Abstract: A pneumatic tire, after manufacture, is provided with a propellant material and a foam forming sealant material in its interior pressurizable space. The propellant and sealant are isolated from each other during normal running conditions of the tire and have no significant effect on the normal running characteristics of the tire. When a tire fails due to a puncture or the like, a loss of tire pressure and/or collapse of the tire structure and/or heat build up in the bead area due to friction permit the propellant and the foam forming materials to interreact.In one embodiment of the invention the propellant and sealant are enclosed in separate chambers of a plurality of dual-chamber containers secured to the bead portion of the tire and/or a rim base. In other embodiments a plurality of mono-chamber containers house one of the materials, the other material being uncontained in the pressurizable space.