| 摘要 |
PURPOSE:To improve running performance on a snowy and general road surfaces, by a method wherein a tread part is formed of minimum two layers and a tread side and an inner surface side are formd of rubber having a predetermined property of matter respectively. CONSTITUTION:A tread part 3 is formed of minimum two layers of rubber layers 31, 32, and the tread side rubber layer 31 is formed of rubber whose 100% modulus at a temperature of -20 deg.C is less than 32kg/cm<2> and hundredfold of the product of a tangential loss at a temperature of -20 deg.C and a reciprocal of the absolute value of 100% modulus at a temperature of -20 deg.C is equivalent to 1.80 or larger. The inner surface side rubber layer 32 is formed of rubber whose 100% modulus at a temperature of -20 deg.C is either equivalent to 32kg/cm<2> or larger. In this instance, it is desirable that the tread rubber layer 31 holds up to 50% of a depth of a tread groove. With this structure, running performance on a snowy and general road surfaces can be improved. |
