| 摘要 |
PROBLEM TO BE SOLVED: To provide a rubber composition for tire treads making abrasion resistance compatible with heat build-up properties at much higher levels than those of conventional compositions and to provide a pneumatic radial tire for trucks/buses using the composition. SOLUTION: The rubber composition is obtained by compounding 100 pts.wt. of a diene rubber with 30-50 pts.wt. of carbon black having 110-130 m<SP>2</SP>/g CTAB (cetyltrimethylammonium bromide) adsorption specific surface area,≥0.85 24M4DBP (compressed DBP oil absorption)/CTAB adsorption specific surface area and≥1.05 N<SB>2</SB>SA (nitrogen adsorption specific surface area)/IA (iodine adsorption). The pneumatic radial tire for the trucks/buses is prepared by using the rubber composition in a cap rubber and has≥12 MPa 300% tensile stress of both the cap rubber and the base rubber measured at 80°C. Loss tangents tanδc and tanδb of the cap rubber and the base rubber measured at 80°C satisfy the relationship of 0.12>tanδc>tanδb, respectively. Furthermore, the ratio of the thickness of the base rubber to the whole thickness of the tread rubber is set within the range of 0.20-0.50. COPYRIGHT: (C)2007,JPO&INPIT
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