Kabushiki Kaisha Bridgestone

Daisuke Tamura

The invention controls irregular wear in the shoulder land portions and reduces the occurrence of cracking in the shoulder grooves of a pneumatic tire. To that end, the groove wall surface () on the shoulder land portion () side of the shoulder groove () has an inclined surface consisting of a first inclined part () inclined toward the equatorial plane of the tire at an inclination angle &#x3b8;, which is constant along the circumference of the tire, and a second inclined part () further inclined from the first inclined part () toward the equatorial plane of the tire and reaching the groove bottom () of the shoulder groove () at an angle &#x3b1; with respect to the first inclined part (), which varies along the circumference of the tire. Also, the inclination angles of the first and second inclined parts () are set such that the maximum value &#x3b1;and the minimum value &#x3b1;of the angle &#x3b1; satisfy (D&#x2212;d) (tan &#x3b1;&#x2212;tan &#x3b1;)&#x2267;2.5 where D is the depth from the tread face to the bottom of the shoulder groove (), d is the depth from the tread face to the boundary position between the first inclined part () and the second inclined part (), &#x3b1;is the maximum value of the angle &#x3b1;, and &#x3b1;is the minimum value of the angle &#x3b1;.

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Kodaira, Japan

Daisuke Tamura