Valve stem-based pressure regulator system for an air maintenance tire and method

An air maintenance tire assembly and a method of maintaining air in a tire is disclosed. The assembly comprises a tire having a tire cavity bounded by first and second sidewalls extending to a tire tread region and air pumping means for generating pressurized air for maintaining air pressure within the tire cavity at a preset pressure level. The has an elongate valve stem projecting outward from the tire cavity and operative to admit pressurized air into the cavity through a valve stem internal air passageway. The assembly further comprises an elongate shaft having an longitudinal axis, the shaft being reciprocally moveable axially within the valve stem internal air passageway between a passageway-opening axial position and a passageway-closing axial position, and a pressure regulator operative to move the elongate shaft axially between the passageway-opening and passageway-closing positions responsive to a detected air pressure level within the tire cavity.