It's that time of year again folks. You may be heading out the door early in the morning this week, especially today and Monday morning, and notice a big temperature swing from a day or days before. We were just in the mid 70s yesterday and we've already dropped into the 50s for Sunday. It doesn't stop there, we'll be dropping back down near freezing Monday morning, so seeing that your low tire pressure light on your dashboard is possible. Is it a flat tire? Probably not. Leak? Also not the main culprit. A lot of the time, weather is to blame for your low tire pressure light coming on when there is a decrease in temperature, but why?
Tire pressure can decrease about 1 PSI (pounds per square inch) for every 10 degrees the temperature drops. It's not due to air leaking out, but instead it's the air inside the tire condensing, taking up less space when it's cold. This is temporary, because driving will heat up the tire and increase the tire's pressure.
A lot of the reasoning behind why this happens is because of the molecules inside the tire. Cooler air molecules can take up less space inside your tire and exert less force on tire walls. As temperature drops, molecules slow down. When it’s hot, molecules will move faster and increase tire pressure.
Image Courtesy: NWS
Again, a great example of this will be Saturday heading into Monday. As a cold front rolled through our area, we will end up going from highs in the mid 70s on Saturday afternoon to temperatures on Monday morning in the low to mid 30s. So, temperatures dropped about 40 degrees meaning the PSI in your tires dropped around 4 or more PSI.Â
Even if you don't think it is a tire leak and just the cold weather, it can still make way for dangerous conditions on the roadways, so checking your tire pressure often is always recommended.Â
