If your car has a tire pressure monitoring system (TPMS), you’ve probably seen the “low tire pressure” warning light, which usually looks like a horseshoe with an exclamation point. This warning often pops up more frequently when it gets cold outside. You might be wondering why this happens and if you need to add air to your tires.
When the temperature drops by about 10 degrees Fahrenheit, the air inside your tires contracts, which lowers the tire pressure by 1-2 pounds per square inch (PSI). PSI is just a way to measure pressure, like how much air is in your tires. Cold makes things smaller, while warmth makes them expand. During winter, it’s common for drivers to get these warnings because the cold weather makes the air in their tires shrink, causing them to be less inflated.
Even though it’s a usual thing to happen, it’s important not to ignore it. You might see the warning light in the morning when it’s coldest outside. Even if the temperature warms up later, the light might go off, but your tires could still be a bit underinflated by a few PSI.
The tire pressure monitoring system (TPMS) checks air pressure using small sensors inside the tire’s air stems. These sensors are meant to be helpful, but they’re not always perfectly accurate and can be off by about 2 PSI.
Although it might be tempting to ignore the blinking warning light, it’s not a good idea. When you see the light, the best thing to do is quickly check your tire pressure. Digital tire gauges are more accurate than those at many fuel stations. If your gauge shows you have 32 PSI in each tire (or you’re within 1 PSI of that number), you can ignore the light. But if you haven’t checked the tire pressure and you see the warning, it’s risky to ignore it. There might be a hole in one of your tires, so it’s smart to check.
If you add air and the problem keeps happening, visit a mechanic or tire shop to recalibrate the system. Also, check your tires monthly to keep them healthy and catch any issues early. The best time to check is in the morning or when your car hasn’t been driven for a few hours. The tires should be “cold” for the most accurate reading.
To prevent the warning light from coming on in the first place, there are a couple of things you can do :
- You can add a bit more air than the recommended pressure, like inflating to 35 PSI instead of 32 PSI. This can make your tires wear out a bit faster and make your ride a bit rougher, but it’s not a big difference. Some people find this to be a good solution.
- You can fill your tires with nitrogen instead of regular air. Nitrogen doesn’t expand or contract as much as regular air, and the machines that fill tires with nitrogen also remove water vapor from inside the tire. It’s the water vapor that can cause big pressure changes.