Many U.S. Passenger Vehicles Are Driven on Under-inflated Tires, NHTSA Research Survey Shows

Many U.S. Passenger Vehicles Are Driven on Under-inflated Tires, NHTSA Research Survey Shows

Many U.S. Passenger Vehicles Are Driven on Under-inflated Tires, NHTSA Research Survey Shows

NHTSA
August 29, 2001

NHTSA 46-01
Wednesday, August 29, 2001
Contact: Elly Martin
Telephone: (202) 366-9550

NHTSA Research Survey Shows To Check Tire Pressure Before Labor Day Travel

Prompted by the Administration's emphasis on transportation safety and a new survey showing that many tires on passenger vehicles are under-inflated, U.S. Transportation Secretary Norman Y. Mineta today urged motorists to check their tire pressure and inflate them properly before setting out on trips for the Labor Day weekend.

"It is vitally important to safety to carefully monitor tire pressure on a regular basis, and I urge motorists to check their tires before setting out on Labor Day trips," Secretary Mineta said. "Driving with substantially under-inflated tires can lead to crashes and tragedy, in addition to reducing fuel efficiency and shortening tire life."

Safety is the Bush administration's highest priority for transportation.

Fully 27 percent of passenger cars on U.S. roadways are driven with one or more substantially under-inflated tires, according to a major survey conducted by the U.S. Department of Transportation's National Highway Traffic Safety Administration (NHTSA).

Moreover, 32 percent of light trucks (including sport utility vehicles, vans and pickup trucks) are driven with one or more substantially under-inflated tires, according to the first study of its kind to be conducted by the government in two decades.

A radial tire can lose much of its air pressure and still appear to be fully inflated. To help vehicle owners better monitor the air pressure in their tires, NHTSA last month proposed a new federal motor vehicle safety standard that would require the installation of tire pressure monitoring systems in new passenger cars and light trucks. The proposed requirement would also cover buses and multipurpose vehicles with a gross vehicle weight rating of 10,000 pounds or less. The new systems would warn the driver when a vehicle has a significantly under-inflated tire.

For purposes of the survey, a tire was considered under-inflated at 8 psi (pounds per square inch) or more below the vehicle manufacturer's recommended inflation pressure. This is 25 percent of a common recommended cold inflation pressure of 32 psi.

Operating a vehicle with substantially under-inflated tires can result in a premature tire failure, such as instances of tread separation and blowouts, with the potential for a loss of control of the vehicle. Under-inflated tires also shorten tire life and increase fuel consumption.

Tires should be inflated in accord with the vehicle manufacturer's recommendations. These can be found in the owner's manual or on a placard usually located on the driver's door jamb. Motorists should not rely on visual tire inspections to determine whether a tire is properly inflated but should use a tire pressure gauge to do so. Tire pressure should be checked at least once a month and before a long trip.

The study was based on information gathered by 67 data collectors who measured the inflation pressure of tires on 11,530 passenger vehicles during a 14-day period in February 2001. The information was collected with the cooperation of motorists who visited service stations for refueling at 300 sites in urban, suburban and rural settings located throughout the country.

Key findings of the NHTSA study include these estimates:

Six percent of light trucks (sport utility vehicles, vans and pickup trucks) are driven with all four of their tires under-inflated by 8 or more psi, compared with 3 percent of passenger cars.

Ten percent of light trucks are driven with three or more tires under-inflated by 8 or more psi, compared with 6 percent of passenger cars.

Twenty percent of light trucks have two or more tires under-inflated by 8 or more psi, compared with 13 percent of passenger cars.

The survey results also indicate that older vehicles are notably more likely to be operated with substantially under-inflated tires than are newer vehicles.

NHTSA estimates that 49 to 79 deaths and 6,585 to 10,635 injuries could be prevented annually if all vehicles were equipped with tire pressure monitoring systems. In addition, vehicle owners would benefit from better vehicle handling, increased tire life and better fuel economy.

NHTSA's National Center for Statistics and Analysis, which conducted the survey, plans to complete a detailed report on its tire pressure study by the end of 2001.

The newly released NHTSA statistics are contained in a research note on the agency's Website at: www.nhtsa.dot.gov/people/ncsa.

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