Patent ID: 8002007
Filing Date: 2011-08-23
Classification: B60C,Y10T

Abstract:
1. A pneumatic radial tire for heavy loads comprising: a pair of bead portions in each of which a bead core is embedded; a radial carcass extending from one bead portion to the other bead portion and turned around the bead core from an inner side to an outer side of the bead portion in a width direction of the tire to be anchored; and a rubber chafer disposed over the radial carcass in the opposite side of the bead core and extending at least from the inner side of the bead core in the width direction of the tire toward a side portion of the tire, wherein a cross-sectional shape of the bead core in the width direction of the tire is a polygon having a first side part located innermost in a radial direction of the tire and a second side part radially outwardly extending from a first end part which is an outer end of the first side part in the width direction of the tire; an angle formed by a bead sheet portion of a regular rim and the first side part when the tire is mounted on the regular rim is within 2 degrees; a wire chafer is provided at a region around an outer side of the radial carcass corresponding to a first section and a second section as viewed in the width direction of the tire, the first section lying at least from a central part of the first side part in the width direction of the tire to the first end part; and the second section lying from the first end part to a second end part which is an outer end of the second side part in the radial direction of the tire; and an angle θ formed by a cord of the wire chafer and a cord of the radial carcass is within a range between 35 degrees and 60 degrees in the first section and within a range between 40 degrees and 65 degrees in the second section; and wherein the cross-sectional shape of the bead core in the width direction of the tire is a hexagon, in which the first side part and an opposite side part thereof are parallel; the wire chafer is provided at a region around an outer side of the radial carcass corresponding to at least one of a third, forth, fifth and sixth section; the third section lying from the second end part to a third end part which is an outer end of the opposite side part in the width direction of the tire; the forth section lying from the central part of the first side part to a forth end part which is an inner end of the first side part in the width direction of the tire; the fifth section lying from the forth end part to a fifth end part which is an inner end in the width direction of the tire; and the sixth section lying from a sixth end part which is an inner end of the opposite side part in the width direction of the tire to the fifth end part; the angle θ formed by the cord of the wire chafer and the cord of the radial carcass is within a range between 35 degrees and 50 degrees in the third section, within a range between 30 degrees and 55 degrees in the forth section, within a range between 40 degrees and 55 degrees in the fifth section and within a range between 45 degrees and 65 degrees in the sixth section; and the angle θ varies among the first to sixth section.