Combination radial tire for heavy load vehicles

Claim 1

A combination radial tire for heavy load vehicles comprising; a carcass composed of at least two plies including polyester fiber cords arranged in a plane containing a rotational axis of the tire or inclined at an extremely small angle with respect to said plane, all plies of said carcass being wound around a bead core from the inside toward the outside thereof to form a turn-up portion, a rubber stock disposed on the bead core and interposed between the carcass itself and the turn-up portion thereof, and at least one bead portion reinforcing layer arranged along the turn-up portion of the carcass and including cords crossed with the cords of the turn-up portion of the carcass, at least one additional reinforcing layer arranged at the lower half region of the carcass itself along said rubber stock wherein a lower end of said at least one additional reinforcing layer is fixed to said bead core, said additional reinforcing layer interposed at least between said plies of the carcass itself and/or between said carcass itself and said rubber stock, said additional layer including aromatic polyamide textile cords which are substantially in parallel with said carcass ply cords, and said additional reinforcing layer extending along said carcass itself over a region having a vertical height measured from the bead base and corresponding to 15% to 45% of a tire height measured from the same bead base.