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Why Do Tires Lose Pressure In Cold Weather?

MINNEAPOLIS (WCCO) -- As the weather gets colder, drivers might notice the tire pressure light going off in the car. It's common as winter settles in.

So why do our tires go flat in cold weather? Good Question.

Just because the warning light comes on doesn't mean the tire is losing air. The more likely culprit is the colder air, which is denser than warm air.

"It's kind of like a balloon when it gets colder, they shrivel up and shrink," says Nate Anderson, owner of Steve's Auto World in Maple Grove.

For every 10-degree drop in temperature, tires lose one to two pounds of pressure – or PSI. That can cause problems while driving.

"You get worse fuel economy, it also wears out your tires faster, and you get worse traction on ice," Anderson said.

Since 2007, all cars are required to have tire pressure monitoring systems. But, for people with older cars, the recommendation is to check the tire pressure every few weeks in the cold.

Generally, the pressure is found on the inside of the driver's side door. Anderson says the warning systems generally go off when a car's tires fall 5 PSI below the recommended levels.

Anderson says the best time to check your tire pressure is when the car has been sitting outside. Driving the vehicle around could warm up the tires, so the reading could be off.

Many gas stations and services stations have free air pumps, which include their own gauge so a driver knows the proper amount of air to pump.

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