Tire rubber composite and pneumatic tire

A rubber composition for tires comprising:

• per 100 parts by weight of diene rubber containing from 5 to 50 wt. % of solution polymerization-produced terminally modified styrene-butadiene rubber (modified S-SBR) having a vinyl unit content of 25 wt. % or greater and a glass transition temperature of −50° C. or lower, from 2 to 50 parts by weight of an aromatic modified terpene resin having a softening point of 100° C. or higher, and a total content of 60 to 130 parts by weight of two types of silica, that is silica X and silica Y;
• a functional group of the modified S-SBR being a functional group having reactivity with a silanol group on a surface of the silica selected from the group consisting of a hydroxyl group-containing polvorganosiloxane structure, an alkoxysilyl group, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, an imino group, an epoxy group, an amide group, a thiol group, and an ether group;
• a proportion of the silica relative to a total amount of a reinforcing filler containing the silica and a carbon black being 85 wt. % or greater;
• a nitrogen adsorption specific surface area of the silica X being 140 m2/g or greater;
• a nitrogen adsorption specific surface area of the silica Y being greater than 100 m2/g and less than 140 m2/g;
• and if a compounded amount of the silica X relative to 100 parts by weight of the diene rubber is x parts by weight and a compounded amount of the silica Y relative to 100 parts by weight of the diene rubber is y parts by weight, a relationship x/7<y≦x being satisfied.