From Tire Review Staff & Wire Reports
WASHINGTON — In response to recently proposed rulemaking by the National Highway Traffic Safety Administration (NHTSA) regarding tire pressure monitoring systems (TPMS) on passenger vehicles and light trucks, The Tire Industry Association (TIA) issued a release noting “serious concerns” about the proposal’s effect on safety.
Under the proposed rulemaking, new vehicles must be equipped with a system capable of detecting any tire that is inflated 25 percent below the vehicle manufacturer’s recommended inflation pressure.
“The recently proposed federal regulation does not fulfill the requirement of improving safety for motorists,” said TIA in its statement. “We have serious concerns about the threshold where the system would notify the driver of an underinflated tire,” said Roy Littlefield, executive vice president of TIA.
“For example,” he continued, “a car with a gross axle weight rating (GAWR) of 1,885 lbs on the front axle has a recommended cold inflation pressure of 32 psi, which can support 1,058 lbs per tire. If the 25 percent threshold is used, the resulting air pressure is 24 psi, so the carrying capacity of the tire will be less than 900 lbs per tire, thereby creating a potentially overloaded assembly. If a 20 percent threshold is used, the resulting air pressure is 26 psi, so the tire can support a load of 959 lbs. In this instance, a system that enacts at 20 percent would notify the driver that a potentially unsafe condition is about to occur. However, as soon as the inflation pressure drops below 26 psi, the tire can no longer support the GAWR, or the maximum weight on the front axle. If the new proposed threshold of 25 percent is adopted, the driver could be driving on an overloaded tire for a significant period of time.”
TIA additionally asserts that drivers of vehicles equipped with TPMSs will naturally have an improved sense of security as long as the sensors do not indicate an underinflated tire. “The question is whether or not it should enact before or after the unsafe condition occurs,” said TIA. “The concept of reserve load must also be resolved, and the current proposal does not adequately address the issue,” the organization noted.
“Given the serious concerns over the threshold where the system notifies the driver and the lack of current information on the importance of reserve load, we feel that the current proposal does not take all of the factors into consideration and will still result in vehicles being operated with tires that cannot support the load,” Littlefield concluded.
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