A tire 1 includes a communication device 10 embedded inside a tire side portion 1d and a plurality of turbulence-generating projections F projecting from a tire outer surface 1ds of the tire side portion, extending along the tire radial direction, and arranged at intervals in the tire circumferential direction. The communication device overlaps at least one of an inter-projection recess G between adjacent turbulence-generating projections and the turbulence-generating projection F in a projected plane of the tire side portion in the tire width direction.

TECHNICAL FIELD

The present disclosure relates to a tire.

The present application claims priority to Japanese Patent Application No. 2021-148904 filed on Sep. 13, 2021, the entire contents of which are incorporated herein by reference.

BACKGROUND

A tire that has a communication device (such as an RF tag) embedded inside the tire is known (Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

However, the conventional tire described above has room for improvement in the durability of the communication device.

The present disclosure aims to provide a tire that can improve the durability of a communication device.

Solution to Problem

A tire of the present disclosure includes:a communication device embedded inside a tire side portion; anda plurality of turbulence-generating projections projecting from a tire outer surface of the tire side portion, extending along a tire radial direction, and arranged at intervals in a tire circumferential direction, whereinthe communication device overlaps at least one of an inter-projection recess between adjacent turbulence-generating projections and the turbulence-generating projection in a projected plane of the tire side portion in a tire width direction.

Advantageous Effect

According to the present disclosure, a tire that can improve the durability of a communication device can be provided.

DETAILED DESCRIPTION

A tire according to the present disclosure can be suitably used as any type of pneumatic tire, such as a passenger vehicle pneumatic tire and a truck/bus pneumatic tire.

Embodiments of a tire according to the present disclosure are described below with reference to the drawings.

Members and components that are common across drawings are labeled with the same reference signs. In some of the drawings, the tire width direction is indicated by the reference sign “TW”, the tire radial direction by the reference sign “RD”, and the tire circumferential direction by the reference sign “CD”. In the present description, the side closer to the tire inner cavity is referred to as the “tire inner side”, and the side farther from the tire inner cavity as the “tire outer side”.

FIGS.1and2are diagrams illustrating a tire1according to a first embodiment of the present disclosure.FIG.1is a side view of a portion of the tire side portion of the tire according to the first embodiment of the present disclosure, as viewed from the outside in the tire width direction.FIG.2is a cross-sectional view, in the tire width direction, illustrating a portion of the tire inFIG.1(specifically, a portion on one side with respect to the tire equatorial plane CL) by a cross-section along the A-A line inFIG.1.FIG.6is a cross-sectional view, in the tire width direction, illustrating a portion of a tire according to a second embodiment of the present disclosure (specifically, a portion on one side with respect to the tire equatorial plane CL).

The tire1of the embodiment inFIGS.1and2is configured as a passenger vehicle pneumatic tire. The tire1of the embodiment inFIG.6is configured as a truck/bus pneumatic tire. For the sake of convenience, these embodiments will be described together below.

The tire1of any embodiment of the present disclosure may be configured as any type of tire.

The tire1includes a tire main body1M and a communication device10. The tire main body1M corresponds to the portion of the tire1other than the communication device10.

Unless otherwise specified, the positional relationships, dimensions, and the like of elements are assumed below to be measured in a reference state in which the tire1is mounted on an applicable rim and filled to a prescribed internal pressure, with no load applied. The width in the tire width direction of the contact patch in contact with the road surface when the tire1is mounted on the applicable rim and filled to the prescribed internal pressure, with the maximum load applied, is referred to as the ground contact width of the tire, and the edges in the tire width direction of the contact patch are referred to as the ground contact edges.

In the present description, the “applicable rim” refers to a standard rim of an applicable size, such as the Measuring Rim in the STANDARDS MANUAL of the European Tyre and Rim Technological Organisation (ETRTO) in Europe or the Design Rim in the YEAR BOOK of the Tire and Rim Association, Inc. (TRA) in the USA, that is described, or will be described in the future, in industrial standards effective in the region where the pneumatic tire is manufactured and used, such as the JATMA YEAR BOOK published by the Japan Automobile Tyre Manufacturers Association (JATMA) in Japan, the STANDARDS MANUAL of the ETRTO, and the YEAR BOOK of the TRA. In the case of a size not specified in the aforementioned industrial standards, the “rim” refers to a rim whose width corresponds to the bead width of the pneumatic tire. The “applicable rim” includes sizes that will be described in the future in the aforementioned industrial standards, in addition to current sizes. Examples of the “sizes that could be described in the future” include the sizes described under “FUTURE DEVELOPMENTS” in the ETRTO STANDARDS MANUAL 2013.

In the present specification, the “prescribed internal pressure” refers to the air pressure (maximum air pressure) corresponding to the maximum load capability of a single wheel for the applicable size/ply rating in industrial standards, such as the aforementioned JATMA YEAR BOOK. In the case of a size not described in the aforementioned industrial standards, the “prescribed internal pressure” refers to the air pressure (maximum air pressure) corresponding to the maximum load capability prescribed for each vehicle on which the tire is mounted. In the present specification, the “maximum load” refers to the load corresponding to the maximum load capability for a tire of the applicable size described in the aforementioned industrial standards. In the case of a size not described in the aforementioned industrial standards, the “maximum load” refers to the load corresponding to the maximum load capability prescribed for each vehicle on which the tire is mounted.

First, the tire main body1M will be described.

As illustrated inFIG.2,FIG.6, and the like, in each of the embodiments in the present description, the tire main body1M includes a tread portion la, a pair of sidewall portions1bextending inward in the tire radial direction from both tread widthwise ends of the tread portion1a, and a pair of bead portions1cprovided at the respective tire radial inner ends of the sidewall portions1b.The tread portion1ais the tire widthwise portion between the pair of ground edges in the tire main body1M. The bead portion1cis configured to contact the rim on the inner side in the tire radial direction and the outer side in the tire width direction when the tire1is mounted on the rim.

The tire main body1M has a pair of tire side portions1dextending inward in the tire radial direction from both tire widthwise ends of the tread portion1a. The tire side portion1dis formed by the tire sidewall portion1band the bead portion1c.The surface on the tire outer side of the tire side portion1dis referred to in the present description as the “tire outer surface1dsof the tire side portion1d”.

The tire main body1M also includes a pair of bead cores4a,a pair of bead fillers4b,a carcass5, a belt6, a tread rubber7, a side rubber8, and an inner liner9.

Each bead core4ais embedded in the corresponding bead portion1c. The bead core4aincludes a plurality of bead wires that are coated by rubber. The bead wires are preferably made of metal (such as steel). The bead wires can, for example, be made of monofilaments or twisted wires. The bead wires may also be made of organic fibers or carbon fibers.

Each bead filler4bis positioned farther outward in the tire radial direction than the corresponding bead core4a.The bead filler4btapers while extending outward in the tire radial direction. The bead filler4bis, for example, made of rubber.

Bead fillers are sometimes referred to as “stiffeners”.

As illustrated inFIG.6, in a case in which the tire main body1M (and thus the tire1) is configured as a truck/bus pneumatic tire, the bead filler4bmay be formed by a plurality of (in the example inFIG.6, two) bead filler portions4b1and4b2. These bead filler portions4b1,4b2may, for example, differ in hardness. These bead filler portions4b1,4b2may, for example, be arranged (stacked) along the tire radial direction.

The carcass5spans the pair of bead cores4aand extends toroidally. The carcass5is configured by one or more carcass plies5a.Each carcass ply5aincludes one or more carcass cords and a coating rubber covering the carcass cords. The carcass cords can be formed from monofilaments or twisted wires.

The carcass cords may be made of organic fibers composed of polyester, nylon, rayon, aramid, or the like, or may be made of metal (such as steel). In a case in which the tire1is configured as a truck/bus pneumatic tire, the carcass cords are preferably made of metal (such as steel). In a case in which the tire1is configured as a passenger vehicle pneumatic tire, the carcass cords are preferably made of organic fibers, such as polyester, nylon, rayon, aramid, or the like.

The carcass ply5aincludes a ply main body5M located between the pair of bead cores4a.The carcass ply5amay further include a ply turn-up portion5T that is turned up, from both ends of the ply main body5M, around the bead core4afrom the inside to the outside in the tire width direction. The carcass ply5aneed not include the ply turn-up portion5T, however. The carcass5preferably has a radial structure but may also have a bias structure.

The belt6is disposed farther outward in the tire radial direction than a crown portion of the carcass5. The belt6includes one or more belt layers6a.Each belt layer6aincludes one or more belt cords and a coating rubber covering the belt cords. The belt cords can be formed from monofilaments or twisted wires. The belt cords may be made of metal (such as steel) or may be made of organic fibers composed of polyester, nylon, rayon, aramid, or the like.

The tread rubber7is located on the tire radial outer side of the belt6in the tread portion1a. The tread rubber7forms the tread surface, which is the tire radial outer surface of the tread portion1a. A tread pattern is formed on the tread surface.

The side rubber8is located on the tire widthwise outer side of the carcass5in the sidewall portion1b.The side rubber8forms the tire widthwise outer surface of the sidewall portion1b.The side rubber8is integrally formed with the tread rubber7.

The inner liner9is disposed on the tire inner side of the carcass5and may, for example, be laminated onto the tire inner side of the carcass5. The inner liner9is, for example, configured by a butyl-based rubber having low air permeability. Examples of butyl-based rubber include butyl rubber and butyl halide rubber, which is a derivative thereof. The inner liner9is not limited to butyl-based rubber and can be configured by other rubber compositions, resins, or elastomers.

As illustrated inFIG.6, in a case in which the tire main body1M (and thus the tire1) is configured as a truck/bus pneumatic tire, the tire main body1M may include a reinforcement member3around the bead core4a.The reinforcement member3may be disposed on the opposite side of the bead core4afrom the carcass5, as in the example inFIG.6. The reinforcement member3includes one or more (in the example inFIG.6, three) reinforcement plies3a.Each reinforcement ply3acontains a reinforcement cord. The reinforcement cord may be made of metal (such as steel) or may be made of organic fibers composed of polyester, nylon, rayon, aramid, or the like.

In each of the embodiments in the present description, as illustrated inFIGS.1,2, and6, the tire main body1M includes a plurality of turbulence-generating projections F projecting from the tire outer surface1dsof the tire side portion1d,extending along the tire radial direction, and arranged at intervals in the tire circumferential direction. An inter-projection recess G that is recessed inward in the tire width direction is defined between adjacent turbulence-generating projections F.

Here, with reference toFIG.5, the effect of the turbulence-generating projections F will be described. As illustrated inFIG.5, as the tire1rotates, the air flow S1in contact with the tire outer surface1dsof the tire side portion1dwhere the turbulence-generating projection F is not formed is detached from the tire outer surface1dsby the turbulence-generating projection F and overcomes the turbulence-generating projection F. On the back side of the turbulence-generating projection F, a portion (region) S2is created in which the air flow is stagnant.

The air flow S1then reattaches to the tire outer surface1dsbetween the back side and the next turbulence-generating projection F and is detached again at the next turbulence-generating projection F. At this time, a portion (region) S3is created in which the air flow is stagnant between the air flow S1and the next turbulence-generating projection F and the like. Here, increasing the velocity gradient (speed) over the region in contact with the turbulence S1is considered advantageous for increasing the cooling effect. In other words, provision of the turbulence-generating projection F on the tire outer surface1dsof the tire side portion1dgenerates the air flow S1with a high flow rate and the stagnant portions S2, S3and promotes the generation of turbulence on the tire outer surface1dsof the tire side portion1d,thereby enhancing the cooling effect of the tire side portion1d.

Next, the communication device10will be described.

The configuration of the communication device10is not limited, provided that the communication device10is configured to communicate wirelessly with a predetermined external device (such as a reader or a reader/writer) located external to the tire1.

The communication device10preferably includes an RF tag. RF tags are also referred to as “RFID tags”. The RF tag is preferably configured as a passive type but may be configured as an active type.

Instead of or in addition to an RF tag, the communication device10may include an acceleration sensor that detects the acceleration of the tire1, an internal pressure sensor that detects the internal pressure of the tire1, or the like.

FIGS.3and4illustrate an example of the communication device10. In the present example, the communication device10has an RF tag. In the present example, the communication device10includes an RF tag10eand a cover10f.The RF tag10eincludes an IC chip10cand an antenna unit10b. The RF tag10eis configured as a passive type.

The IC chip10coperates by an induced electromotive force generated by radio waves received by the antenna unit10b,for example. The IC chip10chas a controller and a memory, for example.

The memory may store any information. For example, the memory may store identification information for the tire1. The identification information for the tire1is unique identification information for the tire1capable of identifying each tire individually, such as the manufacturer of the tire1, the manufacturing plant, the date of manufacture, and the like. The memory may also store tire history information such as the running distance of the tire, the number of instances of sudden braking, the number of instances of sudden starts, and the number of instances of sudden turns. Sensors that detect the tire internal temperature, tire internal pressure, tire acceleration, and the like may be provided in the tire inner cavity, for example, and the memory may store detection information detected by these sensors. In this case, the RF tag10ecan acquire the detection information from the sensors by wirelessly communicating with the sensors through the antenna unit10b.

The controller is configured to be capable of reading information from the memory.

The antenna unit10bhas a pair of antennas10b1,10b2. The antennas10b1,10b2are connected to respective ends located on opposite sides of each other in the IC chip10c.The antenna unit10bis configured to be capable of transmission and reception to and from the aforementioned predetermined external device that is external to the tire1. In the example inFIGS.3and4, each antenna10b1,10b2extends in a straight line, but each antenna10b1,10b2may extend to form any shape, such as a wave shape.

The cover10fcovers the entire RF tag10e.The cover10fis formed from rubber or resin, for example.

In the present example, the cover10fhas a pair of sheet-like covering members10f1and10f2. The pair of covering members10f1,10f2overlap with the RF tag10esandwiched between them. The pair of covering members10f1,10f2are preferably fixed to each other by adhesion or the like.

The cover10fmay, however, be configured by a single member.

In the present example, the cover10fhas a rectangular shape in plan view, but the cover10fmay have any shape in plan view.

The communication device10need not have the cover10f,i.e., the communication device10may be configured only by the RF tag10e.

The communication device10thus configured is capable of receiving, via the antenna unit10b,information transmitted through a radio wave or magnetic field from the aforementioned predetermined external device. Due to rectification (in the case of radio waves) or resonance (in the case of magnetic fields), electricity is generated in the antenna unit10bof the communication device10, and the memory and controller of the IC chip10cperform predetermined operations. For example, the controller reads the information in the memory and returns (transmits) the information to the aforementioned predetermined external device from the antenna10bthrough a radio wave or magnetic field. The aforementioned predetermined external device receives the radio wave or magnetic field from the communication device10. By retrieving the received information, the aforementioned predetermined external device can acquire the information stored in the memory of the IC chip10cof the communication device10.

The communication device10may, however, have any configuration other than that of the present example.

The communication device10may have a longitudinal direction LD, a transverse direction SD, and a thickness direction TD. The longitudinal direction LD, the transverse direction SD, and the thickness direction TD are perpendicular to each other.

As illustrated inFIGS.3and4, in a case in which the communication device10has the RF tag10e,the longitudinal direction LD of the communication device10is parallel to the extending direction of the antenna unit10b.In a case in which each of the antennas10b1,10b2of the antenna unit10bis wave-shaped, the extending direction of the antenna unit10brefers to the extending direction of the amplitude centerline of the wave shape formed by each of the antennas10b1,10b2. In the communication device10, the thickness direction TD of the communication device10refers to the thickness direction of the cover10fin a case in which the communication device10has the cover10fand refers to the thickness direction of the IC chip10cin a case in which the communication device10does not have the cover10f.

The length of the RF tag10ein the longitudinal direction LD is, for example, preferably 20 mm or more, or 50 mm or more. The length of the RF tag10ein the longitudinal direction LD is, for example, preferably 100 mm or less, or 70 mm or less.

The length of the RF tag10ein the transverse direction SD is, for example, preferably 10 mm or less, or 8 mm or less.

The length of the RF tag10ein the thickness direction TD is, for example, preferably 5 mm or less, or 2 mm or less.

In a case in which the communication device10has the cover10f,the length of the communication device10in the longitudinal direction LD is, for example, preferably 30 mm or more, or 60 mm or more. The length of the RF tag10ein the longitudinal direction LD is, for example, preferably 110 mm or less, or 80 mm or less.

In a case in which the communication device10has the cover10f,the length of the communication device10in the transverse direction SD is, for example, preferably 20 mm or less, or 15 mm or less.

In a case in which the communication device10has the cover10f,the thickness of the communication device10in the thickness direction TD is, for example, preferably 6 mm or less, or 3 mm or less.

The thickness of each of the covering members10f1,10f2of the cover10fis, for example, preferably 0.5 mm or more. The thickness of each of the covering members10f1,10f2of the cover10fis, for example, preferably 1 mm or less.

In each of the embodiments in the present description, the entire communication device10is embedded inside the tire side portion1dof the tire main body1M, as illustrated inFIGS.1,2, and6. The communication device10is embedded in a portion of the tire side portion1dof the tire body1M that is farther outward in the tire width direction than the carcass5.

The communication device10overlaps at least one of an inter-projection recess G between adjacent turbulence-generating projections F and a turbulence-generating projection F (in the example inFIG.1, an inter-projection recess G) in a projected plane (FIG.1) of the tire side portion1din the tire width direction. Here, the “projected plane of the tire side portion1din the tire width direction” is the projected plane when the tire side portion1dis viewed as projected in the tire width direction, as illustrated inFIG.1.

The communication device10is oriented so that the thickness direction TD of the communication device10is substantially aligned with the tire width direction (FIGS.2and6).

During production of the tire1, a raw tire forming the tire main body1M and the communication device10are housed inside a mold for forming a tire and are vulcanized.

The effects of each embodiment in the present description are now explained.

First, as described above, in each of the embodiments in the present description, the communication device10is embedded inside the tire side portion1d,as illustrated inFIGS.1,2, and6. Here, in general, metal may weaken the radio waves between the communication device10and the aforementioned predetermined external device (such as a reader or a reader/writer), thereby degrading the communication performance between the communication device10and the aforementioned predetermined external device. This may in turn reduce the communication distance between the communication device10and the aforementioned predetermined external device. On the other hand, in the tire main body1M, metal (such as steel) can be used in the carcass5, the belt6, the bead core4a,the reinforcement member3, and the like. In general, the tire side portion1dtends to have less metal than the tread portion1a. Therefore, arrangement of the communication device10in the tire side portion1dcan improve the communication performance and lengthen the communication distance between the communication device10and the aforementioned predetermined external device as compared to a case in which the communication device10is arranged in the tread portion1a.

As described above, in each of the embodiments in the present description, the tire main body1M includes a plurality of turbulence-generating projections F, the communication device10is embedded inside the tire side portion1dof the tire main body1M, and the communication device10overlaps at least one of an inter-projection recess G between adjacent turbulence-generating projections F and a turbulence-generating projection F in a projected plane (FIG.1) of the tire side portion1din the tire width direction, as illustrated inFIGS.1,2, and6. As a result, heat generated from the communication device10can be effectively dissipated by the turbulence-generating projections F, thereby suppressing thermal aging of the communication device10, which in turn improves the durability of the communication device10. In addition, since the turbulence-generating projections F disperse the strain of the tire side portion1dduring rolling and the like of the tire1, the load on the communication device10can be reduced, thereby improving the durability of the communication device10.

In each of the embodiments in the present description, the communication device10is preferably entirely located within the inter-projection recess G in the projected plane (FIG.1) of the tire side portion1din the tire width direction, as in the example inFIG.1. This allows the impact (and thus the damage) from an obstacle to be received by the turbulence-generating projections F when the tire side portion1dcollides with an external obstacle and thus more reliably protects the communication device10, which is located at the position corresponding to the inter-projection recess G, from damage. In this case, the gauge of the side rubber8covering the tire widthwise outer side of the communication device10is thin, yielding a corresponding improvement in the communication performance. In other words, carbon is included in the side rubber8, and in general, carbon may weaken the radio waves between the communication device10and the aforementioned predetermined external device (such as a reader or a reader/writer), thereby degrading the communication performance between the communication device10and the aforementioned predetermined external device. This may in turn reduce the communication distance between the communication device10and the aforementioned predetermined external device. A thin gauge for the side rubber8covering the communication device10therefore leads to improved communication performance.

In each of the embodiments in the present description, the facing direction (orientation) of the communication device10is arbitrary, but from the perspective of durability and the like of the communication device10, the communication device10is preferably oriented so that the longitudinal direction LD of the communication device10is substantially aligned with the tire circumferential direction, as in the example inFIG.1. However, the communication device10may also be oriented so that the transverse direction SD of the communication device10is substantially aligned with the tire circumferential direction.

In each of the embodiments in the present description, the communication device10is preferably arranged in the sidewall portion1b,as in each of the embodiments inFIGS.2and6. In general, the sidewall portion1btends to have less metal than the bead portion1c.Therefore, arrangement of the communication device10in the sidewall portion1bcan improve the communication performance and lengthen the communication distance between the communication device10and the aforementioned predetermined external device as compared to a case in which the communication device10is arranged in the bead portion1c.

In each of the embodiments in the present description, in a case in which the tire1is configured as a passenger vehicle pneumatic tire (FIG.2), the tire radial outer end10uof the communication device10(more preferably, the entire communication device10) is preferably farther outward in the tire radial direction than the tire radial outer end of the bead core4a,more preferably farther outward in the tire radial direction than the tire radial center of the bead filler4b.For example, the tire radial outer end10uis preferably farther outward in the tire radial direction than a tire radial outer end4buof the bead filler4b.

In each of the embodiments in the present description, in a case in which the tire1is configured as a passenger vehicle pneumatic tire (FIG.2), and the communication device10is arranged in the sidewall portion1bas described above, the tire radial outer end10uof the communication device10is preferably located farther inward in the tire radial direction than the tire radial outer end5eof the ply turn-up portion5T of the carcass5, as in the example inFIG.2. This can improve the communication performance and increase the communication distance between the communication device10and the aforementioned predetermined external device, while enabling arrangement of the communication device10in a portion of the tire main body1M that undergoes relatively little distortion during rolling and the like of the tire1, thereby improving the durability of the communication device10and hence the durability of the tire1.

The tire radial distance between the tire radial outer end10uof the communication device10and the tire radial outer end5eof the ply turn-up portion5T of the carcass5is preferably 3 mm to 30 mm, more preferably 5 mm to 15 mm.

In each of the embodiments in the present description, in a case in which the tire1is configured as a passenger vehicle pneumatic tire (FIG.2), the tire radial outer end5eof the ply turn-up portion5T of the carcass5is preferably located farther outward in the tire radial direction than the tire radial outer end4buof the bead filler4b,as in the example inFIG.2. The tire radial outer end5eof the ply turn-up portion5T of the carcass5may, however, be located at the same tire radial position as the tire radial outer end of the bead filler4b,or farther inward in the tire radial direction.

In each of the embodiments in the present description, in a case in which the tire1is configured as a passenger vehicle pneumatic tire (FIG.2), the tire radial outer end5eof the ply turn-up portion5T of the carcass5may be located farther outward in the tire radial direction than the tire maximum width position of the tire main body1M, at the same tire radial position as the tire maximum width position of the tire main body1M, or farther inward in the tire radial direction than the tire maximum width position of the tire main body1M. Here, the “tire maximum width position of the tire main body1M” is the position in the tire radial direction at which the tire main body1M has the maximum dimension in the tire width direction.

In each of the embodiments in the present description, in a case in which the tire1is configured as a passenger vehicle pneumatic tire (FIG.2), the communication device10is preferably in contact with the tire widthwise outer surface of the carcass5and is more preferably in contact with the tire widthwise outer surface of the ply turn-up portion5T of the carcass5, as in the example inFIG.2.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial center10mof the communication device10(more preferably, the entire communication device10) is preferably farther outward in the tire radial direction than the tire radial outer end of the bead core4a.This can improve the communication performance and lengthen the communication distance between the communication device10and the aforementioned predetermined external device.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial center10mof the communication device10(more preferably, the entire communication device10) is preferably farther outward in the tire radial direction than the tire radial outer end5eof the ply turn-up portion5T of the carcass5. This can improve the communication performance and increase the communication distance between the communication device10and the aforementioned predetermined external device, while enabling arrangement of the communication device10in a portion of the tire main body1M that undergoes relatively little distortion during rolling and the like of the tire1, thereby improving the durability of the communication device10and hence the durability of the tire1.

Here, the “tire radial outer end5eof the ply turn-up portion5T of the carcass5” refers to the tire radial outer end that is farthest outward in the tire radial direction among the tire radial outer ends of the ply turn-up portions5T of the carcass plies5aof the carcass5.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial center10mof the communication device10(more preferably, the entire communication device10) is preferably farther outward in the tire radial direction than a tire radial outer end3uof the reinforcement member3. This can improve the communication performance and increase the communication distance between the communication device10and the aforementioned predetermined external device, while enabling arrangement of the communication device10in a portion of the tire main body1M that undergoes relatively little distortion during rolling and the like of the tire1, thereby improving the durability of the communication device10and hence the durability of the tire1.

Here, the “tire radial outer end3uof the reinforcement member3” refers to the tire radial outer end that is farthest outward in the tire radial direction among the tire radial outer ends of the reinforcement plies3aof the reinforcement member3.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial center10mof the communication device10(more preferably, the entire communication device10) is preferably farther inward in the tire radial direction than the tire radial outer end4buof the bead filler4b.This can improve the communication performance and increase the communication distance between the communication device10and the aforementioned predetermined external device, while enabling arrangement of the communication device10in a portion of the tire main body1M that undergoes relatively little distortion during rolling and the like of the tire1, thereby improving the durability of the communication device10and hence the durability of the tire1. The tire radial distance between the tire radial center10mof the communication device10and the tire radial outer end4buof the bead filler4bis preferably 1 mm to 30 mm, more preferably 5 mm to 15 mm.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial outer end5eof the ply turn-up portion5T of the carcass5is preferably located farther inward in the tire radial direction than the tire radial outer end4buof the bead filler4b,but the tire radial outer end5eof the ply turn-up portion5T of the carcass5may be located at the same tire radial position as the tire radial outer end4buof the bead filler4bor farther outward in the tire radial direction.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial outer end3uof the reinforcement member3is preferably located farther inward in the tire radial direction than the tire radial outer end4buof the bead filler4b,but the tire radial outer end3uof the reinforcement member3may be located at the same tire radial position as the tire radial outer end4buof the bead filler4bor farther outward in the tire radial direction.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial outer end5eof the ply turn-up portion5T of the carcass5may be located farther inward in the tire radial direction than the tire maximum width position of the tire main body1M, as in the example inFIG.6, at the same tire radial position as the tire maximum width position of the tire main body1M, or farther outward in the tire radial direction than the tire maximum width position of the tire main body1M.

Here, the “tire maximum width position of the tire main body1M” is the position in the tire radial direction at which the tire main body1M has the maximum dimension in the tire width direction.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial outer end3uof the reinforcement member3may be located farther inward in the tire radial direction than the tire maximum width position of the tire main body1M, as in the example inFIG.6, at the same tire radial position as the tire maximum width position of the tire main body1M, or farther outward in the tire radial direction than the tire maximum width position of the tire main body1M.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the tire radial center10mof the communication device10(more preferably, the entire communication device10) is preferably located farther inward in the tire radial direction than the tire maximum width position of the tire main body1M. This can improve the communication performance and increase the communication distance between the communication device10and the aforementioned predetermined external device, while enabling arrangement of the communication device10in a portion of the tire main body1M that undergoes relatively little distortion during rolling and the like of the tire1, thereby improving the durability of the communication device10and hence the durability of the tire1.

In each of the embodiments in the present description, in a case in which the tire1is configured as a truck/bus pneumatic tire (FIG.6), the communication device10is preferably in contact with the tire widthwise outer surface of the bead filler4b,as in the example inFIG.6.

In each of the embodiments in the present description, the maximum width of the turbulence-generating projection F in the tire circumferential direction is preferably 4.7 mm to 7.1 mm.

This can further improve the durability of the communication device10.

In each of the embodiments in the present description, the length of the turbulence-generating projection F in the tire radial direction is preferably 8 mm to 30 mm.

This can further improve the durability of the communication device10.

In each of the embodiments in the present description, the maximum distance between adjacent turbulence-generating projections F in the tire circumferential direction (i.e., the maximum length of the inter-projection recess G in the tire circumferential direction) is preferably 10 mm to 25 mm.

This can further improve the durability of the communication device10.

Variations of the turbulence-generating projection F are described below with reference toFIGS.7to21.

FIGS.7to9are diagrams illustrating a tire1according to a third embodiment of the present disclosure.FIGS.10to12are diagrams illustrating a tire1according to a fourth embodiment of the present disclosure.FIGS.13to15are diagrams illustrating a tire1according to a fifth embodiment of the present disclosure.FIGS.16to17are diagrams illustrating a tire1according to a sixth embodiment of the present disclosure.FIGS.18to21are diagrams illustrating a tire1according to a seventh embodiment of the present disclosure. The configuration of the turbulence-generating projection F differs in each of the embodiments inFIGS.7to21. However, in each of the embodiments inFIGS.7to21, as in the embodiments described above with reference toFIGS.1to6, the tire main body1M includes a plurality of turbulence-generating projections F projecting from the tire outer surface1dsof the tire side portion1d,extending along the tire radial direction, and arranged at intervals in the tire circumferential direction. An inter-projection recess G that is recessed inward in the tire width direction is defined between adjacent turbulence-generating projections F.

InFIGS.7through21, the communication device10is not depicted for the sake of convenience. In each of the embodiments inFIGS.7to21as well, however, the tire1includes the communication device10, which is embedded inside the tire side portion1dof the tire main body1M, and the communication device10overlaps at least one of an inter-projection recess G between adjacent turbulence-generating projections F and a turbulence-generating projection F in a projected plane of the tire side portion1din the tire width direction.

The tire1according to the third embodiment of the present disclosure is described below with reference toFIGS.7to9.

In the tire1of the third embodiment, a plurality of uneven surfaces extending along the tire radial direction while undulating in the tire width direction is formed at the apex of the turbulence-generating projection F.

As illustrated inFIG.7, the tire side portion1dis provided with turbulence-generating projections20(F). The turbulence-generating projection20(F) extends in the tire radial direction and projects outward in the tire width direction. As also illustrated inFIG.7, a plurality (eight in the present embodiment) of the turbulence-generating projections20(F) is arranged close together along the circumferential direction to form one turbulence-generating projection group. Five of these turbulence-generating projection groups are provided at intervals along the circumferential direction.

FIG.8is an enlarged perspective view illustrating the turbulence-generating projection according to the present embodiment, andFIG.9is a front view ofFIG.8from the tire circumferential direction.

As illustrated in these drawings, the turbulence-generating projection20is defined by a bottom wall21provided at the inner end in the tire radial direction RD, a pair of side wall surfaces22,22provided on both sides in the tire circumferential direction CD, and an apex23provided on the tire widthwise outer side.

The side wall surfaces22are flat while extending along the tire radial direction, and the pair of side wall surfaces22,22are arranged at a predetermined distance from each other.

The apex23is formed into an uneven surface24that repeatedly undulates in the tire width direction. One uneven portion25forming part of this uneven surface24has, in greater detail, a substantially triangular cross-sectional shape formed by a first inclined surface (climbing surface)26inclined outward in the tire width direction while extending outward in the tire radial direction (to the top of the paper inFIGS.8and9) and a second inclined surface (descending surface)27inclined inward in the tire width direction while extending outward in the tire radial direction (to the top of the paper inFIGS.8and9). The apex23of the turbulence-generating projection20is formed into the uneven surface24by a plurality of these uneven portions25being successively formed in the tire radial direction on the apex23.

As illustrated inFIG.9, the boundary portion between the second inclined surface27and the first inclined surface26adjacent to the second inclined surface27becomes a valley point28, and the cross-sectional shape of the valley point28is formed to be curved with a small radius of curvature. Similarly, at an apex29where the first inclined surface26transitions to the second inclined surface27, the cross-sectional shape of the apex29is formed to be curved with a small radius of curvature.

The height of the uneven surface24, i.e., the distance along the tire width direction between the apex29and the surface of the tire side portion1d, is H1. On the other hand, the height of the valley point28, i.e., the distance along the tire width direction between the valley point28and the surface of the tire side portion1d,is H2. Here, the undulation height of the uneven surface24is (H1-H2), and the height of the turbulence-generating projection20is H1. The undulation height of the uneven surface24(H1-H2) is preferably 20% to 70% of the height H1of the turbulence-generating projection20.

In the third embodiment, a plurality of the uneven surfaces24extending along the tire radial direction while undulating in the tire width direction is formed at the apex of the turbulence-generating projection20(F).

Therefore, compared to a turbulence-generating projection with a flat apex, the turbulence-generating projection20(F) with an uneven surface24according to the present embodiment has a greater cooling effect on the tire side portion1d,since the generated turbulence S1(FIG.5) is larger. In addition, in the case of a turbulence-generating projection with a flat apex, air accumulated at the apex of the projection in the mold for forming a tire can easily move without resistance when the tire is vulcanized, which may tend to generate bare portions (air pockets). According to the third embodiment, however, it is difficult for air accumulated at the apex of the projection20in the mold for forming a tire to move during tire vulcanization. Bare portions are thus less likely to occur, and even if they do occur, they are less noticeable as a result of the uneven surface24at the apex. The degradation in the appearance due to the bare portions is thus suppressed. To increase turbulence and improve the effect of cooling the tire side portion1d,the number of uneven surfaces is preferably large.

The undulation height of the uneven surface24(H1-H2) is preferably 20% to 70% of the height H1of the turbulence-generating projection20. By thus limiting the undulation height (H1-H2) of the uneven surface24to a predetermined value, the occurrence of bare portions can be further suppressed.

The uneven surface24has the shape of substantially triangular cross-sections continuously arranged in the tire radial direction, which is a relatively simple shape that has the effect of simplifying the structure of the mold for forming a tire.

The tire1according to the fourth embodiment of the present disclosure is described below with reference toFIGS.10to12.

In the tire1of the fourth embodiment, the tire side portion1dincludes a first rigidity portion, in which a first rubber member formed by a rubber member and having a predetermined rigidity is used, and a second rigidity portion, in which a second rubber member having a rigidity higher than the predetermined rigidity is used. The turbulence-generating projections F are only provided in the first rigidity portion.

As illustrated inFIG.11, the tire side portion1dincludes a low-rigidity portion61(first rigidity portion) and a high-rigidity portion62(second rigidity portion). In the low-rigidity portion61, a first rubber member formed by a rubber member and having a predetermined rigidity is used. In the present embodiment, the first rubber member is the portion of the side rubber8of the tire side portion1din the region from the ground edge51, which is located farthest outward in the tire width direction when the tread portion1acontacts the road surface, to the tire radial outer end4buof the bead filler4b(hereinafter referred to as the side rubber portion60A). For example, rubber with a Young's modulus of 5 MPa to 7 MPa (at 25° C.) is used in the side rubber portion60A.

A second rubber member having a higher rigidity than the rigidity of the first rubber member, i.e., than the rigidity of the side rubber portion60A, is used in the high-rigidity portion62. In the present embodiment, the second rubber member is the bead filler4b.For example, rubber with a Young's modulus of 50 MPa to 500 MPa, particularly 110 MPa to 130 MPa (at 25° C.), is preferably used in the bead filler4b.

Here, the temperature dependence of the bead filler4bis greater than the temperature dependence of the side rubber portion60A. The temperature dependence is the property whereby the rigidity of a tire component changes in response to a change in the temperature of the tire component that forms part of the tire. In the present embodiment, the rigidity of the bead filler4bis higher than the rigidity of the side rubber portion60A. The temperature dependence of the bead filler4bis therefore greater than the temperature dependence of the side rubber portion60A. In other words, as illustrated inFIG.12, the change in rigidity (U1) of the bead filler4bdue to a change in temperature is greater than the change in rigidity (U2) of side rubber portion60A due to a change in temperature.

Turbulence-generating projections70(F) extending along the tire radial direction RD are provided in at least a portion of this tire side portion1d.

As illustrated inFIGS.10and11, the turbulence-generating projection70projects from the surface of the tire side portion1d.The cross-sectional shape of the turbulence-generating projection70orthogonal to the extending direction thereof is rectangular.

The turbulence-generating projections70are provided only in the low-rigidity portion61, i.e., only in the side rubber portion60A. Specifically, the turbulence-generating projections70are provided only in the region from the ground edge51to the tire radial outer end4buof the bead filler4b.In other words, the turbulence-generating projections70are provided at a position not in overlap with the bead filler4bin the tire width direction.

The cross-sectional shape of the turbulence-generating projection70does not necessarily have to be rectangular and may be any of various shapes, such as a trapezoid or semi-circular arc. It suffices for the turbulence-generating projection70to be provided within the region from the ground edge51to the tire radial outer end4buof the bead filler4b,and a plurality thereof may be provided separately.

For example, if turbulence-generating projections are provided on the entire surface of the tire side portion, the entire surface of the tire side portion is cooled by the turbulence-generating projections. However, if the temperature of the entire tire side portion decreases, then the rigidity difference (d2) between the rigidity of the bead filler (for example, T1) and the rigidity of the side rubber portion (for example, T2′) is large, as illustrated inFIG.12. Therefore, the less the bead filler flexes (deforms), the more the tire side portion flexes. As a result, distortion tends to be concentrated at a tire widthwise end6eof the belt6(hereinafter the belt end6e), which may cause separation at the belt end6e.

Therefore, in the fourth embodiment, the turbulence-generating projections70are provided only in the low-rigidity portion61(side rubber portion60A). In other words, the turbulence-generating projections70do not overlap in the tire width direction with the high-rigidity portion62(bead filler4b), which has higher rigidity than the side rubber portion60A. Therefore, the turbulence caused by the turbulence-generating projections70as the tire1rotates will cool only the side rubber portion60A.

Since the side rubber portion60A is cooled by turbulence, its temperature does not rise easily, resulting in less rigidity loss. On the other hand, the bead filler4b,which has greater temperature dependence than the side rubber portion60A, is not cooled by turbulence, and thus its temperature rises, causing a gradual decrease in rigidity. Therefore, as illustrated inFIG.12, the rigidity difference between the rigidity of the side rubber portion60A and the rigidity of the bead filler4bbecomes smaller as the rigidity of the bead filler4bgradually decreases in a predetermined temperature range R.

Accordingly, in a temperature range of the tire when the vehicle is traveling at very high speed (a predetermined temperature range R), for example, the rigidity difference (d1) between the rigidity of the side rubber portion60A (for example, T1) and the rigidity of the bead filler4b(for example, T2) can be reduced, as illustrated inFIG.12, making it easier for the bead filler4bto flex together with the side rubber portion60A.

This can prevent the concentration of distortion (deformation) at the belt end6edue to the rigidity difference between the rigidity of the side rubber portion60A and the rigidity of the bead filler4bin the temperature range of the tire when the vehicle is traveling at very high speed, for example. As a result, separation at the belt end6ecan be reliably suppressed.

Since the turbulence-generating projections70do not overlap in the tire width direction with the high-rigidity portion62(bead filler4b), which has a higher rigidity than the side rubber portion60A, the thickness of the side rubber portion60A does not increase at the tire widthwise outer side of the bead filler4bdue turbulence-generating projections projecting from the surface of the tire side portion. Therefore, even when the vehicle travels at very high speed, the side rubber portion60A and the bead filler4breliably flex together, and the concentration of strain on the belt end6ecan be reliably suppressed.

The tire1according to the fifth embodiment of the present disclosure is described below with reference toFIGS.13to15.

In the tire1of the fifth embodiment, the projection width, defined as the length of the turbulence-generating projection F in the tire circumferential direction, varies in the tire radial direction and widens toward a projection outer end located on the tire radial outer side, and the height of the turbulence-generating projection F relative to the tire outer surface1dsof the tire side portion1dvaries in the tire radial direction and is formed to decrease gradually toward the projection outer end.

A plurality of turbulence-generating projections110(F) project from the tire outer surface1dsof the tire side portion1d,extend along the tire radial direction, and are arranged at intervals in the tire circumferential direction. The turbulence-generating projections110are arranged radially, centering on the tire rotation axis, on the tire outer surface1dsof the tire side portion1d, as illustrated inFIG.13.

The turbulence-generating projection110is an elongated projection for generating or promoting turbulence on the tire outer surface of the tire side portion1dduring rotation of the tire1. As illustrated inFIG.15, the projection outer end111, which is the outer end of the turbulence-generating projection110in the tire radial direction, is formed with a slope so that the height110H gradually becomes lower toward the edge. The tire widthwise outer surface of the turbulence-generating projection110at the projection outer end111(the surface visible from the tire side) is continuous with the tire outer surface1dsof the tire side portion1dso as to be flush with the tire outer surface1ds. As illustrated inFIG.15, the maximum angle1θ1between the tire widthwise outer surface of the turbulence-generating projection110at the projection outer end111and the tire outer surface1dsof the tire side portion is set to be 25° or less. Specifically, the maximum angle1θ1is approximately 22° in the present embodiment.

The projection inner end112, which is the inner end of the turbulence-generating projection110in the tire radial direction, is formed to be smoothly continuous with the tire outer surface1ds, which rises up from the bead portion1cand extends from the rim guard in the tire radial direction, so as to be flush with the tire outer surface1ds.

On the tire radial outer side of the turbulence-generating projection110, characters and symbols for conveying information are provided. These characters and symbols are protrusions130that project from the tire side portion1d.These protrusions130also generate turbulence in the fluid passing along the tire side portion1dand thus have a cooling effect on the tire side portion1d.

The radial length110L (FIG.14), which is the length of the turbulence-generating projection110in the tire radial direction, is 12 mm, for example. The maximum height110H (FIG.15) of the turbulence-generating projection110relative to the tire outer surface1dsof the tire side portion1dis, for example, 0.7 mm. The length130L of the protrusion130in the tire radial direction is, for example, 10 mm.

In the present embodiment, as illustrated inFIG.14, turbulence-generating projections110adjacent to each other are set at predetermined intervals. The projection width of the turbulence-generating projection110varies so as to widen towards the tire radial outer side (the tread portion1aside). The interval1P (FIG.14) between the turbulence-generating projections110is, for example, 11 mm.

For example, the projection width111W (FIG.14) of the projection outer end111of the turbulence-generating projection110is 4.665 mm to 7.141 mm, and the projection width112W (FIG.14) of the projection inner end112is 1.202 mm to 1.454 mm. The projection width111W of the projection outer end111and the projection width112W of the projection inner end112can be adjusted as needed for each tire size.

Specifically, for example, the projection width111W of the projection outer end111of a 225/50F17 tire is 7.141 mm, the projection width112W of the projection inner end112is 1.202 mm, and the ratio of the projection width111W of the projection outer end111to the projection width112W of the projection inner end112is 5.941. The projection width111W of the projection outer end111of a 225/45F17 tire is 5.378 mm, the projection width112W of the projection inner end112is 1.454 mm, and the ratio of the projection width111W of the projection outer end111to the projection width112W of the projection inner end112is 3.699. The projection width111W of the projection outer end111of a 245/40F18 tire is 4.665 mm, the projection width112W of the projection inner end112is 1.346 mm, and the ratio of the projection width111W of the projection outer end111to the projection width112W of the projection inner end112is 3.466. The projection width111W of the projection outer end111of a 225/50F16 tire is 6.844 mm, the projection width112W of the projection inner end112is 1.392 mm, and the ratio of the projection width111W of the projection outer end111to the projection width112W of the projection inner end112is 4.917.

The projection width111W is configured to have a length of 25% or more of the interval1P of the turbulence-generating projections110. Specifically, the projection width111W of the projection outer end111is 50% or more of the interval1P between adjacent turbulence-generating projections110. In addition, the adjacent turbulence-generating projections110are configured not to be connected. The aforementioned interval1P between the turbulence-generating projections110is the distance between points bisecting the width of the turbulence-generating projections110in the tire circumferential direction.

The shapes of the two sides of the turbulence-generating projection in the longitudinal direction differ from each other. The shape of one side is substantially parallel to the longitudinal direction and is substantially straight. The shape of the other side has a gently sloping portion113, which is substantially parallel to the one side, and a steeply sloping portion114, which is more inclined relative to the longitudinal direction than the gently sloping portion113. The area near the projection outer end111is the steeply sloping portion114. Therefore, the turbulence-generating projection110has an increasingly larger projection width toward the projection outer end111.

Of the width ends111A and111B, which are the ends in the tire circumferential direction of the projection outer end111of the turbulence-generating projection110, one width end111A is formed so that the angle1θ3between a circumferential side1E1extending in the tire circumferential direction and a radial side1E2extending in the tire radial direction is 90° or less. According to such a configuration, at least one end of the projection outer end in the tire circumferential direction is 90° or less, i.e., an acute angle, which facilitates extraction of the tire from the mold during manufacturing and also facilitates the release of air to the tire surface during vulcanization, effectively suppressing the occurrence of bare portions during manufacturing and reducing the probability of a defective shape or defective appearance.

According to the tire1of the fifth embodiment, the temperature of the tire side portion1dcan be reduced by the turbulence-generating projections110, since the turbulence-generating projections110are provided on the tire side portion1d.In addition, since the height of the projection outer end111of the turbulence-generating projection110gradually decreases toward the surface of the tire side portion, the occurrence of chips and broken-off portions of the turbulence-generating projections110is reduced and bare portions are less likely to occur when the raw tire is vulcanized in the mold for forming a tire.

Furthermore, the projection width111W at the projection outer end111of the turbulence-generating projection110is 2.0 times or more the projection width112W at the projection inner end112of the turbulence-generating projection110. A sufficient temperature reduction effect can thereby be obtained while avoiding the problem of heat storage.

The maximum angle1θ1between the tire widthwise outer surface of the turbulence-generating projection110and the tire outer surface1dsof the tire side portion is set to be 25° or less (for example, approximately 22°). Therefore, the occurrence of chips and broken-off portions of the projection outer end111of the turbulence-generating projection110is reduced and bare portions are less likely to occur when the raw tire is vulcanized in the mold for forming a tire during manufacturing.

Furthermore, since the projection width111W is 25% or more of the interval1P between turbulence-generating projections110, and adjacent turbulence-generating projections110are not connected to each other, a temperature rise due to heat storage caused by an excessively large projection width and a decrease in rigidity due to an excessively narrow projection width can be avoided while effectively achieving the diffusion of turbulence. A heat storage suppression function and a turbulence promotion function (cooling function) can thus both be achieved.

The width end111A of the projection outer end111of the turbulence-generating projection110is formed so that the angle1θ3between the circumferential side1E1extending in the tire circumferential direction and the radial side1E2extending in the tire radial direction is 90° or less, which facilitates extraction from the mold during manufacturing and also facilitates the release of air to the tire surface during vulcanization. This effectively suppresses the occurrence of bare portions during manufacturing and reduces the probability of a defective shape or defective appearance.

Since the projection inner end112of the turbulence-generating projection110is continuous so as to be flush with the tire outer surface1ds, the rigidity of the projection inner end112can be enhanced to suppress damage, such as chips and broken-off portions. This also suppresses the occurrence of bare portions during manufacturing and reduces the probability of a defective shape or defective appearance.

The tire1according to the sixth embodiment of the present disclosure is described below with reference toFIGS.16and17.

In the tire1of the sixth embodiment, the tire side portion1dhas provided thereon a first region in which a plurality of the turbulence-generating projections F are arranged adjacent to each other, and a second region at least partially overlapping the first region in the tire circumferential direction and not having any turbulence-generating projections F arranged therein. A protrusion projecting from the tire outer surface1dsof the tire side portion1dis formed in the second region. The protrusion has the shape of characters and symbols displaying information or the shape of figures and patterns displaying a design. The protrusion has a height from the tire outer surface1dsof the tire side portion1dthat is from 50% to 100% of the height of the turbulence-generating projection F from the tire outer surface1dsof the tire side portion1d.

As illustrated inFIG.16, the tire outer surface1dsof the tire side portion1dhas provided thereon a first region2R1in which a plurality of turbulence-generating projections210(F) are arranged adjacent to each other and a second region2R2in which no turbulence-generating projections210(F) are arranged adjacent to each other. In the second region2R2, a plurality of protrusions220are arranged adjacent to each other. The first region2R1and the second region2R2are arranged to partially overlap in the tire circumferential direction.

The plurality of turbulence-generating projections210(F) project from the tire outer surface1dsof the tire side portion1d,extend along the tire radial direction, and are arranged at intervals in the tire circumferential direction. The turbulence-generating projections210are arranged radially, centering on the tire rotation axis, on the tire outer surface1dsof the tire side portion1d, as illustrated inFIG.16. Each turbulence-generating projection210extends so that the longitudinal direction is along the tire radial direction. A cross-section of the turbulence-generating projection210in the tire circumferential direction is formed to have a rectangular shape. The turbulence-generating projection210is an elongated projection for generating or promoting turbulence on the tire outer surface1dsof the tire side portion1dduring rotation of the tire1.

The plurality of protrusions220project from the tire outer surface1dsof the tire side portion1dand are arranged at intervals in the tire circumferential direction. As illustrated inFIG.16, the protrusions220are in the shape of characters, recognizable when viewed from the outside of the tire side portion1d,and display predetermined information. A cross-section of the protrusions220in the tire circumferential direction is formed to have a rectangular shape. The protrusions220generate or promote turbulence on the outer circumferential surface of the tire side portion1dduring rotation of the tire1.

Projections230project from the tire outer surface1dsof the tire side portion1d.The projections230are arranged at intervals along the tire circumferential direction on the tire radial inner side of the protrusions220. The projections230generate or promote turbulence on the outer circumferential surface of the tire side portion1dduring rotation of the tire1. The projections230are arranged radially, centering on the tire rotation axis, on the tire outer surface1dsof the tire side portion1d,as illustrated inFIG.16.

Each projection230extends so that the longitudinal direction is along the tire radial direction. A cross-section of the projections230in the tire circumferential direction is substantially rectangular. The pitch of the projections230in the tire circumferential direction is the same length as the pitch2P of the turbulence-generating projections210in the tire circumferential direction.

By the turbulence-generating projections210(F) thus being arranged in the first region2R1and the projections230and protrusions220being arranged in the second region2R2, turbulence can be generated or promoted over the entire circumference of the tire outer surface1dsof the tire side portion1dto effectively reduce the tire temperature.

The mechanism of turbulence generation is now explained. As the tire1rotates, the air flow S1in contact with the tire outer surface1dsof the tire side portion1dwhere the turbulence-generating projection210or protrusion220is not formed is detached from the tire outer surface1dsby the turbulence-generating projection210or protrusion220and overcomes the turbulence-generating projection210or protrusion220. On the back side of the turbulence-generating projection210or the protrusion220, a portion (region) S2is created in which the air flow is stagnant.

The air flow S1then reattaches to the bottom between the back side and the next turbulence-generating projection210or protrusion220and is detached again at the next turbulence-generating projection210or protrusion220. At this time, a portion (region) S3is created in which the air flow is stagnant between the air flow S1and the next turbulence-generating projection210and the like. Here, increasing the velocity gradient (speed) over the region in contact with the turbulence S1is considered advantageous for increasing the cooling effect. In other words, provision of the turbulence-generating projections210and protrusions220on the tire outer surface1dsof the tire side portion1dgenerates the air flow S1with a high flow rate and the stagnant portions S2, S3and promotes the generation of turbulence on the tire outer surface1dsof the tire side portion1d,thereby enhancing the cooling effect of the tire side portion1d.

The projections230on the tire radial inner side in the tire side portion1dalso contribute to heat dissipation on the tire radial outer side. Specifically, a centrifugal force during rotation of the tire1causes air to flow from the inside to the outside in the tire radial direction. The projections230provided on the tire radial inner side thereby also contribute to heat dissipation on the tire radial outer side. By the turbulence-generating projections210and the projections230being provided at least in a portion on the tire radial inner side of the tire side portion1d,heat dissipation can be promoted not only in the portion on the tire radial inner side but also the portion on the tire radial outer side, thereby efficiently enhancing the cooling effect on the entire tire outer surface1dsof the tire side portion1d.

In the tire1of the present embodiment, the height210H of the turbulence-generating projection210from the tire outer surface1dsis, for example, 0.7 mm. The height220H of the protrusion220from the tire outer surface1dsis, for example, 0.6 mm. The height220H of the protrusion220is preferably in a range of 50% to 100% of the height210H of the turbulence-generating projection210, for example 86%. If the height220H of the protrusion220, the height210H of the turbulence-generating projection210, and the height230H of the projection230are too large, the deformation of the tire side portion during rolling becomes difficult to follow, and subjection to repeated deformation may concentrate strain especially at the base of the turbulence-generating projection, causing cracks to occur.

On the other hand, if the height220H of the protrusion220is too small relative to the height210H of the turbulence-generating projection210, i.e., less than 50% of the height210H of the turbulence-generating projection210, then the visibility of the characters may be reduced, or the turbulence generation effect may not be sufficiently obtained. Therefore, the height220H of the protrusion220is preferably within a range of 50% to 100% of the height210H of the turbulence-generating projection210.

The protrusion220is arranged so as to overlap, in the tire circumferential direction, a tire radial outer end210X of the turbulence-generating projection210. In other words, the protrusion220is arranged on a virtual line2C1extending in the tire circumferential direction through the outer end210X of the turbulence-generating projection210. An outer end220X of the protrusion220is disposed farther outward in the tire radial direction than the outer end210X of the turbulence-generating projection210, and the length221L (FIG.16) in the tire radial direction from the outer end220X of the protrusion220to the outer end210X of the turbulence-generating projection210is, for example, 6.4 mm.

The length221L (FIG.16) in the tire radial direction from the outer end220X of the protrusion220to the outer end210X of the turbulence-generating projection210is preferably 2 mm to 8 mm. The distance in the tire radial direction between the projection230and the protrusion220is preferably set from approximately 1.5 mm to 3 mm, more preferably 2 mm. The distance between the turbulence-generating projection210and the protrusion220is preferably set from approximately 6 mm to 12 mm in the circumferential direction.

A tire radial inner end230Y of the projection230is arranged so as to overlap, in the tire circumferential direction, a tire radial inner end210Y of the turbulence-generating projection210. In other words, the projection230is arranged on a virtual line2C2extending in the tire circumferential direction through the inner end210Y of the turbulence-generating projection210. By the protrusions220and the projections230being arranged in this manner, air moving along the tire circumferential direction can continuously contact the turbulence-generating projections210and the protrusions220.

The length220L of the protrusion220in the tire radial direction is from 30% to 80% of the length220L of the turbulence-generating projection210in the tire radial direction. If the length220L of the protrusion220is too small relative to the length210L of the turbulence-generating projection210, i.e., less than 30%, then the visibility of the characters may be reduced, or the turbulence generation effect may not be sufficiently obtained. Therefore, the length220L of the protrusion220is preferably within a range of 30% to 80% of the length210L of the turbulence-generating projection210.

According to the tire1configured as described above, the turbulence-generating projections210are provided in the first region2R1, and the protrusions220and projections230are provided in the second region2R2. This enables a reduction in the temperature of the second region2R2through the protrusions220and the projections230while maintaining the effect of reducing the temperature in the first region2R1through the turbulence-generating projections. In addition, since characters can be displayed by the protrusions220, the effect of reducing the temperature through air turbulence and the effect of conveying information can both be achieved.

The tire1according to the seventh embodiment of the present disclosure is described below with reference toFIGS.18to21.

The tire1of the seventh embodiment further includes a circumferential projection projecting from the tire outer surface1dsof the tire side portion1dand extending in the tire circumferential direction. An end of the turbulence-generating projection F in the tire radial direction is connected to the circumferential projection, and the height of the end of the turbulence-generating projection F relative to the tire outer surface1dsof the tire side portion1dis lower than the height of the circumferential projection relative to the tire outer surface1dsof the tire side portion1dat a portion at which the end of the turbulence-generating projection F and the circumferential projection are connected in the tire radial direction.

Also, in the tire1of the seventh embodiment, in the tire side portion1d,the tire1has a tire maximum width region TR that includes a position at which a length of the tire in the tire width direction is maximized, an end of the turbulence-generating projection F in the tire radial direction is located in the tire maximum width region TR, the tire1includes a circumferential projection projecting from the tire outer surface1dsof the tire side portion1dand extending in the tire circumferential direction, the end of the turbulence-generating projection F is connected to the circumferential projection, and the width of the circumferential projection in the tire radial direction is narrower than the maximum width of the turbulence-generating projection F in the tire circumferential direction.

As illustrated inFIG.18, a plurality of turbulence-generating projections310(F) are arranged on the tire outer surface1dsof the tire side portion1d.In addition, a circumferential projection315extending in the tire circumferential direction is arranged on the tire outer surface1dsof the tire side portion1d.Therefore, the tire1includes the turbulence-generating projections310and the circumferential projection315. The tire outer surface1dsof the tire side portion1dis configured by a tire outer surface3A, a tire outer surface3B, and a tire outer surface3C. The tire outer surface3A of the tire side portion1dis the surface between the tire outer surface3B and the tire outer surface3C in the tire radial direction. The tire outer surface3B of the tire side portion1dis the surface located on the tire radial inner side of the turbulence-generating projections310. The tire outer surface3C of the tire side portion1dis the surface located on the tire radial outer side of the circumferential projection315.

The tire1has a maximum tire width that is the maximum length of tire1in the tire width direction. The maximum tire width referred to here does not, for example, include the maximum width between rim guards in the tire width direction in a tire that is provided with rim guards. In other words, the maximum tire width does not include the rim guards. The height of the tire maximum width position (maximum width height SWH) with respect to the height of the inner end of the bead portion1cin the radial direction is located at 48% or more of the height of the tread surface (tread surface height TH) on the tire equatorial plane CL with respect to the height of the inner end of the bead portion1cin the radial direction when the tire is not inflated.

In the tire side portion1d,the tire1has a tire maximum width region TR (FIG.21) that includes the tire maximum width position at which the length of the tire1in the tire width direction is maximized. In other words, the maximum width region TR is the surface of the tire side portion1d,in the tire radial direction, located at a height including the maximum width height SWH (FIG.21). The range of the tire maximum width region TR in the tire radial direction is a region within 25% of the tread surface height TH. The tire maximum width position (indicated by a dashed dotted line inFIG.21) is located at the tire radial center of the tire maximum width region TR.

For example, the maximum width region TR in the tire radial direction is a range of 60 mm. In this case, the range of the tire maximum width region TR in the tire radial direction is centered on the tire maximum width position and extends 30 mm outward in the tire radial direction and 30 mm inward in the tire radial direction.

FIG.19is a partially enlarged view of the turbulence-generating projection310illustrated inFIG.18.FIG.20Ais a partially enlarged view of the turbulence-generating projection310illustrated inFIG.18.FIG.20Bis a cross-sectional view orthogonal to the extending direction of the turbulence-generating projection310illustrated inFIG.20A. Specifically,FIG.20Bis an E-E cross-sectional view ofFIG.20A.FIG.21Ais a partial cross-sectional view of the tire1along the tire width direction and the tire radial direction.FIG.21Bis a partial cross-sectional view of the tire1along the tire width direction and the tire radial direction. Specifically,FIGS.21A and21Bare D-D cross-sectional views ofFIG.19.

In the tire1of the present embodiment, a plurality of turbulence-generating projections310are provided on the tire outer surface3A of the tire side portion1dto generate or promote turbulence, thereby enhancing the cooling effect at the tire side portion1d.

The plurality of turbulence-generating projections310project from the tire outer surface3A of the tire side portion1d,extend along the tire radial direction, and are arranged at intervals in the tire circumferential direction. The turbulence-generating projections310are arranged radially, centering on the tire rotation axis, on the tire outer surface3A of the tire side portion1d,as illustrated inFIG.18. The turbulence-generating projection310extends at an inclination relative to the tire radial direction. Therefore, the length of the turbulence-generating projection310in the extending direction is longer than the length of the turbulence-generating projection310along the tire radial direction. The ends of the turbulence-generating projection310in the tire radial direction have a projection outer end311located on the outer side of the turbulence-generating projection310in the tire radial direction and a projection inner end312located on the inner side of the turbulence-generating projection310in the tire radial direction. The circumferential projection315projects from the tire outer surface3A of the tire side portion1dand extends along the tire circumferential direction. The circumferential projection315is annular as viewed from the tire radial direction.

The turbulence-generating projection310is an elongated projection for generating or promoting turbulence on the tire outer surface1dsof the tire side portion1dduring rotation of the tire1. As illustrated inFIG.21, the projection outer end311, which is the outer end of the turbulence-generating projection310in the tire radial direction, is located in the tire maximum width region TR. The projection outer end311is connected to the circumferential projection315. Specifically, the projection outer end311is connected to the surface on the inner side of the circumferential projection315in the tire radial direction. The projection outer end311is in contact with the surface on the inner side of the circumferential projection315in the tire radial direction.

At the portion where the projection outer end311and the circumferential projection315are connected, a height311H of the projection outer end311relative to the tire outer surface3A of the tire side portion1d(FIG.21B) is lower than a height315H of the circumferential projection315relative to the tire outer surface3A of the tire side portion1d(FIG.21B). In other words, the height315H of the circumferential projection315relative to the tire outer surface3A of the tire side portion1dis higher than the height311H of the projection outer end311relative to the tire outer surface3A of the tire side portion1d.Therefore, a step with different heights along the tire width direction is formed at the portion where the projection outer end311and the circumferential projection315are connected.

The projection inner end312of the turbulence-generating projection310is smoothly connected to the tire outer surface3B of the tire side portion1d,which is on the tire radial inner side of the turbulence-generating projection310. In other words, no step with different heights along the tire width direction is formed at the portion where the projection inner end312and the tire outer surface3B are connected. In the portion where the projection inner end312and the tire outer surface3B are connected, the height of the projection inner end312relative to the tire outer surface3A of the tire side portion1dis the same as the height of the tire outer surface3B relative to the tire outer surface3A of the tire side portion1d.In other words, the projection inner end312of the turbulence-generating projection310is continuous so as to be flush with the tire outer surface3B. Therefore, the rigidity of the projection inner end312can be enhanced to suppress damage, such as chips and broken-off portions. This also suppresses the occurrence of bare portions during manufacturing and reduces the probability of a defective shape or defective appearance.

On the tire outer surface3C of the tire side portion1d,which is on the tire radial outer side of the circumferential projection315, characters and symbols for conveying information are provided.

In the present embodiment, as illustrated inFIG.19, turbulence-generating projections310adjacent to each other are set at predetermined intervals. The projection width, which is the width of the turbulence-generating projection310in the tire circumferential direction, varies so as to widen towards the tire radial outer side (the tread portion la side). Therefore, the centrifugal force generated by tire rotation and vehicle travel causes the fluid moving from the inside to the outside in the tire radial direction to contact the turbulence-generating projection310, thereby enhancing the effect of cooling the temperature of the tire side portion1d.In addition, the fluid moving outward in the tire radial direction can be easily guided to the turbulence-generating projection310adjacent in the tire circumferential direction, thereby enhancing the cooling effect over the entire tire side portion1d.

The shapes of the two sides of the turbulence-generating projection310in the longitudinal direction (i.e., the extending direction of the turbulence-generating projection310) differ from each other. The shape of one side is substantially parallel to the longitudinal direction and is substantially straight. The shape of the other side has a gently sloping portion313, which is substantially parallel to the one side, and a steeply sloping portion314, which is more inclined relative to the longitudinal direction than the gently sloping portion313. The area near the projection outer end311is the steeply sloping portion314. Therefore, the turbulence-generating projection310has an increasingly larger projection width toward the projection outer end311.

Of the width ends311A and311B, which are the ends in the tire circumferential direction of the projection outer end311of the turbulence-generating projection310, one width end311A is formed so that the angle3θe (FIG.19) between a circumferential side3E1extending in the tire circumferential direction and a radial side3E2extending in the tire radial direction is 90° or less.

The projection inner end312of the turbulence-generating projection310includes width ends312A and312B, which are ends in the tire circumferential direction. A line that, when viewed from the tire width direction, passes through the approximate tire circumferential center of the width ends312A and312B and is substantially parallel to the surface on the width end312B side in the tire circumferential direction is designated as a line m (FIG.20A). A line that passes through the boundary between the gently sloping portion313and the steeply sloping portion314and is parallel to the line m is designated as a line n (FIG.20A). The distance311Wa between the line m and the line n is, for example, 1.4 mm in the present embodiment. The distance311Wb between the width end311B and the line m is, for example, 1.2 mm. The projection width311W of the projection outer end311of the turbulence-generating projection310is, for example, 4.7 mm to 7.1 mm.

The distance312Wa between the line m and one width end312A of the width ends312A and312B, which are the ends in the tire circumferential direction of the projection inner end312of the turbulence-generating projection310, is 0.7 mm, for example, in the present embodiment. The distance312Wb between the line m and the other width end312B is, for example, 0.8 mm in the present embodiment. The projection width312W of the projection inner end312is, for example, 1.2 mm to 1.5 mm. The projection width311W of the projection outer end311and the projection width312W of the projection inner end312can be adjusted as needed for each tire size.

The length310L (FIG.20A) in the tire radial direction from the projection outer end311to the projection inner end312of the turbulence-generating projection310is preferably in a range of 8 mm to 30 mm.

In the present embodiment, one side of the turbulence-generating projection310as viewed from the tire width direction is arc-shaped. The radius of curvature Ra of the one side of the turbulence-generating projection310is, for example, constant at 180 mm. As viewed from the tire width direction, the gently sloping portion313has an arc-shaped side surface. The radius of curvature Rb of the side surface of the gently sloping portion313is, for example, constant at 180 mm. As viewed from the tire width direction, the steeply sloping portion314has an arc-shaped side surface. The radius of curvature Rc of the side surface of the steeply sloping portion314is, for example, 0.8 times the length310L. The radius of curvature Rc is preferably in a range of 12 mm to 20 mm. The end of the tire outer surface3B of the tire side portion1din the tire radial direction extends along the tire circumferential direction.

The end of the tire outer surface3B in the outer tire radial direction is arc-shaped when viewed from the tire width direction. The number and pitch angle3θp of the turbulence-generating projections310may be determined by the radius of curvature Rd of the end of the tire outer surface3B on the tire radial outer side. For example, in a case in which the radius of curvature Rd is 147.2 mm to 165.4 mm, the number of turbulence-generating projections310is 90, and the pitch angle3θp is 4 degrees. In a case in which the radius of curvature Rd is 165.5 mm to 176.5 mm, the number of turbulence-generating projections310is 96, and the pitch angle3θp is 3.8 degrees. In a case in which the radius of curvature Rd is 176.6 mm to 183.8 mm, the number of turbulence-generating projections310is 100, and the pitch angle3θp is 3.6 degrees. In a case in which the radius of curvature Rd is 183.9 mm to 220.6 mm, the number of turbulence-generating projections310is 120, and the pitch angle3θp is 3 degrees. In a case in which the radius of curvature Rd is 220.7 mm to 229.8 mm, the number of turbulence-generating projections310is 125, and the pitch angle3θp is 2.9 degrees. In a case in which the radius of curvature Rd is 229.9 mm to 264.7 mm, the number of turbulence-generating projections310is 144, and the pitch angle3θp is 2.5 degrees. In a case in which the radius of curvature Rd is 264.8 mm to 275.7 mm, the number of turbulence-generating projections310is 150, and the pitch angle3θp is 2.4 degrees. In a case in which the radius of curvature Rd is 275.8 mm to 294.1 mm, the number of turbulence-generating projections310is 160, and the pitch angle3θp is 2.3 degrees. In a case in which the radius of curvature Rd is 294.2 mm to 330.9 mm, the number of turbulence-generating projections310is 180, and the pitch angle3θp is 2 degrees. In a case in which the radius of curvature Rd is 331.0 mm to 352.9 mm, the number of turbulence-generating projections310is 192, and the pitch angle3θp is 1.9 degrees. In a case in which the radius of curvature Rd is 353.0 mm to 367.6 mm, the number of turbulence-generating projections310is 200, and the pitch angle3θp is 1.8 degrees.

The pitch angle3θp is the angle between one turbulence-generating projection310and another turbulence-generating projection310adjacent to the one turbulence-generating projection310, with the rotation axis of the tire as the center. Specifically, the pitch angle3θp is the angle formed between lines extending from the rotation axis of the tire through points bisecting the length310L on the lines m of adjacent turbulence-generating projections310.

The angle3θa between a line parallel to the tire radial direction and the line m is preferably in a range of 10° to 45°. In the present embodiment, the angle3θa between the line parallel to the tire radial direction and the line m is, for example, 27°.

As illustrated inFIG.20B, in a cross-section orthogonal to the extending direction of the turbulence-generating projection310, the turbulence-generating projection310and the tire outer surface3A of the tire side portion1dare preferably connected in the shape of an arc. In the present embodiment, the radius of curvature Re of the arc is, for example, 0.4 mm. The angle3θb between the side surface of the turbulence-generating projection310facing the tire circumferential direction and a line parallel to the tire width direction is preferably in a range of 3° to 15°. In the present embodiment, the angle3θb is 10°.

As illustrated inFIG.21B, the height310H of the tire side portion1dfrom the tire outer surface3A is preferably in a range of 0.5 mm to 1.5 mm.

The cooling effect is enhanced by the height310H being 0.5 mm or more. By the height310H being 1.5 mm or less, the depth to the bottom of the recess in the tire mold for forming the turbulence-generating projections310is not deep. Rubber material can thereby easily enter to the bottom of the recess in the tire mold for forming the turbulence-generating projections310. Therefore, the occurrence of bare portions in the turbulence-generating projections310can be suppressed. In the present embodiment, the height310H is, for example, constant at 0.7 mm.

The height315H of the circumferential projection315from the tire outer surface3A is preferably in a range of 0.5 mm to 1.5 mm. By the height315H being 0.5 mm or more, air accumulated in the recess in the tire mold for forming the circumferential projection315is less likely to move into the recess in the tire mold for forming the projection outer end311. Therefore, the occurrence of bare portions in the turbulence-generating projections310can be suppressed. By the height315H being 1.5 mm or less, the length to the bottom of the recess in the tire mold for forming the circumferential projection315is shortened. Rubber material can thereby easily enter to the bottom of the recess in the tire mold for forming the projection outer end311. Therefore, the occurrence of bare portions in the circumferential projection315can be suppressed. In the present embodiment, the height315H is, for example, 0.9 mm. As described above, the height315H is higher than the height310H in the present embodiment.

In the present embodiment, the width of the circumferential projection315in the tire radial direction varies along the tire width direction. Specifically, the width of the circumferential projection315becomes narrower farther outward in the tire width direction. Accordingly, the width315La, in the tire radial direction, of the upper surface315a(the surface facing the tire radial direction) of the circumferential projection315is narrower than the width315Lb, in the tire radial direction, of the circumferential projection315on the tire outer surface1dsof the tire side portion1d.In other words, the shape of the circumferential projection315is trapezoidal in a cross-section along the tire radial direction and the tire width direction. The width315La and the width315Lb preferably satisfy the expressions 0.2 mm≤width315La≤3 mm, and 1.5 mm≤width315Lb≤5.0 mm. By the width315La being 0.2 mm or more and the width315Lb being 1.5 mm or more, the rubber material configuring the circumferential projection315can easily enter the recess in the tire mold for forming the circumferential projection315. Consequently, the occurrence of bare portions in the circumferential projection315can be suppressed. Setting the width315La to 3 mm or less and the width315Lb to 5.0 mm or less enables a reduction in the amount of rubber material used and a reduction in weight of the tire side portion1d.

The width of the circumferential projection315in the tire radial direction is narrower than the maximum width of the turbulence-generating projection310in the tire circumferential direction. In the present embodiment, the maximum width of the turbulence-generating projection310in the tire circumferential direction is the width of the projection outer end311in the tire circumferential direction. In other words, this is the projection width311W of the projection outer end311of the turbulence-generating projection310. Specifically, the maximum width of the turbulence-generating projection310in the tire circumferential direction is the length, in the tire circumferential direction, from one width end311A to the other width end311B. In the present embodiment, the width315La of the circumferential projection315is narrower than the width of the projection outer end311in the tire circumferential direction. Specifically, the width of the projection outer end311in the tire circumferential direction is, for example, 5 mm. The width315La of the circumferential projection315is, for example, 3.0 mm. The width315Lb of the circumferential projection315is narrower than the width of the projection outer end311in the tire circumferential direction.

According to the tire1of the seventh embodiment, the projection outer end311is connected to the circumferential projection315. In other words, in the tire radial direction, the circumferential projection315is located on the outer side of the projection outer end311. Furthermore, the height311H of the projection outer end311relative to the tire outer surface3A of the tire side portion1dis lower than the height315H of the circumferential projection315relative to the tire outer surface3A of the tire side portion1dat a portion at which the projection outer end311of the turbulence-generating projection310and the circumferential projection315are connected in the tire radial direction.

When a raw tire is vulcanized in a tire mold, air that tends to accumulate in the corners of the recess in the tire mold for forming the projection outer end311moves to the recess in the tire mold for forming the circumferential projection315. Therefore, rubber material can reach the bottom of the recess of the tire mold for forming the projection outer end311of the turbulence-generating projection310without being obstructed by air, thereby suppressing the formation of a bare portion at the projection outer end311.

Since the height311H of the projection outer end311relative to the tire outer surface3A of the tire side portion1dis lower than the height315H of the circumferential projection315relative to the tire outer surface3A of the tire side portion1dat a portion at which the projection outer end311and the circumferential projection315are connected, a step with a different heights along the tire width direction is formed between the bottom of the recess for forming the circumferential projection315and the bottom of the recess for forming the projection outer end311. Accordingly, when a raw tire is vulcanized in a mold for forming a tire, air accumulated in the recess for forming the circumferential projection315must cross the step in order to move to the recess for forming the projection outer end311. The air accumulated in the recess for forming the circumferential projection315is pushed to the bottom of the recess for forming the circumferential projection315by the rubber material that enters the recess. Therefore, air accumulated in the recess for forming the circumferential projection315is less likely to cross the step and move into the recess forming the turbulence-generating projection310.

Furthermore, since the height311H of the projection outer end311is lower than the height315H of the circumferential projection315, the rubber material can easily reach the bottom of the recess for forming the projection outer end311.

As a result of these effects, air is less likely to accumulate in the corners of the recesses of the tire mold for forming the projection outer end311, and rubber material can more easily move to enter the recesses of the tire mold for forming the projection outer end311. Therefore, the occurrence of bare portions in the projection outer end311can be suppressed.

The temperature of the tire side portion1dcan be reduced by the turbulence-generating projections310, since the turbulence-generating projections310are provided on the tire side portion1d.Furthermore, the circumferential projection315is provided on the tire side portion1d. Therefore, air having a radial component in the tire radial direction overcomes the circumferential projection315. The air that comes over then flows in a direction substantially perpendicular to the tire outer surface3C on the back side of the circumferential projection315and strikes the tire outer surface3C located on the tire radial outer side of the circumferential projection315. Therefore, the air flow striking the tire outer surface3C exchanges heat with the air flow resting on the tire outer surface3C located on the tire radial outer side of the circumferential projection315. As a result of these effects, a rise in temperature of the tire outer surface1dsof the tire side portion1dcan be suppressed, and the tire durability can be improved.

According to the tire1of the present embodiment, in the tire maximum width region TR, the projection outer end311is connected to the circumferential projection315, and the width of the circumferential projection315in the tire radial direction is narrower than the maximum width of the turbulence-generating projection310in the tire circumferential direction.

In a cross-section along the tire radial direction and the tire width direction, the tire outer surface1dsof the tire side portion1dhas a curved shape. Air flow having a radial component going outward in the tire radial direction thus easily separates from the tire outer surface1dsof the tire1near the tire maximum width region TR. In the tire maximum width region TR, however, the projection outer end311is connected to the circumferential projection315. Hence, when air flow with a radial component overcomes the circumferential projection315, the air flows in the vertical direction relative to the outer surface3C of the tire1(so-called downflow) at the outer side of the circumferential projection315in the tire radial direction. This suppresses the air flow that has a radial component from separating from the tire outer surface3C of the tire, controls the rise in temperature of the tire outer surface3C of the tire1on the outer side of the circumferential projection315in the tire radial direction, and improves the tire durability.

Furthermore, since the width of circumferential projection315in the tire radial direction is narrower than the maximum width of the turbulence-generating projection310in the tire circumferential direction, the amount of rubber material used to configured the tire side portion1ddoes not significantly increase. Therefore, the gauge of the tire side portion1dcan be made thinner, while the occurrence of bare portions in the projection outer end311is suppressed.

According to the tire1of the seventh embodiment, the turbulence-generating projection310extends at an inclination relative to the tire radial direction. Since the turbulence-generating projection310extends at an inclination relative to the tire radial direction, the generation of turbulence is promoted by the relationship between air flowing outward due to centrifugal force and stagnant air, thereby enhancing the cooling effect, as described in WO2009/017167.

INDUSTRIAL APPLICABILITY

A tire according to the present disclosure can be suitably used as any type of pneumatic tire, such as a passenger vehicle pneumatic tire and a truck/bus pneumatic tire.

REFERENCE SIGNS LIST