Abstract: A tire inflator includes a pressure vessel filled with non-flammable compressed gas. A tubular valve housing is secured within the inflator outlet and includes radial ports opening to the bore of the housing and located adjacent an outer apertured end wall. A tubular valve body is slidable within the housing bore and includes a conventional tire valve. The inner ends of the housing and valve body each include a slightly raised rib in concentric relationship. A rupturable diaphragm secured to the ribs locates the valve body relative to the housing and seals the space therebetween. Over pressure in the vessel ruptures the diaphragm between the valve body and housing and moves the valve body outwardly into engagement with the end wall of the housing. The pressure fluid within the pressure vessel escapes to atmosphere through the space between the valve body and housing and through the radial ports.