Tire tread rubber composition

1. A tire tread rubber composition comprising:

a. 100 parts of an elastomer component comprising:

i. at least 55 parts of two styrene-butadiene rubbers having a silica-reactive functional group,

ii. 20-45 parts of Hevea natural rubber, polyisoprene, or a combination thereof, and

iii. 0-5 parts of polybutadiene,

b. at least one reinforcing silica filler in an amount of 50-150 phr,

c. 11-40 phr of at least one hydrocarbon resin having a Tg of about 35 to about 60° C.,

d. less than 10 phr of oil, and

e. a cure package,

wherein (c) and (d) are present in a total amount of less than 50 phr.

2. The tire tread rubber composition of claim 1 , containing no more than 20 phr of carbon black filler.

3. The tire tread rubber composition of claim 1 , wherein (c) and (d) are present in a total amount of no more than 40 phr.

4. The tire rubber composition of claim 1 , wherein the two styrene-butadiene rubbers having a silica-reactive functional group have a Tg of about −65 to about −40° C.

5. The tire tread rubber composition of claim 1 , wherein (i) is present in an amount of 60-80 phr.

6. The tire tread rubber composition of claim 1 , wherein (c) and (d) are present in a total amount of no more than 25 phr.

7. The tire tread rubber composition of claim 1 , wherein (b) is present in a total amount of 50-89 phr.

8. The tire tread rubber composition of claim 1 , containing no more than 10 phr of reinforcing carbon black filler.

9. The tire tread rubber composition of claim 1 , wherein the hydrocarbon resin of (c) comprises an aliphatic resin, an aromatic resin, or a combination thereof.

10. The tire tread rubber composition of claim 1 , wherein the elastomer component includes 1-5 phr of polybutadiene rubber.

11. The tire tread rubber composition of claim 1 , wherein the reinforcing silica filler of (b) has a CTAB surface area of greater than 200 m 2 /g and a BET surface area of 150-350 m 2 /g.

12. The tire tread rubber composition of claim 1 , wherein the rubber composition has a value for tan δ at 60° C. of 0.09-0.23 and meets at least one of the following

a. has a value for tan δ at −30° C. of at least 2.5 times the tan δ at 60° C. value;

b. has a value for tan δ at 0° C. of at least 2.5 times the tan δ at 60° C. value; or

c. has a value for tan δ at 30° C. of at least 1.1 times the tan δ at 60° C. value.

13. The tire tread rubber composition of claim 12 , wherein each of (a), (b), and (c) are met.

14. A tire tread rubber composition comprising:

a. 100 parts of an elastomer component comprising:

i. at least 60 parts of two styrene-butadiene rubbers having a silica-reactive functional group and each having a Tg of about −65 to about −40° C., and

ii. 10-40 parts of Hevea natural rubber, polyisoprene, or a combination thereof,

b. at least one reinforcing silica filler in an amount of 50-89 phr,

c. 11-40 phr of at least one hydrocarbon resin having a Tg of about 35 to about 60° C.,

d. less than 10 phr of oil, and

e. a cure package,

wherein (c) and (d) are present in a total amount of no more than 25 phr and the composition contains no more than 10 phr of carbon black filler.

15. The tire tread rubber composition of claim 14 , wherein (i) is present in an amount of 65-80 phr.

16. The tire tread rubber composition of claim 15 , wherein the two styrene-butadiene rubbers) having a silica-reactive functional group of (i) have a Mw of 250,000 to 600,000 grams/mole.

17. The tire tread rubber composition of claim 14 , wherein the hydrocarbon resin of (c) comprises an aliphatic resin, an aromatic resin, or a combination thereof.

18. The tire tread rubber composition of claim 14 , wherein the rubber composition has a value for tan δ at 60° C. of 0.09-0.23 and meets at least one of the following

a. has a value for tan δ at −30° C. of at least 2.5 times the tan δ at 60° C. value;

b. has a value for tan δ at 0° C. of at least 2.5 times the tan δ at 60° C. value; or

c. has a value for tan δ at 30° C. of at least 1.1 times the tan δ at 60° C. value.

19. A tire tread rubber composition comprising:

a. 100 parts of an elastomer component comprising:

i. at least 60 parts of two styrene-butadiene rubbers having a silica-reactive functional group each rubber having a Tg of about −65 to about −40° C. and a Mw of 250,000 to 600,000 grams/mole,

ii. 20-35 parts of Hevea natural rubber, polyisoprene, or a combination thereof, and

iii. 0-5 phr of polybutadiene rubber,

b. at least one reinforcing silica filler in an amount of 50-89 phr,

c. 11-40 phr of at least one hydrocarbon resin having a Tg of about 35 to about 60° C.,

d. less than 10 phr of oil, and

e. a cure package,

wherein (c) and (d) are present in a total amount of no more than 40 phr and the composition contains no more than 10 phr of carbon black filler.

20. A tire including a tread comprising the tire tread rubber composition of claim 1 .

21. A tire including a tread comprising the tire tread rubber composition of claim 14 .

22. A tire including a tread comprising the tire tread rubber composition of claim 19 .