| 摘要 |
PURPOSE:To improve durability of bead to ply end exfoliation so as to prevent lack of a bead toe part by specifying a range of modulus value in 100% extension and break extension value of chafer rubber which covers a surface part from the inside to the outside in the axial direction of a tire bead part. CONSTITUTION:Specification of characteristic values of two kinds of chafers can improve exfoliation performance of ply ends and prevent defects of a bead toe part 4 without spoiling rim abrasion resistance. In a pair of tire bead parts in which both ends of a carcass ply composed of a plurality of codes, which are arranged parallel in the approximately perpendicular direction to the tire meridian direction, are wound around bead wire bunches positioned in left/right sides of the tire axial direction respectively, modulus M100 in 100% extension of chafer rubber 2 and break extension Eb after thermal aging are selected in the range of 40kg/cm<=M100, 230%<=Eb respectively and at the same time sulfur content added to the chafer rubber is set within 1.0wt. or more. |
