A device to prevent the full collapse of a pneumatic tire on vehicles and large aircraft includes three arcuate portions for cooperatively fitting over a tire rim to provide an underlying support surface for a tire carcass subsequent to losing air or gas pressure. The three arcuate band portions releasably couple together for mounting on the drop well of a tire rim to form a substantially continuous surface. The invention also has protective coverings removably disposed on the outer radial extent of the band portions. The protective coverings are provided with frictional means for engaging the inner wall of the tire to prevent circumferential or lateral displacement of the tire carcass during rotation of the wheel. An insert may be placed between the band and the drop well to position the band.