Heavy-duty tires

Abstract

To provide a heavy duty tire 2 that can suppress occurrence of damage due to the presence of an RFID tag 54.SOLUTION: The tire 2 includes a pair of chafers 8 and a tag member 26. The chafer 8 comes into contact with a rim R. The tag member 26 includes the RFID tag 54. The rim R is a normal rim, and a state where the tire 2 is fitted on the rim R and an internal pressure of the tire 2 is adjusted to a normal internal pressure is a normal state. A state where a load equal to 50% of a normal load is applied to the tire 2 in the normal state and the tire 2 is brought into contact with a flat surface FS is a standard ground-contact state. In the standard ground-contact state, the RFID tag 54 is located between an axially outer end PRa of the rim R and a maximum width position PWs of the tire 2 in an axial direction, and is located between a radially outer end PRr of the rim R and the maximum width position PWs of the tire 2 in a radial direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a tire for heavy loads.

Background Art

[0002] In order to manage data such as tire production management, customer information, and driving history, it has been proposed to incorporate an RFID (Radio Frequency Identification) tag into a tire. Various studies have been conducted on the technology of incorporating an RFID tag into a tire (for example, Patent Document 1 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a tire, deformation and restoration are repeated. In a tire in a driving state, the movement at the end portion of the tread and near the maximum width position is active. From the viewpoint of preventing damage to the RFID tag itself, the RFID tag is arranged at a portion where the movement is small. In the case of a tire for heavy loads, since the bead portion has a large rigidity, it is considered to arrange the RFID tag at this bead portion.

[0005] For a tire, the RFID tag is a foreign object. Therefore, from the viewpoints of preventing damage to the RFID tag itself and forming a good communication environment, even if the position of the RFID tag is determined, there is no denying the possibility that distortion increases and damage occurs due to the presence of the RFID tag.

[0006] Just because a tire is designed for heavy loads doesn't mean it's always used under conditions where it's subjected to a load close to its normal load. Sometimes, tires are used under conditions where the load is about 50% of the normal load (light load). If the location where the RFID tag is placed is sensitive to the load, the strain will increase even under light load conditions.

[0007] Heavy-duty tires are used in a wide load range, from light to heavy loads. To ensure that the presence of RFID tags does not reduce the durability of the tires, it is important to check for any increase in distortion caused by the placement of RFID tags, even under light loads.

[0008] This invention has been made in view of these circumstances. The object of this invention is to provide a heavy-duty tire that can suppress the occurrence of damage caused by the presence of RFID tags. [Means for solving the problem]

[0009] The heavy-duty tire according to the present invention comprises a pair of beads, a carcass spanning between the pair of beads, a pair of sidewalls located axially outward of the carcass, a pair of chafers located radially inward of the sidewalls and in contact with the rim, and a tag member including an RFID tag. The bead comprises a core and an apex located radially outward of the core. The carcass comprises a carcass ply. The carcass ply comprises a ply body spanning between the pair of beads and a pair of folded portions connected to the ply body and folded back by the bead. The normal state is when the rim is a normal rim, the tire is mounted on the rim, and the internal pressure of the tire is adjusted to the normal internal pressure. The standard contact state is when the tire in the normal state is subjected to a load of 50% of the normal load and the tire is in contact with a flat surface. In the standard grounding state, the RFID tag is located in the axial direction between the axial outer end of the rim and the maximum width position of the tire, and in the radial direction between the radial outer end of the rim and the maximum width position of the tire. [Effects of the Invention]

[0010] According to the present invention, a heavy-duty tire can be obtained that can suppress the occurrence of damage caused by the presence of RFID tags. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing a part of a heavy-duty tire according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a portion of the tire in Figure 1. [Figure 3] This is a plan view of the tag component. [Figure 4] This is a cross-sectional view along line IV-IV in Figure 3. [Figure 5] This is a cross-sectional view showing a portion of a tire in contact with the ground. [Figure 6] This is a cross-sectional view showing a portion of a tire in contact with the ground. [Figure 7] This is a cross-sectional view showing the outline of the carcass. [Figure 8] This is a cross-sectional view illustrating the identification of the carcass contour. [Figure 9] This is a cross-sectional view illustrating the identification of the contour of another carcass. [Modes for carrying out the invention]

[0012] The present invention will now be described in detail, with reference to drawings as appropriate, based on preferred embodiments.

[0013] The tire of this invention is mounted on a rim. Air is filled inside the tire, and the internal pressure of the tire is regulated. A tire mounted on a rim is also called a tire-rim assembly. A tire-rim assembly comprises a rim and a tire mounted on this rim.

[0014] In this invention, the state in which a tire is mounted on a standard rim, the internal pressure of the tire is adjusted to the standard internal pressure, and no load is applied to the tire is referred to as the standard state.

[0015] In the present invention, unless otherwise specified, the dimensions and angles of each part of the tire are measured in the normal state. The dimensions and angles of each part in the meridian cross-section of the tire that cannot be measured in the state of mounting the tire on the normal rim are measured in the cross-section of the tire obtained by cutting the tire along the plane including the rotation axis. In this measurement, the tire is set so that the distance between the left and right beads coincides with the distance between the beads in the tire mounted on the normal rim.

[0016] The normal rim means the rim defined in the standard on which the tire depends. The "standard rim" in the JATMA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are the normal rims.

[0017] The normal internal pressure means the internal pressure defined in the standard on which the tire depends. The "maximum air pressure" in the JATMA standard, the "maximum value" published in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are the normal internal pressures.

[0018] The normal load means the load defined in the standard on which the tire depends. The "maximum load capacity" in the JATMA standard, the "maximum value" published in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are the normal loads.

[0019] In the present invention, the tread part of the tire is the part of the tire that contacts the road surface. The bead part is the part of the tire that is fitted to the rim. The sidewall part is the part of the tire that bridges between the tread part and the bead part. The tire includes, as parts, a tread part, a pair of bead parts, and a pair of sidewall parts.

[0020] In this invention, the complex modulus of the cross-linked rubber element among the components constituting the tire is measured in accordance with the provisions of JIS K6394. The measurement conditions are as follows: Initial distortion = 10% Dynamic strain = ±1% Frequency = 10Hz Mode = Extension Mode Temperature=70℃ In this measurement, the test specimen (40 mm long x 4 mm wide x 1 mm thick) is sampled from the tire. The length of the test specimen is aligned with the circumferential direction of the tire. If it is not possible to sample a test specimen from the tire, a test specimen is sampled from a sheet of cross-linked rubber (hereinafter also referred to as a rubber sheet) obtained by pressurizing and heating the rubber composition used to form the element to be measured at a temperature of 170°C for 12 minutes. In this invention, the complex modulus of elasticity is expressed as the loss tangent at 70°C.

[0021] [Summary of Embodiments of the Invention] [Configuration 1] A heavy-duty tire according to one aspect of the present invention comprises a pair of beads, a carcass spanning between the pair of beads, a pair of sidewalls located axially outward of the carcass, a pair of chafers located radially inward of the sidewalls and in contact with the rim, and a tag member including an RFID tag, wherein the bead comprises a core and an apex located radially outward of the core, the carcass comprises a carcass ply, the carcass ply comprises a ply body spanning between the pair of beads, and the bead connected to the ply body The rim comprises a pair of folded portions that are folded back by a cord, the rim being a normal rim, the normal state being when the tire is mounted on the rim and the internal pressure of the tire is adjusted to the normal internal pressure, the standard grounding state being when a load of 50% of the normal load is applied to the tire in the normal state and the tire is in contact with a flat surface, and in the standard grounding state the RFID tag is located in the axial direction between the axial outer end of the rim and the maximum width position of the tire, and in the radial direction between the radial outer end of the rim and the maximum width position of the tire.

[0022] By arranging the tire in this way, the RFID tag is positioned away from areas where its presence could cause significant distortion, such as near the edge of the rim flange and near the tire's widest point. In this tire, the presence of the RFID tag is suppressed as it contributes to increased distortion. Therefore, damage caused by the presence of the RFID tag is suppressed in this tire. Moreover, damage to the RFID tag itself is also suppressed. Despite having an integrated RFID tag, this tire maintains excellent durability.

[0023] [Configuration 2] Preferably, in the tire described in [Configuration 1] above, in the standard ground contact state, the RFID tag is located in the axial direction between the end of the folded portion and the maximum width position of the carcass, and in the radial direction between the end of the folded portion and the maximum width position of the carcass. By arranging the tire in this way, the RFID tag is positioned sufficiently far away from the flange ends and the widest point, areas where significant distortion could occur if the RFID tag is present. In this tire, the presence of the RFID tag effectively suppresses the increase in distortion. In this tire, the occurrence of damage caused by the presence of the RFID tag is effectively suppressed. Moreover, damage to the RFID tag itself is effectively suppressed. In this tire, good durability is maintained despite the presence of the RFID tag.

[0024] [Configuration 3] Preferably, in the tire described in [Configuration 1] or [Configuration 2] above, the shortest distance from the outer surface of the tire to the RFID tag is 3.5 mm or more. By arranging the tire in this way, the RFID tag is covered with rubber of sufficient thickness. In this tire, the presence of the RFID tag effectively suppresses the increase in strain. In this tire, the occurrence of damage caused by the presence of the RFID tag is effectively suppressed.

[0025] [Structure 4] Preferably, in the tire described in any of the above-described configurations [1] to [3], in the meridional cross-section of the tire in the normal state, the contour of the carcass comprises, radially inward at the maximum width position of the carcass, a curved portion that bulges outward and a reverse curved portion that is located radially inward of the curved portion and recesses inward, the reverse curved portion being continuous with the curved portion, the boundary between the curved portion and the reverse curved portion being an inflection point, part or all of the curved portion being represented by a first arc including the inflection point, part or all of the reverse curved portion being represented by a second arc including the inflection point, the first arc and the second arc being tangent at the inflection point, and the RFID tag being located radially outward from the inflection point. By arranging the tire in this way, the presence of the RFID tag effectively suppresses the increase in distortion. In this tire, the occurrence of damage caused by the presence of the RFID tag is effectively suppressed. Moreover, damage to the RFID tag itself is also effectively suppressed. In this tire 2, good durability is maintained despite the presence of the RFID tag.

[0026] [Composition 5] Preferably, in the tire described in any of the above-described configurations 1 to 4, the apex comprises an inner apex located radially outward of the core and an outer apex located radially outward of the inner apex, wherein the outer apex is softer than the inner apex, the tag member contacts the outer apex radially outward of the end of the folded portion, and the RFID tag is located radially between the outer end of the outer apex and the end of the folded portion. By arranging the tire in this way, the soft outer apex is positioned axially inward of the RFID tag, effectively suppressing the increase in distortion caused by the presence of the RFID tag. In this tire, the occurrence of damage caused by the presence of the RFID tag is suppressed. Moreover, damage to the RFID tag itself is also suppressed. In this tire, good durability is maintained despite the presence of the RFID tag. Furthermore, since the outer apex is positioned between the carcass ply and the RFID tag, the RFID tag is positioned with a gap between it and the carcass ply. Even if the carcass ply contains steel cord as the carcass cord, radio wave interference is less likely to occur, so a good communication environment is formed between the RFID tag and the communication device (not shown). Data is written to the RFID tag and read from the RFID tag accurately.

[0027] [Composition 6] Preferably, in the tire described in any of the above-mentioned configurations 1 to 5, the outer end of the chafer is located radially outward of the inner end of the sidewall, and the sidewall covers the outer end of the chafer. By aligning the tire in this way, the strain acting on the outer edge of the chafer is effectively mitigated. This reduces the occurrence of damage caused by the presence of RFID tags in the tire. Moreover, damage to the RFID tags themselves is also reduced. Despite the presence of embedded RFID tags, this tire maintains good durability.

[0028] [Composition 7] Preferably, in the tire described in any of the above-mentioned configurations [1] to [6], the tag member is provided on the side of the first sidewall of the pair of sidewalls. By arranging the tire in this way, the risk of damage can be reduced.

[0029] [Structure 8] Preferably, in the tire described in any of the above-mentioned [Configuration 1] to [Configuration 7], the tag member is a plate-shaped member in which the RFID tag is covered with cross-linked rubber, and the thickness of the tag member is 1.0 mm or more and 2.5 mm or less. By arranging the tires in this way, the risk of damage to RFID tags is reduced, and a good communication environment is created.

[0030] [Details of the Embodiments of the Invention] Figure 1 shows a part of a heavy-duty tire 2 (hereinafter also simply referred to as "tire 2") according to one embodiment of the present invention. This tire 2 is mounted on vehicles such as trucks and buses. In Figure 1, tire 2 is mounted on rim R (regular rim).

[0031] Figure 1 shows a portion of the cross-section of tire 2 (hereinafter referred to as the meridian cross-section) along the plane containing the rotation axis of tire 2. In Figure 1, the left-right direction is the axial direction of tire 2, and the up-down direction is the radial direction of tire 2. The direction perpendicular to the plane of paper in Figure 1 is the circumferential direction of tire 2. Figure 2 shows a portion of the cross-section shown in Figure 1. Figure 2 shows the bead portion of tire 2.

[0032] In Figure 1, the dashed line CL extending radially represents the equatorial plane of tire 2. In Figures 1 and 2, the solid line BBL extending axially is the bead baseline. The bead baseline is the line that defines the rim diameter of rim R (see JATMA, etc.).

[0033] This tire 2 comprises a tread 4, a pair of sidewalls 6, a pair of chafers 8, a pair of beads 10, a carcass 12, a belt 14, a pair of cushioning layers 16, a strip layer 18, a pair of steel reinforcement layers 20, an interlayer strip 22, an inner liner 24, and a tag member 26.

[0034] The tread 4 is located radially outward of the carcass 12. The tread 4 makes contact with the road surface at the tread surface 28. Grooves 30 are cut into the tread 4. The tread 4 comprises a base portion 32 and a cap portion 34 located radially outward from the base portion 32. The base portion 32 is made of low-heat-generating cross-linked rubber. The cap portion 34 is made of cross-linked rubber that takes wear resistance and grip performance into consideration. The cap portion 34 includes the tread surface 28.

[0035] In Figure 1, the position indicated by the symbol PC is the equator. The equatorial PC is the intersection of the tread surface 28 and the equatorial surface. When the groove 30 is located on the equatorial surface, as in this tire 2, the equatorial PC is determined based on a virtual tread surface obtained by assuming that the groove 30 does not exist. In a tire 2 in a normal state, the radial distance from the bead baseline to the equatorial PC is the cross-sectional height of the tire 2 (see JATMA, etc.).

[0036] Each sidewall 6 is connected to the edge of the tread 4. The sidewall 6 is located radially inward of the tread 4. The sidewall 6 is located axially outward of the carcass 12. The position indicated by the symbol PS is the inner end of the sidewall 6. Sidewall 6 is made of cross-linked rubber with cut resistance in mind. The complex modulus of elasticity of the sidewall is between 2.0 MPa and 6.0 MPa.

[0037] The position indicated by the symbol PW is the axial outer end of tire 2 (hereinafter referred to as outer end PW). If there are decorations such as patterns or letters on the outer surface, outer end PW is determined based on a hypothetical outer surface obtained assuming there are no decorations. Tire 2 shows its maximum width at outer end PW. Outer end PW is also called the maximum width position. In this invention, the maximum width position PW in the tire 2 in its normal state is the reference maximum width position PWb. The axial distance from the first reference maximum width position PWb to the second reference maximum width position PWb (not shown) is the cross-sectional width of the tire 2 (see JATMA, etc.).

[0038] In Figure 1, the length indicated by the symbol H is the radial distance from the bead baseline to the reference maximum width position PWb. The radial distance H is also called the radial height of the reference maximum width position PWb. In a tire 2 in its normal state, the ratio of the radial height H at the reference maximum width position PWb to the cross-sectional height is between 0.40 and 0.60.

[0039] Each chafer 8 is located radially inward of the sidewall 6. The chafer 8 is in contact with the rim R. The position indicated by the symbol PB is the outer end of the chafer 8. Chafer 8 is made of cross-linked rubber with abrasion resistance considered. The complex modulus of Chafer 8 is between 10 MPa and 15 MPa. Chafer 8 is harder than Sidewall 6.

[0040] Each bead 10 is located axially inward of the chafer 8. The bead 10 is located radially inward of the sidewall 6. The bead 10 comprises a core 36 and an apex 38.

[0041] The core 36 extends in the circumferential direction. The core 36 comprises a core body 36m and a wrapping layer 36r. The core body 36m is a ring extending in the circumferential direction. The core body 36m contains a steel wire wound in the circumferential direction. The cross-sectional shape of the core body 36m is determined by winding the wire in a regular manner. As a result, in the cross-section of the core body 36m, multiple cross-sectional units consisting of multiple wire cross-sections arranged in parallel in the axial direction are stacked in multiple layers in the approximately radial direction. The cross-sectional shape of the core body 36m is represented by a line circumscribing the core body 36m. As shown in Figure 1, the core body 36m has a hexagonal cross-sectional shape. This core body 36m may also have a square cross-sectional shape.

[0042] The core body 36m has approximately six sides 36ms. As shown in Figure 1, one of the six sides 36msb is positioned to face the sheet Rs of the rim R. In this disclosure, the side 36msb positioned to face the sheet Rs of the rim R is the bottom surface of the core body 36m. The core body 36m has a bottom surface 32msb positioned to face the sheet Rs of the rim R. In the meridional cross-section of the tire 2, the contour of the bottom surface 32msb is represented by a straight line.

[0043] The wrapping layer 36r surrounds the core body 36m. The wrapping layer 36r covers the core body 36m. The wrapping layer 36r prevents the core body 36m from falling apart. The wrapping layer 36r only needs to prevent the core body 36m from unraveling, and there are no particular restrictions on its composition. The wrapping layer 36r consists of a cord wound spirally around the core body 36m, or a rubberized cloth wrapped around the core body 36m, etc.

[0044] Apex 38 is located radially outward from core 36. Apex 38 extends radially outward from core 36. Apex 38 tapers outward. The outer end PA of apex 38 is located radially outward from the outer end PB of chafer 8.

[0045] Apex 38 comprises an inner apex 40 and an outer apex 42. The inner apex 40 is located radially outward from the core 36. The outer apex 42 is located radially outward from the inner apex 40.

[0046] The inner apex 40 tapers outward. The inner apex 40 is composed of rigid cross-linked rubber. The complex modulus of elasticity of the inner apex 40 is between 60 MPa and 90 MPa.

[0047] The outer apex 42 is thicker near the outer end PU of the inner apex 40. The outer apex 42 tapers inward and outward from this thicker portion. The inner end PG1 of the outer apex 42 is located near the core 36. The outer end PG2 of the outer apex 42 is also the outer end PA of the apex 38.

[0048] In Figure 2, the length indicated by the symbol L1 is the radial distance from the bead baseline to the outer end PG2 of the outer apex 42. The radial distance L1 is also called the radial height of the outer end PG2 of the outer apex 42. The outer end PG2 of the outer apex 42 is also the outer end PA of the apex 38. This radial distance L1 is also called the radial height of the bead 10.

[0049] In this tire 2, from the perspective of balancing the rigidity of the bead section and the deflection of the tire 2, the ratio (L1 / H) of the radial height L1 of the bead 10 to the radial height H of the maximum width position PWb is adjusted to a range of 0.55 to 0.95.

[0050] The outer apex 42 is made of cross-linked rubber. The outer apex 42 is softer than the inner apex 40. The complex modulus of elasticity of the outer apex 42 is between 3.0 MPa and 6.0 MPa.

[0051] This tire 2's apex 38 also features an edge strip 44. The edge strip 44 is located axially outward of the outer apex 42 and forms part of the outer surface of the apex 38. In the radial direction, the edge strip 44 is located between the outer end PB of the chafer 8 and the inner end PG1 of the outer apex 42. The edge strip 44 is made of cross-linked rubber. The edge strip 44 is softer than the chafer 8 and harder than the outer apex 42. The complex modulus of elasticity of the edge strip 44 is between 7.0 MPa and 12 MPa.

[0052] The carcass 12 is located inside the tread 4, a pair of sidewalls 6, and a pair of chafers 8. The carcass 12 spans between a pair of beads 10. The carcass 12 of this tire 2 has a radial structure.

[0053] The carcass 12 comprises at least one carcass ply 46. The carcass 12 of this tire 2 consists of one carcass ply 46. The carcass ply 46 is folded over at each bead 10.

[0054] The carcass ply 46 comprises a ply body 48 and a pair of folded portions 50. The ply body 48 spans between a pair of beads 10, i.e., between a first bead 10 and a second bead 10 (not shown). Each folded portion 50 is connected to the ply body 48 and is folded over by the bead 10. The folded portions 50 of this tire 2 are folded over by the bead 10 from the axially inward to the outward. The end PF of the folded portion 50 is located radially inward of the outer end PB of the chafer 8. The bead 10 is sandwiched between the ply body 48 and the folded portion 50.

[0055] Although not shown in the illustration, the carcass ply 46 contains numerous parallel carcass cords. These carcass cords are covered with topping rubber. Each carcass cord intersects the equatorial plane. The material of the carcass cords is steel. The carcass cords are steel cords.

[0056] In Figure 1, the length indicated by the symbol N is the radial distance from the bead baseline to the end PF of the folded portion 50. The radial distance N is also called the radial height of the end PF of the folded portion 50. In this tire 2, the ratio (N / H) of the radial height N of the end PF of the folded portion 50 to the radial height H of the reference maximum width position PWb is 0.25 or more and 0.45 or less.

[0057] The belt 14 comprises four belt plies 52. The four belt plies 52 are the first belt ply 52A, the second belt ply 52B, the third belt ply 52C, and the fourth belt ply 52D. These belt plies 52 are arranged radially. In this tire 2, the second belt ply 52B has the widest width, and the fourth belt ply 52D has the narrowest width.

[0058] Although not shown in the diagram, each belt ply 52 contains numerous parallel belt cords. Each belt cord is inclined with respect to the equatorial plane. The belt cords are made of steel.

[0059] Each cushion layer 16 is located between the belt 14 and the carcass 12 at the end of the belt 14. The cushion layer 16 is made of soft cross-linked rubber.

[0060] The strip layer 18 is located radially inward of the tread 4, between the carcass 12 and the belt 14. In the axial direction, the strip layer 18 is located between the first cushion layer 16 and the second cushion layer 16. The strip layer 18 is made of cross-linked rubber.

[0061] Each steel reinforcement layer 20 is located in the bead. The steel reinforcement layer 20 is located between the bead 10 and the chafer 8. The steel reinforcement layer 20 is located between the carcass 12 and the chafer 8. The steel reinforcement layer 20 is folded over at the bead 10. The steel reinforcement layer 20 is positioned to wrap around the radially inner portion of the bead 10 from the radially inner side of the folded portion 50. The inner end 20s and outer end 20f of the steel reinforcement layer 20 are located radially between the end PF of the folded portion 50 and the core 36. Although not shown in the diagram, the steel reinforcement layer 20 contains numerous parallel filler cords. The filler cords are made of steel. The steel reinforcement layer 20 contains steel cords. In the steel reinforcement layer 20, the steel cords are covered with topping rubber.

[0062] The outer end 20f of the steel reinforcement layer 20 is located between the folded portion 50 and the chafer 8 in the axial direction. The outer end 20f is located radially inward of the end PF of the folded portion 50. The inner end 20s is located between the inner liner 24 and the ply body 48 in the axial direction. The radial position of the inner end 20s should be approximately the same as that of the outer end 20f, and the inner end 20s may be located radially outward of the outer end 20f or radially inward of the outer end 20f.

[0063] Each interlayer strip 22 is positioned axially between the chafer 8 and the apex 38. The interlayer strips 22 cover the end PF of the folded portion 50 and the outer end 20f of the steel reinforcement layer 20. The interlayer strip 22 contacts the apex 38 on the radially outer side of the end PF of the folded portion 50. In other words, the contact surface between the interlayer strip 22 and the apex 38 constitutes a part of the outer surface of the apex 38 (or the inner surface of the interlayer strip 22). The interlayer strip 22 contacts the chafer 8 on the radially outer side of the outer end 20f of the steel reinforcement layer 20. In other words, the contact surface between the interlayer strip 22 and the chafer 8 constitutes a part of the inner surface of the chafer 8 (or the outer surface of the interlayer strip 22). The interlayer strip 22 is made of cross-linked rubber. The interlayer strip 22 is harder than the sidewall 6 and softer than the chafer 8. The complex modulus of elasticity of the interlayer strip 22 is between 7.0 MPa and 12 MPa.

[0064] The inner liner 24 is located inside the carcass 12. The inner liner 24 is bonded to the inner surface of the carcass 12 via an insulation (not shown) made of cross-linked rubber. The inner liner 24 constitutes the inner surface of the tire 2. The inner liner 24 is made of cross-linked rubber with excellent air-shielding properties.

[0065] The tag member 26 is located axially outward of the bead 10. In this tire 2, the tag member 26 is provided only on the side of the first sidewall 6. The tag member 26 may be provided on both the side of the first sidewall 6 and the side of the second sidewall 6. From the viewpoint of reducing the risk of damage, it is preferable that the tag member 26 be provided on the side of the first sidewall 6 of the pair of sidewalls 6.

[0066] Figure 3 is a plan view of the tag member 26. Figure 4 is a cross-sectional view along the line IV-IV in Figure 3. The tag member 26 is plate-shaped. The tag member 26 is long in the length direction and short in the width direction. As shown in Figure 1, in the tire 2, the tag member 26 is positioned such that its first end 26s in the width direction is radially outward of the tire 2, and its second end 26u is inward. In this tire 2, the first end 26s is also called the outer end, and the second end 26u is also called the inner end.

[0067] The tag member 26 includes an RFID tag 54. In Figure 3, the RFID tag 54 is shown with a solid line for illustrative purposes, but its entirety is covered by a protective body 56. The tag member 26 comprises the RFID tag 54 and the protective body 56. The RFID tag 54 is located in the center of the tag member 26. The protective body 56 is made of cross-linked rubber. The protective body 56 has a rigidity similar to that of the outer apex 42. In this tire 2, the formation of a good communication environment is considered, and cross-linked rubber with high electrical resistance is used for the protective body 56. The protective body 56 is made of highly insulating rubber.

[0068] Although not described in detail here, the RFID tag 54 is a small, lightweight electronic component consisting of a semiconductor chip 58 that integrates the transmitting and receiving circuits, control circuit, memory, etc., and an antenna 60. When the RFID tag 54 receives a query radio wave, it uses this as electrical energy to transmit various data stored in its memory as a response radio wave. This RFID tag 54 is a type of passive radio frequency identification transponder.

[0069] The tag member 26 is a plate-shaped member in which the RFID tag 54 is covered with cross-linked rubber. From the viewpoint of reducing the risk of damage to the RFID tag 54 and forming a good communication environment, the thickness of the tag member 26 in the tire 2 is preferably 1.0 mm or more and 2.5 mm or less. This thickness of the tag member 26 in the tire 2 is represented by the maximum thickness of the tag member 26 in the semiconductor chip 58 of the RFID tag 54. The length TL of the tag member 26 before it is embedded in the tire 2 is 60 mm or more and 80 mm or less. The width TW is 10 mm or more and 20 mm or less.

[0070] In Figure 2, the position indicated by the symbol TU is the radial inner end of the RFID tag 54 (specifically, the semiconductor chip 58). The position indicated by the symbol TS is the radial outer end of the semiconductor chip 58, i.e., the radial outer end of the RFID tag 54. In this invention, when the inner end TU of the RFID tag 54 in the tire 2 is located radially outward from a reference position (hereinafter referred to as the reference position), the RFID tag 54 is located radially outward from the reference position. When the outer end TS of the RFID tag 54 in the tire 2 is located radially inward from the reference position, the RFID tag 54 is located radially inward from the reference position.

[0071] Figure 5 shows a portion of the meridional cross-section of tire 2 in a ground-contact state. The cross-section in Figure 5 is a trace of a cross-sectional image of tire 2 taken, for example, by computed tomography using X-rays (hereinafter referred to as X-ray CT), with tire 2 in a normal state subjected to a load of 50% of the normal load and in contact with a planar FS. In this invention, the state in which a tire 2 in its normal state is subjected to a load of 50% of its normal load and the tire 2 is in contact with a flat surface FS is also called the standard contact state. In the standard contact condition shown in Figure 5, the tire camber angle is set to 0 degrees.

[0072] In Figure 5, the position indicated by the symbol PRa is the axial outer end of the flange Rf of the rim R. The dashed line indicated by the symbol LRa is a straight line that passes through the axial outer end PRa and extends radially. The position indicated by the symbol PRr is the radial outer end of flange Rf. The dashed line indicated by the symbol LRr is a straight line that passes through the radial outer end PRr and extends axially. In Figure 5, the position indicated by the symbol PWs is the position of the maximum width of tire 2 in the standard contact condition. The dashed line indicated by the symbol LWsa is a straight line that passes through the maximum width position PWs and extends radially. The dashed line indicated by the symbol LWsr is a straight line that passes through the maximum width position PWs and extends axially.

[0073] As shown in Figure 5, in the standard grounding state, the RFID tag 54 is located axially between the axial outer end PRa of the rim R and the maximum width position PWs of the tire 2, and radially between the radial outer end PRr of the rim R and the maximum width position PWs. In other words, the RFID tag 54 is located in the region enclosed by the dashed lines LWsr and LWsa, and the dashed lines LRr and LRa.

[0074] In this tire 2, the RFID tag 54 is positioned away from the edges of the flange Rf and the maximum width position PWs, where its presence could cause significant distortion. In this tire 2, the presence of the RFID tag 54 is suppressed from contributing to increased distortion. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is suppressed. Moreover, damage to the RFID tag 54 itself is also suppressed. Despite having an integrated RFID tag 54, this tire 2 maintains good durability.

[0075] Figure 6 shows a portion of the meridian cross-section of tire 2 in a ground-contact state. Figure 6 shows the same cross-section as shown in Figure 5.

[0076] In Figure 6, the dashed line denoted by LFa is a straight line that passes through the end PF of the folded portion 50 and extends radially. The dashed line denoted by LFr is a straight line that passes through the end PF of the folded portion 50 and extends axially. In Figure 6, the position indicated by the symbol PPs is the position of the maximum width of the carcass 12 under standard grounding conditions. The dashed line indicated by the symbol LPsa is a straight line extending radially through the maximum width position PPs. The dashed line indicated by the symbol LPsr is a straight line extending axially through the maximum width position PPs.

[0077] As shown in Figure 6, in the standard grounding state, the RFID tag 54 is located axially between the end PF of the folded portion 50 and the maximum width position PPs of the carcass 12, and radially between the end PF of the folded portion 50 and the maximum width position PPs of the carcass 12. In other words, the RFID tag 54 is located in the region enclosed by the dashed lines LPsr and LPsa, and the dashed lines LFr and LFa.

[0078] In this tire 2, the RFID tag 54 is positioned sufficiently far from the edges of the flange Rf and the maximum width position PWs, where the presence of the RFID tag 54 could cause significant distortion. In this tire 2, the presence of the RFID tag 54 effectively suppresses the increase in distortion. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is effectively suppressed. Moreover, damage to the RFID tag 54 itself is also effectively suppressed. In this tire 2, good durability is maintained despite the inclusion of an RFID tag 54. From this perspective, in this tire 2, under standard ground contact conditions, it is preferable that the RFID tag 54 is located axially between the end PF of the folded portion 50 and the maximum width position PPs of the carcass 12, and radially between the end PF of the folded portion 50 and the maximum width position PPs of the carcass 12.

[0079] In Figure 1, the length indicated by the double-headed arrow t represents the shortest distance from the outer surface of the tire 2 to the RFID tag 54. The shortest distance t is the thickness of the rubber covering the RFID tag 54.

[0080] In this tire 2, the shortest distance t is preferably 3.5 mm or more. This ensures that the RFID tag 54 is covered with rubber of sufficient thickness. In this tire 2, the presence of the RFID tag 54 effectively suppresses the increase in strain. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is effectively suppressed. From this viewpoint, a shortest distance t of 4.0 mm or more is more preferable. However, since the upper limit of this shortest distance t varies depending on the position of the RFID tag 54, no preferred upper limit for the shortest distance t is set.

[0081] Figure 7 shows the contour CL of the carcass 12 in the meridional cross-section of the tire 2 in a normal state. The contour CL of the carcass 12 shown in Figure 7 can be identified, for example, using a cross-sectional image of the tire 2 taken by the aforementioned X-ray CT method. In this case, the cross-sectional image of the tire 2 taken by the X-ray CT method is imported into CAD (Computer-Aided Design), and the contour CL of the carcass 12 is identified on this CAD.

[0082] Figure 8 shows a portion of the meridional cross-section of the tire 2. As shown in Figure 8, the contour PL of the carcass 12 is represented by a line obtained by connecting the centers of the carcass cords 62 contained in the ply body 48. Figure 9 shows a modified example of the carcass 12, specifically when the carcass 12 is composed of multiple carcass plies 46, and specifically when the carcass 12 is composed of two carcass plies 46. In this case, in the cross-section shown in Figure 9, the contour PL of the carcass 12 is represented by a line obtained by connecting the centers of the inner edge 62n of the carcass cords 62 contained in the inner ply body 48 and the outer edge 62g of the carcass cords 62 contained in the outer ply body 48. Although not labeled, in Figures 8 and 9, the elements located on both sides of the carcass cords 62 are topping rubber covering the carcass cords 62.

[0083] In Figure 7, the position indicated by the symbol PE is the intersection of the carcass 12 contour PL (hereinafter referred to as the case line PL) and the equatorial plane. Intersection PE is the equator on the case line PL. The length indicated by the symbol CH is the radial distance from the bead baseline to the equatorial PE. In this tire 2, the equator PE coincides with the radial outer end of the case line PL. The radial distance CH is also the cross-sectional height of the carcass 12.

[0084] In Figure 7, the position indicated by the symbol PPb is the axial outer end of the case line PL in the normal state. In the normal state of tire 2, the case line PL shows its maximum width at the axial outer end PPb. This axial outer end PPb is also called the position of maximum width of the case line PL (or the position of maximum width of the carcass 12). The length indicated by the symbol CW is the axial distance from the equatorial plane to the axial outer end PPb. Although not shown in Figure 2, the outer end PA of the apex 38 is located radially inward from the axial outer end PPb.

[0085] In Figure 7, the position indicated by the symbol ME is the radial outer end of the core body 36m. The solid line indicated by the symbol ML is a straight line that passes through the radial outer end ME and extends axially. The position indicated by the symbol PM is the intersection of the line ML and the case line PL. Intersection PM is the position on the case line PL corresponding to the radial outer end ME of the core body 36m. Intersection PM is the reference point of the case line PL.

[0086] In this tire 2, the case line PL is constructed by combining multiple arcs, connecting them with straight lines where necessary. This case line PL has an outwardly convex shape in the tread area, an outwardly convex shape in the sidewall area and the radially outer portion of the bead area, and an inwardly concave shape in the radially inner portion of the bead area. The bead area has an inflection point where it bulges outward and concaves inward.

[0087] In this invention, "bulging outward" means a shape that curves from the inner surface to the outer surface of the tire, and "concave inward" means a shape that curves from the outer surface to the inner surface of the tire.

[0088] In this tire 2, the radially inward portion of the case line PL from the axial outer end PPb, specifically the portion from the axial outer end PPb to the reference point PM, includes an outwardly bulging curved portion 64 and an inwardly recessed inverted curved portion 66. In other words, in the meridional cross-section of the tire 2 in its normal state, the contour of the carcass 12 includes a curved portion 64 and an inverted curved portion 66 located radially inward of the curved portion 64, in the radially inward portion of the maximum width position PPb of the carcass 12. The inverted curved section 66 is located radially inward of the curved section 64 and is connected to it. The boundary between the curved section 64 and the inverted curved section 66 is the inflection point mentioned above. In Figure 7, the position indicated by the symbol PV is the inflection point.

[0089] The curved portion 64 of the tire 2 shown in Figure 7 is represented by a single circular arc. This arc has its center Ca on a straight line (solid line LPb in Figure 7) that passes through the axial outer end PPb and extends axially, and includes the axial outer end PPb and the inflection point PV. The arrow indicated by the symbol R1 in Figure 7 is the radius of this arc. Although not shown in the figures, in this tire 2, the curved portion 64 may be represented by an arc (hereinafter referred to as arc a) having its center on the straight line LPb and including the axial outer end PPb, and an arc (hereinafter referred to as arc b) tangent to arc a and including the inflection point PV. In this case, the center of arc b is located on a straight line passing through the center of arc a and the point of tangency between arc a and arc b. In this tire 2, an arc having its center on the straight line LPb and including the axial outer end PPb, and an arc including the inflection point PV, may be connected by one or more arcs. In this case, the curved portion 64 is represented by a plurality of arcs, including an arc having its center on the straight line LPb and including the axial outer end PPb, and an arc including the inflection point PV, and is configured such that two adjacent arcs are tangent to each other. In either case, the curved portion 64 includes an arc containing an inflection point PV. In the present invention, the arc passing through this inflection point PV is the first arc. In this tire 2, part or all of the curved portion 64 is represented by a first circular arc passing through the inflection point PV.

[0090] In the tire 2 shown in Figure 7, the reverse curved portion 66 is also represented by a single circular arc. This arc has its center Cb on a straight line (solid line LAB in Figure 2) passing through the center Ca of the arc representing the curved portion 64 (the first arc) and the inflection point PV, and includes the inflection point PV and the reference point PM. The arrow indicated by the symbol R2 in Figure 7 is the radius of this arc. Although not shown in the diagram, in this tire 2, the inverted curved portion 66 may be represented by an arc containing the inflection point PV (hereinafter referred to as arc c) and an arc tangent to arc c and containing the reference point PM (hereinafter referred to as arc d). In this case, the center of arc d is located on a straight line passing through the center of arc c and the point of tangency between arc c and arc d. In this tire 2, the arc containing the inflection point PV and the arc containing the reference point PM may be connected by one or more arcs. In this case, the inverted curved portion 66 is represented by multiple arcs, including the arc containing the inflection point PV and the arc containing the reference point PM, and is configured such that two adjacent arcs are tangent to each other. In either case, the inverted curved portion 66 includes an arc containing an inflection point PV. In this disclosure, the arc passing through this inflection point PV is the second arc.

[0091] If the configuration of the case line PL is unknown, the first arc representing the curved section 64, the second arc representing the reverse curved section 66, and the inflection point PV are obtained as follows. The case line PL is identified based on a cross-sectional image of a tire in a normal state, taken by X-ray CT. The axial outer end PPb of the case line PL is determined. An outward-convex arc (hereinafter referred to as the outward arc) is drawn, with its center on a straight line LPb that passes through the axial outer end PPb and extends axially, and including the axial outer end PPb. By drawing outward arcs with varying radii, the outward arc that maximizes the overlap length with the case line PL from the axial outer end PPb (hereinafter referred to as the first outward arc) is determined. If the entire curved portion 64 cannot be represented by this first outward arc, another outward arc is drawn with its center on a straight line passing through the end of the first outward arc and the center of this first outward arc. By drawing outward arcs with varying radii, the outward arc that maximizes the overlap length with the case line PL from the end of the first outward arc (hereinafter referred to as the second outward arc) is determined. The tracing of the case line PL with this outward arc is repeated until it can no longer be traced by the outward arc. The end of the last drawn outward arc on the core body 36m side is identified as the inflection point PV, and this outward arc is identified as the first arc that includes the inflection point PV and represents part or all of the curved portion 64. An inwardly convex arc (hereinafter referred to as an inward arc) is drawn on a straight line passing through the center of the first arc identified in this way and the inflection point PV, with its center on the opposite side of the inflection point PV from the center of the first arc, and including the inflection point PV. By drawing inward arcs while changing the radius, an inward arc (hereinafter referred to as the first inward arc) is found that maximizes the overlap length with the case line PL from the inflection point PV. This first inward arc is identified as the second arc, which includes the inflection point PV and represents part or all of the inverted curve 66. If the entire inverted curve 66 cannot be drawn with the first inward arc, tracing with inward arcs is repeated until the last inward arc including the reference point PM is drawn.

[0092] In this tire 2, part or all of the inverted curved portion 66 is represented by a second arc passing through the inflection point PV. The first arc representing part or all of the curved portion 46 and the second arc representing part or all of the inverted curved portion 66 are tangent at the inflection point PV. The inflection point PV is located between the center of the first arc and the center of the second arc, and the center of the first arc, the inflection point PV, and the center of the second arc lie on the same straight line. In the case line PL shown in Figure 7, the first arc representing the curved portion 64 and the second arc representing the reverse curved portion 66 are tangent at the inflection point PV. The inflection point PV is located between the center Ca of the first arc and the center Cb of the second arc, and the center Ca of the first arc, the inflection point PV, and the center Cb of the second arc lie on the same straight line LAB.

[0093] In tire 2, a particularly large load acts on the radially inner portion of the inflection point PV of the case line PL. Therefore, this radially inner portion of the inflection point PV is a region where distortion is likely to occur if foreign matter is present.

[0094] As shown in Figure 2, in this tire 2, the RFID tag 54 is located radially outward from the inflection point PV. This effectively suppresses the increase in strain caused by the presence of the RFID tag 54. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is effectively suppressed. Moreover, damage to the RFID tag 54 itself is also effectively suppressed. In this tire 2, good durability is maintained despite the inclusion of an RFID tag 54. From this perspective, it is preferable that the RFID tag 54 be located radially outward from the inflection point PV.

[0095] In Figure 7, the length indicated by the symbol X is the axial distance from the equatorial plane of tire 2 to the inflection point PV. The length indicated by the symbol Y is the radial distance from the bead baseline to the inflection point PV.

[0096] In this tire 2, the ratio (X / CW) of the axial distance X from the equatorial plane to the inflection point PV to the axial distance CW from the equatorial plane to the axial outer end PPb is preferably 70% to 85%, and the ratio (Y / CH) of the radial distance Y from the bead baseline to the inflection point PV to the radial distance CH from the bead baseline to the equator PE is preferably 15% to 22%.

[0097] By setting the ratio (X / CW) to 70% or higher and the ratio (Y / CH) to 15% or higher, the inflection point PV is positioned at an appropriate distance from the core 36. The RFID tag 54, located radially outside the inflection point PV, is effectively prevented from contributing to increased strain. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is effectively suppressed. Moreover, damage to the RFID tag 54 itself is also effectively suppressed. From this viewpoint, it is more preferable that the ratio (X / CW) is 75% or higher and the ratio (Y / CH) is 17% or higher. By setting the ratio (X / CW) to 85% or less and the ratio (Y / CH) to 22% or less, the inflection point PV is positioned at an appropriate distance from the maximum width position PPb. This suppresses deformation of the carcass 12 in the bead area when the tire 2 is inflated, and even in this case, the RFID tag 54 located radially outside the inflection point PV effectively prevents it from contributing to increased strain. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is effectively suppressed. Moreover, damage to the RFID tag 54 itself is also effectively suppressed. From this viewpoint, it is more preferable that the ratio (X / CW) is 80% or less and the ratio (Y / CH) is 20% or less.

[0098] In Figure 7, the solid line LV is the tangent to the case line CL at the inflection point PV. The solid line LT is a straight line that includes the line representing the contour of the bottom surface 36msb of the core body 36m in the meridional cross-section of tire 2. The angle θ is the angle between the tangent line LV and the straight line LT. In this invention, this angle θ is the angle between the tangent line LV of the contour of the carcass 12 at the inflection point PV and the line representing the contour of the bottom surface 32mcb.

[0099] In this tire 2, the angle θ is preferably between 25 degrees and 30 degrees. By setting the angle θ to 25 degrees or more, the collapse of the case line CL in the bead area is effectively suppressed. Since the distortion caused by the load is suppressed, the RFID tag 54, which is located radially outward from the inflection point PV, is effectively prevented from contributing to the increase in distortion. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is effectively suppressed. Moreover, damage to the RFID tag 54 itself is also effectively suppressed. From this viewpoint, an angle θ of 26 degrees or more is more preferable. By setting the angle θ to 30 degrees or less, deformation of the carcass 12 in the bead area during tire 2 inflation is suppressed. In this case as well, the RFID tag 54 located radially outward of the inflection point PV effectively suppresses its contribution to increasing strain. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is effectively suppressed. Moreover, damage to the RFID tag 54 itself is also effectively suppressed. From this viewpoint, an angle θ of 29 degrees or less is more preferable.

[0100] In this tire 2, the tag member 26 is located radially outward from the end PF of the folded portion 50 and axially outward from the outer apex 42. The tag member 26 is in contact with the outer apex 42. The boundary between the tag member 26 and the outer apex 42 constitutes a part of the outer surface of the outer apex 42. In other words, the boundary between the tag member 26 and the outer apex 42 constitutes a part of the outer surface of the apex 38. In this tire 2, the RFID tag 54 is located radially between the outer end PG2 of the outer apex 42 and the end PF of the folded portion 50. The RFID tag 54 on tire 2 is positioned in the bead area, where the degree of bending is minimal. The risk of damage to the RFID tag 54 is low in tire 2. Since the outer apex 42, which is softer than the inner apex 40, is located axially inward of the RFID tag 54, the presence of the RFID tag 54 effectively suppresses the increase in distortion. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is suppressed. Moreover, damage to the RFID tag 54 itself is also suppressed. In this tire 2, good durability is maintained despite the presence of the RFID tag 54. In this tire 2, the outer apex 42 is located between the carcass ply 46 and the RFID tag 54. The RFID tag 54 is positioned at a distance from the carcass ply 46, which includes the carcass cord, a metal element. Because radio wave interference is less likely to occur, a good communication environment is formed between the RFID tag 54 and the communication device (not shown). Data can be written to the RFID tag 54 and read from the RFID tag 54 accurately. From the viewpoint of maintaining good durability while achieving the formation of a good communication environment and reducing the risk of damage to the RFID tag 54, it is preferable that the tag member 26 contacts the outer apex 42 on the radially outer side of the end PF of the folded portion 50, and that the RFID tag 54 is located radially between the outer end PG2 of the outer apex 42 and the end PF of the folded portion 50. From a similar viewpoint, it is more preferable that the RFID tag 54 is located radially between the outer end PG2 of the outer apex 42 and the outer end PB of the chafer 8.

[0101] In this tire 2, the inner end 26u of the tag member 26 is located radially outward from the outer end PB of the chafer 8. In this tire 2, the entire tag member 26 is positioned radially outward from the outer end PB of the chafer 8. Since interference of the tag member 26 with the outer end PB of the chafer 8 is effectively suppressed, the undulation (i.e., the occurrence of creases) of the outer end PB of the chafer 8 is effectively suppressed. The presence of the RFID tag 54 is effectively suppressed from contributing to increased strain. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is suppressed. Moreover, damage to the RFID tag 54 itself is also suppressed. In this tire 2, good durability is maintained despite the presence of the RFID tag 54. From this viewpoint, it is preferable that in this tire 2, the inner end 26u of the tag member 26 is located radially outward from the outer end PB of the chafer 8.

[0102] In this tire 2, the outer end 26s of the tag member 26 is located radially inward of the outer end PG2 of the outer apex 42. This effectively suppresses the influence of the tag member 26 on the deflection of the sidewall. In this tire 2, good durability and ride comfort are maintained. From this viewpoint, it is preferable that the outer end 26s of the tag member 26 is located radially inward of the outer end PG2 of the outer apex 42.

[0103] In this tire 2, it is more preferable that the inner end 26u of the tag member 26 is located radially outward from the outer end PB of the chafer 8, and the outer end 26s of the tag member 26 is located radially inward from the outer end PG2 of the outer apex 42. In this case, as shown in Figure 2, the entire tag member 26 is positioned between the outer end PG2 of the outer apex 42 and the outer end PB of the chafer 8.

[0104] In this tire 2, the outer end PB of the chafer 8 is located radially outward of the inner end PS of the sidewall 6, and the sidewall 6 covers the outer end PB of the chafer 8. Since the outer end PB of the chafer 8 is covered by the sidewall 6, the strain acting on this outer end PB is effectively mitigated. In this tire 2, the chafer 8 is harder than the sidewall 6. Therefore, by covering the outer end PB of the chafer 8 with the sidewall 6, the strain acting on this outer end PB is more effectively mitigated. In this tire 2, the occurrence of damage caused by the presence of the RFID tag 54 is suppressed. Moreover, damage to the RFID tag 54 itself is also suppressed. In this tire 2, good durability is maintained despite the presence of the RFID tag 54. From this viewpoint, it is preferable that in this tire 2, the outer end PB of the chafer 8 is located radially outward of the inner end PS of the sidewall 6, and the sidewall 6 covers the outer end PB of the chafer 8.

[0105] In Figure 2, the length indicated by the symbol R1 is the radial distance from the bead baseline to the outer edge PB of the chafer 8. The radial distance R1 is also called the radial height of the outer edge PB of the chafer 8. In Figure 2, the length indicated by the symbol K2 is the radial distance from the bead baseline to the inner end PS of the sidewall 6. The radial distance K2 is also called the radial height of the inner end PS of the sidewall 6.

[0106] In this tire 2, the ratio (L1 / R1) of the radial height L1 of the outer end PG2 of the outer apex 42 to the radial height R1 of the outer end PB of the chafer 8 is preferably 1.08 or more and 1.54 or less. By setting the ratio (L1 / R1) to 1.08 or higher, space for the tag member 26 is secured. This tire 2 allows the tag member 26 to be positioned in a location that is less likely to interfere with the outer end PB of the chafer 8. In this tire 2, the presence of the RFID tag 54 effectively suppresses the increase in strain. From this viewpoint, a ratio (L1 / R1) of 1.12 or higher is more preferable. By setting the ratio (L1 / R1) to 1.54 or less, the influence of the outer apex 42 on the deflection of the tire 2 is suppressed. With this tire 2, a good ride comfort is maintained. From this viewpoint, a ratio (L1 / R1) of 1.42 or less is more preferable.

[0107] In this tire 2, it is preferable that the ratio (R1 / K2) of the radial height R1 of the outer end PB of the chafer 8 to the radial height K2 of the inner end PS of the sidewall 6 is between 2.00 and 3.25. By setting the ratio (R1 / K2) to 2.00 or higher, a sufficient joint area between the sidewall 6 and the chafer 8 can be secured. In this tire 2, the strain acting on the outer end PB of the chafer 8 is more effectively mitigated. In this tire 2, the presence of the RFID tag 54 is effectively suppressed from contributing to an increase in strain. From this viewpoint, a ratio (R1 / K2) of 2.20 or higher is more preferable. By setting the ratio (R1 / K2) to 3.25 or less, space for the tag member 26 is secured. This tire 2 allows the tag member 26 to be positioned in a location that is less likely to interfere with the outer end PB of the chafer 8. Even in this case, the presence of the RFID tag 54 effectively suppresses the increase in strain. From this viewpoint, a ratio (R1 / K2) of 3.00 or less is more preferable.

[0108] In this tire 2, the outer end PU of the inner apex 40 is located radially between the end PF of the folded portion 50 and the RFID tag 54. This allows the rigid inner apex 40 to effectively increase the rigidity of the bead portion. This effectively reduces the strain acting on the RFID tag 54. The presence of the RFID tag 54 effectively suppresses the increase in strain. From this viewpoint, it is preferable that the outer end PU of the inner apex 40 is located radially between the end PF of the folded portion 50 and the RFID tag 54. In this case, from the viewpoint of more effectively suppressing the increase in strain caused by the presence of the RFID tag 54, it is preferable that the outer end PU of the inner apex 40 is located radially between the end PF of the folded portion 50 and the RFID tag 54, and even more preferable that the outer end PU of the inner apex 40 is located radially between the end PF of the folded portion 50 and the outer end of the chafer 8.

[0109] As is clear from the above description, according to the present invention, a heavy-duty tire 2 can be obtained that can suppress the occurrence of damage caused by the presence of the RFID tag 54. [Industrial applicability]

[0110] The technology described above, which can suppress damage caused by the presence of RFID tags, can be applied to various types of tires. [Explanation of Symbols]

[0111] 2... Tires 4. Tread 6. Sidewall 8. Chafer 10...bead 12...Carcass 20. Steel reinforcement layer 22...Interlayer strip 26... Tag components 36 cores 38..Apex 40...Inner apex 42...Outer apex 44. Edge strip 46...Carcass ply 48...Ply body 50...Folded section 54. RFID tags 56. Protective body 58. Semiconductor chips 60... Antenna 62...Carcass Code 64... Curved section 66...Reverse curved part

Claims

1. A tire comprising a pair of beads, a carcass spanning the pair of beads, a pair of sidewalls located axially outward of the carcass, a pair of chafers located radially inward of the sidewalls and in contact with the rim, and a tag member including an RFID tag, The bead comprises a core and an apex located radially outward from the core. The carcass comprises a carcass ply, The carcass ply comprises a ply body that spans between a pair of beads, and a pair of folded portions that are connected to the ply body and folded back by the beads. The apex comprises an inner apex located radially outward of the core and an outer apex located radially outward of the inner apex. The aforementioned rim is a standard rim, The normal state is when the tire is mounted on the rim and the internal pressure of the tire is adjusted to the normal internal pressure. The standard contact condition is when a load of 50% of the normal load is applied to the tire in the normal state, causing the tire to contact a flat surface. In the standard grounding state, the RFID tag is positioned in the axial direction between the axial outer end of the rim and the maximum width position of the tire, and in the radial direction between the radial outer end of the rim and the maximum width position of the tire. The tag member is sandwiched between the outer apex and the sidewall. Heavy-duty tires.

2. In the standard grounding state, the RFID tag is located in the axial direction between the end of the folded portion and the maximum width position of the carcass, and in the radial direction between the end of the folded portion and the maximum width position of the carcass. A heavy-duty tire according to claim 1.

3. The shortest distance from the outer surface of the tire to the RFID tag is 3.5 mm or more. A heavy-duty tire according to claim 1 or 2.

4. In the meridional cross-section of the tire in the normal state, the contour of the carcass comprises, in the radially inward portion of the maximum width position of the carcass, an outwardly bulging curved portion and an inwardly recessed reverse curved portion located radially inward of the curved portion, The aforementioned reverse curved portion is connected to the curved portion, The boundary between the curved portion and the reverse curved portion is an inflection point. A part or all of the curved portion is represented by a first arc that includes the inflection point, A part or all of the aforementioned inverted curve is represented by a second arc containing the inflection point, The first arc and the second arc are tangent at the inflection point. The RFID tag is located radially outward from the inflection point. A heavy-duty tire according to claim 1 or 2.

5. The outer apex is softer than the inner apex, The tag member contacts the outer apex at the radially outer end of the folded portion. The RFID tag is located radially between the outer end of the outer apex and the end of the folded portion. A heavy-duty tire according to claim 1 or 2.

6. The outer end of the chafer is located radially outward from the inner end of the sidewall, The sidewall covers the outer end of the chafer. A heavy-duty tire as described in claim 5.

7. The tag member is a plate-shaped member in which the RFID tag is covered with cross-linked rubber. The thickness of the tag member is 1.0 mm or more and 2.5 mm or less. A heavy-duty tire according to claim 1 or 2.

Images