JP2018043553A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire improving on-snow turning performance without damaging the steering stability performance on a dry road surface.SOLUTION: A pneumatic tire has on a shoulder rib 23B, plural shoulder lugs 11 extending along a tire width direction, ending in the shoulder rib without communicating with a shoulder main groove 22B and provided plurally in a tire circumferential direction, and plural shoulder circumferential narrow grooves 12 extending along the tire circumferential direction and having both ends ending in the shoulder rib including one end 12a provided separating within 5 mm from the end edge 11a of the shoulder lug groove. Further, the tire has on the inner rib 23A adjacent to the inside of the shoulder rib in the tire width direction, the inside lug grooves 31 extending along the tire width direction, including one end communicating with the shoulder main groove 22B and the other end ending in the inside rib and provided plurally in the tire circumferential direction, and the inside circumferential narrow grooves 32 extending along the tire circumferential direction, including both ends ending in the inside rib and including one end 32a provided separating within 5 mm from the end edge 31a of the inside lug groove.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  Conventionally, for example, the pneumatic tire described in Patent Document 1 aims to achieve both wear resistance performance and ride comfort performance. In this pneumatic tire, a pair of shoulder main grooves and a center main groove are provided in the tread portion, so that a pair of middle land portions and a pair of shoulder land portions are provided. The middle land portion is provided with a plurality of middle sipes, middle lag grooves, and middle longitudinal grooves. The middle vertical groove terminates in the middle land without communicating with the middle sipes and middle lug grooves. A plurality of shoulder lug grooves and shoulder longitudinal grooves are provided in the shoulder land portion. The shoulder longitudinal groove terminates in the shoulder land portion without communicating with the shoulder lug groove.

  Further, for example, the pneumatic tire described in Patent Document 2 aims to maintain high wear resistance even under tire width direction input conditions and to be excellent in braking performance on a wet road surface. In this pneumatic tire, a first main groove extending in the tire circumferential direction is provided on the tire equatorial plane of the tread, and second main grooves are provided at predetermined intervals on both sides thereof, and are partitioned by these. There are a center rib and a shoulder rib extending continuously in the tire circumferential direction. The center rib includes a width direction sipe that extends in the tire width direction and becomes a dead end in the center rib, and the shoulder rib includes a width direction sipe that extends in the tire width direction and becomes a dead end in the shoulder rib.

Japanese Patent Laying-Open No. 2015-071373 JP 2006-347346 A

  In the invention described in Patent Document 1, by providing a vertical groove that terminates in the land portion without communicating with the sipe and the lug groove, uneven wear near the end of the vertical groove is suppressed, and the land portion It is shown that excellent ride comfort performance is exhibited while maintaining wear resistance performance in order to relax the rigidity in the tire axial direction of the land portion while maintaining the rigidity in the tire circumferential direction. However, in the invention described in Patent Document 1, since the land portion is divided in the tire circumferential direction by sipe or the like, the rigidity of the land portion is lowered and the steering stability performance on the dry road surface is lowered.

  In the invention described in Patent Document 2, since the rib is not divided in the tire circumferential direction and no pseudo block is formed in the rib, the rigidity of the rib is maintained high, and even if the rib receives lateral input, the end of the rib is maintained. It is shown that uneven wear is less likely to occur in the part, and high wear resistance performance is maintained. Furthermore, in the invention described in Patent Document 2, the drainage performance on the wet road surface is improved by providing the lug groove or the width direction sipe, and the brake performance on the wet road surface is achieved by the drainage performance and edge effect of the lug groove or the width direction sipe. It has been shown to be excellent. However, in the invention described in Patent Document 2, since the width-direction sipe mainly extends in the width direction, it does not satisfy the skid resistance and it is difficult to improve the turning performance on snow.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve the turning performance on snow, without impairing the steering stability performance on a dry road surface.

  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 main groove that extends along the tire circumferential direction and is aligned in the tire width direction at the tread portion. A plurality of ribs formed in the tire width direction by the main grooves and continuously extending along the tire circumferential direction, and a shoulder rib on the outer side in the tire width direction of the main groove on the outermost side in the tire width direction. A plurality of shoulder lug grooves extending in the tire circumferential direction and extending in the tire width direction and terminating in the shoulder rib without communicating with the outermost main groove in the tire width direction; A shoulder circumferential narrow groove extending along the both ends and terminating in the shoulder rib and having one end portion spaced within 5 mm from the end of the shoulder lug groove, The inner rib adjacent to the inner side of the shoulder rib in the tire width direction extends along the tire width direction, one end communicates with the main groove on the outermost side in the tire width direction, and the other end terminates in the inner rib. A plurality of inner lug grooves provided in the direction, both ends extending in the tire circumferential direction and terminating in the inner rib, and one end portion is provided within 5 mm away from the end of the inner lug groove An inner circumferential narrow groove.

  According to this pneumatic tire, each lug groove and each circumferential narrow groove terminate in each rib, so that the land portion is not divided into blocks and is continuously formed along the tire circumferential direction. Therefore, the steering stability performance on the dry road surface can be maintained without causing a reduction in the rigidity of the ribs. In addition, by having each circumferential narrow groove, the edge component in the direction intersecting the tire circumferential direction can be compensated to improve the turning performance on snow (snow traction performance) when the chain is attached. In particular, since one end of each circumferential narrow groove is provided within 5 mm away from the end of the lug groove, one end of the circumferential narrow groove and the lug groove are suppressed while suppressing a decrease in rigidity. By imparting flexibility to the rib in the vicinity of the end of the groove, the edge effect of the circumferential narrow groove and the lug groove can be improved, and the turning performance on the snow (snow traction performance) when the chain is attached can be improved. As a result, it is possible to improve the turning performance on snow without impairing the steering stability performance on the dry road surface.

  In the pneumatic tire according to one aspect of the present invention, the shoulder rib and the inner rib are respectively provided on the tire equator plane, and on the outer side in the tire width direction from the tire equator plane, the tire rib direction view The shoulder circumferential narrow groove and the inner circumferential narrow groove are preferably continuous in the tire circumferential direction.

  According to this pneumatic tire, on one side outside the tire equatorial plane from the tire equatorial plane, the shoulder circumferential narrow groove overlaps with the inner circumferential narrow groove as viewed in the tire width direction, and the shoulder circumferential narrow groove as viewed in the tire width direction. And at least one of the inner circumferential narrow grooves is necessarily present. For this reason, an edge component that intersects the tire circumferential direction can always be applied by the shoulder circumferential narrow groove and the inner circumferential narrow groove in the tire circumferential direction, and the turning performance on the snow (snow traction performance) is improved when the chain is mounted. The effect can be obtained remarkably.

  In the pneumatic tire according to an aspect of the present invention, the shoulder circumferential narrow groove and the inner circumferential narrow groove may be disposed to be inclined at an angle of 5 degrees or more and 15 degrees or less with respect to the tire circumferential direction. preferable.

  According to this pneumatic tire, when the angle is less than 5 degrees and the shoulder circumferential narrow groove and the inner circumferential narrow groove are substantially parallel to the main groove, the ribs collapse together with the main groove with respect to the input in the tire width direction. Therefore, the rigidity of the rib tends to decrease. On the other hand, if the angle exceeds 15 degrees, the effect of compensating for the edge component tends to decrease. Therefore, in order to improve the turning performance on snow without impairing the steering stability performance on the dry road surface, the angle is preferably set to 5 degrees or more and 15 degrees or less with respect to the tire circumferential direction.

  In the pneumatic tire according to one aspect of the present invention, the shoulder rib and the inner rib are respectively provided with a tire equator plane as a boundary, and the shoulder circumferential narrow groove is disposed on the outer side in the tire width direction from the tire equator plane. And the inner circumferential narrow groove are preferably arranged to be inclined in different directions.

  According to this pneumatic tire, since the shoulder circumferential narrow groove and the inner circumferential narrow groove are arranged to be inclined in the opposite direction of the tire width direction with respect to the tire circumferential direction, input from various directions is possible. As a result, the edge component can be applied, and the effect of improving the turning performance on snow (snow traction performance) when the chain is attached can be significantly obtained.

  In the pneumatic tire according to an aspect of the present invention, the shoulder circumferential narrow groove and the inner circumferential narrow groove have a groove width of 0.4 mm or more and 2.0 mm or less, and more than the shoulder lug groove and the inner lug groove. However, it is preferable that the groove width is narrow.

  According to this pneumatic tire, by defining the groove width of the shoulder circumferential narrow groove and the inner circumferential narrow groove as described above, it is a groove width that is not too wide that can suppress a decrease in rigidity of the rib, It is possible to set the groove width within a range that is not so narrow that clogging due to snow hardly occurs.

  In the pneumatic tire according to one aspect of the present invention, the shoulder rib and the inner rib are respectively provided with a tire equator plane as a boundary, and on the outer side in the tire width direction from the tire equator plane, It is preferable that the inner lug grooves are arranged to be inclined in different directions.

  According to this pneumatic tire, the shoulder lug groove and the inner lug groove are arranged to be inclined in the opposite direction of the tire circumferential direction with respect to the tire width direction, so that the edge with respect to input from various directions Ingredients can be applied, and the effect of improving the turning performance on the snow (snow traction performance) when the chain is attached can be remarkably obtained.

  The pneumatic tire according to the present invention can improve the turning performance on snow without impairing the steering stability performance on the dry road surface.

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 the pneumatic tire according to the embodiment of the present invention. FIG. 3 is a plan view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 4 is an enlarged plan view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 5 is a plan view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 6 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. FIG. 7 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

  The pneumatic tire according to this embodiment will be described. FIG. 1 is a meridional sectional view of a pneumatic tire according to this embodiment. FIG. 2 is a plan view of the pneumatic tire according to the present embodiment. FIG. 3 is a plan view of another example of the pneumatic tire according to the present embodiment. FIG. 4 is an enlarged plan view of another example of the pneumatic tire according to the present embodiment. FIG. 5 is a plan view of another example of the pneumatic tire according to the present embodiment.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line.

  As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both sides thereof, and a sidewall portion 4 and a bead portion 5 that are sequentially continuous from the shoulder portions 3. ing. The pneumatic tire 1 includes a carcass layer 6 and a belt layer 7.

  The tread portion 2 is made of a rubber material (tread rubber), is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread surface 21 extends along the tire circumferential direction, and a plurality of main grooves 22 (three in this embodiment) are provided in the tire width direction. The tread surface 21 extends along the tire circumferential direction by the plurality of main grooves 22, and a plurality of rib-like land portions 23 (four in this embodiment) parallel to the tire equator line CL are formed. .

  In the present embodiment, the outermost main groove 22 in the tire width direction is referred to as a shoulder main groove 22B, and the main grooves 22 other than the shoulder main groove 22B are referred to as inner main grooves 22A. Further, the rib-shaped land portion 23 on the outer side in the tire width direction of the shoulder main groove 22B is referred to as a shoulder rib 23B, and the rib-shaped land portion 23 sandwiched between the inner main groove 22A and the shoulder main groove 22B is referred to as an inner rib 23A. The main groove 22 has a groove width of 3 mm to 20 mm and a groove depth of 5 mm to 10 mm.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. Further, the sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire 1. The bead unit 5 includes a bead core 51 and a bead filler 52. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 52 is a rubber material disposed in a space formed by folding the end portion in the tire width direction of the carcass layer 6 at the position of the bead core 51.

  The carcass layer 6 is configured such that each tire width direction end portion is folded back from the tire width direction inner side to the tire width direction outer side by a pair of bead cores 51 and is wound around in a toroidal shape in the tire circumferential direction. It is. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged in parallel at an angle in the tire circumferential direction with an angle with respect to the tire circumferential direction being along the tire meridian direction. The carcass cord is made of organic fibers (polyester, rayon, nylon, etc.). The carcass layer 6 is provided as at least one layer.

  The belt layer 7 has a multilayer structure in which at least two belts 7A and 7B are laminated, and is disposed on the tire radial direction outer side of the carcass layer 6 in the tread portion 2 and covers the carcass layer 6 in the tire circumferential direction. It is. The belts 7A and 7B are made by coating a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20 degrees to 30 degrees) with a coat rubber with respect to the tire circumferential direction. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). Further, the overlapping belts 7A and 7B are arranged so that the cords intersect each other.

  Although not clearly shown in the drawing, a belt reinforcing layer may be provided on the outer side of the belt layer 7 in the tire radial direction. The belt reinforcing layer covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer is coated with a coat rubber on a plurality of cords (not shown) arranged substantially parallel to the tire circumferential direction (± 5 degrees) in the tire width direction. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). The belt reinforcing layer is provided by winding a strip-shaped strip material (for example, a width of 10 [mm]) in the tire circumferential direction. The belt reinforcing layer is, for example, disposed so as to cover only the end portion in the tire width direction of the belt layer 7, or disposed so as to cover the entire belt layer 7, or has two layers of reinforcing layers. The reinforcing layer on the inner side in the radial direction is formed so as to be larger in the tire width direction than the belt layer 7 and covers the entire belt layer 7, and the reinforcing layer on the outer side in the tire radial direction covers only the end in the tire width direction of the belt layer 7. Or two reinforcing layers, and each reinforcing layer is arranged so as to cover only the end portion of the belt layer 7 in the tire width direction.

  In the pneumatic tire 1 of the present embodiment, the shoulder lug groove 11, the shoulder circumferential narrow groove 12, and the shoulder sipe 13 are provided on the tread surface 21 of the shoulder rib 23B. There are no other grooves in the shoulder rib 23B.

  The shoulder lug groove 11 is provided extending along the tire width direction so as to intersect the tire circumferential direction. The shoulder lug grooves 11 terminate in the shoulder ribs 23B without communicating with the outermost shoulder main grooves 22B in the tire width direction, and are provided in a plurality in the tire circumferential direction. The shoulder lug groove 11 is formed narrower than the main groove 22 in a range where the groove width is 1.5 mm or more and 6.5 mm or less. The shoulder lug groove 11 is formed shallower than the main groove 22 in a groove depth range of 4.0 mm or more and 9.0 mm or less.

  Further, the shoulder lug groove 11 is provided so as to intersect with the ground contact end T. The ground contact end T refers to both outermost ends in the tire width direction of the ground contact region, and in FIG. 2, the ground contact end T is shown continuously in the tire circumferential direction. The ground contact area is a flat surface in which the tread surface 21 of the tread portion 2 of the pneumatic tire 1 is dried when the pneumatic tire 1 is assembled on a regular rim and filled with a regular internal pressure and 70% of the regular load is applied. This is an area where it touches the ground. The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load is “maximum load capacity” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

  Further, the shoulder lug groove 11 is provided to be inclined at an inclination angle in the range of 2 degrees to 15 degrees with respect to the tire width direction. Note that the shoulder lug groove 11 may be formed to be curved in the extending direction, though not explicitly shown in the drawing. In this case, the inclination angle is an angle formed by the center line passing through the center of the width of the shoulder lug groove 11 and the base line in the tire width direction at each end of the shoulder lug groove 11.

  The shoulder circumferential direction narrow groove 12 is provided extending along the tire circumferential direction. Both ends of the shoulder circumferential narrow groove 12 terminate in the shoulder rib 23 </ b> B, and are provided apart from the shoulder lug groove 11 and the shoulder sipe 13. The shoulder circumferential narrow groove 12 is formed to be narrower than the shoulder lug groove 11 and wider than the shoulder sipe 13 within a groove width range of 0.4 mm to 2.0 mm. Further, the shoulder circumferential narrow groove 12 is formed shallower than the shoulder lug groove 11 and the shoulder sipe 13 within a groove depth range of 1.0 mm to 7.0 mm.

  In addition, the shoulder circumferential direction narrow groove 12 has a terminal end 12a at one end 12a near the shoulder main groove 22B in one shoulder lug groove 11 with respect to two shoulder lug grooves 11 adjacent in the tire circumferential direction. The other shoulder lug groove 11 is provided closer to the terminal 11a near the shoulder main groove 22B than the terminal end 11a. Specifically, the shoulder circumferential direction narrow groove 12 is provided with one end portion 12a closely spaced within a range of 5 mm or less with respect to the terminal end 11a of the one shoulder lug groove 11 (FIGS. 2, 3). The area surrounded by a broken line in FIG. 5 is provided at a distance of 7 mm or more with respect to the terminal end 11 a of the other shoulder lug groove 11.

  The shoulder sipe 13 is provided extending along the tire width direction so as to intersect the tire circumferential direction. The shoulder sipes 13 are not communicated with the shoulder circumferential narrow groove 12 or the outermost shoulder main groove 22B in the tire width direction but terminate in the shoulder rib 23B, and are provided in the tire circumferential direction. It is provided alternately in the direction. The shoulder sipe 13 is formed narrower than the shoulder circumferential narrow groove 12 in a range where the groove width is 0.5 mm or more and 1.5 mm or less. The shoulder sipe 13 is formed shallower than the main groove 22 in a groove depth range of 4.0 mm or more and 9.0 mm or less. The shoulder sipe 13 is provided so as to intersect the grounding end T. The length of the shoulder sipe 13 in the extending direction is shorter than that of the shoulder lug groove 11. The shoulder sipe 13 is provided in parallel with the shoulder lug groove 11.

  Further, the shoulder sipe 13 is provided with a terminal end 13 a near the shoulder main groove 22 </ b> B in the vicinity of the extending direction of the shoulder circumferential narrow groove 12. Specifically, the shoulder sipe 13 is provided with the terminal end 13a close to and within a range of 5 mm or less with respect to the middle of the extension of the shoulder circumferential narrow groove 12. The shoulder sipe 13 is provided to be inclined at an inclination angle in the range of 2 degrees to 15 degrees with respect to the tire width direction. The shoulder sipe 13 may be formed to be curved in the extending direction, though not explicitly shown in the drawing. The inclination angle in this case is an angle formed by a center line passing through the center of the groove width of the shoulder sipe 13 and a base line in the tire width direction at each end of the shoulder sipe 13.

  As described above, the shoulder lug groove 11, the shoulder circumferential narrow groove 12 in which the end 12 a is close to the terminal end 11 a of the shoulder lug groove 11, and the terminal end 13 a is in the vicinity of the extension of the shoulder circumferential narrow groove 12. The combination with the shoulder sipe 13 is a shoulder groove unit 10, and a plurality of the shoulder groove units 10 are provided side by side in the tire circumferential direction. The shoulder groove unit 10 is configured such that a shoulder lug groove 11 and a shoulder circumferential narrow groove 12 are bent into a U-shape.

  The pneumatic tire 1 according to the present embodiment includes an inner lug groove 31 on the tread surface 21 of the inner rib 23A that is provided on the inner side in the tire width direction of the shoulder main groove 22B and is adjacent to the shoulder rib 23B across the shoulder main groove 22B. , And an inner circumferential narrow groove 32 are provided. There is no other groove in the inner rib 23A.

  The inner lug groove 31 is provided extending along the tire width direction so as to intersect the tire circumferential direction. The inner lug groove 31 is provided with one end communicating with the shoulder main groove 22B and the other end terminating in the inner rib 23A. The inner lug groove 31 is formed narrower than the main groove 22 in a range where the groove width is 1.5 mm or greater and 4.0 mm or less. Further, the inner lug groove 31 is formed shallower than the main groove 22 in a groove depth range of 2.0 mm or more and 9.0 mm or less.

  Further, the inner lug groove 31 is provided to be inclined at an inclination angle in the range of 2 degrees to 15 degrees with respect to the tire width direction. The inner lug groove 31 may be formed to be curved in the extending direction, although it is not clearly shown in the drawing. In this case, the inclination angle is an angle formed by the center line passing through the center of the groove width of the inner lug groove 31 and the base line in the tire width direction at each end of the inner lug groove 31.

  The inner circumferential narrow groove 32 is provided extending along the tire circumferential direction. The inner circumferential narrow groove 32 ends at both ends in the inner rib 23 </ b> A and is provided away from the inner lug groove 31. The inner circumferential narrow groove 32 is formed narrower than the inner lug groove 31 in a range where the groove width is 0.4 mm or more and 2.0 mm or less. Further, the inner circumferential narrow groove 32 is formed shallower than the inner lug groove 31 in a groove depth range of 1.0 mm to 7.0 mm.

  Further, the inner circumferential narrow groove 32 has one end portion 32a that is terminated close to the two inner lug grooves 31 that are adjacent in the tire circumferential direction, and is close to the terminal end 31a of the one inner lug groove 31. Rather than the terminal end 31a of the other inner lug groove 31. Specifically, the inner circumferential narrow groove 32 is provided such that one end portion 32a is closely spaced within a range of 5 mm or less with respect to the terminal end 31a of the one inner lug groove 31 (FIGS. 2, 3 and The area surrounded by a broken line in FIG. 5 is provided at a distance of 7 mm or more with respect to the terminal end 31a of the other inner lug groove 31.

  Thus, the inner groove unit 31 is a combination of the inner lug groove 31 and the inner circumferential narrow groove 32 in which the end portion 32a is close to the terminal end 31a of the inner lug groove 31. A plurality are arranged side by side in the direction. The inner groove unit 30 has an inner lug groove 31 and an inner circumferential narrow groove 32 arranged in a bent shape.

  Further, in the pneumatic tire 1 of the present embodiment, the inner main groove 22A is disposed on the tire equator plane CL, and the land portions 23 and the grooves on both sides in the tire width direction are disposed point-symmetrically between the tire equator plane CL. Yes. Although not shown in the figure, in the pneumatic tire 1 of the present embodiment, the inner main groove 22A is disposed on the tire equatorial plane CL, and the land portions 23 and grooves on both sides in the tire width direction are interposed between the tire equatorial plane CL. May be arranged in line symmetry.

  Further, in the above-described embodiment, three main grooves 22 are provided, and the central inner main groove 22A is disposed on the tire equatorial plane CL, and the inner ribs 23A and the shoulder ribs are respectively formed on the tire equatorial plane CL on the outer side in the tire width direction. 23B is formed. Not limited to this configuration, for example, four main grooves 22 are provided, a central rib disposed on the tire equatorial plane CL is disposed on the inner side of the inner rib 23A in the tire width direction, and no groove is provided in the central rib. The inner rib 23A and the shoulder rib 23B on the outer side in the tire width direction are configured as described above.

  As described above, the pneumatic tire 1 according to the present embodiment terminates in the shoulder rib 23B without extending to the shoulder main groove 22B and extending along the tire width direction to the outermost shoulder rib 23B in the tire width direction. A plurality of shoulder lug grooves 11 are provided in the tire circumferential direction, and both ends of the shoulder lug grooves 11 extend in the tire circumferential direction and terminate in the shoulder rib 23B. Shoulder circumferential narrow grooves 12 provided within 5 mm apart from each other, and extending along the tire width direction on the inner rib 23A adjacent to the inner side in the tire width direction of the shoulder rib 23B, and one end of the shoulder main groove 22B. A plurality of inner lug grooves 31 that end in the inner rib 23A and that are provided in the tire circumferential direction, and extend along the tire circumferential direction, and both ends are connected to the inner rib 23A. It comprises an inner circumferential narrow groove 32 provided apart within 5mm one end 32a is against end 31a of the inner lug groove 31 with terminating in 23A.

  According to the pneumatic tire 1, the lug grooves 11 and 31 and the circumferential narrow grooves 12 and 32 terminate in the ribs 23 </ b> A and 23 </ b> B, so that the land portion 23 is not partitioned into blocks and extends along the tire circumferential direction. Since the ribs are continuously formed, the rigidity of the land portion 23 is not lowered, and the steering stability performance on the dry road surface can be maintained. Moreover, by having the circumferential narrow grooves 12 and 32, it is possible to compensate for edge components in the direction intersecting the tire circumferential direction, and to improve the snow turning performance (snow traction performance) when the chain is mounted. In particular, since one end 12a, 32a of the circumferential narrow grooves 12, 32 is provided within 5 mm away from the terminal ends 11a, 31a of the lug grooves 11, 31, while suppressing a decrease in rigidity, By imparting flexibility to one end 12a, 32a of the directional groove 12, 32 and the land portion 23 in the vicinity of the terminal end 11a, 31a of the lug groove 11, 31, the circumferential narrow groove 12, 32 and the lug The edge effect of the grooves 11 and 31 can be improved, and the turning performance on snow (snow traction performance) when the chain is attached can be enhanced. As a result, it is possible to improve the turning performance on snow without impairing the steering stability performance on the dry road surface.

  In addition, by providing the flexibility of the land portion 23 in the vicinity of one end 12a, 32a of the circumferential narrow groove 12, 32 and the end 11a, 31a of the lug groove 11, 31, the circumferential narrow groove 12, 32 and the lug grooves 11, 31 to improve the edge effect, and to significantly obtain the effect of improving the turning performance on snow (snow traction performance) when the chain is mounted, It is preferable that 32a is provided close to and separated from the terminal ends 11a and 31a of the lug grooves 11 and 31 within a range of 0.5 mm to 5 mm.

  Further, in the pneumatic tire 1 of the present embodiment, the shoulder ribs 23B and the inner ribs 23A are respectively provided with the tire equator plane CL as a boundary, and as shown in FIG. In the tire width direction, the shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 are preferably continuous in the tire circumferential direction.

  According to the pneumatic tire 1, the shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 overlap with each other on the tire width direction view from the tire equatorial plane CL, and the shoulder width view on the tire width direction view. There is always at least one of the circumferential narrow groove 12 and the inner circumferential narrow groove 32. For this reason, the edge component which cross | intersects a tire circumferential direction can always be effective by the shoulder circumferential direction fine groove 12 and the inner side circumferential direction fine groove 32 in a tire circumferential direction, and the turning performance on snow (snow traction performance) at the time of chain wearing It is possible to obtain the effect of enhancing the remarkably.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 4, the shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 have an angle θ <b> 1 of 5 degrees or more and 15 degrees or less with respect to the tire circumferential direction. It is preferable to be disposed at an angle of θ2.

  According to this pneumatic tire 1, when the angles θ 1 and θ 2 are less than 5 degrees and the shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 are substantially parallel to the main groove 22, The part 23 falls down together with the main groove 22 and the rigidity of the land part 23 tends to be lowered. On the other hand, when the angles θ1 and θ2 exceed 15 degrees, the effect of compensating for the edge component tends to be reduced. Accordingly, in order to improve the turning performance on snow without impairing the steering stability performance on the dry road surface, it is preferable to set the angles θ1 and θ2 to 5 degrees or more and 15 degrees or less with respect to the tire circumferential direction.

  Further, in the pneumatic tire 1 of the present embodiment, the shoulder ribs 23B and the inner ribs 23A are respectively provided with the tire equator plane CL as a boundary, and as shown in FIG. , The shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 are preferably arranged so as to be inclined in different directions.

  According to this pneumatic tire 1, since the shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 are arranged to be inclined in the opposite direction of the tire width direction with respect to the tire circumferential direction, various directions are possible. The edge component can be applied to the input from, and the effect of improving the turning performance on the snow (snow traction performance) when the chain is attached can be significantly obtained.

  In the pneumatic tire 1 of the present embodiment, the shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 have a groove width of 0.4 mm or more and 2.0 mm or less, and the shoulder lug groove 11 and the inner lug groove 31. It is preferable that the groove width is narrower than that.

  According to this pneumatic tire 1, by defining the groove widths of the shoulder circumferential narrow groove 12 and the inner circumferential narrow groove 32 as described above, a groove that is not too wide that can suppress a decrease in rigidity of the land portion 23. The width may be within a range of a groove width that is not so narrow that clogging due to snow hardly occurs.

  Further, in the pneumatic tire 1 of the present embodiment, the shoulder ribs 23B and the inner ribs 23A are respectively provided with the tire equator plane CL as a boundary, and as shown in FIG. The shoulder lug groove 11 and the inner lug groove 31 are preferably arranged to be inclined in different directions.

  According to the pneumatic tire 1, the shoulder lug groove 11 and the inner lug groove 31 are arranged in a direction opposite to the tire circumferential direction with respect to the tire width direction, so that input from various directions is possible. On the other hand, the edge component can be applied, and the effect of improving the turning performance on snow (snow traction performance) when the chain is attached can be remarkably obtained.

  In the present example, performance tests on the turning performance on snow and the steering stability performance on a dry road surface were performed for a plurality of types of pneumatic tires having different conditions (see FIG. 6).

  In this performance test, a pneumatic tire (test tire) having a tire size of 185 / 65R15 and a main groove depth of 7 mm is assembled on a regular rim of 15 × 6 J, filled with a regular internal pressure of 180 kPa, and a test vehicle (exhaust It was mounted on a 1.5L front drive vehicle.

  The method for evaluating snow turning ability is run on a snow test course assuming a city area with the above test vehicle with a chain attached to the drive wheels, and a 10-step evaluation is performed by a test driver. This evaluation indicates that the higher the score, the better the turning performance on snow.

  The method for evaluating the driving stability performance on the dry road surface is carried out on a test course on the dry road surface using the test vehicle, and a 10-step evaluation is performed by a test driver. This evaluation shows that the higher the score, the better the steering stability performance on the dry road surface.

  In FIG. 6, the conventional pneumatic tire does not have a circumferential narrow groove as shown in the configuration diagram. The pneumatic tire of Comparative Example 1 is provided with circumferential narrow grooves continuously in the tire circumferential direction as shown in the configuration diagram. In the pneumatic tire of Comparative Example 2, the circumferential narrow groove terminates in the land portion as shown in the configuration diagram, but the inner land portion is divided in the sipe tire circumferential direction. 6 and 7, the pneumatic tires of Examples 1 to 10 have a circumferential narrow groove that terminates in the land and is separated from the terminal of the lug groove within 5 mm as shown in the configuration diagram. As shown in the test results of FIGS. 6 and 7, it can be seen that the pneumatic tires of Examples 1 to 10 have improved turning performance on snow without impairing the steering stability performance on the dry road surface. .

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 10 Shoulder groove unit 11 Shoulder lug groove 11a Termination 12 Shoulder circumferential direction narrow groove 12a End part 13 Shoulder sipe 13a Termination 21 Tread surface 22 Main groove 22A Inner main groove 22B Shoulder main groove 23 Land part 23A Inner side Rib 23B Shoulder rib 30 Inner groove unit 31 Inner lug groove 31a Termination 32 Inner circumferential narrow groove 32a End CL Tire equatorial plane (tire equatorial line)
T Grounding end θ1, θ2 angle

Claims (6)

A main groove extending along the tire circumferential direction and arranged in the tire width direction in the tread portion; and a plurality of ribs formed in the tire width direction by the main grooves and continuous along the tire circumferential direction; In a pneumatic tire comprising:
To the shoulder rib on the outer side in the tire width direction of the main groove on the outermost side in the tire width direction,
A shoulder lug groove that extends along the tire width direction and terminates in the shoulder rib without communicating with the main groove on the outermost side in the tire width direction, and is provided in the tire circumferential direction; and
A shoulder circumferential narrow groove that extends along the tire circumferential direction and ends at both ends in the shoulder rib and one end is provided within 5 mm away from the end of the shoulder lug groove;
With
To the inner rib adjacent to the inner side in the tire width direction of the shoulder rib,
An inner lug groove extending along the tire width direction, one end communicating with the main groove on the outermost side in the tire width direction, the other end terminating in the inner rib, and a plurality of inner lug grooves provided in the tire circumferential direction;
An inner circumferential narrow groove that extends along the tire circumferential direction and ends at both ends within the inner rib and one end portion is provided within 5 mm away from the end of the inner lug groove;
A pneumatic tire comprising:   The shoulder rib and the inner rib are respectively provided with a tire equatorial plane as a boundary, and the shoulder circumferential narrow groove and the inner circumferential narrow groove as viewed in the tire width direction on one outer side in the tire width direction from the tire equatorial plane. The pneumatic tire according to claim 1, wherein the tire is continuous in a tire circumferential direction.   The pneumatic tire according to claim 1 or 2, wherein the shoulder circumferential narrow groove and the inner circumferential narrow groove are arranged to be inclined at an angle of 5 degrees or more and 15 degrees or less with respect to the tire circumferential direction.   The shoulder rib and the inner rib are respectively provided with a tire equator plane as a boundary, and the shoulder circumferential narrow groove and the inner circumferential narrow groove are different from each other on the outer side in the tire width direction from the tire equator plane. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is disposed so as to be inclined in a direction.   2. The shoulder circumferential narrow groove and the inner circumferential narrow groove have a groove width of 0.4 mm or more and 2.0 mm or less, and are narrower than the shoulder lug groove and the inner lug groove. To 4. The pneumatic tire according to any one of 4 to 4.   The shoulder rib and the inner rib are respectively provided with a tire equatorial plane as a boundary, and the shoulder lug groove and the inner lug groove are inclined in different directions on the outer side in the tire width direction from the tire equatorial plane. The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is arranged as described above.

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