Stretchable radial spare tire

A stretchable tire, comprising:

• (a) at least one carcass ply reinforced with radially oriented cords disposed at angles in the range of from 75-90 degrees relative to a centerplane containing the mid-circumferential centerline of the tread of the tire when the tire is molded, vulcanized and uninflated in a storage shape, said cords of said carcass ply being highly elongatable in an amount of from 50 to 100 percent to allow for toroidal expansion of the tire to an inflated operating shape;
• (b) a fluid impervious innerliner disposed at the radially inner surface of said tire within said carcass ply;
• (c) a tread and pair of sidewalls surrounding said carcass ply and terminating at a pair of annular beads;
• (d) at least one belt ply of cords interposed between said carcass ply and tread for annularly reinforcing the tire, said cords of said belt ply being disposed at angles in the range of from 0-30 degrees measured from said centerplane when the tire is molded, vulcanized and uninflated in said storage shape, and also being highly elongatable in an amount of from 50 to 100 percent to allow for circumferential expansion of the tread upon inflation of the tire to said inflated operating shape;
• (e) each of said reinforcement cords of said carcass ply and said belt ply consisting of a central core and at least one inextensible yarn spirally wrapped around said core, the tensile strength of said core being sufficient prior to being subjected to temperatures of vulcanization to maintain said inextensible yarn in helical relation during building of the tire and shaping to said storage shape from an unvulcanized cylindrical shape;
• and
• (f) said core being of a material having a sufficient reduction in tensile strength when subjected to temperatures of vulcanization of the tire to permit the stretching out of said yarn after the tire is vulcanized and during expansion of the tire from said deflated storage shape with said yarn in the spirally wrapped condition to said inflated operating shape with said yarn in the stretched out condition.