| 摘要 |
PURPOSE:To improve the traction and braking efficiencies of the tire in the caption on the snow road by providing land portions continuing netlikely and polygonal recesses enclosed by the land portions, specifying the depths of the recesses, and forming grooves having specific depths on the bottom surfaces of the recesses. CONSTITUTION:A tread pattern 3 provided on the tread 2 of a tread rubber 1 is constituted from land portions 4 continuing netlikely and a large number of polygonal recesses 5 enclosed by the land portions 4. Also, longitudinal grooves 7 are formed on the bottom surfaces 6 of the recesses 5, and short sub-grooves 8 divided from the grooves 7 in the orthogonal direction to the same are formed on said bottom surfaces 6. Each of the bottom surfaces 6 of the recesses 5 is provided at the position of which depth from the tread surface is 0.3-0.5 times the thickness of the tread rubber, and each of the depths of the grooves 7 is set at 0.5-0.9 times the thickness of the tread rubber in measurement. Thereby, the rigidity of the land portions 4 can be maintained sufficiently though the recesses 5 are enlarged in area, and as a result it is possible to ensure the excellent traction efficiency on the snow road. |
