ROCHESTER, NY (WROC) — Every year, all it takes is one cold morning and suddenly your dashboard lights up with a warning: “Low Tire Pressure.” Not only is it distracting to have a warning light on your dashboard, but it’s also hurting your gas mileage too.
To answer the obvious, no, your tires don’t have a leak (probably). The real reason why your tire pressure goes down in cold weather has to do with how the air in your tire behaves when the temperatures change.
In warmer weather, the air molecules vibrate quickly because they have more energy. This causes them to bounce around and become more spread out pushing up against the inside of the tire creating higher pressure. When the temperatures drop, however, the air molecules don’t move as fast and push closer together. Since the air isn’t as spread out anymore, there’s now less of them pushing up against the inside of the tire, meaning there’s not as much pressure.
For example, let’s say you filled your tires up to 32 PSI when it was 60 degrees out. A few days later the temperature tanks to 30 degrees. For every 10 degrees the temperature drops, and you generally lose about 1 PSI. Now instead of 32 PSI, you’ll be sitting at 29 PSI and likely, especially in a newer vehicle, have a message waiting for you on your dashboard.
That explains why your dashboard is lit up, but it doesn’t answer why your gas mileage is affected. The answer is fairly simple as well…since the tire isn’t as inflated due to low pressure, more of it is in contact with the ground as you drive. This in turn increases the amount of friction between your car and the ground, forcing your engine to have to push more power to the wheels in order to keep the same speed.
More power, means more gas being used over a shorter distance. This means your gas mileage is going to start trending down if you don’t reinflate your tires to where they’re supposed to be. According to the Department of Energy, on a set of properly inflated tires, gas mileage can improve anywhere from 0.6 to 3.0%. While that doesn’t sound like a lot, over time the savings add up. In addition to that, your tires will last longer if properly inflated, and your stopping distance will also improve. Saving you money in the long run and making your everyday drives a little bit safer.