AUSTIN (KXAN) — Clear skies and calm winds overnight helped drop temperatures areawide into the 30s and 40s Wednesday morning. This was the coldest morning we have experienced since April. A record low temperature of 38 degrees was even set at Austin-Bergstrom International Airport.

Wednesday morning’s low temperatures (10/19)

You may have been one of the many who saw the low tire pressure warning light on your car’s dashboard turning on. This was more than likely the result of the big drop in temperatures that occurred between Tuesday afternoon’s high temperature of 70 down to Wednesday morning’s low temperature of 42 (nearly a 30-degree change).

Air is a gas that expands when it heats up and contracts when it cools down. Air particles are constantly moving around in our atmosphere. When air gets warmer, these air particles move around more quickly. When air gets colder, these particles slow down. Air pressure is the energy that is released when these particles collide.

For every 10-degree Fahrenheit change in temperature, you can expect a change in your tire pressure by about one-to-two pounds per square inch or PSI. A 30-degree temperature drop or increase, for example, could result in as much as a six PSI change in your tire pressure.

Why you should fill tires in the morning instead of the afternoon

Mornings, when it is typically cooler, give you the best gauge of what your tire pressure needs to be for the proper functioning of your vehicle. The PSI for your vehicle, which can be found in your owner’s manual or marked on the driver-side door, is always the recommendation of your tire pressure when in cooler air. Meaning, if your light turned on in the morning, it is best to fill it up as soon as you can. If you wait until the afternoon when temperatures have warmed significantly, the PSI will increase and may cause the light to turn off.

Why you should fill up your tires as soon as possible

When the air pressure is low in your tire, more of the tire’s tread or surface is touching the road. This creates greater friction, causing the tire to heat up, which can create premature wear and tear on the tire. This in return will also decrease the gas mileage of your vehicle.