs to the distance of a run done
without slip (very low acceleration)
No slip distance means the wheel distance calculated on a run done with a
constant speed or a continuous low acceleration.
3.14.4.9. Snow Grip Performance Comparison Between a Candidate Tyre and a
Reference Tyre Using a Control Tyre
3.14.4.9.1. Scope
When the candidate tyre size is significantly different from the reference tyre a
direct comparison on the same vehicle may be not possible. This is an approach
using an intermediate tyre, hereinafter called the control tyre.
3.14.4.9.2. Principle of the Approach
The principle lies upon the use of a control tyre and two different vehicles for the
assessment of a candidate tyre in comparison with a reference tyre.
One vehicle can fit the reference tyre and the control tyre, the other the control
tyre and the candidate tyre. All conditions are in conformity with
Paragraph 3.14.4.7.
The first assessment is a comparison between the control tyre and the reference
tyre. The result (Snow Grip Index 1) is the relative efficiency of the control tyre
compared to the reference tyre.
The second assessment is a comparison between the candidate tyre and the
control tyre. The result (Snow Grip Index 2) is the relative efficiency of the
candidate tyre compared to the control tyre.
The second assessment is done on the same track as the first one. The air
temperature must be in the range of ± 5°C of the temperature of the first
assessment. The control tyre set is the same set as the set used for the first
assessment.

---

ANNEX 1
SPEED SYMBOL TABLE
Table A1/1
Speed symbol Corresponding speed km/h
F 80
G 90
J 100
K 110
L 120
M 130
N 140
P 150
Q 160
R 170
S 180
T 190
U 200
H 210
V 240
W 270
Y 300

---

ANNEX 3
NOMINAL RIM DIAMETER CODE TABLE
Table A3/1
Nominal rim diameter code ("d" symbol)
Value of the "d" symbol (expressed in mm)
9
229
10
254
11
279
12
305
13
330
14
356
14.5
368
15
381
16
406
16.5
419
17
432
17.5
445
18
457
19
483
19.5
495
20
508
20.5
521
21
533
22
559
22.5
572
23
584
24
610
24.5
622
25
635
26
660
27
686
28
711
29
737
30
762

---

LT/C tyre with a "LT-metric" size designation:
LT225/75R16
or 225/75R16LT
or 225/75R16 118/116N LT
Where
225 is the Nominal Section Width (mm)
75 is the Nominal Aspect Ratio
R
is the Structure or Construction Code
16 is the Nominal Rim Diameter Code
LT
is indicating a Light Truck tyre
118/116 N is the Service Description
LT/C tyre with a "C type" size designation:
225/75R16C
Where
225 is the Nominal Section Width (mm)
75 is the Nominal Aspect Ratio
R
is the Structure or Construction Code
16 is the Nominal Rim Diameter Code
C
is indicating a Commercial tyre
2. HIGH FLOTATION TYRES:
31x10.50R15LT
Where
31 is the Nominal Overall Diameter Code
10.50 is the Nominal Section Width Code, and must end in .50.
R
is the Structure or Construction Code
15 is the Nominal Rim Diameter Code
LT
indicates a Light Truck Tyre
To convert dimensions expressed in code to mm, multiply the code by 25.4 and round to the
nearest mm.

---

ANNEX 5
VARIATION OF LOAD CAPACITY WITH SPEED
Variation of Load Capacity with Speed for Passenger Car Tyres
For speeds not exceeding 210km/h, the load capacity shall not exceed the value associated with the load
index of the tyre.
For speeds above 210km/h, the following table applies:
Speed
(km/h)
Table A5/1
Variation of Load Capacity (%)
Tyre speed symbol
V W Y
210 0 0 0
220 − 3 0 0
230 – 6 0 0
240 – 9 0 0
250 – 5 0
260 – 10 0
270 – 15 0
280 – 5
290 – 10
300 – 15

---

Table A5/2 (continued)
Variation of load capacity (percent)
Speed (km/h)
All load indices
Load indices ≥122
Load indices ≤121
Tyre speed symbol
Tyre speed symbol
Tyre speed symbol
F
G
J
K
L
M
L
M
N
P
115
-7
-3

---

Table A6/2
Tyres for Light Commercial Vehicles
Tyre size
designation
Measuring rim
width code
Minimum rim
width code
Maximum rim
width code
Nominal rim
diameter
d (mm)
Outer
diameter
D (mm)
Section width
S (mm)
145 R 10 C
145 R 12 C
145 R 13 C
145 R 14 C
145 R 15 C
155 R 12 C
155 R 13 C
155 R 14 C
165 R 13 C
165 R 14 C
165 R 15 C
175 R 13 C
175 R 14 C
175 R 16 C
185 R 13 C
185 R 14 C
185 R 15 C
185 R 16 C
195 R 14 C
195 R 15 C
195 R 16 C
205 R 14 C
205 R 15 C
205 R 16 C
215 R 14 C
215 R 15 C
215 R 16 C
245 R 16 C
17 R 15 C
17 R 380 C
17 R 400 C
19 R 400 C
5.60 R 12 C
6.40 R 13 C
6.70 R 13 C
6.70 R 14 C
6.70 R 15 C
4.00
4.00
4.00
4.00
4.00
4.50
4.50
4.50
4.50
4.50
4.50
5.00
5.00
5.00
5.50
5.50
5.50
5.50
5.50
5.50
5.50
6.00
6.00
6.00
6.00
6.00
6.00
7.00
5.00
5.00
150mm
150mm
4.00
4.50
5.00
5.00
5.00
3.50
3.50
3.50
3.50
3.50
4.00
4.00
4.00
4.00
4.00
4.00
4.50
4.50
4.50
5.00
5.00
5.00
5.00
5.00
5.00
5.00
5.50
5.50
5.50
5.50
5.50
5.50
6.50
4.50
4.50
130mm
130mm
3.50
4.00
4.50
4.50
4.50
4.50
4.50
4.50
4.50
4.50
5.00
5.00
5.00
5.00
5.00
5.00
5.50
5.50
5.50
6.00
6.00
6.00
6.00
6.00
6.00
6.00
6.50
6.50
6.50
6.50
6.50
6.50
7.50
5.50
5.50
150mm
150mm
4.50
5.00
5.50
5.50
5.50
254
305
330
356
381
305
330
356
330
356
381
330
356
406
330
356
381
406
356
381
406
356
381
406
356
381
406
406
381
381
400
400
305
330
330
356
381
492
542
566
590
616
550
578
604
596
622
646
608
634
684
624
650
674
700
666
690
716
686
710
736
700
724
750
798
678
678
698
728
570
648
660
688
712
147
147
147
147
147
157
157
157
167
167
167
178
178
178
188
188
188
188
198
198
198
208
208
208
218
218
218
248
178
178
186
200
150
172
180
180
180

---

Table A6/4
Tyres with LT Designation
Outer diameters are listed for the various categories of use: Normal, Snow and Special.
Tyre size
designation
Measuring
rim width
code
Minimum
rim width
code
Maximum
rim width
code
Nominal rim
diameter
d(mm)
Outer diameter
D (mm)
Section
width
S (mm)
Normal
Snow
6.00R16LT
6.50R16LT
6.70R16LT
7.00R13LT
7.00R14LT
7.00R15LT
7.00R16LT
7.10R15LT
7.50R15LT
7.50R16LT
8.25R16LT
9.00R16LT
G78R15LT
H78R15LT
L78R15LT
L78R16LT
7R14.5LT
8R14.5LT
9R14.5LT
7R17.5LT
8R17.5LT
9R15LT
10R15LT
11R15LT
8.00R16.5LT
8.75R16.5LT
9.50R16.5LT
10R16.5LT
12R16.5LT
4.50
4.50
5.00
5.00
5.00
5.50
5.50
5.00
6.00
6.00
6.50
6.50
6.00
6.00
6.50
6.50
6.00
6.00
7.00
5.25
5.25
8.00
8.00
8.00
6.00
6.75
6.75
8.25
9.75
4.50
4.50
4.50
4.50
4.50
5.00
5.00
5.00
5.50
5.50
6.50
6.50
5.50
5.50
6.00
6.00
6.00
6.00
7.00
5.25
5.25
7.00
7.00
8.00
6.00
6.00
6.75
8.25
8.25
4.50
6.00
6.00
5.50
6.00
6.50
6.50
5.50
7.00
7.00
7.00
6.50
7.00
7.00
7.00
7.00
6.00
6.00
7.00
5.25
5.25
8.00
8.50
8.50
6.75
6.75
8.25
8.25
9.75
406
406
406
330
356
381
406
381
381
406
406
406
381
381
381
406
368
368
368
445
445
381
381
381
419
419
419
419
419
732
755
722
647
670
752
778
738
782
808
859
890
711
727
749
775
677
707
711
758
788
744
773
777
720
748
776
762
818
743
767
733
658
681
763
788
749
794
819
869
903
722
739
760
786
–
–
–
769
799
755
783
788
730
759
787
773
831
173
182
191
187
187
202
202
199
220
220
241
257
212
222
236
236
185
203
241
189
199
254
264
279
203
222
241
264
307

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Table A6/5 (continued)
Tyre size
designation
Measuring
rim width
code
Minimum
rim width
code
Maximum
rim width
code
Nominal rim
diameter
d(mm)
Outer diameter
D (mm)
Section
width
S (mm)
Highway
Tread
Traction
Tread
35x12.50R17LT
35x12.50R18LT
35x12.50R20LT
35x12.50R22LT
35x13.50R15LT
35x13.50R18LT
35x13.50R20LT
35x14.50R15LT
36x13.50R18LT
36x14.50R15LT
36x14.50R17LT
36x14.50R18LT
36x15.50R15LT
36x15.50R20LT
37x11.50R20LT
37x12.50R15LT
37x12.50R17LT
37x12.50R18LT
37x12.50R20LT
37x12.50R22LT
37x13.50R15LT
37x13.50R17LT
37x13.50R18LT
37x13.50R20LT
37x13.50R22LT
37x13.50R24LT
37x13.50R26LT
37x14.50R15LT
38x13.50R17LT
38x13.50R20LT
38x13.50R22LT
38x13.50R24LT
38x14.50R17LT
38x14.50R18LT
38x14.50R20LT
38x15.50R15LT
10.00
10.00
10.00
10.00
11.00
11.00
11.00
11.50
11.00
11.50
11.50
11.50
12.50
12.50
9.00
10.00
10.00
10.00
10.00
10.00
11.00
11.00
11.00
11.00
11.00
11.00
11.00
11.50
11.00
11.00
11.00
11.00
11.50
11.50
11.50
12.50
8.00
8.50
8.50
8.50
9.00
9.50
9.50
10.00
9.50
9.50
10.00
10.00
11.00
11.00
7.50
8.00
8.00
8.00
8.50
8.50
9.00
9.00
9.00
9.50
9.50
9.50
9.50
9.50
9.00
9.50
9.50
9.50
9.50
10.00
10.00
10.00
10.50
11.00
11.00
11.00
11.50
12.00
12.00
13.00
12.00
12.50
13.00
13.00
14.00
14.00
10.00
10.50
10.50
10.50
11.00
11.00
11.50
11.50
11.50
12.00
12.00
12.00
12.00
12.50
11.50
12.00
12.00
12.00
12.50
13.00
13.00
13.00
432
457
508
559
381
457
508
381
457
381
432
457
381
508
508
381
432
457
508
559
381
432
457
508
559
610
660
381
432
508
559
610
432
457
508
381
877
877
877
877
877
877
877
877
902
902
902
902
902
902
928
928
928
928
928
928
928
928
928
928
928
928
928
928
953
953
953
953
953
953
953
953
883
883
883
883
883
883
883
883
908
908
908
908
908
908
934
934
934
934
934
934
934
934
934
934
934
934
934
934
959
959
959
959
959
959
959
959
318
318
318
318
345
345
345
367
345
367
367
367
395
395
290
318
318
318
318
318
345
345
345
345
345
345
345
367
345
345
345
345
367
367
367
395

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ANNEX 7
TYRE STANDARDS ORGANIZATIONS
The Tire and Rim Association, Inc. (TRA)
The European Tyre and Rim Technical Organisation (ETRTO)
The Japan Automobile Tyre Manufacturers' Association (JATMA)
The Tyre and Rim Association of Australia (TRAA)
South Africa Bureau of Standards (SABS)
China Association for Standardization (CAS)
Indian Tyre Technical Advisory Committee (ITTAC)
Associação Latino Americana de Pneus e Aros (Brazil) (ALAPA)

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4. CONTROL ACCURACY
Test conditions shall be maintained at their specified values, independent of perturbations
induced by the tyre and rim non-uniformity, such that the overall variability of the rolling
resistance measurement is minimized. In order to meet this requirement, the average value
of measurements taken during the rolling resistance data collection period shall be within
the accuracies stated as follows:
(a)
Tyre loading:
(i)
(ii)
For LI ≤121 ±20N or ±0.5%, whichever is greater;
For LI >121 ±45N or ±0.5% whichever is greater;
(b)
(c)
Cold inflation pressure: ±3kPa;
Surface speed:
(i)
(ii)
±0.2km/h for the power, torque and deceleration methods;
±0.5km/h for the force method;
(d)
Time:
(i)
(ii)
±0.02s for the time increments specified in Paragraph 3.13.4.5.(b) for the data
acquisition in the deceleration method in Δω/Δt form;
±0.2% for the time increments specified in Paragraph 3.13.4.5.(a) for the data
acquisition in the deceleration method in dω/dt form;
(iii) ±5% for the other time durations specified in Paragraph 3.13.

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7. TEST SURFACE ROUGHNESS
The roughness, measured laterally, of the smooth steel drum surface shall have a maximum
centreline average height value of 6.3μm.
Note: In cases where a textured drum surface is used instead of a smooth steel surface,
this fact is noted in the test report. The surface texture shall then be 180μm deep
(80 grit) and the laboratory is responsible for maintaining the surface roughness
characteristics. No specific correction factor is recommended for cases where a
textured drum surface is used.

---

Table A9/1
Coefficients for Calculation of Rim Widths
Nominal aspect ratio
H/S
Coefficients for calculation of the minimum and maximum rim width
Minimum
Maximum
70 ≤ H/S ≤ 95
0.65
0.85
50 ≤ H/S ≤ 65
0.70
0.90
H/S = 45
0.80
0.95
35 ≤ H/S ≤ 40
0.85
1.00
H/S ≤ 30
Measuring rim width code – 0.5
Measuring rim width code + 0.5
1.2. Sizes Listed in Annex 6
For the tyres whose designation is given in the first column of the tables in Annex 6 to this
Regulation, the measuring rim code width shall be deemed to be that given opposite the tyre
designation in those tables. Minimum and maximum rim width codes are given in Annex 6.
2. CLASS C2 AND CLASS C3 TYRES
2.1. Metric Sizes (excluding all sizes listed in Annex 6)
For the choice of coefficients, see Table Coefficients K , K .
Theoretical rim width (R )
The theoretical rim width, R , is equal to the product of the nominal section width, S , and
the coefficient K , (see Table Coefficients K , K ):
R = K • S
Measuring rim width code (R )
The measuring rim width, R , is equal to the product of the nominal section width, S , and
the coefficient, K (see Table Coefficients K , K ):
R = K • S rounded to the nearest standardized rim width (see column 2 Table Rim Width
Code).
The measuring rim width code is given in column 1 of the Table Rim Width Code, in the row
corresponding to the measuring rim width R .

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Table A9/3
Coefficients K , K
Nominal aspect ratio
H/S
K
K
100 to 75
0.70
0.70
70, 65
0.70
0.75
60
0.70
0.75
55
0.70
0.80
50
0.70
0.80
45
0.85
0.85
40
0.85
0.90
Minimum and maximum rim width codes
The minimum and maximum rim width codes are determined, for each nominal section
width, by multiplying the nominal section width, S , by the coefficients, CR, presented in
Table Coefficients for calculation of rim widths
minimum rim width: C • S ;
maximum rim width: C • S .
The minimum and maximum rim width codes are obtained by rounding these values to the
nearest standardized rim width in Table Rim Width Code

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Table A9/5
Measuring Rim Width Code
Nominal Section Width
Measuring Rim Width Code
7.50
6.00
8.50
7.00
9.50
7.50
10.50
8.50
11.50
9.00
12.50
10.00
13.50
11.00
14.50
11.50
15.50
12.50
16.50
13.00
17.50
14.00
18.50
15.00
19.50
15.50
Minimum and maximum rim width codes
The minimum and maximum rim width codes are determined by multiplying the nominal
section width code, S , by the factors in the table below, and rounded to the nearest
standardised rim width code.
Table A9/6
Minimum and Maximum Rim Width Coefficients
Aspect ratio
AR
Coefficients for calculation of the minimum and maximum
rim width
Minimum
Maximum
70 ≤ AR ≤ 80 0.65 0.85
AR < 70 0.70 0.90

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ANNEX 10
DECELERATION METHOD: MEASUREMENTS AND DATA PROCESSING FOR
DECELERATION VALUE APPLYING THE DIFFERENTIAL FORM dω/dt.
1. Record dependency "distance-time" of rotating body decelerated from peripheral with a
speed range such as 82 to 78km/h or 62 to 58km/h dependent on tyre class
(Paragraph 3.13.4.2., Table 40) in a discrete form (Figure 1) for a rotating body:
where:
z = f(t )
z
t
is a number of body revolutions during deceleration;
is end time of revolution number z in seconds recorded with 6 digits after zero.
Figure 1
Note 1: The lower speed of the recording range may be reduced down to 60km/h when
test speed is 80km/h and 40km/h when the test speed is 60km/h.
2. Approximate recorded dependency by continuous, monotonic, differentiable function:
2.1. Choose the value nearest to the maximum of z dividable by 4 and divide it into 4 equal parts
with bounds: 0, z (t ), z (t ), z (t ), z (t ).

---

4. Estimate the quality of approximation of measured data and its accuracy by parameters:
4.1. Standard deviation in percentages:
4.2. Coefficient of Determination
R
� 1�
�
�
�
z � z
�
�t��
�
z � z
where:
1 1
1�
n
z � z �1
2 ... n�
n � � � � � �
n
2
Note 3: The above calculations for this variant of the deceleration method for tyre rolling
resistance measurement can be executed by the computer program "Deceleration
Calculator" downloadable from the WP.29 website as well as any software which
allows the calculation of nonlinear regression.

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