| 摘要 |
PURPOSE:To make improvements in steering safety and driving comfortableness at both dry and wet roads, by specifying each of area ratios and angles or the like at each groove, in case of asymmetric block patterns that set up each subgroove of plural straight grooves on a tire tread. CONSTITUTION:On a tire tread, there are provided with plural straight grooves 1 as annular from in the tire circumferential direction E-E' from each straight groove 1 are set up there as well, whereby each block m is formed. in the abovementioned asymmetric block patterns, a groove area ratio of a half (a) of the radial inside at the time of being installed in a vehicle is set to be 1.2 to 1.4 times over a groove area ratio of a half (a) at the radial outside. And, an angle thetac to the tire circumferential direction E-E' of a subgroove 2c at the central part in the radial direction is set to a range of 45 to 75 degrees. In addition, an angle thetas to the tire circumferential direction E-E' of a subgroove 2s at both ends in the radial direction is set to a range of 65 to 90 degrees, and it is made larger as much as more than 5 degrees than the angle thetac of the subgroove 2c. |
