The U.S. Department of Transportation's National Highway Traffic Safety Administration (NHTSA) today proposed a new federal motor vehicle safety standard requiring the installation of tire pressure monitoring systems in new passenger cars, light trucks, buses and multipurpose passenger vehicles with gross vehicle weight ratings of 10,000 pounds or less to warn the driver when the vehicle has a significantly underinflated tire.
The agency is seeking comment on two alternative versions of the regulation. Only one version will be in the final rule.
One alternative would require that the driver be warned when the pressure in one or more tires, up to a total of four tires, has fallen to 20 percent or more below the vehicle manufacturer's recommended cold inflation pressure for the vehicle's tires, or a minimum level of pressure to be specified in the new standard, whichever is higher.
The other alternative would require that the driver be warned when tire pressure in one or more tires, up to a total of three tires, has fallen to 25 percent or more below the vehicle manufacturer's recommended cold inflation pressure for the vehicle's tires, or a minimum level of pressure to be specified in the new standard, whichever is higher.
NHTSA estimates that 49 to 79 deaths and 6,585 to 10,635 injuries could be prevented each year if all vehicles were equipped with tire pressure monitoring systems. Consumers would benefit from increased fuel economy and longer tire wear. In addition, there would be benefits resulting from fewer crashes due to tire blowouts, immobilized vehicles, or poor vehicle handling from pressure loss and hydroplaning.
For the next 45 days, the public may submit comments in writing to: Docket Section, National Highway Traffic Safety Administration, 400 Seventh Street, S.W., Washington, D.C. 20590. Alternatively, comments can be submitted electronically by logging onto the Docket Management System (DMS) website at dms.dot.gov
. Click on "Help & Information" or "Help/Info" to view instructions. Cite docket number 2000-8572 in either written or electronic submissions. The full text of the proposal and associated documents are on display at the Web site.
The National Highway Traffic Safety Administration (NHTSA) rule is the first new standard that directly affects consumers and the design of their vehicles under a law passed last year in reaction to the Firestone tire recall. A similar system in was proposed by NHTSA in 1981 but was abaondoned because of the expense and technical problems.
Some carmakers already offer such warning systems in their vehicles, as standard or optional equipment, and say they work well. But the equipment isn't mandatory.
The legislation responds to the underinflation problem investigators found in checking the hundreds of injuries and 203 deaths linked to Firestone tire failures, most of them on Ford Explorer sport utility vehicles. In many of the cases the underinflated tires were carrying excessive loads.
The agency suggested that an indicator illuminate with a yellow light on the dashboard display within 10 minutes after a tire reaches the underinflation limit set in the rule.
The agency estimates that the cost of the two systems it is considering ranges from $66.33 per vehicle to $30.54 -- not counting savings from fuel economy and longer tire life.
A survey done for NHTSA last September found that almost three quarters -- 71 percent -- of drivers check their pressure less than once a month. Car owners often overlook slow leaks, climatic changes and damage to the tires from typical use.
Direct sensor systems are more accurate, broadcasting the pressure of each tire from a wireless transmitter in each wheel to a receiver in the car. The indirect systems can estimate pressure to within about 1.1 pound per square inch, but they do not tell the driver which tire is losing air.
General Motors already uses both systems on about 2 million of its vehicles.
Automakers told NHTSA during discussions as the proposal was being drafted to let the manufacturers decide what constitutes "significant underinflation." They cited the many different vehicles and tires involved.
Tiremakers wanted the agency to interpret "underinflated" very narrowly. The warning would be activated when the inflation of the tire no longer supports the weight it was designed for -- which could be as little as a pound or two.