Current Issue
Published on November 30, 2001

Tire load-carrying rule needed



AKRON (Nov. 30, 2001)—Does it make sense to have a pressure monitoring system that allows tires to run 25 to 30 percent underinflated before issuing some type of warning, as some auto makers have recommended?

It doesn't to us, unless there is a minimum load-carrying capacity requirement for tires as well.

The whole point of requiring pressure monitoring systems on vehicles is to protect the safety of the driving public by keeping tires operating properly.

Running tires underinflated with no minimum load-carrying capacity requirement could result in unsafe operating conditions. And it would defeat the purpose of the TREAD Act's mandate that all new vehicles starting in November 2003 come equipped with tire pressure monitoring systems.

The National Highway Traffic Safety Administration is about to issue requirements for tire pressure monitoring systems and is weighing comments by auto and tire makers and others.

As might be expected, there's tremendous disagreement about what should be required.

Part of the controversy involves whether such systems should monitor tire pressure directly using a radio transmitter in each wheel or indirectly using existing vehicle systems such as anti-lock brakes. We, like most of the tire industry, prefer direct monitoring systems because of their ability to pinpoint underinflation to a specific tire.

However, regardless of the system chosen, motoring safety will remain questionable unless the vehicle's tires have sufficient load-carrying capacity—even when underinflated.

No monitoring system will prevent tire overloading unless the tires' reserve load-carrying capacity is sufficient to support the vehicle's weight when pressure declines enough to set off the alarm. In other words, whatever tire size the auto maker chooses for a particular vehicle must have enough reserve capacity to support that vehicle at the allowable minimum pressure.

The Rubber Manufacturers Association and other tire industry groups have urged NHTSA to include such a requirement in its final rule. NHTSA should comply.


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