An air-maintenance tire system includes a compression actuator mounted to the tire carcass configured for operative actuation by tire deformation during a tire revolution, a pump assembly affixed to the tire carcass and including a compressor body affixed to the compression actuator and having an internal air chamber, the air chamber having an inlet opening for admitting air into the internal air chamber and an outlet opening for conducting air from the internal air chamber to the tire cavity. The air compressor body further includes a piston valve member and an outlet valve member located within and at opposite respective ends of the internal air chamber, the piston valve member and the outlet valve member moving within the internal air chamber responsive to actuation by the compression actuator between respective open and closed positions, whereby cyclically opening and closing the inlet and the outlet openings during an air compression cycle. The compression actuator includes a hollow containment body formed from a resilient deformable material composition and containing a quantity of a non-compressible medium. The containment body is affixed to a relatively high flex-deformation region of the tire carcass and reciprocally transforms between a deformed state and a non-deformed state to generate a compression force against a piston valve member surface and move the piston valve between the open and closed positions within the air chamber.