| 摘要 |
PURPOSE:To enhance controllability, wear-resistance, rolling resistance, and low-temperature running performance of the captioned tire, which contains steel belts and which has designated oblateness, by specifying both glass- transition temperature and compounding ratio of the tread rubber. CONSTITUTION:The base rubber of a tread rubber of a radial tire, which contains steel belts and which has the oblateness of 60% and under, is formed with the following three constituents: (1) styrene-butadiene (30-80% weight part) whose glass transition temperature is -20--40 deg.C, (2) styrene-butadiene (10-60% weight part) whose glass transition temperature is -40--60 deg.C, and (3) butadiene rubber (10-20% weight part) whose glass transition temperature is lower than -80 deg.C. Taking the weight part of this base rubber as 100, sulphur with 1.7-4.5pts.wt. and carbon black, whose iodine adsorption number is 80-150mg/g and whose oil absorption is 70-140ml/100g (60-120pts.wt.), are blended with the base rubber. With this compounding ratio, the tire performance including controllability can be enhanced without impairing the gripping performance.
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