Study: Underinflated tires a widespread hazard

A survey found 55 percent of drivers questioned did not know where to find their vehicle's recommended tire pressure.

By Julie Vallese
CNN Washington Bureau

WASHINGTON (CNN) -- A study released by the National Highway Traffic Safety Administration (NHTSA) on Wednesday indicated that more than one-fourth of passenger car tires and almost one-third of light truck tires may be underinflated.

Low tire pressure can cause several driver safety hazards as well as environmental problems. Tires with too little air can experience failure, tread separation and blowouts. Underinflation also shortens tire life span and decreases a vehicle's gas mileage, NHTSA said.

"It is vitally important to safety on our roadways that motorists carefully monitor tire pressure on a regular basis," said Secretary of Transportation Norman Mineta.

NHTSA estimated that 49 to 79 deaths and thousands of injuries could be prevented each year if vehicles were equipped with tire pressure warning devices.

The agency recommended that consumers familiarize themselves with proper tire inflation pressure listed in their vehicle owner's manual. Tire pressure should be checked monthly and before long trips, and not just by sight but with a tire pressure gauge, NHTSA said.

VIDEO CNN's Alexa Lee reports on the dangers of under-inflated tires (August 29) Play video (QuickTime, Real or Windows Media)

The survey was conducted as part of the so-called federal TREAD Act and was designed to determine how aware car and truck owners were of recommended tire pressures for their vehicles; how often they should check tire pressure; and how their measurements differed from recommended levels.

NHTSA said the information will be used to support various parts of the rulemaking process of the TREAD Act, including the government's decision to require car and truck manufacturers to equip their vehicles with tire pressure warning systems beginning in November 2003.

Truck tires more likely underinflated

The research indicated that light trucks -- including sport utility vehicles, vans and pickup trucks -- are more likely than passenger cars to have underinflated tires.

Overall, 32 percent of light trucks in the study had one or more underinflated tires, compared to 27 percent of passenger cars.

Of those, 10 percent of the light trucks had at least three underinflated tires, as did 6 percent of the passenger cars. Six percent of the light trucks and 3 percent of the cars had underinflation in all four tires.

In general, the study suggested that rear tires were more often underinflated than front tires and older cars were more likely to have lower tire pressure than new cars.

In the study, NHTSA measured tire pressure of 11,530 vehicles during a two-week period in February 2001. The measurements were taken at 300 service stations nationwide when motorists pulled in for refueling. A tire was considered underinflated when the level was at least 8 psi (pounds per square inch) less than the manufacturer's recommended air pressure.

NHTSA is a federal agency of the U.S. Department of Transportation and, according to its Web site, was created to set and enforce safety and performance standards for motor vehicles to reduce deaths, injuries and property damage.