Abstract: An air inflation system for tires on a vehicle having at least one driven axle in which the axle includes a longitudinal extending air passageway connected to each tire at the end of the axle and a rotatable air coupling connected between an air line and the air passageway. The coupling includes a stationary tubular sleeve surrounding the axle and first and second seals, respectively, at opposite ends of the sleeve in which the seals rotate with the axle and sealingly engage the axle. The seals are biased into engagement with the sleeve. Preferably, the ends of the sleeve and the coacting seals include beveled sealing surfaces.