TIRE PRESSURE LIGHT ON WHEN IT GETS COLD?
The first cold morning of the season, and a tire pressure light is on. It is one of the most common dashboard lights in fall and winter. Here is why cold weather sets it off, how to fix it, and when it means something else.
📞 Call About a Tire Pressure LightYou start the car on a chilly morning and a tire-shaped light is glowing on the dash. Nothing looks flat. That is often just the weather. Cold air takes up less space, so the air in your tires pushes with less force. Here is how that works and what to do about it.
Cold air lowers tire pressure by about 1 psi for every 10°F the temperature drops. When a tire falls about 25% below the recommended pressure, the light comes on. Check all four tires when they are cold and fill them to the pressure on your door placard. If the light flashes, or keeps coming back, something else is going on.
WHY THE LIGHT COMES ON IN COLD WEATHER
Two things add up. First, as a rule of thumb, tire pressure drops about 1 psi for every 10°F the temperature falls. Second, tires lose a little air slowly all the time, because air passes through the rubber, and sources put that at anywhere from a fraction of a psi to about 1 psi a month.
A GM tire engineer gave this example: if you last checked your pressure when it was 70°F and it is now 20°F, a tire that should be at 35 psi could be down to 27 or 28 and set off the warning. Tire pressure monitoring systems have been required on new vehicles since 2007, and the federal safety rule requires the alert when a tire is 25% below its recommended pressure.
WHAT TO DO WHEN THE LIGHT COMES ON
- Find your recommended pressure. It is on the placard on the driver's door edge or door jamb. Do not use the maximum number printed on the tire.
- Check when the tires are cold. That means the car has been parked for a few hours, or driven less than a mile. Driving warms the tires and raises the reading by a few psi.
- Check all four tires with a gauge. The light does not say which tire is low.
- Fill each tire to the placard pressure. Usually the light goes off once the pressure is right.
Do not ignore a tire that is far below pressure. A tire that is 25% low is well under-inflated. Check it soon, and avoid long highway drives until you have.
WHAT THE LIGHT IS TELLING YOU
| What you see | Likely meaning | What to do |
|---|---|---|
| Steady light after a cold snap | One or more tires low from the cold | Fill to door-placard pressure |
| Light comes back after adding air | A slow leak, such as a nail or valve stem | Have the tire checked |
| Light flashes, then stays on | A problem with the monitoring system | Have the system checked |
| Tire looks flat | A puncture or a large leak | Do not drive far on it |
A HABIT THAT PREVENTS IT
Check your tire pressure at least once a month with a quality gauge, and again when the first real cold weather arrives. Winter also covers more than tires, so see our winter car checklist. For flats, nails and sensor service, see our tire shop page.
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Sources: GM tire engineer quoted on cold weather and TPMS · Why your tire pressure warning light turns on during cold weather · Rick's Free Auto Repair Advice: TPMS light in cold weather. Figures such as 1 psi per 10°F are rules of thumb. General information, not a diagnosis of your car. Your door placard has the correct pressure for your vehicle.
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