JP2020006878A - Pneumatic tire - Google Patents

Abstract

To improve dry performance while assuring snow performance.SOLUTION: A pneumatic tire comprising: a circumferential direction narrow groove 40 which is formed on a tread surface, and extends in a tire circumferential direction; a lug groove 50 which is formed on the tread surface, extends in a tire width direction, and communicates with the circumferential direction narrow groove 40; an intersection bottom upper part 71 which is formed at an intersection part 48A at which the circumferential direction narrow groove 40 and the lug groove 50 intersect with each other; a width direction bottom upper part 72 which is provided on the lug groove 50, and is connected to the intersection bottom upper part 71; and a circumferential direction bottom upper part 73 which is provided on the circumferential direction narrow groove 40, and is connected to the intersection bottom upper part 71. A groove bottom 42a of the circumferential direction narrow groove 40 is so made as to be a reference, a height Ha of the width direction bottom upper part 72 and a height Hr of the intersection bottom intersection upper part 71 satisfy a relationship of Ha<Hr, and a height Hb of the circumferential direction bottom upper part 73 and the height Hr of the intersection bottom intersection upper part 71 satisfy a relationship of Hb<Hr.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a pneumatic tire.

  In pneumatic tires, grooves are formed on the tread surface for the purpose of ensuring drainage, etc. However, since grooves lead to a decrease in rigidity of land portions, some conventional pneumatic tires include Patent Document 1 and As disclosed in Japanese Patent Application Laid-Open No. H11-163, there is a method in which the bottom portion is provided in the groove to secure the rigidity of the land portion while providing the groove in a desired form. Further, some conventional pneumatic tires have an upper bottom provided in a groove for the purpose of causing a driver to recognize a wear limit, as in Patent Document 3.

Japanese Patent No. 4665626 Japanese Patent No. 542135 JP 2005-67407 A

  Here, when traveling on snow and ice surfaces with vehicles equipped with summer tires or all season tires that are mainly used on snow and ice surfaces or roads other than off-road, it is necessary to attach a tire chain to pneumatic tires and drive There is. Since tire chains are often mounted on the driving wheels of vehicles, when traveling on snowy and icy roads with vehicles that have tire chains mounted on the driving wheels, pneumatic tires other than the driving wheels must be mounted without the tire chains. It will roll on snow and ice. Therefore, conventional summer tires and all-season tires sometimes have a tread pattern in which snow performance, which is steering stability when traveling on snowy and icy roads, is considered to some extent.

  For example, as a groove formed on the tread surface, a circumferential narrow groove extending in the tire circumferential direction is provided, and by connecting the lug groove extending in the tire width direction and the circumferential narrow groove, a decrease in rigidity of the land portion is suppressed as much as possible. In addition, the edge component can be increased. Thereby, snow performance can be improved while suppressing a decrease in dry performance, which is steering stability when traveling on a dry road surface.

  However, when the lug grooves communicate with the circumferential narrow grooves, the rigidity of the land portion is inevitably reduced, and the dry performance is reduced. For this reason, with the recent improvement in vehicle performance, it has been desired to improve dry performance while ensuring snow performance.

  The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving dry performance while ensuring snow performance.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to one aspect of the present invention includes a circumferential narrow groove formed in a tread surface and extending in a tire circumferential direction, and a circumferential narrow groove formed in the tread surface. A lug groove extending in the tire width direction and communicating with the circumferential narrow groove, a cross bottom upper portion formed at an intersection where the circumferential narrow groove intersects with the lug groove, and provided at the lug groove. A crosswise bottom upper portion connected to the cross bottom upper portion; and a circumferential bottom upper portion provided in the circumferential narrow groove and connected to the cross bottom upper portion, with reference to the groove bottom of the circumferential narrow groove. And the height Ha of the upper part in the width direction and the height Hr of the upper part of the intersection bottom satisfy a relationship of Ha <Hr, and the height Hb of the upper part in the circumferential direction and the height Hr of the upper part of the intersection bottom Satisfy the relationship of Hb <Hr.

  Further, in the pneumatic tire according to one aspect of the present invention, the height Ha of the upper portion in the width direction and the height Hr of the upper portion of the intersection bottom are (1.75 × Ha) ≦ Hr ≦ (2.25). × Ha).

  Further, in the pneumatic tire according to one aspect of the present invention, the height Hb of the upper part in the circumferential direction and the height Hr of the upper part of the intersection bottom are (1.75 × Hb) ≦ Hr ≦ (2.25). × Hb).

  In the pneumatic tire according to one aspect of the present invention, the groove width Wg1 of the lug groove and the length La in the tire width direction of the upper part in the width direction bottom are (0.5 × Wg1) ≦ La ≦ ( It is preferable to satisfy the relationship of 1.5 × Wg1).

  Further, in the pneumatic tire according to one aspect of the present invention, the groove width Wg2 of the circumferential narrow groove and the length Lb of the circumferential bottom upper portion in the tire circumferential direction are (0.5 × Wg2) ≦ Lb. It is preferable to satisfy the relationship of ≦ (1.5 × Wg2).

  Further, in the pneumatic tire according to one aspect of the present invention, the groove depth Dg1 of the circumferential narrow groove and the height Ha of the bottom in the width direction are (0.15 × Dg1) ≦ Ha ≦ (0 .35 × Dg1).

  Further, in the pneumatic tire according to one aspect of the present invention, the groove depth Dg1 of the circumferential narrow groove and the height Hb of the circumferential bottom upper portion are (0.15 × Dg1) ≦ Hb ≦ (0 .35 × Dg1).

  Further, in the pneumatic tire according to one aspect of the present invention, the height Ha of the upper portion in the width direction and the height Hb of the upper portion in the circumferential direction are in a relationship of 0.75 ≦ Ha / Hb ≦ 1.25. It is preferable to satisfy the following.

  Further, in the pneumatic tire according to one aspect of the present invention, the height Hr of the upper cross bottom, the height Ha of the upper width direction bottom, and the height Hb of the upper lower circumferential direction are [1. 75 × {(Ha + Hb) / 2}] ≦ Hr ≦ [2.25 × {(Ha + Hb) / 2}].

  According to the present invention, at the connecting portion where the lug groove and the circumferential narrow groove intersect, the lug groove has a width bottom upper part, and the circumferential narrow groove has a circumferential bottom upper part, and the lug groove and the circumferential narrow groove are formed. Since the cross bottom upper part where the width direction bottom upper part and the circumferential bottom upper part are connected is formed at the intersection part with the direction narrow groove, the rigidity of the land part near the connection part between the lug groove and the circumferential direction narrow groove is reduced. Can be secured. Thus, it is possible to suppress a decrease in dry performance, which is steering stability when traveling on a dry road surface, due to a decrease in rigidity of the land portion. Therefore, it is possible to secure the dry performance by securing the rigidity of the land portion where the circumferential narrow groove is formed by each bottom upper portion, while securing the snow performance by the edge effect by forming the circumferential narrow groove. it can. Moreover, according to the present invention, the height Hr of the upper cross bottom with respect to the groove bottom of the circumferential narrow groove is formed to be higher than the height Ha of the upper width direction bottom and the height Hb of the upper circumferential direction bottom. ing. For this reason, in the connecting portion between the lug groove and the circumferential narrow groove, a decrease in rigidity of the land portion due to the formation of the outer circumferential narrow groove can be further suppressed. As a result, it is possible to improve dry performance while ensuring snow performance.

FIG. 1 is a meridional sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view of a tread portion of the pneumatic tire according to the embodiment of the present invention. FIG. 3 is a detailed view of a portion A in FIG. FIG. 4 is a perspective view showing a connecting portion between the outer circumferential narrow groove shown in FIG. 3 and the first lug groove. FIG. 5 is a sectional view taken along line BB of FIG. FIG. 6 is a view taken in the direction of the arrows CC in FIG. FIG. 7 is a detailed view of a portion D in FIG. FIG. 8 is a cross-sectional view in the tire width direction of FIG. FIG. 9 is a table showing the results of a performance evaluation test of the pneumatic tire according to the example of the present invention. FIG. 10 is a table showing the results of a performance evaluation test of the pneumatic tire according to the example of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the embodiment. The components of this embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Further, the plurality of modified examples described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a meridional sectional view of the pneumatic tire according to the present embodiment. FIG. 2 is a plan view of a tread portion of the pneumatic tire according to the present embodiment.

  In the following description, the tire radial direction refers to a direction perpendicular to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inside refers to the side toward the rotation axis in the tire radial direction and the tire radial direction outside. Indicates a side away from the rotation axis in the tire radial direction. In addition, the tire circumferential direction refers to a circumferential direction around the rotation axis as a central axis. The tire width direction refers to a direction parallel to the rotation axis, the inside in the tire width direction refers to the side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the outside in the tire width direction refers to the tire width direction. The side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane orthogonal to the rotation axis of the pneumatic tire 1 and passing through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL is the center of the pneumatic tire 1 in the tire width direction. The center line in the tire width direction, which is the position, matches the position in the tire width direction. The tire equatorial line refers to a line on the tire equatorial plane CL and along the tire circumferential direction of the pneumatic tire 1, and in the present embodiment, is denoted by the same reference numeral “CL” as the tire equatorial plane.

  As shown in FIG. 1, the pneumatic tire 1 of the present embodiment has a tread portion 2, shoulder portions 3 on both sides thereof, and a sidewall portion 4 and a bead portion 5 that are successively continued from each shoulder portion 3. ing. The pneumatic tire 1 includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

  The tread portion 2 is made of a rubber material (tread rubber), and is exposed on the outermost side in the tire radial direction of the pneumatic tire 1, and its outer peripheral surface becomes the contour of the pneumatic tire 1. The outer peripheral surface of the tread portion 2 is a surface that can mainly come into contact with a road surface during traveling, and is configured as a tread surface 10.

  The shoulder portions 3 are portions on both outer sides in the tire width direction of the tread portion 2. The sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire 1. The bead portion 5 has a bead core 15 and a bead filler 16. The bead core 15 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 16 is a rubber material disposed in a space formed by folding the end of the carcass layer 6 in the tire width direction at the position of the bead core 15.

  Each end of the carcass layer 6 in the tire width direction is folded back from the inner side in the tire width direction to the outer side in the tire width direction by a pair of bead cores 15, and is wound around the tire in a toroidal manner in the tire circumferential direction to form a tire skeleton. Things. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged side by side at an angle with respect to the tire circumferential direction at a certain angle in the tire circumferential direction while being along the tire meridian direction, and coated with coat rubber. The carcass cord is made of, for example, organic fibers such as polyester, rayon, and nylon. The carcass layer 6 is provided as at least one layer.

  The belt layer 7 has a multilayer structure in which at least two layers of belts 7a and 7b are laminated, and is arranged on the tread portion 2 outside the carcass layer 6 in the tire radial direction, and covers the carcass layer 6 in the tire circumferential direction. It is. The belts 7a and 7b are formed by coating a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20 ° to 30 °) with respect to the tire circumferential direction with a coating rubber. The cord is made of, for example, steel or an organic fiber such as polyester, rayon, or nylon. Further, the overlapping belts 7a and 7b are arranged so that the cords of the belts cross each other.

  The belt reinforcing layer 8 is disposed outside the belt layer 7 in the tire radial direction, which is the outer periphery of the belt layer 7, and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is formed by coating a plurality of cords (not shown) substantially parallel to the tire circumferential direction and arranged in parallel in the tire width direction with a coat rubber. The cord is made of, for example, steel or an organic fiber such as polyester, rayon, or nylon, and the angle of the cord is within a range of ± 5 ° with respect to the tire circumferential direction. The belt reinforcing layer 8 shown in FIG. 1 is arranged so as to cover the end of the belt layer 7 in the tire width direction. The configuration of the belt reinforcing layer 8 is not limited to the above, and is not explicitly shown in the drawings. However, the configuration is such that the belt reinforcing layer 8 covers the entire belt layer 7 or has, for example, two reinforcing layers, The reinforcing layer is formed so as to be larger in the tire width direction than the belt layer 7 and disposed so as to cover the entire belt layer 7, and the reinforcing layer on the outer side in the tire radial direction is disposed so as to cover only the end portion of the belt layer 7 in the tire width direction. Or a configuration having, for example, two reinforcement layers, and each reinforcement layer is arranged so as to cover only the end in the tire width direction of the belt layer 7. That is, the belt reinforcing layer 8 overlaps at least the end in the tire width direction of the belt layer 7. Further, the belt reinforcing layer 8 is provided by winding a belt-like strip material having a width of, for example, about 10 mm in the tire circumferential direction.

  The internal structure of the pneumatic tire 1 described above shows a typical example of the pneumatic tire 1, but the internal structure is not limited to this.

  As shown in FIG. 2, the tread surface 10 of the tread portion 2 has a plurality of circumferential main grooves 30 extending in the tire circumferential direction. In the present embodiment, three circumferential main grooves 30 have a tire width. It is formed side by side in the direction. Of the three circumferential main grooves 30, two circumferential main grooves 30 disposed outermost in the tire width direction, that is, the three circumferential main grooves 30 are disposed at both ends in the tire width direction of the three circumferential main grooves 30. The two circumferential main grooves 30 provided are outermost main grooves 32. Further, among the three circumferential main grooves 30, the circumferential main groove 30 disposed between the two outermost main grooves 32 in the tire width direction is a center main groove 31. Of these, the center main groove 31 is located on the tire equatorial plane CL. Further, of the two outermost main grooves 32, the outermost main groove 32 disposed on one side of the center main groove 31 in the tire width direction is a first outermost main groove 33, and is provided in the tire width direction. The outermost main groove 32 disposed on the other side of the center main groove 31 is a second outermost main groove 34.

  In addition, the two outermost main grooves 32 are disposed on the inner side in the tire width direction with respect to the grounding ends T which are both outermost ends in the tire width direction of the grounding region. In FIG. 2, the grounding end T is shown continuously in the tire circumferential direction. The tread surface 10 of the tread portion 2 of the pneumatic tire 1 is dried when the pneumatic tire 1 is rim-assembled to a prescribed rim, filled with a prescribed internal pressure and subjected to 70% of a prescribed load. It is an area where it contacts with a flat road surface. The specified rim in this case is a "standard rim" specified by JATMA, a "Design Rim" specified by TRA, or a "Measuring Rim" specified by ETRTO. The specified internal pressure is the “maximum air pressure” specified by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or the “INFLATION PRESSURES” specified by ETRTO. The specified load is a “maximum load capacity” specified by JATMA, a maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “LOAD CAPACITY” specified by ETRTO.

  The circumferential main groove 30 refers to a vertical groove that at least partially extends in the tire circumferential direction. Generally, the circumferential main groove 30 has a groove width of 5.0 mm or more, a groove depth of 5.0 mm or more, and has a treadwear indicator (slip sign) indicating the end of wear inside. In the present embodiment, the circumferential main groove 30 has a groove width of not less than 5.0 mm and not more than 12.0 mm, has a groove depth of not less than 5.0 mm and not more than 9.0 mm, and has a tire equatorial plane (tire). (Equatorial line) CL is substantially parallel. The circumferential main groove 30 may extend linearly in the tire circumferential direction, or may be provided in a wavy or zigzag shape.

  Four rows of land portions 20 are defined on the tread surface 10 by the three circumferential main grooves 30. The four rows of land portions 20 are disposed outside the center main grooves 31 on both sides in the tire width direction and two rows of center land portions 21 and 22 and the two outermost main grooves 32 on the outer sides in the tire width direction. And two rows of shoulder land portions 23 and 24.

  The center land portion 21 and the shoulder land portion 23 disposed on both sides of the first outermost main groove 33 in the tire width direction extend in the tire circumferential direction, and have a groove width of the circumferential main groove 30. The circumferential narrow grooves 40 each having a narrower groove width are formed. Of the circumferential narrow grooves 40 formed in the center land portion 21 and the shoulder land portion 23, the circumferential narrow grooves formed in the center land portion 21 are disposed inside the first outermost main groove 33 in the tire width direction. The groove 40 is an inner circumferential narrow groove 41, and the circumferential thin groove 40 formed on the shoulder widthwise portion 23 and disposed outside the first outermost main groove 33 in the tire width direction is formed in the outer circumferential direction. It is a narrow groove 42.

  In the land portion 20 (the center land portion 21 or the shoulder land portion 23) in which the circumferential narrow groove 40 is formed, the circumferential width narrow distance W2 from the end of the ground contact area in the tire width direction is the circumferential narrow groove. The groove 40 is disposed within a range of 20% to 80% of the contact width W1 of the land portion 20 (the center land portion 21 or the shoulder land portion 23). The contact area of the land section 20 is an area where the tread surface 10 of the land section 20 contacts the ground under the same conditions as the above-mentioned conditions of the ground end T. For this reason, the ground contact width W1 of the center land portion 21 is determined by the distance between the edge (opening end) sandwiching the center land portion 21 between the center main groove 31 and the first outermost main groove 33 that define the center land portion 21. In the tire width direction. In addition, the contact width W1 of the shoulder land portion 23 is located on the shoulder land portion 23 side edge (opening end) of the first outermost main groove 33 that defines the shoulder land portion 23 and on the shoulder land portion 23. It is the distance in the tire width direction from the ground contact end T.

  Therefore, the distance W2 in the tire width direction from the edge of the center main groove 31 or the first outermost main groove 33 that defines the center land portion 21 is equal to the ground contact width W1 of the center land portion 21. Is provided at a position within the range of 20% or more and 80% or less. In addition, the outer circumferential narrow groove 42 is formed such that a distance W2 in the tire width direction from an edge of the first outermost main groove 33 that defines the shoulder land portion 23 or a ground contact end T located on the shoulder land portion 23 is a shoulder. It is arranged at a position within a range of 20% or more and 80% or less with respect to the contact width W1 of the land portion 23. The circumferential narrow groove 40 formed as described above has a groove width in the range of 1.5 mm to 4.5 mm and a groove depth in the range of 2.0 mm to 5.0 mm. ing.

  The shoulder land portion 23 disposed outside the first outermost main groove 33 in the tire width direction and the shoulder land portion 24 disposed outside the second outermost main groove 34 in the tire width direction are respectively provided. A plurality of lug grooves 50 extending in the tire width direction are provided. Of these, the first lug groove 51 which is the lug groove 50 formed in the shoulder land portion 23 in which the outer circumferential narrow groove 42 is formed has an inner end in the tire width direction communicating with the outer circumferential narrow groove 42. The end on the outer side in the tire width direction is open at the design end E beyond the ground end T. A second lug groove 52, which is a lug groove 50 formed on the other shoulder land portion 24, has an inner end in the tire width direction terminated in the shoulder land portion 24, and an outer end in the tire width direction is grounded. It is open at the design end E beyond the end T. These lug grooves 50 extend in the tire width direction and are inclined in the tire circumferential direction.

  The lug groove 50 formed as described above has a groove width in a range of 3.0 mm or more and 10.0 mm or less and a groove depth in a range of 4.0 mm or more and 8.0 mm or less. The design end E is located on the outer side in the tire width direction of the tread portion 2 and is the outermost end in the tire width direction of the tread surface 10 of the tread portion 2. Is the end. FIG. 2 shows the design end E continuously in the tire circumferential direction. That is, in the tread portion 2, on a dry flat road surface, a region closer to the design end E than the grounding end T is a region that is not normally grounded on the road surface.

  Further, a plurality of auxiliary grooves 60 are formed in the land portion 20. The auxiliary groove 60 is a groove having a groove width in a range of 0.4 mm to 1.2 mm and a groove depth in a range of 2.0 mm to 5.0 mm. The auxiliary grooves 60 include a first outermost main groove penetration auxiliary groove 61, a second outermost main groove penetration auxiliary groove 62, and a center auxiliary groove 63.

  The first outermost main groove penetration auxiliary groove 61 extends in the tire width direction while being inclined in the tire circumferential direction, and is an auxiliary groove 60 formed across the first outermost main groove 33. In other words, the first outermost main groove penetration auxiliary groove 61 is located at the center land portion from the position on the inner side in the tire width direction than the outer circumferential narrow groove 42 in the shoulder land portion 23 defined by the first outermost main groove 33. The first outermost main groove 33 is formed so as to extend to a position on the outside in the tire width direction of the inner circumferential narrow groove 41 in 21.

  The second outermost main groove penetration auxiliary groove 62 extends in the tire width direction while being inclined in the tire circumferential direction, and is an auxiliary groove 60 formed across the second outermost main groove 34. In detail, the second outermost main groove penetration auxiliary groove 62 is located on the center land located on the opposite side of the center main groove 31 from the center land portion 21 side where the inner circumferential narrow groove 41 is formed in the tire width direction. From the position of the tire width direction inner end in the portion 22 to the position near the second outermost main groove 34 in the shoulder land portion 24 adjacent to the center land portion 22 via the second outermost main groove 34, The second outermost main groove 34 is formed to penetrate. The second outermost main groove penetrating auxiliary groove 62 has a portion formed in the center land portion 22, and both ends thereof are formed in the center main groove 31 and the second outermost main groove 34 which define the center land portion 22. They communicate with each other and are bent in the circumferential direction of the tire in the center land portion 22. Further, a portion formed in the shoulder land portion 24 in the second outermost main groove penetration auxiliary groove 62 has one end communicating with the second outermost main groove 34 and the other end terminating in the shoulder land portion 24. .

  The center auxiliary groove 63 is inclined in the tire circumferential direction in the tire width direction in a region between the inner circumferential narrow groove 41 and the center main groove 31 in the center land portion 21 where the inner circumferential narrow groove 41 is formed. One end communicates with the center main groove 31, and the other end ends in the center land portion 21.

  Further, a plurality of sipes 65 are formed in the land portion 20. The sipe 65 here is formed in a narrow groove shape on the tread surface 10, and the pneumatic tire 1 is rim-assembled into a specified rim, and a wall surface which forms the narrow groove when there is no load under an internal pressure condition of a specified internal pressure. When they are not in contact with each other, but when the narrow groove is located in the portion of the grounding surface formed on the flat plate when loaded vertically on the flat plate, or when the land portion 20 where the narrow groove is formed falls down, It means that the wall surfaces constituting the narrow groove or at least a part of the portion provided on the wall surface come into contact with each other due to deformation of the land portion 20. The sipe 65 includes a first shoulder sipe 66 and a second shoulder sipe 67.

  The first shoulder sipe 66 is inclined in the tire width direction in a region outside the outer circumferential narrow groove 42 in the shoulder land portion 23 defined by the first outermost main groove 33 in the tire width direction while being inclined in the tire circumferential direction. And both ends are terminated in the shoulder land portion 23. The first shoulder sipes 66 formed on the shoulder land portion 23 are alternately arranged in the tire circumferential direction with the first lug grooves 51 also formed on the shoulder land portion 23.

  The second shoulder sipe 67 is formed in the shoulder land portion 24 defined by the second outermost main groove 34 so as to extend in the tire width direction while being inclined in the tire circumferential direction. Terminated with The second shoulder sipes 67 formed on the shoulder land portion 24 are alternately arranged in the tire circumferential direction with the second lug grooves 52 also formed on the shoulder land portion 24.

  FIG. 3 is a detailed view of a portion A in FIG. FIG. 4 is a perspective view showing the connecting portion 48 between the outer circumferential narrow groove 42 and the first lug groove 51 shown in FIG. FIG. 5 is a sectional view taken along line BB of FIG. FIG. 6 is a view taken in the direction of the arrows CC in FIG. FIG. 7 is a detailed view of a portion D in FIG. FIG. 8 is a cross-sectional view in the tire width direction of FIG.

  As shown in FIGS. 3 to 8, a portion where the circumferential narrow groove 40 and the lug groove 50 are connected is a connecting portion 48. In the present embodiment, the connection portion 48 is a portion where the opening end of the outer circumferential narrow groove 42 on the outer side in the tire width direction and the end of the first lug groove 51 on the inner side in the tire width direction are connected. The connecting portion 48 includes an intersecting portion 48A where the outer circumferential narrow groove 42 and the first lug groove 51 intersect, a lug groove side connecting portion 48B in the first lug groove 51, and a thinner portion in the outer circumferential narrow groove 42. And a groove side connecting portion 48C. In the plan view shown in FIG. 3, the crossing portion 48 </ b> A extends the first lug groove 51 from the inner end in the tire width direction to the inside in the tire width direction and crosses the portion that overlaps in the outer circumferential narrow groove 42. Say. The lug groove side connecting portion 48B refers to a portion connected to the crossing portion 48A in the first lug groove 51 in a plan view shown in FIG. The narrow groove side connecting portion 48C refers to a portion connected to the crossing portion 48A in the outer circumferential narrow groove 42 in the plan view shown in FIG. A bottom upper portion 70 is formed in such a connecting portion 48.

  The bottom top 70 has an intersection bottom top 71, a width bottom top 72, and a circumferential bottom top 73. The intersection bottom upper portion 71 is formed at the intersection 48A. The width direction bottom upper part 72 is formed in the lug groove side connection part 48 </ b> B in the first lug groove 51 and is connected to the cross bottom upper part 71. The circumferential bottom upper portion 73 is formed in the narrow groove side connecting portion 48 </ b> C in the outer circumferential narrow groove 42 and is connected to the cross bottom upper portion 71.

  The cross bottom upper portion 71 is formed in the outer circumferential narrow groove 42 and is raised from the groove bottom 42 a of the outer circumferential narrow groove 42 so as to protrude outward in the tire radial direction. The cross bottom upper portion 71 is formed integrally with a part of one groove wall 42b of the outer circumferential narrow groove 42. As shown in FIGS. 6 to 8, the cross bottom upper portion 71 has a top surface 71 a that is located farthest away from the groove bottom 42 a in the tire radial direction. The top surface 71a is a plane that is arranged in the intersection 48A and formed substantially parallel to the groove bottom 42a. Further, the intersection bottom upper portion 71 has an end face 71b facing one side in the tire circumferential direction in the outer circumferential narrow groove 42. The end surface 71b is a surface provided between the top surface 71a and the groove bottom 42a. In the present embodiment, the end surface 71b is inclined with respect to the groove depth direction of the outer circumferential narrow groove 42 so as to expand in the tire circumferential direction from the top surface 71a toward the groove bottom 42a. In the present embodiment, the end face 71b is provided so as to be inclined so as to deviate from the intersection 48A in the tire circumferential direction. Further, although not shown in the drawing, the end surface 71b may be formed as an upright wall surface provided along the tire radial direction from the top surface 71a toward the groove bottom 42a and arranged in the intersection 48A.

  The width direction bottom upper part 72 is formed in the first lug groove 51, and is raised from the groove bottom 51 a of the first lug groove 51 so as to protrude outward in the tire radial direction. The width direction bottom upper part 72 is formed integrally with a part of both groove walls 51 b of the first lug groove 51. The width direction bottom upper portion 72 is connected to the intersection bottom upper portion 71 on the outer side in the tire width direction of the intersection bottom upper portion 71. As shown in FIGS. 6 to 8, the width-direction bottom upper portion 72 has a top surface 72 a that is located farthest away from the groove bottom 51 a in the tire radial direction. The top surface 72a is arranged in the lug groove side connecting portion 48B and is a plane formed substantially parallel to the groove bottom 51a. In addition, the width-direction bottom upper portion 72 has an end face 72b facing outward in the tire width direction in the first lug groove 51. The end face 72b is a face provided between the top face 72a and the groove bottom 51a. In the present embodiment, the end surface 72b is inclined with respect to the groove depth direction of the first lug groove 51 so as to expand in the tire circumferential direction from the top surface 72a toward the groove bottom 51a. In the present embodiment, the end surface 72b is provided so as to be inclined so as to be displaced in the tire circumferential direction from the lug groove side connecting portion 48B. Although not explicitly shown in the drawing, the end surface 72b is formed along the tire radial direction from the top surface 72a toward the groove bottom 51a and formed as an upright wall surface arranged in the lug groove side connection portion 48B. Is also good.

  The circumferential bottom upper portion 73 is formed in the outer circumferential narrow groove 42, and is raised from the groove bottom 42 a of the outer circumferential narrow groove 42 so as to protrude outward in the tire radial direction. The circumferential bottom upper portion 73 is formed integrally with both groove walls 42 b of the outer circumferential narrow groove 42. The circumferential bottom upper portion 73 is connected to the cross bottom upper portion 71 on one side of the cross bottom upper portion 71 in the tire circumferential direction. Although not shown in the drawing, the circumferential bottom upper portion 73 may be connected to the cross bottom upper portion 71 both in the tire circumferential direction of the cross bottom upper portion 71. As shown in FIGS. 6 to 8, the circumferential bottom upper portion 73 has a top surface 73 a located farthest away from the groove bottom 42 a in the tire radial direction. The top surface 73a is arranged in the narrow groove side connecting portion 48C and is a plane formed substantially parallel to the groove bottom 42a. In addition, the circumferential bottom upper portion 73 has an end surface 73b facing the other in the tire circumferential direction (the opposite direction in which the end surface 71b of the cross bottom upper portion 71 faces) in the outer circumferential narrow groove 42. The end surface 73b is a surface provided between the top surface 73a and the groove bottom 42a. In the present embodiment, the end face 73b is inclined with respect to the groove depth direction of the outer circumferential narrow groove 42 so as to expand in the tire circumferential direction from the top face 73a toward the groove bottom 42a. In the present embodiment, the end surface 73b is provided to be inclined so as to be displaced in the tire circumferential direction from the narrow groove side connecting portion 48C. Although not explicitly shown in the drawing, the end surface 73b is formed as an upright wall surface provided along the tire radial direction from the top surface 73a toward the groove bottom 42a and arranged in the narrow groove side connecting portion 48C. Is also good.

  As shown in FIG. 8, the pneumatic tire 1 of the present embodiment has a bottom upper portion 70 formed in the connecting portion 48, as shown in FIG. The height Hr of the cross bottom upper portion 71, the height Ha of the width bottom upper portion 72 from the groove bottom 42a (the position where the groove bottom 42a is extended in the tire width direction) to the top surface 72a, and the groove bottom 42a And the height Hb of the circumferential bottom upper portion 73 from the top surface 73a to the top surface 73a.

  Specifically, the height Ha of the width direction bottom upper portion 72 and the height Hr of the intersection bottom upper portion 71 satisfy the relationship of Ha <Hr, and the height Hb of the circumferential bottom upper portion 73 and the height of the intersection bottom upper portion 71 are satisfied. Hr satisfies the relationship of Hb <Hr.

  When the pneumatic tire 1 according to the present embodiment is mounted on a vehicle, the pneumatic tire 1 is assembled to the rim wheel by fitting the rim wheel to the bead portion 5, and the inside is filled with air. Attach it to the vehicle in the freighted state. When the vehicle travels, the pneumatic tire 1 rotates while a portion of the tread surface 10 located below the tread surface 10 contacts the road surface. The vehicle travels by transmitting a driving force or a braking force to the road surface or generating a turning force by a frictional force between the tread surface 10 and the road surface.

  For example, when the vehicle equipped with the pneumatic tire 1 travels on a dry road surface, the driving force or the braking force is transmitted to the road surface mainly by the frictional force between the tread surface 10 and the road surface, and the turning force is used. It travels by generating or. Also, when traveling on a wet road surface, water between the tread surface 10 and the road surface enters the circumferential main groove 30, the lug groove 50, and the like, and the water between the tread surface 10 and the road surface is formed by these grooves. Run while draining water. As a result, the tread surface 10 easily comes into contact with the road surface, and the vehicle can travel as desired by the frictional force between the tread surface 10 and the road surface.

  Further, when traveling on a snowy road surface, the pneumatic tire 1 compresses the snow on the road surface with the tread surface 10, and the snow on the road surface enters the circumferential main groove 30 and the lug groove 50, so that the snow is removed. Is also compacted in the groove. In this state, the shearing force acts on snow in the groove when a driving force or a braking force acts on the pneumatic tire 1 or a force in the tire width direction acts upon turning of the vehicle. A so-called snow column shear force is generated, and a resistance is generated between the pneumatic tire 1 and the road surface due to the snow column shear force, so that the driving force and the braking force can be transmitted to the snow-covered road surface, and the vehicle is driven on the snow. Running on the road surface becomes possible.

  When traveling on a snowy road surface, the vehicle travels using the edge effect of the circumferential main groove 30, the lug groove 50, the auxiliary groove 60, and the sipe 65. That is, when the vehicle travels on a snowy road surface, the vehicle travels using the resistance caused by the edges of the circumferential main groove 30 and the lug groove 50 and the edges of the auxiliary groove 60 and the sipe 65 being caught on the snow surface. Thereby, the resistance between the tread surface 10 and the road surface on snow increases due to the frictional force and the edge effect, and the running performance of the vehicle equipped with the pneumatic tire 1 can be ensured. Furthermore, since the circumferential narrow groove 40 other than the circumferential main groove 30 is formed on the tread surface 10 as a groove extending in the tire circumferential direction, the edge effect can be further enhanced. This makes it possible to more reliably improve snow performance, which is steering stability when traveling on a snowy road surface.

  On the other hand, the connecting portion 48 between the first lug groove 51, which is the lug groove 50, and the outer circumferential narrow groove 42, which is the circumferential narrow groove 40, has a bottom upper portion 70, so that the outer circumferential narrow groove is formed. A decrease in rigidity of the land portion 20 due to the formation of 42 can be suppressed by the bottom upper portion 70. That is, the bottom upper part 70 is formed in the width direction bottom upper part 72 formed in the first lug groove 51, the circumferential bottom upper part 73 formed in the outer circumferential narrow groove 42, the first lug groove 51 and the outer circumferential part. The first lug groove 51 and the outer circumferential narrow groove 42 have a cross bottom upper portion 72 and a circumferential bottom upper portion 71 that are connected to each other at a crossing portion 48 </ b> A with the direction narrow groove 42. The rigidity of the land portion 20 near the connecting portion 48 can be secured. Accordingly, it is possible to suppress a decrease in dry performance, which is steering stability when traveling on a dry road surface, due to a decrease in rigidity of the land portion 20. Therefore, the dry performance is improved by securing the rigidity of the shoulder land portion 23 in which the outer circumferential narrow groove 42 is formed by the bottom upper portion 70 while ensuring the snow performance by forming the outer circumferential narrow groove 42. Can be done.

  Further, the bottom upper portion 70 has an intersection bottom upper portion 71 formed at a crossing portion 48A where the outer circumferential narrow groove 42 and the first lug groove 51 intersect. The cross bottom upper portion 71 is formed such that the height Hr with respect to the groove bottom 42a of the outer circumferential narrow groove 42 is higher than the height Ha of the width bottom upper portion 72 and the height Hb of the circumferential bottom upper portion 73. ing. For this reason, the rigidity of the land portion 20 by forming the outer circumferential narrow groove 42 in the connecting portion 48 between the first lug groove 51 which is the lug groove 50 and the outer circumferential narrow groove 42 which is the circumferential narrow groove 40. Can be further suppressed. As a result, it is possible to improve dry performance while ensuring snow performance.

  Further, since the outer circumferential narrow groove 42, which is the circumferential narrow groove 40 in which the circumferential bottom upper portion 73 is formed, is disposed outside the outermost main groove 32 in the tire width direction, the snow performance is more reliably ensured. While improving the dry performance. In other words, the shoulder land portion 23 disposed on the outer side of the outermost main groove 32 in the tire width direction easily comes into contact with a large load at the time of turning of the vehicle, and becomes more important in securing the steering stability during turning. However, in the present embodiment, the outer circumferential narrow groove 42 is formed as the circumferential narrow groove 40 in the shoulder land portion 23. For this reason, the edge effect in the shoulder land portion 23 that is likely to be in contact with a large load during turning of the vehicle can be enhanced, and snow performance can be more reliably ensured. In addition, the rigidity of the shoulder land portion 23 can be ensured because the bottom upper portion 70 is formed at the connecting portion 48 between the outer circumferential narrow groove 42 formed on the shoulder land portion 23 and the first lug groove 51. Thus, dry performance can be ensured more reliably. As a result, the dry performance can be improved while ensuring the snow performance more reliably.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 8, the height Ha of the width direction bottom upper portion 72 and the height Hr of the cross bottom upper portion 71 are (1.75 × Ha) ≦ Hr. It is preferable to satisfy the relationship of ≦ (2.25 × Ha).

  According to the pneumatic tire 1, by setting (1.75 × Ha) ≦ Hr, the rigidity of the shoulder land portion 23 can be sufficiently secured, and the dry performance can be surely improved. On the other hand, by setting Hr ≦ (2.25 × Ha), excessive rigidity of the shoulder land portion 23 can be suppressed, and snow performance can be ensured.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 8, the height Hb of the circumferential bottom upper portion 73 and the height Hr of the cross bottom upper portion 71 are (1.75 × Hb) ≦ Hr. It is preferable to satisfy the relationship of ≦ (2.25 × Hb).

  According to the pneumatic tire 1, by setting (1.75 × Hb) ≦ Hr, the rigidity of the shoulder land portion 23 can be sufficiently secured, and the dry performance can be surely improved. On the other hand, by setting Hr ≦ (2.25 × Hb), excessive rigidity of the shoulder land portion 23 can be suppressed, and snow performance can be ensured.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 7, the groove width Wg1 of the first lug groove 51 and the top surface 72a of the width direction bottom upper portion 72 excluding the inclined end surface 72b in the tire width direction. It is preferable that the length La satisfies a relationship of (0.5 × Wg1) ≦ La ≦ (1.5 × Wg1).

  According to the pneumatic tire 1, by setting (0.5 × Wg1) ≦ La, the rigidity of the shoulder land portion 23 can be sufficiently secured, and the dry performance can be more reliably improved. On the other hand, by setting La ≦ (1.5 × Wg1), drainage can be ensured, and wet performance, which is steering stability when traveling on a wet road surface, can be ensured.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 7, the groove width Wg2 of the outer circumferential narrow groove 42 and the tire circumferential direction of the top surface 73a excluding the inclined end surface 73b of the circumferential bottom upper portion 73. It is preferable that the length Lb satisfies the relationship of (0.5 × Wg2) ≦ Lb ≦ (1.5 × Wg2).

  According to the pneumatic tire 1, when (0.5 × Wg2) ≦ Lb, the rigidity of the shoulder land portion 23 can be sufficiently secured, and the dry performance can be more reliably improved. On the other hand, by satisfying Lb ≦ (1.5 × Wg2), drainage can be ensured, and wet performance can be ensured.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 8, the groove depth Dg <b> 1 of the outer circumferential narrow groove 42 (the depth of the intersection 48 </ b> A) and the height Ha of the width direction bottom upper portion 72 are determined. Preferably satisfies the relationship of (0.15 × Dg1) ≦ Ha ≦ (0.35 × Dg1).

  According to the pneumatic tire 1, by setting (0.15 × Dg1) ≦ Ha, the rigidity of the shoulder land portion 23 can be sufficiently secured, and the dry performance can be more reliably improved. On the other hand, by setting Ha ≦ (0.35 × Dg1), drainage can be ensured, and wet performance can be ensured.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 8, the groove depth Dg1 of the outer circumferential narrow groove 42 (the depth of the intersection 48A) and the height Hb of the circumferential bottom upper portion 73 are determined. Preferably satisfies the relationship of (0.15 × Dg1) ≦ Hb ≦ (0.35 × Dg1).

  According to the pneumatic tire 1, by setting (0.15 × Dg1) ≦ Hb, the rigidity of the shoulder land portion 23 can be sufficiently secured, and the dry performance can be more reliably improved. On the other hand, when Hb ≦ (0.35 × Dg1), drainage can be ensured, and wet performance can be ensured.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 8, the height Ha of the width direction bottom upper portion 72 and the height Hb of the circumferential direction bottom upper portion 73 are 0.75 ≦ Ha / Hb ≦. It is preferable to satisfy the relationship of 1.25.

  In the pneumatic tire 1, the rigidity of the shoulder land portion 23 is sufficiently ensured by setting the difference between the height Ha of the widthwise bottom upper portion 72 and the height Hb of the circumferential bottom upper portion 73 within a specified range. And dry performance can be more reliably improved.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 8, the height Hr of the cross bottom upper portion 71, the height Ha of the width bottom upper portion 72, and the height Hb of the circumferential bottom upper portion 73. Preferably satisfies the relationship of [1.75 × {(Ha + Hb) / 2}] ≦ Hr ≦ [2.25 × {(Ha + Hb) / 2}].

  According to the pneumatic tire 1, by setting [1.75 × {(Ha + Hb) / 2}] ≦ Hr, the rigidity of the shoulder land portion 23 can be sufficiently secured, and the dry performance can be reliably improved. can do. On the other hand, by setting Hr ≦ [2.25 × {(Ha + Hb) / 2}], excessive rigidity of the shoulder land portion 23 can be suppressed, and snow performance can be ensured.

[Modification]
In the embodiment described above, the bottom upper portion 70 is formed at the connection portion 48 between the outer circumferential narrow groove 42 and the first lug groove 51, but the bottom upper portion 70 is formed at another connection portion 48. You may. That is, the cross bottom upper portion 71 of the bottom upper portion 70 may be formed at the intersection of the outer circumferential narrow groove 42 and the circumferential narrow groove 40 other than the first lug groove 51 and the lug groove 50, and may be formed in the width direction. The bottom upper part 72 may be formed in the lug groove 50 other than the first lug groove 51, and the circumferential bottom upper part 73 may be formed in the circumferential thin groove 40 other than the outer circumferential thin groove 42. .

  In the embodiment described above, three circumferential main grooves 30 are formed, and the circumferential narrow grooves 40 are formed on both sides of the first outermost main groove 33 in the tire width direction. Other than that. The tread pattern formed on the tread surface 10 is not limited to the pattern in the above-described embodiment.

  In this embodiment, snow performance (steering stability, which is steering stability when traveling on a snowy road surface) and dry performance (steering stability when traveling on a dry road surface) are used for a plurality of types of pneumatic tires having different conditions. (See FIG. 9 and FIG. 10).

  In the performance evaluation test, the pneumatic tire 1 with a tire size of 185 / 65R15 specified by JATMA is rim assembled to a JATMA standard rim wheel of rim size 15 × 6J and mounted on a front wheel drive vehicle, and the air pressure is reduced. The test was performed by adjusting the front wheel to 220 kPa and the rear wheel to 210 kPa, and performing a test run with one passenger.

  The snow performance was evaluated by comparing the steering stability of the test vehicle on a test course on a snowy road surface by sensory evaluation of a test driver. The snow performance is evaluated by expressing the sensory evaluation of the test driver as an index with the conventional example described later as 100, and the larger the index is, the higher the steering stability when traveling on a snowy road surface and the more excellent the snow performance is. Is shown. In the evaluation of the snow performance of this embodiment, an index of 95 or more indicates that the snow performance is secured.

  The dry performance was evaluated by performing a braking test on a test course on a dry road surface using the test vehicle, and expressing the reciprocal of the braking distance by an index with a conventional example described below being 100. The larger the value, the shorter the braking distance and the better the dry performance. In the evaluation of the dry performance of this embodiment, an index of 109 or more indicates that the dry performance is improved.

  In FIG. 9, the conventional pneumatic tire has a circumferential narrow groove 40 but does not have a bottom upper part 70 with respect to the pneumatic tire 1 shown in FIGS. 1 and 2. The pneumatic tire of Comparative Example 1 has the circumferential narrow groove 40 but does not have the circumferential bottom upper portion 73 and the cross bottom upper portion 71 in the bottom upper portion 70. The pneumatic tire of Comparative Example 2 has the circumferential narrow groove 40 but does not have the width-direction bottom upper portion 72 and the cross bottom upper portion 71 in the bottom portion 70. The pneumatic tire of Comparative Example 3 has the circumferential narrow groove 40 but does not have the cross bottom upper portion 71 at the bottom upper portion 70.

  On the other hand, in FIGS. 9 and 10, the pneumatic tires of Examples 1 to 24 have a circumferential narrow groove 40 and a bottom upper part 70 like the pneumatic tires shown in FIGS. 1, 2 and 6. The bottom upper part 70 has a width direction bottom upper part 72, a circumferential direction bottom upper part 73, and a cross bottom upper part 71. Based on the groove bottom of the circumferential narrow groove 40, the height Ha of the width direction bottom upper part 72 is The height Hr of the cross bottom upper portion 71 satisfies the relationship of Ha <Hr, and the height Hb of the circumferential bottom upper portion 73 and the height Hr of the cross bottom upper portion 71 satisfy the relationship of Hb <Hr.

  As shown in the test results of FIGS. 9 and 10, it can be seen that the pneumatic tires of Examples 1 to 24 have improved dry performance while ensuring snow performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Shoulder part 4 Side wall part 5 Bead part 6 Carcass layer 7 Belt layer 7a, 7b Belt 8 Belt reinforcement layer 10 Tread surface 15 Bead core 16 Bead filler 20 Land part 21, 22 Center land part 23, 24 shoulder land portion 30 circumferential main groove 31 center main groove 32 outermost main groove 33 first outermost main groove 34 second outermost main groove 40 circumferential narrow groove 41 inner circumferential narrow groove 42 outer circumferential narrow groove 42a Groove bottom 42b Groove wall 48 Connecting portion 48A Intersection 48B Lug groove side connecting portion 48C Narrow groove side connecting portion 50 Lug groove 51 First lug groove 51a Groove bottom 51b Groove wall 52 Second lug groove 60 Auxiliary groove 61 First outermost Main groove penetration auxiliary groove 62 Second outermost main groove penetration auxiliary groove 63 Center auxiliary groove 65 Sipe 66 First shoulder sipe 67 Second shoulder -Sipe 70 Bottom top 71 Cross bottom top 71a Top face 71b End face 72 Width bottom top 72a Top face 72b End face 73 Circumferential bottom top 73a Top face 73b End face CL Tire equatorial plane E Design end T Ground end W1 Ground width W2 Distance Wg1 lag Groove width of the groove Wg2 Groove width of the circumferential narrow groove Dg1 Groove depth of the circumferential narrow groove Ha Height of the bottom top in the width direction Hb Height of the top of the circumferential bottom Hr Height of the top of the intersection bottom

Claims (9)

A circumferential narrow groove formed on the tread surface and extending in the tire circumferential direction,
A lug groove formed on the tread surface and extending in the tire width direction and communicating with the circumferential narrow groove,
An intersection bottom upper portion formed at an intersection where the circumferential direction narrow groove and the lug groove intersect,
A width-direction bottom upper portion provided in the lug groove and connected to the intersection bottom upper portion,
A circumferential bottom upper portion provided in the circumferential narrow groove and connected to the cross bottom upper portion;
With
The height Ha of the upper part in the width direction and the height Hr of the upper part of the intersection bottom satisfy a relationship of Ha <Hr, and the height Hb of the upper part in the circumferential direction, with reference to the groove bottom of the circumferential narrow groove. And the height Hr of the upper part of the intersection bottom satisfies the relationship of Hb <Hr.   2. The air according to claim 1, wherein a height Ha of the upper portion in the width direction and a height Hr of the upper portion of the intersection bottom satisfy a relationship of (1.75 × Ha) ≦ Hr ≦ (2.25 × Ha). 3. Containing tires.   The height Hb of the upper part in the circumferential direction and the height Hr of the upper part of the intersection bottom satisfy a relationship of (1.75 × Hb) ≦ Hr ≦ (2.25 × Hb). Pneumatic tires.   The groove width Wg1 of the lug groove and the length La in the tire width direction of the upper part in the width direction bottom satisfy a relationship of (0.5 × Wg1) ≦ La ≦ (1.5 × Wg1). 3. The pneumatic tire according to any one of 3.   The groove width Wg2 of the circumferential narrow groove and the length Lb of the circumferential bottom upper portion in the tire circumferential direction satisfy a relationship of (0.5 × Wg2) ≦ Lb ≦ (1.5 × Wg2). The pneumatic tire according to any one of claims 1 to 4.   The groove depth Dg1 of the circumferential narrow groove and the height Ha of the upper part in the width direction satisfy a relationship of (0.15 × Dg1) ≦ Ha ≦ (0.35 × Dg1). The pneumatic tire according to any one of the above.   The groove depth Dg1 of the circumferential narrow groove and the height Hb of the circumferential bottom upper portion satisfy the relationship of (0.15 × Dg1) ≦ Hb ≦ (0.35 × Dg1). The pneumatic tire according to any one of the above.   The height Ha of the top in the width direction and the height Hb of the top in the circumferential direction satisfy a relationship of 0.75 ≦ Ha / Hb ≦ 1.25. Pneumatic tires.   The height Hr of the upper portion of the intersection bottom, the height Ha of the upper portion of the width direction, and the height Hb of the upper portion of the circumferential direction are [1.75 × {(Ha + Hb) / 2}] ≦ Hr ≦ [ The pneumatic tire according to any one of claims 1 to 8, which satisfies a relationship of 2.25 x {(Ha + Hb) / 2}].

Images