Abstract: A pressure detector system for vehicle tires, within each tire, a pressure detector/transducer for sending a signal reflecting a under-inflation condition in the tire, receiving antennas, placed adjacent to each tire, a visual display of the under-inflated tire, each tire valve having an enlarged pedestal, the pressure detector/transducer mounted within pedestal, a main air passage bore communicating with the air chamber and with the reference chamber, an outer valve core and a inner valve core having a sealing valve stem extending the length of the valve core, biased upwardly, the reference chamber having a deformable wall which moves outwardly when the air pressure within the air chamber falls below the air pressure in the reference chamber, the deformable wall having an electrical contact mounted on the exterior side, a rigid wall spaced apart from the deformable wall, having an electrical contact facing the electrical contact on the deformable wall, when the air pressure in the air chamber falls, the two