Tire

Abstract

To continuously reduce electric resistance of a tire.SOLUTION: A tire includes a pair of bead parts 10 where a bead core 11 and a bead part rubber 30 having volume resistivity of less than 1×10^8[Ω cm] are arranged, at least one carcass layer 13 which is bridged between the pair of bead parts 10 and has volume resistivity of 1×10^8[Ω cm] or more, a belt layer 14 which is arranged outside in a tire radial direction of the carcass layer 13, a tread rubber 15 which is arranged outside in the tire radial direction of the belt layer 14, and a conductive member 50 which is formed into a sheet shape and continuously extends to the bead parts 10 from at least a position overlapped with an end 144 in a tire width direction of the belt layer 14 on a tire inner surface 25, and has volume resistivity of less than 1×10^8[Ω cm], wherein the conductive member 50 has an inside end 51 in the tire radial direction covered with the bead part rubber 30 arranged in the bead part 10.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a tire. [Background technology]

[0002] In recent years, there has been an increasing demand for fuel-efficient tires due to environmental issues and the like. As a method for making tires more fuel-efficient, a method is used in which the rolling resistance of tires is reduced by increasing the silica content of the rubber compound constituting the cap tread, under tread, sidewall rubber, etc. of the tire. However, since silica has high insulating properties, when the silica content of the rubber compound used in the cap tread, etc. is increased, the electric resistance value of the cap tread, etc. increases, and the static electricity suppression performance of the tire is reduced. When the static electricity suppression performance of a tire is reduced, static electricity generated during the running of a vehicle is easily accumulated, which is likely to cause radio interference such as radio noise.

[0003] For this reason, some conventional pneumatic tires are equipped with conductive members with low electrical resistance in order to improve the static electricity suppression performance and make it easier to release static electricity generated on a vehicle while the vehicle is running onto the road surface. For example, in Patent Document 1, a conductive portion having a surface resistivity of less than 1×10^8 [Ω·mm^2] is arranged so as to extend continuously from the bead portion to the belt layer while being exposed on the inner circumferential surface of the tire, thereby improving the static electricity suppression performance of the tire. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-107720 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a rubber sheet is used as the conductive member, the adhesiveness of the conductive member to the inner liner may deteriorate. In this case, when the conductive member is attached to the inner liner and exposed to the inner circumferential surface of the tire, there is a risk that the conductive member may peel off from the end portion on the bead side, which is prone to bending during tire transportation and use. When the conductive member peels off from the inner liner, the effect of the conductive member in reducing electrical resistance is reduced, so there is room for improvement in terms of continuously reducing the electrical resistance of the tire.

[0006] The present invention has been made in view of the above, and has an object to provide a tire that can continuously reduce the electrical resistance of the tire. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, a tire according to the present invention comprises a pair of bead portions in which a bead core and a bead portion rubber having a volume resistivity of less than 1×10^8 [Ω·cm] are arranged, at least one carcass layer is bridged between the pair of bead portions and has a volume resistivity of 1×10^8 [Ω·cm] or more, a belt layer is arranged on the tire radial outside of the carcass layer, a tread rubber is arranged on the tire radial outside of the belt layer, and a conductive member formed in a sheet shape and extending continuously from a position on the tire inner surface overlapping at least an end of the belt layer in the tire width direction to the bead portions, and having a volume resistivity of less than 1×10^8 [Ω·cm], wherein an inner end of the conductive member in the tire radial direction is covered by the bead portion rubber arranged in the bead portion.

[0008] In the tire, the conductive member preferably has a thickness T within a range of 0.01 mm≦T≦3.0 mm.

[0009] In addition, in the above tire, it is preferable that the tread rubber has a cap tread that constitutes the tire contact surface, and an undertread that is laminated on the tire radially inward side of the cap tread, and has an earth tread that has a volume resistivity of less than 1 x 10^8 [Ω·cm] and penetrates at least the cap tread to be exposed to the tire contact surface.

[0010] In addition, in the above tire, it is preferable that a relationship between a height H in the tire radial direction from a position of an outer end portion in the tire radial direction of the portion of the conductive member covered by the bead portion rubber to a portion of the conductive member that is located innermost in the tire radial direction and a tire cross-sectional height SH is within a range of 0.10≦H / SH≦0.35.

[0011] In the above tire, it is preferable that the relationship between a thickness TR from the conductive member to the tire inner surface at a position on the inner side of the bead core in the tire width direction and a thickness T of the conductive member is within a range of 1.0≦TR / T≦4.5.

[0012] In the tire, it is preferable that a length L of a portion of the conductive member that is covered by the bead portion rubber in a cross section in the tire meridian direction is within a range of 15 mm≦L≦40 mm.

[0013] In the tire, it is preferable that the conductive member is formed in a band shape and is disposed so that the width direction of the band coincides with the tire circumferential direction.

[0014] In the tire described above, it is preferable that a width W of the conductive member at a tire maximum width position and a tire circumference Lp at the tire maximum width position satisfy a relationship of W / Lp≦0.10.

[0015] In addition, in the above tire, it is preferable that the difference Hs(E)-Hs(C) between the rubber hardness Hs(E) of the conductive member and the rubber hardness Hs(C) of the bead portion rubber is within a range of -5≦Hs(E)-Hs(C)≦5. Effect of the Invention

[0016] The tire according to the present invention has an effect of being able to continuously reduce the electrical resistance of the tire. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment. [Diagram 2] FIG. 2 is a detailed view of a region on one side from the tire equatorial plane in the tire width direction of FIG. [Diagram 3] FIG. 3 is an explanatory diagram of the wrap width of the conductive member relative to the belt layer. [Figure 4] FIG. 4 is a detailed view of part A in FIG. [Diagram 5] FIG. 5 is a detailed view of the conductive member at a position on the inner side of the bead core in the tire width direction in FIG. [Figure 6] FIG. 6 is a schematic diagram showing an arrangement of conductive members when the pneumatic tire is viewed in the direction of the tire rotation axis. [Figure 7] FIG. 7 is an explanatory diagram showing a modified example of the pneumatic tire according to the embodiment, in which the end portion of the conductive member is located on the inner side in the tire radial direction of the bead core. [Figure 8] FIG. 8 is an explanatory diagram showing a modified example of the pneumatic tire according to the embodiment, in which the conductive member wraps around to the outer side of the bead core in the tire width direction. [Figure 9] FIG. 9 is an explanatory diagram showing a modified example of a pneumatic tire according to the embodiment, in which the end portion of the conductive member is embedded in the bead portion rubber. [Figure 10]FIG. 10 is an explanatory diagram showing a modified example of the pneumatic tire according to the embodiment, in which the conductive member is bent at the bead portion. [Figure 11] FIG. 11 is a schematic diagram showing a modified example of a pneumatic tire according to the embodiment, illustrating an arrangement of conductive members when the pneumatic tire is viewed in the direction of the tire rotation axis. [Figure 12] FIG. 12 is an explanatory diagram showing a modified example of a pneumatic tire according to the embodiment, in which a conductive member is disposed across the tire equatorial plane in the tire width direction. [Figure 13] FIG. 13 is an explanatory diagram showing a modified example of a pneumatic tire according to the embodiment, in which a conductive member is disposed across the tire equatorial plane in the tire width direction. [Figure 14] FIG. 14 is an explanatory diagram showing a modified example of a pneumatic tire according to the embodiment, in which conductive members are disposed across both sides in the tire width direction. [Figure 15] FIG. 15 is an explanatory diagram showing a modified example of a pneumatic tire according to the embodiment, in which conductive members are disposed on both sides in the tire width direction. [Figure 16] FIG. 16 is an explanatory diagram showing a modified example of the pneumatic tire according to the embodiment, in which an earth tread is arranged. [Figure 17A] FIG. 17A is a chart showing the results of a performance evaluation test of a pneumatic tire. [Figure 17B] FIG. 17B is a chart showing the results of a performance evaluation test of a pneumatic tire. [Figure 17C] FIG. 17C is a chart showing the results of a performance evaluation test of a pneumatic tire. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of a tire according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that are replaceable and easily conceivable by a person skilled in the art, or those that are substantially the same.

[0019] [Embodiment] [Pneumatic tires] In the following description, a pneumatic tire 1 will be used as an example of a tire according to the present invention. The pneumatic tire 1, which is an example of a tire, can be filled with air, an inert gas such as nitrogen, and other gases.

[0020] In the following description, the tire radial direction refers to a direction perpendicular to the tire rotation axis (not shown) which is the rotation axis of the pneumatic tire 1, the tire radial inner side refers to the side facing the tire rotation axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotation axis as the central axis. The tire width direction refers to a direction parallel to the tire rotation axis, the tire width inner side refers to the side facing the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the tire width outer side refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane perpendicular to the tire rotation axis and passing through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL coincides with a tire width centerline which is the center position of the pneumatic tire 1 in the tire width direction. The tire width is the width in the tire width direction between the portions located outermost in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line refers to a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the pneumatic tire 1. In the following description, the tire meridian section refers to a section obtained by cutting the tire with a plane that includes the tire rotation axis.

[0021] 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire 1 according to an embodiment. The figure shows one side region in the tire radial direction. The figure also shows a radial tire for passenger cars as an example of a pneumatic tire.

[0022] A pneumatic tire 1 according to the embodiment has an annular structure centered on the tire rotation axis, and includes a tread portion 2, a pair of sidewall portions 3, 3, a pair of bead portions 10, 10, a carcass layer 13, a belt layer 14, and a carcass inner rubber layer 20. Of these, the pair of sidewall portions 3, 3 and the pair of bead portions 10, 10 are each disposed on either side of the tire equatorial plane CL in the tire width direction.

[0023] The pair of bead portions 10, 10 are located on the inner side of the pair of sidewall portions 3, 3 in the tire radial direction, and each has a bead core 11, a bead filler 12, and a bead portion rubber 30. That is, the pair of bead cores 11, 11, the pair of bead fillers 12, 12, and the pair of bead portion rubbers 30, 30 are arranged on both sides of the tire equatorial plane CL in the tire width direction.

[0024] The pair of bead cores 11, 11 are annular members formed by bundling a plurality of bead wires, and constitute the cores of the pair of bead portions 10, 10. The pair of bead fillers 12, 12 are disposed on the outer sides of the pair of bead cores 11, 11 in the tire radial direction, respectively, to reinforce the bead portion 10.

[0025] The carcass layer 13 has a single-layer structure consisting of one carcass ply, or a multi-layer structure consisting of multiple carcass plies stacked together, and is toroidally stretched between a pair of bead portions 10, 10 located on both sides in the tire width direction to form the tire framework. The carcass ply of the carcass layer 13 is formed by coating multiple carcass cords made of steel or organic fiber material such as aramid, nylon, polyester, or rayon with coating rubber and rolling them. The carcass ply of the carcass layer 13 has a carcass angle, defined as the inclination angle of the extension direction of the carcass cord with respect to the tire circumferential direction, within the range of 80 degrees to 95 degrees in absolute value.

[0026] In this embodiment, the carcass layer 13 has a single-layer structure and is continuously laid between the bead cores 11, 11 on both sides in the tire width direction. In addition, both ends of the carcass layer 13 are wrapped back and secured to the outside in the tire width direction so as to encase the bead cores 11 and the bead fillers 12. In other words, the carcass layer 13 is wrapped back near both ends in a tire meridian cross section from the inside in the tire width direction of the bead cores 11 and the bead fillers 12 to the inside in the tire radial direction, and then wrapped back to the outside in the tire width direction.

[0027] Therefore, the carcass layer 13 has a carcass body portion 13a arranged between the pair of bead portions 10, and a turn-up portion 13b formed continuously from the carcass body portion 13a and folded back from the inner side in the tire width direction of the bead core 11 to the outer side in the tire width direction. The carcass body portion 13a here is a portion formed between the inner sides in the tire width direction of the pair of bead cores 11 in the carcass layer 13, and the turn-up portion 13b is a portion formed continuously from the carcass body portion 13a on the inner side in the tire width direction of the bead core 11, and folded back through the inner side in the tire radial direction of the bead core 11 to the outer side in the tire width direction. The bead filler 12 is arranged on the inner side in the tire width direction of the turn-up portion 13b, which is the portion folded back to the outer side in the tire width direction of the bead core 11, and on the outer side in the tire radial direction of the bead core 11.

[0028] In the carcass ply of the carcass layer 13 thus formed, the tan δ value of the coating rubber of the carcass cord at 60°C is preferably 0.22 or less. The carcass layer 13 also has a volume resistivity of 1×10^8 [Ω·cm] or more, more specifically, the volume resistivity of the coating rubber of the carcass cord of the carcass layer 13 is 1×10^8 [Ω·cm] or more. This reduces the rolling resistance of the tire. Coating rubber having such a volume resistivity is produced, for example, by using a low heat generating compound with a small amount of carbon. Furthermore, the coating rubber may be constructed without using silica, or may be reinforced by containing silica.

[0029] The tan δ value at 60° C. is measured using a viscoelasticity spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd. under the conditions of an initial strain of 10%, an amplitude of ±0.5%, and a frequency of 20 Hz.

[0030] Volume resistivity (volume specific resistance) is measured based on JIS K6271, "Vulcanized rubber and thermoplastic rubber - Determination of volume resistivity and surface resistivity." In general, if the volume resistivity is less than 1×10^8 [Ω·cm] or the surface resistivity is less than 1×10^8 [Ω / cm], the material can be said to have conductivity that can suppress static electricity buildup.

[0031] A pair of bead portion rubbers 30, 30 of the pair of bead portions 10, 10 are respectively arranged on the tire radially inner side of the bead cores 11, 11 on both sides in the tire width direction and the turnup portion of the carcass layer 13. The bead portion rubber 30 is a portion that comes into contact with the rim flange R of the rim wheel when the pneumatic tire 1 is mounted on the rim wheel, and constitutes the contact surface of the bead portion 10 with respect to the rim flange R.

[0032] The bead portion rubber 30 may be a rim cushion rubber that contacts the rim flange R when the pneumatic tire 1 is fitted to a rim wheel, or a rubber chafer that prevents the carcass layer 13 from contacting the rim flange R and being damaged when the pneumatic tire 1 is fitted to a rim wheel. When the rim cushion rubber and the rubber chafer are arranged adjacent to each other in the bead portion 10, it may be difficult to clearly distinguish the boundary between them. Therefore, in this embodiment, the rim cushion rubber and the rubber chafer arranged in the bead portion 10 are collectively referred to as the bead portion rubber 30. The bead portion rubber 30 has a volume resistivity of less than 1×10^8 [Ω·cm], and the volume resistivity of the bead portion rubber 30 is preferably 1×10^7 [Ω·cm] or less.

[0033] The belt layer 14 has one or more belt plies extending in the tire width direction, and in this embodiment, a plurality of belt plies 141 to 143 are laminated. That is, in this embodiment, the belt layer 14 is configured by laminating a pair of cross belts 141, 142 and a belt cover 143 in the tire radial direction, and is disposed on the tire radial outer side of the carcass layer 13 and wound around the outer periphery of the carcass layer 13. The pair of cross belts 141, 142 are configured by covering a plurality of belt cords made of steel or organic fiber material with coating rubber and rolling them, and the belt angle, which is the inclination angle of the extension direction of the belt cords with respect to the tire circumferential direction, is within the range of 20 [deg] or more and 65 [deg] or less in absolute value. In addition, the pair of cross belts 141, 142 have a so-called cross-ply structure in which the belt angles have mutually opposite signs and are laminated with the extension directions of the belt cords crossing each other. That is, the inclination directions of the belt cords of the pair of cross belts 141, 142 in the tire width direction with respect to the tire circumferential direction are opposite to each other. The belt cover 143 is formed by rolling a plurality of cords made of steel or organic fiber material covered with coated rubber, and the belt angle is within the range of 0 degrees or more and 10 degrees or less in absolute value. The belt cover 143 is also arranged by being layered on the outer side of the cross belts 141, 142 in the tire radial direction.

[0034] The tread portion 2 is configured with a tread rubber 15 which is a rubber composition, and is disposed on the tire radial outer side of the carcass layer 13 and the belt layer 14, and is exposed at the outermost part in the tire radial direction of the pneumatic tire 1. Therefore, the outer peripheral surface of the tread portion 2 constitutes a part of the contour of the pneumatic tire 1, and a plurality of grooves such as circumferential main grooves 6 and lug grooves (not shown) extending in the tire circumferential direction are formed in the tread portion 2. In addition, the tread rubber 15 which constitutes the tread portion 2 has a cap tread 151 and an under tread 152.

[0035] The cap tread 151 is a rubber member located at the outermost side of the tread portion 2 in the tire radial direction and constituting the tire contact surface 2a, and may have a single layer structure (see FIG. 1) or a multi-layer structure (not shown). The tan δ value of the cap tread 151 at 60°C is preferably 0.25 or less. The volume resistivity of the cap tread 151 is preferably in the range of 1×10^8 [Ω·cm] or more, more preferably in the range of 1×10^10 [Ω·cm] or more, and more preferably in the range of 1×10^12 [Ω·cm] or more. This reduces the rolling resistance of the pneumatic tire 1. The cap tread 151 having such a volume resistivity is produced by using a low heat generating compound with a small amount of carbon mixed and reinforcing it by increasing the silica content.

[0036] The undertread 152 is a member laminated on the inner side in the tire radial direction of the cap tread 151. The volume resistivity of the undertread 152 is preferably lower than the volume resistivity of the cap tread 151.

[0037] The pair of sidewall portions 3, 3 are each configured to have a sidewall rubber 16, and the pair of sidewall rubbers 16, 16 of the pair of sidewall portions 3, 3 are each disposed on the outer side of the carcass layer 13 in the tire width direction. The tan δ value of the sidewall rubber 16 at 60[℃] is preferably 0.20 or less. The volume resistivity of the sidewall rubber 16 is preferably in the range of 1×10^8[Ω·cm] or more, more preferably in the range of 1×10^10[Ω·cm] or more, and more preferably in the range of 1×10^12[Ω·cm] or more. As a result, the rolling resistance of the pneumatic tire 1 is reduced. The sidewall rubber 16 having such a volume resistivity is produced by using a low heat generating compound with a small amount of carbon blended and reinforcing it by increasing the silica content.

[0038] Although there are no particular limitations on the upper limit of the volume resistivity of the cap tread 151, the lower limit of the volume resistivity of the undertread 152, the upper limit of the volume resistivity of the sidewall rubber 16, and the lower limit of the volume resistivity of the rim cushion rubber 17, they are subject to physical constraints since they are rubber members.

[0039] The carcass inner rubber layer 20 constitutes a tire inner surface 25 which is the inner surface of the pneumatic tire 1, and faces the tire cavity which is the space inside the pneumatic tire 1. In this way, the carcass inner rubber layer 20 which constitutes the tire inner surface 25 is a rubber layer which is disposed on the tire cavity side with respect to the carcass layer 13, and covers the carcass layer 13 from the tire cavity side.

[0040] [Static charge suppression structure] 2 is a detailed view of a region on one side of the tire equatorial plane CL in the tire width direction in FIG. 1. The pneumatic tire 1 according to this embodiment employs an anti-static structure in order to discharge static electricity generated on the vehicle during vehicle travel to the road surface, and a conductive member 50 is used as the anti-static structure. The conductive member 50 is formed in a sheet shape and extends continuously from a position overlapping at least an end 144 of the belt layer 14 in the tire width direction on the tire inner surface 25 to the bead portion 10 at a part of the tire circumferential direction, and has a volume resistivity of less than 1×10^8 [Ω·cm]. In this embodiment, the conductive member 50 is arranged to overlap the belt layer 14 in the tire radial direction within a predetermined range in the tire width direction.

[0041] At the position of the bead portion 10, the conductive member 50 has an inner end 51 in the tire radial direction covered by the bead portion rubber 30 disposed at the bead portion 10. That is, the conductive member 50 is not exposed to the tire cavity side at the portion of the bead portion 10 on the tire cavity side where the bead portion rubber 30 is disposed because it is covered by the bead portion rubber 30, and at the portion on the tire radial outer side of the bead portion rubber 30, the conductive member 50 is exposed to the tire cavity side and disposed on the tire inner surface 25. That is, the conductive member 50 is disposed continuously from the bead portion 10 to a position on the tire radial inner side of the belt layer 14, and is covered by the bead portion rubber 30 at the portion of the bead portion 10 where the bead portion rubber 30 is disposed, and is disposed on the tire inner surface 25 at the portion on the tire radial outer side of the bead portion rubber 30.

[0042] In this embodiment, the conductive member 50 is disposed continuously from one of the bead portions 10 disposed on both sides of the tire equatorial plane CL in the tire width direction to a position on the inner side in the tire radial direction of the belt layer 14. That is, in this embodiment, the conductive member 50 is disposed on one side of the tire equatorial plane CL in the tire width direction.

[0043] In this embodiment, the bead portion 10 refers to the region from the measurement point of the rim diameter to 1 / 3 of the tire cross-sectional height SH. The tire cross-sectional height SH refers to 1 / 2 of the difference between the tire outer diameter and the rim diameter, and is measured with the pneumatic tire 1 mounted on a specified rim, a specified internal pressure applied, and no load applied.

[0044] Here, the specified rim refers to the "applicable rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO. The specified load refers to the "maximum load capacity" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "load capacity" specified by ETRTO. However, in JATMA, for passenger car tires, the specified internal pressure is 180 kPa, and the specified load is 88% of the maximum load capacity.

[0045] The conductive member 50 is disposed along the carcass inner rubber layer 20. The conductive member 50 is disposed along the carcass inner rubber layer 20 on the surface of the carcass inner rubber layer 20 facing the tire cavity by, for example, using an adhesive.

[0046] In detail, the conductive member 50 is disposed along the tire inner surface 25 on the tire radially inner side of the carcass inner rubber layer 20 at a position on the tire radially inner side of the belt layer 14, and the tire direction outer end of the conductive member 50 is located on the tire radially inner part of the belt layer 14. As a result, the conductive member 50 is disposed overlapping the belt layer 14 in the tire radial direction at a position on the tire radially inner side of the belt layer 14.

[0047] Moreover, at the position of the sidewall portion 3, the conductive member 50 is disposed along the tire inner surface 25 on the inner side in the tire width direction of the carcass inner rubber layer 20. Furthermore, at the outer side in the tire radial direction of the position where the bead portion rubber 30 in the bead portion 10 is disposed, the conductive member 50 is disposed along the tire inner surface 25 on the inner side in the tire width direction of the carcass inner rubber layer 20, and at the position where the bead portion rubber 30 in the bead portion 10 is disposed, the conductive member 50 is disposed to be covered by the bead portion rubber 30.

[0048] That is, in the portion of the bead portion 10 where the bead portion rubber 30 is disposed, the carcass inner side rubber layer 20 is covered with the bead portion rubber 30, and the conductive member 50 is disposed between the carcass inner side rubber layer 20 and the bead portion rubber 30. By disposing the conductive member 50 between the carcass inner side rubber layer 20 and the bead portion rubber 30 in this manner, the conductive member 50 is disposed overlapping the bead portion rubber 30 in the portion of the bead portion 10 where the bead portion rubber 30 is disposed, and is in contact with the bead portion rubber 30. This ensures a conductive path from the rim fitting surface through the bead portion rubber 30 to the conductive member 50, and ensures a conductive path from the position of the bead portion 10 to the position of the belt layer 14.

[0049] The conductive members 50 arranged in this manner extend in a direction close to the tire width direction at the positions where they overlap the belt layer 14 in the tire radial direction, and extend in a direction close to the tire radial direction at the positions of the sidewall portion 3 and the bead portion 10.

[0050] 3 is an explanatory diagram of the lap width La of the conductive member 50 relative to the belt layer 14. The relationship between the width Lbp of the belt layer 14 in the periphery direction and the width of the conductive member 50 in the periphery direction at the portion where the conductive member 50 overlaps with the belt layer 14 in the tire radial direction, i.e., the lap width La of the conductive member 50 relative to the belt layer 14, satisfies 0.01≦La / Lbp≦1. The lap width La of the conductive member 50 relative to the belt layer 14 is preferably La≧3 [mm]. In this case, the lap width La of the conductive member 50 is the distance La in the periphery direction of the portion of the conductive member 50 located on the inner side of the belt layer 14 in the tire radial direction.

[0051] In this embodiment, the periphery direction refers to a direction along the surface of the pneumatic tire 1 at the same position in the tire circumferential direction. In other words, the periphery direction is close to the tire width direction at the position of the tread portion 2, and close to the tire radial direction at the position of the sidewall portion 3.

[0052] In this case, the width Lbp of the belt layer 14 in the periphery direction is the periphery length between the intersection points P of the perpendicular lines Q drawn from the end portions 144 on both sides in the tire width direction of the belt ply having the widest width in the tire width direction toward the tire inner surface 25 and the tire inner surface 25. The lap width La of the conductive member 50 with respect to the belt layer 14 is the length in the periphery direction of the portion of the conductive member 50 located on the inner side in the tire radial direction of the belt layer 14, specifically, the length in the periphery direction of the portion of the conductive member 50 located between the intersection points P.

[0053] FIG. 4 is a detailed view of part A in FIG. 2. The carcass inner rubber layer 20 is formed by laminating an inner liner 21 constituting the tire inner surface 25 and a tie rubber 22 arranged on the side of the inner liner 21 where the carcass layer 13 is located. Among them, the inner liner 21 is an air permeation prevention layer, and by being arranged to cover the carcass layer 13, it suppresses oxidation due to exposure of the carcass layer 13 and also prevents leakage of air filled in the tire. In addition, the inner liner 21 is composed of, for example, a rubber composition mainly composed of butyl rubber, a thermoplastic resin, a thermoplastic elastomer composition in which an elastomer component is blended into a thermoplastic resin, and the like. In particular, when the inner liner 21 is composed of a thermoplastic resin or a thermoplastic elastomer composition, the inner liner 21 can be made thinner than when the inner liner 21 is composed of butyl rubber, so that the tire weight can be significantly reduced.

[0054] In addition, the air permeability coefficient of the inner liner 21 is preferably 100×10^-12 [cc·cm / cm^2·sec·cmHg] or less, and more preferably 50×10^-12 [cc·cm / cm^2·sec·cmHg] or less, when measured in accordance with JIS K7126-1 at a temperature of 30°C. The volume resistivity of the inner liner 21 is preferably in the range of 1×10^8 [Ω·cm] or more, and generally preferably 1×10^9 [Ω·cm] or more.

[0055] Examples of the rubber composition containing butyl rubber as a main component include butyl rubber (IIR), butyl-based rubber, etc. The butyl-based rubber is preferably a halogenated butyl rubber such as chlorinated butyl rubber (Cl-IIR) or brominated butyl rubber (Br-IIR).

[0056] Examples of thermoplastic resins include polyamide resins (e.g., nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6 / 66 copolymer (N6 / 66), nylon 6 / 66 / 610 copolymer (N6 / 66 / 610), nylon MXD6, nylon 6T, nylon 9T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer), polyester, resins (e.g., aromatic polyesters such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), polybutylene terephthalate / tetramethylene glycol copolymer, PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer), polynitrile resins (e.g., polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer), poly(meth)acrylate resins (e.g., polymethyl methacrylate (PMMA), polyethyl methacrylate, ethylene ethyl acrylate copolymer (EEA), ethylene acrylic acid copolymer (EAA), ethylene methyl acrylate resin (EMA)), polyvinyl resins (e.g., vinyl acetate (EVA), polyvinyl alcohol (PVA), vinyl alcohol / ethylene Examples of the resin that can be used include polyvinylidene chloride (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, cellulose resin (e.g., cellulose acetate, cellulose acetate butyrate), fluorine resin (e.g., polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE)), imide resin (e.g., aromatic polyimide (PI)), and the like.

[0057] Examples of elastomers include diene rubbers and hydrogenated products thereof (e.g., NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefin rubbers (e.g., ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM)), butyl rubber (IIR), copolymers of isobutylene and aromatic vinyl or diene monomers, acrylic rubber (ACM), ionomers, halogen-containing rubbers (e.g., Br-IIR, Cl-IIR, brominated isobutylene-paramethylstyrene copolymers (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHC, CHR), chlorosulfur rubber, etc.). Examples of suitable rubbers that can be used include chlorinated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid modified chlorinated polyethylene (M-CM), silicone rubber (e.g., methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (e.g., polysulfide rubber), fluororubber (e.g., vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicone rubber, fluorine-containing phosphazene rubber), thermoplastic elastomer (e.g., styrene-based elastomer, olefin-based elastomer, polyester-based elastomer, urethane-based elastomer, polyamide-based elastomer), and the like.

[0058] Moreover, the tie rubber 22 disposed between the inner liner 21 and the carcass layer 13 is a layer for preventing the carcass cord of the carcass layer 13 from biting into the inner liner 21 when the unvulcanized pneumatic tire 1 is inflated during tire manufacturing. Moreover, the tie rubber 22 contributes to air permeation prevention properties and steering stability on dry road surfaces in the manufactured pneumatic tire 1.

[0059] The carcass inner rubber layer 20, in which the inner liner 21 and the tie rubber 22 are laminated, is disposed along the carcass layer 13 on the tire cavity side of the carcass layer 13. In addition, at the position of the bead portion 10, the carcass inner rubber layer 20 is folded back from the inner side in the tire width direction of the bead core 11 toward the inner side in the tire radial direction of the bead core 11, along the carcass layer 13 that is wound back so as to wrap around the bead core 11, in the tire meridian cross section.

[0060] The bead portion rubber 30 disposed in the bead portion 10 is disposed from the inner side of the bead core 11 in the tire width direction in the bead portion 10, passing through the inner side of the bead core 11 in the tire radial direction, and extending to the outer side of the bead core 11 in the tire width direction. The bead portion rubber 30 has an outer end in the tire radial direction located outside the bead core 11 in the tire radial direction on both the inner side and the outer side of the bead core 11 in the tire width direction. In this embodiment, the outer end 30a in the tire radial direction of the bead portion rubber 30 located inside the bead core 11 in the tire width direction is located within a range in which the bead filler 12 is disposed in the tire radial direction, and the outer end 30b in the tire radial direction of the bead core 11 located outside the bead filler 12 in the tire width direction.

[0061] The bead portion rubber 30 is disposed more inward in the tire width direction than the carcass inner rubber layer 20 at the inner portion of the bead core 11 in the tire width direction, and more inward in the tire radial direction than the carcass inner rubber layer 20 at the inner portion of the bead core 11 in the tire radial direction. Therefore, the bead portion rubber 30 covers the carcass inner rubber layer 20 from the inner side in the tire width direction at the inner portion of the bead core 11 in the tire width direction, and covers the carcass inner rubber layer 20 from the inner side in the tire radial direction at the inner portion of the bead core 11 in the tire radial direction.

[0062] That is, the bead portion rubber 30 arranged from the inner side in the tire width direction of the bead core 11 to the outer side in the tire width direction in the bead portion 10 is arranged to cover the bead core 11, the carcass layer 13, and the bead portion rubber 30 in the bead portion 10. For this reason, in the bead portion 10, the surface of the carcass inner rubber layer 20 on the tire cavity side on the tire radially outer side of the position where the bead portion rubber 30 is arranged becomes the tire inner surface 25, and the surface of the bead portion rubber 30 on the tire cavity side becomes the tire inner surface 25 at the position where the bead portion rubber 30 is arranged.

[0063] The bead portion rubber 30 disposed in the bead portion 10 in this manner forms a bead base 36, which is the inner peripheral surface of the bead portion 10, and a bead toe 35, which is the end portion of the bead base 36 on the inner side in the tire width direction. The bead base 36 is the portion that comes into contact with the rim wheel R when the pneumatic tire 1 is mounted on the rim wheel. The bead portion rubber 30 forms the bead base 36, which is the fitting surface for the rim wheel when the pneumatic tire 1 is mounted on the rim wheel.

[0064] Furthermore, the conductive member 50 arranged along the carcass inner rubber layer 20 is arranged on the tire inner surface 25 at the bead portion 10, radially outward of the bead portion rubber 30, and is exposed to the tire cavity. Meanwhile, at a position in the tire radial direction where the portion of the bead portion rubber 30 that constitutes the tire inner surface 25 is arranged, the conductive member 50, together with the carcass inner rubber layer 20, is located outward in the tire width direction of the portion of the bead portion rubber 30 that constitutes the tire inner surface 25, and is covered by the bead portion rubber 30.

[0065] For this reason, at the position where the portion of the bead portion rubber 30 that constitutes the tire inner surface 25 is disposed, the conductive member 50 is not disposed on the tire inner surface 25 and is disposed without being exposed to the tire cavity. In other words, most of the conductive member 50 disposed on the tire radial outer side of the bead portion 10 is disposed on the tire inner surface 25, and the vicinity of the inner end portion 51 of the conductive member 50 in the tire radial direction is not disposed on the tire inner surface 25 and is covered by the bead portion rubber 30.

[0066] Thus, the conductive member 50 covered by the bead portion rubber 30 in the bead portion 10 has a tire radial height H from the position of the outer end 53 in the tire radial direction of the portion of the conductive member 50 covered by the bead portion rubber 30 to the innermost portion 52 that is the portion of the conductive member 50 located most inward in the tire radial direction, and the tire cross-sectional height SH (see FIG. 2) that falls within the range of 0.10≦H / SH≦0.35. In this case, the height H is a value measured when the pneumatic tire 1 is mounted on a specified rim, with the internal pressure at 0 kPa and the load at 0 kN.

[0067] Furthermore, the length L of the conductive member 50, in a cross section in the tire meridian direction, of the portion covered by the bead portion rubber 30 is within the range of 15 mm≦L≦40 mm. In this case, the length L is the length along the conductive member 50 in the tire meridian cross section. That is, in the tire meridian cross section, the length L in this case is the length along the conductive member 50 from the position of the outer end 53 in the tire radial direction of the portion of the conductive member 50 covered by the bead portion rubber 30 to the inner end 51 in the tire radial direction of the conductive member 50, i.e., the end 51 of the conductive member 50 on the side located at the bead portion 10.

[0068] In this embodiment, an inner end portion 51 of the conductive member 50 on the inner side in the tire radial direction is located within a range in which the bead core 11 is arranged in the tire radial direction. That is, the inner end portion 51 of the conductive member 50 on the inner side in the tire radial direction is located on the inner side in the tire width direction of the bead core 11. Also, in this embodiment, the inner end portion 51 of the conductive member 50 on the inner side in the tire radial direction becomes an innermost portion 52 that is located on the innermost side of the conductive member 50 in the tire radial direction.

[0069] Furthermore, the conductive member 50, the vicinity of the inner end portion 51 on the inner side in the tire radial direction, is covered by the bead portion rubber 30, such that the difference Hs(E)-Hs(C) between the rubber hardness Hs(E) of the conductive member 50 and the rubber hardness Hs(C) of the bead portion rubber 30 is within a range of -5≦Hs(E)-Hs(C)≦5. In more detail, the rubber hardness Hs(E) of the conductive member 50 is within a range of 55 to 80, and the rubber hardness Hs(C) of the bead portion rubber 30 is within a range of 60 to 75, and the difference is within a range of -5≦Hs(E)-Hs(C)≦5.

[0070] The rubber hardness Hs here is measured at a temperature of 20°C in accordance with JIS K 6253. The difference Hs(E)-Hs(C) between the rubber hardness Hs(E) of the conductive member 50 and the rubber hardness Hs(C) of the bead portion rubber 30 is preferably within the range of -1≦Hs(E)-Hs(C)≦4.

[0071] 5 is a detailed view of the conductive member 50 at a position on the inner side of the bead core 11 in the tire width direction in FIG. 4. The conductive member 50 arranged along the carcass inner rubber layer 20 has a thickness T within a range of 0.01 mm≦T≦3.0 mm. The thickness T of the conductive member 50 is preferably within a range of 0.3 mm≦T≦2.0 mm. In addition, the relationship between the thickness TR from the conductive member 50 to the tire inner surface 25 at the position on the inner side of the bead core 11 in the tire width direction and the thickness T of the conductive member 50 is within a range of 1.0≦TR / T≦4.5. The conductive member 50 is covered by the bead portion rubber 30 in the range where the bead core 11 is arranged in the tire radial direction, so that the thickness TR from the conductive member 50 to the tire inner surface 25 in this case is substantially the thickness of the bead portion rubber 30.

[0072] FIG. 6 is a schematic diagram showing the arrangement of the conductive member 50 when the pneumatic tire 1 is viewed in the direction of the tire rotation axis. The conductive member 50 is formed in a substantially strip-like shape having a predetermined width and is arranged at one location in the tire circumferential direction. The conductive member 50 is, for example, a strip-like rubber sheet having a volume resistivity of less than 1×10^8 [Ω·cm], which is arranged on the surface of the carcass inner rubber layer 20 on the tire cavity side by using an adhesive. The conductive member 50 formed in a substantially strip-like shape extends in the periphery direction and is arranged along the carcass inner rubber layer 20 with the width direction of the strip approximately in the tire circumferential direction. Therefore, when the pneumatic tire 1 is viewed in the direction of the tire rotation axis, the strip-like conductive member 50 extends along the tire radial direction.

[0073] In this way, the conductive member 50 is arranged with the width direction of the band oriented in the tire circumferential direction, and the width W of the conductive member 50 at the tire maximum width position WP (see FIG. 2) of the pneumatic tire 1 and the tire circumference Lp at the tire maximum width position WP satisfy the relationship W / Lp≦0.10. The tire maximum width position WP in this case refers to the maximum width position of the tire section width as specified by JATMA. The tire section width is measured under the conditions of mounting the tire on a specified rim, applying a specified internal pressure, and applying a load of 0 kN.

[0074] The width W of the conductive member 50 at the tire maximum width position WP is preferably within a range of 0.004≦W / Lp≦0.10, where Lp is the tire circumference at the tire maximum width position WP. Furthermore, the width W of the conductive member 50 at the tire maximum width position WP is preferably within a range of 5 mm or more and 30 mm or less.

[0075] [Actions and Effects] When a pneumatic tire 1 according to the embodiment is mounted on a vehicle and driven, the pneumatic tire 1 rotates while a portion of the surface of the tread portion 2 of the pneumatic tire 1 that is located lower and faces the road surface comes into contact with the road surface. The tire contact surface 2a, which is the surface of the tread portion 2, of the pneumatic tire 1 sequentially comes into contact with the road surface in this manner, thereby generating frictional force between the pneumatic tire 1 and the road surface. This allows the vehicle to transmit driving force, braking force, and turning force to the road surface by the frictional force between the pneumatic tire 1 and the road surface, and the vehicle can run using these driving force, braking force, and turning force.

[0076] In addition, static electricity may be generated while the vehicle is running, and such static electricity flows from the rim flange R through the bead portion rubber 30 and the conductive member 50 to the belt layer 14, and from the belt layer 14 to the tread rubber 15, and is released to the road surface from the tread rubber 15. This allows static electricity generated on the vehicle to be released to the road surface, suppressing charging of the vehicle due to static electricity.

[0077] That is, the conductive member 50, whose volume resistivity is less than 1×10^8 [Ω·cm], allows electricity to flow relatively easily, and can reduce the tire electrical resistance, which is the electrical resistance of the pneumatic tire 1. As a result, the pneumatic tire 1 in which the conductive member 50 is arranged can allow static electricity generated while the vehicle is traveling to flow from the bead portion rubber 30 side to the belt layer 14 side via the conductive member 50, and can suppress charging of the vehicle due to static electricity.

[0078] Here, when the vehicle is traveling, the tread portion 2, the sidewall portion 3, the bead portion 10, etc. rotate while deforming due to the load generated according to the traveling state of the vehicle. In particular, since the bead portion 10 is a portion where the pneumatic tire 1, which elastically deforms, is mounted on the rim R, which has high rigidity and is difficult to deform, elastic deformation is likely to occur in the portion connected to the sidewall portion 3, that is, bending is likely to occur. In other words, the bead portion 10 is difficult to elastically deform in the vicinity of the portion mounted on the rim R because it is integrated with the rim R, which is difficult to deform, while the portion of the bead portion 10 connected to the sidewall portion 3 is likely to bend due to the elastic deformation of the sidewall portion 3.

[0079] In addition, since the bead portion 10 is the part located at the innermost side in the tire radial direction of the pneumatic tire 1, the bead portion 10 is only connected to the sidewall portion 3 located at the outer side in the tire radial direction of the bead portion 10 with respect to other members. Therefore, when an external force acts on the bead portion 10 in a state where the pneumatic tire 1 is not mounted on the rim R, the bead portion 10 is likely to move, for example, in the tire width direction or tilt with respect to the tire rotation axis due to the external force. When the pneumatic tire 1 is not mounted on the rim R, the bead portion 10 moves in this manner due to an external force on the bead portion 10, so that the bead portion 10 is likely to bend at the part connected to the sidewall portion 3. As a result, for example, when an external member or the like abuts against the bead portion 10 or an external member abuts against the bead portion 10 during transportation of the pneumatic tire 1 not mounted on the rim R, the bead portion 10 may move due to the force from the external member and bend at the part connected to the sidewall portion 3.

[0080] Since the conductive member 50 is disposed continuously from the position where the belt layer 14 is disposed to the position of the bead portion 10, when the bead portion 10 is deflected, the portion of the conductive member 50 located at the bead portion 10 also deflects together with other members located at the bead portion 10. The conductive member 50 is disposed on the tire inner surface 25 of the carcass inner rubber layer 20. However, when the conductive member 50 is disposed on the tire inner surface 25 also at the bead portion 10, for example, there is a risk that an end portion 51 on the inner side in the tire radial direction of the conductive member 50 will peel off from the tire inner surface 25 when the bead portion 10 is deflected.

[0081] In other words, if the conductive member 50 is disposed on the tire inner surface 25 even in the bead portion 10, when bending occurs in the bead portion 10, stress concentration occurs near the end portion 51 of the conductive member 50 on the side located in the bead portion 10, and the conductive member 50 disposed on the tire inner surface 25 becomes prone to peeling off from the end portion 51. If peeling of the conductive member 50 from the tire inner surface 25 begins from the end portion 51 of the conductive member 50 on the side located in the bead portion 10, peeling of the conductive member 50 will be triggered by peeling of the end portion 51 of the conductive member 50, and the range of peeling will easily expand due to bending of the bead portion 10 or the sidewall portion 3.

[0082] In this way, when the conductive member 50 separates from the bead rubber 30 due to the widening of the range of peeling of the conductive member 50, static electricity generated while the vehicle is traveling is less likely to flow from the bead rubber 30 to the conductive member 50. For this reason, even if the conductive member 50 is disposed in the pneumatic tire 1, static electricity generated while the vehicle is traveling is less likely to be released to the road surface, making it more difficult to suppress charging of the vehicle due to static electricity.

[0083] In contrast, in the pneumatic tire 1 according to the present embodiment, the conductive member 50, whose volume resistivity is less than 1×10^8 [Ω·cm], extends continuously from the position where it overlaps with the belt layer 14 on the tire inner surface 25 to the bead portion 10, and the inner end portion 51 in the tire radial direction is covered by the bead portion rubber 30. Therefore, the inner end portion 51 of the conductive member 50 in the tire radial direction is held down by the bead portion rubber 30 that covers the end portion 51 of the conductive member 50, so that the conductive member 50 can be prevented from peeling off from the carcass inner rubber layer 20, which is the member in which the conductive member 50 is disposed. As a result, even if the bead portion 10 is deflected during the running of the vehicle or during the transportation of the pneumatic tire 1, the conductive member 50 can be prevented from peeling off from the carcass inner rubber layer 20, and the conductive path from the position of the bead portion 10 to the position of the belt layer 14 can be continuously secured via the conductive member 50. As a result, the electrical resistance of the pneumatic tire 1 can be continuously reduced.

[0084] In addition, since the thickness T of the conductive member 50 is within the range of 0.01 mm≦T≦3.0 mm, the conductive path from the position of the bead portion 10 to the position of the belt layer 14 can be continuously secured via the conductive member 50. In other words, when the thickness T of the conductive member 50 is T<0.01 mm, the thickness T of the conductive member 50 is too thin, so that the conductive member 50 may be scraped off during transportation of the pneumatic tire 1 or during running of the vehicle, and the conductive member 50 may break. In this case, it may be difficult to secure the conductive path from the position of the bead portion 10 to the position of the belt layer 14 via the conductive member 50. In addition, when the thickness T of the conductive member 50 is T>3.0 mm, the thickness T of the conductive member 50 is too thick, so that the step of the member at the position where the conductive member 50 is arranged tends to be large. In this case, the difference in rigidity between the position where the conductive member 50 is placed and the position adjacent to the conductive member 50 where the conductive member 50 is not placed becomes large, so that stress concentration is likely to occur near the position where the conductive member 50 is placed, and there is a risk that the conductive member 50 will be easily peeled off.

[0085] On the other hand, when the thickness T of the conductive member 50 is within the range of 0.01 mm≦T≦3.0 mm, breakage of the conductive member 50 caused by the thickness T of the conductive member 50 being too thin can be suppressed, and peeling of the conductive member 50 caused by the thickness T of the conductive member 50 being too thick can be suppressed. This makes it possible to continuously secure a conductive path from the position of the bead portion 10 to the position of the belt layer 14 via the conductive member 50. As a result, the electrical resistance of the pneumatic tire 1 can be continuously reduced.

[0086] In addition, the relationship between the tire radial height H of the conductive member 50 from the position of the outer end 53 in the tire radial direction of the portion covered by the bead portion rubber 30 to the innermost portion 52 located on the innermost side in the tire radial direction and the tire cross-sectional height SH is within the range of 0.10≦H / SH≦0.35, so that the bead portion rubber 30 can suppress peeling of the conductive member 50 while suppressing the rubber volume of the bead portion rubber 30 from becoming too large. In other words, when the relationship between the tire radial height H of the conductive member 50 in the portion covered by the bead portion rubber 30 and the tire cross-sectional height SH is H<0.10, the range of the conductive member 50 covered by the bead portion rubber 30 is too small, so that it may be difficult for the bead portion rubber 30 to effectively suppress the conductive member 50. In this case, it may be difficult for the bead portion rubber 30 to effectively suppress peeling of the conductive member 50. Furthermore, when the relationship between the height H of the conductive member 50 in the tire radial direction of the portion covered by the bead portion rubber 30 and the tire cross-sectional height SH is H>0.35, the area of ​​the conductive member 50 covered by the bead portion rubber 30 is too large, and the rubber volume of the bead portion rubber 30 may become too large. In this case, the rolling resistance of the pneumatic tire 1 may deteriorate due to the rubber volume of the bead portion rubber 30 becoming too large.

[0087] In contrast, when the relationship between the height H of the conductive member 50 in the tire radial direction of the portion covered by the bead portion rubber 30 and the tire cross-sectional height SH is within the range of 0.10≦H / SH≦0.35, the conductive member 50 can be appropriately suppressed by the bead portion rubber 30 while preventing the area of ​​the conductive member 50 covered by the bead portion rubber 30 from becoming too large. This makes it possible to prevent the rubber volume of the bead portion rubber 30 from becoming too large while preventing the conductive member 50 from peeling off by the bead portion rubber 30. As a result, the electrical resistance of the pneumatic tire 1 can be continuously reduced while preventing the rolling resistance of the pneumatic tire 1 from deteriorating.

[0088] In addition, the relationship between the thickness TR from the conductive member 50 to the tire inner surface 25 at the position on the inner side of the bead core 11 in the tire width direction and the thickness T of the conductive member 50 is within the range of 1.0≦TR / T≦4.5, so that the bead portion rubber 30 can suppress peeling of the conductive member 50 while suppressing the rubber volume of the bead portion rubber 30 from becoming too large. In other words, when the relationship between the thickness TR from the conductive member 50 to the tire inner surface 25 at the position on the inner side of the bead core 11 in the tire width direction and the thickness T of the conductive member 50 is TR / T<1.0, the thickness of the bead portion rubber 30 is too thin, so that it may be difficult for the bead portion rubber 30 to effectively suppress the conductive member 50. In this case, it may be difficult for the bead portion rubber 30 to effectively suppress peeling of the conductive member 50. Furthermore, when the relationship between the thickness TR from the conductive member 50 to the tire inner surface 25 at the inner position of the bead core 11 in the tire width direction and the thickness T of the conductive member 50 is TR / T>4.5, the thickness of the bead portion rubber 30 is too thick, and the rubber volume of the bead portion rubber 30 may be too large. In this case, the rolling resistance of the pneumatic tire 1 may be deteriorated due to the rubber volume of the bead portion rubber 30 being too large.

[0089] In contrast, when the relationship between the thickness TR from the conductive member 50 to the tire inner surface 25 at the inner position of the bead core 11 in the tire width direction and the thickness T of the conductive member 50 is within the range of 1.0≦TR / T≦4.5, the conductive member 50 can be appropriately suppressed by the bead portion rubber 30 while preventing the thickness of the bead portion rubber 30 from becoming too thick. This makes it possible to prevent the rubber volume of the bead portion rubber 30 from becoming too large while preventing the conductive member 50 from peeling off by the bead portion rubber 30. As a result, the electrical resistance of the pneumatic tire 1 can be continuously reduced while preventing the rolling resistance of the pneumatic tire 1 from deteriorating.

[0090] In addition, the length L of the portion of the conductive member 50 covered by the bead portion rubber 30 in a cross section in the tire meridian direction is within the range of 15 mm≦L≦40 mm, so that the bead portion rubber 30 covering the conductive member 50 can continuously suppress peeling of the conductive member 50. In other words, when the length L of the portion of the conductive member 50 covered by the bead portion rubber 30 is L<15 mm, the length L of the portion of the conductive member 50 covered by the bead portion rubber 30 is too short, so that it may be difficult to effectively suppress the conductive member 50 by the bead portion rubber 30. In this case, it may be difficult to effectively suppress peeling of the conductive member 50 by the bead portion rubber 30. Furthermore, when the length L of the portion of the conductive member 50 covered by the bead rubber 30 is L>40 [mm], the length L of the portion of the conductive member 50 covered by the bead rubber 30 is too long, and there is a risk that the bead rubber 30 covering the conductive member 50 will peel off from the conductive member 50. In this case, it becomes difficult to continuously hold down the conductive member 50 by the bead rubber 30, and there is a risk that it becomes difficult to continuously suppress peeling of the conductive member 50 by the bead rubber 30.

[0091] In contrast, when the length L of the portion of the conductive member 50 covered by the bead portion rubber 30 is within the range of 15 mm≦L≦40 mm, the conductive member 50 can be continuously suppressed by the bead portion rubber 30 covering the conductive member 50. This makes it possible to continuously suppress peeling of the conductive member 50 by the bead portion rubber 30 covering the conductive member 50. As a result, the electrical resistance of the pneumatic tire 1 can be continuously reduced.

[0092] Moreover, since the conductive member 50 is formed in a band-like shape and is disposed such that the width direction of the band is oriented in the tire circumferential direction, the conductive member 50 can be disposed from the position of the bead portion 10 to the position of the belt layer 14 while suppressing an increase in the volume of the conductive member 50. This makes it possible to ensure a conductive path from the position of the bead portion 10 to the position of the belt layer 14 via the conductive member 50 while suppressing a deterioration in the rolling resistance of the pneumatic tire 1 due to the conductive member 50. As a result, the electrical resistance of the pneumatic tire 1 can be continuously reduced while suppressing a deterioration in the rolling resistance of the pneumatic tire 1.

[0093] In addition, since the width W of the conductive member 50 at the tire maximum width position WP and the tire circumference Lp at the tire maximum width position WP have a relationship of W / Lp≦0.10, peeling of the conductive member 50 caused by the width W of the conductive member 50 being too wide can be suppressed. In other words, if the width W of the conductive member 50 at the tire maximum width position WP is W / Lp>0.10 with respect to the tire circumference Lp at the tire maximum width position WP, the width W of the conductive member 50 is too wide, and there is a concern that the rigidity difference between the position where the conductive member 50 is disposed and the position adjacent to the position where the conductive member 50 is disposed is likely to become large. In this case, stress concentration is likely to occur near the position where the conductive member 50 is disposed due to the rigidity difference, and peeling of the conductive member 50 is likely to occur.

[0094] In contrast, when the width W of the conductive member 50 at the tire maximum width position WP is W / Lp≦0.10 with respect to the tire circumference Lp at the tire maximum width position WP, it is possible to prevent the rigidity difference between the position where the conductive member 50 is disposed and the position adjacent to the position where the conductive member 50 is disposed from becoming too large. This makes it possible to prevent stress concentration caused by the rigidity difference in the vicinity of the position where the conductive member 50 is disposed, and to prevent the conductive member 50 from peeling off due to the width W of the conductive member 50 being too wide. As a result, it is possible to continuously secure the conductive path from the position of the bead portion 10 to the position of the belt layer 14 via the conductive member 50, and it is possible to continuously reduce the electrical resistance of the pneumatic tire 1.

[0095] In addition, since the difference between the rubber hardness Hs(E) of the conductive member 50 and the rubber hardness Hs(C) of the bead portion rubber 30 is within the range of -5≦Hs(E)-Hs(C)≦5, peeling between the conductive member 50 and the bead portion rubber 30 can be suppressed. In other words, if the difference between the rubber hardness Hs(E) of the conductive member 50 and the rubber hardness Hs(C) of the bead portion rubber 30 is Hs(E)-Hs(C)<-5 or Hs(E)-Hs(C)>5, there is a risk that the difference in rubber hardness Hs between the conductive member 50 and the bead portion rubber 30 becomes too large. In this case, the magnitude of elastic deformation when an external force is applied is significantly different between the conductive member 50 and the bead portion rubber 30, which may cause peeling between the conductive member 50 and the bead portion rubber 30, and may make it difficult to secure a conductive path via the conductive member 50.

[0096] In contrast, when the difference between the rubber hardness Hs(E) of the conductive member 50 and the rubber hardness Hs(C) of the bead portion rubber 30 is within the range of -5≦Hs(E)-Hs(C)≦5, it is possible to prevent the difference in rubber hardness Hs between the conductive member 50 and the bead portion rubber 30 from becoming too large. This makes it possible to prevent separation between the conductive member 50 and the bead portion rubber 30, and to ensure a conductive path from the position of the bead portion 10 to the position of the belt layer 14 via the conductive member 50. As a result, the electrical resistance of the pneumatic tire 1 can be continuously reduced.

[0097] [Variations] In the above-described embodiment, the inner end 51 of the conductive member 50 in the tire radial direction is located on the inner side of the bead core 11 in the tire width direction, but the end 51 of the conductive member 50 may be located other than on the inner side of the bead core 11 in the tire width direction.

[0098] FIG. 7 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram showing a state in which an end 51 of the conductive member 50 is located on the inner side in the tire radial direction of the bead core 11. FIG. 8 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram showing a state in which the conductive member 50 wraps around the outer side in the tire width direction of the bead core 11. FIG. 9 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram showing a state in which the end 51 of the conductive member 50 enters the bead portion rubber 30. For example, as shown in FIG. 7, the conductive member 50 may wrap around from the inner side in the tire width direction of the bead core 11 to the inner side in the tire radial direction of the bead core 11 in the bead portion 10, and the inner end 51 in the tire radial direction of the conductive member 50 may be located on the inner side in the tire radial direction of the bead core 11.

[0099] In addition, the conductive member 50 may be arranged, for example, as shown in FIG. 8, in the bead portion 10, wrapping around from the inner side of the bead core 11 in the tire width direction to the inner side of the bead core 11 in the tire radial direction, and then wrapping around to the outer side of the bead core 11 in the tire width direction.

[0100] In addition, the conductive member 50 may extend from a position on the inner side in the tire width direction of the bead core 11 in the bead portion 10 to the inner side in the tire radial direction, and an inner end portion 51 in the tire radial direction of the conductive member 50 may penetrate into the bead portion rubber 30, for example, as shown in FIG.

[0101] Regardless of the arrangement form of the conductive member 50 in the bead portion 10, the arrangement form is not important so long as the relationship between the tire radial height H from the position of the tire radially outer end 53 of the portion of the conductive member 50 covered by the bead portion rubber 30 to the innermost portion 52 of the conductive member 50 and the tire cross-sectional height SH (see Figure 2) is within the range of 0.10≦H / SH≦0.35, and the length L of the portion covered by the bead portion rubber 30 in the tire meridian cross section is within the range of 15 [mm]≦L≦40 [mm].

[0102] In addition, in the above-described embodiment, the conductive member 50 is arranged along the carcass inner rubber layer 20 from the position of the belt layer 14 to the position of the bead portion 10, and is also arranged along the carcass inner rubber layer 20 at the bead portion 10, but may have a portion that does not run along the carcass inner rubber layer 20.

[0103] FIG. 10 is an explanatory diagram showing a modified example of the pneumatic tire 1 according to the embodiment, and showing a state in which the conductive member 50 is bent at the bead portion 10. For example, as shown in FIG. 10, the conductive member 50 may be bent at the position of the bead portion 10. That is, the conductive member 50 may be arranged in a tire meridian cross section such that the conductive member 50 extending from the outer side of the bead portion 10 in the tire radial direction toward the inner side in the tire radial direction toward the bead portion 10 is bent at the bead portion 10 and extends from the bent position toward the outer side in the tire radial direction. In this case, the bent portion of the conductive member 50 is located on the inner side in the tire radial direction than the inner end portion 51 in the tire radial direction, and the bent portion is formed as the innermost portion 52 of the conductive member 50.

[0104] Even when the conductive member 50 is thus bent at the bead portion 10, it is sufficient that the conductive member 50 is arranged covered by the bead portion rubber 30 from the inner side in the tire width direction. Regardless of whether the conductive member 50 is bent or not, the inner end portion 51 of the conductive member 50 in the tire radial direction is covered by the bead portion rubber 30 arranged at the bead portion 10, thereby making it possible to suppress peeling of the conductive member 50 from the carcass inner rubber layer 20 on which the conductive member 50 is arranged. This makes it possible to continuously ensure a conductive path from the position of the bead portion 10 to the position of the belt layer 14 via the conductive member 50, and makes it possible to continuously reduce the electrical resistance of the pneumatic tire 1.

[0105] Furthermore, in the above-described embodiment, the conductive member 50 is disposed at one location in the tire circumferential direction, but the conductive member 50 may be disposed at multiple locations in the tire circumferential direction. Fig. 11 is a schematic diagram showing a modified example of the pneumatic tire 1 according to the embodiment, and showing the arrangement of the conductive members 50 when the pneumatic tire 1 is viewed in the direction of the tire rotation axis. For example, as shown in Fig. 11, the conductive members 50 may be disposed at regular intervals in the tire circumferential direction. In other words, the conductive members 50 may be disposed radially at predetermined intervals in the tire circumferential direction.

[0106] By arranging a plurality of conductive members 50 along the carcass inner rubber layer 20, the electrical resistance of the pneumatic tire 1 can be effectively reduced by the plurality of conductive members 50. In addition, by arranging a plurality of conductive members 50 radially at regular intervals, it is possible to suppress deterioration of uniformity caused by high rigidity at some positions in the tire circumferential direction. This makes it possible to suppress deterioration of uniformity while reducing the electrical resistance of the pneumatic tire 1.

[0107] In the above-described embodiment, the conductive member 50 is disposed without straddling the tire equatorial plane CL in the tire width direction, but the conductive member 50 may be disposed straddling the tire equatorial plane CL in the tire width direction. FIGS. 12 and 13 are explanatory diagrams showing a modified example of the pneumatic tire 1 according to the embodiment, in which the conductive member 50 is disposed straddling the tire equatorial plane CL in the tire width direction. For example, as shown in FIGS. 12 and 13, the conductive member 50 may be disposed straddling the tire equatorial plane CL in the tire width direction. In this case, the outer end of the conductive member 50 in the tire radial direction may be located on the inner side of the belt layer 14 in the tire radial direction, as shown in FIG. 12. Alternatively, the conductive member 50 disposed straddling the tire equatorial plane CL in the tire width direction may extend beyond the range in which the belt layer 14 is disposed in the tire width direction to the sidewall portion 3 opposite to the sidewall portion 3 on the side on which the conductive member 50 is disposed, as shown in FIG. 13.

[0108] In the above-described embodiment, the conductive member 50 is disposed on one side of the tire equatorial plane CL in the tire width direction, but the conductive member 50 may be disposed on both sides of the tire equatorial plane CL in the tire width direction. FIG. 14 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram showing a state in which the conductive member 50 is disposed on both sides in the tire width direction. For example, as shown in FIG. 14, the conductive member 50 may be disposed on both sides in the tire width direction. That is, the conductive member 50 may be continuously disposed from one bead portion 10 side to the other bead portion 10 side of the bead portions 10 located on both sides in the tire width direction.

[0109] Fig. 15 is an explanatory diagram showing a modified example of the pneumatic tire 1 according to the embodiment, in which the conductive members 50 are arranged on both sides in the tire width direction. As shown in Fig. 15, the conductive members 50 may be arranged in regions on both sides of the tire equatorial plane CL in the tire width direction, with the conductive members 50 being independent of each other and extending from the position of the bead portion 10 to the position of the belt layer 14. In this case, the lap width La of the conductive members 50 with respect to the belt layer 14 (see Fig. 3) may be the same size for the conductive members 50 arranged on both sides in the tire width direction, or may be different sizes.

[0110] In the above-described embodiment, the conductive member 50 is used as a charge suppression structure for discharging static electricity generated in the vehicle during vehicle travel to the road surface, but the charge suppression structure may also use other members than the conductive member 50. FIG. 16 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram showing a state in which an earth tread 60 is arranged. For example, as shown in FIG. 16, an earth tread 60 may be used as a charge suppression structure for discharging static electricity generated in the vehicle to the road surface. In this case, the earth tread 60 is a conductive rubber embedded in the tread rubber 15 and exposed to the tire ground contact surface. In the charge suppression structure having the conductive member 50 and the earth tread 60, static electricity from the vehicle that is caused to flow to the belt layer 14 by the conductive member 50 is discharged from the belt layer 14 to the road surface via the earth tread 60, thereby suppressing charging of the vehicle.

[0111] Specifically, the earth tread 60 is exposed on the tread surface of the tread rubber 15, and penetrates the cap tread 151 and the undertread 152 to be in conductive contact with the belt layer 14. That is, the earth tread 60 penetrates at least the cap tread 151 to be exposed to the tire contact surface 2a. In the modified example shown in Fig. 16, the earth tread 60 penetrates the cap tread 151 and the undertread 152, and the inner end in the tire radial direction is in conductive contact with the belt cover 143. This ensures a conductive path from the belt layer 14 to the road surface.

[0112] The earth tread 60 has an annular structure extending around the entire circumference of the tire, and extends continuously in the tire circumferential direction with a part of it exposed to the tread surface. Therefore, when the pneumatic tire 1 rolls, the earth tread 60 is always in contact with the road surface, and a conductive path from the belt layer 14 to the road surface is always ensured. In the modification shown in Fig. 16, the width of the earth tread 60 in the tire width direction is narrower than the groove width of the circumferential main groove 6 formed in the tread portion 2 and extending in the tire circumferential direction, and is formed between the circumferential main grooves 6 adjacent in the tire width direction.

[0113] Moreover, the earth tread 60 is made of a conductive rubber material having a lower volume resistivity than the tread rubber 15. Specifically, the volume resistivity of the earth tread 60 is preferably less than 1×10^8 [Ω·cm], and more preferably 1×10^6 [Ω·cm] or less.

[0114] As described above, by forming a static electricity suppression structure using the earth tread 60 in addition to the conductive member 50, the path from the rim R through the bead rubber 30, the conductive member 50, and the belt layer 14 to the earth tread 60 can be used as a conductive path for discharging static electricity from the vehicle to the road surface. In other words, the earth tread 60 has a volume resistivity of less than 1×10^8 [Ω·cm] and is exposed to the tire ground contact surface 2a by penetrating at least the cap tread 151, so that the conductive path from the belt layer 14 side to the road surface can be secured by the earth tread 60. As a result, the conductive path from the conductive member 50 to the road surface can be secured, and the conductive path from the rim R to the earth tread 60 can be secured more reliably. Therefore, the electrical resistance between the rim R and the road surface can be more reliably reduced, and the static electricity generated in the vehicle can be more reliably discharged to the road surface. As a result, the electrical resistance of the pneumatic tire 1 can be more reliably reduced.

[0115] Furthermore, by providing the earth tread 60, it is possible to suppress the decrease in static electricity suppression performance when the silica content of the rubber compound constituting the cap tread 151, under tread 152, sidewall rubber 16, etc. is increased in order to reduce the rolling resistance of the pneumatic tire 1 and improve fuel efficiency. In other words, since silica has high insulating properties, when the silica content of the cap tread 151 increases, the volume resistance value of the cap tread 151 increases and the static electricity suppression performance decreases, but by providing the earth tread 60, it is possible to ensure a conductive path between the belt layer 14 and the road surface. As a result, it is possible to reduce the rolling resistance and the electrical resistance of the pneumatic tire 1.

[0116] The above-described embodiments and modified examples may be combined as appropriate. In the above-described embodiments, the pneumatic tire 1 has been used as an example of the tire according to the present invention, but the tire according to the present invention may be something other than the pneumatic tire 1. The tire according to the present invention may be, for example, a so-called airless tire that can be used without filling with gas.

[0117] [Example] 17A to 17C are tables showing the results of performance evaluation tests of pneumatic tires. Below, a description will be given of performance evaluation tests conducted on the above-mentioned pneumatic tire 1 for a conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and a comparative pneumatic tire for comparison with the pneumatic tire 1 according to the present invention. The performance evaluation tests were conducted on the electrical resistance of the pneumatic tire, the peeling resistance of the conductive member, and the rolling resistance of the pneumatic tire.

[0118] The performance evaluation test was conducted using a pneumatic tire with a nominal tire size of 195 / 65R15 91H as the test tire, as specified by JATMA. The evaluation test for the electrical resistance of the pneumatic tire was conducted based on the measurement conditions specified by JATMA, and the electrical resistance [Ω] of the test tire was measured using an R8340A Ultra High Resistance Meter manufactured by Advantest Corporation.

[0119] The evaluation test for the peel resistance of the conductive member was performed by performing an indoor drum test on the test tire using a drum tester with a drum diameter of 1707 mm, running the test tire at a speed of 170 to 210 km / h, a load of 4.82 kN, and an air pressure of 280 kPa at the start of the test for 10 minutes at every 10 km / h, and observing the peeling of the conductive member near the inner end in the tire radial direction. The evaluation of the peel resistance of the conductive member was performed by observing the peeling of the conductive member near the inner end in the tire radial direction after the test, and using an index evaluation of the reciprocal of the length of the peeling of the conductive member, with the conventional example described below being 100. The peel resistance of the conductive member is less likely to occur as the index evaluation value is higher, indicating that the peeling resistance of the conductive member is excellent. Note that if the index is 90 or higher, the peel resistance of the conductive member is maintained at the same level as the conventional example, and the peel resistance of the conductive member is ensured.

[0120] In addition, the evaluation test of the rolling resistance of the pneumatic tire was performed by performing an indoor drum test on the test tire using a drum testing machine with a drum diameter of 1707 [mm], and measuring the rolling resistance of the test tire under the conditions of a load of 4.82 [kN] and a speed of 80 [km / h]. The rolling resistance of the pneumatic tire was evaluated by indexing the reciprocal of the measured rolling resistance, with the conventional example described below being 100. The rolling resistance of the pneumatic tire indicates that the larger the index evaluation value, the lower the rolling resistance and the better the performance in terms of rolling resistance. Note that if the index is 90 or more, the rolling resistance is maintained at the same level as the conventional example, and the performance in terms of rolling resistance is ensured.

[0121] The performance evaluation test was carried out on 19 types of pneumatic tires, including a conventional pneumatic tire which is an example of a conventional pneumatic tire, Examples 1 to 17 which are pneumatic tire 1 according to the present invention, and a comparative example which is a pneumatic tire compared with pneumatic tire 1 according to the present invention. Of these, the comparative example pneumatic tire does not have a conductive member disposed on the surface of the carcass inner rubber layer. Also, while the conventional example pneumatic tire has a conductive member disposed on the surface of the carcass inner rubber layer, the inner end of the conductive member in the tire radial direction is not covered by the bead portion rubber and is exposed to the tire inner surface.

[0122] In contrast, in all of Examples 1 to 17, which are examples of the pneumatic tire 1 according to the present invention, the end 51 of the conductive member 50 on the inner side in the tire radial direction is covered by the bead portion rubber 30. Furthermore, the pneumatic tires 1 according to Examples 1 to 17 are different in the thickness T [mm] of the conductive member 50, the ratio ≦H / SH of the height H in the tire radial direction of the portion of the conductive member 50 covered by the bead portion rubber 30 to the tire cross-sectional height SH, the ratio TR / T of the thickness TR from the conductive member 50 to the tire inner surface 25 to the thickness T of the conductive member 50, the length L [mm] of the portion of the conductive member 50 covered by the bead portion rubber 30, the ratio W / Lp of the width W of the conductive member 50 at the tire maximum width position WP to the tire circumference Lp, and the difference Hs(E)-Hs(C) between the rubber hardness Hs(E) of the conductive member 50 and the rubber hardness Hs(C) of the bead portion rubber 30.

[0123] As a result of carrying out evaluation tests using these pneumatic tires 1, as shown in Figs. 17A to 17C, it was found that the pneumatic tires 1 according to Examples 1 to 17 can reduce the electrical resistance compared to the comparative example, and can improve the peel resistance of the conductive member 50 compared to the conventional example, or can reduce the electrical resistance compared to the conventional example while the peel resistance of the conductive member 50 is about the same as that of the conventional example. This shows that the pneumatic tires 1 according to Examples 1 to 17 can improve the peel resistance of the conductive member 50 compared to the conventional example, or can reduce the electrical resistance compared to the conventional example while the peel resistance of the conductive member 50 is about the same as that of the conventional example, thereby reducing the electrical resistance over a long period of time. In other words, the pneumatic tires 1 according to Examples 1 to 17 can continuously reduce the electrical resistance of the pneumatic tire 1.

[0124] The present disclosure includes the following inventions. Invention[1] a pair of bead portions each including a bead core and a bead portion rubber having a volume resistivity of less than 1×10^8 [Ω·cm]; At least one carcass layer is disposed between the pair of bead portions and has a volume resistivity of 1×10^8 [Ω·cm] or more; A belt layer disposed on the outer side of the carcass layer in the tire radial direction; A tread rubber disposed on the outer side of the belt layer in the tire radial direction; a conductive member formed in a sheet shape and extending continuously from a position on the inner surface of the tire that overlaps at least an end of the belt layer in the tire width direction to the bead portion, and having a volume resistivity of less than 1×10^8 [Ω·cm]; Equipped with The tire is characterized in that an inner end portion of the conductive member in a tire radial direction is covered by the bead portion rubber arranged in the bead portion. Invention[2] The tire according to the invention [1], wherein the conductive member has a thickness T in the range of 0.01 [mm]≦T≦3.0 [mm]. Invention[3] The tread rubber has a cap tread that constitutes a tire contact surface and an undertread that is laminated on the tire radial direction inner side of the cap tread, and A tire according to invention [1] or invention [2], having a volume resistivity of less than 1×10^8 [Ω·cm] and comprising an earth tread penetrating at least the cap tread and exposed to the tire contact surface. Invention[4] The tire according to any one of inventions [1] to [3], wherein the relationship between a height H in the tire radial direction from the position of an outer end portion in the tire radial direction of the portion of the conductive member covered by the bead portion rubber to a portion of the conductive member that is located innermost in the tire radial direction and a tire cross-sectional height SH is within a range of 0.10≦H / SH≦0.35. Invention[5] The tire according to any one of Inventions [1] to [4], wherein the relationship between a thickness TR from the conductive member to the tire inner surface at a position on the inner side of the bead core in the tire width direction and a thickness T of the conductive member is within a range of 1.0≦TR / T≦4.5. Inventions[6] The tire according to any one of Inventions [1] to [5], wherein the length L of the portion of the conductive member that is covered by the bead portion rubber in a cross section in the tire meridian direction is within the range of 15 mm≦L≦40 mm. Inventions[7] A tire according to any one of inventions [1] to [6], wherein the conductive member is formed in a band-like shape and is arranged such that the width direction of the band is oriented in the tire circumferential direction. Inventions[8] The tire according to invention [7], wherein the conductive member has a width W of the conductive member at the tire maximum width position and a tire circumference Lp at the tire maximum width position such that W / Lp≦0.10. Inventions[9] The tire according to any one of inventions [1] to [8], wherein the difference Hs(E)-Hs(C) between the rubber hardness Hs(E) of the conductive member and the rubber hardness Hs(C) of the bead portion rubber is within the range of -5≦Hs(E)-Hs(C)≦5. [Explanation of symbols]

[0125] 1. Pneumatic tires 2 Tread section 3 Sidewall 6 Circumferential main groove 10 Bead section 11 Bead core 12 Bead filler 13 Carcass layer 14 Belt layer 15 Tread rubber 16 Sidewall rubber 20 Carcass inner rubber layer 21 Inner Liner 22 Thai Rubber 25 Tire inner surface 30 Bead rubber 35 Bead Toe 36 Bead base 50 Conductive material 60 Earth Red

Claims

1. a pair of bead portions each including a bead core and a bead portion rubber having a volume resistivity of less than 1×10^8 [Ω cm]; At least one carcass layer is disposed between the pair of bead portions and has a volume resistivity of 1×10^8 [Ω cm] or more; A belt layer disposed on the outer side of the carcass layer in the tire radial direction; A tread rubber disposed on the outer side of the belt layer in the tire radial direction; a conductive member formed in a sheet shape and extending continuously from a position on the inner surface of the tire overlapping at least an end of the belt layer in the tire width direction to the bead portion, and having a volume resistivity of less than 1×10^8 [Ω cm]; Equipped with The tire is characterized in that an inner end portion of the conductive member in a tire radial direction is covered by the bead portion rubber arranged in the bead portion.

2. The tire according to claim 1 , wherein the conductive member has a thickness T within a range of 0.01 mm≦T≦3.0 mm.

3. The tread rubber has a cap tread that constitutes a tire contact surface and an undertread that is laminated on the tire radial direction inner side of the cap tread, and 3. The tire according to claim 1, further comprising an earth tread having a volume resistivity of less than 1×10^8 [Ω·cm] and penetrating at least the cap tread and exposed to the tire contact surface.

4. 3. The tire according to claim 1, wherein a relationship between a height H in the tire radial direction from a position of an outer end portion in the tire radial direction of a portion of the conductive member covered by the bead portion rubber to a portion of the conductive member that is located innermost in the tire radial direction and a tire cross-sectional height SH is within a range of 0.10≦H / SH≦0.

35.

5. 3. The tire according to claim 1, wherein a relationship between a thickness TR from the conductive member to the tire inner surface at a position on an inner side of the bead core in the tire width direction and a thickness T of the conductive member is within a range of 1.0≦TR / T≦4.

5.

6. 3. The tire according to claim 1, wherein a length L of a portion of the conductive member that is covered by the bead portion rubber in a cross section taken along a tire meridian direction is within a range of 15 mm≦L≦40 mm.

7. The tire according to claim 1 or 2, wherein the conductive member is formed in a band shape and is disposed such that a width direction of the band coincides with a tire circumferential direction.

8. The tire according to claim 7 , wherein a width W of the conductive member at a maximum width position of the tire and a tire circumference Lp at the maximum width position of the tire satisfy a relationship of W / Lp≦0.

10.

9. 3. The tire according to claim 1, wherein a difference Hs(E)-Hs(C) between a rubber hardness Hs(E) of the conductive member and a rubber hardness Hs(C) of the bead portion rubber is within a range of -5≦Hs(E)-Hs(C)≦5.

Images