Why is my tire pressure low when it gets cold?

Cold air is denser than warm air. As the temperature drops, the air molecules inside your tire contract and take up less physical space, causing the pressure to drop even though no air actually leaked out of the tire.

How much PSI is lost per 10 degrees?

As a general rule of physics, a standard automotive tire will lose 1 PSI of pressure for every 10 degrees Fahrenheit drop in the outside ambient temperature.

Should I put more air in my tires in the winter?

Yes. If you last filled your tires during the warm summer months, you will need to add air in the late fall or winter to bring the pressure back up to the manufacturer's recommended level to compensate for the cold contraction.

Will my TPMS light turn off as the tire warms up?

Often, yes. If the pressure just barely dipped below the sensor's threshold overnight, driving the car will generate friction, heat up the tires, expand the air inside, and usually cause the TPMS light to turn off on its own.

Is it safe to drive with the tire pressure light on in winter?

It depends on the actual pressure. You should manually check the tire with a gauge. If it is only 2–3 PSI low due to the cold, it is safe to drive to a gas station. If it is significantly low, driving on it can overheat and destroy the tire sidewall.

Cold Weather Tire Pressure Drop Calculator

Calculate exactly how much PSI your tires will lose when the temperature drops, using the ideal gas law.

Quick Answer

If you fill your tires to 35 PSI in a warm 70°F garage, and the outside temperature drops overnight to 30°F, your tires will lose roughly 4 PSI due to cold air contraction. The next morning, your tires will read 31 PSI — often low enough to trigger the TPMS dashboard warning light.

Temperature unit:

Current pressurePSI

Warm temp°F

Cold temp°F

Scenarios:

Estimated PSI Loss by Temperature Drop

Starting Temp	New Ambient Temp	Temp Drop	Expected PSI Loss
70°F	60°F	−10°F	−1.0 PSI
70°F	50°F	−20°F	−2.0 PSI
70°F	40°F	−30°F	−3.0 PSI
70°F	30°F	−40°F	−4.0 PSI
70°F	20°F	−50°F	−5.0 PSI
70°F	0°F	−70°F	−7.0 PSI

Formula (Gay-Lussac's Law Rule of Thumb)

Expected PSI Loss = (Starting Temp°F − New Temp°F) ÷ 10

Rule of thumb = tires lose approximately 1 PSI per 10°F drop in ambient temperature
Gay-Lussac's Law = at constant volume, pressure is directly proportional to absolute temperature
Starting Temp = temperature when you last filled your tires
Example: (70°F − 30°F) = 40°F drop. 40 ÷ 10 = 4.0 PSI lost

Frequently Asked Questions

Related Tire Size Calculators

Tire Size Comparison Calculator Tire Size Converter Tire Diameter Calculator Gear Ratio & RPM Calculator

Back to All Tire Size Calculators All Calculators