JP2014118011A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving a partial abrasion resistance performance.SOLUTION: The pneumatic tire 1 comprises, on a tread surface, at least three circumferential-directional main grooves 2 extending in the tire circumferential direction and a plurality of land portions 3 divided by the circumferential main grooves 2. An end land portion 3e of a belt disposed at the position in the tire width direction corresponding to an end portion outside in the tire width direction of a belt ply 144 at an outermost layer is a rib continuing in the tire circumferential direction. The end land portion 3e of the belt comprises a plurality of first sipes 41 at an edge portion inside in the tire width direction and a plurality of second sipes 42 at an edge portion outside in the tire width direction. Width W1 of the first sipes 41 and width W2 of the second sipes 42 have a relation of W2<W1.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve uneven wear resistance.

  In heavy duty pneumatic tires mounted on trucks, buses, etc., there is a problem that uneven wear generated on ribs in the tread portion should be suppressed. In particular, in a tire mounted on a steering shaft, uneven wear tends to appear, and thus higher uneven wear resistance is required. For this reason, the conventional pneumatic tire suppresses uneven wear of the ribs by arranging a plurality of sipes at the rib edge portions. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

Japanese Patent Laid-Open No. 2003-2014

  An object of the present invention is to provide a pneumatic tire capable of improving uneven wear resistance.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a carcass layer, a belt layer formed by laminating a plurality of belt plies and disposed on the outer side in the tire radial direction of the carcass layer, and A pneumatic tire including at least three circumferential main grooves extending in a tire circumferential direction and a plurality of land portions defined by the circumferential main grooves on a tread surface, the outermost tire in a tire width direction When the land portion that is in the same position in the tire width direction with respect to the end portion on the outer side in the tire width direction of the predetermined belt ply among the other land portions excluding the land portion in the area is referred to as a belt end land portion In addition, the belt end land portion is a rib continuous in the tire circumferential direction, and includes a plurality of first sipes at an inner edge portion in the tire width direction and a plurality of second sipes at an outer edge portion in the tire width direction. Prepare and before The width W1 of the first sipe, and the width W2 of the second sipes, characterized by having a relation of W2 <W1.

  In the pneumatic tire according to the present invention, since the width W1 of the first sipe and the width W2 of the second sipe have a relationship of W2 <W1, the rigidity of the edge portion on the outer side in the tire width direction of the belt end land portion is It becomes larger than the rigidity of the edge portion on the inner side in the width direction. Further, the left and right edge portions of the belt end land portion have a rigidity difference due to the positional relationship with the end portion of the belt ply described above. Therefore, when the width W1 of the first sipe and the width W2 of the second sipe have the above relationship, the rigidity difference between the left and right edge portions of the belt end land portion is alleviated. Thereby, there exists an advantage by which the partial wear of a belt edge land part is suppressed effectively.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged view showing the pneumatic tire depicted in FIG. 1. FIG. 3 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. FIG. 4 is an explanatory view showing a land portion of the pneumatic tire depicted in FIG. 3. FIG. 5 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. This figure shows one side region of a sectional view in the tire radial direction. The figure shows a heavy-duty radial tire mounted on a long-distance transport truck, bus or the like as an example of a pneumatic tire. In the figure, the symbol CL is the tire equator plane, and the symbol T is the tire ground contact end. The tire width direction means a direction parallel to a tire rotation axis (not shown), and the tire radial direction means a direction perpendicular to the tire rotation axis.

  The pneumatic tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. And a pair of sidewall rubbers 16 and 16 and a pair of rim cushion rubbers 17 and 17 (see FIG. 1).

  The pair of bead cores 11 and 11 is an annular member formed by bundling a plurality of bead wires, and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 includes a lower filler 121 and an upper filler 122, which are disposed on the tire radial direction outer periphery of the pair of bead cores 11 and 11, respectively, to reinforce the bead portion.

  The carcass layer 13 is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. Further, both ends of the carcass layer 13 are wound and locked from the inner side in the tire width direction to the outer side in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, nylon, polyester, rayon, etc.) with a coating rubber and rolling them, and has an absolute value of 85 [deg] or more and 95. [Deg] The following carcass angle (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction).

  The belt layer 14 is formed by laminating a plurality of belt plies 141 to 145, and is arranged around the outer periphery of the carcass layer 13. The belt layer 14 will be described later.

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of rim cushion rubbers 17 and 17 are arranged on the outer sides in the tire width direction of the left and right bead cores 11 and 11 and the bead fillers 12 and 12, respectively, and constitute left and right bead portions.

[Belt layer]
FIG. 2 is an enlarged view showing the pneumatic tire depicted in FIG. 1. This figure shows one side region of the tread portion with the tire equatorial plane CL as a boundary.

  The belt layer 14 is formed by laminating a high-angle belt 141, a pair of cross belts 142 and 143, a belt cover 144, and a circumferential reinforcing layer 145, and is arranged around the outer periphery of the carcass layer 13. (See FIG. 2).

  The high-angle belt 141 is formed by coating a plurality of belt cords made of steel or organic fiber material with a coating rubber and rolling the belt, and the belt has an absolute value of 40 [deg] or more and 70 [deg] or less with respect to the circumferential direction. An angle (an inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction). Further, the high-angle belt 141 is laminated and disposed on the outer side in the tire radial direction of the carcass layer 13.

  The pair of cross belts 142 and 143 is formed by rolling a plurality of belt cords made of steel or organic fiber material covered with a coat rubber, and has an absolute value of 10 [deg] or more and 45 [deg] with respect to the circumferential direction. It has the following belt angle. Further, the pair of cross belts 142 and 143 have belt angles with different signs from each other, and are laminated so that the fiber directions of the belt cords cross each other (cross-ply structure). Here, the cross belt 142 located on the inner side in the tire radial direction is called an inner diameter side cross belt, and the cross belt 143 located on the outer side in the tire radial direction is called an outer diameter side cross belt. Note that three or more cross belts may be laminated (not shown). In addition, the pair of cross belts 142 and 143 are disposed so as to be stacked on the outer side in the tire radial direction of the high-angle belt 141.

  The belt cover 144 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and the absolute value is 10 [deg] or more and 45 [deg] or less with respect to the circumferential direction. Has a belt angle. Further, the belt cover 144 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 142 and 143. In this embodiment, the belt cover 144 has the same belt angle as the outer diameter side crossing belt 143 and is disposed in the outermost layer of the belt layer 14.

  The circumferential reinforcing layer 145 is formed by spirally winding a steel belt cord covered with a coat rubber in the tire circumferential direction, and has a belt angle within a range of ± 5 [deg]. Further, the circumferential reinforcing layer 145 is disposed between the pair of cross belts 142 and 143. Further, the circumferential reinforcing layer 145 is disposed on the inner side in the tire width direction with respect to the left and right edge portions of the pair of cross belts 142 and 143. Specifically, one or more wires are spirally wound around the outer circumference of the inner diameter side crossing belt 142 to form the circumferential reinforcing layer 145. The circumferential reinforcing layer 145 reinforces the rigidity in the tire circumferential direction, so that the durability performance of the tire is improved.

  In this pneumatic tire 1, the belt layer 14 may have an edge cover (not shown). Generally, the edge cover is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and has an absolute value of a belt angle of 0 [deg] or more and 5 [deg] or less. Further, the edge covers are respectively disposed on the outer sides in the tire radial direction of the left and right edge portions of the outer diameter side cross belt 143 (or the inner diameter side cross belt 142). When these edge covers exhibit a tagging effect, the difference in diameter growth between the tread center region and the shoulder region is alleviated, and the uneven wear resistance performance of the tire is improved.

[Rib pattern]
FIG. 3 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. In the figure, the tire circumferential direction refers to the direction around the tire rotation axis. Moreover, the code | symbol T is a tire grounding end.

  The pneumatic tire 1 includes a plurality of circumferential main grooves 2 extending in the tire circumferential direction and a plurality of land portions 3 partitioned by the circumferential main grooves 2 in a tread portion (see FIG. 3). . For example, in the configuration of FIG. 3, the seven circumferential main grooves 2 are arranged symmetrically about the tire equatorial plane CL. The circumferential main grooves 2 define six rows of center land portions 3 and a pair of left and right shoulder land portions 3. All the land portions 3 are ribs that are continuous in the tire circumferential direction.

  The circumferential main groove 2 refers to a circumferential groove having a groove width of 5.0 [mm] or more. The groove width of the circumferential main groove 2 is measured excluding notches and chamfers formed in the groove opening of the tread surface. The circumferential main groove 2 may have a straight shape (see FIG. 3) or a wavy shape (not shown).

[Sipe of ribs]
In heavy duty pneumatic tires mounted on trucks, buses, etc., there is a problem that uneven wear generated on ribs in the tread portion should be suppressed. In particular, in a tire mounted on a steering shaft, uneven wear tends to appear, and thus higher uneven wear resistance is required. For this reason, the conventional pneumatic tire suppresses uneven wear of the ribs by arranging a plurality of sipes at the rib edge portions.

  By the way, there is a difference in rigidity between the inner region and the outer region in the tire width direction with this position as a boundary at the end portion of the predetermined belt ply in the tire width direction. For this reason, in the rib in this position, there is a problem in that a difference in rigidity occurs between the left and right edge portions in the tire width direction, and uneven wear such as rib punch and river wear is likely to occur.

  Therefore, this pneumatic tire 1 employs the following configuration in order to improve the uneven wear performance.

  FIG. 4 is an explanatory view showing a land portion of the pneumatic tire depicted in FIG. 3. The figure shows a land portion 3e at the same position in the tire width direction with respect to the end of the outermost belt ply (belt cover) 144, and a land portion 3s outside the tire width direction adjacent to the land portion 3e. Show.

  In this embodiment, among the plurality of land portions (center land portions) 3 partitioned into the circumferential main grooves, the same position in the tire width direction with respect to the end portion on the outer side in the tire width direction of the predetermined belt ply. The land portion 3e in the area is called a belt end land portion (see FIGS. 2 and 3).

  Examples of the predetermined belt ply include an outermost belt ply 144 and a circumferential reinforcing layer 145. (1) Since the outermost belt ply 144 is on the outermost side in the tire radial direction, a step is formed on the outer peripheral surface of the belt layer 14 by the end portion on the outer side in the tire width direction. Then, a rubber gauge difference of the tread rubber 15 occurs between the arrangement region of the belt ply 144 and other regions. For this reason, uneven wear tends to occur in the land portion 3e located at the same position with respect to the end portion of the belt ply 144. In addition, (2) the circumferential reinforcing layer 145 has a strong hoop effect, and therefore the arrangement region of the circumferential reinforcing layer 145 has higher rigidity than other regions. For this reason, uneven wear tends to occur in the land portion 3e located at the same position with respect to the end portion of the circumferential reinforcing layer 145.

  The positional relationship in the tire width direction between the land portion 3 and the end portion of the belt ply is determined as follows. That is, a perpendicular line is drawn from the bottom of the left and right circumferential main grooves 2 and 2 defining the land portion 3 to the belt layer, and if there is an end portion of the belt ply between these perpendicular lines, the land portion 3 and the belt ply Are determined to be at the same position in the tire width direction. In general, the end portion of the belt ply is disposed at a position deviated from directly below the circumferential main grooves 2 and 2 (above perpendicular line) in order to suppress the occurrence of groove cracks.

  In this pneumatic tire 1, as shown in FIGS. 2 and 3, the belt end land portion 3 e is a rib continuous in the tire circumferential direction, and is formed on the edge portion partitioned by the left and right circumferential main grooves 2, 2. And a plurality of sipes 41 and 42, respectively. Of these sipes 41 and 42, the sipe 41 at the inner edge in the tire width direction is referred to as a first sipe 41, and the sipe 42 at the outer edge in the tire width direction is referred to as a second sipe.

  The first sipe 41 and the second sipe 42 are arranged at predetermined intervals in the tire circumferential direction. By arranging these sipes 41 and 42 at the left and right edge portions of the belt end land portion 3e, rigidity of the edge portion of the belt end land portion 3e is reduced, and uneven wear of the belt end land portion 3e is suppressed. Is done.

  Further, the width W1 of the first sipe 41 and the width W2 of the second sipe 42 have a relationship of W2 <W1 (see FIG. 4). The widths W1 and W2 of the sipes 41 and 42 are the thicknesses of the gaps of the sipes 41 and 42, and are measured as the distance between the opposing sipe wall surfaces.

  In such a configuration, the rigidity of the edge portion on the outer side in the tire width direction of the belt end land portion 3e is larger than the rigidity of the edge portion on the inner side in the tire width direction. Further, as described above, the right and left edge portions of the belt end land portion 3e are caused by the positional relationship with the end portion of the outermost layer belt ply 144 (or the circumferential reinforcing layer 145), resulting in a difference in rigidity. Have Therefore, when the width W1 of the first sipe 41 and the width W2 of the second sipe 42 have the above relationship, the difference in rigidity between the left and right edge portions of the belt end land portion 3e is alleviated. Thereby, the uneven wear of the belt end land portion 3e is effectively suppressed.

  For example, in the configuration of FIG. 2, the center land portion 3 adjacent to the shoulder land portion 3 is at the same position in the tire width direction with respect to the end portion of the outermost belt ply 144 and the end portion of the circumferential reinforcing layer 145. There is a belt edge land.

  The center land portion 3 is the belt end land portion 3e if it is at the same position in the tire width direction with respect to either the end portion of the outermost belt ply 144 or the end portion of the circumferential reinforcing layer 145. It can be said. Therefore, even if the end of the outermost belt ply 144 or the end of the circumferential reinforcing layer 145 extends beyond the outer circumferential main groove 2 at the outermost side in the tire width direction and below the shoulder land portion 3. Good (not shown).

  Moreover, as shown in FIG. 3, all the land parts 3 are provided with the some sipes 41 and 42 in the edge part by the side of the circumferential direction main groove 2. As shown in FIG. Further, these sipes 41 and 42 are one-sided open sipes that open to the circumferential main groove 2 at one end and terminate in the land portion 3 at the other end. In addition, the sipes 41 and 42 are arranged at regular intervals in the tire circumferential direction (the number of tires arranged in the tire circumferential direction is equal), and have the same sipe length and the same sipe depth. In addition, the arrangement | positioning space | interval of each sipe 4, a sipe length, and a sipe depth can be set suitably.

  In the configuration of FIG. 3, only the wide first sipe 41 is disposed at the inner edge in the tire width direction of the belt edge land portion 3 e, and the second narrower edge is disposed at the outer edge in the tire width direction. Only the sipes 42 are arranged. As described above, the sipes 41 and 42 having different widths are respectively disposed on the left and right edge portions of the belt end land portion 3e over the entire circumference of the tire, so that uneven wear of the belt end land portion 3e is effective. To be suppressed.

  However, the present invention is not limited to this, and a wide first sipe 41 and a narrow second sipe 42 may be mixed and disposed on one edge portion (not shown). However, in order to obtain the above-described uneven wear suppression effect, it is necessary that the sipe group at the edge portion on the inner side in the tire width direction includes at least 40 [%] or more wide first sipe 41. Further, it is necessary that the first sipe 41 and the second sipe 42 are uniformly disposed over the entire tire circumference without being partially biased.

  In the above configuration, the width W1 of the first sipe 41 and the width W2 of the second sipe 42 preferably have a relationship of 1.5 ≦ W1 / W2 ≦ 2.0. The width W2 of the second sipe 42 is preferably in the range of 0.6 [mm] ≦ W2 ≦ 1.0 [mm]. Therefore, it is preferable that the width W1 of the first sipe 41 is in the range of 0.9 [mm] ≦ W1 ≦ 2.0 [mm]. Thereby, the width W1 of the first sipe 41 and the width W2 of the second sipe 42 are optimized.

  3 and 4, the land portion 3s on the outer side in the tire width direction adjacent to the belt end land portion 3e is a rib continuous in the tire circumferential direction, and a plurality of second portions are formed on the inner edge portion in the tire width direction. Three sipes 43 are provided. Further, it is preferable that the width W3 of the third sipe and the width W2 of the second sipe are substantially the same and have a relationship of 0.9 ≦ W3 / W2 ≦ 1.1.

  For example, in the configuration of FIGS. 3 and 4, the belt end land portion 3e and the shoulder land portion 3 (3s) are arranged adjacent to each other with the circumferential main groove 2 located on the outermost side in the tire width direction. Moreover, the edge part by the side of the circumferential direction main groove 2 of the belt end land part 3e has the narrow 2nd sipe 42. As shown in FIG. Further, the edge portion on the circumferential main groove 2 side of the shoulder land portion 3 s has a narrow third sipe 43 having substantially the same width as the second sipe 42. For this reason, the left and right edge portions sandwiching one circumferential main groove 2 are provided with sipes 42 and 43 having substantially the same width. Further, the edge portions of the land portions 3e and 3s located on the outer side in the tire width direction from the end portion of the belt ply 144 of the outermost layer are respectively provided with sipes 42 and 43 having a narrow width.

  Similarly, in the configuration of FIG. 3, the land portion 3 on the inner side in the tire width direction adjacent to the belt end land portion 3 e is also a rib continuous in the tire circumferential direction, and a plurality of sipes 4 are provided at the edge portion on the outer side in the tire width direction. I have. Further, the width of the sipe 4 and the width W1 of the first sipe 41 at the inner edge in the tire width direction of the belt end land portion 3e are substantially the same, and are 1.0 times or more and 1.1 times or less. Have the relationship. As a result, the left and right edge portions sandwiching one circumferential main groove 2 are provided with sipes 4 and 41 having substantially the same width, and the land located on the inner side in the tire width direction from the end portion of the outermost belt ply 144. The edge portions of the portions 3 and 3e are provided with wide sipes 4 and 41, respectively.

[effect]
As described above, the pneumatic tire 1 includes the carcass layer 13 and the belt layer 14 formed by laminating a plurality of belt plies 141 to 145 and disposed on the outer side in the tire radial direction of the carcass layer 13 ( (See FIG. 1). Further, the pneumatic tire 1 includes at least three circumferential main grooves 2 extending in the tire circumferential direction and a plurality of land portions 3 defined by the circumferential main grooves 2 on the tread surface ( (See FIG. 3). Further, of the other land portions 3 excluding the outermost land portion 3 in the tire width direction, a predetermined belt ply (for example, the outermost belt ply 144, the circumferential reinforcing layer 145, etc.) on the outer side in the tire width direction. The belt end land portion 3e located at the same position in the tire width direction with respect to the end portion is a rib continuous in the tire circumferential direction. Further, the belt end land portion 3e includes a plurality of first sipes 41 at an inner edge portion in the tire width direction, and includes a plurality of second sipes 42 at an outer edge portion in the tire width direction (see FIG. 4). Further, the width W1 of the first sipe 41 and the width W2 of the second sipe 42 have a relationship of W2 <W1.

  In such a configuration, since the width W1 of the first sipe 41 and the width W2 of the second sipe 42 have a relationship of W2 <W1, the rigidity of the edge portion on the outer side in the tire width direction of the belt end land portion 3e is determined in the tire width direction. It becomes larger than the rigidity of the inner edge part. Further, the left and right edge portions of the belt end land portion 3e have a rigidity difference due to the positional relationship with the end portion of the belt ply described above. Therefore, when the width W1 of the first sipe 41 and the width W2 of the second sipe 42 have the above relationship, the difference in rigidity between the left and right edge portions of the belt end land portion 3e is alleviated. Thereby, there exists an advantage by which the partial wear of the belt end land part 3e is suppressed effectively.

  In the pneumatic tire 1, the predetermined belt ply is the belt ply 144 that is the outermost in the tire radial direction among the plurality of belt plies 141 to 145 (see FIG. 2). Since the outermost belt ply 144 is on the outermost side in the tire radial direction, a step is formed on the outer peripheral surface of the belt layer 14 by the end portion on the outer side in the tire width direction. For this reason, a rubber gauge difference of the tread rubber 15 occurs between the arrangement region of the belt ply 144 and other regions. For this reason, uneven wear tends to occur in the land portion 3e located at the same position as the end of the belt ply 144. Therefore, when the belt end land portion 3e located at the same position as the outermost belt ply 144 has the above-described configuration, there is an advantage that the uneven wear suppressing effect of the belt end land portion 3e can be remarkably obtained.

  Further, in the pneumatic tire 1, the width W1 of the first sipe 41 and the width W2 of the second sipe 42 have a relationship of 1.5 ≦ W1 / W2 ≦ 2.0 (see FIG. 4). Thereby, there exists an advantage by which the relationship between the width W1 of the 1st sipe 41 and the width W2 of the 2nd sipe 42 is optimized. That is, when 1.5 ≦ W1 / W2, the effect of suppressing uneven wear at the edge portion of the belt end land portion 3e can be appropriately ensured. Moreover, it can suppress that the rigidity difference of the right-and-left edge part of the belt edge land part 3e becomes large too much because it is W1 / W2 <= 2.0.

  Moreover, in this pneumatic tire 1, the width W2 of the second sipe 42 is in the range of 0.6 [mm] ≦ W2 ≦ 1.0 [mm] (see FIG. 4). Therefore, the width W1 of the first sipe 41 is in the range of 0.9 [mm] ≦ W1 ≦ 2.0 [mm]. Thereby, there exists an advantage by which the width W1 of the 1st sipe 41 and the width W2 of the 2nd sipe 42 are optimized. That is, since 0.6 [mm] ≦ W2 (0.9 [mm] ≦ W1), the rigidity of the edge portion of the belt end land portion 3e is reduced, and uneven wear of the belt end land portion 3e is suppressed. Is done. Further, when W2 ≦ 1.0 [mm] (W1 ≦ 2.0 [mm]), the heel and toe wear of the rib due to the excessive sipe width is suppressed.

  Further, in this pneumatic tire 1, the land portion 3s on the outer side in the tire width direction adjacent to the belt end land portion 3e is a rib continuous in the tire circumferential direction, and a plurality of third sipes are formed on the inner edge portion in the tire width direction. 43 (see FIG. 3). Further, the width W3 of the third sipe 43 and the width W2 of the second sipe 42 are substantially the same (see FIG. 4). In such a configuration, since the left and right edge portions sandwiching one circumferential main groove 2 are provided with sipes 42 and 43 having substantially the same width, the rigidity of the edge portions of the ribs is reduced and the ground pressure is made uniform. There is an advantage that uneven wear of the rib is suppressed.

  In the pneumatic tire 1, the predetermined belt ply is a circumferential reinforcing layer 145 having a belt angle within a range of ± 5 [deg] with respect to the tire circumferential direction (see FIG. 2). Since the circumferential reinforcing layer 145 has a strong tagging effect, a difference in rigidity between the arrangement region of the circumferential reinforcing layer 145 and other regions is likely to occur. For this reason, uneven wear tends to occur in the land portion 3e located at the same position as the end portion of the circumferential reinforcing layer 145. Therefore, when the belt end land portion 3e located at the same position as the circumferential reinforcing layer 145 has the above-described configuration, there is an advantage that the effect of suppressing the uneven wear of the belt end land portion 3e is remarkably obtained.

  FIG. 5 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, evaluation about uneven wear resistance was performed for a plurality of different pneumatic tires (see FIG. 5). In this performance test, a pneumatic tire having a tire size of 295 / 75R22.5 is assembled to a standard rim, and 760 [kPa] and an additional load of 27.47 [kN] are applied to the pneumatic tire. Also, a pneumatic tire is mounted on a 6 × 4 truck steer shaft that is a test vehicle. Then, after the test vehicle has traveled 100,000 miles, a difference in the amount of wear at the left and right edge portions in the belt edge land portion 3e (see FIG. 3) is observed, and an evaluation based on the conventional example as a reference (100) is made. Done. This evaluation is preferable as the numerical value increases.

  The pneumatic tire 1 of Examples 1-8 has the structure described in FIGS. Further, the sipe 41, 42 on the left and right edge portions of the belt end land portion 3e and the sipe 43 of the shoulder land portion 3s have the same sipe interval, sipe length, and sipe depth.

  In the pneumatic tire of the conventional example, in the pneumatic tire of the first embodiment, the sipe 41 and 42 at the left and right edge portions of the belt end land portion 3e and the sipe 43 of the shoulder land portion 3s have the same sipe width. (Not shown).

  As shown in the test results, in the pneumatic tires of Examples 1 to 8, it can be seen that the uneven wear resistance performance is improved.

  1: pneumatic tire, 2: circumferential main groove, 3: land portion, 3e: belt end land portion, 4: sipe, 41: first sipe, 42: second sipe, 43: third sipe, 11: bead core , 12: Bead filler, 121: Lower filler, 122: Upper filler, 13: Carcass layer, 14: Belt layer, 141-145: Belt ply, 15: Tread rubber, 16: Side wall rubber, 17: Rim cushion rubber

Claims (6)

A carcass layer, a belt layer formed by laminating a plurality of belt plies and disposed on the outer side in the tire radial direction of the carcass layer, and at least three circumferential main grooves extending in the tire circumferential direction; A pneumatic tire comprising a plurality of land portions defined by the circumferential main grooves on a tread surface,
The land portion located at the same position in the tire width direction with respect to the end portion on the outer side in the tire width direction of the predetermined belt ply among the other land portions excluding the land portion on the outermost side in the tire width direction. When we call it the edge
The belt end land portion is a rib continuous in the tire circumferential direction, and includes a plurality of first sipes at the inner edge portion in the tire width direction, and a plurality of second sipes at the outer edge portion in the tire width direction, and,
The pneumatic tire according to claim 1, wherein a width W1 of the first sipe and a width W2 of the second sipe have a relationship of W2 <W1.   2. The pneumatic tire according to claim 1, wherein the predetermined belt ply is the belt ply on the outermost side in the tire radial direction among the plurality of belt plies.   The pneumatic tire according to claim 1 or 2, wherein a width W1 of the first sipe and a width W2 of the second sipe have a relationship of 1.5 ≦ W1 / W2 ≦ 2.0.   The pneumatic tire according to claim 3, wherein a width W2 of the second sipe is in a range of 0.6 [mm] ≦ W2 ≦ 1.0 [mm]. The land portion on the outer side in the tire width direction adjacent to the belt end land portion is a rib continuous in the tire circumferential direction, and includes a plurality of third sipes at the edge portion on the inner side in the tire width direction, and
The pneumatic tire according to any one of claims 1 to 4, wherein a width W3 of the third sipe and a width W2 of the second sipe are substantially the same.   The pneumatic tire according to claim 1, wherein the predetermined belt ply is a circumferential reinforcing layer having a belt angle within a range of ± 5 [deg] with respect to the tire circumferential direction.

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