The U.S. Department of Transportation's National Highway Traffic Safety Administration (NHTSA) is proposing a new safety standard to warn the driver when a tire is significantly under-inflated. Tire manufacturers say the system would not provide a timely warning.
The proposal requires manufacturers to install a four-tire Tire Pressure Monitoring System that is capable of detecting when a tire is more than 25 percent under-inflated and warning the driver.
The new standard also proposes to require a tire-pressure malfunction indicator, which would warn the driver when the system is not working properly. For example, tires might be installed on the vehicle that are incompatible with the pressure monitor, or other problems might cause the monitor to become inoperative.
The tire pressure monitor would be is a safety warning system and not a substitute for regular tire pressure maintenance by drivers, the agency said. Operating a vehicle with substantially under-inflated tires can result in a tire failure, such as instances of tread separation and blowouts, with the potential for a loss of control. Under-inflated tires also shorten tire life and increase fuel consumption.
The new Federal Motor Vehicle Safety Standard would apply to passenger cars, trucks, multipurpose passenger vehicles, and buses with a gross vehicle weight rating of 10,000 pounds or less, except those vehicles with dual wheels on an axle.
This department proposes the following three-year phase-in schedule:
• In the first model year, beginning Sept. 1, 2005, 50 percent of all light vehicles manufactured would comply.
• In the second model year, beginning Sept. 1, 2006, 90 percent of all light vehicles manufactured would comply.
• After Sept. 1, 2007, all light vehicles manufactured would comply.
But the Rubber Manufacturers Association, a trade group that represents tire makers, says the proposed rule is flawed and warned that the pressure monitor might increase the risk of tire failures by not providing a timely warning.
"Safety should be the overriding priority for this regulation," said Donald B. Shea, president and CEO of RMA. "A tire pressure monitor that doesn't provide a timely low-pressure warning to motorists is not enhancing safety."
RMA says that a 25 percent drop in a tire's recommended pressure may be insufficient to safely carry a fully loaded vehicle. Under NHTSA's proposed standard, motorists could be driving for thousands of miles on tires that are appreciably underinflated but still not receive a warning.
Driving on underinflated tires causes excessive heat buildup in tires that, over time, can result in hidden damage that can cause tire failure.
