Rubber composition for use in tire tread comprising a rubber component, carbon black and process oil

A rubber composition for use in tire treads, comprising:

• (A) a rubber component containing at least 30% by weight of a conjugated diene-monovinyl aromatic hydrocarbon copolymer which is prepared using an organic lithium compound as an initiator, wherein the percentage of vinyl bonds in the conjugated diene units in the copolymer molecules is from 55 to 85% and the content of the monovinyl aromatic hydrocarbon units in the copolymer molecules is from 25 to 40% by weight,
• (B) from 80 to 180 parts by weight of carbon black filler with respect to 100 parts by weight of the rubber component, wherein said carbon black filler has an average particle size of not more than 300 .ANG., and
• (C) from 50 to 200 parts by weight of process oil with respect to 100 parts by weight of the rubber component, wherein said process oil has a viscosity specific gravity constant of from 0.900 to 0.999,
• wherein said rubber composition has a 200% tensile modulus of from 5 to 50 kgf/cm.sup.2 and a temperature integrated value of the loss tangent, ##EQU7## of from 30 to 56.