| 摘要 |
PURPOSE:To improve durability at belt portion, uneven abrasion performance and manuevering stability, by specifying a cord angle of a belt layer between central region and shoulder region, number of cords to be implanted and the lateral length of the cross-section of tire in the central region. CONSTITUTION:In belt layers composed of metallic cords, the cord angle of first belt layer 31 near to a carcass ply is set to 40-75 deg., while the cord angle of second and third belt layers 32, 33 is set to 10-30 deg. and the cord angle of fourth belt layer 34 is set to 10-30 deg.. Ratios of average cord angles theta1, theta2 and average numbers of cores to be implanted N1, N2 in central region A1 and shoulder region A2 of the second and third belt layers 32, 33 are set within predetermined ranges shown by formula I. Lateral length of the cross-section of tire in the central region A1 is set to be 0.40-0.60 times of the developed width of tread. With such arrangement, durability at the belt portion, uneven adrasion performance and manuevering stability can be improved.
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