Abstract: An apparatus is provided for mounting on a wheel rim a deflated run-flat type tire which has been loosely preassembled on the wheel. The apparatus includes a wheel support for accommodating the preassembled tire and wheel and retaining same in a horizontal plane. A locking member coacts with the wheel support and locks the preassembled tire and wheel in the horizontal plane. An upright post is fixed a predetermined radial distance from the wheel support and is radially spaced from the periphery of the accommodated tire and wheel. A clamp device is mounted for vertical and transverse adjustment on the upright post and is adapted to clamp a segment of the beaded inner edge of the tire sidewall against a portion of a flange formed on the rim of the accommodated wheel. An installer unit is mounted at a selected elevated position relative to the accommodated tire and wheel and is adapted to be manually rotated intermittently about the axis of the accommodated wheel.