PROTECTIVE TIRE SIDEWALL COATING
Tires having a sidewall that is covered with a protective coating that may cover the exposed surface of one or both of the sidewalls. The protective coating is a rubber composition that is based upon a cross-linkable elastomer composition that includes, per 100 parts by weight of rubber, ), between 25 phr and 45 phr of natural rubber, between 25 phr and 45 phr of polybutadiene rubber and between 30 phr and 40 phr of EPDM. Additionally the rubber composition may include between 20 phr and 50 phr of carbon black and a curing system. The curing system may be a peroxide curing system. In addition, the protective coating may be applied to the sidewall at a thickness of between 0.4 mm and 1 mm.
1 . A tire, comprising:
a tread supported by a crown, the crown being positioned radially inward of the tread, the crown including a belt package, each positioned radially inward of the tread;
a pair of bead sections arranged to face each other in a tire width direction, each bead section including a circumferentially-inextensible bead core and a toe guard that forms an external surface of the bead section;
a carcass layer constructed from a plurality of radially-oriented carcass layer cords embedded in an elastomeric matrix and extending through the crown and between the beads, the carcass layer ends being anchored in the pair of bead cores;
a pair of sidewalls, each sidewall extending radially-inward from an axial edge of the crown and extending toward the bead section, each sidewall defining a side of the tire, wherein the sidewall covers that portion of the carcass layer extending from the crown section to the bead section and is formed of a sidewall material; and
a protective coating covering an exposed surface of at least one of the pair of sidewalls, wherein the protective coating comprises a rubber composition that is based upon a cross-linkable elastomer composition, the cross-linkable elastomer composition comprising, per 100 parts by weight of rubber (phr):
between 25 phr and 45 phr of natural rubber;
between 25 phr and 45 phr of polybutadiene rubber;
between 30 phr and 40 phr of EPDM;
between 20 phr and 50 phr of carbon black; and
a curing system.
2 . The tire of claim 1 , wherein the protective coating is applied to the tire with a thickness of between 0.5 mm and 1.1 mm.
3 . The tire of claim 2 , wherein the protective coating is applied to the tire with a thickness of between 0.7 mm and 0.9 mm.
4 . The tire of claim 1 , wherein the protective coating on the tire after curing is between 0.4 mm and 1 mm thick.
5 . The tire of claim 4 , wherein the protective coating on the tire after curing is between 0.5 mm and 0.8 mm thick.
6 . The tire of any one of the preceding claims, wherein the sidewall covers at least a portion of the axial end of the tread, at least a portion of the toe guard or both.
7 . The tire of claim 1 , wherein the protective coating is applied to both an outer tire side of the sidewall and an inner tire side of the sidewall.
8 . The tire of claim 1 , wherein the cross-linkable elastomer composition comprises between 30 phr and 40 phr of the natural rubber.
9 . The tire of claim 1 , wherein the cross-linkable elastomer composition comprises between 30 phr and 40 phr of the polybutadiene rubber.
10 . The tire of claim 1 , wherein the cross-linkable elastomer composition comprises between 30 phr and 40 phr of the carbon black.
11 . The tire of claim 1 , wherein the sidewall material contains no staining antiozonant.