A support belt comprising a support member positioned inside a tubeless tire and extending circumferentially about the rim on which the tire is mounted for engaging the tire when it is deflated to prevent the rim from damaging the sidewalls and tread portion of the tire wherein the support member comprises a continuous band encircling the rim and releasably secured or positioned relative thereto by means which are adapted to release when the weight of the vehicle is imposed on the support member upon deflation of the tire to enable the support member to thereafter freely move radially and circumferentially relative to the rotating rim to inhibit damage to the deflated tire.