Abstract: A pneumatic tire assembly is capable of supporting a vehicle wheel rolling for a limited distance when the air in the assembly has escaped. The tire of the assembly is prevented from going completely flat by an annular insert, preferably of a high modulus elastomeric material, that is placed inside the tire and fits over the wheel rim and between the beads of the tire. The annular insert is of a novel construction that is lightweight and flexible enough to be stretched over a conventional rim, yet is able to support the load normally borne by the inflated tire and also resists unseating of the beads.