Why Do I Lose Tire Pressure When It’s Cold Outside?

Have you noticed, the last few days, that your tire pressure is down?  Why is that? Well. pretty simple. Your tires support the weight of your car, right? Nope. It's the air pressure inside your tire that supports the weight.

Since air is a gas, it expands
when it's hot and contracts
when it's cold. That's why your
tire pressure drops when it's cold.
Especially when it's as frickin' cold as it's been lately. The most accurate reading is the cold reading. Warm air reading is artificial. So always go with the cold air reading

The rule of thumb is that with every 10 degree Fahrenheit change in air temperature, tire pressure will change about 2%. Up with higher temps and down with colder temps. So, it you drive a car,van or light truck, You'll change about one psi. per 10 degree temperature change.

It's very important to check you tire pressure often to get the maximum performance and wear from your tires.