What Is Ideal Tire Pressure in Cold Weather?

Cars typically require a tire pressure of 30 to 35 psi (pounds of force per square inch). The recommended psi for your car is the ideal tire pressure year-round; there aren’t different numbers for summer or winter. But temperature does affect tire pressure. So when the temperature drops, you might need to inflate your tires more often to maintain ideal tire pressure in cold weather.

How Does Cold Weather Affect Tire Pressure?

When outdoor temperatures drop significantly, so does the pressure in your tires. That’s because cold causes air molecules to slow down and stick together, resulting in a drop in air pressure and a potentially underinflated tire. Conversely, when it’s hot outside, warmer air molecules move around faster, bumping into each other more and raising the tire pressure to a potentially overinflated level.

Many tire manufacturers, such as Firestone and Goodyear, estimate that tires lose one psi for every 10 degrees the outside temperature drops. If your car has a Tire Pressure Monitoring System, the warning light will be triggered by at least a 25 percent drop in tire pressure. This is especially useful for keeping track of tire pressure in cold weather.

Checking Tire Pressure in Cold Weather

Check your tires after your car has been parked for at least three hours. (Driving raises the air temperature and therefore the air pressure in the tires.) Your car’s ideal tire pressure is usually listed inside the driver-side door and in the car’s owner manual. A common mistake is to fill tires to the max pressure listed on the sidewall, instead of what’s recommended by the auto manufacturer. Also, be sure to check the recommended pressure for the front and rear tires in case they’re different.

Insert a pressure gauge into the tire air valve swiftly and firmly for an accurate reading. Then, immediately replace the air valve cap to avoid letting out any air. If your tires are below the recommendation for your car, use an air compressor to inflate them until you get the right reading.

It’s best to check your tires once a month, but you might need to check your tire pressure more often in cold weather. Other signs that your tires might be underinflated:

• They look flatter than usual;
• The steering wheel shakes;
• It takes longer to come to a stop when braking.

Don’t Be Tempted to Drive on Underinflated Tires

There’s a school of thought in snowier locales that underinflated tires are better for driving on snow because the tires will make more contact with the surface. While that’s technically true, it’s never safe to intentionally drive with low tire pressure, even in cold weather.

That’s because when tires are underinflated, the sidewalls flex more, resulting in poor handling. The car won’t turn as responsively and feel like it’s swaying around corners. Under-inflated tires also expose the softer sidewall to road imperfections, which can cause them to puncture, says Chris Pyle, an auto expert with JustAnswer.com.

“The center of the tires also cup up, causing the sides of the contact surface to wear but not the center,” he says. “Basically, the tires wear faster, your MPG will be less, and it can be dangerous to you and others on the road.”

Underinflated tires also cause more friction with the road, which causes them to wear faster and also heat up. That can weaken the tire structure and increase the likelihood of a blowout, says Justin Dugan, brand ambassador at American Trucks. “They also provide less stability, making it harder to control the vehicle, especially during turns or emergency maneuvers, which increases the risk of accidents,” he says.

All in all, driving with too low of tire pressure makes you three times more likely to be in a collision related to tire issues, according to a 2012 study by the National Highway Traffic Safety Administration.

Should you be concerned about over-inflating tires in the winter?

Yes. Overinflating tires generally causes them to wear out prematurely and can lead to unexpected blowouts. In the winter, driving on over-inflated tires is also particularly dangerous because it reduces traction.

“With over-inflated tires, less of the tire makes contact with the road, which can be especially risky on icy or snowy surfaces,” says Dugan.

About the Experts

• Chris “Moose” Pyle is a master-certified technician with 20-plus years of automotive experience. He has also worked as an expert for JustAnswer.com since 2006, where he answers hundreds of car maintenance and repair questions a day.
• Justin Dugan is a brand ambassador at American Trucks and has worked as an automotive writer and TV host since 2011.