A pneumatic tire includes: a rim cushion rubber disposed in a bead portion where the bead portion and a rim are in contact with each other; an electrically conductive rubber disposed in the rim cushion rubber, the electrically conductive rubber having an electrical resistance value lower than that of the rim cushion rubber, and including a first end exposed on an outer surface of the rim cushion rubber in contact with the rim, and a second end disposed in contact with a tire component adjacent to the rim cushion rubber; and an earth tread rubber disposed in a tread portion passing through a cap tread rubber and an undertread rubber of the tread portion, the earth tread rubber having an electrical resistance value lower than that of the cap tread rubber.

The pneumatic tire includes: a belt layer, a belt reinforcing layer, a tread portion, sidewall portions, a rim cushion rubber, and an electrically conductive rubber disposed in the rim cushion rubber and includes a first end in contact with a rim and exposed on an outer surface of the rim cushion rubber and a second end in contact with a tire component adjacent to the rim cushion rubber. The electrical resistance value of the electrically conductive rubber and a portion of the tread portion is 1×10.sup.6 Ω or less. The electrical resistance value of the tire component, a coating rubber of the belt layer, and a coating rubber of the belt reinforcing layer is from 1×10.sup.6 Ω to 1×10.sup.8 Ω. The electrical resistance value of the rim cushion rubber and a side rubber of the sidewall portions is 1×10.sup.8 Ω or greater.

A pneumatic tire has a rubber member constructed by a rubber ribbon winding body formed by spirally winding a rubber ribbon. The rubber ribbon includes a composite rubber ribbon which is formed by a non-conductive rubber, and a conductive rubber partly covering the non-conductive rubber. The composite rubber ribbon has a flat cross sectional shape and is gradually reduced in its thickness toward both ends. The conductive rubber has a cross sectional area which is equal to or less than 3% of a cross sectional area of the composite rubber ribbon, and forms a surface in one side and a surface in the other side in both ends of the composite rubber ribbon. The composite rubber ribbons that are adjacent in the width direction are partly overlapped, and a conductive route is provided by the conductive rubber connected between the composite rubber ribbons.

A tire tread includes a silica bar extending in a tire circumferential direction. An upper part of the silica bar is exposed to a cap tread so as to contact the road. The tire tread improves grip performance on wet roads, thereby offering a tire suitable for high-speed driving.

The present invention relates to a tire tread comprising a tread cap comprising at least one tread cap rubber compound, at least three circumferential grooves, wherein at least portions of the sidewalls and the bottom of each of said grooves are formed by a circumferential groove reinforcement, and wherein a first groove reinforcement of a groove laterally next to the equatorial plane of the tire comprises a first reinforcement rubber compound which has a higher hardness than the tread cap rubber compound, and wherein a second groove reinforcement of a groove with a larger lateral distance to the equatorial plane of the tire than the first groove, comprises a second reinforcement rubber compound which has a higher hardness than the tread cap rubber compound and a lower hardness than the second reinforcement rubber compound.

The pneumatic tire includes: a belt layer, a belt reinforcing layer, a tread portion, sidewall portions, a rim cushion rubber, and an electrically conductive rubber disposed in the rim cushion rubber and includes a first end in contact with a rim and exposed on an outer surface of the rim cushion rubber and a second end in contact with a tire component adjacent to the rim cushion rubber. The electrical resistance value of the electrically conductive rubber and a portion of the tread portion is 1×10.sup.6 Ω.Math.cm or less. The electrical resistance value of the tire component, a coating rubber of the belt layer, and a coating rubber of the belt reinforcing layer is from 1×10.sup.6 Ω.Math.cm to 1×10.sup.8 Ω.Math.cm. The electrical resistance value of the rim cushion rubber and a side rubber of the sidewall portions is 1×10.sup.8 Ω.Math.cm or greater.

The invention relates to a tire having a rubber tread of a circumferentially zoned tread. The tread zones are comprised of three circumferential load bearing zones, with each zone containing a portion of the running surface of the tread, comprised of a silica-rich intermedial rubber zone positioned between and extending beneath two carbon black-rich lateral tread zones. The tread configuration contains an underlying carbon black-rich base rubber layer. The intermedial and stratified lateral zones are comprised of rubber compositions having differentiated rebound physical properties. A path of least electrical resistance extends from a lateral carbon black-rich rubber tread zone to the carbon black-rich tread base layer by an extension of a lateral tread zone or by an intermediate carbon black-rich rubber bridge.

A pneumatic tire is provided with an electrically conductive portion at least extending continuously from a bead portion to a belt layer. The electrically conductive portion has a linear structure. The linear structure includes an electrically conductive linear member linearly formed of electrically conductive material with an electrical resistivity of less than 1×10̂8 Ω/cm. The electrically conductive portion ensures an electrically conductive path from the bead portion to the belt layer.

This invention discloses a tire tread comprising: (a) a first tread cap layer comprising a first rubber composition; and (b) a second tread cap layer arranged radially inside of the first tread cap layer comprising a second rubber composition; wherein at 0° C. the rebound resilience of the first rubber composition is within a range of 10% to 25%, the rebound resilience of the second rubber composition is within a range of 15% to 35% and is at least 5% lower than that of the second rubber composition; and wherein at 100° C. the rebound resilience of the first rubber composition is within a range of 45% to 65%, the rebound resilience of the second rubber composition is within a range of 60% to 75% and is at least 3% higher than that of the first rubber composition.

A conductive caster wheel is adapted to be mounted on a cart The conductive caster wheel includes a caster hub adapted to be sleeved on a bearing of the cart, a wheel body sleeved on the caster hub, and a conductive plate disposed inside the caster hub and the wheel body. The conductive plate has an inner conductive section. and an outer conductive section. The inner conductive section is exposed from an inner surrounding surface of the caster hub, and is adapted to be electrically connected. to the bearing. The outer conductive section is electrically connected to the inner conductive section, is exposed from an outer surrounding surface of the wheel body, and is adapted to be in contact with a ground surface.