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.
