We all are. Literally! At sea level, the Earth’s atmosphere exerts 14.7 PSI (pounds per square inch) of pressure, so our bodies think that 14.7 PSI is completely normal; you’re completely unaware of this pressure that operates on and in you at all times.
In fact, we’re willing to bet that most people don’t think about air or atmospheric pressure at all … until that tire begins to look a little flat. Then it’s off to the gas station to top off the air in those skids.
A car tire generally requires a pressure of about 30 PSI. Of course, temperature has some effect on this, and that’s why it’s best to check your tire pressure either before you run your car or at least 6 hours after you’ve finished driving it. The reason for this is simple: the contact between the tires and the road generates a certain amount of friction, raising the temperature of the tire, and that change in temperature can give you a false read on the tire’s pressure.
If you’re not sure what number you’re shooting for when putting air in your tires, either check the sticker on the door of your car or consult the owner’s manual. While it’s tempting to use the pressure number that’s printed on the side of the tire itself, you don’t want to do that! That number indicates the maximum amount of pressure that the tire is equipped to handle, not the number for optimum performance of the tire.