Q. I put air in my tires yesterday and had all the tires at the same pressure. My question is that if the tires are in direct sunlight, will that increase tire pressure? I have two tires that were in the shade and two tires in the sun. The tires that were in the shade were the same pressure that I had filled them up with. The two tires in the shade were 1½ pounds heavier. Is that because of the sun hitting the tires?
A. Temperature has a big effect on the air pressure in tires, so what happened to you makes sense. The sun heated up the tires on that side of the car and the tire pressure went up. When you check the tire pressure you always want to set it first thing in the morning to the cold tire pressure, as the day warms up the tire pressure will go up.
Tires have to be checked periodically, especially when we go through a change of season, which we'll be doing soon. As colder weather sets in, you could see the tire pressure drop by as much as 5 pounds per square inch.
Don't forget, low tire pressure is a big drag on fuel economy, so it's good that you are keeping them set properly.
Check the spare
When was the last time you checked your spare tire, or checked to see if the jack and lug wrench is in the car and if it works? You would not want to find out that the tire is flat or the jack is missing the day you need it. Preventive maintenance will always save you time and money in the long run.