If you drive a car, you should know what a valve cap is and where it's located if you ever check the air in your tires. Some kids like to collect valve caps, and you might find one missing on your car one day. There are some new types of valve caps designed to keep them on the valve stem called anti-theft valve caps. Unfortunately, although they keep the valve caps from being stolen, you might not be able to inflate your tires if you lose the key.
Examine the valve cap to see what type of key it uses. Some of the anti-theft devices use an Allen wrench key, while others use a special sleeve-type socket.
Try the different Allen wrench sizes in the small hole in the cap until you find the one that fits tight. Detach the set screw by turning the Allen wrench counterclockwise. If it is the other type, move on to the next step.
Try different size sockets over the valve cap until you find one that will fit tightly over the cap. Use your small hammer to tap it on snugly. Turn the socket counterclockwise until the cap comes off, using your pliers.
