Disclosed is a tire/wheel assembly which, even in a case of forming a run-flat support member by processing a metal material high in breaking strength, realizes the forming without generating wrinkles and cracks. In the tire/wheel assembly, a run-flat support member is inserted into a cavity portion of a pneumatic tire mounted onto a rim, a run-flat support member being formed of an annular shell having an arched cross-section, and elastic rings attached to bent ends of the annular shell in an inner peripheral side thereof In the tire/wheel assembly, while plural notches are provided in the bent ends along a circumferential direction thereof, a length Ln (mm) of the notches in the circumferential direction is set between 1.0 mm and 15.0 mm inclusive, and a ratio Ws/Wg of a width Ws (mm) of the bent ends of the annular shell to a thickness Wg (mm) of the elastic rings is set between 0.55 and 0.92 inclusive.