maintenance September 22, 2017

Tire Pressure and Temperature Change

When it comes to tires, cold matters! Maybe you’ve been told to check your tire pressure once the weather gets colder. Perhaps you’ve been advised to check your tire pressure on “cold” tires. But what does temperature really do to tire pressure, and why does it make such a difference?

The answer lies in simple physics: warm air expands, and cold air compresses. Therefore, when the air in your tires is cold, it will read a lower psi (aka pounds per square inch – the way we measure tire pressure) and when it’s warmer, it will read higher. 

Always check psi on “cold” tires.

This has to do with the internal temperature of the air in your tires. Cold air will provide the lowest psi reading for your tires, which is the reading that really matters. When you drive a mile or more in your vehicle, the air in your tires will heat up enough to skew the reading to a higher psi. While the warm air’s psi is actually higher at the time, it’s a temporary pressure since the tires will eventually cool down and wind up with lower pressure later. Therefore, it’s best to check your tire pressure before they have been driven on at all (or no farther than a mile), or after you’ve let them sit for a few hours. This will ensure that your tire’s pressure is at a safe level from the very moment you start driving. 

Check psi when the weather gets cold

This advice has to do with the external temperature around your tires. When the temperature outside drops, it will cause the cold psi of your tires to be even lower. This means your tire pressure could very well be below the recommended level, often requiring the addition of air in order to maintain safe pressure levels. The general rule of thumb when comparing outside temperature to tire pressure is that for every 10◦ F of temperature change, the tire pressure will adjust by 1 psi. It’s quite common for the TPMS (link to TPMS blog) alert to light up on your dashboard on the first cold morning of the fall or winter seasons, before you’ve had time to adjust the pressure and add more air. Unless you have a legitimate problem with your tires, simply adding air and driving for a few minutes should cause the TPMS light to turn off. 

It’s a good idea to keep a high-quality tire pressure gauge in your car at all times. Checking your tire pressure monthly is ideal, but regardless of when you last checked, make sure to check again when the weather turns cold. You can click here (link to Tire Pressure 101 blog) to learn more about why tire pressure is so important, how to check your tire pressure, and some possible causes of tire pressure loss. At Wiygul Automotive Clinic, we want to make sure you stay safe on the road all year long. Stop in to any of our convenient locations and we’ll happily inspect, repair, or replace your tires as needed! 

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