JP7196508B2 - pneumatic tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving tear resistance performance of the tire.

Heavy-duty tires, especially tires for garbage trucks that run on city roads under high-load conditions, have the problem of rib tears occurring due to running over curbs and protrusions on the road. As a conventional pneumatic tire related to such problems, the technique described in Patent Document 1 is known.

JP 2018-8586 A

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

In order to achieve the above object, a pneumatic tire according to the present invention includes a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove, A groove opening and a groove bottom of the circumferential main groove each have a zigzag shape or a wavy shape with amplitude in the tire width direction, and are located outside in the tire width direction at each of the groove opening and the groove bottom. An outer edge portion is defined, an outer maximum amplitude position that is convex outward in the tire width direction and an inner maximum amplitude position that is convex inward in the outer edge portion are defined, and the outer edge portion of the groove opening is defined. The outer maximum amplitude position is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the outer edge portion of the corresponding groove bottom, and the outer maximum amplitude position at the outer edge portion of the groove bottom is arranged. The maximum distance L2o in the tire circumferential direction between the amplitude position and the inner maximum amplitude position has a relationship of 0.55≦L2o/λ2o≦0.65 with respect to the wavelength λ2o of the outer edge portion of the groove bottom . Characterized by

Further, a pneumatic tire according to the present invention is a pneumatic tire including a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove, wherein the circumferential main groove Each of the groove opening and the groove bottom has a zigzag shape or a wavy shape with amplitude in the tire width direction, and the center line of each of the groove opening and the groove bottom is convex outward in the tire width direction. and an inwardly convex inner maximum amplitude position, wherein the outer maximum amplitude position of the center line of the groove opening corresponds to the outer maximum amplitude position of the center line of the groove bottom and the maximum distance L2c in the tire circumferential direction between the outer maximum amplitude position and the inner maximum amplitude position on the center line of the groove bottom is equal to the It is characterized by having a relationship of 0.55≦L2c/λ2c≦0.65 with respect to the wavelength λ2c of the center line .
Further, a pneumatic tire according to the present invention is a pneumatic tire including a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove, wherein the circumferential main groove Each of the groove opening and the groove bottom has a zigzag or wavy shape with amplitude in the tire width direction, and each of the groove opening and the groove bottom defines an outer edge portion on the outside in the tire width direction Then, an outer maximum amplitude position that is convex outward in the tire width direction and an inner maximum amplitude position that is convex inward in the outer edge portion are defined, and the outer maximum amplitude position of the outer edge portion of the groove opening is defined. is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the outer edge portion of the corresponding groove bottom portion, and the wavelength λ1o of the outer edge portion of the groove opening is equal to the groove bottom portion 0.95≤λ2o/λ1o≤1.10 with respect to the wavelength λ2o of the outer edge portion.
Further, a pneumatic tire according to the present invention is a pneumatic tire including a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove, wherein the circumferential main groove Each of the groove opening and the groove bottom has a zigzag shape or a wavy shape with amplitude in the tire width direction, and the center line of each of the groove opening and the groove bottom is convex outward in the tire width direction. and an inwardly convex inner maximum amplitude position, wherein the outer maximum amplitude position of the center line of the groove opening corresponds to the outer maximum amplitude position of the center line of the groove bottom , and the wavelength λ1c of the center line of the groove opening is 0.95 ≤ λ2c/λ1c ≤ 1 with respect to the wavelength λ2c of the center line of the groove bottom .10 relationship.
Further, a pneumatic tire according to the present invention is a pneumatic tire including a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove, wherein the circumferential main groove Each of the groove opening and the groove bottom has a zigzag or wavy shape with amplitude in the tire width direction, and each of the groove opening and the groove bottom defines an outer edge portion on the outside in the tire width direction Then, an outer maximum amplitude position that is convex outward in the tire width direction and an inner maximum amplitude position that is convex inward in the outer edge portion are defined, and the outer maximum amplitude position of the outer edge portion of the groove opening is defined. is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the outer edge portion of the corresponding groove bottom portion, and the pitch number of the outer edge portion of the groove opening is equal to the groove bottom portion is equal to the number of pitches of the outer edge portion of .
Further, a pneumatic tire according to the present invention is a pneumatic tire including a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove, wherein the circumferential main groove Each of the groove opening and the groove bottom has a zigzag shape or a wavy shape with amplitude in the tire width direction, and the center line of each of the groove opening and the groove bottom is convex outward in the tire width direction. and an inwardly convex inner maximum amplitude position, wherein the outer maximum amplitude position of the center line of the groove opening corresponds to the outer maximum amplitude position of the center line of the groove bottom and the number of pitches of the centerlines of the groove openings is equal to the number of pitches of the centerlines of the groove bottoms.

In the pneumatic tire according to the present invention, the outer maximum amplitude position of the outer edge portion of the groove bottom of the shoulder main groove is offset in the tire circumferential direction with respect to the position where the ground contact width of the shoulder land portion is minimum. Therefore, the rigidity of the groove wall of the shoulder land portion is three-dimensionally reinforced, compared to a structure in which the outer maximum amplitude positions of the groove opening portion and the groove bottom portion are at the same position in the tire circumferential direction. As a result, there is an advantage that the tearing of the shoulder land portion is suppressed and the tear resistance performance of the tire is improved.

FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the invention taken along the tire meridian line. 2 is a plan view showing the tread surface of the pneumatic tire shown in FIG. 1. FIG. FIG. 3 is an explanatory diagram showing the groove wall structure of the circumferential main groove shown in FIG. FIG. 4 is an explanatory view showing the groove wall structure of the circumferential main groove shown in FIG. FIG. 5 is an explanatory diagram showing the groove wall structure of the circumferential main groove shown in FIG. FIG. 6 is an explanatory diagram showing the inner edge portion of the shoulder main groove shown in FIG. FIG. 7 is an explanatory diagram showing the groove wall structure of the circumferential main groove shown in FIG. FIG. 8 is an explanatory diagram showing the shoulder main groove shown in FIG. 9 is an explanatory view showing the center main groove shown in FIG. 7. FIG. FIG. 10 is a chart showing results of performance tests of the pneumatic tire according to the embodiment of the invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious to replace. Moreover, the multiple modifications described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the invention taken along the tire meridian line. This figure shows a cross-sectional view of one side area in the tire radial direction. In addition, the figure shows a heavy-duty tire mounted on a garbage truck as an example of a pneumatic tire.

In the figure, the cross section in the tire meridian direction refers to a cross section when the tire is cut along a plane including the tire rotation axis (not shown). Further, the symbol CL is the tire equatorial plane, which is a plane perpendicular to the tire rotation axis passing through the center point of the tire in the tire rotation axis direction. Moreover, the tire width direction refers to the direction parallel to the tire rotation axis, and the tire radial direction refers to the direction perpendicular to the tire rotation axis.

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

A pair of bead cores 11, 11 are formed by winding one or a plurality of steel bead wires in a ring-shaped manner, and are embedded in the bead portions to constitute the cores of the left and right bead portions. The pair of bead fillers 12, 12 are arranged on the tire radial direction outer peripheries of the pair of bead cores 11, 11, respectively, to reinforce the bead portions.

The carcass layer 13 has a single layer structure consisting of one carcass ply or a multilayer structure consisting of a plurality of laminated carcass plies. configure. Further, both ends of the carcass layer 13 are wound back outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12 and are locked. The carcass plies of the carcass layer 13 are formed by coating a plurality of carcass cords made of steel or organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coating rubber and rolling them. It has a carcass angle (defined as an inclination angle of the longitudinal direction of the carcass cords with respect to the tire circumferential direction) of [deg] or more and 100 [deg] or less.

The belt layer 14 is formed by laminating a pair of cross belts 141 and 142, and is placed around the outer periphery of the carcass layer 13. As shown in FIG. The pair of cross belts 141 and 142 is constructed by coating a plurality of belt cords made of steel or organic fiber material with coat rubber and rolling the cords. have. The pair of cross belts 141 and 142 have belt angles of opposite signs (defined as inclination angles of the longitudinal direction of the belt cords with respect to the tire circumferential direction), and the longitudinal directions of the belt cords intersect each other. laminated together (so-called cross-ply structure).

The tread rubber 15 is arranged on the outer periphery of the carcass layer 13 and the belt layer 14 in the tire radial direction to constitute the tread portion of the tire. A pair of sidewall rubbers 16, 16 are arranged outside the carcass layer 13 in the tire width direction, respectively, and constitute left and right sidewall portions. The pair of rim cushion rubbers 17, 17 extend from the inner side in the tire radial direction to the outer side in the tire width direction of the turn-up portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute rim fitting surfaces of the bead portions.

[Tread pattern]
2 is a plan view showing the tread surface of the pneumatic tire shown in FIG. 1. FIG. The figure shows the tread surface of an all-position tire that can run on-road and off-road. In the figure, the tire circumferential direction refers to the direction around the tire rotation axis. Further, reference character T is a tire contact edge, and dimension symbol TW is a tire contact width.

As shown in FIG. 2, the pneumatic tire 1 includes a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction, a plurality of land portions 31 partitioned by the circumferential main grooves 21 and 22, 32, 33 are provided on the tread surface.

The main groove is a groove required to display a wear indicator defined by JATMA, and has a maximum groove width of 7.0 [mm] or more and a maximum groove depth of 12 [mm] or more.

The groove width is measured as the distance between the left and right groove walls at the opening of the groove in a no-load state in which the tire is mounted on a specified rim and filled with a specified internal pressure. In a configuration in which the land portion has a notch portion or a chamfered portion at the edge portion, the groove width is measured by using the intersection of the tread surface and the extension line of the groove wall as a measurement point in a cross-sectional view with the groove length direction as the normal direction. is measured.

Groove depth is measured as the distance from the tread surface to the bottom of the groove when the tire is mounted on a specified rim and filled with a specified internal pressure in an unloaded state. In addition, in a configuration in which the groove has partial irregularities or sipes at the groove bottom, the groove depth is measured excluding these.

A specified rim means a "standard rim" specified by JATMA, a "design rim" specified by TRA, or a "measuring rim" specified by ETRTO. In addition, the prescribed internal pressure means the "maximum air pressure" prescribed by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" prescribed by TRA, or "INFLATION PRESSURES" prescribed by ETRTO. Moreover, the specified load means the "maximum load capacity" specified by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO. However, according to JATMA, in the case of passenger car tires, the specified internal pressure is 180 [kPa], and the specified load is 88 [%] of the maximum load capacity at the specified internal pressure.

For example, in the configuration of FIG. 2, the pneumatic tire 1 has a substantially point-symmetrical tread pattern with the center point on the tire equatorial plane CL. However, the present invention is not limited to this, and the pneumatic tire 1 may have, for example, a symmetrical tread pattern centered on the tire equatorial plane CL or an asymmetrical tread pattern. (illustration omitted).

In addition, in the configuration of FIG. 2 , the left and right regions bounded by the tire equatorial plane CL each have two circumferential main grooves 21 and 22 . Further, these circumferential main grooves 21 and 22 are arranged symmetrically with respect to the tire equatorial plane CL. Five rows of land portions 31 to 33 are defined by these circumferential main grooves 21 and 22 . One land portion 33 is arranged on the tire equatorial plane CL.

However, not limited to this, three or five or more circumferential main grooves may be arranged, or the circumferential main grooves may be arranged asymmetrically with respect to the tire equatorial plane CL (not shown). . Also, by arranging one circumferential main groove on the tire equatorial plane CL, the land portion may be arranged at a position deviated from the tire equatorial plane CL (not shown).

In addition, of the circumferential main grooves 21 and 22 arranged in one region bounded by the tire equatorial plane CL, the outermost circumferential main groove 21 in the tire width direction is defined as the shoulder main groove, and the tire equator. The circumferential main groove 22 on the surface CL side is defined as a center main groove.

For example, in the configuration of FIG. 2, the distance Dg1 from the tire equatorial plane CL to the groove center lines of the left and right shoulder main grooves 21, 21 is in the range of 26% or more and 32% or less of the tire contact width TW. . Also, the distance Dg2 from the tire equatorial plane CL to the groove center lines of the left and right center main grooves 22, 22 is in the range of 8% or more and 12% or less of the tire contact width TW.

The groove centerline is defined as an imaginary line connecting the midpoints of the groove width measurement points. When the groove center line of the main groove has a zigzag or wavy shape, the distance to the groove center line is measured using a straight line parallel to the tire circumferential direction that passes through the midpoint of the maximum amplitude on the left and right sides of the groove center line. be done.

The tire contact width TW is the contact surface between the tire and the flat plate when the tire is mounted on the specified rim, the specified internal pressure is applied, the tire is placed perpendicular to the flat plate in the stationary state, and the load corresponding to the specified load is applied. measured as the maximum linear distance in the axial direction of the tire.

The tire contact edge T is the contact surface between the tire and the flat plate when the tire is mounted on the specified rim, the specified internal pressure is applied, the tire is placed perpendicular to the flat plate in the stationary state, and a load corresponding to the specified load is applied. is defined as the position of maximum width in the axial direction of the tire.

A land portion 31 on the outer side in the tire width direction defined by the shoulder main groove 21 is defined as a shoulder land portion. The shoulder land portion 31 is the outermost land portion in the tire width direction and is positioned on the tire ground contact edge T. As shown in FIG. A land portion 32 on the inner side in the tire width direction defined by the shoulder main groove 21 is defined as a second land portion. The second land portion 32 is adjacent to the shoulder land portion 31 with the shoulder main groove 21 interposed therebetween. Further, the land portion 33 located closer to the tire equatorial plane CL than the second land portion 32 is defined as the center land portion. The center land portion 33 may be arranged on the tire equatorial plane CL (see FIG. 2), or may be arranged at a position off the tire equatorial plane CL (not shown).

In addition, in the configuration having four circumferential main grooves 21, 22 as shown in FIG. is defined. Further, for example, in a configuration having five or more circumferential main grooves, two or more rows of center land portions are defined (not shown), and in a configuration having three circumferential main grooves, the second land portion is the center land. (illustration omitted).

2, the maximum contact width Wb1 of the shoulder land portion 31 has a relationship of 0.15≦Wb1/TW≦0.25 with respect to the tire contact width TW. Further, the maximum contact width Wb3 of the center land portion 33 closest to the tire equatorial plane CL preferably has a relationship of 0.15≤Wb3/TW≤0.25 with respect to the tire contact width TW, and 0.18≤. It is more preferable to have a relationship of Wb3/TW≦0.23. In addition, in a configuration including four circumferential main grooves 21 and 22 and five rows of land portions 31 to 33 as shown in FIG. It is preferably in the range of 0.85≤Wb2/Wb1≤0.95 which is slightly narrower than Wb1.

Further, in the configuration of FIG. 2, all of the circumferential main grooves 21, 22 have a zigzag shape or a wavy shape having amplitude in the tire width direction.

Moreover, the shoulder land portion 31 is a rib having a tread surface continuous in the tire circumferential direction, and does not have a lug groove. Also, the second land portion 32 and the center land portion 33 are provided with a plurality of lug grooves 321 and 331, respectively. Moreover, these lug grooves 321 and 331 have an open structure penetrating the land portions 32 and 33 and are arranged at predetermined intervals in the tire circumferential direction. As a result, the second land portion 32 and the center land portion 33 are divided in the tire circumferential direction by the lug grooves 321 and 331 to form block rows.

[Outer edge of shoulder main groove]
3 to 5 are explanatory diagrams showing the groove wall structure of the circumferential main groove shown in FIG. 3 shows an enlarged view of the shoulder main groove 21, and FIGS. 4 and 5 show cross-sectional views of the shoulder main groove 21 in the groove depth direction.

In the configuration of FIG. 2, as shown in FIG. 3, each of the groove opening 211 and the groove bottom 212 of the shoulder main groove 21 has a zigzag or wavy shape with amplitude in the tire width direction.

Here, an outer edge portion and an inner edge portion in the tire width direction are defined at the groove opening and the groove bottom of the main groove, respectively. Further, in each of the outer edge portion and the inner edge portion, an outer maximum amplitude position that is convex outward in the tire width direction and an inner maximum amplitude position that is convex inward in the tire width direction are defined.

The edge portion of the groove opening is defined by an imaginary line connecting the intersections of the groove wall and the tread profile (for example, see FIG. 4) in cross-sectional view in the groove depth direction. In the configuration in which the edge portion has the chamfered portion, the edge portion of the groove opening is connected to the intersection (not shown) of the extension line of the groove wall and the tread profile to draw a virtual line.

The edge portion of the groove bottom is defined by an imaginary line connecting the maximum groove depth positions in a cross-sectional view in the groove depth direction. When the groove bottom of the main groove is a flat straight line at the maximum groove depth (see, for example, FIG. 4), the outer edge and inner edge of the groove bottom are defined by the two end points of the flat straight line. be. On the other hand, when the groove bottom of the main groove has an arc shape or funnel shape (not shown), the maximum groove depth position is one point, and the edge portion of the groove bottom is defined by one point. Therefore, the outer edge and the inner edge of the groove bottom are at the same position. Also, the maximum groove depth position of the main groove is defined by excluding the partial bottom portion formed at the groove bottom of the main groove.

In the configuration of FIG. 3, the groove opening 211 of the shoulder main groove 21 has an amplitude in the tire width direction at each of the outer edge portion 211o on the side of the shoulder land portion 31 and the inner edge portion 211i on the side of the second land portion 32. It has a zigzag shape. Further, the groove bottom portion 212 of the shoulder main groove 21 has a zigzag shape with amplitude in the tire width direction at each of the outer edge portion 212o on the shoulder land portion 31 side and the inner edge portion 212i on the second land portion 32 side. ing.

Further, as shown in FIG. 3, the outer maximum amplitude position P1oo of the outer edge portion 211o of the groove opening portion 211 of the shoulder main groove 21 is greater than the outer maximum amplitude position P2oo of the outer edge portion 212o of the groove bottom portion 212. offset in the direction. That is, on the groove wall of the shoulder main groove 21 on the side of the shoulder land portion 31, the zigzag shape of the outer edge portion 211o of the groove opening portion 211 and the zigzag shape of the outer edge portion 212o of the groove bottom portion 212 project outward in the tire width direction. are arranged with phases shifted from each other at outer maximum amplitude positions P1oo and P2oo.

In the above configuration, (1) the outer maximum amplitude position P2oo of the outer edge portion 212o of the groove bottom portion 212 of the shoulder main groove 21 is the position where the contact width of the shoulder land portion 31 is the smallest (that is, the outer maximum amplitude of the groove opening portion 211). Since the outer maximum amplitude positions P1oo and P2oo of the groove opening portion 211 and the groove bottom portion 212 are located at the same position in the tire circumferential direction (not shown), they are offset in the tire circumferential direction with respect to the amplitude position P1oo). In comparison, the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced. As a result, tearing of the shoulder land portion 31 is suppressed, and tear resistance performance of the tire is improved.

(2) Since the outer maximum amplitude positions P1oo and P2oo of the groove opening 211 and the groove bottom 212 of the shoulder main groove 21 move in the tire circumferential direction toward the groove depth direction, the groove opening 211 and the groove bottom 212 Compared to a configuration (not shown) in which the outer maximum amplitude positions P1oo and P2oo are at the same position in the tire circumferential direction, foreign matter is prevented from entering the shoulder main groove 21, and foreign matter is prevented from entering from the shoulder main groove 21. Excretion is facilitated. As a result, the stone-biting resistance performance of the tire is improved.

Further, the offset amount φoo (see FIG. 3) of the outer maximum amplitude positions P1oo and P2oo at the outer edge portions 211o and 212o of the groove opening portion 211 and the groove bottom portion 212 of the shoulder main groove 21 is 0.03≦φoo/λ1o≦0.45, more preferably 0.10≦φoo/λ1o≦0.25. As a result, the offset amount φoo of the outer maximum amplitude positions P1oo and P2oo is optimized.

The offset amount of the maximum amplitude position is the distance in the tire circumferential direction of the maximum amplitude position in a plan view of the tread, and is measured with the tire mounted on a specified rim, a specified internal pressure applied, and no load applied.

Further, the wavelength λ1o of the outer edge portion 211o of the groove opening portion 211 of the shoulder main groove 21 is set substantially equal to the wavelength λ2o of the outer edge portion 212o of the groove bottom portion 212 . Specifically, the wavelengths λ1o and λ2o of the groove opening 211 and the groove bottom 212 are in the range of 0.90≦λ2o/λ1o≦1.10.

Further, the wavelength λ1o of the groove opening portion 211 of the shoulder main groove 21 is within the range of 0.90≦λ1o/Pa≦1.10 with respect to the pitch length Pa (see FIG. 2) of the lug groove 321 of the second land portion 32. preferably in the range of 0.95≦λ1o/Pa≦1.05. Therefore, the wavelength λ1o of the groove opening 211 is set substantially equal to the pitch length Pa of the lug groove 321 . In addition, in the configuration of FIG. 3 , the total number of pitches of the lug grooves 321 of the second land portion 32 is in the range of 30 or more and 60 or less over the entire circumference of the tire.

Further, the amplitude A1o of the outer edge portion 211o of the groove opening portion 211 of the shoulder main groove 21 has a relationship of 1.00≦A2o/A1o≦2.00 with respect to the amplitude A2o of the outer edge portion 212o of the groove bottom portion 212. It is more preferable to have a relationship of 1.30≦A2o/A1o≦1.80. Therefore, the amplitude A2o of the zigzag shape of the groove bottom 212 is set to be equal to or greater than the amplitude A1o of the zigzag shape of the groove opening 211. FIG. The amplitude A1o of the groove opening 211 of the shoulder main groove 21 has a relationship of 0.10≦A1o/λ1o≦0.25 with respect to the wavelength λ1o of the groove opening 211 of the shoulder land portion 31 .

Further, the maximum inclination angle θ1o of the outer edge portion 211o of the groove opening portion 211 of the shoulder main groove 21 with respect to the tire circumferential direction is θ1o<θ2o with respect to the maximum inclination angle θ2o of the outer edge portion 212o of the groove bottom portion 212 with respect to the tire circumferential direction. have a relationship of That is, the maximum inclination angle θ2o of the groove bottom portion 212 is larger than the maximum inclination angle θ1o of the groove opening portion 211, and the inclination angle of the groove wall of the shoulder main groove 21 increases from the groove opening portion 211 toward the groove bottom portion 212.

The inclination angle of the edge portion is measured as the inclination angle with respect to the tire circumferential direction of an imaginary straight line connecting the maximum amplitude positions of the zigzag or wavy shape of the edge portion in the tread plan view.

Further, it is preferable that the maximum inclination angles θ1o and θ2o of the groove opening 211 and the groove bottom 212 have a relationship of 1.50≦θ2o/θ1o≦2.00. Thereby, the ratio θ2o/θ1o of the maximum inclination angles θ1o and θ2o of the groove opening 211 and the groove bottom 212 is optimized. Further, it is preferable that the difference θ2o−θ1o between the maximum tilt angles θ1o and θ2o is 5 [deg] or more.

Further, in the configuration of FIG. 3, the groove opening 211 of the shoulder main groove 21 has a zigzag shape formed by connecting linear portions of approximately the same length in the tire circumferential direction. Further, the maximum distance L1o in the tire circumferential direction between the outer maximum amplitude position P1oo and the inner maximum amplitude position P1oi at the outer edge portion 211o of the groove opening 211 is 0.50 with respect to the zigzag-shaped wavelength λ1o of the outer edge portion 211o. It preferably has a relationship of ≦L1o/λ1o≦0.60, and preferably has a relationship of 0.50≦L1o/λ1o≦0.55. As a result, the rigidity of the tread surface when the tire is new is made uniform in the tire circumferential direction.

The maximum distance in the tire circumferential direction between the outer maximum amplitude position and the inner maximum amplitude position is the distance in the tire circumferential direction between the adjacent outer maximum amplitude position and the inner maximum amplitude position between these outer maximum amplitude positions. Measured as the larger distance.

On the other hand, the groove bottom portion 212 of the shoulder main groove 21 has a zigzag shape formed by alternately connecting long portions and short portions in the tire circumferential direction. Therefore, the zigzag shape of the groove bottom 212 has a bent shape different from the zigzag shape of the groove opening 211 . Thereby, the offset amount φoo of the outer maximum amplitude positions P1oo and P2oo at the outer edge portions 211o and 212o of the groove opening portion 211 and the groove bottom portion 212 is formed. Further, the maximum distance L2o in the tire circumferential direction between the outer maximum amplitude position P2oo and the inner maximum amplitude position P2oi at the outer edge portion 212o of the groove bottom portion 212 is 0.55≦L2o with respect to the wavelength λ2o of the zigzag shape of the outer edge portion 212o. /λ2o≦0.65, more preferably 0.57≦L2o/λ2o≦0.63.

Further, the maximum distance L1o in the tire circumferential direction between the outer maximum amplitude position P1oo and the inner maximum amplitude position P1oi at the groove opening 211 of the shoulder main groove 21 is the distance between the outer maximum amplitude position P2oo and the inner maximum amplitude position P2oi at the groove bottom 212. The maximum distance L2o in the tire circumferential direction preferably satisfies 1.10≦L2o/L1o≦1.40, and preferably satisfies 1.20≦L2o/L1o≦1.30. Therefore, the maximum distance L2o between the maximum amplitude positions P2oo and P2oi at the groove bottom 212 is set larger than the maximum distance L1o between the maximum amplitude positions P1oo and P1oi at the groove opening 211. FIG. For example, in the configuration of FIG. 3, as described above, the wavelengths λ1o and λ2o of the groove opening 211 and the groove bottom 212 are set to be substantially the same, while the groove bottom 212 of the shoulder main groove 21 has a long portion and a short length. The ratio L2o/L1o is set within the above range by having a zigzag shape formed by alternately connecting the portions in the tire circumferential direction.

Further, as shown in FIG. 3, the offset amount φoo of the outer maximum amplitude positions P1oo and P2oo at the groove opening 211 of the shoulder main groove 21 and the outer edge portions 211o and 212o of the groove bottom 212 is equal to the inner maximum amplitude positions P1oi and P2oi. has a relationship of φoi<φoo with respect to the offset amount φoi of . That is, the zigzag bent portions of the groove opening portion 211 and the groove bottom portion 212 are largely offset at the outer maximum amplitude positions P1oo and P2oo to the outer side in the tire width direction, while the inner maximum amplitude positions P1oi are to the inner side in the tire width direction. , P2oi are aligned. Thereby, the ratio L2o/L1o described above is ensured. The difference φoo-φoi between the offset amounts φoo and φoi is not particularly limited, but is restricted by other conditions such as the ratios L1o/λ1o and L2o/L1o described above. Also, the offset amount φoi may be φoi=0.

4, the groove wall angle α1oo at the outer maximum amplitude position P1oo of the outer edge portion 211o of the groove opening portion 211 of the shoulder main groove 21 corresponds to the groove wall angle α1oo at the outer maximum amplitude position P2oo of the outer edge portion 212o of the groove bottom portion 212. There is a relationship of α2oo<α1oo with respect to the angle α2oo. As described above, due to the offset of the outer maximum amplitude positions P1oo and P2oo between the groove opening 211 and the groove bottom 212, the groove wall angles α1oo and α2oo of the shoulder main groove 21 are three-dimensional in the tire circumferential direction. change to As a result, stone entrapment in the shoulder main groove 21 is effectively suppressed.

Similarly, in FIG. 5, the groove wall angles α1oo and α1oi at the outer maximum amplitude position P1oo and the inner maximum amplitude position P1oi of the outer edge portion 211o of the groove opening 211 of the shoulder main groove 21 have a relationship of α1oo<α1oi. As described above, the zigzag amplitude A2o of the groove bottom 212 is larger than the zigzag amplitude A1o of the groove opening 211, so that the groove wall angles α1oo and α1oi of the shoulder main groove 21 increase in the tire circumferential direction. changes three-dimensionally. As a result, stone entrapment in the shoulder main groove 21 is effectively suppressed.

4, the maximum width Wg2 of the groove bottom portion 212 of the shoulder main groove 21 is 0≦Wg2/Wg1≦0.60 with respect to the maximum width Wg1 of the groove opening portion 211 (that is, the groove width of the shoulder main groove 21). and more preferably 0.35≤Wg2/Wg1≤0.45.

[Inner edge of shoulder main groove]
FIG. 6 is an explanatory diagram showing the inner edge portion of the shoulder main groove 21 shown in FIG. This figure shows an enlarged view of the maximum amplitude position of the shoulder main groove 21 inward in the tire width direction of the zigzag shape.

In the configuration of FIG. 3, as described above, the outer maximum amplitude position P1oo of the outer edge portion 211o of the groove opening portion 211 coincides with the groove bottom portion 212 on the groove wall on the outer side in the tire width direction of the shoulder main groove 21 having a zigzag shape. is offset in the tire circumferential direction with respect to the outer maximum amplitude position P2oo of the outer edge portion 212o. Further, the inner maximum amplitude positions P1oi and P2oi of the groove opening 211 and the groove bottom 212 are aligned in the tire circumferential direction. Since the groove wall on the tire width direction outer side of the shoulder main groove 21 has the above-described configuration, tearing of the shoulder land portion 31 is suppressed, and stone trapping of the shoulder main groove 21 is suppressed.

Further, in the configuration of FIG. 3, as shown in FIG. is aligned in the tire circumferential direction with respect to the inner maximum amplitude position P2ii of the inner edge portion 212i. In this manner, at the inward bending position in the tire width direction of the shoulder main groove 21, the maximum amplitude positions P1ii and P2ii of the groove opening 211 and the groove bottom 212 are aligned in the tire circumferential direction. Also, the offset amount φii of the inner maximum amplitude positions P1ii and P2ii of the groove opening 211 and the groove bottom 212 may be φii=0.

Moreover, in the structure of FIG. 2, the second land part 32 is provided with the lug groove 321 as mentioned above. The lug grooves 321 are thin shallow grooves that penetrate the second land portion 32 in the tire width direction and open into the shoulder main grooves 21 . Further, the groove width W21 (see FIG. 3) of the lug grooves 321 preferably has a relationship of 0.02≦W21/Pa≦0.10 with respect to the pitch length Pa (see FIG. 2) of the lug grooves 321. It is more preferable to have a relationship of 0.04≦W21/Pa≦0.06. Further, it is preferable that the groove depth H21 (see FIG. 5) of the lug groove 321 and the groove depth Hg1 of the shoulder main groove 21 have a relationship of 0.10≦H21/Hg1≦0.50. It is more preferable to have a relationship of 15≦H21/Hg1≦0.28.

Further, as shown in FIG. 2 , the opening of the lug groove 321 with respect to the shoulder main groove 21 is offset in the tire circumferential direction with respect to the zigzag bent portions of the main grooves 21 and 22 . Further, the maximum distance Lp (see FIG. 6) in the tire circumferential direction between the opening of the lug groove 321 and the inner maximum amplitude position P1ii of the groove opening 211 of the shoulder main groove 21 is equal to the pitch length Pa of the lug groove 321 (see FIG. 2). ), it is preferably in the range of 0.03 ≤ Lp/Pa ≤ 0.15, more preferably in the range of 0.04 ≤ Lp/Pa ≤ 0.08.

[Groove wall structure of center main groove]
FIG. 7 is an explanatory diagram showing the groove wall structure of the circumferential main groove shown in FIG. The figure shows an enlarged view of the center main groove 22 .

2, the groove wall structure of the shoulder main groove 21 is slightly different from the groove wall structure of the center main groove 22, as shown by a comparison of FIGS. However, without being limited to this, the groove wall structure of the shoulder main groove 21 may have the same structure as the groove wall structure of the center main groove 22 . Here, the groove wall structure of the center main groove 22 will be described with a focus on differences from the groove wall structure of the shoulder main groove 21, and the description of the common points will be omitted.

In the configuration of FIG. 7, the groove opening 221 of the center main groove 22 has an amplitude in the tire width direction at each of the outer edge portion 221o on the second land portion 32 side and the inner edge portion 221i on the center land portion 33 side. It has a zigzag shape. Further, the groove bottom portion 222 of the center main groove 22 has a zigzag shape with amplitude in the tire width direction at each of the outer edge portion 222o on the second land portion 32 side and the inner edge portion 222i on the center land portion 33 side. ing.

7, the groove opening 221 of the center main groove 22 and the edge portions 221o, 221i, 222o, and 222i of the groove bottom 222 alternately connect the long portions and the short portions in the tire circumferential direction. It has a zigzag shape. Further, the long portions of the edge portions 221o and 221i of the groove opening portion 221 have an arc shape that protrudes inward in the tire width direction (see the phantom lines in the drawing), and the short portions have a linear shape. . Both the long and short portions of the edge portions 222o and 222i of the groove bottom portion 222 have linear shapes.

Further, the outer maximum amplitude position P1oo of the outer edge portion 221o of the groove opening portion 221 of the center main groove 22 is offset in the tire circumferential direction from the outer maximum amplitude position P2oo of the outer edge portion 222o of the groove bottom portion 222. be. That is, in the groove wall of the center main groove 22 on the side of the second land portion 32, the zigzag shape of the outer edge portion 221o of the groove opening portion 221 and the zigzag shape of the outer edge portion 222o of the groove bottom portion 222 project outward in the tire width direction. are arranged with phases shifted from each other at outer maximum amplitude positions P1oo and P2oo.

Further, the offset amount φoo (see FIG. 7) of the outer maximum amplitude positions P1oo and P2oo at the outer edge portions 221o and 222o of the groove opening portion 221 and the groove bottom portion 222 of the center main groove 22 is the outer edge portion 221o of the groove opening portion 221. satisfies the condition of the ratio φoo/λ1o in the shoulder main groove 21 with respect to the wavelength λ1o of . The offset amount φoo of the shoulder main groove 21 in FIG. 3 is set larger than the offset amount φoo of the center main groove 22 in FIG. As a result, the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced, and tear generation in the shoulder land portion 31 is effectively enhanced.

In addition, the wavelength λ1o of the outer edge portion 221o of the groove opening portion 221 of the center main groove 22 is set to be substantially the same as the wavelength λ2o of the outer edge portion 222o of the groove bottom portion 222 . Specifically, the wavelengths λ1o and λ2o of the groove opening 221 and the groove bottom 222 satisfy the condition of the ratio λ2o/λ1o in the shoulder main groove 21 described above.

Further, the amplitude A1o of the outer edge portion 221o of the groove opening portion 221 of the center main groove 22 satisfies the condition of the ratio A2o/A1o of the shoulder main groove 21 to the amplitude A2o of the outer edge portion 222o of the groove bottom portion 222 described above. . The amplitude A1o of the shoulder main groove 21 in FIG. 3 is set smaller than the amplitude A1o of the center main groove 22 in FIG. It is set larger than A1o. As a result, the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced, and tear generation in the shoulder land portion 31 is effectively enhanced.

Further, the maximum inclination angle θ1o of the outer edge portion 221o of the groove opening 221 of the center main groove 22 with respect to the tire circumferential direction is substantially the same as the maximum inclination angle θ2o of the outer edge portion 222o of the groove bottom portion 222 with respect to the tire circumferential direction. is set. Specifically, the maximum inclination angles θ1o and θ2o of the groove opening 221 and the groove bottom 222 have a relationship of 1.00≦θ2o/θ1o≦1.10. Therefore, the ratio .theta.2o/.theta.1o of the shoulder main groove 21 in FIG. 3 is set larger than the ratio .theta.2o/.theta.1o of the center main groove 22 in FIG. As a result, the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced, and tear generation in the shoulder land portion 31 is effectively enhanced.

Further, the maximum distance L1o in the tire circumferential direction between the outer maximum amplitude position P1oo and the inner maximum amplitude position P1oi at the outer edge portion 221o of the groove opening 221 of the center main groove 22 is the wavelength λ1o of the zigzag shape of the outer edge portion 221o. On the other hand, the above condition of the ratio L1o/λ1o in the shoulder main groove 21 is satisfied. However, in the configuration of FIG. 7, as described above, the edge portions 221o and 221i of the groove opening portion 221 of the center main groove 22 have a zigzag shape formed by alternately connecting long portions and short portions in the tire circumferential direction. have. Therefore, the ratio L1o/λ1o of the center main groove 22 in FIG. 7 is set larger than the ratio L1o/λ1o of the shoulder main groove 21 in FIG. As a result, the ability to remove foreign matter that has entered the center main groove 22 is improved.

In addition, the maximum distance L2o in the tire circumferential direction between the outer maximum amplitude position P2oo and the inner maximum amplitude position P2oi at the outer edge portion 222o of the groove bottom portion 222 of the center main groove 22 is different from the wavelength λ2o of the zigzag shape of the outer edge portion 222o. to satisfy the condition of the ratio L2o/λ2o in the shoulder main groove 21 described above. 7, the edge portions 222o and 222i of the groove bottom portion 222 of the center main groove 22 have a zigzag shape formed by alternately connecting long portions and short portions in the tire circumferential direction. have.

In addition, in the configuration of FIG. 7, as a difference from the groove wall structure of the shoulder main groove 21 in FIG. The maximum circumferential distance L1o is substantially the same as the maximum tire circumferential distance L2o between the outer maximum amplitude position P2oo and the inner maximum amplitude position P2oi at the groove bottom 222, and the ratio L2o/L1o is 1.00≦L2o/. It has a relationship of L1o≦1.10. Further, as described above, the wavelength λ1o of the outer edge portion 221o of the groove opening portion 221 of the center main groove 22 is set to be substantially the same as the wavelength λ2o of the outer edge portion 222o of the groove bottom portion 222. The offset amount φoo of the outer maximum amplitude positions P1oo and P2oo of the groove 22 is substantially the same as the offset amount φoi of the inner maximum amplitude positions P1oi and P2oi. As a result, the ability to remove foreign matter that has entered the center main groove 22 is improved.

[Groove center line of shoulder main groove]
FIG. 8 is an explanatory diagram showing the shoulder main groove 21 shown in FIG. 3, and particularly shows the relationship between the centerline of the groove opening 211 and the centerline of the groove bottom 212 of the shoulder main groove 21. FIG.

As described above with reference to FIG. 3, in the groove wall structure on the outer side in the tire width direction of the shoulder main groove 21 (that is, on the side of the shoulder land portion 31), the zigzag shape of the outer edge portion 211o of the groove opening portion 211 and the outer side of the groove bottom portion 212 The zigzag shape of the edge portion 212o is offset in the tire circumferential direction at maximum amplitude positions P1oo and P2oo to the outside in the tire width direction.

In the configuration of FIG. 3, the groove opening 211 and the groove bottom 212 of the shoulder main groove 21 have a constant width, and the outer edges 211o and 212o and the inner edges 211i and 212i of the groove opening 211 and the groove bottom 212 are Almost parallel. Therefore, the feature of the groove wall structure on the outer side in the tire width direction of the shoulder main groove 21 described above is the relationship between the center line 211c of the groove opening 211 and the center line 212c of the groove bottom 212 of the shoulder main groove 21 shown in FIG. The same holds true for

Specifically, in FIG. 8, the outer maximum amplitude positions P1co and P2co that are convex outward in the tire width direction and the inner side in the tire width direction are located at the center lines 211c and 212c of the groove opening 211 and the groove bottom 212 of the shoulder main groove 21. Define the inner maximum amplitude positions P1ci and P2ci that are convex to .

At this time, the outer maximum amplitude position P1co of the center line 211c of the groove opening 211 is offset from the outer maximum amplitude position P2co of the center line 212c of the groove bottom 212 in the tire circumferential direction. As a result, the tear resistance performance of the tire is improved, and the stone bite resistance performance of the tire is improved.

Further, the offset amount φco (see FIG. 8) of the outer maximum amplitude positions P1co and P2co at the centerlines 211c and 212c of the groove opening 211 and the groove bottom 212 of the shoulder main groove 21 is the wavelength of the centerline 211c of the groove opening 211. 0.03≦φco/λ1c≦0.45, and more preferably 0.10≦φco/λ1c≦0.25 with respect to λ1c. As a result, the offset amount φco of the outer maximum amplitude positions P1co and P2co is optimized.

Further, the wavelength λ1c of the centerline 211c of the groove opening 211 of the shoulder main groove 21 is set to be substantially the same as the wavelength λ2c of the centerline 212c of the groove bottom 212 . Specifically, the wavelengths λ1c and λ2c of the groove opening 211 and the groove bottom 212 are in the range of 0.90≦λ2c/λ1c≦1.10.

Further, the wavelength λ1c of the groove opening 211 of the shoulder main groove 21 is within the range of 0.90≦λ1c/Pa≦1.10 with respect to the pitch length Pa (see FIG. 2) of the lug groove 321 of the second land portion 32. preferably in the range of 0.95≦λ1c/Pa≦1.05. Therefore, the wavelength λ1c of the groove opening 211 is set substantially equal to the pitch length Pa of the lug groove 321 .

Further, the amplitude A1c of the center line 211c of the groove opening 211 of the shoulder main groove 21 and the amplitude A2c of the center line 212c of the groove bottom 212 have a relationship of 1.00≦A2c/A1c≦2.00. It is preferable to have a relationship of 1.30≦A2c/A1c≦1.80. Therefore, the zigzag amplitude A2c of the groove bottom 212 is set to be greater than or equal to the zigzag amplitude A1c of the groove opening 211 .

Further, the maximum inclination angle θ1c of the center line 211c of the groove opening 211 of the shoulder main groove 21 with respect to the tire circumferential direction and the maximum inclination angle θ2c of the center line 212c of the groove bottom 212 with respect to the tire circumferential direction have a relationship of θ1c<θ2c. have That is, the maximum inclination angle θ2c of the groove bottom 212 is larger than the maximum inclination angle θ1c of the groove opening 211 , and the inclination angle of the groove wall of the shoulder main groove 21 increases from the groove opening 211 toward the groove bottom 212 .

Further, it is preferable that the maximum inclination angles θ1c and θ2c of the groove opening 211 and the groove bottom 212 have a relationship of 1.50≦θ2c/θ1c≦2.00. As a result, the ratio θ2c/θ1c between the maximum inclination angles θ1c and θ2c of the groove opening 211 and the groove bottom 212 is optimized. It is preferable that the difference θ2c−θ1c between the maximum tilt angles θ1c and θ2c is 5 [deg] or more.

8, the center line 211c of the groove opening 211 of the shoulder main groove 21 has a zigzag shape formed by connecting linear portions of approximately the same length in the tire circumferential direction. Further, the maximum distance L1c in the tire circumferential direction between the outer maximum amplitude position P1co and the inner maximum amplitude position P1ci at the center line 211c of the groove opening 211 is 0.50≦L1c with respect to the zigzag-shaped wavelength λ1c of the center line 211c. /λ1c≦0.60, preferably 0.50≦L1c/λ1c≦0.55. As a result, the rigidity of the tread surface when the tire is new is made uniform in the tire circumferential direction.

On the other hand, the center line 212c of the groove bottom portion 212 of the shoulder main groove 21 has a zigzag shape formed by alternately connecting long portions and short portions in the tire circumferential direction. Therefore, the zigzag shape of the groove bottom 212 has a bent shape different from the zigzag shape of the groove opening 211 . As a result, the offset amounts φco of the outer maximum amplitude positions P1co and P2co at the center lines 211c and 212c of the groove opening 211 and the groove bottom 212 are formed. Further, the maximum distance L2c in the tire circumferential direction between the outer maximum amplitude position P2co and the inner maximum amplitude position P2ci at the center line 212c of the groove bottom 212 is 0.55≦L2c/λ2c with respect to the wavelength λ2c of the zigzag shape of the center line 212c. It is preferable to have a relationship of ≦0.65, and more preferably to have a relationship of 0.57≦L2c/λ2c≦0.63.

Further, the maximum distance L1c in the tire circumferential direction between the outer maximum amplitude position P1co and the inner maximum amplitude position P1ci at the groove opening 211 of the shoulder main groove 21 is the same as the outer maximum amplitude position P2co and the inner maximum amplitude position P2ci at the groove bottom 212. 1.10≤L2c/L1c≤1.40, and preferably 1.20≤L2c/L1c≤1.30 with respect to the maximum distance L2c in the tire circumferential direction. Therefore, the maximum distance L2c between the maximum amplitude positions P2co and P2ci at the groove bottom 212 is set larger than the maximum distance L1c between the maximum amplitude positions P1co and P1ci at the groove opening 211. FIG. For example, in the configuration of FIG. 8, as described above, the wavelengths λ1c and λ2c of the groove opening 211 and the groove bottom 212 are set to be substantially the same, and the groove bottom 212 of the shoulder main groove 21 is different from the long portion and the short portion. The ratio L2c/L1c is set within the above range by having a zigzag shape formed by alternately connecting the portions in the tire circumferential direction.

Further, as shown in FIG. 8, the offset amount φco of the outer maximum amplitude positions P1co and P2co from the center lines 211c and 212c of the groove opening portion 211 and the groove bottom portion 212 of the shoulder main groove 21 is different from that of the inner maximum amplitude positions P1ci and P2ci. There is a relationship of φci<φco with respect to the offset amount φci. That is, the zigzag bent portions of the groove opening portion 211 and the groove bottom portion 212 are largely offset at the outer maximum amplitude positions P1co and P2co to the outer side in the tire width direction, while the inner maximum amplitude position P1ci to the inner side in the tire width direction. , P2ci are aligned. Thereby, the ratio L2c/L1c described above is ensured. The difference φco−φci between the offset amounts φco and φci is not particularly limited, but is restricted by other conditions such as the ratios L1c/λ1c and L2c/L1c described above. Also, the offset amount φci may be φci=0.

[Groove center line of center main groove]
FIG. 9 is an explanatory diagram showing the center main groove 22 shown in FIG. 7. This figure shows the relationship between the center line of the groove opening 221 of the center main groove 22 and the center line of the groove bottom 222, with the reference numerals and dimension symbols changed from those of FIG.

2, the groove wall structure of the shoulder main groove 21 is slightly different from the groove wall structure of the center main groove 22, as shown by a comparison of FIGS. However, without being limited to this, the groove wall structure of the shoulder main groove 21 may have the same structure as the groove wall structure of the center main groove 22 . Here, the groove wall structure of the center main groove 22 will be described with a focus on differences from the groove wall structure of the shoulder main groove 21, and the description of the common points will be omitted.

As described above with reference to FIG. 7, in the groove wall structure on the outer side of the center main groove 22 in the tire width direction (that is, on the side of the second land portion 32), the zigzag shape of the outer edge portion 221o of the groove opening portion 221 and the outer side of the groove bottom portion 222 The zigzag shape of the edge portion 222o is offset in the tire circumferential direction at maximum amplitude positions P1oo and P2oo to the outside in the tire width direction.

In the configuration of FIG. 9, the groove opening 221 and the groove bottom 222 of the center main groove 22 have a constant width, and the outer edges 221o and 222o and the inner edges 221i and 222i of the groove opening 221 and the groove bottom 222 are Almost parallel. Therefore, the feature of the groove wall structure on the outside in the tire width direction of the shoulder main groove 21 described above is the relationship between the center line 221c of the groove opening 221 of the center main groove 22 and the center line 222c of the groove bottom 222 shown in FIG. The same holds true for

Specifically, in FIG. 9, the outer maximum amplitude positions P1co and P2co that are convex outward in the tire width direction and the inner side in the tire width direction are located at the center lines 221c and 222c of the groove opening portion 221 and the groove bottom portion 222 of the center main groove 22. Define the inner maximum amplitude positions P1ci and P2ci that are convex to .

At this time, the outer maximum amplitude position P1co of the center line 221c of the groove opening 221 is offset from the outer maximum amplitude position P2co of the center line 222c of the groove bottom 222 in the tire circumferential direction. As a result, the tear resistance performance of the tire is improved, and the stone bite resistance performance of the tire is improved.

Further, the offset amount φco (see FIG. 9) of the outer maximum amplitude positions P1co and P2co at the center lines 221c and 222c of the groove opening 221 and the groove bottom 222 of the center main groove 22 is the wavelength of the center line 221c of the groove opening 221. The condition of the ratio φco/λ1c in the shoulder main groove 21 to λ1c is satisfied. The offset amount φco of the shoulder main groove 21 in FIG. 8 is set larger than the offset amount φco of the center main groove 22 in FIG. 9 . As a result, the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced, and tear generation in the shoulder land portion 31 is effectively enhanced.

Also, the wavelength λ1c of the center line 221c of the groove opening 221 of the center main groove 22 is set to be substantially the same as the wavelength λ2c of the center line 222c of the groove bottom 222 . Specifically, the wavelengths λ1c and λ2c of the groove opening 221 and the groove bottom 222 satisfy the condition of the ratio λ2c/λ1c in the shoulder main groove 21 described above.

Further, the wavelength λ1c of the groove opening portion 221 of the center main groove 22 satisfies the condition of the ratio λ1c/Pa of the shoulder main groove 21 to the pitch length Pa (see FIG. 2) of the lug groove 321 of the second land portion 32. Fulfill.

Further, the amplitude A1c of the center line 221c of the groove opening 221 of the center main groove 22 satisfies the condition of the ratio A2c/A1c in the shoulder main groove 21 to the amplitude A2c of the center line 222c of the groove bottom 222. The amplitude A1c of the shoulder main groove 21 in FIG. 8 is set smaller than the amplitude A1c of the center main groove 22 in FIG. It is set larger than A1c. As a result, the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced, and tear generation in the shoulder land portion 31 is effectively enhanced.

Further, the maximum inclination angle θ1c of the center line 221c of the groove opening 221 of the center main groove 22 with respect to the tire circumferential direction is set substantially equal to the maximum inclination angle θ2c of the center line 222c of the groove bottom 222 with respect to the tire circumferential direction. ing. Specifically, the maximum inclination angles θ1c and θ2c of the groove opening 221 and the groove bottom 222 have a relationship of 1.00 [deg]≦θ2c/θ1c≦1.10 [deg]. Therefore, the ratio .theta.2c/.theta.1c of the shoulder main groove 21 in FIG. 8 is set larger than the ratio .theta.2c/.theta.1c of the center main groove 22 in FIG. As a result, the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced, and tear generation in the shoulder land portion 31 is effectively enhanced.

Further, the maximum distance L1c in the tire circumferential direction between the outer maximum amplitude position P1co and the inner maximum amplitude position P1ci on the center line 221c of the groove opening 221 of the center main groove 22 is The condition of the ratio L1c/λ1c in the shoulder main groove 21 described above is satisfied. However, in the configuration of FIG. 9, as described above, the center line 221c of the groove opening 221 of the center main groove 22 has a zigzag shape formed by alternately connecting long portions and short portions in the tire circumferential direction. doing. Therefore, the ratio L1c/λ1c of the center main groove 22 in FIG. 9 is set larger than the ratio L1c/λ1c of the shoulder main groove 21 in FIG. As a result, the ability to remove foreign matter that has entered the center main groove 22 is improved.

Further, the maximum distance L2c in the tire circumferential direction between the outer maximum amplitude position P2co and the inner maximum amplitude position P2ci on the centerline 222c of the groove bottom 222 of the center main groove 22 is the wavelength λ2c of the zigzag shape of the centerline 222c. The condition of the ratio L2c/λ2c in the shoulder main groove 21 is satisfied. 9, the center line 222c of the groove bottom 222 of the center main groove 22 has a zigzag shape formed by alternately connecting the long and short portions in the tire circumferential direction. doing.

In addition, in the configuration of FIG. 9, as a difference from the groove wall structure of the shoulder main groove 21 in FIG. The maximum circumferential distance L1c is substantially the same as the maximum tire circumferential distance L2c between the outer maximum amplitude position P2co and the inner maximum amplitude position P2ci at the groove bottom 222, and the ratio L2c/L1c is 1.00≦L2c/. It has a relationship of L1c≦1.10. Further, as described above, the wavelength λ1c of the groove opening 221 of the center main groove 22 is set to be substantially the same as the wavelength λ2c of the groove bottom 222, so that the outer maximum amplitude positions P1co and P2co of the center main groove 22 is substantially the same as the offset amount φci of the inner maximum amplitude positions P1ci and P2ci. As a result, the ability to remove foreign matter that has entered the center main groove 22 is improved.

[effect]
As described above, the pneumatic tire 1 includes the circumferential main groove 21 extending in the tire circumferential direction and the land portions 31 and 32 defined by the circumferential main groove 21 (see FIG. 2). In addition, each of the groove opening 211 and the groove bottom 212 of the circumferential main groove 21 has a zigzag shape or a wavy shape with amplitude in the tire width direction (see FIG. 3). Further, the outer maximum amplitude position P1oo of the outer edge portion 211o of the groove opening portion 211 is offset from the corresponding outer maximum amplitude position P2oo of the outer edge portion 212o of the groove bottom portion 212 in the tire circumferential direction.

In the above configuration, (1) the outer maximum amplitude position P2oo of the outer edge portion 212o of the groove bottom portion 212 of the shoulder main groove 21 is the position where the contact width of the shoulder land portion 31 is the smallest (that is, the groove opening of the shoulder main groove 21). Since the outer maximum amplitude position P1oo) of the portion 211 is offset in the tire circumferential direction, the outer maximum amplitude positions P1oo and P2oo of the groove opening 211 and the groove bottom 212 are at the same position in the tire circumferential direction. (not shown), the rigidity of the groove wall of the shoulder land portion 31 is three-dimensionally reinforced. As a result, there is an advantage that the tearing of the shoulder land portion 31 is suppressed and the tear resistance performance of the tire is improved.

(2) Since the outer maximum amplitude positions P1oo and P2oo of the groove opening 211 and the groove bottom 212 of the shoulder main groove 21 move in the tire circumferential direction toward the groove depth direction, the groove opening 211 and the groove bottom 212 Compared to a configuration (not shown) in which the outer maximum amplitude positions P1oo and P2oo are at the same position in the tire circumferential direction, foreign matter is prevented from entering the shoulder main groove 21, and foreign matter is prevented from entering from the shoulder main groove 21. Excretion is facilitated. As a result, there is an advantage that the stone bite resistance performance of the tire is improved.

In the pneumatic tire 1, the offset amount φoo (see FIG. 3) of the outer maximum amplitude positions P1oo and P2oo at the outer edge portions 211o and 212o of the groove opening portion 211 and the groove bottom portion 212 is the outer edge portion of the groove opening portion 211. It has a relationship of 0.03≦φoo/λ1o≦0.45 with respect to the wavelength λ1o of the portion 211o (see FIG. 3). This has the advantage of optimizing the offset amount φoo of the outer maximum amplitude positions P1oo and P2oo. That is, the above lower limit ensures the effect of improving tire tear resistance and stone bite resistance due to the offset of the outer maximum amplitude positions P1oo and P2oo. Further, the above upper limit secures the amplitude A2o of the groove bottom portion 212, thereby securing the effect of improving stone-biting resistance performance.

Further, in the pneumatic tire 1, the maximum inclination angle θ1o of the outer edge portion 211o of the groove opening 211 with respect to the tire circumferential direction is θ1o with respect to the maximum inclination angle θ2o of the outer edge portion 212o of the groove bottom portion 212 with respect to the tire circumferential direction. <θ2o (see FIG. 3). In such a configuration, the inclination angle of the groove wall of the shoulder main groove 21 with respect to the tire circumferential direction increases from the groove opening 211 toward the groove bottom 212, so compared to a configuration (not shown) in which the wall inclination angle is constant. Therefore, there is an advantage that the tear resistance performance and the stone bite resistance performance of the tire are improved.

Further, in the pneumatic tire 1, the maximum inclination angles θ1o and θ2o of the groove opening portion 211 and the groove bottom portion 212 have a relationship of 1.50≦θ2o/θ1o≦2.00. This has the advantage of optimizing the ratio θ2o/θ1o of the maximum tilt angles θ1o and θ2o. That is, the above lower limit ensures the effect of improving the tear resistance performance and the stone bite resistance performance of the tire due to changes in the inclination angle of the groove wall. In addition, the above upper limit suppresses unipolar concentration of the load caused by an excessive change in the inclination angle of the groove wall.

Further, in the pneumatic tire 1, the wavelength λ1o of the outer edge portion 211o of the groove opening portion 211 has a relationship of 0.90≦λ2o/λ1o≦1.10 with respect to the wavelength λ2o of the outer edge portion 212o of the groove bottom portion 212. (see FIG. 3). Thereby, the wavelength λ2o of the groove bottom 212 is set to be substantially the same as the wavelength λ1o of the groove opening 211 .

In the pneumatic tire 1, the amplitude A1o of the outer edge portion 211o of the groove opening portion 211 has a relationship of 1.00≦A2o/A1o≦2.00 with respect to the amplitude A2o of the outer edge portion 212o of the groove bottom portion 212. (see FIG. 3). In this configuration, the amplitude A2o of the zigzag shape of the groove bottom 212 is set to be equal to or greater than the amplitude A1o of the zigzag shape of the groove opening 211, so that the three-dimensional groove wall structure of the shoulder main groove 21 can be efficiently formed. There are advantages.

In the pneumatic tire 1, the maximum distance L1o in the tire circumferential direction between the outer maximum amplitude position P1oo and the inner maximum amplitude position P2oi at the outer edge portion 211o of the groove opening 211 is The maximum distance L2o in the tire circumferential direction between the outer maximum amplitude position P2oo and the inner maximum amplitude position P2oi has a relationship of 1.10≦L2o/L1o≦1.40 (see FIG. 3). As a result, there is an advantage that the three-dimensional groove wall structure of the shoulder main groove 21 can be efficiently formed.

In the pneumatic tire 1, the offset amount φoo of the outer maximum amplitude positions P1oo and P2oo at the outer edge portions 211o and 212o of the groove opening portion 211 and the groove bottom portion 212 is equal to the offset amount φoi of the inner maximum amplitude positions P1oi and P2oi. φoi<φoo (see FIG. 3). As a result, there is an advantage that the offset amount φoo of the outer maximum amplitude positions P1oo and P2oo can be efficiently formed.

In the pneumatic tire 1, the maximum distance L2o in the tire circumferential direction between the outer maximum amplitude position P2oo and the inner maximum amplitude position P2oi at the outer edge portion 212o of the groove bottom portion 212 is It has a relationship of 0.55≦L2o/λ2o≦0.65 (see FIG. 3). As a result, there is an advantage that the offset amount φoo of the outer maximum amplitude positions P1oo and P2oo can be efficiently formed.

In the pneumatic tire 1, the maximum distance L1o in the tire circumferential direction between the outer maximum amplitude position P1oo and the inner maximum amplitude position P1oi at the outer edge portion 211o of the groove opening 211 is 0.50≦L1o/λ1o≦0.60 (see FIG. 3). As a result, there is an advantage that the rigidity of the tread surface of a new tire is made uniform in the tire circumferential direction.

In this pneumatic tire 1, the groove wall angle α1oo at the outer maximum amplitude position P1oo of the outer edge portion 211o of the groove opening portion 211 is the groove wall angle α2oo at the outer maximum amplitude position P2oo of the outer edge portion 212o of the groove bottom portion 212. has a relationship of α2oo<α1oo (see FIG. 4). In this configuration, due to the offset of the outer maximum amplitude positions P1oo and P2oo between the groove opening portion 211 and the groove bottom portion 212, the groove wall angles α1oo and α2oo of the shoulder main groove 21 become three-dimensional in the tire circumferential direction. change to As a result, there is an advantage that stone entrapment in the shoulder main groove 21 is effectively suppressed.

In the pneumatic tire 1, the groove wall angles α1oo and α1oi at the outer maximum amplitude position P1oo and the inner maximum amplitude position P1oi of the outer edge portion 211o of the groove opening 211 have a relationship of α1oo<α1oi (see FIG. 5). ). As a result, the groove wall angles α1oo and α1oi of the shoulder main groove 21 change three-dimensionally in the tire circumferential direction, so there is the advantage that stone entrapment in the shoulder main groove 21 is effectively suppressed.

In addition, in the pneumatic tire 1, the circumferential main groove that satisfies the above conditions is the shoulder main groove 21 located on the outermost side in the tire width direction (see FIG. 2). Since tearing of the land portion is likely to occur in the shoulder land portion 31, the shoulder main groove 21 that defines the shoulder land portion 31 satisfies the above conditions, thereby effectively improving tear resistance performance of the tire.

Further, in the pneumatic tire 1, the land portion 31 on the outer side in the tire width direction defined by the circumferential main groove 21 is a rib continuous in the tire circumferential direction, and the tire is defined by the circumferential main groove 21. The land portion 32 on the inner side in the width direction has a plurality of lug grooves 321 (see FIG. 2).

The pneumatic tire 1 also includes a circumferential main groove 21 extending in the tire circumferential direction, and land portions 31 and 32 defined by the circumferential main groove 21 (see FIG. 2). In addition, each of the groove opening 211 and the groove bottom 212 of the circumferential main groove 21 has a zigzag shape or a wavy shape with amplitude in the tire width direction (see FIG. 8). Further, the outer maximum amplitude position P1co of the center line 211c of the groove opening 211 is offset from the corresponding outer maximum amplitude position P2co of the center line 212c of the groove bottom 212 in the tire circumferential direction. As a result, there is an advantage that the tear resistance performance of the tire is improved and the stone bite resistance performance of the tire is improved.

FIG. 10 is a chart showing results of performance tests of the pneumatic tire according to the embodiment of the invention.

In this performance test, multiple types of test tires were evaluated for (1) tear resistance and (2) stone bite resistance. Also, a test tire having a tire size of 315/80R22.5 is mounted on a JATMA specified rim, and the JATMA specified internal pressure and load are applied to the test tire. Also, the test tire is mounted on the drive shaft of the test vehicle 2-DD (front loader).

(1) In the evaluation of the tear resistance performance, after the test vehicle ran over a curb with a height of 200 [mm] 20 times while running, tearing was observed in the shoulder land portion. Then, based on this observation result, index evaluation is performed with the conventional example as the standard (100). This numerical value is preferably as large as possible.

(2) In the evaluation of resistance to stone entrapment, the number of foreign objects caught in the main groove after the test vehicle traveled 20,000 [km] on a general paved road was counted. Then, based on this result, index evaluation is performed with the conventional example as the standard (100). This numerical value is preferably as large as possible.

The test tires of Examples 1 to 11 had the configurations shown in FIGS. 1 and 2, and the zigzag shape of the groove openings and the zigzag shape of the groove bottoms of the circumferential main grooves 21 and 22 were offset in the tire circumferential direction. be done. Further, all of the circumferential main grooves 21 and 22 have the structure shown in FIG. They are offset in the tire circumferential direction, and the maximum amplitude positions P1ii and P2ii on the inner side in the tire width direction are aligned. Further, the tire contact width TW is 275 [mm], and the distances Dg1 and Dg2 between the circumferential main grooves 21 and 22 are Dg1=80 [mm] and Dg2=29 [mm]. The zigzag-shaped wavelength λ1o of the groove openings 211 and 221 of the circumferential main grooves 21 and 22 is λ1o=77 [mm], and the amplitude A1o is 13 [mm].

In the test tire of the conventional example, in the test tire of Example 1, the zigzag shape of the groove opening and the zigzag shape of the groove bottom in all the circumferential main grooves 21 and 22 are the maximum amplitudes on both the outer side and the inner side in the tire width direction. Positions are aligned in the tire circumferential direction.

As can be seen from the test results, the test tires of the examples are improved in tear resistance and stone entrapment resistance.

1 pneumatic tire; 11 bead core; 12 bead filler; 13 carcass layer; 14 belt layer; 212 groove bottom; 22 center main groove; 31 shoulder land; 32 second land; 321 lug groove; 33 center land

Claims (18)

A pneumatic tire comprising a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove,
Each of the groove opening and the groove bottom of the circumferential main groove has a zigzag shape or a wavy shape with amplitude in the tire width direction,
An outer edge portion located on the outer side in the tire width direction is defined at each of the groove opening portion and the groove bottom portion, and the outer maximum amplitude position and the inner convex portion are convex to the outer side in the tire width direction at the outer edge portion. define the inner maximum amplitude position,
The outer maximum amplitude position of the outer edge portion of the groove opening is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the outer edge portion of the corresponding groove bottom , and
The maximum distance L2o in the tire circumferential direction between the outer maximum amplitude position and the inner maximum amplitude position at the outer edge of the groove bottom is 0.55≦L2o with respect to the wavelength λ2o of the outer edge of the groove bottom. /λ2o≦0.65 . The offset amount φoo of the outer maximum amplitude position at the outer edge portion of the groove opening and the groove bottom is 0.03≤φoo/λ1o≤0.03 with respect to the wavelength λ1o of the outer edge portion of the groove opening. 2. The pneumatic tire of claim 1 having 45 relationships. 2. A maximum inclination angle .theta.1o of the outer edge portion of the groove opening with respect to the tire circumferential direction and a maximum inclination angle .theta.2o of the outer edge portion of the groove bottom with respect to the tire circumferential direction have a relationship of .theta.1o<.theta.2o. Or the pneumatic tire according to 2. 4. The pneumatic tire according to claim 3, wherein the maximum inclination angles θ1o and θ2o of the groove opening and the groove bottom have a relationship of 1.50≦θ2o/θ1o≦2.00. 5. The wavelength λ1o of the outer edge portion of the groove opening has a relationship of 0.90≦λ2o/λ1o≦1.10 with respect to the wavelength λ2o of the outer edge portion of the groove bottom. A pneumatic tire as described in any one. 6. Any one of claims 1 to 5, wherein the amplitude A1o of the outer edge portion of the groove opening has a relationship of 1.00≤A2o/A1o≤2.00 with respect to the amplitude A2o of the outer edge portion of the groove bottom. A pneumatic tire as described in any one. The maximum distance L1o in the tire circumferential direction between the outer maximum amplitude position and the inner maximum amplitude position at the outer edge portion of the groove opening is equal to the outer maximum amplitude position and the inner maximum amplitude position at the outer edge portion of the groove bottom. The pneumatic tire according to any one of claims 1 to 6, having a relationship of 1.10 ≤ L2o/L1o ≤ 1.40 with respect to the maximum distance L2o in the tire circumferential direction from the amplitude position. The offset amount φoo of the outer maximum amplitude position at the outer edge portion of the groove opening and the groove bottom has a relationship of φoi<φoo with respect to the offset amount φoi of the inner maximum amplitude position. A pneumatic tire according to any one of the above. A maximum distance L1o in the tire circumferential direction between the outer maximum amplitude position and the inner maximum amplitude position at the outer edge of the groove opening is 0.50≦L1o/λ1o with respect to the wavelength λ1o of the outer edge. A pneumatic tire according to any one of the preceding claims having a relationship of 0.60. The groove wall angle α1oo at the outer maximum amplitude position of the outer edge portion of the groove opening satisfies the relation α2oo<α1oo with respect to the groove wall angle α2oo at the outer maximum amplitude position of the outer edge portion of the groove bottom. The pneumatic tire according to any one of claims 1 to 9 . The groove wall angles α1oo and α1oi at the outer maximum amplitude position and the inner maximum amplitude position of the outer edge portion of the groove opening have a relationship of α1oo<α1oi according to any one of claims 1 to 10 . pneumatic tires. The pneumatic tire according to any one of claims 1 to 11 , wherein the circumferential main groove is the outermost shoulder main groove in the tire width direction. The land portion on the outer side in the tire width direction defined by the circumferential main groove is a rib continuous in the tire circumferential direction, and
The pneumatic tire according to any one of claims 1 to 12 , wherein the land portion on the inner side in the tire width direction defined by the circumferential main groove comprises a plurality of lug grooves. A pneumatic tire comprising a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove,
Each of the groove opening and the groove bottom of the circumferential main groove has a zigzag shape or a wavy shape with amplitude in the tire width direction,
Define an outer maximum amplitude position that is convex outward in the tire width direction and an inner maximum amplitude position that is convex inward at the respective center lines of the groove opening and the groove bottom,
The outer maximum amplitude position of the center line of the groove opening is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the center line of the corresponding groove bottom , and
The maximum distance L2c in the tire circumferential direction between the outer maximum amplitude position and the inner maximum amplitude position on the center line of the groove bottom is 0.55≦L2c/λ2c with respect to the wavelength λ2c of the center line of the groove bottom. A pneumatic tire characterized by having a relationship of ≦0.65 . A pneumatic tire comprising a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove,
Each of the groove opening and the groove bottom of the circumferential main groove has a zigzag shape or a wavy shape with amplitude in the tire width direction,
An outer edge portion located on the outer side in the tire width direction is defined at each of the groove opening portion and the groove bottom portion, and the outer maximum amplitude position and the inner convex portion are convex to the outer side in the tire width direction at the outer edge portion. define the inner maximum amplitude position,
The outer maximum amplitude position of the outer edge portion of the groove opening is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the outer edge portion of the corresponding groove bottom , and
The pneumatic container, wherein the wavelength λ1o of the outer edge portion of the groove opening has a relationship of 0.95≦λ2o/λ1o≦1.10 with respect to the wavelength λ2o of the outer edge portion of the groove bottom. tire. A pneumatic tire comprising a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove,
Each of the groove opening and the groove bottom of the circumferential main groove has a zigzag shape or a wavy shape with amplitude in the tire width direction,
Define an outer maximum amplitude position that is convex outward in the tire width direction and an inner maximum amplitude position that is convex inward at the respective center lines of the groove opening and the groove bottom,
The outer maximum amplitude position of the center line of the groove opening is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the center line of the corresponding groove bottom , and
A pneumatic tire, wherein the wavelength λ1c of the center line of the groove opening has a relationship of 0.95≦λ2c/λ1c≦1.10 with respect to the wavelength λ2c of the center line of the groove bottom . A pneumatic tire comprising a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove,
Each of the groove opening and the groove bottom of the circumferential main groove has a zigzag shape or a wavy shape with amplitude in the tire width direction,
An outer edge portion located on the outer side in the tire width direction is defined at each of the groove opening portion and the groove bottom portion, and the outer maximum amplitude position and the inner convex portion are convex to the outer side in the tire width direction at the outer edge portion. define the inner maximum amplitude position,
The outer maximum amplitude position of the outer edge portion of the groove opening is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the outer edge portion of the corresponding groove bottom , and
A pneumatic tire , wherein the number of pitches of the outer edge portions of the groove opening is equal to the number of pitches of the outer edge portions of the groove bottom . A pneumatic tire comprising a circumferential main groove extending in the tire circumferential direction and land portions defined by the circumferential main groove,
Each of the groove opening and the groove bottom of the circumferential main groove has a zigzag shape or a wavy shape with amplitude in the tire width direction,
Define an outer maximum amplitude position that is convex outward in the tire width direction and an inner maximum amplitude position that is convex inward at the respective center lines of the groove opening and the groove bottom,
The outer maximum amplitude position of the center line of the groove opening is offset in the tire circumferential direction with respect to the outer maximum amplitude position of the center line of the corresponding groove bottom , and
A pneumatic tire , wherein the number of pitches of the center lines of the groove openings is equal to the number of pitches of the center lines of the groove bottoms .

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