with cords inclined at angles of 15 u00b0 or less preferably at 0 u00b0 relative to the equatorial plane of the tire in accordance with the present invention the carcass ply 12 is formed from a cord 30 as seen in fig2 the cord 30 is a composite cord made of filament yarns of appropriate stress strain characteristics to provide the tire with additional bending resistance when the tire operates in run flat mode the cord 30 is formed of at least one low modulus yarn 32 about which is twisted at least one high modulus yarn 34 the construction of the yarn allows the lower modulus component of the yarn 30 to work at relative low strain i e the inflated tire mode until the cord has reached an allowable elongation from which point only the high modulus component will be under tension i e the run flat tire mode and will limit the stretch of the cord possible reinforcing materials for either the high or low modulus yarns include but are not limited to aramid polyethylene ketone pk polyphenylene 2 6 benzobisoxazole pbo rayon polyester polyamide polyethylene terephthalate pet polyethylene napthalate pen and polyvinyl alcohol pva preferably the high modulus yarns are formed from aramid pk pva or pbo while the low modulus yarns are formed from rayon nylon polyester pet or pen the final material selection is.