A self-inflating tire assembly comprises a tire having a tread region, first and second sidewalls, and first and second bead regions, wherein the first and second sidewalls extend respectively from the first and second bead regions to the tread region, wherein the tread region and the first and second sidewalls enclose an annular tire cavity. Further, the assembly comprises an air passageway connected to one of the sidewalls and extending essentially in a circumferential direction of the tire for pumping air from outside of the tire into the tire cavity, wherein the air passageway has an air passageway inlet for receiving air from outside of the tire and an air passageway outlet for releasing air into the tire cavity. Moreover, the assembly comprises an air pressure regulator having an air pressure regulation chamber, a connector end, and a channel fluidly connecting the pressure regulation chamber with the connector end, wherein the air pressure regulator is detachably connected to one of the air passageway inlet and the air passageway outlet via the connector end for allowing fluid communication between channel and the air passageway via the connector end. In addition, the invention relates to a pressure regulator kit for regulating the pressure of a tire, the kit comprising a plurality of air pressure regulators.