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Many U.S. Vehicles are Driven on Under-Inflated Tires

Fleet managers (and other drivers) take note: If you're disappointed that you have to fill up on gas so often, the U.S. Department of Transportation (DOT) has this advice for you: check your tire inflation. Read More

(Updated on July 24, 2024)

Fleet managers (and other drivers) take note: If you’re disappointed that you have to fill up on gas so often, the U.S. Department of Transportation (DOT) has this advice for you: check your tire inflation.

According to a survey performed by DOT’s National Highway Traffic Safety Administration (NHTSA), fully 27 percent of U.S. passenger cars are riding on at least one under-inflated tire, as are 32 percent of light trucks (including sport utility vehicles, vans and pickup trucks).

For purposes of the survey, a tire was considered under-inflated at 8 pounds per square inch (psi) or more below the vehicle manufacturer’s recommended inflation pressure. That’s significant, as every 2 psi of under-inflation per tire leads to a one percent increase in fuel consumption caused by increased rolling resistance.

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 Web site at: www.nhtsa.dot.gov/people/ncsa.

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