| 摘要 |
PROBLEM TO BE SOLVED: To effectively improve lateral rigidity without increasing vertical rigidity by restricting the rotation of bead cores to maintain high tensile strength of a carcass. SOLUTION: An insulation rubber layer 7 is provided between two carcass plies 6A, 6B in a bias structure. The insulation rubber layer 7 includes a core covering portion 7A having a thickness T of 0.2-1.0 mm and ranging over along the inner and outer faces 5a, 5b of a bead core 5 in a tire axial direction and the lower face 5c in a tire radial direction. The 100% modulus Mi of the insulation rubber layer 7 is 150-300% of the 100% modulus Mc of a topping rubber of a carcass 6 and the JISA rubber hardness HSi of the insulation rubber layer is 115-150% of the JISA rubber hardness HSc of the topping rubber.
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