In the USA, a panel of three federal judges has rejected a proposed tyre pressure monitoring system (TPMS) as it allowed too great a margin for error. TPMS was made compulsory in new cars following the Ford Explorer/Firestone tyre episode. The National Highway Traffic Safety Administration was ordered to come up with a TPMS for cars and it offered two systems – one which required a sensor on all four tyres (direct system) and one which used existing technology systems, such as ABS, to estimate pressure (indirect system). Consumer groups claimed that the second system was not effective all the time, and thus did not meet the law’s requirements, and the judges agreed, ordering the NHTSA to formulate a new rule.

The argument of the consumer groups was that indirect TPMS works by comparing the speeds of two diagonal wheels with the other two diagonal wheels and, as such, cannot tell whether all four tyres are under-inflated or whether two tyres on the same axle or the same side of the vehicle are under-inflated. The judges accepted this view and one of them, Robert D. Sack, said “The record discloses that the added cost for a system that worked all the time, rather than half of the time, was less than $10 per car.”

A possible beneficiary of the ruling could be Goodyear Tire & Rubber, which has developed a direct monitoring system in partnership with Siemens VDO, whereby a computer chip embedded in the tyre warns the driver of air pressure loss via radio signals to a dashboard display. The system is currently being tested by several vehicle manufacturers for their 2006 models. A Goodyear spokesperson said “we think the debate will continue between the automotive industry and consumer groups for a while. Either way, we support tyre pressure monitoring systems.”

Consumer groups were less diplomatic, hailing the decision as “perfect”. Clarence Ditlow, executive director of the Center for Auto Safety – a frequent critic of the auto industry – made his position plain when he said “This decision will block the pro-industry, anti-consumer, deregulatory campaign of the Bush administration”. This is a reference to the fact that it was the White House’s Office of Management and Budget, which had wanted a TPMS that was less costly than direct monitoring.

For the vehicle makers, a spokesperson for the lobbying group the Alliance of Automobile Manufacturers said that the AAM prefers a system that would allow auto manufacturers to choose between technologies. The spokesperson added: “the cost gap between the direct and indirect systems appeared to be wider than that cited in the ruling”, which would appear to be an indication that we may not yet have heard the last word on the subject.