A pressure equalizing valve for pneumatic tires including a visual display is described which is ideally suited for use with dual tires. A cylindrical housing accommodates a spring biased diaphragm mounted in a first chamber. The diaphragm carries a valve member thereon and acts as a sealing member or element to close two air passageways which are in communication with the dual tires in a conventional dual tire installation. The valve member closes the air passageways when a pre-adjusted and calibrated value of air pressure is lost by the dual tires involved. Changes in the air pressures acting on the spring biased diaphragm are communicated to a diaphragm follower on the atmospheric side of the diaphragm. A visual display is operated with the diaphragm follower and responds at an eight to one ratio to the movement of the diaphragm and follower when air pressure changes occur and a resultant movement of the diaphragm and follower occurs.