Patent ID: 8084565

Claim:
A rubber composition for tires, comprising: (a) 10-90% by weight of a high-cis polybutadiene derived from polymerization of 1,3-butadiene in the presence of a catalyst comprising (A) an yttrium compound, (B) an ionic compound including a non-coordinate anion and a cation, and (C) an organometallic compound including an element selected from the groups 2, 12, 13 of the periodic table; (b) 90-10% by weight of a diene-based rubber other than the (a) high-cis polybutadiene; and (c) 1-100 parts by weight of a rubber reinforcer mixed in 100 parts by weight of a rubber component (a)+(b); the high-cis polybutadiene comprising a cis-1,4-polybutadiene having 90% or more of a cis-1,4 structure.