To suppress the deformation of a bead core and the fretting of a carcass cord, while suppressing blowing-through of the carcass cord, in a bead wind structure.

A ply fold-back part 6b of the carcass 6 is composed of a main portion 10 curving along a side surface S1 in a bead core 5, an inner surface SL, an outer side surface So; and a sub portion 11 extending while tilting toward a ply body portion 6a near an outer surface SU of the bead core 5. The periphery of the bead core 5 is coated by a reinforcement rubber layer 13 made from high elastic rubber which is 0.5 to 3.0 mm in thickness ta and 20 to 70 Mpa in complex elastic modulus E*a. At a near position Q, the thickness T0 of rubber at a gap portion G between bead wire 5w and the carcass cord 20 is not less than 0.7mm. In the gap portion G, a cushion rubber layer 14 made from low elastic rubber having complex elastic modulus E*b smaller than the complex elastic modulus E*a and wherein a difference (E*a-E*b) is not less than 10Mpa is interposed between the reinforcement rubber layer 13 and the carcass cord 20.

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