Sumitomo Rubber Industries Limited

Sumitomo Chemical Company, Limited

Toru Fukumoto

Keisaku Yamamoto

Mitsuji Tsuji

Kizuku Wakatsuki

Yuichi Saito

Tadao Matsumoto

Chieko Aoki

Yasuo Igarashi

Kazuaki Yarimizu

Ryozo Okada

Kazuhiro Hirose

Gaku Tanaka

Shuji Imaoka

A pneumatic tireincludes a pair of beadsand a carcassextending on and between both beads. Each beadincludes a core. The coreincludes: a main bodyincluding a cordextending in a circumferential direction; and a stretchable portionformed from a crosslinked rubber. The stretchable portionis located inward of the main bodyin an axial direction. The stretchable portionhas a size with which at least one cross-section of the cordcan be included therein in a cross-section of the bead. Preferably, in the tire, the main bodyincludes a hard unit and a soft unit. The soft unit is located outward of the hard unit in a radial direction. A hard cord of the hard unit stretches more easily than a soft cord of the soft unit.

Pneumatic tire having bead core with stretchable portion

A motorcycle tire comprises: a toroidal carcass comprising two carcass plies of cords arranged at an angle of from 20 to 80 degrees with respect to the tire circumferential direction; and a band comprising at least one ply of at least one helically wound cord disposed radially outside the carcass. The band cord is made of steel filaments of 0.08 to 0.20 mm diameter twisted together into a L&#xd7;M&#xd7;N structure. The band cord has a low tensile elastic modulus range and a high tensile elastic modulus range, wherein an inflection point between the low tensile elastic modulus range and the high tensile elastic modulus range lies between 2% elongation and 7% elongation of the cord, and a tensile force required to cause 2% elongation of the band cord is not more than 60 Newton.

Motorcycle tire and method for manufacturing the same

A motorcycle tire for uneven terrain travel including two carcass plies, at least one of which is aramid plyusing aramid fiber cordobtained by subjecting N (2 to 4) bundlesof aramid fiber 'f' to final twist, the aramid fiber cordhaving a total fineness D of 2,200 to 5,010 dtex and a twist factor T represented by the equation (1):&#xd7;(&#x221a;{square root over ()})&#xd7;&#x2003;&#x2003;(1)in which n is the number of final twists per 10 cm of the cord (unit: time), and D is a total fineness of the cord (unit: dtex),the twist factor falling within the range of:

Motorcycle tire for uneven terrain travel

A method of manufacturing a rubber coated fabric for a tire which includes a weft cutting step of cutting a weft of the rubber coated fabric base substance using a cutting device at a cut pitch Cp of two to five times an arrangement pitch P of a warp. The cut ductility of the weft is set between 5 and 20%. The cutting device utilizes first and second rollers in which the peripheral protrusions and the peripheral grooves are alternately formed. Groove widths Wand Wof the peripheral grooves of the first and second rollers are set between 2.0 and 5.0 mm, protruding widths Tand Tof the peripheral protrusions of the first and second rollers are set to 0.25 to 0.5 times the groove widths Wand Wand the insertion depths hand hof the peripheral protrusions to the peripheral grooves are set between 2.0 and 4.0 mm.

Method of manufacturing fabric with rubber for tire

A radial tire for motorcycle has a belt layer of cords with modulus of elasticity of 600 kg/mm.sup.2 or more wound spirally on a carcass nearly parallel to the tire equator, and a bead apex rubber disposed on a bead core between a carcass main portion extending from a tread to a bead core and a carcass turned up portion. The bead apex rubber consists of a soft apex part SA with JISA hardness of 50 to 60 degrees extending radially outward from the bead core, and a hard apex part HA with JISA hardness of 70 to 95 degrees extending radially outward from the soft apex part SA. A height h1 the soft apex part SA from a bead base is 0.20 to 0.40 times a height h0 of the tread end, and a height h2 of the hard apex part HA is 0.50 to 1.25 times the height h0 of the tread end.

Radial tire for motorcycle with two part bead apex

A rubber composition for tire treads comprising a rubber component consisting essentially of (A) 20 to 100% by weight of a solution-polymerized styrene-butadiene copolymer rubber having a Mooney viscosity ML.sub.1+4 of 30 to 200 at 100.degree. C. prepared by copolymerization of styrene, butadiene and a polyvinyl aromatic compound followed by coupling with a trifunctional or tetrafunctional coupling agent, and (B) 0 to 80% by weight of at least one rubber selected from the group consisting of an emulsion-polymerized styrene-butadiene rubber, a butadiene rubber, natural rubber and a synthetic polyisoprene rubber; and (C) 50 to 250 parts by weight of a carbon black having an iodine adsorption number of not less than 60 mg/g and an oil absorption of not less than 110 ml/100 g per 100 parts by weight of said rubber component; the tan .delta. peak temperature Tg of the cured product of said rubber composition being from -40.degree. to +5.degree. C. The tread rubber composition can be processed without causing bagging with a good dispersibility of carbon black and provides tires having a low rolling resistance and a high grip characteristic.

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Kobe, Japan

Toru Fukumoto