Rubber composition for a tire and tire using the same

#This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 2003-399317; 2004-32136; 2004-34797; 2004-105483 & 2004-237206 filed in Japan on Nov. 28, 2003; Feb. 9, 2004; Feb. 12, 2004; Mar. 31, 2004 & Aug. 17, 2004; respectively, the entire contents of which are hereby incorporated by reference.

#The present invention relates to a rubber composition for a tire and a tire using the same.

#In tread rubber of high performance tires such as racing tires, usually both high gripping performance and abrasion resistance are required.

#The rubber composition for a tire of the first embodiment of the present invention comprises a rubber component, a low molecular weight aromatic vinyl-conjugated diene copolymer, a resin and a softening agent and/or a plasticizer.

#The rubber component comprises an aromatic vinyl-conjugated diene copolymer having aromatic vinyl content of 20 to 60% by weight. The upper limit of the aromatic vinyl content is preferably 50% by weight. When the aromatic vinyl content is less than 20% by weight, sufficient gripping performance cannot be obtained. When the aromatic vinyl content is more than 60% by weight, not only does abrasion resistance decrease but also temperature dependency increases and as a result, the influence of temperature change on performance becomes large.

#Herein, examples of the aromatic vinyl component in the above aromatic vinyl-conjugated diene copolymer are vinyl aromatic hydrocarbon monomers such as styrene, α-methylstyrene, 1-vinyl naphthalene, 3-vinyl toluene, ethyl vinyl benzene, divinyl benzene, 4-cyclohexyl styrene and 2,4-trimethyl styrene. These can be used alone or two or more can be used together. Of these, styrene is preferable. Examples of the conjugated diene component are 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene and 2-phenyl-1,3-butadiene. These can be used alone or two or more kinds can be used together. Of these, 1,3-butadiene is preferable.