JP2017165140A - Radial tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radial tire for a heavy load capable of suppressing deterioration of drainage performance during wearing tire chains as well as reduction of tire service life.SOLUTION: In rib rows 21 and 22 of a tread surface part 11, open sipes 31 and 32 that are respectively opened to a pair of circumferential grooves 12 to 14 to which both end parts in a tire width direction correspond, are formed with intervals in a tire circumferential direction, and opened to the central circumferential groove 12 located closest to a tire equator surface CL among the circumferential grooves 12 to 14, and in a plan view of the tread surface part 11, openings 31a and 32a of the open sipes 31 and 32 located closest to a virtual straight line L connecting a center part in the tire circumferential direction at the outer end in the tire width direction of one side lug groove 15 with the center part in the tire circumferential direction at the outer end in the tire width direction of the other side lug groove 16, are each formed at a position separated by 15% or more of a tread width TW on the tread surface part 11 in the tire circumferential direction from the virtual straight line L.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heavy duty radial tire.

  As a heavy-duty radial tire used in heavy-duty vehicles such as trucks and buses, a configuration in which a so-called rib lug pattern in which a circumferential groove and a lug groove are combined is formed on a tread surface is known. A plurality of circumferential grooves are formed in the tread tread surface portion in the tire circumferential direction and at intervals in the tire width direction. A plurality of lug grooves are formed in a shoulder land portion located on both sides in the tire width direction of the tread tread surface portion in the tire width direction and at intervals in the tire circumferential direction.

  For example, the following Patent Document 1 has a configuration in which open sipes are formed at intervals in the tire circumferential direction in a row of ribs partitioned by a pair of circumferential grooves adjacent in the tire width direction in the tread surface portion. It is disclosed. The open sipe spans between a pair of circumferential grooves, and both ends in the tire width direction open into the pair of circumferential grooves, respectively. In this case, the part located between the open sipes adjacent in the tire circumferential direction in the rib row constitutes a rib block defined by the open sipes and the circumferential grooves.

JP 2009-51453 A

  By the way, in the heavy-duty radial tire described above, a tire chain may be mounted when traveling on a road surface during snowfall or freezing. In this case, the tire chain is slackened in the tire circumferential direction, crosses the tread tread surface portion in the tire width direction, and both end portions in the tire width direction are locked in the lug grooves described above.

However, the above-described heavy duty radial tire still has room for improvement in terms of improving drainage performance when the tire chain is mounted. Specifically, when the tire chain is mounted, the tire chain is sandwiched between the tread tread portion and the road surface, so that a large ground pressure acts locally on the tread tread portion. Therefore, the rib row is swelled and deformed in the tire width direction so as to narrow the circumferential groove by being compressed inward in the tire radial direction.
At this time, in the rib block, the periphery of the corner formed by the open sipe and the circumferential groove is lower in rigidity than the other parts, so that the ground pressure in the tire width direction when the contact pressure acts through the tire chain is reduced. Large amount of deformation. Therefore, in the circumferential groove, around the corner of the rib block, there is a problem that drainage performance is deteriorated due to a decrease in groove volume.

  Moreover, there is a risk that the rib row may be plastically deformed (so-called chain sag) by continuing running with the tire chain mounted. In this case, since the rib row is not restored and deformed even after the tire chain is removed, the tire life is shortened.

  The present invention has been made in consideration of such circumstances, and provides a heavy-duty radial tire capable of suppressing a decrease in drainage performance at the time of mounting a tire chain and suppressing a decrease in tire life. With the goal.

  In order to solve the above problems and achieve such an object, the heavy-duty radial tire of the present invention is a heavy-duty radial tire in which a rib lug pattern is formed on a tread surface, and the rib lug pattern is A plurality of circumferential grooves extending in the tire circumferential direction and spaced apart in the tire width direction, and one side lug groove formed at one end in the tire width direction of the tread surface portion, And the other side lug groove formed at the other end of the tread tread surface portion in the tire width direction, and is defined by a pair of circumferential grooves adjacent to each other in the tire width direction of the tread tread surface portion. In the rib row, open sipes having both ends in the tire width direction that are opened separately in the pair of circumferential grooves are formed at intervals in the tire circumferential direction, and the tire equatorial plane is the most of the circumferential grooves. An opening is formed in a central circumferential groove located in the vicinity, and in the plan view of the tread tread surface portion, a tire is formed in the tire circumferential direction central portion at the outer end of the one side lug groove in the tire width direction and the one side lug groove. The opening portion of the open sipe that is located closest to a virtual straight line connecting the tire circumferential direction center portion of the other side lug groove located closest to the circumferential direction in the tire circumferential direction, It is formed at a position that is 15% or more away from the size in the tire width direction of the tread surface portion in the tire circumferential direction from the virtual straight line.

  Here, in a state where the tire chain is mounted on the heavy duty radial tire, the amount of slack in the tire circumferential direction of the portion of the tire chain that crosses the tread tread surface portion in the tire width direction (distance in the tire circumferential direction from the virtual straight line) ) Is generally preferably less than 15% of the size in the tire width direction (hereinafter referred to as the tread width). That is, when the amount of slack is 15% or more of the tread width, the adhesion between the tire chain and the heavy duty radial tire is lowered, and the necessary heavy traction performance such as the heavy duty radial tire slipping with respect to the tire chain is obtained. May not be obtained. On the other hand, when the amount of slack is extremely small, there is a risk that a large load acts on the tire chain.

Therefore, according to the configuration of the present invention, the opening portion of the open sipe in the central circumferential groove (hereinafter referred to as the central opening portion) is 15% or more of the tread width in the tread tread surface portion in the tire circumferential direction from the virtual straight line. Form at a distant position. As a result, in a state where the tire chain is mounted on the heavy duty radial tire, the corner portion (hereinafter referred to as the central corner portion) formed by the open sipe and the central circumferential groove in the rib row is the tread tread portion in the tire radial direction. It is arrange | positioned in the position which does not overlap with a tire chain in the planar view seen from. Therefore, it is possible to suppress the local contact pressure from acting locally on the central corner portion via the tire chain, so that the bulging deformation of the central corner portion in the tire width direction can be suppressed. As a result, it is possible to suppress a decrease in the groove volume of the central circumferential groove when the tire chain is mounted, and to suppress a decrease in drainage performance.
Moreover, since it can suppress that a contact pressure acts locally on a central corner part via a tire chain, the chain | stretching of a rib row | line | column can be suppressed. That is, after removing the tire chain, the rib row can be restored and deformed, and the decrease in tire life can be suppressed. In the tread tread portion, the above-described operation and effect are remarkably achieved by separating the central opening located near the tire equator surface where the contact pressure is most likely to act from the virtual straight line.

The ratio of the groove width to the groove depth of the central circumferential groove may be set to 1.0 or more.
In this case, since the ratio of the groove width to the groove depth of the central circumferential groove is set to 1.0 or more, even if the rib row (central corner) bulges and deforms in the tire width direction, It is possible to suppress the directional groove from being blocked by the rib row. As a result, reduction in drainage performance and tire life can be suppressed.

Moreover, the closed sipes which the both ends of the extending direction terminate in the said rib block may be formed in the rib block divided into the said open sipes adjacent to a tire circumferential direction among the said rib row | line | columns.
In this case, since the closed sipes are formed in the rib blocks, it is possible to secure the drainage performance and edge effect due to the sipes, while suppressing a decrease in the rigidity of the rib blocks due to the sipe formation as compared with the case of forming the open sipes.

Further, two closed sipes may be formed in the rib block at intervals in the tire circumferential direction.
In this case, by forming two closed sipes in the same rib block, it is possible to secure the drainage performance and edge effect by sipes while suppressing the bulging deformation of the rib rows in the tire width direction due to the increase of sipes.

A plurality of rib rows are formed in the tread tread surface at intervals in the tire width direction, and a plurality of rib rows adjacent to one in the tire width direction with respect to the central circumferential groove. The opening of the open sipe formed in one rib row has both ends in the extending direction in the closed sipe formed in the second rib row adjacent to the other in the tire width direction with respect to the central circumferential groove. May be arranged at a position away from each other in the tire circumferential direction.
In this case, in the second rib row, the open sipe formed in the first rib row is located at a position where both ends in the extending direction in the closed sipe are located and a portion having relatively low rigidity is avoided in the tire circumferential direction. The central opening is arranged. This ensures the rigidity of the portion of the rib block of the second rib row that faces the central opening of the open sipe formed in the first rib row in the tire width direction, and bulge deformation in the tire width direction Can be suppressed. Therefore, even if the central corner portion of the rib block in the first rib row is bulged and deformed in the tire width direction, the central circumferential groove can be prevented from being blocked by the rib row.

Further, among the plurality of rib rows, the opening portion of the open sipe formed in the first rib row is located away from the closed sipe formed in the second rib row in the tire circumferential direction. May be arranged.
In this case, in the second rib row, the open sipe formed in the first rib row at a position where the entire extending direction in the closed sipe is located and a portion having a relatively low rigidity is avoided in the tire circumferential direction. A central opening will be placed. This ensures the rigidity of the portion of the rib block of the second rib row that faces the central opening of the open sipe formed in the first rib row in the tire width direction, and bulge deformation in the tire width direction Can be suppressed. Therefore, even if the central corner portion of the rib block in the first rib row is bulged and deformed in the tire width direction, the central circumferential groove can be reliably suppressed from being blocked by the rib row.

The bottom surface of the central circumferential groove may be a smooth surface.
By the way, when a protrusion for preventing stone biting or the like is formed on the bottom surface of the central circumferential groove, when the rib row is deformed in the tire width direction, a portion of the rib row located near the tread tread surface portion is By locally deforming the contact portion with the protrusion as a fulcrum, the opening of the central circumferential groove (opening on the tread surface) may be blocked.
On the other hand, by forming the bottom surface of the central circumferential groove in a smooth surface, the height in the tire radial direction in the rib row is secured, and the portion located in the vicinity of the tread tread surface portion in the rib row is locally Deformation can be suppressed. In this case, a central portion in the tire radial direction in the rib row mainly bulges and deforms in the tire width direction. As a result, it is possible to reliably prevent the opening of the central circumferential groove from being blocked, and to suppress a decrease in drainage performance due to the central circumferential groove when the tire chain is mounted.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing the fall of the drainage performance at the time of mounting | wearing of a tire chain, the fall of a tire life can be suppressed.

In one Embodiment which concerns on this invention, it is a top view which shows a part of tread surface part of a tire.

Hereinafter, an embodiment of a heavy duty radial tire according to the present invention will be described with reference to the drawings.
In addition, the chain line CL in a figure has shown the tire equator surface. The tire 1 of the present embodiment has a left-right asymmetric pattern with the tire equatorial plane CL interposed therebetween. In the following description, the left side of the drawing with respect to the tire equatorial plane CL will be described as one side in the tire width direction, and the right side in the drawing will be described as the other side in the tire width direction.

  As shown in FIG. 1, the tire 1 of this embodiment is a heavy-duty radial tire used in heavy-duty vehicles such as trucks and buses. A so-called rib lug pattern in which the circumferential grooves 12 to 14 and the lug grooves 15 and 16 are combined is formed on the tread surface 11 of the tire 1.

In the tire 1 of the present embodiment, a known bead core, a carcass ply, a steel belt, and the like (not shown) are embedded.
The tread tread portion 11 described above is an industry standard for each region where the tire 1 is produced or used (for example, “JATMA Year Book” in Japan, “TRA Year Book” in the United States, “ETRTO Standard Manual” in Europe). ”Etc.) means the contact surface of the tread part with the specified internal pressure and specified load.

  The circumferential grooves 12 to 14 are each formed over the entire circumference in the tire circumferential direction. Three circumferential grooves 12 to 14 are formed in the tread tread surface portion 11 at intervals in the tire width direction. Specifically, each of the circumferential grooves 12 to 14 has a central circumferential groove 12 located on the tire equatorial plane CL, and a one-side circumferential groove 13 located on one side in the tire width direction with respect to the central circumferential groove 12. And the other circumferential groove 14 located on the other side in the tire width direction with respect to the central circumferential groove 12.

  The central circumferential groove 12 is formed in a wavy shape meandering in the tire width direction in a plan view of the tread tread portion 11 viewed from the tire radial direction. The groove width of the central circumferential groove 12 is equal to or greater than the groove depth. That is, in the central circumferential groove 12, the ratio of the groove width to the groove depth is 10 or more. In the example of FIG. 1, the central circumferential groove 12 is located on the tire equatorial plane CL, but is not limited thereto. That is, the central circumferential groove 12 may be any one that is located closest to the tire equatorial plane CL among the circumferential grooves 12 to 14.

  Moreover, the area | region other than the slip sign which is not illustrated among the bottom faces of the center circumferential groove | channel 12 is formed in the smooth surface over the whole. That is, no protrusions or the like for preventing stone biting are formed on the bottom surface of the central circumferential groove 12 of the present embodiment. A plurality of slip signs are formed in the central circumferential groove 12 at intervals in the tire circumferential direction. Each slip sign bulges outward in the tire radial direction and bridges the inner side surfaces facing each other in the tire width direction in the central circumferential groove 12. The slip sign may be formed on the bottom surface of the one-side circumferential groove 13 or the other-side circumferential groove 14. In this case, the bottom surface of the central circumferential groove 12 is a smooth surface over the entire tire circumferential direction.

  The one side circumferential groove 13 and the other side circumferential groove 14 are formed in a wavy shape meandering in the tire width direction in a plan view as seen from the tire radial direction. In the example of FIG. 1, the distance in the tire width direction from the tire equator plane CL to the one side circumferential groove 13 is equal to the distance in the tire width direction from the tire equator plane CL to the other side circumferential groove 14. . The circumferential grooves 12 to 14 may be formed linearly in the tire circumferential direction. In the present embodiment, the groove depths of the circumferential grooves 12 to 14 are equal to each other. However, the dimensions and shapes of the circumferential grooves 12 to 14 can be appropriately changed.

A plurality of rib rows 21 and 22 are defined in the tread tread portion 11 by the circumferential grooves 12 to 14. In the present embodiment, the rib rows 21 and 22 are partitioned by the one-side rib row 21 defined by the central circumferential groove 12 and the one-side circumferential groove 13, and the central circumferential groove 12 and the other-side circumferential groove 14. The other side rib row 22. Each rib row 21, 22 extends in a strip shape over the entire circumference in the tire circumferential direction.
Further, a portion of the tread tread surface portion 11 that is located on one side in the tire width direction with respect to the one-side circumferential groove 13 constitutes a one-side shoulder land portion (one-side end portion) 25. A portion of the tread tread portion 11 that is located on the other side in the tire width direction with respect to the other-side circumferential groove 14 constitutes the other-side shoulder land portion (the other-side end portion) 26.

  The lug grooves 15 and 16 described above are the one side lug groove 15 formed in the one side shoulder land portion 25 and the other side lug groove 16 formed in the other side shoulder land portion 26. A plurality of lug grooves 15 and 16 are formed on the corresponding shoulder land portions 25 and 26 at intervals in the tire circumferential direction.

  The one side lug groove 15 extends in the tire width direction. Specifically, one end portion in the tire width direction of the one side lug groove 15 is opened from the one side shoulder land portion 25 to one side in the tire width direction. The other side end portion in the tire width direction of the one side lug groove 15 extends toward one side (upper side in FIG. 1) in the tire circumferential direction toward the other side in the tire width direction. The other side end portion in the tire width direction of the one side lug groove 15 terminates in the one side shoulder land portion 25.

  The other side lug groove 16 extends in the tire width direction. Specifically, the other side end portion in the tire width direction of the other side lug groove 16 is opened from the other side shoulder land portion 26 to the other side in the tire width direction. One end portion in the tire width direction of the other side lug groove 16 extends toward the other side (lower side in FIG. 1) in the tire circumferential direction toward one side in the tire width direction. One end in the tire width direction of the other side lug groove 16 terminates in the other side shoulder land portion 26.

  In the present embodiment, the one side lug grooves 15 and the other side lug grooves 16 are arranged at the same arrangement pitch with the positions in the tire circumferential direction being different from each other. However, the position of the lug grooves 15 and 16 in the tire circumferential direction and the arrangement pitch can be changed as appropriate. For example, the lug grooves 15 and 16 may be arranged at equivalent positions in the tire circumferential direction.

  Each of the rib rows 21 and 22 described above is formed with an open sipe (one side open sipe 31 and the other side open sipe 32). A plurality of open sipes 31 and 32 are arranged at intervals in the tire circumferential direction in the corresponding rib rows 21 and 22.

  The one-side open sipe 31 extends in the tire width direction in the one-side rib row 21. Specifically, the one-side open sipes 31 meander in the tire circumferential direction and extend to one side in the tire circumferential direction toward the other side in the tire width direction. The other side end in the tire width direction of the one-side open sipe 31 is open in the central circumferential groove 12 (a central opening (opening) 31a in FIG. 1). One end in the tire width direction of the one-side open sipe 31 is open in the one-side circumferential groove 13 (one-side opening 31b in FIG. 1).

  The other side open sipe 32 extends in the tire width direction in the other side rib row 22. Specifically, the other-side open sipes 32 meander in the tire circumferential direction and extend to one side in the tire circumferential direction toward the other side in the tire width direction. One end in the tire width direction of the other side open sipe 32 is opened in the central circumferential groove 12 (a central opening (opening) 32a in FIG. 1). The other side end in the tire width direction of the other side open sipe 32 is opened in the other side circumferential groove 14 (the other side opening 32b in FIG. 1). Moreover, it is preferable that the groove depth of each open sipe 31 and 32 is formed below the groove depth of each circumferential groove | channel 12-14.

  In the present embodiment, the one side open sipe 31 and the other side open sipe 32 are arranged at the same arrangement pitch with the positions in the tire circumferential direction being different from each other. However, the position in the tire circumferential direction and the arrangement pitch in the open sipes 31 and 32 can be changed as appropriate. In this case, if the central openings 31a and 32a opened in the central circumferential groove 12 of the open sipes 31 and 32 do not face each other in the tire width direction, for example, the one side open sipes 31 and the other side open sipes 32 At least a part may be opposed in the tire width direction. Moreover, the shape, dimension, etc. of each open sipe 31, 32 can be suitably changed if both ends in the tire width direction are open in the corresponding circumferential grooves 12-14.

  In the one-side rib row 21 described above, a portion located between the one-side open sipes 31 adjacent in the tire circumferential direction constitutes a one-side rib block 41. A plurality of one-side closed sipes 42a and 42b are formed in the one-side rib block 41 at intervals in the tire circumferential direction. Each one-side closed sipes 42 a and 42 b end in the one-side rib block 41 at both ends in the extending direction. Each of the one-side closed sipes 42a, 42b formed on the same one-side rib block 41 is partially opposed in the tire circumferential direction.

  Of each of the one-side closed sipes 42a and 42b, portions facing each other in the tire circumferential direction (hereinafter referred to as facing portions) extend in parallel with each other. In this embodiment, the opposing part of each one side closed sipes 42a, 42b extends toward one side in the tire circumferential direction from one side in the tire width direction toward the other side. The other side end in the tire width direction of the one side closed sipe 42a located on one side in the circumferential direction is bent to one side in the circumferential direction with respect to the facing portion. Moreover, the one side edge part of the tire width direction of the one side closed sipe 42b located in the other side of the circumferential direction is bent by the other side of the circumferential direction with respect to the opposing part.

  Further, in the other-side rib row 22, a portion located between the other-side open sipes 32 adjacent in the tire circumferential direction constitutes the other-side rib block 43. On the other side rib block 43, a plurality of other side closed sipes 44a, 44b are formed at intervals in the tire circumferential direction. Each of the other side closed sipes 44 a and 44 b terminates in the other side rib block 43 at both ends in the extending direction. Each of the other side closed sipes 44a and 44b is partially opposed in the tire circumferential direction.

  Of each of the other side closed sipes 44a and 44b, opposing portions in the tire circumferential direction (hereinafter referred to as opposing portions) extend in parallel with each other. In this embodiment, the opposing part of each other side closed sipes 44a, 44b extends toward one side in the tire circumferential direction from one side in the tire width direction toward the other side. The other side end portion in the tire width direction of the other side closed sipes 44a located on one side in the circumferential direction is bent toward one side in the circumferential direction with respect to the facing portion. Moreover, the one side edge part of the tire width direction of the other side closed sipe 44b located in the other side of the circumferential direction is bent by the other side of the circumferential direction with respect to the opposing part.

  Here, in the present embodiment, among the open sipes 31 and 32, the one side lug groove 15 and the one side lug groove 15 are the most in the tire circumferential direction in the plan view of the tread tread portion 11. The central openings 31a, 32a of the open sipes 31, 32 located closest to the imaginary straight line L connecting the other one side lug grooves 16 arranged in the vicinity have the following ranges in the rib rows 21, 22: Is set to That is, the central openings 31a and 32a are, in a plan view of the tread tread portion 11, in the tire circumferential direction from the intersection O between the virtual straight line L and the tire equatorial plane CL described above, in the tread width TW ( It is formed in the range of 15% to 50% of the size in the tire width direction. In the present embodiment, the imaginary straight line L is the tire in the tire circumferential direction center portion at one end portion (outer end) in the tire width direction of one one side lug groove 15 and the tire in one other side lug groove 16. It connects with the center part of the tire peripheral direction in the other side edge part (outer end) of the width direction.

Further, the central opening 31a of the one-side open sipe 31 is formed at a position separated from at least both ends of the other-side closed sipes 44a and 44b in the tire circumferential direction. In the example of FIG. 1, the central opening 31 a of the one-side open sipe 31 is formed at a position away from the entire other-side closed sipes 44 a and 44 b in the tire circumferential direction.
Further, the central opening 32a of the other-side open sipe 32 is formed at a position away from at least both ends of the one-side closed sipes 42a and 42b in the tire circumferential direction. In the example of FIG. 1, the central opening 32a of the other side open sipe 32 is formed at a position away from the entire one side closed sipe 42a, 42b in the tire circumferential direction.

  By the way, a tire chain C is detachably attached to the tire 1 of the present embodiment so as to cross the tread tread portion 11 in the tire width direction. The tire chain C crosses the tread tread portion 11 while being slackened in the tire circumferential direction (one side in the example of FIG. 1), and both end portions in the tire width direction are closest to each other in the tire circumferential direction, for example. 15 and the other side lug groove 16 (one one side lug groove 15 and one other side lug groove 16). Note that the amount of slack in the tire circumferential direction of the portion of the tire chain C that traverses the tread tread portion 11 in the tire width direction (distance in the tire circumferential direction from the intersection point O in the example of FIG. 1) is generally the tread width TW. Less than 15% is preferred. That is, when the amount of slack is 15% or more of the tread width TW, the adhesion between the tire chain C and the tire 1 becomes low, and the necessary traction performance such as the tire 1 idling with respect to the tire chain C is obtained. There is a risk of not being able to. On the other hand, when the amount of slack is extremely small, a large load may be applied to the tire chain C.

Therefore, in the present embodiment, the central openings 31a and 32a of the open sipes 31 and 32 are formed at positions separated from the intersection point O by 15% or more of the tread width TW in the tire circumferential direction.
According to this configuration, in a state where the tire chain C is mounted on the tire 1, the central corners of the rib blocks 41 and 43 (the corners formed by the central circumferential groove 12 and the open sipes 31 and 32) are in plan view. It is arranged at a position that does not overlap the tire chain C. Therefore, local contact pressure can be prevented from acting locally on the central corners of the rib blocks 41 and 43 via the tire chain C, so that the central corners of the rib blocks 41 and 43 bulge in the tire width direction. Deformation can be suppressed. As a result, a decrease in the groove volume of the central circumferential groove 12 when the tire chain C is mounted can be suppressed, and a decrease in drainage performance can be suppressed.
In addition, since the contact pressure can be prevented from acting locally on the central corner portions of the rib blocks 41 and 43 via the tire chain C, the chain of the rib rows 21 and 22 can be suppressed. That is, after removing the tire chain C, the rib rows 21 and 22 can be restored and deformed, and a reduction in tire life can be suppressed. In the tread tread portion 11, the above-described operation and effect are remarkably achieved by separating the central openings 31a and 32a located near the tire equator surface CL where the contact pressure is most likely to act from the intersection O.

  On the other hand, in the present embodiment, the central openings 31a and 32a of the open sipes 31 and 32 are formed in a range of 50% or less of the tread width TW with respect to the intersection point O in the tire circumferential direction. The number of 32 can be secured. Thereby, the drainage performance and edge effect by the open sipes 31 and 32 are securable.

  In this embodiment, since the ratio of the groove width to the groove depth of the central circumferential groove 12 is set to 1.0 or more, the rib rows 21 and 22 (the central corners of the rib blocks 41 and 43) are assumed to be tires. Even if bulging and deforming in the width direction, the central circumferential groove 12 can be prevented from being blocked by the rib rows 21 and 22. As a result, a decrease in drainage performance and tire life can be reliably suppressed.

  In this embodiment, since the closed sipes 42a, 42b, 44a, and 44b are formed on the rib blocks 41 and 43, the rigidity of the rib blocks 41 and 43 due to the sipe formation is suppressed compared to the case where the open sipes are formed. Above, drainage performance and edge effect can be ensured.

  In this embodiment, by forming two closed sipes 42a, 42b, 44a, 44b in each rib block 41, 43, the bulging deformation in the tire width direction of the rib rows 21, 22 due to an increase in sipes is suppressed. In addition, drainage performance and edge effect by sipe can be ensured.

In the present embodiment, among the rib rows adjacent to both sides across the central circumferential groove 12, the central opening portion of the open sipe formed in the first rib row is formed on the entire closed sipe formed in the second rib row. On the other hand, it was set as the structure currently formed in the position away in the tire circumferential direction.
According to this configuration, in the second rib row, the central opening of the open sipe formed in the first rib row is located at a position where the closed sipe is located and a portion having relatively low rigidity is avoided in the tire circumferential direction. Will be placed. Therefore, of the rib block of the second rib row, the rigidity of the portion facing the central opening of the open sipe formed in the first rib row in the tire width direction is secured, and the bulging deformation in the tire width direction is suppressed. it can. Therefore, even if the central corner portion of the rib block in the first rib row bulges and deforms in the tire width direction, the central circumferential groove 12 can be prevented from being blocked by the rib rows 21 and 22.

By the way, when a protrusion for preventing stone biting is formed on the bottom surface of the central circumferential groove 12, when the rib rows 21 and 22 are deformed in the tire width direction, the tread tread portion of the rib rows 21 and 22 is formed. There is a possibility that the opening portion (opening portion on the tread tread portion 11) of the central circumferential groove 12 may be blocked by the local deformation of the portion located in the vicinity of 11 with the contact portion with the projection as a fulcrum. is there.
On the other hand, in this embodiment, since the bottom surface of the central circumferential groove 12 is formed as a smooth surface, the height in the tire radial direction in the rib rows 21 and 22 is secured, and the rib rows 21 and 22 It can suppress that the part located in the vicinity of the tread tread part 11 deform | transforms locally. In this case, of the rib rows 21 and 22, the central portion in the tire radial direction mainly bulges and deforms in the tire width direction. As a result, it is possible to reliably prevent the opening of the central circumferential groove 12 from being blocked, and to prevent a decrease in drainage performance due to the central circumferential groove 12 when the tire chain C is mounted.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, the configuration including the three circumferential grooves 12 to 14 has been described. However, the configuration is not limited thereto, and two or more circumferential grooves may be provided.
In the above-described embodiment, the configuration in which only the central openings 31a and 32a of the open sipes 31 and 32 are formed at positions separated by 15% or more of the tread width TW in the tire circumferential direction from the intersection point O has been described. I can't. That is, of the open sipes 31 and 32, the openings that open to the one-side circumferential groove 13 and the other-side circumferential groove 14 are formed at positions that are separated from the intersection O in the tire circumferential direction by 15% or more of the tread width TW. It doesn't matter.

In the above-described embodiment, the configuration in which the closed sipes 42a, 42b, 43a, 43b are inclined and extend in the tire width direction has been described. However, the shape, dimensions, and the like of the closed sipes 42a, 42b, 43a, 43b are appropriately changed. Is possible. In this case, the closed sipes 42a, 42b, 43a, 43b may be formed linearly in the tire circumferential direction or linearly in the tire width direction, for example.
The number of closed sipes on the same rib blocks 41 and 43 can be changed as appropriate.
In the above-described embodiment, the case where the open sipes 31 and 32 located closest to the virtual straight line L among the open sipes 31 and 32 intersect with the virtual straight line L is described, but the present invention is not limited thereto.

  In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described modified examples may be appropriately combined.

  While suppressing the fall of the drainage performance at the time of mounting | wearing of a tire chain, the fall of a tire life can be suppressed.

DESCRIPTION OF SYMBOLS 1 ... Radial tire for heavy loads 11 ... Tread tread part 12 ... Center circumferential groove (circumferential groove)
13. One side circumferential groove (circumferential groove)
14 ... other side circumferential groove (circumferential groove)
15 ... one side lug groove 16 ... other side lug groove 21 ... one side rib row (rib row, first rib row, second rib row)
22 ... the other side rib row (rib row, first rib row, second rib row)
25. One side shoulder land (one side end)
26 ... Shoulder land on the other side (end on the other side)
31 ... One side open sipe (open sipe)
31a ... Central opening (opening)
32 ... Open sipe on the other side (open sipe)
32a ... Central opening (opening)
41 ... One side rib block (rib block)
42a, 42b ... One side closed sipes (closed sipes)
43 ... Rib block on the other side (rib block)
44a, 44b ... the other side closed sipes (closed sipes)

Claims (7)

A heavy duty radial tire having a rib lug pattern formed on the tread surface,
The rib lug pattern is
A plurality of circumferential grooves formed extending in the tire circumferential direction and spaced in the tire width direction;
One side lug groove formed at one end of the tread tread surface in the tire width direction;
The other side lug groove formed at the end of the other side in the tire width direction in the tread surface portion,
The rib rows defined by the pair of circumferential grooves adjacent to each other in the tire width direction in the tread tread surface portion have open sipes in which both ends in the tire width direction are individually opened in the pair of circumferential grooves. Formed at intervals in the direction,
Among the circumferential grooves, the tire circumferential direction opens at a central circumferential groove located closest to the tire equatorial plane and at the outer end in the tire width direction of the one side lug groove in a plan view of the tread tread surface portion. Closest to the imaginary straight line connecting the central part of the tire and the central part in the tire circumferential direction at the outer end in the tire width direction of the other side lug groove located closest to the one side lug groove in the tire circumferential direction The opening portion of the open sipe located in the tire is formed at a position away from the virtual straight line in the tire circumferential direction by 15% or more of the size in the tire width direction of the tread tread surface portion. Radial tire.   The radial tire for heavy loads according to claim 1, wherein a ratio of a groove width to a groove depth of the central circumferential groove is set to 1.0 or more.   Among the rib rows, the rib blocks defined in the open sipes adjacent in the tire circumferential direction are formed with closed sipes whose both ends in the extending direction terminate in the rib blocks. The radial tire for heavy loads according to claim 1 or 2.   The radial tire for heavy loads according to claim 3, wherein two closed sipes are formed in the rib block at intervals in the tire circumferential direction. A plurality of rib rows are formed in the tread tread portion at intervals in the tire width direction,
Of the plurality of rib rows, the opening portion of the open sipe formed in the first rib row adjacent to one side in the tire width direction with respect to the central circumferential groove is a tire with respect to the central circumferential groove. 4. The tire according to claim 3, wherein the closed sipe formed in the second rib row adjacent to the other in the width direction is disposed at a position separated in the tire circumferential direction from both ends in the extending direction. Item 5. A heavy-duty radial tire according to item 4.   Of the plurality of rib rows, the opening portion of the open sipe formed in the first rib row is disposed at a position away from the closed sipe formed in the second rib row in the tire circumferential direction. The radial tire for heavy loads according to claim 5, wherein the radial tire is used.   The radial tire for heavy loads according to any one of claims 1 to 6, wherein a bottom surface of the central circumferential groove is a smooth surface.

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