TPMS technical spec battle set for today

ERJ staff report (DS)

Geneva, Switzerland -- Today will be a key day in the future of Europe's tyre pressure monitoring system legislation. An obscure technical meeting will decide what technical performance limits to place on the TPMS systems due to be installed on all new cars from 2012. The outcome of those discussions will affect safety and cost for all consumers in the region -- and probably in much of the rest of the world as well.

Responsibility for working out the details of the EU law has been passed to the United Nations Economic Commission for Europe (UNECE). But discussion in the UNECE's Working Party on Brakes and Running Gear (GRRF) has been dominated by car industry efforts to ensure the cheapest possible system be fitted.

The technical specifications will either permit or preclude the use of systems which offer slow response times, inaccurate measurements and critically, the availability to drivers of a reset buttton which can be use to pre-set the TPMS into an intrinsically unsafe condition.

Two broad technologies on the market claim to measure tyre pressure. Direct systems use a pressure sensor in each tyre -- including the spare. Indirect systems use ABS sensors to measure the rolling diameter of the four operational wheels and use software to interpret a reduction in diameter as a reduction in pressure.

These indirect systems will increase costs to consumers by over euro 1000 over the life of each vehicle, as car makers insist that original equipment tyres are used at each replacement. They are also slow to respond, but worst of all, they allow drivers to re-calibrate the system into an intrinsically unsafe mode.

Direct systems, by contrast, offer fast response times, accurate pressure measurement and lower cost to the consumer.

The FIA has issued a press release saying car makers must be free to fit the less safe indirect systems to cars, and giving false information about the costs to the car makers and ignoring the extra costs to the consumer.

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Press release from Transport and Environment

Press release from FIA