Short answer
Yes. Heat causes the air inside a tire to expand, so tire pressure goes up as temperatures rise. A commonly cited rule of thumb is that pressure changes about 1 psi for every 10 degrees F change in temperature. That is an approximation, not an exact figure.
Why heat raises pressure
Air expands when warmed. Both hot weather and driving contribute: sunshine and warm pavement heat the tires, and the friction and flexing of driving warms them further. A tire that reads correctly when cold can read noticeably higher after a drive.
Cold vs. hot readings
The recommended pressure on your door jamb placard is a cold pressure. For an accurate reading, check the tires before driving or after the car has been parked for a few hours. See the tire pressure guide for where to find the number.
Should you lower your tire pressure in summer?
Generally, no. The placard pressure already allows for the normal rise from driving. Letting air out of warm tires can leave them underinflated once they cool. Sticking with the recommended cold pressure is the usual advice.
Should you put air in tires when it’s hot?
It is best to inflate when tires are cold. If you must add air when they are warm, expect the reading to be a bit high. Adding air toward the placard number is typically fine as a short-term fix, and you should recheck once the tires have cooled. For the steps, see how to inflate your tires.
Why does a tire lose pressure with no leak?
Temperature is a common reason. When temperatures fall, pressure falls too, so a tire can seem low on a cold morning even though nothing is leaking. Tires also lose a small amount of air naturally over time. If a tire keeps dropping after you have topped it up, it may have a slow leak, such as from a nail, valve or wheel, and should be inspected.
Risks of over- and underinflation in heat
Overinflated tires have less contact with the road, which can reduce traction and wear the center of the tread faster. Underinflated tires flex more and build up heat, which is a concern in hot conditions. Both are good reasons to check pressure regularly. Our article on low tire pressure symptoms covers the warning signs.
A simple summer routine
- Check pressure at least monthly, and before long trips
- Check in the morning when tires are cold
- Do not release air from hot tires to go below the placard number
- If the TPMS light comes on, check all four tires with a gauge (if they are fine, see tire pressure light on but tires are fine)