| 摘要 |
PURPOSE:To improve the performance on snow, ice, or on a lubricious road face at the last stage of abrasion by having three of more main grooves continuous in the circumferential direction of a pneumatic tire for heavy load and a total of four-two narrow and two extremely narrow-sub grooves continuous in the circumferential direction of the tire, and specifying the rigidity of each pattern block divided by these grooves into the numerical value within a specified range. CONSTITUTION:Three main grooves composed of the main groove 2 on the meridian face S-S of the tread face 1 of a pneumatic studless tire for heavy load and the main grooves 3 and 3 positioned symmetrically about the meridian face are extended in circumferential direction while meandering a little zigzag each to right and left with depth of 20mm, and circumferential grooves 4 and 4 are arranged with width narrower than the main groove and in analogous shape to the main grooves, being caught between the main grooves 2 and 3, at the right and left of the meridian face. Furthermore, circumferential grooves 5 and 5 with extremely narrow width are arranged at both ends of the tread face 1 of the tire, and when defined that the length in circumferential direction of the block is I, that the length in width direction is b, and that the depth of the narrow groove is h, these fulfills 4.0<0.684XbX(I<3>/ h<3>)X(1/[1+15.6X(I<2>X4h<2>)])<6.0. |
