| 摘要 |
Tread rubber composition for tires, which is prepared by the use of rubber components consisting, when the weight of the rubber components is assumed to be 100 parts, of 20 to 80 parts of a diene rubber and 80 to 20 parts of a styrene-butadiene copolymer having a glass transition temperature of from -50.degree. to -25.degree.C and satisfying a relation shown by an equation of 4.8X-Y ~ 32, in which a bonded styrene content is represented by X % by weight and a 1,2-bond content in butadiene portion is represented by Y % by weight. Also in the tread rubber composition of the present invention, the temperature dispersion curve of a tan .delta. of the rubber composition has plural peaks, the temperature difference between the highest temperature side peak thereof and a single peak of the rubber composition prepared by using the above-mentioned styrene-butadiene copolymer alone as a rubber component is within 10.degree.C , and the tan .delta. measured at 50.degree.C is 0.08 to 0.20. The tread rubber composition can provide tires having a low rolling resistance and an excellent grip characteristic on a wet road surface.
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