The National Highway Traffic Safety Administration (NHTSA) released a survey Aug. 29 that found about a third of all light trucks and a quarter of cars have at least one substantially underinflated tire. Transportation Secretary Norman Y. Mineta urged drivers to check their tire pressure. "Driving with substantially underinflated tires can lead to crashes and tragedy, in addition to reducing fuel efficiency and shortening tire life," Mineta said. NHTSA said its check of 11,530 vehicles around the country shows that despite government and industry warnings that underinflated tires can lead to deadly highway accidents, many people still are not keeping their tires inflated to recommended levels. NHTSA recommends that tire pressure be checked once a month and before every long trip. Spokesman Rae Tyson recommends making the tire pressure check a regular part of maintenance, just like checking the oil.The survey, conducted during two weeks in February, considered a tire underinflated if it was eight pounds per square inch or more below the vehicle manufacturer's recommended inflation pressure. That represents 25 percent underinflation for a common recommended inflation pressure of 32 psi. The survey found 27 percent of cars and 32 percent of vans, pickups and sport utility vehicles had at least one tire that was underinflated. Six percent of light trucks and 3 percent of cars checked had all four tires underinflated. All vehicles made after November 2003 will be required to have a system to warn drivers about low tire pressure under a rule being hammered out by NHTSA. The agency estimates the system will prevent dozens of deaths and thousands of injuries each year. The Rubber Manufacturers Association, for its part, has begun a multimillion-dollar campaign to encourage proper tire care called "Be Tire Smart - Play your PART." PART stands for pressure, alignment, rotation and tread, the key aspects of tire maintenance. Only 4 percent of respondents to a survey conducted for the association last year mentioned tire pressure checks when asked what routine tire maintenance is done on their vehicles. More than half -- 55 percent -- did not know where to find the correct pressure recommendation for their tires, which is in the owner's manual and on the vehicle doorjamb.