pneumatic tires

Abstract

The present invention provides a pneumatic tire that ensures rigidity in the land portion while also achieving a uniform rigidity balance across the entire land portion, even when a resonator is installed. [Solution] The device is equipped with multiple resonators 6, and the overlap amount, which is the circumferential length of the tire when the sub-grooves 6a and 10a of the resonators 6 formed on different land portions 3 are projected in the tire width direction, is 50% or less of the circumferential length of at least one of the sub-grooves 6a and 10a.

Description

Technical Field

[0001] The present invention relates to pneumatic tires.

Background Art

[0002] In pneumatic tires, it is required to reduce the noise during vehicle running and enhance quietness. In contrast, various pneumatic tires have been proposed that can reduce external noise such as the air column resonance sound generated from the circumferential main grooves provided on the tread surface of the pneumatic tire (which is often observed at about 800 to 1200 Hz in general passenger cars) by a resonator (so-called Helmholtz resonator) composed of a sub-groove and a branch groove (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the pneumatic tire described in Patent Document 1, due to the arrangement of the resonator (which is a groove), the rigidity of the land portion may decrease, and there is a risk that the handling stability and the like may decrease. In addition, due to the arrangement of the resonator, a portion where the rigidity locally decreases occurs, and the rigidity balance of the entire land portion is non-uniform.

[0005] Therefore, an object of the present invention is to provide a pneumatic tire that can ensure the rigidity of the land portion and uniformize the rigidity balance of the entire land portion even when a resonator is arranged.

Means for Solving the Problems

[0006] The gist configuration of the present invention is as follows. (1) A pneumatic tire comprising a tread surface having a plurality of land areas, each land area having a secondary groove that terminates within the land area and at least one branch groove that connects the secondary groove to the circumferential main groove, wherein the land area is equipped with a plurality of resonators, each having a secondary groove that terminates within the land area and at least one branch groove that connects the secondary groove to the circumferential main groove, A pneumatic tire characterized in that the overlap amount, which is the tire circumferential length when the sub-grooves of the resonators formed in different land portions are projected in the tire width direction, is 50% or less of the tire circumferential length of at least one of the sub-grooves.

[0007] Here, "tread surface" refers to the entire circumferential surface of the tire that comes into contact with the road surface when a pneumatic tire is mounted on an applicable rim, filled to the specified internal pressure, and subjected to the maximum load. Furthermore, "circumferential main grooves" refer to grooves that extend in the circumferential direction of the tire and have a groove width (opening width) of 2 mm or more. Furthermore, "the circumferential length of the secondary groove" refers to the maximum length in the circumferential direction of the tire. In this specification, unless otherwise specified, dimensions and shapes refer to the dimensions and shapes of a pneumatic tire when it is mounted on the applicable rim, filled to the specified internal pressure, and unloaded.

[0008] In this specification, "applicable rim" refers to the standard rim for the applicable size (Measuring Rim in the ETRTO STANDARDS MANUAL, Design Rim in the TRA YEAR BOOK) which is an industrial standard valid in the region where the tire is produced and used, and which is listed or will be listed in the future in the STANDARDS MANUAL of the ETRTO (The European Tyre and Rim Technical Organisation) in Japan, the STANDARDS MANUAL of the ETRTO (The European Tyre and Rim Technical Organisation) in Europe, and the YEAR BOOK of the TRA (The Tire and Rim Association, Inc.) in the United States, etc. (That is, the "rim" in "wheel" above includes not only current sizes but also sizes that may be included in the above industrial standards in the future. An example of "sizes to be listed in the future" is the size listed as "FUTURE DEVELOPMENTS" in the ETRTO 2013 edition.) However, in the case of a size not listed in the above industrial standards, it refers to a rim with a width corresponding to the tire bead width. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size and ply rating as described in JATMA, etc., and in the case of sizes not listed in the above industrial standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Furthermore, "maximum load capacity" refers to the load corresponding to the maximum load capacity mentioned above.

[0009] (2) The pneumatic tire according to (1), wherein the overlap amount is 50% or less of the tire circumferential length of both sub-grooves.

[0010] (3) The pneumatic tire according to (1) or (2), wherein the sum of the circumferential lengths of the tire in the tire circumferential regions where the resonators are not located in any of the land portions is 40 to 60% of the total circumference of the tire.

[0011] (4) The pneumatic tire according to any one of (1) to (3), wherein the secondary groove of the resonator located on one of the different land sections is arranged to extend in one direction in the tire circumferential direction relative to the branch groove, and the secondary groove of the resonator located on the other land section of the different land section is arranged to extend in the other direction in the tire circumferential direction relative to the branch groove. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a pneumatic tire that can ensure the rigidity of the land portion while uniformizing the rigidity balance of the entire land portion, even when a resonator is installed. [Brief explanation of the drawing]

[0013] [Figure 1] This is an exploded view showing the tread surface of a pneumatic tire according to one embodiment of the present invention. [Figure 2] This diagram shows an example of the layout of communication equipment. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0015] Figure 1 is an exploded view showing the tread surface of a pneumatic tire (hereinafter also simply referred to as "tire") according to one embodiment of the present invention. As shown in Figure 1, this tire has a plurality of land areas 3 on the tread surface 1, each of which at least one side in the tire width direction is demarcated by a circumferential main groove 2 extending in the tire circumferential direction.

[0016] In the illustrated example, the tread surface 1 has four circumferential main grooves 2. Circumferential main grooves 2a and 2b are arranged in one half of the tire width direction (which can be the outer side when mounted on a vehicle) with the tire equatorial plane CL as the boundary, while circumferential main grooves 2c and 2d are arranged in the other half of the tire width direction (which can be the inner side when mounted on a vehicle).

[0017] On one half in the tire width direction, the land portion 3a is demarcated by the tread edge TE and the circumferential main groove 2a, and a land portion 3b is demarcated between the circumferential main groove 2a and the circumferential main groove 2b. Also, a land portion 3c is located on the tire equatorial plane CL, and the land portion 3c is demarcated between the circumferential main groove 2b and the circumferential main groove 2c. On the other half in the tire width direction, a land portion 3d is demarcated between the circumferential main groove 2c and the circumferential main groove 2d, and a land portion 3e is demarcated by the tread edge TE and the circumferential main groove 2d.

[0018] In the present embodiment, an example in which the number of the circumferential main grooves 2 is four, and thus five land portions 3 are demarcated and formed is shown, but the number of the circumferential main grooves 2 can be three or less or five or more, and thus the number of the land portions 3 can also be four or less or six or more. Also, the arrangement in the tire width direction of the plurality of circumferential main grooves 2 can be various, and a circumferential main groove 2 extending on the tire equatorial plane CL may be located, or the number of the circumferential main grooves 2 may be made different between the half portions in the tire width direction with the tire equatorial plane CL as a boundary.

[0019] In the illustrated example, the circumferential main groove 2 extends straight in the tire circumferential direction, but it may extend in a zigzag shape, a curved shape, or a bent shape. Also, in the illustrated example, the circumferential main groove 2 extends without inclining with respect to the tire circumferential direction, but it may extend while inclining at an inclination angle of 5° or less with respect to the tire circumferential direction. Also, as described above, the groove width of the circumferential main groove 2 is 2 mm or more. The groove width (opening width) of the circumferential main groove 2 is not particularly limited, but can be, for example, 17 mm or less. Also, the groove depth (maximum depth) of the circumferential main groove 2 is not particularly limited, but can be, for example, 8.2 to 9.5 mm.

[0020] The circumferential main groove 2 may have a widened portion on the groove bottom side where the groove width is larger than that on the tread surface 1 side. This is because the drainage performance during wear progress can be improved. In particular, it is preferable that only the circumferential main grooves 2a and 2b formed in one half in the tire width direction (the outer side when mounted on a vehicle) have the widened portion. The groove width of the widened portion is not particularly limited, but can be, for example, 6 to 20 mm.

[0021] The land portion 3a is the outermost land portion in the tire width direction of one half on one side in the tire width direction (which can be the outer side when mounted on a vehicle). In the land portion 3a, a plurality of width direction sipes 4 extending from the tread edge TE to the circumferential main groove 2a and a plurality of width direction sipes 5 extending from the tread edge TE and terminating within the land portion 3a are alternately arranged in the tire circumferential direction. The width direction sipes 4 and 5 can extend without inclination with respect to the tire width direction, or can extend inclined with respect to the tire width direction (for example, at an inclination angle of 1 to 10°). In the illustrated example, the width direction sipes 4 and 5 are arranged one per pitch, but it is not limited to this case.

[0022] The land portion 3b is an intermediate land portion adjacent to the outermost land portion in the tire width direction of one half on one side in the tire width direction (which can be the outer side when mounted on a vehicle). In the land portion 3b, a plurality of resonators 6 having a sub-groove 6a terminating within the land portion 3b and at least one (one in the illustrated example) branch groove 6b connecting the sub-groove 6a and the circumferential main groove 2b are arranged. The plurality of resonators 6 are arranged spaced apart in the tire circumferential direction. In this example, they are arranged approximately one per two pitches (the distance between the two-dot chain lines is one pitch). The groove width, groove depth, etc. of the sub-groove 6a and the branch groove 6b can be appropriately set according to the specifications of the circumferential main groove 2b that generates the air column resonance sound to be reduced.

[0023] In the land portion 3b, a plurality of width direction sipes 7 and 8 are arranged. In the illustrated example, the width direction sipes 7 have a bent shape, but it is not limited to this case. The width direction sipes 7 extend from the circumferential main groove 2b, bend, and then terminate within the land portion 3b. The width direction sipes 8 are located on approximately the extension line of the width direction outer portion of the width direction sipes 7.

[0024] The land portion 3c is the central land portion located on the tire equatorial plane CL. Multiple widthwise sipes 9 are arranged on the land portion 3c. The widthwise sipes 9 can extend without inclination relative to the tire width direction, or they can extend at an inclination relative to the tire width direction (for example, at an inclination angle of 20 to 40°). In the illustrated example, one widthwise sipe 9 is arranged per pitch, but this is not limited to this case. In the illustrated example, the widthwise sipes 9 terminate within the land portion 3c.

[0025] The land portion 3d is an intermediate land portion adjacent to the outermost land portion in the tire width direction on the other half in the tire width direction (which can be the inner side when mounted on a vehicle). The land portion 3d is equipped with a plurality of resonators 10, each having a sub-groove 10a that terminates within the land portion 3d and at least one (one in the illustrated example) branch groove 10b that connects the sub-groove 10a to the circumferential main groove 2c. The plurality of resonators 10 are spaced apart in the circumferential direction of the tire, with one resonator approximately every two pitches (one pitch is between the dashed lines). The groove width, groove depth, etc., of the sub-groove 10a and branch groove 10b can be appropriately set according to the specifications of the circumferential main groove 2c that generates the air column resonance sound to be reduced.

[0026] Multiple widthwise sipes 11 and 12 are arranged in the land section 3d. In the illustrated example, the widthwise sipe 11 has a bent shape, but is not limited to this case. The widthwise sipe 11 extends from the circumferential main groove 2d, bends, and terminates within the land section 3d. In the illustrated example, the inclination angle of the widthwise sipe 12 with respect to the tire width direction is approximately the same as the inclination angle of the branch groove 10b with respect to the tire width direction, but is not limited to this case. In the illustrated example, the widthwise sipe 11 extends in opposite directions from the widthwise sipe 7 in the tire circumferential direction.

[0027] The sub-groove 6a of the resonator 6 located on the land portion 3b is positioned to extend in one direction relative to the branch groove 6b in the tire circumferential direction, and the sub-groove 10a of the resonator 10 located on the land portion 3d is positioned to extend in the other direction relative to the branch groove 10b in the tire circumferential direction (in the illustrated example, the sub-groove 6a also has a portion that extends in the other direction relative to the branch groove 6b in the tire circumferential direction, but the majority of the groove area extends in one direction relative to the branch groove 6b in the tire circumferential direction). In addition, in the illustrated example, a portion of the widthwise sipe 7, the widthwise sipe 9, and the branch groove 10b are located approximately on the extension line. Also, in the illustrated example, the branch groove 6b, the widthwise sipe 9, and the widthwise sipe 12 are located approximately on the extension line.

[0028] The land portion 3e is the outermost land portion in the tire width direction of the other half in the tire width direction (which can be the inner side when mounted on a vehicle). Multiple widthwise sipes 13 extending from the tread edge TE to the circumferential main groove 2d and multiple widthwise sipes 14 extending from the tread edge TE and terminating within the land portion 3e are alternately arranged in the tire circumferential direction. The widthwise sipes 13 and 14 can extend without inclination with respect to the tire width direction, or they can extend at an inclination with respect to the tire width direction (for example, at an inclination angle of 5 to 25°). In the illustrated example, one widthwise sipe 13 and 14 are arranged at one pitch each, but this is not the only example.

[0029] The width (opening width) of the sipes 4, 5, 7, 8, 9, 11, 12, 13, and 14 in the width direction is not particularly limited, but can be 1 mm or less. Also, the depth (maximum depth) of the sipes 4, 5, 7, 8, 9, 11, 12, 13, and 14 in the width direction is not particularly limited, but can be 3 to 8 mm.

[0030] Here, the overlap amount, which is the tire circumferential length when the sub-grooves 6a and 10a of the resonators 6 and 10 formed on different land sections 2b and 2d are projected in the tire width direction, is 50% or less of the tire circumferential length of at least one of the sub-grooves 6a (10a). The following describes the effects and advantages of the pneumatic tire of this embodiment.

[0031] In this embodiment, the overlap amount, which is the tire circumferential length when the sub-grooves 6a and 10a of the resonators 6 and 10 formed on different land sections 2b and 2d are projected in the tire width direction, is 50% or less of the tire circumferential length of at least one of the sub-grooves 6a (10a). Therefore, the groove area (by the resonators 6 and 10) on land sections 3b and 3d can be reduced, thereby improving the rigidity of the land sections 3b and 3d and, consequently, the entire tread surface 1. Furthermore, with this configuration, there are no areas where the groove area becomes extremely large and the rigidity decreases, so the rigidity balance of the entire land sections 3b and 3d and, consequently, the entire tread surface 1 can be made uniform. Furthermore, the arrangement of the resonators 6(10) can itself become a source of pattern noise and pumping noise. However, in this embodiment, the overlap amount is set to 50% or less of the tire circumferential length of at least one of the sub-grooves 6a(10a), thus reducing the sources of such noise and thereby reducing pattern noise and pumping noise. Furthermore, the air column resonance noise generated in the circumferential main grooves 2b and 2c can be reduced by optimizing the design of the shape, groove width, groove depth, and groove volume of the secondary grooves 6a (10a) and branch grooves 6b (10b) according to the specifications of the circumferential main grooves 2b and 2c. Therefore, even if the number density of resonators 6 (10) is reduced, a significant decrease in performance can be avoided.

[0032] The overlap amount is preferably 50% or less of the tire circumferential length of both sub-grooves 6a and 10a. This is because it is possible to further ensure the rigidity of the land sections 3b and 3d while making the overall rigidity balance of the land sections 3b and 3d uniform.

[0033] For similar reasons, the overlap amount is more preferably 40% or less of the tire circumferential length of at least one of the sub-grooves 6a (10a), and even more preferably 30% or less. For similar reasons, the overlap amount is more preferably 40% or less of the tire circumferential length of both sub-grooves 6a and 10a, and even more preferably 30% or less. Furthermore, the lower limit of the overlap amount can be 0, and is therefore not particularly limited.

[0034] Preferably, the sum of the circumferential lengths of the tire circumferential regions where no resonators 6(10) are located in any of the land areas (3a~3e) is 40~60% of the total circumference of the tire. By making the area without such grooves more than 40% of the tire's circumference, it is possible to further ensure the rigidity of the land sections 3b and 3d while also making the overall rigidity balance of the land sections 3b and 3d uniform. On the other hand, by making the area less than 60% of the tire's circumference, it is possible to arrange a certain number of resonators 6 (10) to effectively reduce the air column resonance noise generated in the circumferential main grooves 2b and 2c.

[0035] Preferably, the sub-groove 6a of the resonator 6 located on one of the land sections 3b of the different land sections is positioned to extend in one direction in the tire circumferential direction relative to the branch groove 6b, and the sub-groove 10a of the resonator 10 located on the other land section 3d of the different land sections is positioned to extend in the other direction in the tire circumferential direction relative to the branch groove 10b. Furthermore, this allows for a balance in the rigidity of the land sections 3b and 3d.

[0036] From the viewpoint of ensuring the rigidity of the land portion 3, it is preferable that at least one of the land portions 3 be rib-shaped land portions (land portions that are not completely separated in the circumferential direction of the tire by widthwise grooves (opening width of 2 mm or more) that extend in the tire width direction), and it is more preferable that all of the land portions 3 are rib-shaped land portions, as in this example. Furthermore, it is preferable that at least one of the land portions 3 do not have widthwise grooves themselves, and it is more preferable that all of the land portions 3 do not have widthwise grooves themselves, as in this example.

[0037] As shown in the figure, the tread pattern may have so-called pitch variations, in which case, it is preferable that the overlap amount at any circumferential position is 50% or less of the tire circumferential length of at least one of the sub-grooves.

[0038] Figure 2 shows an example of the arrangement of a communication device. The tire may be equipped with an RF tag as a communication device 100. The RF tag comprises an IC chip and an antenna. The RF tag may be positioned, for example, sandwiched between multiple identical or different components that make up the tire. This makes it easier to attach the RF tag during tire production and improves the productivity of tires equipped with RF tags. In this example, the RF tag may be positioned, for example, sandwiched between a bead filler and other components adjacent to the bead filler. The RF tag may be embedded within one of the components that make up the tire. This reduces the load on the RF tag compared to when it is sandwiched between multiple components that make up the tire. This improves the durability of the RF tag. In this example, the RF tag may be embedded within a rubber component such as the tread rubber or side rubber. It is preferable that RF tags are not placed at locations that are boundaries between members with different rigidities in the peripheral length direction, which is the direction along the outer surface of the tire in a cross-sectional view in the tire width direction. By doing so, RF tags are not placed at locations where strain is likely to concentrate due to rigidity differences. Therefore, the load applied to RF tags can be reduced. This improves the durability of RF tags. In this example, it is preferable that RF tags are not placed at locations that are boundaries between, for example, the end of the carcass and a member adjacent to the end of this carcass (e.g., side rubber) in a cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. A tire may have only one RF tag, or it may have two or more RF tags. Here, RF tags are used as an example of a communication device, but other communication devices may be used.

[0039] The RF tag may be placed, for example, on the tire tread. In this way, the RF tag will not be damaged by a tire side cut. The RF tag may be positioned, for example, in the center of the tread in the tire width direction. The center of the tread is a position where flexing is less likely to concentrate in the tread. This reduces the load on the RF tag, thereby improving its durability. It also suppresses differences in communication with the RF tag from both outer sides of the tire in the tire width direction. In this example, the RF tag may be positioned, for example, within a range of half the tread width centered on the tire equator in the tire width direction. The RF tag may be placed, for example, at the tread edge in the tire width direction. If the position of the reader that communicates with the RF tag is predetermined, the RF tag may be placed, for example, at one tread edge closest to this reader. In this example, the RF tag may be placed, for example, within a quarter of the tread width in the tire width direction, with the tread edge as the outer edge.

[0040] The RF tag may be positioned on the inner side of the tire cavity, for example, beyond the carcass, which includes one or more carcass plies that span between the bead portions. This makes the RF tag less susceptible to damage from impacts applied from outside the tire, such as side cuts or nail punctures. As an example, the RF tag may be positioned in close contact with the inner surface of the carcass facing the inner cavity. As another example, if there is another component on the inner side of the tire cavity beyond the carcass, the RF tag may be positioned, for example, between the carcass and the other component located on the inner side of the carcass facing the inner cavity. An example of another component located on the inner side of the tire cavity beyond the carcass is the inner liner that forms the inner surface of the tire. As yet another example, the RF tag may be attached to the inner surface of the tire facing the inner cavity. By configuring the RF tag to be attached to the inner surface of the tire, it becomes easier to attach the RF tag to the tire and to inspect and replace the RF tag. In other words, the ease of attachment and maintenance of the RF tag can be improved. Furthermore, by attaching the RF tag to the inner surface of the tire, it is possible to prevent the RF tag from becoming the core of tire failure, compared to a configuration where the RF tag is embedded inside the tire. Furthermore, if the carcass has multiple carcass plies and there are positions where multiple carcass plies overlap, the RF tag may be placed between the overlapping carcass plies.

[0041] The RF tag may be positioned, for example, on the tire tread, outside the belt, which includes one or more belt plies, in the radial direction of the tire. For example, the RF tag may be positioned outside the belt in the radial direction of the tire, in close contact with the belt. Another example is when a reinforcing belt layer is provided, the RF tag may be positioned outside the reinforcing belt layer in the radial direction of the tire, in close contact with the reinforcing belt layer. Yet another example is when the RF tag is embedded in the tread rubber, outside the belt in the radial direction of the tire. By positioning the RF tag outside the belt in the tire tread, communication with the RF tag from the outside of the tire in the radial direction is less likely to be hindered by the belt. Therefore, communication with the RF tag from the outside of the tire in the radial direction of the tire can be improved. Furthermore, the RF tag may be positioned, for example, in the tire tread area, radially inward from the belt. In this way, the outer side of the RF tag in the radial direction of the tire is covered by the belt, making the RF tag less susceptible to damage from impacts from the tread surface or nail punctures. As an example, the RF tag may be positioned in the tire tread area between the belt and the carcass located radially inward from the belt. Furthermore, if the belt has multiple belt plies, the RF tag may be positioned between any two belt plies on the tire tread. In this way, the outer side of the RF tag in the radial direction of the tire is covered by one or more belt plies, making the RF tag less susceptible to damage from impacts from the tread surface or nail punctures.

[0042] The RF tag may be placed, for example, in the sidewall or bead area of ​​the tire. The RF tag may be placed, for example, in the sidewall or bead area on one side that is closer to the reader that can communicate with the RF tag. This improves the communication between the RF tag and the reader. As an example, the RF tag may be placed between the carcass and the side rubber, or between the tread rubber and the side rubber. The RF tag may be positioned, for example, between the position of the tire's maximum width and the position of the tread surface in the tire's radial direction. This configuration improves communication with the RF tag from the outside of the tire in the tire's radial direction compared to a configuration where the RF tag is positioned inside the position of the tire's maximum width in the tire's radial direction. The RF tag may be positioned, for example, radially inward from the point of maximum tire width. This positioning places the RF tag near the highly rigid bead, thus reducing the load on the RF tag and improving its durability. As another example, the RF tag may be positioned adjacent to the bead core in either the radial or widthwise direction. Strain is less likely to concentrate near the bead core, further reducing the load on the RF tag and improving its durability. In particular, it is preferable that the RF tag be positioned radially inward from the point of maximum tire width, and radially outward from the bead core of the bead portion. This improves the durability of the RF tag, and also makes communication between the RF tag and the reader less likely to be hindered by the bead core, thereby improving the communication performance of the RF tag. Furthermore, if the side rubber is composed of multiple identical or different rubber members adjacent to each other in the radial direction of the tire, the RF tag may be positioned sandwiched between the multiple rubber members that make up the side rubber.

[0043] The RF tag may be positioned sandwiched between the bead filler and a component adjacent to the bead filler. This allows the RF tag to be placed in a location where strain is less likely to concentrate due to the placement of the bead filler. Therefore, the load on the RF tag can be reduced, thereby improving the durability of the RF tag. The RF tag may be positioned, for example, sandwiched between the bead filler and the carcass. The portion of the carcass that sandwiches the RF tag together with the bead filler may be located either on the outside or inside of the tire width direction relative to the bead filler. If the portion of the carcass that sandwiches the RF tag together with the bead filler is located on the outside of the tire width direction relative to the bead filler, the load on the RF tag from impacts and damage from the outside of the tire in the tire width direction can be further reduced. This can further improve the durability of the RF tag. Furthermore, the bead filler may include a portion positioned adjacent to the side rubber. In such a case, the RF tag may be positioned sandwiched between the bead filler and the side rubber. Furthermore, the bead filler may include a portion positioned adjacent to the rubber chafer. In such a case, the RF tag may be positioned sandwiched between the bead filler and the rubber chafer.

[0044] The RF tag may be positioned, for example, sandwiched between a rubber chafer and a side rubber. This allows the RF tag to be placed in a location where strain is less likely to concentrate due to the placement of the rubber chafer. Therefore, the load on the RF tag can be reduced, thereby improving the durability of the RF tag. The RF tag may be positioned, for example, sandwiched between a rubber chafer and a carcass. This reduces the load on the RF tag from impacts and damage from the rim, thereby improving the durability of the RF tag.

[0045] The RF tag may be positioned sandwiched between the wire chafer and another component adjacent to the wire chafer on the inner or outer side in the tire width direction. This arrangement makes it less likely for the RF tag's position to change during tire deformation. Therefore, the load on the RF tag during tire deformation can be reduced, thereby improving the durability of the RF tag. The other component adjacent to the wire chafer on the inner or outer side in the tire width direction may be, for example, a rubber component such as a rubber chafer. Alternatively, the other component adjacent to the wire chafer on the inner or outer side in the tire width direction may be, for example, a carcass.

[0046] A belt reinforcing layer may be further provided on the radially outer side of the belt. For example, the belt reinforcing layer may consist of a cord made of polyethylene terephthalate wound continuously in a spiral shape in the circumferential direction of the tire. Here the cord is 6.9 × 10 -2 The belt is treated with adhesive under a tension of N / tex or higher, and its modulus of elasticity at a load of 29.4N measured at 160°C may be 2.5mN / dtex·% or higher. Furthermore, the belt reinforcement layer may be arranged to cover the entire belt or to cover only the ends of the belt. In addition, the winding density per unit width of the belt reinforcement layer may differ at different positions in the width direction. By doing so, road noise and flat spots can be reduced without reducing high-speed durability.

[0047] This tire may have multiple cushioning recesses arranged along the tire's circumferential direction on the outer surface of the buttress portion, extending over the entire circumferential direction of the tire, and capable of compression deformation in the tire's radial direction. Multiple rows of cushioning recesses arranged circumferentially may be arranged in multiple rows in the tire's radial direction. The rows may be offset from each other by, for example, half a pitch. Here, "buttress portion" refers to the tire's radial region from the contact end to the split point, and "contact end" refers to the outermost point in the tire's width direction of the contact surface that contacts the road surface when a pneumatic tire is mounted on the applicable rim, filled to the specified internal pressure, and subjected to the maximum load. In one example, the cushioning recess may be hexagonal in shape, with a length in the tire's circumferential direction being longer than the length in the tire's radial direction in a plan view of the buttress portion. The cushioning recess may also be truncated hexagonal in shape. [Explanation of symbols]

[0048] 1: Tread surface, 2: Circumferential main groove, 3: Rikube, 4: Widthwise sipes, 5: Widthwise sipes, 6: Resonator, 6a: Minor groove, 6b: Branch groove, 7: Widthwise sipes, 8: Widthwise sipes, 9: Widthwise sipes, 10: Resonator, 10a: Minor groove, 10b: Branch groove, 11: Widthwise sipes, 12: Widthwise sipes, 13: Widthwise sipes, 14: Widthwise sipes, CL: Tire equatorial plane, TE: Tread edge

Claims

1. A pneumatic tire comprising a tread surface having a plurality of land areas, each land area having at least one side in the tire width direction demarcated by a circumferential main groove extending in the tire circumferential direction, and each land area having a plurality of resonators having a secondary groove terminating within the land area and at least one branch groove connecting the secondary groove to the circumferential main groove, A pneumatic tire characterized in that the overlap amount, which is the tire circumferential length when the sub-grooves of the resonators formed in different land portions are projected in the tire width direction, is 50% or less of the tire circumferential length of at least one of the sub-grooves.

2. The pneumatic tire according to claim 1, wherein the overlap amount is 50% or less of the tire circumferential length of both sub-grooves.

3. The pneumatic tire according to claim 1 or 2, wherein the sum of the circumferential lengths of the tire in the tire circumferential regions where the resonators are not located in any of the land portions is 40 to 60% of the total circumference of the tire.

4. The pneumatic tire according to claim 1 or 2, wherein the secondary groove of the resonator located on one of the different land portions is arranged to extend in one direction in the tire circumferential direction relative to the branch groove, and the secondary groove of the resonator located on the other land portion of the different land portions is arranged to extend in the other direction in the tire circumferential direction relative to the branch groove.

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