Why Tires Go Flat in Cold Weather

Reasons warning lights shine when the temperatures fall

wintery road with caution sign and person checking their car tire in background Photo: Getty Images

As winter approaches, many motorists will experience a low-pressure warning light on the dash or simply observe that the tires look a bit less full than they should. The main reason for this is the dropping temperatures, which cause the air to become denser and consequently lower the tire pressure. Couple that with tires naturally losing pressure over time, and fall and winter can be a busy time for pressure checks and adding a little air.

Tire pressure monitoring systems (TPMS) are a real boon to safety and convenience, and they have been required on all new cars since September 2007. The TPMS uses a dashboard light to let you know when one or more tires is significantly low on air. As a general rule, check the pressure monthly. Don’t wait for the tire pressure warning light to come on. It’s meant to alert you of a tire losing air while you’re driving, not serve as a maintenance reminder.

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Getting a tire pressure warning light on a chilly morning doesn’t necessarily indicate a puncture, just that your tires are running low pressure and that you need to top them off as soon as possible. Colder temperatures will cause tire pressure to drop about 1 pound per square inch for every 10° F drop in air temperature. 

If you don’t fill up at home, the warning light may turn off after driving a few miles because of heat building up in the tires. Whether it goes off or not, your tire pressure needs to be checked with a gauge and topped off. This is a simple DIY chore, or you can ask a mechanic to have a look. (See our tire pressure gauge buying guide.)

Even if your vehicle is equipped with a TPMS, our recommendation is to use a gauge to check the pressure in all your tires, including the spare, at least once per month, no matter what the weather is like. And be prepared as the weather cools to tend to this important chore. 

Jeff S. Bartlett

A New England native, I have piloted a wide variety of vehicles, from a Segway to an aircraft carrier. All told, I have driven thousands of vehicles—many on race tracks across the globe. Today, that experience and passion are harnessed at the CR Auto Test Center to empower consumers. And if some tires must be sacrificed in the pursuit of truth, so be it. Follow me on Twitter (@JeffSBartlett).