Abstract: The present invention is an improvement to a tire mounted air pressure gauge for use on vehicles having inflatable tires. The air pressure gauge has a dial face, with a coiled pressure responsive spring expandable to indicate the pressure detected by the gauge. The gauge is mounted directly onto the valve stem of a tire to detect the pressure in the tire, or is mounted onto the valve steam via an L-shaped conduit. The conduit contains a lug adapted to depress the conventional valve core of the valve stem and release air pressure within the valve stem and tire. An arc-shaped or cylindrical retainer is provided on the dial face to limit radial expansion of the coiled spring due to centrifugal forces of the rotating tire and other jarring forces exerted on the pressure gauge during use of the tire.