A vehicular tire having integral tread and carcass portions molded into a closed, toroidal configuration and further formed into a convoluted shape, when uninflated, both for providing and facilitating its stretching over the outside diameter of a mounted wheel, and for positively controlling and urging movement of the carcass-inside diameter in an inward contracting direction only to a gripping position with either the specially contoured wheel rim or adapter ring element mounted thereto.