Patent ID: 8835545

Claim:
A rubber composition for use in tire treads comprising: 100 parts by mass of a diene rubber and from 75 to 95 parts by mass of a silica, wherein the diene rubber comprises from 70 to 90 mass % of a terminal-modified styrene-butadiene rubber having a hydroxy group on an end of the molecule and wherein the terminal-modified styrene-butadiene rubber comprises 20 mass % to 40 mass % styrene, and from 10 to 25 mass % of a butadiene rubber wherein the vinyl bond content in a butadiene moiety of the terminal-modified styrene-butadiene rubber is from 35 to 75 mass %; the silica has a BET specific surface area of from 194 to 225 m 2 /g, a CTAB specific surface area of from 180 to 210 m 2 /g, a particle size distribution width L d ((d 84 −d 16 )/d 50 ) of at least 0.91, wherein V (d5-d50) /V (d5-d100) is at least 0.66; and a durometer hardness of the rubber composition when measured at 20° C. is from 70 to 75; the rubber composition further comprises a carbon black having a nitrogen specific surface area (N 2 SA) of from 70 to 100 m 2 /g, the total amount of the carbon black and the silica being from 75 to 120 parts by mass per 100 parts by mass of the diene rubber; and the rubber composition further comprises a softener, the amount of the softener being from 25 to 40 parts by mass per 100 parts by mass of the diene rubber.