High speed heavy duty cross ply tire

A heavy duty high speed cross ply tire comprising at least one pair of bead cores, one of each of said at least one pair of bead cores being disposed in each bead portion of the tire,

• a carcass composed of a plurality of plies of cords laid at angles of 30 to 60 degrees with respect to the tire equator, each said carcass ply turned up around the bead cores to have turned up portions,
• said carcass plies including at least one ply of aromatic polyamide fiber cords,
• the twist coefficient TN of each said aromatic polyamide fiber cord being in a range of 2.466.times.10.sup.3 to 3.036.times.10.sup.3, wherein the twist coefficient TN is defined as the product T.sqroot.D of the cord twist number T (turns/10 cm) of the cord and the square root of the total denier number D (deniers) of the cord,
• each said carcass ply turned up portion provided with a cord spacing between the carcass cords therein and the cords of adjacent carcass plies,
• the radially outer edge of each said carcass ply turned up portion wrapped by an edge cover in such a way that:
• in an end region, the cord spacing being in a range of 0.25 to 2.0 times the diameter of the carcass cords, said end region defined as extending between the radially outermost edge of the carcass ply turnup portions and a point being radially inward thereof by a distance of 60% of the radial height of said radially outermost edge as measured from the bead base line;
• and in the remaining region other than said end region, the cord spacing being smaller than that in said end region and being in a range of 0.1 to 1.6 times said diameter of the carcass cords, said edge cover made of a rubber compound having a 100% modulus of 40 to 70 kgf/sq.cm, an elongation at rupture of 200 to 350%, a stress at rupture of 150 to 300 kgf/sq.cm, and a thickness of 0.2 to 2.0 mm.