ECE Requirements on Tyre Pressure Monitoring Systems Published

After many months of discussion and negotiation, the new United Nations Economic Commission for Europe (UN ECE) requirements on tyre pressure monitoring systems were finally published on 10th November 2010. These new requirements have been published as an 02 series of amendments to ECE Regulation No. 64, which now covers temporary use spare wheels and tyres, run flat tyres and tyre pressure monitoring systems.

The need for agreed ECE requirements on tyre pressure monitoring systems was generated by the European Union when they published Regulation (EC) No. 661/2009 on general safety which mandated the fitment of tyre pressure monitoring systems for M1 category vehicles from 1st November 2012 for new types of vehicle. The European Union justified this mandatory requirement for tyre pressure monitoring systems on the grounds of both safety and environmental protection, as the loss of pressure in one or more tyres affects both the vehicle's handling characteristics and its fuel consumption/CO2 emissions.

Initial drafting of the ECE requirements was based on the pre-existing US legal requirements on tyre pressure monitoring systems contained in FMVSS 138. However, within the relevant group of experts, there was much discussion and negotiation over the thresholds at which the tyre pressure monitoring system should activate. Some of the experts proposed that the tyre pressure monitoring system should activate when the tyre pressure drops to 20% below its recommended inflation pressure, whereas other experts, notably those representing the vehicle manufacturers, thought that 20% was too severe and recommended a value of 25%. The vehicle manufacturers were concerned that, due to natural variations in the tyre inflation pressure that occur due to ambient temperature and the inherent tolerances in the pressure sensing equipment, a threshold of 20% could lead to the system being too sensitive and providing "false warnings". These "false warnings" could prove to be an annoyance to the driver and may even result in the driver ignoring the warnings.

The finally agreed requirements, which apply to the tyre pressure monitoring systems of both M1 and N1 category vehicles, specify that the system must give a warning when the tyre pressure in one or more tyres drops to 20% below its recommended inflation pressure, but allow an additional 5% tolerance to be applied to the tyre pressure measurements observed during the type approval tests.

The new requirements introduced into ECE 64.02 also include detailed technical requirements on the tyre pressure monitoring system (e.g. warning indication, malfunction detection, etc.) and test procedures for determining compliance with the technical requirements.

Although ECE 64.02 does not mandate the fitment of tyre pressure monitoring systems itself, it allows Contracting Parties to mandate compliance with these new requirements from 1st November 2012 for new types of vehicle and from 1st November 2014 for all new vehicles.