The National Highway Traffic Safety Administration is evaluating a proposed new regulation that would require a tire pressure monitoring system (TPMS) on all passenger cars, light trucks (pickups, vans, and sport utility vehicles), and buses with a gross vehicle weight rating (GVWR) of 10,000 pounds or less (collectively this group is called "passenger vehicles" throughout this assessment). This is in accordance with the TREAD Act (H.R. 5164), Sec. 13. Tire Pressure Warning: "Not later than 1 year after the date of the enactment of this Act, the Secretary of Transportation shall complete a rulemaking for a regulation to require a warning system in new motor vehicles to indicate to the operator when a tire is significantly under-inflated. Such requirement shall become effective not later than 2 years after the date of the completion of such rulemaking." This means that the agency must issue a final rule by November 1, 2001 and the effective date would be before November 1, 2003.