SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/cars-underinflated-tires-mpg

For every 1 psi your tires drop below normal, about how much gas mileage do you lose?

About 0.2% per psi, averaged across all four tires. It adds up fast.

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  1. Nothing until the warning light comes on
  2. About 0.2% per psi ✔
  3. About 5% per psi

Why: Soft tires roll with more drag. The Department of Energy says mileage drops about 0.2% for every 1 psi drop in average pressure. Ten psi low is about 2% wasted.

Huh, didn't know that: Keeping tires at the right pressure saves about 0.6% on average, and up to 3% in some cases.

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References

Answer: About 0.2% per psi. Soft tires roll with more drag. The Department of Energy says mileage drops about 0.2% for every 1 psi drop in average pressure. Ten psi low is about 2% wasted.

  1. Keeping Your Vehicle in Shape (fueleconomy.gov, US DOE) www.fueleconomy.gov/feg/maintain.jsp
    Under-inflated tires can lower gas mileage by about 0.2% for every 1 psi drop in the average pressure of all tires.
    Checked 2026-10-11.

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