Abstract: A combined gauge and inflator for a tire includes a support member threaded on the tire stem with a body slidably disposed within the support member and locked in a first position. The body has a passage extending therethrough with a spring-biased piston slidably disposed therein. With the body in the first position, the piston rests against a spring-biased plunger, which opens the valve in the tire stem when the plunger spring is overcome. The plunger spring is overcome either by an air chuck acting on the piston to move the piston against the plunger or when the body is moved from its first position to a second position in which the body engages the plunger. When the body is moved against the plunger, sealing means on the piston seal the body passage so that air pressure in the tire moves the piston relative to the body. A scale on the piston cooperates with a marker on the body to indicate the pressure of the tire.