Once you know which proper pressure for your tires is, you are ready to check them. In order to do this, you must unscrew caps on tire air valve and press tire pressure gauge against it. You should make sure you keep tire pressure gauge as firmly against tire valve as not to let air come out from it.

Once you have tire pressure gauge connected with tire valve, gauge will immediately tell you what tire pressure is. This will allow you to learn weather tire needs more air or its air pressure is correct. If it needs more air, you should do it carefully in order not to pass its air limit. And, in case its air pressure is correct, you simply need to disconnect air pressure gauge from it and screw valve cap back in its place.

Newer cars have different air filters than older ones. If your car is rather new, its air filter is probably rectangular and you might find it located under hood, near radiator area or fender wells. In order to change it, you must open it and take actual air filter from it, replacing it by new and then closing it again.

If your car is older, then air filter will probably be of a big round shape and located near engine area. It might probably be screwed, and all you might need to do is to unscrew cover, let air filter come out, and place new one instead of it. You must pay attention in case it has any other attachment mechanisms such as clips which you would need to take off as well.