| 摘要 |
PURPOSE:To improve the kinetic characteristic of the tire on a marshy road by designing the both edge parts of a straight groove provided at a particular position between the center in the circumferential direction of a tire treading surface and treading surface ends to have a specified depth and inclination. CONSTITUTION:The straight groove 8 is positioned in a zone within 50% of a distance (f) from the center CL in the circumferential direction and the end T on the tire treading surface 6. The edge part of the straight groove 8 is bevelled within a range from 20% to 60% of the groove depth (d) and the bevel inclination angle alpha is set within a range from 30 deg. to 60 deg.. If the straight groove is arranged at any position more than 50% of the distance T from the center of the treading surface and the treading surface end, the grove width (a) is reduced to a great extent, so that the drainage of the tire running on a marshy road becomes inferior, and therefore, the kinetic characteristic of the tire on the marshy road is degraded. Thus, by setting the distance ratio of the position (e) of the straight groove and the treading surface end T, e/f, to be less than 50%, even when a load is generated in the transverse direction, for example, by cornering of the vehicle, the ratio of reduction of width (a) of the straight groove can be minimized sufficiently. Thus, the kinetic characteristic of the tire running on the marshy road can be much improved. |
