| 摘要 |
A shoulder rib (3) is provided with a thin groove (4) continuously extend ing in the circumferential direction of the tread of a pneumatic tire. A cir cumferentially continuous annular groove (8), contiguous to the bottom of th e thin groove (4), is provided in a groove wall (4a) that is on the equatori al surface side of the tread in a cross-section in the lateral direction of the tread.The shape of the annular groove in a cross-section taken in the la teral direction of the tread is formed such that a corner contiguous to a gr oove wall on the equatorial surface side of the tread is rounded to a curvat ure radius R1, a corner at a portion on the outer side, in the radial direct ion of the tire, of a deep end portion of the annular groove is rounded to a curvature radius R2, a corner at a portion on the inner side, in the radial direction of the tire, of the deep end portion of the annular groove is rou nded to a curvature radius R3, and a corner contiguous to a groove wall (4b) on the tread end side is rounded to a curvature radius R4. Stone trapping r esistance, tear resistance of defense grooves, and groove bottom crack resis tance are increased. |
