Global Technical Regulation No. 16

Name:Global Technical Regulation No. 16
Description:Tyres.
Official Title:Global Technical Regulation on Tyres.
Country:ECE - United Nations
Date of Issue:2015-01-16
Amendment Level:Amendment 1 of March 8, 2017
Number of Pages:148
Vehicle Types:Bus, Car, Component, Light Truck
Subject Categories:Steering, Wheels and Tyres
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Keywords:

tyre, test, tyres, load, speed, pressure, vehicle, reference, candidate, rim, paragraph, surface, snow, temperature, width, index, means, braking, section, force, diameter, requirements, measured, inflation, average, conditions, control, table, coefficient, maximum, drum, nominal, grip, standard, set, tread, calculated, testing, method, measuring, wet, measurement, class, performance, rolling, measurements, axle, symbol, procedure, passenger

Text Extract:

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ECE/TRANS/180/Add.16/Amend.1
March 8, 2017
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

3.14. Strength test for LT/C tyres
3.15. Tubeless tyre bead unseating resistance test for LT/C tyres with rim codes of 10 or
greater
3.16. Load/speed endurance test for LT/C tyres
3.17. Endurance test for LT/C tyres
3.18. Low inflation pressure performance test for LT/C tyres
3.19. High speed performance test for LT/C tyres
3.20. Physical dimensions of LT/C tyres (From FMVSS 139)
3.21. Physical dimensions of LT/C tyres (From Regulation No. 54)
3.22. Tyre rolling resistance test
3.23. Snow performance test relative to snow tyre for use in severe snow conditions
Annexes
1. Speed symbol table
2. Load index (LI) and equivalent load capacity table
3. Nominal rim diameter code table
4. Relation between the pressure index ('psi') and the units of pressure (kPa)
5. Variation of load capacity with speed commercial vehicles tyres
6. Tyre-size designations and dimensions
7. Tyre standards organizations
8. Rolling resistance test equipment tolerances
9. Measuring rim width
10. Deceleration method - Measurements and data processing for deceleration value obtaining in
differential form dω/dt

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. This GTR was developed by the GRRF informal working group on the Tyre GTR.
9. The work on this gtr 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 Tyre GTR 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
the GTR 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 the GTR 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.
12. Tests or requirements for radial passenger car tyres required extensive harmonization
during the course of the informal working group's mandate. These newly harmonized tests
or requirements are:
(a)
(b)
(c)
High speed test;
Physical dimensions test;
Required markings.

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 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 the Regulation No. 30 test for tyres with speed symbols of T (190km/h)
and above, and to use the FMVSS 139 high speed 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 technical sponsor of the tyre gtr proposed to organize the different tests
into three modules:
For GTR compliance at least the mandatory requirement
plus either module 1 or 2 are required (compliance with
both modules is permitted).
Mandatory minimum requirement
1.1. Marking
1.2. Dimensions
1.3. Harmonized high speed safety test
1.4. Endurance/Low pressure test
1.5. Tyre Wet Grip adhesion
Module 1 – Permissive requirement
2.1. Plunger energy test
2.2. Bead unseating test
Module 2 – Permissive requirement
3.1. Tyre rolling sound

23A. However, since the GTR contains only technical prescriptions and no legal aspects
concerning implementation of this GTR in national/regional legislation of the Contracting
Parties to the 1998 Agreement, irrespectively to the above described module concept, only
a Contracting Party decides how to transpose the gtr provisions into its national/regional
legislation. In order to facilitate the transposition process it may be recommended to apply a
stepwise approach and for the first stage to select just those provisions and test methods of
the GTR, which mostly suit the regulatory needs of a Contracting Party, and to consider,
when introducing new performance requirements, the possible trade-offs with the other
performances. For example, when adopting rolling resistance provisions together with wet
grip provisions attention to be put to make sure that one performance is not optimized at the
expense of the other. Meanwhile, it is anticipated that a Contracting Party will allow access
to its internal market for tyres complying with the provisions of the gtr that the Contracting
Party has not adopted if such tyres are in compliance with national/regional legislation of
that Contracting Party.
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 radial and 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 plan to change the currently assigned 2 digit plant
codes to 3 digits. A symbol, the number "1" for example, will be reserved to precede all
current 2-digit codes, and be used exclusively for existing plant codes. The "1" would only
be 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 the GTR.
26. The aim of the tyre gtr is to introduce the universal worldwide harmonized requirements to
tyres included into the scope of the gtr. In accordance with the provisions of the 1998
Agreement, once the gtr is adopted, those Contracting Parties voting in favour of its
adoption will start the process of transposing those requirements into their national
legislation.
26A. In the interests of moving rapidly towards creating a "global tyre" approach the informal
group suggests that Contracting Parties transpose the gtr requirements in a flexible way to
permit tyres complying with the full requirements access to as many markets as possible. In
a case when a test procedure includes several options, a Contracting Party may select the
option(s) at its discretion.
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.
So this gtr 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.
28. It is anticipated that the Contracting Parties will incorporate the provisions of the GTR into
regulations within their legal framework. This may include applying suitable tyre marking and
so help provide for market recognition between the Contracting Parties of tyres complying
with the provisions of this GTR. Such an approach might encourage wider recognition of
harmonized markings and thus further the move towards a single global marking where
tyres meet the full requirements established by this GTR.

34. Safety benefits resulting from the transposition of the GTR in the national legislations
depend on the previous level of the national regulations.
F. POTENTIAL COST EFFECTIVENESS
35. It is not possible to assess, at this moment, the total costs linked to the GTR. On one hand,
there are more tests in the GTR than in the existing national or international regulations; on
the other hand the harmonization of the regulation will reduce the global cost of type
approval in the variety of countries which will apply the GTR through that administration
procedure.
36. Safety benefits are anticipated, but it is not yet possible to assess them in terms of reduction
of number of accidents and victims.

2.9. "Brand name, Trade name or Trade mark" means an identification applied to
the tyre which may be the name or mark of the manufacturer or of a customer for
whom the manufacturer is producing tyres for subsequent resale (that is, "Own
Branding");
2.10. "Candidate tyre(s)" means a tyre or a tyre set that is tested for the purpose of
calculating its wet or snow grip index.
2.11. "Capped inflation" means the process of inflating the tyre and allowing the
inflation pressure to build up as the tyre is warmed up while running;
2.12. "Carcass" means that part of the pneumatic tyre structure other than the tread
and sidewall rubber, which, when inflated, bears the load;
2.13. "Chunking" means the breaking away of pieces of the tread or sidewall;
2.14. "Class C1 tyres" means tyres designed primarily for vehicles of Category 1-1 of
Special Resolution No. 1;
2.15. "Class C2 tyres" means tyres designed primarily for vehicles of Categories 1-2
and 2 of Special Resolution No. 1 with a load index in single formation ≤121 and
the speed symbol ≥"N";
2.16. "Class C3 tyres" means tyres designed primarily for vehicles of Category 2 of
Special Resolution No. 1 with a load index in single formation ≤121 and the
speed symbol ≤"M", or with a load index in single formation ≥122;
2.17. "Control tyre" means a normal production tyre that is used to establish the wet
grip or snow grip performance of tyre sizes unable to be fitted to the same
vehicle as the standard reference test tyre;
2.11. "Cord" means the strands or filaments of material forming the plies of the tyre
structure;
2.12. "Cord separation" means the parting of cords from adjacent rubber
compounds;
2.20. "Coupling (hitch) height" means the height when measured perpendicularly
from the centre of the articulation point of the trailer towing coupling or hitch to
the ground, when the towing vehicle and trailer are coupled together. The vehicle
and trailer shall be standing on level pavement surface in its test mode complete
with the appropriate tyre(s) to be used in the particular test;
2.21. "CP tyre" means a commercial vehicle tyre for service on motor caravans;
2.22. "Cracking" means any parting within the tread, sidewall or inner liner of the tyre
which may or may not extend to cord material;
2.23. "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;

2.36. "Measurement reproducibility σ " means the capability of a machine to
measure rolling resistance ;
2.37. "Maximum application load capacity" means the maximum mass a tyre can
support in a specific application, and is dependent on the speed symbol of the
tyre, the maximum design speed of the vehicle on which the tyre is fitted, the
inflation pressure and the camber angle of the wheels of the vehicle;
2.38 "Maximum load rating" means the load corresponding to the load index;
2.39. "Maximum permissible inflation pressure" means the maximum cold inflation
pressure to which the tyre may be inflated;
2.40. "Mean fully developed deceleration ("mfdd")" means the average
deceleration calculated on the basis of the measured distance recorded when
decelerating a vehicle between two specified speeds;
2.41. "Measuring rim" means an actual rim of specified width as defined by one of
the standards organizations as specified in Annex 7, on which the tyre is fitted for
measuring the physical dimensions;
2.42. "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);
2.43. "Nominal section width" shall be indicated in millimetres, and this part of the
designation shall end in either the number zero or five, so that in any single
series of tyres with the same nominal aspect ratio, the values shall all end in "0"
or they shall all end in "5";
2.44. "Normal tyre" means a tyre intended for normal on-road use;
2.45. "Open splice" means any parting at any junction of tread, sidewall, or inner liner
that extends to cord material;
2.46. "Outer diameter" means the overall diameter of an inflated new tyre;
2.47. "Overall width" means the linear distance between the outsides of the sidewalls
of an inflated pneumatic tyre, including elevations due to labelling (marking),
decorations, and/or protective bands or ribs;
1 ⎛ 1 ⎞
σm = ⋅ ⎜

1
∑ Cr − ⋅
− ⎜ ∑Cr
n
n ⎟



2.56. "PSI index" is a code identifying the inflation pressure which may be used
during testing of tyres as shown in Annex 4;
2.57. "Radial ply tyre" means a pneumatic tyre structure in which the ply cords that
extend to the beads are laid at substantially 90° to the centreline of the tread, the
carcass being restrained by circumferential belts of two or more layers of
substantially inextensible cord material;
2.58. "Rim" means that part of the wheel forming the support for the tyre and on
which the tyre beads are seated;
2.59. "Rim protector" means a feature (for example: a protruding circumferential
rubber rib) incorporated into the lower sidewall area of the tyre which is intended
to protect the rim flange from damage;
2.60. "Rolling resistance coefficient Cr" means the ratio of the rolling resistance to
the load on the tyre ;
2.61. "Rolling resistance Fr" means the loss of energy (or energy consumed) per
unit of distance traveled ;
2.62. "Run flat tyre" or "Self-supporting tyre" describes a pneumatic tyre structure
provided with any technical solutions (for example, reinforced sidewalls, etc.)
allowing the pneumatic 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;
2.63. "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;
2.64. "Secondary grooves" means the supplementary grooves of the tread pattern
which may disappear in the course of the tyre's life;
2.65. "Section height" means a distance equal to half the difference between the
outer diameter of the tyre and the nominal rim diameter;
2.66. "Section width" means the linear distance between the outside of the sidewalls
of an inflated pneumatic tyre, excluding elevations due to labelling (marking),
decoration or protective band or ribs;
2.67. "Service description" means the association of the load index or indices with a
speed symbol (for example, 91H or 121/119S);
2.68. "Sidewall" means that portion of a tyre between the tread and the bead;
.

2.78. "Structure" means the technical characteristics of the tyre's carcass (for
example: radial, bias-belted, bias ply, etc.);
2.79. "SRTT14" means the ASTM E 1136-93 (Reapproved 2003), Standard
Specification for a Radial Standard Reference Test Tire P195/75R14.
2.80. "SRTT16" means the ASTM F 2493-08, Standard Specification for a Radial
Standard Reference Test Tire P225/60R16.
2.81. "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;
2.82. "Test rim" means the rim on which a tyre is fitted for testing and which may be
any rim listed in industry standards as appropriate for use with that tyre;
2.83. "Test run" means a single pass of a loaded tyre over a given test track surface;
2.84. "Test tyre(s)" means a candidate tyre, a reference tyre or a control tyre or tyre
set that is used in a test run;
2.85. "Theoretical rim" means a rim width calculated by multiplying the nominal
section width by a specific, industry standardized, coefficient depending upon the
aspect ratio of the tyre;
2.86. "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;
2.87. "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.
2.88. "Tread" means that part of a tyre that comes into contact with the road;
2.89. "Tread pattern groove" means the space between two adjacent ribs or blocks
in the tread pattern;
2.90. "Tread depth" means the depth of the principal grooves;
2.91. "Tread pattern" means the geometric arrangement of blocks, ribs and grooves
of the tread;
2.92. "Tread separation" means the pulling away of the tread from the tyre carcass;

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., pneumatic 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 six 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.

3.3.5.
In the case of LT or C type 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 and C type tyres rated for single fitmentt only, mark as follows
"Max load ___kg (___lb) at ___kPa (___psi) cold".
3.3.6.
3.3.7.
3.3.8.
3.3.9.
The inscription "EXTRA LOAD" or "XL" for extra load tyres, or the inscription "LL"
or "LIGHT
LOAD" for light load tyres, if applicable, in characters nott less than
4mm high;
The word "TUBETYPE", if applicable, in characters not lesss than 4mm high;
The inscription "M+S", "M.S.", "M&S", "M-S", or "M/S", in characters not less
than 4mmm high, if the tyre is a snow
tyre.
The "Alpine" symbole ("3-peaked mountain snowflake") which identifies a snow
tyre that classified as "snow tyre for use in severe snow conditions". The symbol
shall have
a minimumm base of 15mm and a minimum m height of 15mmm and shall
contain three peaks with the middle peak being the tallest. Inside the mountain,
there shall be asix-sided snowflake having a minimum height of one-half the
tallest peak. An example is shown below, and is to be placed adjacent to an
inscriptionn as listed in Paragraph 3.3.8.
3.3.10.
The symbol below iff the tyre is a "run flat" or "self-supportingare
met as per Paragraph 3.13.,
tyre, and
performance requirements for run flat tyres
where "h" is at least 12mm.

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 height of each tread wear indicator shall be 1.6mm, + 0.6 - 0.0mm.
3.5. Physical Dimensions of Passenger Car Tyres
3.5.1. The following paragraphs describe in detail the requirements for determining the
physical dimensions of pneumatic tyres according to this Regulation. The
characteristics to be determined are the overall width, and the outside diameter.
If these characteristics are within the specified tolerances, the physical
dimensions of the tyre are acceptable.
3.5.2. Definitions (see Paragraph 2. of this Regulation for detailed definitions of various
terms)
3.5.2.1. The overall width of the tyre is defined as the average of four measurements of
its width at the widest point, including any markings or protective ribs.
3.5.2.2. There is no defined theoretical overall width of standard tyres. It is a measured
characteristic, not a calculated one.
3.5.3. The theoretical section width shall be calculated by the following formula:
Where:
S = S + K(A - A ),
S
S
A
A
A
is the theoretical section width expressed in mm;
is the nominal section width (in mm) as shown on the side wall of the tyre in
the designation of the tyre as prescribed;
is the width (expressed in mm) of the measuring rim, as declared by the
manufacturer;
is the width (expressed in mm) of the theoretical rim.
shall be taken to equal S multiplied by the factor x, as specified in the
international standard ISO 4000-1, and K shall be taken to equal 0.4.

3.5.5.7. 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
millimetre.
3.5.6. Physical Dimension Requirements
3.5.6.1. Overall Width
3.5.6.1.1. The tyre overall width may exceed the theoretical section width defined in
Paragraph 3.5.3. above by 4%.
3.5.6.1.2. In addition, if the tyre has rim protectors (see definition in Paragraph 2.), the
figure as increased by the above tolerance may be exceeded by 8mm.
3.5.6.2. Outer Diameter
3.5.6.2.1.
The outer diameter of a tyre shall not be outside the values D
and D
obtained from the following formulae:
Where the coefficients "a" and "b" are:
coefficient "a" = 0.97
D = d + (2H a)
D = d + (2H b)
coefficient "b" = 1.04 for normal (road type) and 1.06 for special use tyres
For snow tyres the maximum overall diameter (D ) may be exceeded by 1%.

3.6.2. Strength Test Procedure
3.6.2.1. Mount the tyre on a test rim and inflate it to the test inflation pressure specified in
the Table below:
Strength test tyre
inflation pressures
Tyre application
Test pressure (kPa)
Standard load, light load
180
Extra load
220
3.6.2.2. Condition the wheel and tyre assembly for at least 3h at the temperature of the
test room;
3.6.2.3. Re-adjust the tyre pressure to that specified in the previous table above
(Paragraph 3.6.2.1.);
3.6.2.4. Force a 19mm (3/4in) 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 50mm (2in) per minute;
3.6.2.5. Record the force and penetration at five test points equally spaced around the
circumference of the tyre. If the tyre fails to break before the plunger is stopped
by reaching the rim, record the force and penetration as the rim is reached and
use these values in Paragraph 3.6.2.6.
3.6.2.6. The breaking energy, W, in Joules, shall be calculated from:
Where:
W = ((F P)/2) 10
W
F
P
= Energy in Joules
= Force in Newtons applied to the plunger
= Penetration of the plunger in mm
or
W = (F P)/2
Where:
W
F
P
= Energy in inch-pounds
= Force in pounds and
= Penetration in inches.
3.6.2.7. Determine the breaking energy value for the tyre by computing the average of
the five values obtained.

3.7.3.3.
3.7.3.4.
3.7.3.5.
Apply a force through the block to the tyre outer sidewall att a rate of 50mm/min ±
2.5mm/min.
Increase the t force until the bead unseats or until u the prescribed value
shown in
Paragraph
3.7.1.2. is reached.
Repeat the test at least four times at places approximately equally spaced
around the
tyre circumference.
Figure 2
Bead Unseating Fixture F
Table 1
List of "A" Dimensions
Rim code
20
19
18
17
16
15
14
Table of A dimension for different rim codes
mm
345
330
318
305
292
279
267
Inches
13.50
13.00
12.50
12.00
11.50
11.00
10.50

3.8. Tyre Rolling Sound Emission Test
3.8.1. Requirements
Figure 4
Bead Unseating Block
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 ≤0 (or
≤254mm) or ≥25 (or ≥635mm) the rolling sound emission value shall not exceed
the values given below for tyres of Classes C1, C2 and C3, 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.

3.8.3. Measuring Instruments
3.8.3.1. Acoustic Measurements
3.8.3.1.1. 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 standard
IEC 60651: 1979/A1:1993, second edition.
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
standard IEC 60942:1988.
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.
3.8.3.1.2. Compliance with requirements
The compliance of the sound calibration device with the requirements of
standard IEC 60942:1988 shall be verified once a year and the compliance of
the instrumentation system with the requirements of standard IEC
60651:1979/A1:1993, second edition shall be verified at least every two years,
by a laboratory which is authorized to perform calibrations traceable to the
appropriate standards.
3.8.3.1.3. Positioning of the microphone
The microphone (or microphones) shall be located at a distance of 7.5 ± 0.05m
from track reference line CC' (Figure 5) and 1.2 ± 0.02m above the ground. Its
axis of maximum sensitivity shall be horizontal and perpendicular to the path of
the vehicle (line CC').
3.8.3.2. Speed Measurements
The vehicle speed shall be measured with instruments with accuracy of ±1km/h
or better when the front end of the vehicle has reached line PP' (Figure 5).
3.8.3.3. Temperature Measurements
Measurements of air as well as test surface temperature are mandatory.
The temperature measuring devices shall be accurate within ±1°C.

3.8.4.2. Meteorological Conditions
3.8.4.3. 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.
3.8.4.3.1. 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.
3.8.4.3.2. 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.
3.8.4.4. Test Vehicle Requirements
3.8.4.4.1. General
3.8.4.4.2. Vehicle load
3.8.4.4.3. Wheelbase
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 3.8.4.5.2. below.
The wheelbase between the two axles fitted with the test tyres shall for Class C1
be less than 3.50m and for Class C2 and Class C3 tyres be less than 5m.
3.8.4.4.4. Measures to minimize vehicle influence on sound level measurements
3.8.4.4.4.1. Requirements:
To ensure that tyre rolling sound is not significantly affected by the test vehicle
design the following requirements and recommendations are given.
(a)
(b)
(c)
(d)
Spray suppression flaps or other extra device to suppress spray shall not
be fitted;
Addition or retention of elements in the immediate vicinity of the rims and
tyres, which may screen the emitted sound, is not permitted;
Wheel alignment (toe in, camber and caster) shall be in full accordance
with the vehicle manufacturer's recommendations;
Additional sound absorbing material may not be mounted in the wheel
housings or under the underbody;

3.8.4.5.3. Tyre Inflation Pressure
Each tyre fitted on the test vehicle shall have a test pressure P not higher than
the reference pressure P and within the interval:
P
⎛ Q
× ⎜

⎝ Q




≤ P
≤ 1.1P
⎛ Q
× ⎜

⎝ Q




For Class C2 and Class C3 the reference pressure P is the pressure
corresponding to the pressure index marked on the sidewall.
For Class C1 the reference pressure is P = 250kPa for "standard" or "light load"
tyres and 290kPa for "extra load" tyres; the minimum test pressure shall be
P = 150kPa.
3.8.4.5.4. 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.
3.8.5. Method of Testing
3.8.5.1. General Conditions
For all measurements the vehicle shall be driven in a straight line over the
measuring section (AA' to BB') in such a way that the median longitudinal plane
of the vehicle is as close as possible to the line CC'.
When the front end of the test vehicle has reached the line AA', the vehicle's
driver shall have put the gear selector on neutral position and switched off the
engine. If abnormal noise (e.g. ventilator, self-ignition) is emitted by the test
vehicle during the measurement, the test shall be disregarded.
3.8.5.2. Nature and Number of Measurements
The maximum sound level expressed in A-weighted decibels (dB(A)) shall be
measured to the first decimal place as the vehicle is coasting between lines AA'
and BB' (Figure 5 - front end of the vehicle on line AA', rear end of the vehicle on
line BB'). This value will constitute the result of the measurement.
At least four measurements shall be made on each side of the test vehicle at test
speeds lower than the reference speed specified in Paragraph 3.8.6.1. and at
least four measurements at test speeds higher than the reference speed. The
speeds shall be approximately equally spaced over the speed range specified in
Paragraph 3.8.5.3.

3.8.6.3. Temperature Correction
For Class C1 and Class C2 tyres, the final result shall be normalized to a test
surface reference temperature ϑref by applying a temperature correction,
according to the following:
Where:
LR(ϑref) = LR(ϑ) + K(ϑref - ϑ)
ϑ = the measured test surface temperature
ϑref = 20°C.
For Class C1 tyres, the coefficient K is:
-0.03dB(A)/°C when ϑ >ϑref and
-0.06dB(A)/°C when ϑ <ϑref.
For Class C2 tyres, the coefficient K is -0.02dB(A)/°C.
If the measured test surface temperature does not change more than 5°C within
all measurements necessary for the determination of the sound level of one set
of tyres, the temperature correction may be made only on the final reported tyre
rolling sound level as indicated above, utilizing the arithmetic mean value of the
measured temperatures. Otherwise each measured sound level Li shall be
corrected, utilizing the temperature at the time of the sound recording.
3.8.6.4. In order to take account of any measuring instrument inaccuracies, the results
according to Paragraph 3.8.6.3. shall be reduced by 1dB(A).
3.8.6.5. The final result, the temperature corrected tyre rolling sound level LR(ϑref) in
dB(A), shall be rounded down to the nearest lower whole value.

3.9.2. Preparation of Tyre
Mount the tyre on a test rim and inflate it to the pressure specified in the table
below.
Endurance test tyre inflation
pressures
Tyre application
Test pressure (kPa)
Standard load, light load
180
Extra load
220
3.9.2.1. Condition the assembly at 35 ± 3°C for not less than 3h.
3.9.2.2. Readjust the pressure to the value specified in the table in Paragraph 3.9.2.
immediately before testing.
3.9.3. Test Procedure
3.9.3.1. Mount the assembly on a test axle and apply a load as given in
Paragraph 3.9.3.3. below to load it against the outer face of a smooth wheel
having a diameter of 1.7m ± 1%.
3.9.3.2. During the test the ambient temperature, at a distance of not less than 150mm
and not more than 1m from the tyre, is maintained at 35 ± 3°C.
3.9.3.3. 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:
Passenger car tyres:
Test period Duration Load as a percentage of tyre maximum load capacity
1 4h 85%
2 6h 90%
3 24h 100%
3.9.3.4. 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.
3.9.3.5. 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. above.

3.10.3.4. Throughout the test, the inflation pressure is not corrected and the test load is
maintained at the initial level.
3.10.3.5. During the test, the ambient temperature, at a distance of not less than 150mm
and not more than 1m from the tyre, is maintained at 35 ± 3°C.
3.10.3.6. Allow the tyre to cool for between 15 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 3.10.1.1. above.
3.11. High Speed Performance Test for Passenger Car Tyres
3.11.1. Requirements
When the tyre is tested in accordance with Paragraph 3.11.3. or 3.11.5.;
3.11.1.1. There shall be no visible evidence of tread, sidewall, ply, cord, inner liner, belt or
bead separation, chunking, open splices, cracking or broken cords. For tyres
tested at a speed of 300km/h (speed symbol "Y") or above, superficial blistering
in the tyre tread due to localized heat build-up in the test drum is acceptable.
3.11.1.2. 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.
3.11.1.3. The outer diameter of the tyre, measured 2h after the load/speed performance
test, shall not differ by more than ±3.5% from the outer diameter as measured
before the test.
3.11.1.4. For tyres identified by means of letter code "ZR" within the size designation and
suitable for speeds over 300km/h, the above high speed test is carried out on
one tyre at the load and speed conditions marked on the tyre. Another
load/speed test shall be carried out on a second sample of the same tyre type at
the load and speed conditions specified as maximum by the tyre manufacturer.
The second test may be carried out on the same tyre sample.
3.11.2. Preparation of the tyres with speed symbols "F" to "S" as specified in Annex 1 to
this Regulation.
3.11.2.1. Mount the tyre on a test rim and inflate it to the appropriate pressure specified in
the Table below:
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 load
corresponding to the load
index

3.11.4.2. Inflate it to the appropriate pressure as given (in kPa) in the Table below:
Inflation Pressure and Test Load
Speed symbol
Inflation pressure, kPa
Standard load tyres,
light load tyres
Extra load
tyres
Test load
T, U, H
280
320
V
300
340
W
320
360
Y
320
360
80 % of the load corresponding to the
load index
73% of the load corresponding to the
load index
68% of the load corresponding to the
load index
68% of the load corresponding to the
load index
3.11.4.3. Condition the tyre and wheel assembly at between 20°C and 30°C for not less
than 3h.
3.11.4.4. Re-adjust the tyre pressure to that specified in Paragraph 3.11.4.2. above.
3.11.5. Test procedure for tyres with speed symbols "T" to "Y" as specified in Annex 1 to
this Regulation.
3.11.5.1. Press the assembly against the outer face of 1.7m ± 1% or 2.0m ± 1% test drum.
3.11.5.2. Depending upon the speed symbol applicable to the tyre, apply a load to the test
axle equal to that shown in the table in Paragraph 3.11.4.2. above.
3.11.5.3. Throughout the test the tyre pressure shall not be corrected and the test load
shall be kept constant.
3.11.5.4. 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 desires to increase
test severity.
3.11.5.5. Carry the test through, without interruptions as follows, in relation to the tyre's
speed symbol.
3.11.5.6. The initial test speed (ITS) is equal to the tyre's speed symbol:
(a)
(b)
Less 40km/h on a 1.70m ± 1% drum, or
Less 30km/h on a 2.0m ± 1% drum.

3.12. Test for Adhesion Performance on Wet Surfaces
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:
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:
Category of use
Wet grip index (G)
Other
Traction
tyres
Normal tyre ≥0.95 ≥0.85
Snow tyre
Snow tyre for use in severe snow
conditions
≥0.95 ≥0.85
≥0.85 ≥0.85
Special use tyre ≥0.85 ≥0.85

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 60 BPN
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 degrees Celsius.
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%.
3.12.2.2.2.2. ASTM E 1136 Standard Reference Test Tyre Method (b)
This method uses the reference tyre that has the characteristics indicated in the
ASTM E 1136-93 (Reapproved 2003) and referred to as SRTT14.
The average peak braking force coefficient (μ
0.7 ± 0.1 at 65km/h.
) of the SRTT14 shall be
The average peak braking force coefficient (μ ) of the SRTT14 shall be
corrected for the wetted road surface temperature as follows:
Peak braking force coefficient (μ
(measured) + temperature correction
) = peak braking force coefficient
Temperature correction = 0.0035 × (t - 20)
Where t is the wetted road surface temperature in degrees Celsius.

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
3.12.2.3.1.4. Tyres and rims
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 ± 0.5mm, 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.
3.12.2.3.1.4.1. Tyre preparation and break-in
3.12.2.3.1.4.2. Tyre load
The test tyres shall be trimmed to remove all protuberances on the tread surface
caused by mould air vents or flashes at mould junctions.
Fit the test tyres on rims specified by a recognized tyre and rim standards
organization as listed in Annex 7.
The static load on each axle tyre shall lie between 60% and 90% of the tested
tyre load capacity. Tyre loads on the same axle should not differ by more than
10%.
3.12.2.3.1.4.3. Tyre inflation pressure
3.12.2.3.1.5. Procedure
3.12.2.3.1.5.1. Test run
On the front and rear axles, the inflation pressures shall be 220kPa (for
standard- and extra load tyres). The tyre pressure should be checked just prior to
testing at ambient temperature and adjusted if required.
The following test procedure applies for each test run.
3.12.2.3.1.5.1.1. The passenger car is driven in a straight line up to 85 ± 2km/h.
3.12.2.3.1.5.1.2. Once the passenger car has reached 85 ± 2km/h, the brakes are always
activated at the same place on the test track referred to as "braking starting
point", with a longitudinal tolerance of 5m and a transverse tolerance of 0.5m.

3.12.2.3.1.6. Processing of measurement results
3.12.2.3.1.6.1. Calculation of the average deceleration (AD)
The average deceleration (AD) is calculated for each valid test run in m/s as
follows:
AD =
S − S
2d
where:
S
S
d
is the final speed in m/s; S = 20km/h = 5.556m/s
is the initial speed in m/s; S = 80km/h = 22.222m/s
is the distance covered between S and S in metres.
3.12.2.3.1.6.2. Validation of results
The AD coefficient of variation is calculated as follows:
(Standard Deviation/Average) × 100.
For the reference tyres (R): If the AD coefficient of variation of any two
consecutive groups of three tests runs of the reference tyre set is higher than
3%, all data should be discarded and the test repeated for all test tyres (the
candidate tyres and the reference tyres).
For the candidate tyres (T): The AD coefficients of variation are calculated for
each candidate tyre set. If one coefficient of variation is higher than 3%, the data
should be discarded and the test repeated for that candidate tyre set.

3.12.2.3.1.6.5. Calculation of the wet grip index of the candidate tyre
The wet grip index of the candidate tyre (G(T)) is calculated as follows:
where:
G(T)
⎡BF (T)
= ⎢ ⋅ 125 + a ⋅
⎢⎣
BF (R)
⎛ BF (R)

⎝ BF (R )
⎞⎤
⎟⎥
⎠⎥⎦
( t − t ) + b ⋅ ⎜ − 1.0⎟
⋅ 10
t
t
is the measured wet surface temperature in degree Celsius when the
candidate tyre (T) is tested
is the wet surface reference temperature condition, t = 20°C for normal
tyres and t = 10°C for snow tyres
BFC(R ) is the braking force coefficient for the reference tyre in the reference
conditions, BFC(R ) = 0.68
a = -0.4232 and b = -8.297 for normal tyres, a = 0.7721 and b = 31.18 for snow
tyres [a is expressed as (1°C)]
3.12.2.3.1.7. Wet grip performance comparison between a candidate tyre and a reference tyre
using a control tyre
3.12.2.3.1.7.1. General
Where the candidate tyre size is significantly different from that of the reference
tyre, a direct comparison on the same instrumented passenger car may not be
possible. This testing method uses an intermediate tyre, hereinafter called the
control tyre as defined in Paragraph 2.5.
3.12.2.3.1.7.2. Principle of the approach
The principle is the use of a control tyre set and two different instrumented
passenger cars for the test cycle of a candidate tyre set in comparison with a
reference tyre set.
One instrumented passenger car is fitted with the reference tyre set followed by
the control tyre set, the other with the control tyre set followed by the candidate
tyre set.
The specifications listed in Sections 4.1.2. to 4.1.4. apply.
The first test cycle is a comparison between the control tyre set and the
reference tyre set.
The second test cycle is a comparison between the candidate tyre set and the
control tyre set. It is done on the same test track and during the same day as the
first test cycle. The wetted surface temperature shall be within ±5°C of the
temperature of the first test cycle. The same control tyre set shall be used for the
first and the second test cycles.

3.12.2.3.2.2. Equipment
3.12.2.3.2.2.1. Tow vehicle and trailer or tyre test vehicle
The tow vehicle or the tyre test vehicle shall have the capability of maintaining
the specified speed of 65 ± 2km/h even under the maximum braking forces.
The trailer or the tyre test vehicle shall be equipped with one place where the
tyre can be fitted for measurement purposes hereafter called 'test position' and
the following accessories:
(a)
(b)
(c)
Equipment to activate brakes in the test position;
A water tank to store sufficient water to supply the road surface wetting
system, unless external watering is used;
Recording equipment to record signals from transducers installed at the
test position and to monitor water application rate if the self-watering
option is used.
The maximum variation of toe-settings and camber angle for the test position
shall be within ±0.5° with maximum vertical load. Suspension arms and bushings
shall have sufficient rigidity necessary to minimize free play and ensure
compliance under application of maximum braking forces. The suspension
system shall provide adequate load-carrying capacity and be of such a design as
to isolate suspension resonance.
The test position shall be equipped with a typical or special automotive brake
system which can apply sufficient braking torque to produce the maximum value
of braking test wheel longitudinal force at the conditions specified.
The brake application system shall be able to control the time interval between
initial brake application and peak longitudinal force as specified in
Paragraph 3.12.2.3.2.7.1.
The trailer or the tyre test vehicle shall be designed to accommodate the range
of candidate tyre sizes to be tested.
The trailer or the tyre test vehicle shall have provisions for adjustment of vertical
load as specified in Paragraph 3.12.2.3.2.5.2.

3.12.2.3.2.4. Wetting conditions
3.12.2.3.2.5. Tyres and rims
The tow vehicle and trailer or the tyre test vehicle may be optionally equipped
with a pavement-wetting system, less the storage tank, which, in the case of the
trailer, is mounted on the tow vehicle. The water being applied to the pavement
ahead of the test tyres shall be supplied by a nozzle suitably designed to ensure
that the water layer encountered by the test tyre has a uniform cross section at
the test speed with a minimum splash and overspray.
The nozzle configuration and position shall ensure that the water jets are
directed towards the test tyre and pointed towards the pavement at an angle of
20° to 30°.
The water shall strike the pavement 250mm to 450mm ahead of the centre of
tyre contact. The nozzle shall be located 25mm above the pavement or at the
minimum height required to clear obstacles which the tester is expected to
encounter, but in no case more than 100mm above the pavement.
The water layer shall be at least 25mm wider than the test tyre tread and applied
so the tyre is centrally located between the edges. Water delivery rate shall
ensure a water depth of 1.0 ± 0.5mm and shall be consistent throughout the test
to within ±10%. The volume of water per unit of wetted width shall be directly
proportional to the test speed. The quantity of water applied at 65km/h shall be
18l/s per metre of width of wetted surface in case of a water depth of 1.0mm.
3.12.2.3.2.5.1. Tyre preparation and break-in
3.12.2.3.2.5.2. Tyre load
The test tyres shall be trimmed to remove all protuberances on the tread surface
caused by mould air vents or flashes at mould junctions.
The test tyre shall be mounted on the test rim declared by the tyre manufacturer.
A proper bead seat should be achieved by the use of a suitable lubricant.
Excessive use of lubricant should be avoided to prevent slipping of the tyre on
the wheel rim.
The test tyres/rim assemblies shall be stored in a location for a minimum of 2h
such that they all have the same ambient temperature prior to testing. They
should be shielded from the sun to avoid excessive heating by solar radiation.
For tyre break-in, at least two braking runs shall be performed under the load,
pressure and speed as specified in Paragraphs 3.12.2.3.4.2.5.2, 3.12.2.3.4.2.5.3
and 3.12.2.3.4.2.7.1 respectively.
The test load on the test tyre is 75 ± 5% of the tyre load capacity.

3.12.2.3.2.7.2. Test cycle
A number of test runs are made in order to measure the wet grip index of the
candidate tyre (T) according to the following procedure, whereby each test run
shall be made from the same spot on the test track and in the same direction. Up
to three candidate tyres may be measured within the same test cycle, provided
that the tests are completed within one day.
3.12.2.3.2.7.2.1. First, the reference tyre is tested.
3.12.2.3.2.7.2.2. After at least six valid measurements are performed in accordance with
Paragraph 3.12.2.3.2.7.1. the reference tyre is replaced by the candidate tyre.
3.12.2.3.2.7.2.3. After six valid measurements of the candidate tyre are performed, two more
candidate tyres may be measured.
3.12.2.3.2.7.2.4. The test cycle is closed by six more valid measurements of the same reference
tyre as at the beginning of the test cycle.
Examples:
(a)
The run order for a test cycle of three candidate tyres (T1 to T3) plus the
reference tyre (R) would be the following:
R-T1-T2-T3-R
(b)
The run order for a test cycle of five candidate tyres (T1 to T5) plus the
reference tyre R would be the following:
3.12.2.3.2.8. Processing of measurement results
R-T1-T2-T3-R-T4-T5-R
3.12.2.3.2.8.1. Calculation of the peak braking force coefficient
The tyre peak braking force coefficient (μ ) is the highest value of μ(t) before
lockup occurs calculated as follows for each test run. Analogue signals should be
filtered to remove noise. Digitally recorded signals must be filtered using a
moving average technique.
where:
μ ( t) =
fh(t)
fv(t)
μ(t)
is the dynamic tyre braking force coefficient in real time;
fh(t) is the dynamic braking force in real time, in N;
fv(t) is the dynamic vertical load in real time, in N.

3.12.2.3.2.8.4. Calculation of the average peak braking coefficient (μ )
The average value of the peak braking coefficients (μ ) is calculated
according to Table 4 whereby Ta (a = 1, 2 or 3) is the average of the peak
braking force coefficients measured for one candidate tyre within one test cycle.
Table 4
Test tyre μ
Reference tyre μ (R) = Ra as per Table 3
Candidate tyre μ (T) = Ta
3.12.2.3.2.8.5. Calculation of the wet grip index of the candidate tyre
The wet grip index of the candidate tyre (G(T)) is calculated as follows:
⎡ μ
G(T) = ⎢
⎢μ

(T)
(R)

125

a

(t

t
) + b ⋅
⎛ μ


μ
(R)
(R )
⎞⎤
− 1.0⎟⎥
⎠⎥⎦

10
where:
t
t
is the measured wet surface temperature in degree celsius when the
candidate tyre (T) is tested
is the wet surface reference temperature condition
t = 20°C for normal tyres t = 10°C for snow tyres
μ (R ) = 0.85 is the peak braking force coefficient for the reference tyre in
the reference conditions
a = -0.4232 and b = -8.297 for normal tyres, a = 0.7721 and b = 31.18 for snow
tyres" [a is expressed as (1°C)]
3.12.3. C2 and C3 Category 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.

3.12.3.1.2. The surface may be wetted from the track-side or by a wetting system
incorporated into the test vehicle or the trailer.
If a track-side system is used, the test surface shall be wetted for at least half an
hour prior to testing in order to equalize the surface temperature and water
temperature. It is recommended that track-side wetting be continuously applied
throughout testing.
The water depth shall be between 0.5 and 2.0mm.
3.12.3.1.3. The wind conditions shall not interfere with wetting of the surface (wind-shields
are permitted).
The ambient and the wetted surface temperature shall be between 5°C and 35°C
and shall not vary during the test by more than 10°C.
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)
(b)
(c)
SRTT 315/70R22.5 LI=154/150, ASTM F2870
SRTT 245/70R19.5 LI=136/134, ASTM F2871
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:
For 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 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)
(b)
A trailer or special purpose tyre evaluation vehicle; or
A standard production vehicle (M , M , N , N or N , Category) as defined
in Special Resolution No. 1 concerning the common definitions of vehicule
categories, masses and dimensions (S.R.1) contained in
ECE/TRANS/WP.29/1045 and subsequent amendments.

3.12.3.2.1.2. Test procedure
3.12.3.2.1.2.1. Fit the test tyres on rims specified by a recognized tyre and rim standards
organization as listed in Annex 7. 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:
P
= P
⎛ Q
×

⎝ Q



Where:
P = Inflation pressure marked on the sidewall. If P is not marked on the
sidewall refer to the specified pressure in applicable tyre standards
manuals corresponding to maximum load capacity for single applications
Q = The static test load of the tyre
Q = The maximum mass associated with the load index 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 value corresponding to the
load index.
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.

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 × 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 × 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:
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 T1 Ra = 1/2 (R1 + R2)
2 │ R1 – T1 – T2 – R2
T1
T2
T1
Ra = 2/3 R1 + 1/3 R2
Ra = 1/3 R1 + 2/3 R2
Ra = 3/4 R1 + 1/4 R2
3 │ R1 – T1 – T2 – T3 – R2
T2
T3
Ra = 1/2 (R1 + R2)
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).

3.12.3.2.2.2.2. Vehicle equipment
The rear axle may be indifferently fitted with two or four tyres.
For the reference tyre testing, both axles are fitted with reference tyres. (A total
of four or six reference tyres depending on the choice above mentioned).
For the candidate tyre testing, three fitting configurations are possible:
(a)
(b)
(c)
Configuration "Configuration 1": Candidate tyres on front and rear axles: it
is the standard configuration that should be used every time it is possible.
Configuration "Configuration 2": Candidate tyres on front axle and
reference tyre or control tyre on rear axle: allowed in such cases where
fitting the candidate tyre on the rear position is not possible.
Configuration "Configuration 3": Candidate tyres on rear axle and
reference tyre or control tyre on front axle: permitted in such cases where
fitting the candidate tyre on the front position is not possible.
3.12.3.2.2.2.3. Tyre inflation pressure
(a)
For a vertical load higher or equal to 75% of the load capacity of the tyre,
the test inflation pressure "P " shall be calculated as follows:
P = P · (Q /Q )
P = Inflation pressure marked on the sidewall. If P is not marked on the
sidewall refer to the specified pressure in applicable tyre standards
manuals corresponding to maximum load capacity for single
applications
Q = static test load of the tyre
Q = maximum mass associated with the load index of the tyre
(b)
For a vertical load lower than 75% of the load capacity of the tire, the test
inflation pressure P shall be calculated as follows:
P = P · (0.75) = (0.7) · P
P = Inflation pressure marked on the sidewall.
If P is not marked on the sidewall refer to the specified pressure in
applicable tyre standard manuals corresponding to maximum load
capacity for single applications.
Check the tyre pressure just prior to testing at ambient temperature.

3.12.3.2.2.2.6.2. According to the type of transmission, two cases are possible:
(a)
Manual transmission
As soon as the driver is in the measuring zone and having reached
65 ± 2km/h, the clutch is released and the brake pedal depressed sharply,
holding it down as long as necessary to perform the measurement.
(b)
Automatic transmission
3.12.3.2.2.2.6.3. Test running order
Examples:
As soon as the driver is in the measuring zone and having reached
65 ± 2km/h, select neutral gear and then the brake pedal is depressed
sharply, holding it down as long as necessary to perform the
measurement.
Automatic activation of the brakes can be performed by means of a
detection system made of two parts, one indexed to the track and one
embarked on the vehicle. In that case braking is made more rigorously at
the same portion of the track.
If any of the above-mentioned conditions are not met when a
measurement is made (speed tolerance, braking time, etc.), the
measurement is discarded and a new measurement is made.
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 tires, 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.

3.12.3.2.2.2.7.3. Calculation of the "average AD"
If R1 is the average of the AD values in the first test of the reference tyre and R2
is the average of the AD values in the second test of the reference tyre, the
following operations are performed, according to Table 1.
Ra is the adjusted average AD of the reference tyre.
Number of sets of candidate tyres
between two successive runs of the
reference tyre
Table 1
Set of candidate
tyres to be
qualified
1 R1-T1-R2 T1 Ra = 1/2 (R1 + R2)
2 R1-T1-T2-R2
T1
T2
T1
a
Ra = 2/3 R1 + 1/3 R2
Ra = 1/3 R1 + 2/3 R2
Ra = 3/4 R1 + 1/4 R2
3 R1-T1-T2-T3-R2
T2
T3
Ra = 1/2 (R1 + R2)
Ra = 1/4 R1 + 3/4 R2
3.12.3.2.2.2.7.4. Calculation of braking force coefficient, BFC
BFC(R) and BFC(T) are calculated according to Table 2:
Tyre type
Reference tyre
Candidate tyre
Table 2
g is the acceleration due to gravity (rounded to 9.81m·s ).
Braking force coefficient is
BFC(R) = Ra/g
BFC(T) = Ta/g
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 into the following table:

Figure 1
Nomenclature Explanation Related to Grip Index of the Tyre
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 2 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
3.12.3.2.2.1.2. 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.

3.13.1.4. Mount the tyre-and-wheel assembly to a test axle and press it against the outer
surface of a smooth wheel 1.70m ± 1% or 2.0m ± 1% in diameter.
3.13.1.5. Apply to the test axle a load equal to 65%of the maximum load rating
corresponding to the load index of the tyre.
3.13.1.6. At the start of the test, measure the deflected section height (Z1).
3.13.1.7. During the test the temperature of the test room shall be maintained at 35 ± 3°C.
3.13.1.8. 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.
3.13.1.9. At the end of the test, measure the deflected section height (Z2).
3.13.1.10. Calculate the change in% of the deflected section height compared to the
deflected section height at the start of the test as ((Z1 – Z2)/Z1) 100.
3.14. Strength Test for LT/C Tyres
3.14.1. Requirements
When tested according to the procedure described in this section, LT/C tyres
shall have an average strength of not less than the values shown in the Table
below:
Load range
3.14.2. Preparation of Tyre
Joules (J)
Minimum breaking energy
Inch-pounds (in-lbs)
B 293 2,600
C 361 3,200
D 514 4,550
E 576 5,100
Mount the tyre on a model rim assembly and inflate it to the pressure
corresponding to the maximum load, or maximum dual load where there is both
a single and dual load marked on the tyre. 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.

3.15. Tubeless Tyre Bead Unseating Resistance Test for LT/C Tyres with Rim
Codes of 10 or Greater
3.15.1. 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.
3.15.2. Preparation of Tyre-Wheel Assembly
3.15.2.1. Wash the tyre, dry it at the beads, and mount it without lubrication or adhesives
on a clean, painted test rim.
3.15.2.2. Inflate it to the applicable pressure specified in the following table at ambient
room temperature:
For LT/C tyres, the maximum permissible inflation pressure to be used for the
bead unseating test is as follows:
Load range
Load range C
Load range D
Load range E
Test pressure
260kPa
340kPa
410kPa
For LT/C tyres with a nominal cross section greater than 295mm (11.5in), the
maximum permissible inflation pressure to be used for the bead unseating test is
as follows:
Load range
Load range C
Load range D
Load range E
Test pressure
190kPa
260kPa
340kPa
3.15.2.3. Mount the wheel and tyre in a fixture shown in Figure 6, and force the bead
unseating block shown in Figure 7 or Figure 8 against the tyre sidewall as
required by the geometry of the fixture.

Figure 7
Diagram of Bead Unseating Block (all Dimensions in mm)
Figure 8
Diagram of Bead Unseating Block (all Dimensions in mm)

3.16.2.3. Inflate the tyre to the pressure corresponding to the pressure index specified by
the manufacturer.
3.16.2.4. Condition the tyre-and-wheel assembly at test-room temperature for not less
than 3h.
3.16.2.5. Readjust the tyre pressure to that specified in Paragraph 3.16.2.3. above.
3.16.3. Test Procedure
3.16.3.1. Mount the tyre-and-wheel assembly on the test axle and press it against the
outer face of a smooth power-driven test drum 1.70m ± 1% in diameter having a
surface at least as wide as the tyre tread.
3.16.3.2. Apply to the test axle a series of test loads expressed in% of the load carrying
capacity of the tyre, in accordance with the test programme shown in
Paragraph 3.16.4.7. below. Where the tyre has load indices for both single and
twinned utilization, the reference load for single utilization shall be taken as the
basis for the test loads.
3.16.3.3. In the case of tyres with a speed symbol Q and above, test procedures are as
specified in Paragraph 3.16.4.
3.16.3.3.1. For all other tyre types, the endurance test programme is shown in
Paragraph 3.16.4.7.
3.16.3.4. 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.
3.16.3.5. 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.
3.16.3.6 The endurance-test programme shall be carried out without interruption.
3.16.4. Load/Speed Test Programme for Tyre with Speed Symbol Q and Above
3.16.4.1. This programme applies to:
3.16.4.1.1. All tyres marked with load index in single 121 or less.
3.16.4.1.2. Tyres marked with load index in single 122 and above and with the additional
marking "C", or "LT", referred to in Paragraph 3.3.14. of this Regulation.
3.16.4.2. Load placed on the wheel as a percentage of the load corresponding to the load
index:
3.16.4.2.1. 90% when tested on a test drum 1.70m ± 1% in diameter;
3.16.4.2.2. 92% when tested on a test drum 2.0m ± 1% in diameter.
3.16.4.3. Initial test speed: speed corresponding to the speed symbol less 20km/h;
3.16.4.3.1. Time to reach the initial test speed: 10min.

3.17.2. Preparation of Tyre
3.17.2.1. Mount the tyre on a test rim and inflate it to the pressure specified for the tyre in
the following Table:
Light truck tyres with a nominal section width ≤295mm (11.5in)
Tyre application
Test pressure (kPa)
Load range C 260
Load range D 340
Load range E 410
Light truck tyres with a nominal section width >295mm (11.5in)
Load range C 190
Light truck tyres with a nominal section width ≤295mm (11.5in)
Load range D 260
Load range E 340
3.17.2.2. Condition the assembly at 35 ± 3°C for not less than 3h.
3.17.2.3. Readjust the pressure to the value specified in Paragraph 3.17.2.1. immediately
before testing.
3.17.3. Test Procedure
3.17.3.1. Mount the assembly on a test axle and press it against the outer face of a
smooth wheel having a diameter of 1.70m ± 1%.
3.17.3.2. During the test, the ambient temperature, at a distance of not less than 150mm
and not more than 1m from the tyre, is maintained at 35 ± 3°C.
3.17.3.3. Conduct the test, without interruptions, at the test speed of not less than
120km/h with loads and test periods not less than those shown in the following
Table. For snow tyres for use in severe snow conditions and marked with the
three-peaked mountain-snowflake symbol, conduct the test at not less than
110km/h.
Test period
Duration (hours)
Load as a percentage of tyre
maximum load rating
1 4 85
2 6 90
3 24 100
3.17.3.4. 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 3.17.3.3.

3.18.3. Test Procedure
3.18.3.1. The test is conducted for 90min at the end of the test specified in
Paragraph 3.17., continuous and uninterrupted, at a speed of 120km/h. For snow
tyres for use in severe snow conditions and marked with the three-peaked
mountain-snowflake symbol, conduct the test at not less than 110km/h.
3.18.3.2. Press the assembly against the outer face of a test drum with a diameter of
1.70m ± 1%.
3.18.3.3. Apply to the test axle a load equal to 100% of the tyre's maximum load carrying
capacity.
3.18.3.4. Throughout the test, the inflation pressure is not corrected and the test load is
maintained at the initial level.
3.18.3.5. During the test, the ambient temperature, at a distance of not less than 150mm
and not more than 1m from the tyre, is maintained at 35 ± 3°C.
3.18.3.6. 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 3.18.1.1., subparagraph (a).
3.19. High Speed Performance Test for LT/C Tyres
3.19.1. Requirements
3.19.1.1. When the tyre is tested in accordance with Paragraph 3.19.3.:
(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.
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 3.19.2.1.

3.20. Physical dimensions of LT/C tyres
3.20.1. Requirements
3.20.1.1. The actual section width and overall width for each tyre measured in accordance
with Paragraph 3.20.3. shall not exceed the section width specified one of the
publications described in Annex 7 to this Regulation for its size designation and
type by more than:
(a)
For tyres with a maximum permissible inflation pressure of 32, 36, or
40psi, 7%, or
(b) For tyres with a maximum permissible inflation pressure of 240, 280, 300,
340 or 350kPa, 7% or 10mm, whichever is larger.
3.20.2. Preparation of the Tyre
3.20.2.1. Mount the tyre on the measuring rim specified by the tyre manufacturer or in one
of the publications listed in Annex 7 to this Regulation.
3.20.2.2. Inflate the tyre to the pressure at maximum load as labelled on sidewall.
3.20.2.3. Condition the assembly at an ambient room temperature of 20°C to 30°C for not
less than 24h.
3.20.2.4. Readjust the tyre pressure to that specified in Paragraph 3.20.2.2.
3.20.3. Test Procedure
3.20.3.1. Measure the section width and overall width by caliper at six points
approximately equally spaced around the circumference of the tyre, avoiding
measurement of the additional thickness of the special protective ribs or bands.
The average of the measurements so obtained is taken as the section width and
overall width, respectively.
3.20.3.2. Determine the outer diameter by measuring the maximum circumference of the
tyre and dividing the figure so obtained by Pi (3.1416).

3.21.1.2.2. 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.
3.21.1.3. Tyre Section Width Specifications
3.21.1.3.1. The overall width of a tyre may be less than the section width or widths
determined pursuant to Paragraph 3.21.1.1. above.
3.21.1.3.2. It may exceed that value by 4%. However, for tyres with nominal section width
exceeding 305mm intended for dual mounting (twinning), the value determined
pursuant to Paragraph 3.21.1.1. above shall not be exceeded by more than 2%
for tyres with nominal aspect ratio higher than 60.
3.21.1.4. Tyre Outer Diameter Specifications
3.21.1.4.1.
The outer diameter of a tyre shall not be outside the values D
and D
obtained from the following formulae:
D = d + (2H × a)
D = d + (2H × b)
3.21.1.4.2. For sizes listed in Annex 6 to this Regulation the nominal section height H is
equal to:
H = 0.5 (D - d) for references see Paragraph 3.21.1.2.1.
3.21.1.4.2.1. For other sizes, not listed in Annex 6 to this Regulation
"H" and "d" are as defined in Paragraph 3.21.1.2.1
3.21.1.4.2.2. Coefficients "a" and "b" are respectively:
3.21.1.4.2.2.1. Coefficient "a" = 0.97
3.21.1.4.2.2.2. Coefficient "b"
For normal use tyres = 1.04
For special use tyres = 1.06
3.21.1.4.2.2.3.
For snow tyres the outer diameter (D
) established in conformity with the above
may be exceeded by 1%.
3.21.2. Test Procedure
3.21.2.1. The tyre is mounted on the measuring rim specified by the manufacturer and
inflated to the pressure corresponding to the pressure index specified by the
manufacturer.
3.21.2.2. The tyre fitted on its rim is conditioned to the ambient temperature of the
laboratory for at least 24h.

3.22.3. Test Equipment
3.22.3.1. Drum Specifications
3.22.3.1.1. Diameter
3.22.3.1.2. Surface
3.22.3.1.3. 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 3.22.7.3.
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 Fr and Cr 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.
3.22.3.2. Measuring Rim (see Annex 9)
The tyre shall be mounted on a steel or light alloy measuring rim, as follows:
(a)
(b)
For Class C1 tyres, the width of the rim shall be as defined in
ISO 4000-1:2010,
For Class C2 and C3 tyres, the width of the rim shall be as defined in
ISO 4209 1:2001.
In cases where the width is not defined in the above mentioned ISO Standards,
the rim width as defined by one of the standards organizations as specified in
Annex 7 may be used.
3.22.3.3. Load, Alignment, Control and Instrumentation Accuracies
Measurement of these parameters shall be sufficiently accurate and precise to
provide the required test data. The specific and respective values are shown in
Annex 8.

Table 2
Test Loads and Inflation Pressures
Tyre Class C1 C2, C3
Load-% of maximum load
capacity
Inflation pressure kPa
Standard
Load
Extra
Load
80 80
210 250
85 (% of single load)
Corresponding to maximum
load capacity for single
application
3.22.4.5. Duration and Speed.
When the deceleration method is selected, the following requirements apply:
(a)
The deceleration j shall be determined in differential dω/dt or discrete
∆ω/∆t form, where ω is angular velocity, t – time;
If the differential form dω/dt is used, then the recommendations of
Annex 10 are to be applied.
(b)
(c)
For duration ∆t, the time increments shall not exceed 0.5s;
Any variation of the test drum speed shall not exceed 1km/h within one
time increment.
3.22.5. Test Procedure
3.22.5.1. General
The test procedure steps described below shall be followed in the sequence
given.
3.22.5.2. Thermal Conditioning
The inflated tyre shall be placed in the thermal environment of the test location
for a minimum of:
(a)
(b)
3h for Class C1 tyres;
6h for Class C2 and C3 tyres.

Figure 1
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.
3.22.5.6. Measurement of Parasitic Losses
The parasitic losses shall be determined by one of the following procedures
given in Paragraph 3.22.5.6.1. or 3.22.5.6.2.

3.22.6. Data Interpretation
3.22.6.1. Determination of Parasitic Losses
3.22.6.1.1. General
The laboratory shall perform the measurements described in
Paragraph 3.22.5.6.1. for the force, torque and power methods or those
described in Paragraph 3.22.5.6.2. 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 newton
shall be calculated from the force F torque, power or the deceleration, as shown
in Paragraphs 3.22.6.1.2. to 3.22.6.1.5. below.
3.22.6.1.2. Force method at tyre spindle
Where:
Calculate: F = F (1 + r /R)
F is the tyre spindle force in newton (see Paragraph 3.22.5.6.1.),
r
R
is the distance from the tyre axis to the drum outer surface under steady
state conditions, in metre,
is the test drum radius, in meter.
3.22.6.1.3. Torque method at drum axis
Calculate: F = T /R
Where:
T is the input torque in newton meter, as determined in
Paragraph 3.22.5.6.1,
R
is the test drum radius, in metres.

Where:
I
R
is the test drum inertia in rotation, in kilogram metre squared,
is the test drum surface radius, in metre,
j is the deceleration of the test drum, without tyre, in radians per second
squared,
I
R
j
is the spindle, tyre and wheel inertia in rotation, in kilogram metre squared,
is the tyre rolling radius, in metre,
is the deceleration of unloaded tyre, in radians per second squared."
3.22.6.2. Rolling Resistance Calculation
3.22.6.2.1. General
The rolling resistance F , expressed in newton, is calculated using the values
obtained by testing the tyre to the conditions specified in this Section 3.7.3.1.
and by subtracting the appropriate parasitic losses F , obtained according to
Paragraph 3.22.6.1.
3.22.6.2.2. Force method at tyre spindle
The rolling resistance F , in newton, is calculated using the equation
Where:
F = F [1 + (r /R)] − F
F
is the tyre spindle force in newton,
F represents the parasitic losses as calculated in Paragraph 3.22.6.1.2.,
r
R
is the distance from the tyre axis to the drum outer surface under
steady-state conditions, in metres,
is the test drum radius, in metres.

3.22.6.2.5. Deceleration method
The rolling resistance Fr, in newton, is calculated using the equation:
F
I
=
R
⎛ Δω

⎝ Δt
⎞ RI
⎟ +
⎠ R
⎛ Δω

⎝ Δt

⎟ − F

Where:
ID
R
is the test drum inertia in rotation, in kilogram metre squared,
is the test drum surface radius, in metre,
F represents the parasitic losses as calculated in Paragraph 3.22.6.1.5,
∆t
is the time increment chosen for measurement, in second,
∆ω is the test drum angular speed increment, without tyre, in radian per
second,
I
R
F
is the spindle, tyre and wheel inertia in rotation, in kilogram metre squared,
is the tyre rolling radius, in metres,
is the rolling resistance, in newtons.
Or
F
=
I
R
j
RI
+
R
j
− F
Where:
I
R
is the test drum inertia in rotation, in kilogram metre squared,
is the test drum surface radius, in metres,
F represents the parasitic losses as calculated in Paragraph 3.22.6.1.5.,
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 kilogram metre squared,
is the tyre rolling radius, in metres,
is the rolling resistance, in newtons.

3.22.7.3. Drum Diameter Correction
Test results obtained from different drum diameters shall be compared by using
the following theoretical formula:
with:
F ≈ KF
K =
( R /R
)( R
+ r
)
( R
+ r
)
Where:
R
R
r
is the radius of drum 1, in metres,
is the radius of drum 2, in metres,
is one-half of the nominal design tyre diameter, in metres,
is the rolling resistance value measured on drum 1, in newtons,
F is the rolling resistance value measured on drum 2, in newtons.
3.22.7.4. Measurement Result
Where n measurements are greater than one, if required by Paragraph 3.22.5.6.,
the measurement result shall be the average of the C values obtained for the n
measurements, after the corrections described in Paragraphs 3.22.7.2. and
3.22.7.3. have been made.
3.22.7.5. The laboratory shall ensure that, based on a minimum of three measurements,
the machine maintains the following values of σ , as measured on a single tyre:
σ ≤0.075N/kN for tyres of Classes C1 and C2
σ ≤0.06N/kN for tyres of Class C3
If the above requirement for σ is not met, the following formula shall be applied
to determine the minimum number of measurements n (rounded to the
immediate superior integer value) that are required by the machine to qualify for
conformance with this Regulation.
Where:
n = (σ /x)
x = 0.075N/kN for tyres of Classes C1 and C2
x = 0.06N/kN for tyres of Class C3
If a tyre needs to be measured several times, the tyre/wheel assembly shall be
removed from the machine between the successive measurements.

3.23.1.1. Class C1, C2 and C3 Tyres
Class of tyre
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)
Snow grip index
(spin traction method)
Ref. = C1 – SRTT 14 Ref. = C2 – SRTT 16C Ref. = C1 – SRTT 14
Snow grip index
(acceleration method)
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
3.23.2. Spin Traction Method for Classes C1 and C2 Tyres (Traction Force Test).
The test procedure of ASTM standard F1805-06 shall be used to assess snow
performance through spin traction values on medium packed snow. (The snow
compaction index measured with a CTI penetrometer shall be between 70
and 80).
3.23.2.1. The test course surface shall be composed of a medium packed snow surface,
as characterized in table A2.1 of ASTM standard F1805-06.
3.23.2.2. The tyre load for testing shall be as per Option 2 in Paragraph 11.9.2. of ASTM
standard F1805-06.
3.23.3. Braking on Snow Method for Classes C1 and C2 Tyres
3.23.3.1. General Conditions
3.23.3.1.1. Test course
The braking tests shall be done on a flat test surface of sufficient length and
width, with a maximum 2% gradient, covered with packed snow.
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.

For a vertical load higher or equal to 75% of the load capacity of the tyre, a
constant deflection is applied, hence the test inflation pressure "Pt" shall be
calculated as follows:
P
⎛ Q
= P

⎝ Q



Q
P
Q
is the maximum load associated to the load capacity index of the tyre
written on the sidewall
is the reference pressure corresponding to the maximum load capacity Q
is the static test load of the tyre
For a vertical load lower than 75% of the load capacity of the tyre, a constant
inflation pressure is applied, hence the test inflation pressure P shall be
calculated as follows:
P = P (0.75)
= (0.7) P
P
is the reference pressure corresponding to the maximum load capacity Q
3.23.3.1.5. Instrumentation
Check the tyre pressure just prior to testing at ambient temperature.
The vehicle shall be fitted with calibrated sensors suitable for measurements in
winter. There shall be a data acquisition system to store measurements.
The accuracy of measurement sensors and systems shall be such that the
relative uncertainty of the measured or computed mean fully developed
decelerations is less than 1%.
3.23.3.2. Testing Sequences
3.23.3.2.1. For every candidate tyre and the standard reference tyre, ABS-braking test runs
shall be repeated a minimum of six times.
The zones where ABS-braking is fully applied shall not overlap.
When a new set of tyres is tested, the runs are performed after shifting aside the
vehicle trajectory in order not to brake on the tracks of the previous tyre.
When it is no longer possible not to overlap full ABS-braking zones, the test
course shall be re-groomed.

3.23.3.4.1.2. Weighted averages of two successive tests of the SRTT shall be computed
taking into account the number of candidate tyres in between:
In the case of the order of testing R1 - T - R2, the weighted average of the SRTT
to be used in the comparison of the performance of the candidate tyre shall be
taken to be:
Where:
wa(SRTT) = (R1 + R2)/2
R1
is the mean mfdd for the first test of the SRTT and R2 is the mean mfdd
for the second test of the SRTT.
In the case of the order of testing R1 – T1 – T2 – R2, the weighted average (wa)
of the SRTT to be used in the comparison of the performance of the candidate
tyre shall be taken to be:
wa (SRTT) = 2/3 R1 + 1/3 R2 for comparison with the candidate tyre T1; and:
wa (SRTT) = 1/3 R1 + 2/3 R2 for comparison with the candidate tyre T2.
3.23.3.4.1.3. The snow grip index (SG) of a candidate tyre shall be computed as:
3.23.3.4.2. Statistical validations
Snow Grip Index (candidate) =
Mean (candidate)
wa (SRTT)
The sets of repeats of measured or computed mfdd for each tyre should be
examined for normality, drift, eventual outliers.
The consistency of the means and standard-deviations of successive braking
tests of SRTT should be examined.
The means of two successive SRTT braking tests shall not differ by more
than 5%.
The coefficient of variation of any braking test shall be less than 6%.
If those conditions are not met, tests shall be performed again after re-grooming
the test course.
3.23.3.4.3. 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.

3.23.4.3.2. The following tolerances shall be respected:
(a) For speed measurements: ±1% (km/h) or 0.5km/h whichever is greater.
(b)
For distance measurements: ±1 × 10 m
3.23.4.3.3. A display of the measured speed or the difference between the measured speed
and the reference speed for the test is recommended inside the vehicle so that
the driver can adjust the speed of the vehicle.
3.23.4.3.4. For Acceleration test covered in Paragraph 3.23.4.7., a display of the slip ratio of
the driven tyres is recommended inside the vehicle and shall be used in the
particular case of Paragraph 3.23.5.7.2.1.1.
The slip ratio is calculated by
⎡ Wheel Spee d - Vehicle Speed ⎤
Slip Ratio % = ⎢
× 100
Vehicle Speed



(a)
(b)
Vehicle speed is measured as defined in 3.23.4.3.1 (m/s)
Wheel speed is calculated on a tyre of the driven axle by measuring its
angular velocity and its loaded diameter
Wheel Speed = π × loaded diameter × angular speed
Where:
π
= 3.1416 (m/360°), the loaded diameter (m) and the angular speed
(revolution per second = 360°/s).
3.23.4.3.5. A data acquisition system can be used for storing the measurements.
3.23.4.4. General Conditions
3.23.4.4.1. 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.
3.23.4.4.1.1. 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.
3.23.4.4.1.2. 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.
3.23.4.4.1.3. 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.

3.23.4.7. Acceleration on Snow Test Procedure for Snow Grip Index of Class C3N and
C3W
3.23.4.7.1. Principle
3.23.4.7.2. Vehicle
The test method covers a procedure for measuring the snow grip performance of
commercial vehicle tyres during acceleration, using a commercial vehicle having
a Traction Control System (TCS, ASR, etc.).
Starting with a defined initial speed, the full throttle is applied to activate the
traction control system, the average acceleration is calculated between two
defined speeds.
3.23.4.7.2.1. The test shall be conducted with a standard two axle commercial vehicle in good
running order with:
(a)
(b)
(c)
(d)
Low rear axle weight and an engine powerful enough to maintain the
average percentage of slip during the test as required in
Paragraphs 3.23.4.7.5.1. and 3.23.4.7.5.2.1. below;
A manual gearbox (automatic gearbox with manual shift allowed) having a
gear ratio covering the speed range of at least 19km/h between 4km/h and
30km/h;
Differential lock on driven axle is recommended to improve repeatability;
A standard commercial system controlling/limiting the slip of the driving
axle during acceleration (traction control, ASR, TCS, etc.)."
3.23.4.7.2.1.1. 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 3.23.4.3.4. of this Annex and
a mandatory differential lock on the driven axle used in accordance with
operating procedure 4.7.4.2.1. 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.
3.23.4.7.2.2. 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.
Any other modification of the acceleration system is prohibited.

3.23.4.7.5.2.1. In the particular case of Paragraph 3.23.4.7.2.1.1. of this Annex where a
standard commercial vehicle equipped with a traction control system is not
available, the driver shall manually maintain the average slip ratio between
10 and 40% (controlled slip procedure in place of the full slip) within the
prescribed range of speeds. If a differential lock is not available, the averaged
slip ratio difference between the left and right driven wheel shall not be higher
than 8% for each run.
All the tyres and runs in the test session are performed with controlled slip
procedure.
3.23.4.7.5.3. Measure the distance between the initial speed and the final speed.
3.23.4.7.5.4. For every candidate tyre and the standard reference tyre, the acceleration test
runs shall be repeated a minimum of six times and the coefficients of variation
(standard deviation/average*100) calculated for minimum six valid runs on the
distance shall be lower than or equal to 6%.
3.23.4.7.5.5. In case of traction control system equipped vehicle, the average slip ratio shall
be in the range from 10% to 40% (calculated as per Paragraph 3.23.4.3.4.).
3.23.4.7.5.6. Apply testing sequence as defined in Paragraph 3.23.4.6.
3.23.4.8. Processing of Measurement Results
3.23.4.8.1. Calculation of the Average Acceleration AA
Each time the measurement is repeated, the average acceleration AA (m·s ) is
calculated by:
AA =
S
- S
2D
Where D (m) is the distance covered between the initial speed S (m.s ) and the
final speed S (m.s ).
3.23.4.8.2. 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.
stdev
Coefficien t of var iation = × 100
average

3.23.4.8.4. "AFC" Calculation (Acceleration Force Coefficient)
Also called AFC Acceleration Force Coefficient
Calculation on of AFC(Ta) and AFC(Ra) as defined in Table 2:
Table 2
The Acceleration Force Coefficient "AFC" is:
Reference tyre AFC(R) =
Candidate tyre AFC(T) =
Ra
g
Ta
g
3.23.4.8.5. 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.
3.23.4.8.6. Calculation of the slip ratio
Snow Grip Index =
AFC(T)
AFC(R)
The slip ratio can be calculated as the average of slip ratio as mentioned in
Paragraph 3.23.4.3.4. of this Annex or by comparing the average distance
referred to in Paragraph 3.23.4.7.5.3. of this Annex of the minimum six runs to
the distance of a run done without slip (very low acceleration)
⎡ Average distance - No slip dis tance ⎤
Slip Ratio % - ⎢
× 100
No slip distance



No slip distance means the wheel distance calculated on a run done with a
constant speed or a continuous low acceleration.
3.23.4.9. Snow Grip Performance Comparison between a Candidate Tyre and a
Reference Tyre using a Control Tyre
3.23.4.9.1. 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.

ANNEX 1
SPEED SYMBOL TABLE
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
Nominal rim diameter code ("d" symbol)
Value of the "d" symbol expressed in mm
8
203
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
482
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
28
711
30
762

ANNEX 4
RELATION BETWEEN THE PRESSURE INDEX ('PSI') AND THE UNITS OF PRESSURE (KPA)
(CONTINUED)
kPa psi kPa psi kPa psi kPa psi
215 31 475 69 740 107 1,000 145
220 32 480 70 745 108 1,010 146
230 33 490 71 750 109 1,015 147
235 34 495 72 760 110 1,020 148
240 35 500 73 765 111 1,030 149
250 36 510 74 775 112 1,035 150
255 37 520 75 780 113 1,040 151
260 38 525 76 785 114 1,050 152

ANNEX 5
VARIATION OF LOAD CAPACITY WITH SPEED COMMERCIAL VEHICLES TYRES
(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
130

Table B
Tyres for Light Commercial Vehicles
Tyre size
designation
Measuring rim
width code
Nominal rim diameter
d (mm)
Outer diameter
D (mm)
Section width
S (mm)
Metric designated
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
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
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
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
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
17 R 15 C
17 R 380 C
17 R 400 C
19 R 400 C
5.00
5.00
150mm
150mm
381
381
400
400
678
678
698
728
178
178
186
200
Code designated
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
5.00
5.00
5.00
5.00
305
330
330
356
381
570
648
660
688
712
150
172
180
180
180

Table D
Tyres with LT Designation
Tolerances shown at the bottom of the tables apply in place of those shown in
Paragraphs 3.21.1.4.2.2.2. and 3.21.1.3.2.
Outer diameters are listed for the various categories of use: Normal, Snow, and Special.
Tyre size
designation
Measuring rim
width code
Nominal rim diameter
d (mm)
Outer diameter
D (mm) Section width
S (mm)
Normal Snow
6.00R16LT 4.50 406 732 743 173
6.50R16LT 4.50 406 755 767 182
6.70R16LT 5.00 406 722 733 191
7.00R13LT 5.00 330 647 658 187
7.00R14LT 5.00 356 670 681 187
7.00R15LT 5.50 381 752 763 202
7.00R16LT 5.50 406 778 788 202
7.10R15LT 5.00 381 738 749 199
7.50R15LT 6.00 381 782 794 220
7.50R16LT 6.00 406 808 819 220
8.25R16LT 6.50 406 859 869 241
9.00R16LT 6.50 406 890 903 257
G78R15LT 6.00 381 711 722 212
H78R15LT 6.00 381 727 739 222
L78R15LT 6.50 381 749 760 236
L78R16LT 6.50 406 775 786 236
7R14.5LT 6.00 368 677 185
8R14.5LT 6.00 368 707 203
9R14.5LT 7.00 368 711 241
7R17.5LT 5.25 445 758 769 189
8R17.5LT 5.25 445 788 799 199

Tyre-size
designation
Table E
High Flotation LT Tyres (Continued)
Measuring rim
width code
Nominal rim diameter
d (mm)
Outer diameter
D (mm) Section width
S (mm)
Normal Snow
33 × 12.50R22LT 10.00 559 826 832 318
33 × 13.50R15LT 11.00 381 826 832 345
33 × 15.50R15LT 12.00 381 826 832 390
34 × 10.50R17LT 8.50 432 851 858 268
34 × 12.50R18LT 10.00 457 851 858 318
35 × 12.50R15LT 10.00 381 877 883 318
35 × 12.50R17LT 10.00 432 877 883 318
35 × 12.50R18LT 10.00 457 877 883 318
35 × 12.50R20LT 10.00 508 877 883 318
35 × 12.50R22LT 10.00 559 877 883 318
35 × 13.50R15LT 11.00 381 877 883 345
35 × 13.50R18LT 11.00 457 877 883 345
35 × 13.50R20LT 11.00 508 877 883 345
35 × 14.50R15LT 12.00 381 877 883 372
36 × 13.50R18LT 11.00 457 902 908 345
36 × 14.50R15LT 12.00 381 902 908 372
36 × 14.50R17LT 12.00 432 902 908 372
36 × 14.50R18LT 12.00 457 902 908 372
36 × 15.50R15LT 12.00 381 902 908 390
37 × 12.50R15LT 10.00 381 928 934 318
37 × 12.50 R17LT 10.00 432 928 934 318
37 × 12.50R18LT 10.00 457 928 934 318
37 × 12.50R20LT 10.00 508 928 934 318

Tyre-size
designation
Table E
High Flotation LT Tyres (Continued)
Measuring rim
width code
Nominal rim diameter
d (mm)
Outer diameter
D (mm) Section width
S (mm)
Normal Snow
40 × 14.50R20LT 12.00 508 1004 1010 372
40 × 15.50R20LT 12.00 508 1004 1010 390
40 × 15.50R22LT 12.00 559 1004 1010 390
40 × 15.50R24LT 12.00 610 1004 1010 390
42 × 14.50R17LT 12.00 432 1055 1061 372
42 × 14.50R20LT 12.00 508 1055 1061 372
8.00R16.5LT
6.00
419
720
730
203
8.75R16.5LT
6.75
419
748
759
222
9.50R16.5LT
6.75
419
776
787
241
10R16.5LT
8.25
419
762
773
264
12R16.5LT
9.75
419
818
831
307
30 × 9.50R16.5LT
7.50
419
750
761
240
31 × 10.50R16.5LT
8.25
419
775
787
266
33 × 12.50R16.5LT
9.75
419
826
838
315
35 × 12.50 R16.5LT
10.00
419
877
883
318
37 × 12.50R16.5LT
9.75
419
928
939
315
37 × 14.50R16.5LT
11.25
419
928
939
365

ANNEX 8
ROLLING RESISTANCE TEST EQUIPMENT TOLERANCES
1. PURPOSE
The limits specified in this Annex are necessary in order to achieve suitable levels of
repeatable test results, which can also be correlated among various test laboratories. These
tolerances are not meant to represent a complete set of engineering specifications for test
equipment; rather, they should serve as guidelines for achieving reliable test results.
2. TEST RIMS
2.1. Width
2.2. Run-out
For passenger car tyre rims (C1 tyres), the test rim width shall be the same as the
measuring rim determined in ISO 4000-1: 2010 Clause 6.2.2.
For truck and bus tyres (C2 and C3), the rim width shall be the same as the measuring rim
determined in ISO 4209-1:2001, Clause 5.1.3.
In cases where the width is not defined in the above mentioned ISO Standards, the rim
width as defined by one of the standards organizations as specified in Annex 7 may be
used.
Run-out shall meet the following criteria:
(a)
(b)
Maximum radial run-out: 0.5mm;
Maximum lateral run-out: 0.5mm.
3. DRUM/TYRE ALIGNMENT
General:
Angle deviations are critical to the test results.
3.1. Load Application
The direction of tyre loading application shall be kept normal to the test surface and shall
pass through the wheel centre within
(a)
(b)
1mrad for the force and deceleration methods;
5mrad for the torque and power methods.

5. INSTRUMENTATION ACCURACY
The instrumentation used for readout and recording of test data shall be accurate within the
tolerances stated below:
Parameter Load Index ≤121 Load Index >121
Tyre load ±10N or ±0.5% ±30 N or ±0.5 %
Inflation pressure ±1kPa ±1.5kPa
Spindle force ±0.5N or ±0.5% ±1.0N or ±0.5%
Torque input ±0.5Nm or ±0.5% ±1.0Nm or ±0.5%
Distance ±1mm ±1mm
Electrical power ±10W ±20W
Temperature
Surface speed
±0.2°C
±0.1km/h
Time ±0.01s – ± 0.1% – ± 10s
Angular velocity ±0.1%
6. COMPENSATION FOR LOAD/SPINDLE FORCE INTERACTION AND LOAD
MISALIGNMENT FOR THE FORCE METHOD ONLY
Compensation of both load/spindle force interaction ("cross talk") and load misalignment
may be achieved either by recording the spindle force for both forward and reverse tyre
rotation or by dynamic machine calibration. If spindle force is recorded for forward and
reverse directions (at each test condition), compensation is achieved by subtracting the
"reverse" value from the "forward" value and dividing the result by two. If dynamic machine
calibration is intended, the compensation terms may be easily incorporated in the data
reduction.
In cases where reverse tyre rotation immediately follows the completion of the forward tyre
rotation, a warm-up time for reverse tyre rotation shall be at least 10 minutes for Class C1
tyres and 30min for all other tyre types.
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.

2. CLASS C2 AND C3 TYRES
The measuring rim width R is equal to the product of the nominal section width S , and the
coefficient K :
R = K x S rounded to the nearest standardized rim width.
Table 1
Coefficients for Determining Measuring Rim Width
Tyre Structure
Code
Type of rim Nominal aspect ratio H/S Measuring rim/section ratio K
B, D, R
5° tapered
100 to 75
0.70
70 and 65
0.75
60
0.75
55
0.80
50
0.80
45
0.85
40
0.90
15° tapered
(drop-centre)
90 to 65
0.75
60
0.80
55
0.80
50
0.80
45
0.85
40
0.85

2.2. Work out the system for four equations each of the form:
Z
= A ln
cosB (T - t
cosB T
)
where unknowns:
A
B
T
is a dimensionless constant,
is a constant in revolutions per second,
is a constant in seconds,
M is the number of bounds shown in Figure 1.
Insert in these four equations the coordinates of 4-th bound above.
2.3. Take constants A, B and T as the solution of the equation system of Paragraph 2.2. above
using iteration process and approximate measured data by formulae:
Z (t) = Aln
cosB (T - t)
cosB T
where:
z(t)
t
is the current continuous angular distance in number of revolutions (not only integer
values);
is time in seconds.
Note 2: Other approximating functions z = f(t ) may be used if their adequacy is proven.
3. Calculate the deceleration j in revolutions per second squared (s ) by the formula:
where:
J = AB
+
ω
A
ω is the angular speed in revolutions per second (s ).
For the case Un = 80km/h; ω = 22.222/Rr (or R).
For the case Un = 60km/h; ω = 16.666/Rr (or R).
4. Estimate the quality of approximation of measured data and its accuracy by parameters:
4.1. Standard deviation in percentages:
1
σ = ∑
n − 1
[1 −
( t)
z
z
]
× 100%

Tyres.