The air pressure gauge tool of the present invention provides an air gauge capable of accessing, loosening, removing, retaining, and reinstalling tire valve dust-caps as well as measuring tire pressure. A tire valve dust-cap engaging receptacle is attached to a conventional tire pressure gauge of the type having a cylindrical body. The dust-cap engaging receptacle is comprised of a socket-type cylindrical receptacle, with an open top end and parallel splines lining its internal circumference, for receiving and engaging a tire valve dust-cap.