A simple and frictionless pressure limiting valve assembly for use in pneumatic tire valves wherein a snap diaphragm is movable into and out of a sealing relationship with a valve member by means of the snap action of a snap action diaphragm. The snap action diaphragm may be biased by a means if desired to permit inflation of the pneumatic tire until a desired pressure is reached whereby the snap action diaphragm reverses itself and closes the air flow passageway. This inexpensive assembly only has a few parts. Some preferred embodiments are easy to incorporate (add to) in a conventional tire valve assembly and some others have their specific design. The effective point of activation of the snap action of the snap action diaphragm may be calibrated to precise values.