Patent Description:
The present invention relates to heavy duty tires.

In order to manage data regarding manufacturing management, customer information, running history, etc., of tires, incorporation of radio frequency identification (RFID) tags into tires has been proposed. Various studies have been conducted for the technology to incorporate an RFID tag into a tire (for example <CIT>).

<CIT> discloses a heavy duty tire according to the preamble of claim <NUM>. Other related tires are disclosed in <CIT> and <CIT>.

From the viewpoint of preventing damage, an RFID tag is provided in a portion of a tire where the degree of bending is small. In the case of a heavy duty tire, each bead portion has high stiffness. In the heavy duty tire, the bead portion is effective as a location for placing the RFID tag.

A tire includes a carcass extending on and between a pair of beads. The carcass includes a carcass ply. The carcass ply is turned up around the beads. In the case of a heavy duty tire, each turned-up portion of the carcass ply is placed such that an end thereof overlaps an apex of the bead.

The carcass ply includes a large number of carcass cords aligned with each other. In a heavy duty tire, steel cords are used as the carcass cords. If the RFID tag is placed near metal components such as steel cords, there is a concern that radio waves may be disturbed.

In the heavy duty tire, if the RFID tag is set in the bead portion, from the viewpoint of ensuring a distance from metal components, it has been considered to place the RFID tag in a zone between the end of the turned-up portion and the end of the apex.

Meanwhile, an outer end of a chafer is located axially outward of the bead. The chafer extends radially outward from the rim side. The outer end of the chafer is a location where waving called creases is likely to occur in the manufacture of the tire. The creases may cause a reduction in durability and appearance quality of the tire.

The present invention has been made in view of such circumstances. An object of the present invention is to provide a heavy duty tire that can achieve formation of a good communication environment and reduction of the risk of damage to an RFID tag while suppressing occurrence of creases.

A heavy duty tire according to the present invention includes: a pair of beads; a carcass extending on and between the pair of beads; a pair of sidewalls each located axially outward of the carcass; a pair of chafers each located radially inward of the sidewall and configured to come into contact with a rim; and a tag member including an RFID tag. Each of the beads includes a core, an inner apex located radially outward of the core, and an outer apex located radially outward of the inner apex. The carcass includes a carcass ply, and the carcass ply includes a ply body extending between the pair of beads and a pair of turned-up portions each connected to the ply body and turned up around the bead. The tag member is in contact with the outer apex on a radially outer side of an end of the turned-up portion, the RFID tag is located between an outer end of the outer apex and an outer end of the chafer in a radial direction, and an outer end of the tag member is located radially outward of the outer end of the chafer. The outer end of the chafer is located radially outward of an inner end of the sidewall, and the sidewall covers the outer end of the chafer. An inner end of the tag member is located radially outward of the outer end of the chafer.

According to the present invention, a heavy duty tire that can achieve formation of a good communication environment and reduction of the risk of damage to an RFID tag while suppressing occurrence of creases, is obtained.

A tire of the present invention is fitted on a rim. The interior of the tire is filled with air to adjust the internal pressure of the tire. The tire fitted on the rim is also referred to as tire-rim assembly. The tire-rim assembly includes the rim and the tire fitted on the rim.

In the present invention, a state where a tire is fitted on a normal rim, the internal pressure of the tire is adjusted to a normal internal pressure, and no load is applied to the tire is referred to as a normal state.

In the present invention, unless otherwise specified, the dimensions and angles of each component of the tire are measured in the normal state.

The dimensions and angles of each component in a meridian cross-section of the tire, which cannot be measured in a state where the tire is fitted on the normal rim, are measured in a cut surface of the tire obtained by cutting the tire along a plane including the rotation axis of the tire. In this measurement, the tire is set such that the distance between right and left beads is made equal to the distance between the beads in the tire that is fitted on the normal rim. A component, of the tire, which cannot be confirmed in a state where the tire is fitted on the normal rim is confirmed in the above-described cut surface.

The normal rim means a rim specified in a standard on which the tire is based. The "standard rim" in the JATMA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are normal rims.

The normal internal pressure means an internal pressure specified in the standard on which the tire is based. The "highest air pressure" in the JATMA standard, the "maximum value" recited in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are normal internal pressures.

In the present invention, a tread portion of the tire is a portion of the tire that comes into contact with a road surface. A bead portion is a portion of the tire that is fitted to a rim. A sidewall portion is a portion of the tire that extends between the tread portion and the bead portion. The tire includes a tread portion, a pair of bead portions, and a pair of sidewall portions as portions thereof.

In the present invention, a complex elastic modulus of a component formed from a crosslinked rubber, from among the components included in the tire, is measured according to the standards of JIS K6394. The measurement conditions are as follows.

In this measurement, a test piece (a length of <NUM> × a width of <NUM> × a thickness of <NUM>) is sampled from the tire. The length direction of the test piece is caused to coincide with the circumferential direction of the tire. When a test piece cannot be sampled from the tire, a test piece is sampled from a sheet-shaped crosslinked rubber (hereinafter, also referred to as a rubber sheet) obtained by pressurizing and heating a rubber composition, which is used for forming the component to be measured, at a temperature of <NUM> for <NUM> minutes.

In the present invention, the complex elastic modulus is represented as a complex elastic modulus at <NUM>.

A heavy duty tire according to an aspect of the present invention includes: a pair of beads; a carcass extending on and between the pair of beads; a pair of sidewalls each located axially outward of the carcass; a pair of chafers each located radially inward of the sidewall and configured to come into contact with a rim; and a tag member including an RFID tag, wherein each of the beads includes a core, an inner apex located radially outward of the core, and an outer apex located radially outward of the inner apex, the carcass includes a carcass ply, the carcass ply includes a ply body extending between the pair of beads and a pair of turned-up portions each connected to the ply body and turned up around the bead, the tag member is in contact with the outer apex on a radially outer side of an end of the turned-up portion, the RFID tag is located between an outer end of the outer apex and an outer end of the chafer in a radial direction, and an outer end of the tag member is located radially outward of the outer end of the chafer.

By forming the tire as described above, the tag member is placed in the bead portion where the degree of bending is small. In the tire, the risk of damage to the RFID tag is low. In the tire, the outer apex is located between the carcass ply and the RFID tag. Since the RFID tag is placed so as to be spaced apart from the carcass ply, even if the carcass ply includes steel cords as carcass cords, radio waves are less likely to be disturbed. In the tire, a good communication environment is formed between the RFID tag and a communication device (not shown). Writing of data to the RFID tag and reading of data recorded in the RFID tag are accurately performed.

In the tire, the outer end of the tag member is located radially outward of the outer end of the chafer. Accordingly, interference between the outer end of the chafer and the tag member is suppressed as compared to the case where the outer end of the tag member is located radially inward of the outer end of the chafer. In the tire, occurrence of creases is suppressed.

The tire can achieve formation of a good communication environment and reduction of the risk of damage to the RFID tag while suppressing occurrence of creases.

According to the invention, in the tire described in [Configuration <NUM>] above, an inner end of the tag member is located radially outward of the outer end of the chafer.

By forming the tire as described above, interference between the tag member and the outer end of the chafer is effectively suppressed. In the tire, occurrence of creases is effectively suppressed.

According to the invention, in the tire described in [Configuration <NUM>] or [Configuration <NUM>] above, the outer end of the chafer is located radially outward of an inner end of the sidewall, and the sidewall covers the outer end of the chafer.

By forming the tire as described above, strain applied to the outer end of the chafer is effectively alleviated. In the tire, occurrence of damage starting from the outer end of the chafer is effectively suppressed.

Preferably, in the tire described in any one of [Configuration <NUM>] to [Configuration <NUM>] above, a ratio of a radial height of the outer end of the chafer to a radial height of the inner end of the sidewall is not less than <NUM> and not greater than <NUM>.

By forming the tire as described above, a region where the sidewall and the chafer are joined together can be sufficiently ensured. A space for placing the tag member is ensured, so that the tire allows the tag member to be placed at a position at which interference with the outer end of the chafer is less likely to occur. In the tire, occurrence of creases is effectively suppressed.

Preferably, in the tire described in any one of [Configuration <NUM>] to [Configuration <NUM>] above, a ratio of a radial height of the outer end of the outer apex to the radial height of the outer end of the chafer is not less than <NUM> and not greater than <NUM>.

By forming the tire as described above, the tire allows the tag member to be placed at a position at which interference with the outer end of the chafer is less likely to occur. In the tire, occurrence of creases is suppressed. The influence of the outer apex on bending of the tire is suppressed, so that good ride comfort is maintained with the tire.

Preferably, in the tire described in any one of [Configuration <NUM>] to [Configuration <NUM>] above, the tag member is provided on a side of a first sidewall out of the pair of sidewalls. By forming the tire as described above, the risk of occurrence of creases is reduced.

Preferably, in the tire described in any one of [Configuration <NUM>] to [Configuration <NUM>] above, the tag member is a plate-shaped member in which the RFID tag is covered with a crosslinked rubber, and the tag member has a thickness of not less than <NUM> and not greater than <NUM>.

By forming the tire as described above, the risk of damage to the RFID tag is reduced, and a good communication environment is formed.

Preferably, in the tire described in any one of [Configuration <NUM>] to [Configuration <NUM>] above, an outer end of the inner apex is located between the end of the turned-up portion and the RFID tag in the radial direction.

By forming the tire as described above, the inner apex effectively increases the stiffness of the bead portion. Strain applied to the RFID tag is effectively reduced. The tire can effectively reduce the risk of damage to the RFID tag.

<FIG> shows a part of a heavy duty tire <NUM> (hereinafter, also referred to simply as "tire <NUM>") according to an embodiment of the present invention. The tire <NUM> is mounted to a vehicle such as a truck and a bus.

In <FIG>, the tire <NUM> is fitted on a rim R (normal rim).

<FIG> shows a part of a cross-section (hereinafter, meridian cross-section) of the tire <NUM> along a plane including the rotation axis of the tire <NUM>. In <FIG>, the right-left direction is the axial direction of the tire <NUM>, and the up-down direction is the radial direction of the tire <NUM>. The direction perpendicular to the surface of the drawing sheet of <FIG> is the circumferential direction of the tire <NUM>.

<FIG> shows a part of the cross-section shown in <FIG>. <FIG> shows a bead portion of the tire <NUM>.

In <FIG>, an alternate long and short dash line CL extending in the radial direction represents the equator plane of the tire <NUM>. In <FIG> and <FIG>, a solid line BBL extending in the axial direction is a bead base line. The bead base line BBL is a line that defines the rim diameter (see JATMA or the like) of the rim R.

The tire <NUM> includes a tread <NUM>, a pair of sidewalls <NUM>, a pair of chafers <NUM>, a pair of beads <NUM>, a carcass <NUM>, a belt <NUM>, a pair of cushion layers <NUM>, a strip layer <NUM>, a pair of steel reinforcing layers <NUM>, a pair of interlayer strips <NUM>, an inner liner <NUM>, and a tag member <NUM>.

The tread <NUM> is located radially outward of the carcass <NUM>. The tread <NUM> comes into contact with a road surface at a tread surface <NUM> thereof. Grooves <NUM> are formed on the tread <NUM>.

The tread <NUM> includes a base portion <NUM> and a cap portion <NUM> located radially outward of the base portion <NUM>. The base portion <NUM> is formed from a crosslinked rubber that has low heat generation properties. The cap portion <NUM> is formed from a crosslinked rubber for which wear resistance and grip performance are taken into consideration. The cap portion <NUM> includes the tread surface <NUM>.

In <FIG>, a position indicated by reference sign PC corresponds to an equator. The equator PC is the point of intersection of the tread surface <NUM> and the equator plane CL. In the case where the groove <NUM> is located on the equator plane CL as in the tire <NUM>, the equator PC is specified on the basis of a virtual tread surface obtained on the assumption that the groove <NUM> is not present thereon.

The distance in the radial direction, from the bead base line BBL to the equator PC, obtained in the tire <NUM> in the normal state is the cross-sectional height (see JATMA or the like) of the tire <NUM>.

Each sidewall <NUM> is connected to an end of the tread <NUM>. The sidewall <NUM> is located radially inward of the tread <NUM>. The sidewall <NUM> is located axially outward of the carcass <NUM>. A position indicated by reference sign PS is an inner end of the sidewall <NUM>.

The sidewall <NUM> is formed from a crosslinked rubber for which cut resistance is taken into consideration. The complex elastic modulus of the sidewall <NUM> is not less than <NUM> MPa and not greater than <NUM> MPa.

A position indicated by reference sign PW is an axially outer end (hereinafter, outer end PW) of the tire <NUM>. In the case where decorations such as patterns and letters are present on the outer surface of the tire <NUM>, the outer end PW is specified on the basis of a virtual outer surface obtained on the assumption that the decorations are not present thereon. The tire <NUM> has a maximum width at the outer end PW. The outer end PW is also referred to as maximum width position.

The distance in the axial direction, from a first outer end PW to a second outer end PW (not shown), obtained in the tire <NUM> of the normal state is the cross-sectional width (see JATMA or the like) of the tire <NUM>.

In <FIG>, a length indicated by reference sign H is the distance in the radial direction from the bead base line BBL to the maximum width position PW. The distance H in the radial direction is also referred to as radial height of the maximum width position PW.

In the tire <NUM> in the normal state, the ratio of the radial height H of the maximum width position PW to the cross-sectional height is not less than <NUM> and not greater than <NUM>.

Each chafer <NUM> is located radially inward of the sidewall <NUM>. The chafer <NUM> comes into contact with the rim R. A position indicated by reference sign PB is an outer end of the chafer <NUM>.

The chafer <NUM> is formed from a crosslinked rubber for which wear resistance is taken into consideration. The complex elastic modulus of the chafer <NUM> is not less than <NUM> MPa and not greater than <NUM> MPa. The chafer <NUM> is harder than the sidewall <NUM>.

Each bead <NUM> is located axially inward of the chafer <NUM>. The bead <NUM> is located radially inward of the sidewall <NUM>. The bead <NUM> includes a core <NUM> and an apex <NUM>.

The core <NUM> extends in the circumferential direction. The core <NUM> includes a wound wire made of steel. The core <NUM> has a substantially hexagonal cross-sectional shape.

The apex <NUM> is located radially outward of the core <NUM>. The apex <NUM> extends radially outward from the core <NUM>. The apex <NUM> is tapered outward. An outer end PA of the apex <NUM> is located radially inward of the maximum width position PW. The outer end PA of the apex <NUM> is located radially outward of the outer end PB of the chafer <NUM>.

The apex <NUM> includes an inner apex <NUM> and an outer apex <NUM>. The inner apex <NUM> is located radially outward of the core <NUM>. The outer apex <NUM> is located radially outward of the inner apex <NUM>.

The inner apex <NUM> is tapered outward. The inner apex <NUM> is formed from a hard crosslinked rubber. The complex elastic modulus of the inner apex <NUM> is not less than <NUM> MPa and not greater than <NUM> MPa.

The outer apex <NUM> is thick around an outer end PU of the inner apex <NUM>. The outer apex <NUM> is tapered inward and tapered outward from the thick portion thereof.

An inner end PG1 of the outer apex <NUM> is located near the core <NUM>.

In <FIG>, a length indicated by reference sign L1 is the distance in the radial direction from the bead base line BBL to the outer end PG2 of the outer apex <NUM>. The distance L1 in the radial direction is also referred to as radial height of the outer end PG2 of the outer apex <NUM>. The outer end PG2 of the outer apex <NUM> is also the outer end PA of the apex <NUM>. The distance L1 in the radial direction is also referred to as radial height of the bead <NUM>.

In the tire <NUM>, from the viewpoint of well balancing the stiffness of the bead portion and bending of the tire <NUM>, the ratio (L1/H) of the radial height L1 of the bead <NUM> to the radial height H of the maximum width position PW is adjusted in the range of not less than <NUM> and not greater than <NUM>.

The outer apex <NUM> is formed from a crosslinked rubber. The outer apex <NUM> is more flexible than the inner apex <NUM>. The complex elastic modulus of the outer apex <NUM> is not less than <NUM> MPa and not greater than <NUM> MPa.

The outer apex <NUM> has stiffness substantially equal to the stiffness of the sidewall <NUM>, or is harder than the sidewall <NUM>.

The outer apex <NUM> is more flexible than the chafer <NUM>.

The apex <NUM> of the tire <NUM> further includes an edge strip <NUM>.

The edge strip <NUM> is located axially outward of the outer apex <NUM> and forms a part of the outer surface of the apex <NUM>. The edge strip <NUM> is located between the outer end PB of the chafer <NUM> and the inner end PG1 of the outer apex <NUM>.

The edge strip <NUM> is formed from a crosslinked rubber. The edge strip <NUM> is more flexible than the chafer <NUM> and is harder than the outer apex <NUM>. The complex elastic modulus of the edge strip <NUM> is not less than <NUM> MPa and not greater than <NUM> MPa.

The carcass <NUM> is located inward of the tread <NUM>, the pair of sidewalls <NUM>, and the pair of chafers <NUM>. The carcass <NUM> extends on and between the pair of beads <NUM>. The carcass <NUM> of the tire <NUM> has a radial structure.

The carcass <NUM> includes at least one carcass ply <NUM>. The carcass <NUM> of the tire <NUM> is composed of one carcass ply <NUM>. The carcass ply <NUM> is turned up around the beads <NUM>.

The carcass ply <NUM> has a ply body <NUM> and a pair of turned-up portions <NUM>. The ply body <NUM> extends between the pair of beads <NUM>, that is, between a first bead <NUM> and a second bead <NUM>. Each turned-up portion <NUM> is connected to the ply body <NUM> and turned up around the bead <NUM>. The turned-up portion <NUM> of the tire <NUM> is turned up around the bead <NUM> from the inner side toward the outer side in the axial direction. An end PF of the turned-up portion <NUM> is located radially inward of the outer end PB of the chafer <NUM>. The bead <NUM> is interposed between the ply body <NUM> and the turned-up portion <NUM>.

The carcass ply <NUM> includes a large number of carcass cords aligned with each other, which are not shown. These carcass cords are covered with a topping rubber. Each carcass cord intersects the equator plane CL. Steel cords are used as the carcass cords of the tire <NUM>.

In <FIG>, a length indicated by reference sign N is the distance in the radial direction from the bead base line BBL to the end PF of the turned-up portion <NUM>. The distance N in the radial direction is also referred to as radial height of the end PF of the turned-up portion <NUM>.

In the tire <NUM>, the ratio (N/H) of the radial height N of the end PF of the turned-up portion <NUM> to the radial height H of the maximum width position PW is not less than <NUM> and not greater than <NUM>.

The belt <NUM> includes four belt plies <NUM>. The four belt plies <NUM> are a first belt ply 54A, a second belt ply 54B, a third belt ply 54C, and a fourth belt ply 54D. These belt plies <NUM> are aligned in the radial direction.

In the tire <NUM>, the second belt ply 54B has a largest width, and the fourth belt ply 54D has a smallest width.

Each belt ply <NUM> includes a large number of belt cords aligned with each other, which are not shown. Each belt cord is tilted relative to the equator plane CL. Steel cords are used as the belt cords of the tire <NUM>.

Each cushion layer <NUM> is located between the belt <NUM> and the carcass <NUM> at the end of the belt <NUM>. The cushion layer <NUM> is formed from a flexible crosslinked rubber.

The strip layer <NUM> is located between the carcass <NUM> and the belt <NUM> on the radially inner side of the tread <NUM>. In the axial direction, the strip layer <NUM> is located between a first cushion layer <NUM> and a second cushion layer <NUM>. The strip layer <NUM> is formed from a crosslinked rubber.

Each steel reinforcing layer <NUM> is located in the bead portion. The steel reinforcing layer <NUM> is located between the chafer <NUM> and the carcass <NUM>. The steel reinforcing layer <NUM> is turned up around the bead <NUM>. The steel reinforcing layer <NUM> includes a large number of filler cords aligned with each other, which are not shown. The material of the filler cords is steel.

A first end 20f of the steel reinforcing layer <NUM> is located between the chafer <NUM> and the turned-up portion <NUM> in the axial direction. The first end 20f is located radially inward of the end PF of the turned-up portion <NUM>. A second end <NUM> of the steel reinforcing layer <NUM> is located between the inner liner <NUM> and the ply body <NUM> in the axial direction. It is sufficient that the position in the radial direction of the second end <NUM> substantially coincides with that of the first end 20f, and the second end <NUM> may be located radially outward of the first end 20f or may be located radially inward of the first end 20f.

Each interlayer strip <NUM> is located between the chafer <NUM> and the apex <NUM> of the bead <NUM> in the axial direction. The interlayer strip <NUM> covers the end PF of the turned-up portion <NUM> and the first end 20f of the steel reinforcing layer <NUM>.

The interlayer strip <NUM> is in contact with the apex <NUM> on the radially outer side of the end PF of the turned-up portion <NUM>. In other words, the contact surface between the interlayer strip <NUM> and the apex <NUM> forms a part of the outer surface of the apex <NUM>.

The interlayer strip <NUM> is in contact with the chafer <NUM> on the radially outer side of the first end 20f of the steel reinforcing layer <NUM>. In other words, the contact surface between the interlayer strip <NUM> and the chafer <NUM> forms a part of the inner surface of the chafer <NUM>.

The interlayer strip <NUM> is formed from a crosslinked rubber. The interlayer strip <NUM> is harder than the sidewall <NUM> and is more flexible than the chafer <NUM>. The complex elastic modulus of the interlayer strip <NUM> is not less than <NUM> MPa and not greater than <NUM> MPa.

The inner liner <NUM> is located inward of the carcass <NUM>. The inner liner <NUM> is joined to the inner surface of the carcass <NUM> via an insulation (not shown) formed from a crosslinked rubber. The inner liner <NUM> forms an inner surface of the tire <NUM>. The inner liner <NUM> is formed from a crosslinked rubber that has an excellent air blocking property.

The tag member <NUM> is located axially outward of the bead <NUM>. In the tire <NUM>, the tag member <NUM> is provided only on the side of a first sidewall <NUM>. The tag member <NUM> may be provided on each of the side of the first sidewall <NUM> and the side of a second sidewall <NUM>. From the viewpoint of reducing occurrence of creases, the tag member <NUM> is preferably provided on the side of the first sidewall <NUM> out of the pair of sidewalls <NUM>.

<FIG> is a plan view of the tag member <NUM>. <FIG> is a cross-sectional view taken along a line IV-IV in <FIG>.

The tag member <NUM> has a plate shape. The tag member <NUM> is long in a length direction thereof and short in a width direction thereof. As shown in <FIG>, in the tire <NUM>, the tag member <NUM> is placed such that a first end <NUM> in the width direction thereof is located on the radially outer side in the tire <NUM> and a second end 26u in the width direction thereof is located on the radially inner side in the tire <NUM>.

The tag member <NUM> includes an RFID tag <NUM>. In <FIG>, for convenience of description, the RFID tag <NUM> is shown by a solid line, but the entirety thereof is covered with a protector <NUM>. The tag member <NUM> includes the RFID tag <NUM> and the protector <NUM>. The RFID tag <NUM> is located at the center of the tag member <NUM>. The protector <NUM> is formed from a crosslinked rubber. The protector <NUM> has stiffness substantially equal to the stiffness of the outer apex <NUM>. In the tire <NUM>, formation of a good communication environment is considered, and a crosslinked rubber having high electrical resistance is used for the protector <NUM>. The protector <NUM> is formed from a rubber that has high insulation properties.

Although not described in detail, the RFID tag <NUM> is a small and lightweight electronic component that includes: a semiconductor chip <NUM> obtained by making a transmitter/receiver circuit, a control circuit, a memory, etc., into a chip; and an antenna <NUM>. Upon receiving interrogation radio waves, the RFID tag <NUM> uses the radio waves as electrical energy and transmits various data in the memory as response radio waves. The RFID tag <NUM> is a type of passive radio frequency identification transponder.

In the tire <NUM>, the tag member <NUM> is a plate-shaped member in which the RFID tag <NUM> is covered with a crosslinked rubber. From the viewpoint of reducing the risk of damage to the RFID tag <NUM> and forming a good communication environment, the thickness of the tag member <NUM> in the tire <NUM> is preferably not less than <NUM> and not greater than <NUM>. The thickness of the tag member <NUM> in the tire <NUM> is represented as the maximum thickness of the tag member <NUM> at the semiconductor chip <NUM> of the RFID tag <NUM>.

A length TL of the tag member <NUM> before embedding in the tire <NUM> is not less than <NUM> and not greater than <NUM>. A width TW thereof is not less than <NUM> and not greater than <NUM>.

The position of the RFID tag <NUM> in the tire <NUM> is represented as the position of a radially inner end of the RFID tag <NUM> (specifically, the semiconductor chip <NUM>) in the meridian cross-section of the tire <NUM>. In <FIG>, a position indicated by reference sign TU is the radially inner end of the RFID tag <NUM> as the position of the RFID tag <NUM> in the tire <NUM>.

In the tire <NUM>, the tag member <NUM> is located axially outward of the outer apex <NUM> on the radially outer side of the end PF of the turned-up portion <NUM>. The tag member <NUM> is in contact with the outer apex <NUM>. The boundary between the tag member <NUM> and the outer apex <NUM> forms a part of the outer surface of the outer apex <NUM>. In other words, the boundary between the tag member <NUM> and the outer apex <NUM> forms a part of the outer surface of the apex <NUM>.

In the tire <NUM>, the RFID tag <NUM> is located between the outer end PG2 of the outer apex <NUM> and the outer end PB of the chafer <NUM> in the radial direction.

The RFID tag <NUM> of the tire <NUM> is placed in the bead portion where the degree of bending is small. In the tire <NUM>, the risk of damage to the RFID tag <NUM> is low.

In the tire <NUM>, the outer apex <NUM> is located between the carcass ply <NUM> and the RFID tag <NUM>. The RFID tag <NUM> is placed so as to be spaced apart from the carcass ply <NUM> including the carcass cords which are metal components. Radio waves are less likely to be disturbed, so that a good communication environment is formed between the RFID tag <NUM> and a communication device (not shown). Writing of data to the RFID tag <NUM> and reading of data recorded in the RFID tag <NUM> are accurately performed.

Meanwhile, the outer end PB of the chafer <NUM> is located axially outward of the bead <NUM>. The chafer <NUM> is a component extending radially outward from the rim R side. The outer end PB of the chafer <NUM> is a location where waving called creases is likely to occur in the manufacture of the tire <NUM>. Since the tag member <NUM> is placed near the outer end PB of the chafer <NUM>, there is a concern that creases may occur depending on the degree of interference between the outer end PB of the chafer <NUM> and the tag member <NUM>.

In the tire <NUM>, the outer end <NUM> of the tag member <NUM> is located radially outward of the outer end PB of the chafer <NUM>. In the tire <NUM>, interference between the outer end PB of the chafer <NUM> and the tag member <NUM> is suppressed as compared to the case where the outer end <NUM> of the tag member <NUM> is located radially inward of the outer end PB of the chafer <NUM> (i.e., the case where the entirety of the tag member <NUM> is covered with the chafer <NUM>). In the tire <NUM>, creases which influence durability and appearance quality are less likely to occur.

The tire <NUM> can achieve formation of a good communication environment and reduction of the risk of damage to the RFID tag <NUM> while suppressing occurrence of creases.

In the tire <NUM>, the inner end 26u of the tag member <NUM> is located radially outward of the outer end PB of the chafer <NUM>. Accordingly, the entirety of the tag member <NUM> is placed radially outward of the outer end PB of the chafer <NUM>. Interference between the tag member <NUM> and the outer end PB of the chafer <NUM> is effectively suppressed. In the tire <NUM>, occurrence of creases is effectively suppressed. From this viewpoint, in the tire <NUM>, the inner end 26u of the tag member <NUM> is preferably located radially outward of the outer end PB of the chafer <NUM>.

In the tire <NUM>, the outer end <NUM> of the tag member <NUM> is located radially inward of the outer end PG2 of the outer apex <NUM>. Accordingly, the influence of the tag member <NUM> on bending of the sidewall portion is effectively suppressed. With the tire <NUM>, good durability and ride comfort are maintained. From this viewpoint, the outer end <NUM> of the tag member <NUM> is preferably located radially inward of the outer end PG2 of the outer apex <NUM>.

In the tire <NUM>, more preferably, the inner end 26u of the tag member <NUM> is located radially outward of the outer end PB of the chafer <NUM>, and the outer end <NUM> of the tag member <NUM> is located radially inward of the outer end PG2 of the outer apex <NUM>. In this case, as shown in <FIG>, the entirety of the tag member <NUM> is placed between the outer end PG2 of the outer apex <NUM> and the outer end PB of the chafer <NUM>.

In the tire <NUM>, the outer end PB of the chafer <NUM> is located radially outward of the inner end PS of the sidewall <NUM>, and the sidewall <NUM> covers the outer end PB of the chafer <NUM>. Since the outer end PB of the chafer <NUM> is covered with the sidewall <NUM>, strain applied to the outer end PB is effectively alleviated. In the tire <NUM>, the chafer <NUM> is harder than the sidewall <NUM>. Therefore, by covering the outer end PB of the chafer <NUM> with the sidewall <NUM>, strain applied to the outer end PB is more effectively alleviated. In the tire <NUM>, occurrence of damage starting from the outer end PB of the chafer <NUM> is effectively suppressed. From this viewpoint, in the tire <NUM>, preferably, the outer end PB of the chafer <NUM> is located radially outward of the inner end PS of the sidewall <NUM>, and the sidewall <NUM> covers the outer end PB of the chafer <NUM>.

In <FIG>, a length indicated by reference sign R1 is the distance in the radial direction from the bead base line BBL to the outer end PB of the chafer <NUM>. The distance R1 in the radial direction is also referred to as radial height of the outer end PB of the chafer <NUM>.

In <FIG>, a length indicated by reference sign K2 is the distance in the radial direction from the bead base line BBL to the inner end PS of the sidewall <NUM>. The distance K2 in the radial direction is also referred to as radial height of the inner end PS of the sidewall <NUM>.

In the tire <NUM>, the ratio (R1/K2) of the radial height R1 of the outer end PB of the chafer <NUM> to the radial height K2 of the inner end PS of the sidewall <NUM> is not less than <NUM> and not greater than <NUM>.

When the ratio (R1/K2) is set to be not less than <NUM>, a region where the sidewall <NUM> and the chafer <NUM> are joined together can be sufficiently ensured. In the tire <NUM>, occurrence of creases is effectively suppressed. From this viewpoint, the ratio (R1/K2) is more preferably not less than <NUM>.

When the ratio (R1/K2) is set to be not greater than <NUM>, a space for placing the tag member <NUM> is ensured. The tire <NUM> allows the tag member <NUM> to be placed at a position at which interference with the outer end PB of the chafer <NUM> is less likely to occur. In the tire <NUM>, occurrence of creases is suppressed. From this viewpoint, the ratio (R1/K2) is more preferably not greater than <NUM>.

In the tire <NUM>, the ratio (L1/R1) of the radial height L1 of the outer end PG2 of the outer apex <NUM> to the radial height R1 of the outer end PB of the chafer <NUM> is preferably not less than <NUM> and not greater than <NUM>.

When the ratio (L1/R1) is set to be not less than <NUM>, a space for placing the tag member <NUM> is ensured. The tire <NUM> allows the tag member <NUM> to be placed at a position at which interference with the outer end PB of the chafer <NUM> is less likely to occur. In the tire <NUM>, occurrence of creases is suppressed. From this viewpoint, the ratio (L1/R1) is more preferably not less than <NUM>.

When the ratio (L1/R1) is set to be not greater than <NUM>, the influence of the outer apex <NUM> on bending of the tire <NUM> is suppressed. With the tire <NUM>, good ride comfort is maintained. From this viewpoint, the ratio (L1/R1) is more preferably not greater than <NUM>.

In the tire <NUM>, the outer end PU of the inner apex <NUM> is located between the end PF of the turned-up portion <NUM> and the RFID tag <NUM> in the radial direction. Accordingly, the hard inner apex <NUM> effectively increases the stiffness of the bead portion. Strain applied to the RFID tag <NUM> is effectively reduced. The tire <NUM> can effectively reduce the risk of damage to the RFID tag <NUM>. From this viewpoint, the outer end PU of the inner apex <NUM> is preferably located between the end PF of the turned-up portion <NUM> and the RFID tag <NUM> in the radial direction. In this case, from the viewpoint of being able to further reduce the risk of damage to the RFID tag <NUM>, more preferably, the outer end PU of the inner apex <NUM> is located between the end PF of the turned-up portion <NUM> and the RFID tag <NUM> in the radial direction, and further, the outer end PU of the inner apex <NUM> is located between the end PF of the turned-up portion <NUM> and the outer end PB of the chafer <NUM> in the radial direction.

As is obvious from the above description, according to the present invention, the heavy duty tire <NUM> that can achieve formation of a good communication environment and reduction of the risk of damage to the RFID tag <NUM> while suppressing occurrence of creases, is obtained.

The following will describe the present invention in further detail by means of examples, etc., but the present invention is not limited to these examples.

Heavy duty tires (tire size = <NUM>/70R22. <NUM>) having the basic structure shown in <FIG> and having specifications shown in Table <NUM> below were obtained.

The radial height L1 of the outer end of the outer apex was set to <NUM>. The radial height R1 of the outer end of the chafer was set to <NUM>. The radial height K2 of the inner end of the sidewall was set to <NUM>.

The tag member was set so as to be in contact with the outer surface of the apex. In particular, the tag member was set in a zone, between the outer end of the outer apex and the end of the turned-up portion, where strain applied to the RFID tag was small and a good communication environment was formed.

Examples <NUM> and <NUM> and Comparative Example <NUM> were prepared by changing the position of the tag member. In each case, the outer end of the tag member was located radially inward of the outer end of the outer apex.

In Example <NUM>, the tag member was placed such that the entirety thereof was located between the outer end of the outer apex and the outer end of the chafer. The fact that the outer end and the inner end of the tag member are located radially outward of the outer end of the chafer is represented as "out" in the cells for outer end and inner end in Table <NUM>.

In Example <NUM>, the outer end of the tag member was located radially outward of the outer end of the chafer, and the inner end of the tag member was located radially inward of the outer end of the chafer. This is represented as "out" in the cell for outer end and as "in" in the cell for inner end in Table <NUM>.

The RFID tag was placed radially outward of the outer end of the chafer.

In Comparative Example <NUM>, the tag member was placed such that the entirety thereof was located between the outer end of the chafer and the end of the turned-up portion. The fact that the outer end and the inner end of the tag member are located radially inward of the outer end of the chafer is represented as "in" in the cells for outer end and inner end in Table <NUM>.

A cross-section of the bead portion of a test tire was cut out to check the state of occurrence of creases. The state of occurrence of creases was evaluated on a <NUM>-point scale with the case where no creases occurred being regarded as rank <NUM> and with the state of occurrence of creases of Comparative Example <NUM> being regarded as rank <NUM>. The acceptance criterion was defined as being rank <NUM> or lower.

As shown in Table <NUM>, it is confirmed that occurrence of creases is suppressed in each Example. From the evaluation results, advantages of the present invention are clear.

Claim 1:
A heavy duty tire (<NUM>) comprising:
a pair of beads (<NUM>);
a carcass (<NUM>) extending on and between the pair of beads (<NUM>);
a pair of sidewalls (<NUM>) each located axially outward of the carcass (<NUM>);
a pair of chafers (<NUM>) each located radially inward of the sidewall (<NUM>) and configured to come into contact with a rim (R); and
a tag member (<NUM>) including an RFID tag (<NUM>), wherein
each of the beads (<NUM>) includes a core (<NUM>), an inner apex (<NUM>) located radially outward of the core (<NUM>), and an outer apex (<NUM>) located radially outward of the inner apex (<NUM>),
the carcass (<NUM>) includes a carcass ply (<NUM>),
the carcass ply (<NUM>) includes a ply body (<NUM>) extending between the pair of beads (<NUM>) and a pair of turned-up portions (<NUM>) each connected to the ply body (<NUM>) and turned up around the bead (<NUM>),
the tag member (<NUM>) is in contact with the outer apex (<NUM>) on a radially outer side of an end (PF) of the turned-up portion (<NUM>),
the RFID tag (<NUM>) is located between an outer end (PG2) of the outer apex (<NUM>) and an outer end (PB) of the chafer (<NUM>) in a radial direction,
an outer end (<NUM>) of the tag member (<NUM>) is located radially outward of the outer end (PB) of the chafer (<NUM>),
the outer end (PB) of the chafer (<NUM>) is located radially outward of an inner end (PS) of the sidewall (<NUM>), and
the sidewall (<NUM>) covers the outer end (PB) of the chafer (<NUM>),
characterized in that an inner end (26u) of the tag member (<NUM>) is located radially outward of the outer end (PB) of the chafer (<NUM>).