Tire tread compound

A pneumatic tire having an outer circumferential tread wherein said tread is a sulfur-cured rubber composition comprised of, based on 100 parts by weight of rubber, (a) from about 30 to about 80 parts of an isoprene-butadiene diblock rubber, said isoprene-butadiene diblock rubber being comprised of a butadiene block and an isoprene-butadiene block, wherein said butadiene block has a number average molecular weight which is within the range of about 25,000 to about 350,000, wherein said isoprene-butadiene block has a number average molecular weight which is within the range of about 25,000 to about 350,000, wherein said isoprene-butadiene diblock rubber has a first glass transition temperature which is within the range of about -100.degree. C. to about -70.degree. C., wherein said isoprene-butadiene diblock rubber has a second glass transition temperature which is within the range of about -50.degree. C. to about 0.degree. C., wherein said isoprene-butadiene diblock polymer has a Mooney ML-4 at 100.degree. C. viscosity which is within the range of about 50 to about 140, and wherein the repeat units derived from isoprene and 1,3-butadiene in the isoprene-butadiene block are in essentially random order;

• and (b) from about 20 to about 70 parts of a second rubber selected from the group consisting of high vinyl polybutadiene rubber and styrene-isoprene-butadiene rubber.

A pneumatic tire having an outer circumferential tread wherein said tread is a sulfur-cured rubber composition comprised of, based on 100 parts by weight of rubber, (a) from about 50 to about 75 parts of an isoprene-butadiene diblock rubber, said isoprene-butadiene diblock rubber being comprised of a butadiene block and an isoprene-butadiene block, wherein said butadiene block has a number average molecular weight which is within the range of about 25,000 to about 350,000, wherein said isoprene-butadiene block has a number average molecular weight which is within the range of about 25,000 to about 350,000, wherein said isoprene-butadiene diblock rubber has essentially one glass transition temperature which is within the range of about -100.degree. C. to about -70.degree. C., wherein said isoprene-butadiene diblock polymer has a Mooney ML-4 viscosity at 100.degree. C. which is within the range of about 50 to about 140, and wherein the repeat units derived from isoprene and 1,3-butadiene in the isoprene-butadiene block are in essentially random order;

• and (b) from about 25 to about 50 parts of a second rubber selected from the group consisting of emulsion styrene-butadiene rubber and solution styrene-butadiene rubber.

A pneumatic tire having an outer circumferential tread wherein said tread is a sulfur-cured rubber composition comprised of, based on 100 parts by weight of rubber, (a) from about 50 to about 75 parts of an isoprene-butadiene diblock rubber, said isoprene-butadiene diblock rubber being comprised of a butadiene block and an isoprene-butadiene block, wherein said butadiene block has a number average molecular weight which is within the range of about 25,000 to about 350,000, wherein said isoprene-butadiene block has a number average molecular weight which is within the range of about 25,000 to about 350,000, wherein said isoprene-butadiene diblock rubber has a first glass transition temperature which is within the range of about -100.degree. C. to about -70.degree. C., wherein said isoprene-butadiene diblock rubber has a second glass transition temperature which is within the range of about -50.degree. C. to about 0.degree. C., wherein said isoprene-butadiene diblock polymer has a Mooney ML-4 at 100.degree. C. viscosity which is within the range of about 50 to about 140, and wherein the repeat units derived from isoprene and 1,3-butadiene in the isoprene-butadiene block are in essentially random order;

• and (b) from about 25 to about 50 parts of a second rubber selected from the group consisting of emulsion styrene-butadiene rubber and solution styrene-butadiene rubber.