A method of assembling an air pump in a tire is provided including: opening an axial air passageway of an elongate flexible air tube at one end; inserting one by one a plurality of one-way check valves into the air passageway from the one end to form an axial array of spaced apart check valves along the air passageway, each check valve having an external nominal width greater than a nominal width of the air tube passageway; establishing a press fit engagement between each check valve and air tube internal sidewalls defining the air passageway to place each check valve at a respective preferred position within the air passageway; retaining the check valves in the respective preferred positions within the air passageway by radial pressure from the air tube internal sidewalls and closing the one end of the flexible air tube.