Rubber composition for use in tires

1. A rubber composition for use in tires comprising:

from 60 to 120 parts by weight of a silica having a CTAB specific surface area of from 80 to 170 m 2 /g and from 3 to 20 parts by weight of an aromatic modified terpene resin excluding terpene phenol resins per 100 parts by weight of a diene rubber comprising from 30 to 80 weight % of a terminal-modified styrene-butadiene rubber and from 10 to 50 weight % of a butadiene rubber;

wherein the total of the terminal-modified styrene-butadiene rubber and the butadiene rubber is from 60 to 100 weight % based on the amount of the diene rubber, the terminal functional group of the terminal-modified styrene-butadiene rubber is a hydroxy group or an N-methylpyrrolidone group, the average glass transition temperature of the diene rubber is −55° C. to −70° C., the average glass transition temperature of a compound formed from the diene rubber, the aromatic modified terpene resin, and an optional oil component-containing plasticizer is from −45° C. to −60° C., the hydroxy value of the aromatic modified terpene resin is from 0 to 25 KOH mg/g, and the glass transition temperature of the aromatic modified terpene resin is from 20 to 80° C.

2. The rubber composition for use in tires according to claim 1 , further comprising a terpene phenol resin having a hydroxy value of from 0 to 20 KOH mg/g as the plasticizer, wherein the compounded amount (B) of said terpene phenol resin is adjusted so that, in relation to a compounded amount (A) of the aromatic modified terpene resin, the weight ratio B/(A+B) is 0.9 or less.

3. The rubber composition according to claim 2 , wherein the weight ratio B/(A+B) is from 0.1 to 0.7.

4. The rubber composition for use in tires according to claim 1 , comprising from 60 to 100 parts by weight of the silica.

5. The rubber composition for use in tires according to claim 1 , further comprising a silane coupling agent in an amount of from 3 to 15 weight % with respect to the amount of the silica.

6. The rubber composition for use in tires according to claim 5 , wherein the silane coupling agent is from 4 to 10 weight % with respect to the amount of the silica.

7. The rubber composition according to claim 1 , wherein the diene rubber comprises an amount of styrene from 14 to 40 weight %.

8. The rubber composition according to claim 7 , wherein the diene rubber comprises an amount of styrene from 20 to 35 weight %.

9. The rubber composition according to claim 1 , wherein the diene rubber comprises an amount of vinyl from 10 to 75 weight %.

10. The rubber composition according to claim 9 , wherein the diene rubber comprises an amount of vinyl from 30 to 70 weight %.

11. The rubber composition according to claim 1 , wherein the average glass transition temperature is from −55 to −65° C.

12. The rubber composition according to claim 1 , wherein the diene rubber comprises from 15 to 45 weight % of the butadiene rubber.

13. The rubber composition according to claim 1 , comprising from 5 to 20 parts by weight of the aromatic modified terpene resin per 100 parts by weight of the diene rubber.

14. A rubber composition for use in tires comprising:

from 60 to 120 parts by weight of a silica having a CTAB specific surface area of from 80 to 170 m 2 /g and from 3 to 20 parts by weight of an aromatic modified terpene resin excluding terpene phenol resins per 100 parts by weight of a diene rubber comprising from 30 to 80 weight % of a terminal-modified styrene-butadiene rubber and from 10 to 50 weight % of a butadiene rubber;

wherein the total of the terminal-modified styrene-butadiene rubber and the butadiene rubber is from 60 to 100 weight % based on the amount of the diene rubber, the terminal functional group of the terminal-modified styrene-butadiene rubber is a hydroxy group or an N-methylpyrrolidone group, the average glass transition temperature of the diene rubber is −55° C. to −70° C., the average glass transition temperature of a compound formed from the diene rubber and the aromatic modified terpene resin is from −45° C. to −60° C., the hydroxy value of the aromatic modified terpene resin is from 0 to 25 KOH mg/g, and the glass transition temperature of the aromatic modified terpene resin is from 20 to 80° C.

15. A rubber composition for use in tires comprising:

from 60 to 120 parts by weight of a silica having CTAB specific surface area of from 80 to 170 m 2 /g and from 3 to 20 parts by weight of an aromatic modified terpene resin excluding terpene phenol resins per 100 parts by weight of a diene rubber comprising from 30 to 80 weight % of a terminal-modified styrene-butadiene rubber and from 10 to 50 weight % of a butadiene rubber; and

an oil component-containing plasticizer;

wherein the total of the terminal-modified styrene-butadiene rubber and the butadiene rubber is from 60 to 100 weight % based on the amount of the diene rubber, the terminal functional group of the terminal-modified styrene-butadiene rubber is a hydroxy group or an N-methylpyrrolidone group, the average glass transition temperature of the diene rubber is −55° C. to −70° C., the average glass transition temperature of a compound formed from the diene rubber, the aromatic modified terpene resin and the oil component-containing plasticizer is from −45° C. to −60° C., the hydroxy value of the aromatic modified terpene resin is from 0 to 25 KOH mg/g, and the glass transition temperature of the aromatic modified terpene resin is from 20 to 80° C.

16. A studless tire using the rubber composition for use in tires according to claim 1 in a tread portion.