Sumitomo Rubber Industries Limited

Narihiro Tahara

Mamoru Uchida

Shinichi Miyazaki

Naohiko Kikuchi

Masafumi Otani

Hidehiko Hino

Kiyoshi Funahara

Takeshi Ohta

Rolling resistance performance, high-speed-durability performance, and cornering performance are simultaneously realized at high levels. A two-wheeled automotive vehicle tireincludes a tread portion having an outer surface that extends so as to be curved such that the outer surface is convex outward in the tire radial direction, and is arc-shaped. A tread rubberG includes a center rubber CR, shoulder rubbers SH, and middle rubbers MD. The center rubber CR includes a center cap layer CRc and a center base layer CRb. A loss tangent tan &#x3b4;b of the center base layer CRb and a width Lb thereof in the tire axial direction are each limited so as to be set within a predetermined range.

Two-wheeled automotive vehicle tire

There is provided a rubber composition for a tire tread having a remained despersibility of reinforcing agents without increased rubber hardness, an improved performance on snow and ice road, and an improved abrasion resistance, and inhibited from increasing in hardness or inhibited from increasing in hardness with the passage of time. A rubber composition for a tire tread, which comprises (a) a diene rubber, (b) glass fibers, (c) a reinforcing agent, and 1 to 15 parts by weight of (d-1) inorganic powders having a Mohs hardness of less than 6.5 and an average particle-size of less than 25 &#x3bc;m and/or (d-2) silicone rubber powders based on 100 parts by weight of the diene rubber.

Rubber composition for tire tread

There is provided a studless tire that is excellent especially in performance on a snow or ice road. A studless tire, wherein non-metal staple fibers having an average fiber diameter of 1 to 100 &#x3bc;m and an average length of 0.1 to 5 mm are dispersed in a diene rubber in such a way that the non-metal staple fibers are oriented in a thickness direction of a tread, a complex elastic modulus Ein the thickness direction of the tread and an elastic module Ein a circumferential direction of the tire measured at 25&#xb0; C. satisfy the equation 1.1&#x2266;E/E&#x2266;4, and hardness of the tread rubber measured at &#x2212;10&#xb0; C. is 45 to 75 degrees.

Studless tire having tread including fibers oriented in thickness direction

A studless tire contains tread portion made of vulcanized rubber, compounded from 100 parts by weight of rubber and 2 to 30 parts by weight of short fibers, and the tread portion has a ground connecting region with sipes, formed by pressing thin plates onto the tread rubber during vulcanizing, whereby the thin plates orient the short fibers in a radial direction. Preferably, the short fibers have a diameter of not more than 30 &mgr;m and a length of from 0.3 to 20 nm, and the thickness of the thin plates or the width of the sipes ranges from 0.2 to 0.5 mm with spacings being sipes less than 10 mm. The short fibers are circumferentially oriented before pressing the thin plates, and the total length in mm of axial component of all sipes ranges from 0.05 to 0.15 times the area in mm of ground contacting region.

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Kobe, Japan

Narihiro Tahara