Running the right tire pressure helps your tires wear evenly and lowers the risk of a tire failure, and checking it takes only a few minutes. The tricky parts are knowing which number to use and when to measure. Here are the basics.
Use the placard, not the sidewall
The vehicle manufacturer, not the tire maker, sets the right pressure for your tires. You'll find it on the Tire and Loading Information placard, usually on the driver's door jamb (the B-pillar), and in the owner's manual. If your vehicle has no B-pillar, check the rear edge of the driver's door. The placard may list different pressures for the front and rear tires, plus a separate figure for the spare.
The number molded into the tire sidewall is something else: it's the upper limit for that tire in normal driving, not a recommendation for your vehicle. Filling to it is a common mistake. Use the placard figure instead.
Check when the tires are cold
Driving warms the tires and pushes the reading up for a while. NHTSA counts a tire as cold once the vehicle has been parked for at least three hours, no matter the outside temperature. A check in the morning, before you head out, is an easy habit.
If you need to add air while the tires are warm, NHTSA suggests filling to the placard pressure and checking again once they cool. They may then read slightly low, which is still safer than driving on a badly underinflated tire.
How often to check
NHTSA recommends checking every tire, including the spare, at least once a month and before a long trip. Keep a gauge in the vehicle, since hitting a pothole or curb can cause a sudden loss of pressure. Tires also lose a little air naturally over time, one more reason for regular checks.
How temperature changes pressure
Tire pressure moves with the thermometer. AAA, Michelin and Bridgestone all put the change at about 1 psi for every 10°F. A tire set correctly on a mild fall afternoon can read several psi low on a frosty winter morning, and pressure climbs again as temperatures rise. Recheck after any big temperature swing.
What the TPMS light means
A federal safety standard requires a tire pressure monitoring system (TPMS) on new cars, SUVs, pickups and vans with a gross vehicle weight rating of 10,000 lb or less built since September 1, 2007, with limited exceptions. The low-pressure light must come on when one or more tires drops to 25 percent below the recommended cold pressure, or to a minimum level set by the standard if that is higher.
That makes the light a late warning, not a target. On a tire meant to run at 36 psi, it may not come on until the tire is down to about 27 psi.
- Light stays on: at least one tire is significantly low. Check all four with a gauge as soon as you safely can and inflate to the placard pressure.
- Light comes on during cold mornings, then goes off: pressure is marginally low. Check and top up.
- Light flashes for 60 to 90 seconds at startup, then stays on: the system itself has a fault. Have a dealer or tire shop inspect it.
The light should go off once the tires are properly inflated. If it doesn't, check your owner's manual for a reset procedure or have the system checked. Either way, TPMS backs up your monthly checks rather than replacing them.
Monthly tire pressure checklist
- Check before driving, while the tires are cold.
- Measure every tire with a reliable gauge, plus the spare if you have one.
- Compare each reading with the placard, front and rear.
- Add air or let some out as needed, then measure again.
- Look over the tread while you're down there.
- Recheck after a big temperature change.
For topping up at home, see the tire inflators in our Jump Starters & Tire Inflators collection.
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