Patent ID: 7789117
Filing Date: 2010-09-07
Classification: B60C,C08L

Abstract:
1. A tire having a rubber tread of a cap/base construction comprised of an outer, zoned rubber tread cap layer having an outer running surface and an underlying internal rubber tread base layer of a unitary rubber composition, wherein said tread cap layer is comprised of two adjoining circumferential, longitudinal tread cap rubber zones of graduated physical properties, wherein said tread cap zones individually extend from the running surface of said tread cap layer radially inward to said tread base layer: wherein said tread cap zones are comprised of a primary tread cap zone and a lateral, outboard control tread cap zone; wherein said primary tread cap zone spans from 70 to about 85 percent of the axial width of the free running surface of said tire tread cap layer and wherein said lateral, outboard control tread cap zone spans from about 15 to 30 percent of axial width of the free running surface of said tire tread cap layer and is positioned adjacent to and axially outward from said primary tread cap zone; wherein the storage modulus G′ at −25° C., 3 percent strain and 10 Hertz of the rubber composition of said primary tread cap zone is in a range of from about 10 to about 30 MPa and at least about 6 MPa less than such storage modulus G′ at −25° C. of said lateral, outboard control tread cap zone which is in a range of from about 25 to about 45 MPa; wherein the storage modulus G′ at 60° C., 3 percent strain and 10 Hertz of the rubber composition of said primary tread cap zone is in a range of from about 3.5 to about 5.5 and within about 2 MPa of such storage modulus G′ at 60° C. of said lateral, outboard control tread cap zone which is in a range of from about 2 to about 4 MPa; wherein the tan delta value at 100° C., 3 percent strain and 10 Hertz of the rubber composition of said lateral, outboard tread cap zone is in a range of from about 0.15 to about 0.35 and at least 10 percent greater than such tan delta value of the rubber composition of said primary tread cap zone which is in a range of from about 0.05 to about 0.25; wherein the rubber composition of said primary cap zone is comprised of, based on parts by weight per 100 parts by weight rubber (phr) and so long as said storage moduli G′ and tan delta values are met: (A) 100 phr of at least three conjugated diene-based elastomers comprised of: (B) reinforcing filler in a range of from about 90 to about 135 phr comprised of: (C) coupling agent for said silica having a moiety reactive with hydroxyl groups contained on the surface of said precipitated silica another moiety interactive with diene-based elastomers; wherein the rubber composition of said lateral outboard tread cap zone is comprised of, based on parts by weight per 100 parts by weight rubber (phr) and so long as said storage modulus G′ values are met: (D) 100 phr of at least three conjugated diene-based elastomers; (E) reinforcing filler in a range of from about 50 to about 120 phr, wherein the content of said reinforcing filler is at least 10 phr less than the content of reinforcing filler of the rubber composition of said primary tread cap zone, comprised of: (F) coupling agent for said silica having a moiety reactive with hydroxyl groups contained on the surface of said precipitated silica another moiety interactive with diene-based elastomers.