Low tire pressure light comes on in cold weather

Learn why the low tire pressure light comes on in cold weather

When the weather turns cold you often see the low tire pressure light come on. The TPMS sensor is designed to turn on the warning light when tire pressure falls to 25% or more of the recommended pressure. If you last filled your tires in warm weather, it’s not uncommon to see the warning light come on after a rapid drop in outside temperature. Here’s why.

Tire pressure drops 1-psi. for every 10°F drop in outside temperature

If you filled a few months ago when the temperature was 70°F and now the temperature is 0° F, your tire pressure dropped 7-psi. due to the temperature drop. That’s enough of a drop to turn on the low tire pressure light.

Be proactive and reset tire pressure as the cold arrives

As cold weather rolls in, check your tire pressure when the tires are cold and adjust the pressure to the match the label in the driver’s door area.

Remember that all tires lose pressure due to permeation

All tires lose 1-2-psi per month due to permeation; air that escapes through the tire. .

Refill tires to the recommended psi when they’re cold

The recommended tire pressure listed on the placard located in the driver’s door area if for cold tires; tires that haven’t been driven in at least 4 hours. If you see a TPMS light on first thing in the morning when your car is parked outside in the cold, simply fill the tires to the pressure listed on the placard.

If your vehicle is parked inside a heated garage, refer to the chart below and use the following calculation to determine the proper inflation pressure.
1) Measure the temperature inside the heated garage (Let’s assume 70°F)
2) Determine the lowest expected outside temperature in your area. (Let’s assume 14°F)
3) Subtract the lowest expected temperature from the heated garage temperature (70°F – 14°F = 56F)
4) Refer to the chart to determine the proper inflation pressure to add to the tire’s recommended pressure (from the placard). In this case approximately 4.8psi.

If you’ve driven the car to the tire shop, refer to the green dotted line.

If you’ve driven the car on the highway for at least one hour, refer to the blue dashed line.

©, 2022 Rick Muscoplat