Auto Talk 101: How to fill Air in Tires - as part of the expert series by GeoBeats. Filling tire pressure is a pretty simple process. The first thing you have to determine is what is proper inflation for your tire. There are two numbers and most people do not realize this. There is what we call operating pressure and there is what we call maximum pressure. What it says on the side of the tire is maximum pressure. This one says maximum inflation 44 PSI. What that means is that is the maximum amount of air you can put in that tire without jeopardizing the structural integrity of the tire. That is not where you should inflate your tire. You should inflate your tire to operating pressure which is determined by the car manufacturer. So I looked on the tire sticker which is on the door. It is also in your owners manual and the operating pressure on this car is 30 pounds, even though the maximum inflation for this tire is 44 pounds. A lot of people make this mistake and over inflate. We are going to set this one at 30 pounds. You take your little cap off, and if your cap is ever missing you can buy a 4 pack of these at any auto parts store for just a couple of dollars and it is well worth replacing them. And then again a tire gauge, fairly simple, you can buy a tire gauge for a couple of dollars at most any department store or auto parts store and then you can check your tires yourself. And you just push that on there and you will see the little gauge runs out and this one is at about 31 pounds. So, we want 30, 31 is fine, it is okay to be a pound or two on either side of the actual inflation that you want. And that is it. If it is okay, you put your cap back on and you go to the next tire. If it is a little low, you can use the air hose at the local gas station or, you know, wherever you are going to go and you just put a little air in there if it is low. If it is over-full, which this one now is, there is a little knob on the back and you can just push down on the center of there and let a little bit out, and now we are right back at 30 pounds where we want to be.