Patent ID: 8765844

Claim:
A manufacturing method of rubber composition, which is comprised of adding 40-110 mass parts of silica powders as reinforcing fillers to 100 mass parts of diene rubber component and adding silane coupling agent by 3-15 mass % of the silica powders, comprising: preparing styrene-butadiene rubber modified with a functional group(s) having hetero atom, as hetero-modified SBR, which is to make 20-95 mass % of said 100 mass parts or total of the diene rubber component, in the rubber composition, wherein said functional group(s) is at least one selected from the group consisting of hydroxyl group, amino group, carboxyl group, alkoxyl group, epoxy group, cyano group, and halogen group; preparing styrene-butadiene rubber having glass transition temperature in a range of −10° C. to 10° C. and having mass-average molecular mass of no less than 900,000, as high-Tg SBR, which is to make 5-25 mass % of said 100 mass parts or total of the diene rubber component, in the rubber composition; a first kneader-mixing step, at which 80-95 mass parts of the diene rubber component including at least 20 mass parts of the hetero-modified SBR is mixed with substantially all of the reinforcing fillers; taking out of obtained mixture from the kneader device to give a first master batch; and a second kneader-mixing step, in which the first master batch is mixed substantially solely with 5-15 mass parts of the high-Tg SBR, wherein the high-Tg SBR has a glass transition temperature in a range of −10° C. to 0° C.