JP2016107912A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve turning performance on a wet road surface while maintaining steering stability on a dry road surface.SOLUTION: A pneumatic tire 1 comprises a tread part 2 including a first main groove 3, and a second main groove 4 adjacent to the first main groove 3 and disposed to the outer side in a tire axial direction with respect to the first main groove 3. A first land part 9 is formed between the first main groove 3 and the second main groove 4. The first land part 9 includes: first lug grooves 15 each having an inner end 15e extending from the first main groove 3 and terminating inside the first land part 9; second lug grooves 16 each having an inner end 16e extending from the second main groove 4 and terminating inside the first land part 9; and vertical slots 17 which communicate with the second lug grooves 16, and of which both ends 17e and 17e terminate inside the first land part 9. The tire axial direction length of each second lug groove 16 is 50% or more of the tire axial direction maximum width of the first land part 9.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire having improved turning performance on a wet road surface while maintaining steering stability performance on a dry road surface.

  In recent years, pneumatic tires having excellent wet performance have been desired. In order to improve the wet performance of the pneumatic tire, for example, a lateral groove that completely crosses the land portion may be provided in the land portion provided in the tread portion.

  However, the pneumatic tire as described above has a problem that the rigidity of the land portion of the tread portion is reduced, and the steering stability performance on the dry road surface and the wet road surface is deteriorated.

JP 2012-116306 A

  The present invention has been devised in view of the above problems, and a main object of the present invention is to provide a pneumatic tire capable of improving turning performance on a wet road surface while maintaining steering stability performance on a dry road surface. It is said.

  The present invention is a pneumatic tire having a tread portion, wherein the tread portion is provided with a plurality of main grooves extending continuously in a tire circumferential direction, and the main groove is a first main groove and A second main groove adjacent to the first main groove and provided on the outer side in the tire axial direction than the first main groove, and between the first main groove and the second main groove, A first land portion is formed. The first land portion includes a first lug groove having an inner end extending from the first main groove and terminating in the first land portion, and the second main groove. A second lug groove having an inner end that extends and ends in the first land portion; and a vertical slot that communicates with the second lug groove and ends at both ends in the first land portion. The length of the groove in the tire axial direction is 50% or more of the maximum width in the tire axial direction of the first land portion.

  In the pneumatic tire according to the present invention, the tread portion has an asymmetric pattern in which a direction of mounting on the vehicle is specified, and the asymmetric pattern is located on the inner side of the vehicle when the tire is mounted on the vehicle. It is preferable that the second main groove is provided on the innermost tread end side including the inner tread end.

  In the pneumatic tire according to the present invention, it is desirable that the first lug groove and the second lug groove are inclined with respect to the tire axial direction.

  In the pneumatic tire according to the present invention, it is preferable that the first lug groove and the second lug groove are inclined in the same direction.

  In the pneumatic tire according to the present invention, the first lug grooves and the second lug grooves are alternately arranged in the tire circumferential direction, and both ends of the vertical slot are adjacent to each other in the tire circumferential direction. It is desirable that the lug groove is positioned in the vicinity thereof without communicating with the inner end.

  In the pneumatic tire according to the present invention, it is desirable that the longitudinal slot extends along the tire circumferential direction.

  In the pneumatic tire according to the present invention, it is desirable that the groove depth of the vertical slot is 1 to 2 mm.

  In the pneumatic tire according to the present invention, it is desirable that the groove width of the second main groove is the largest among the groove widths of the main grooves.

  The tread portion of the pneumatic tire according to the present invention includes a first main groove and a second main groove that is adjacent to the first main groove and that is provided outside the first main groove in the tire axial direction. One land area is provided. The first land portion has a first lug groove having an inner end extending from the first main groove and terminating in the first land portion, and an inner end extending from the second main groove and terminating in the first land portion. Two lug grooves are provided.

  Since these first lug groove and second lug groove do not completely cross the first land portion, the first land portion is formed as a rib having high circumferential rigidity and lateral rigidity continuously in the tire circumferential direction. The Such a first land portion is useful for improving the steering stability on the dry road surface. Further, when traveling on a wet road surface, the water film below the first land portion passes through the first lug groove or the second lug groove to the first main groove or the second main groove on both sides of the first land portion. It can be discharged efficiently. Moreover, since the length of the second lug groove in the tire axial direction is 50% or more of the maximum width of the first land portion in the tire axial direction, more water is supplied to the tread end side (second main groove). Side).

  Further, the tread portion of the pneumatic tire of the present invention is provided with a vertical slot that communicates with the second lug groove and ends at both ends in the first land portion. Such a vertical slot can provide an edge component in the tire circumferential direction to the first land portion without reducing the lateral rigidity of the first land portion. Accordingly, in the pneumatic tire of the present invention, the vertical slot can increase the frictional force with respect to the road surface when turning on a wet road surface. In addition, when turning on a wet road surface, the vertical slot is compressed and deformed in such a direction as to reduce the groove width by a lateral force acting on the first land portion. Such compression deformation of the vertical slot causes water in the vertical slot to be vigorously discharged to the second main groove through the second lug groove. The pneumatic tire of the present invention can exhibit high turning performance on a wet road surface by these synergistic actions.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. It is an enlarged view of the tread part inside the vehicle of FIG. It is an enlarged view of the tread part of the vehicle outer side of FIG. It is an expanded view of the tread part of other embodiment. It is an expanded view of the tread part of other embodiment. It is an expanded view of the tread part of a comparative example. It is an expanded view of the tread part of another comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a development view of a tread portion 2 of a pneumatic tire 1 showing an embodiment of the present invention. A pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is suitably used as a pneumatic tire for a passenger car, for example.

  As shown in FIG. 1, the tread portion 2 includes an asymmetric tread pattern in which the mounting direction of the vehicle is specified. The tread portion 2 has an outer tread end To positioned on the vehicle outer side when the tire 1 is mounted on the vehicle, and an inner tread end Ti positioned on the vehicle inner side when the vehicle is mounted. The direction of mounting on the vehicle is displayed, for example, in characters on a sidewall (not shown).

  Each of the “tread ends” To and Ti is grounded on a flat surface at a camber angle of 0 degrees by applying a normal load to a normal tire 1 that is assembled with a normal rim and filled with a normal internal pressure. Is defined as the contact position on the outermost side in the tire axial direction. In the normal state, the distance in the tire axial direction between the tread ends To and Ti is determined as the tread contact width TW. Unless otherwise noted, the dimensions and the like of each part of the tire are values measured in a normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, ETRTO Then "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “maximum air pressure”, TRA is the table “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO. When the tire is for a passenger car, the normal internal pressure is 180 kPa.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “maximum load capacity”, TRA is “TIRE LOAD” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO. When the tire is for a passenger car, the normal load is a load corresponding to 88% of the load.

  The tread portion 2 of the present embodiment is provided with a plurality of main grooves extending continuously in the tire circumferential direction.

  In the present embodiment, the main groove includes a first main groove 3, a second main groove 4, a third main groove 5, and a fourth main groove 6. The first main groove 3 is provided on the vehicle inner side than the tire equator C. The second main groove 4 is provided adjacent to the first main groove 3 on the innermost tread end Ti side. The third main groove 5 is provided on the outermost tread end To side. The fourth main groove 6 is provided adjacent to the third main groove 5 on the vehicle outer side than the tire equator C.

  Each of the main grooves 3 to 6 is linear along the tire circumferential direction. The main grooves 3 to 6 improve the wet performance because the water in the grooves is smoothly discharged rearward in the rotation direction.

  In this embodiment, the groove width of the main groove inside the vehicle is formed larger than the groove width of the main groove outside the vehicle. In general, a larger lateral force acts on the land portion on the outer side of the vehicle during cornering than on the land portion on the inner side of the vehicle. For this reason, in order to make the turning force to the vehicle outer side and the vehicle inner side uniform and to improve the steering stability performance, the tire axial rigidity of the land portion corresponding to the lateral force is required. Therefore, it is desirable that the groove width W2 of the second main groove 4 is larger than the groove width W3 of the third main groove 5. Further, the land portion on the tire equator C side is less likely to discharge the water film below each land portion than the land portions on the tread ends To and Ti sides on both sides. For this reason, it is desirable that the groove widths W1 and W4 of the first main groove 3 and the fourth main groove 6 are larger than the groove width W3 of the third main groove 5 to improve drainage performance. Further, in order to effectively discharge the water film below the land portion between the first main groove 3 and the second main groove 4 where a large lateral force hardly acts, in the present embodiment, the second main groove 4 The groove width W2 is the largest. In addition, the groove width of each main groove is not limited to such an aspect.

  From the viewpoint of effectively exhibiting the above-described action, the groove width W1 of the first main groove 3 is preferably 4.5% to 8.5% of the tread ground contact width TW. The groove width W2 of the second main groove 4 is preferably 5.5% to 9.5% of the tread ground contact width TW. The groove width W3 of the third main groove 5 is preferably 1.5% to 5.5% of the tread ground contact width TW. The groove width W4 of the fourth main groove 6 is preferably 4% to 8% of the tread ground contact width TW. Although not particularly limited, the groove depth (not shown) of each of the main grooves 3 to 6 is preferably 7.0 to 9.5 mm.

  In the tread portion 2, a first land portion 9, a second land portion 10, a third land portion 11, a fourth land portion 12, and a fifth land portion 13 are formed by the main grooves 3 to 6.

  The first land portion 9 is divided into a first main groove 3 and a second main groove 4. The second land portion 10 is divided by the second main groove 4 and the inner tread end Ti. The third land portion 11 is divided by the outer tread end To and the third main groove 5. The fourth land portion 12 is divided into a third main groove 5 and a fourth main groove 6. The fifth land portion 13 is divided into a first main groove 3 and a fourth main groove 6.

  FIG. 2 is an enlarged view of the first land portion 9 and the second land portion 10. As shown in FIG. 2, the first land portion 9 is provided with a first lug groove 15, a second lug groove 16, and a vertical slot 17.

  The first lug groove 15 has an inner end 15 e extending from the first main groove 3 and terminating in the first land portion 9. The first lug groove 15 of the present embodiment has a groove width that gradually increases toward the first main groove 3 side. Thereby, the water in the groove is smoothly discharged into the first main groove 3.

  The first lug groove 15 has a first groove edge 15a extending on one side in the tire circumferential direction and a second groove edge 15b extending on the other side in the tire circumferential direction. The first groove edge 15a of this embodiment extends linearly from the inner end 15e to the first main groove 3. The second groove edge 15b of the present embodiment extends in an arc from the inner end 15e to the first main groove 3. Such a 1st lug groove 15 maintains the rigidity of the 1st land part 9 highly.

  The first lug groove 15 is inclined with respect to the tire axial direction. Thereby, the water in the groove is discharged more smoothly using the ground pressure during straight traveling and the lateral force during turning.

  In order to effectively exhibit the above-described action, the angle θ1 of the first lug groove 15 with respect to the tire axial direction is preferably 30 to 50 degrees. The angle θ1 of the first lug groove 15 as in the present embodiment is defined by the arrangement angle of the first groove edge 15a formed in a straight line.

  The length L1 of the first lug groove 15 in the tire axial direction is preferably 25% to 45% of the maximum width Wa of the first land portion 9 in the tire axial direction. That is, when the length L1 of the first lug groove 15 is less than 25% of the maximum width Wa of the first land portion 9, there is a possibility that the wet performance cannot be improved. When the length L1 of the 1st lug groove 15 exceeds 45% of the maximum width Wa of the 1st land part 9, there exists a possibility that the rigidity of the 1st land part 9 may fall.

  In order to effectively exhibit the above-described action, the maximum groove width W5 of the first lug groove 15 is preferably 20% to 30% of the maximum width Wa in the tire axial direction of the first land portion 9. The groove depth (not shown) of the first lug groove 15 is preferably 65% to 75% of the groove depth of the first main groove 3. The groove width of the first lug groove 15 as in the present embodiment is defined by the distance between the first groove edge 15a extending linearly and the groove edge in the perpendicular direction.

  The second lug groove 16 has an inner end 16 e extending from the second main groove 4 and terminating in the first land portion 9. Thus, since the 1st lug groove 15 and the 2nd lug groove 16 do not cross the 1st land part 9 completely, the 1st land part 9 has high circumferential direction rigidity and lateral rigidity continuously in the tire circumferential direction. It is formed as a rib having Thereby, the 1st land part 9 can improve the steering stability on the dry road surface. In addition, when traveling on a wet road surface, the water film below the first land portion 9 passes through the first lug groove 15 or the second lug groove 16, and the first main groove 3 or the first groove on both sides of the first land portion 9. 2 can be efficiently discharged into the main groove 4.

  The second lug groove 16 has a groove width W6 that gradually increases toward the second main groove 4. Such a second lug groove 16 can smoothly discharge the water in the groove to the second main groove 4. In the present embodiment, the second lug groove 16 extends linearly.

  The second lug grooves 16 are arranged alternately with the first lug grooves 15 in the tire circumferential direction. Thereby, the tire axial direction rigidity of the 1st land part 9 is equalized over a tire peripheral direction. “Alternately arranged” refers to an aspect in which the inner end 15e of the first lug groove 15 and the inner end 16e of the second lug groove 16 are displaced in the tire circumferential direction. In order to effectively exert the above-described action, the tire circumferential direction distance La between the inner end 15e of the first lug groove 15 and the inner end 16e of the second lug groove 16 is preferably It is 25% or more of the tire circumferential direction pitch P1, more preferably 30% or more.

  In the present embodiment, the second lug groove 16 is connected to the second main groove 4 provided on the innermost tread end Ti side. As a result, even in the land portion on the vehicle inner side where a lateral force smaller than the lateral force acting on the land portion outside the vehicle acts, the water in the groove is smoothly drained using the lateral force on the inner tread end Ti side (the first side). Since it can be discharged into the two main grooves 4), the wet performance is improved. The second main groove 4 to which the second lug groove 16 is connected may be provided on the outermost tread end To side.

  The tire axial direction length L2 of the second lug groove 16 is 50% or more of the tire axial direction maximum width Wa of the first land portion 9. Thereby, more water can be reliably discharged to the inner tread end Ti side (second main groove 4). In order to exert such an action more reliably, the tire axial direction length L2 of the second lug groove 16 is preferably 55% or more of the tire axial direction maximum width Wa of the first land portion 9. In addition, when the tire axial direction length L2 of the 2nd lug groove 16 is too large, there exists a possibility that the pattern rigidity of the 1st land part 9 may fall. For this reason, the tire axial direction length L2 of the 2nd lug groove 16 becomes like this. Preferably, it is 70% or less of the tire axial direction maximum width Wa of the 1st land part 9, More preferably, it is 65% or less.

  The second lug groove 16 is inclined in the tire axial direction. As a result, the water in the second lug groove 16 is also smoothly discharged into the second main groove 4 using the lateral force during turning and the ground pressure during straight running. In order to effectively exhibit such an action, the angle θ2 of the second lug groove 16 with respect to the tire axial direction is preferably 30 to 50 degrees. The angle θ2 of the second lug groove 16 is defined by the angle of the groove center line 16c that connects the middle position of the tire circumferential direction line passing between the groove edges of the second lug groove 16 in the tire axial direction.

  The second lug groove 16 is inclined in the same direction as the first lug groove 15. Thereby, the tire axial direction rigidity of the 1st land part 9 can be closely approached over a tire peripheral direction. Accordingly, the steering stability performance on the dry road surface and the turning performance on the wet road surface are greatly improved.

  In order to improve the turning performance of the wet road surface while maintaining the steering stability on the dry road surface, the groove width W6 of the second lug groove 16 is preferably 15% of the maximum width Wa in the tire axial direction of the first land portion 9. ~ 25%. The groove depth (not shown) of the second lug groove 16 is preferably 65% to 75% of the groove depth of the second main groove 4.

  The vertical slot 17 communicates with the second lug groove 16, and both ends 17 e and 17 e terminate in the first land portion 9. Such a vertical slot 17 can provide an edge component in the tire circumferential direction to the first land portion 9 without reducing the lateral rigidity of the first land portion 9. Therefore, the vertical slot 17 of the present embodiment can increase the frictional force on the road surface when turning on a wet road surface. Further, when turning on a wet road surface, the vertical slot 17 may be compressed and deformed in such a direction as to reduce the groove width W7 due to a lateral force acting on the first land portion 9. Such compression deformation of the vertical slot 17 causes the water in the vertical slot 17 to be vigorously discharged to the second main groove 4 via the second lug groove 16. Therefore, the turning performance on the wet road surface is greatly improved.

  The vertical slot 17 extends along the tire circumferential direction. As a result, the lateral force during cornering is large and acts in the vicinity of the vertical slot 17, so that a compressive deformation occurs in such a direction that the groove width W 7 of the vertical slot 17 is further reduced. Thereby, the water in the vertical slot 17 is more smoothly discharged into the second main groove 4 during turning. Note that “extend along the tire circumferential direction” means that the angle θ3 of the vertical slot 17 with respect to the tire circumferential direction is 5 degrees or less. The angle θ3 of the vertical slot 17 is defined by a virtual line 17c that connects both ends 17e and 17e of the vertical slot 17 with a straight line.

  In the present embodiment, both ends 17e and 17e of the vertical slot 17 are located in the vicinity of the inner end 15e of the first lug groove 15 and do not communicate with the inner end 15e of the first lug groove 15. Such a vertical slot 17 maintains the rigidity of the first land portion 9 at a large level, and the water in the vertical slot 17 is surely discharged to the inner tread end Ti side (second main groove 4).

  “The outer end 17e of the vertical slot 17 is located in the vicinity of the inner end 15e of the first lug groove 15” means that, for example, the outer end 17e of the vertical slot 17 and a first The shortest distance Lb in the tire circumferential direction with the inner end 15e of the lug groove 15 is 5% to 15% of the maximum width Wa in the tire axial direction of the first land portion 9. When the shortest distance Lb exceeds 15% of the maximum width Wa of the first land portion 9, the tire circumferential direction length L3 of the vertical slot 17 becomes small, and the water film under the first land portion 9 is effectively removed. There is a risk that it cannot be accumulated.

  The vertical slots 17 are preferably provided between the inner ends 15e, 15e of the first lug grooves 15 adjacent in the tire circumferential direction. Thereby, since the overlapping part which the vertical slot 17 and the 1st lug groove 15 overlap in a tire circumferential direction is not formed, or the said overlapping part becomes small, the tire axial direction rigidity of the 1st land part 9 can be maintained large. In order to maintain the tire axial rigidity of the first land portion 9 while ensuring the water film accumulation effect by the vertical slot 17, the tire circumferential direction length L 3 of the vertical slot 17 is the tire circumferential direction of the first lug groove 15. 75% to 95% of the pitch P1 is desirable.

  The vertical slot 17 of the present embodiment communicates with the second lug groove 16 at a position displaced in the tire circumferential direction from an intermediate position of the tire circumferential length L3. The second lug groove 16 extends from the longitudinal slot 17 toward the inner tread end Ti side in the direction of displacement from the intermediate position. Thereby, the corner 18 on the obtuse angle side formed between the vertical slot 17 of the first land portion 9 and the second lug groove 16 is provided on the outer side in the tire circumferential direction of the vertical slot 17. A decrease in pattern rigidity is suppressed. When the inner end 16e of the second lug groove 16 is excessively displaced from the intermediate position of the vertical slot 17, the distance La between the inner end 16e of the second lug groove 16 and the inner end 15e of the first lug groove 15 is small. Therefore, the tire axial direction rigidity step of the first land portion 9 may be increased. From this point of view, the tire circumferential direction distance Lc between the outer end 17e in the tire circumferential direction of the vertical slot 17 and the inner end 16e of the second lug groove 16 is 20% to the tire circumferential direction length L3 of the vertical slot 17. 40% is desirable.

  The average groove width W7 of the vertical slot 17 suppresses a decrease in the lateral rigidity of the first land portion 9 while effectively generating the compressive deformation of the vertical slot 17 due to the lateral force during turning. 3% to 13% of the maximum width Wa of the portion 9 in the tire axial direction is desirable. From the same viewpoint, the groove depth (not shown) of the vertical slot 17 is preferably about 1 to 2 mm.

  Thus, by providing the 1st lug groove 15, the 2nd lug groove 16, and the vertical slot 17, lateral force smaller than the 3rd land part 11 and the 4th land part 12 of the vehicle outside at the time of turning driving | running | working Even in the first land portion 9 on the vehicle inner side where the water acts, the water film below the first land portion 9 can be effectively discharged smoothly into the first main groove 3 and the second main groove 4. Therefore, high turning performance on a wet road surface can be exhibited.

  The second land portion 10 is provided with an inner shoulder lug groove 20, a first inner shoulder sipe 21, and a second inner shoulder sipe 22.

  The inner shoulder lug groove 20 has an inner end 20 i extending from the inner tread end Ti to the second main groove 4 side and terminating in the second land portion 10. Such an inner shoulder lug groove 20 can smoothly discharge the water film on the tread surface of the second land portion 10 to the inner tread end Ti while maintaining the rigidity of the second land portion 10 high.

  The first inner shoulder sipe 21 connects the inner end 20 i of the inner shoulder lug groove 20 and the second main groove 4. In the present embodiment, the second land portion 10 has a large pattern rigidity on the tire equator C side.

  The second inner shoulder sipe 22 extends from the second main groove 4 to the inner tread end Ti side and terminates in the second land portion 10. Such a second inner shoulder sipe 22 can absorb the water film of the second land portion 10 and discharge it to the second main groove 4. The 2nd inner side shoulder sipe 22 is not limited to such an aspect, For example, the aspect which crosses the 2nd land part 10 may be sufficient.

  FIG. 3 is an enlarged view of the third land portion 11 to the fifth land portion 13. As shown in FIG. 3, the third land portion 11 includes a first lateral groove 25 that crosses the third land portion 11 and a first sipe 26 that is disposed between the first lateral grooves 25, 25 adjacent to each other in the tire circumferential direction. Are alternately provided in the tire circumferential direction.

  The first lateral groove 25 includes an outer portion 27 extending from the outer tread end To, and a sipe portion 28 that continues to the outer portion 27 and communicates with the third main groove 5. Such first lateral grooves 25 discharge the water in the outer portion 27 to the outer tread end To, thereby improving the wet performance. Moreover, since the sipe part 28 maintains the tire circumferential direction rigidity of the 3rd land part 11 high, abrasion resistance performance is improved. Further, the sipe portion 28 absorbs a water film between the road surface and the tread surface of the third land portion 11, which is useful for improving the wet performance. In this specification, the “sipe part” has a cut shape with a width of less than 1.5 mm.

  In the present embodiment, the outer portion 27 and the sipe portion 28 are inclined in the same direction with respect to the tire axial direction. Thereby, the rigidity fall of the 3rd land part 11 in the crossing position of the outer side part 27 and the sipe part 28 is suppressed. In the present embodiment, the outer portion 27 and the sipe portion 28 are smoothly continuous. Such first lateral grooves 25 maintain the rigidity of the third land portion 11 higher. “Smoothly continuous” is an aspect in which the sipe portion 28 is formed between virtual lines 27 c and 27 c in which the groove edges 27 e and 27 e on both sides of the outer portion 27 are smoothly extended to the third main groove 5 side. This definition is also applied to the case of the second lateral groove 29 and the third lateral groove 32 described later.

  The outer portion 27 and the sipe portion 28 extend in an arc shape. Thereby, the drainage resistance in the groove is ensured to be small, so that the wet performance is improved.

  In the present embodiment, the first sipe 26 has both ends 26 e and 26 i that terminate in the third land portion 11 and are inclined in the same direction as the outer portion 27 of the first lateral groove 25. Such a 1st sipe 26 maintains the tire axial direction rigidity of the 3rd land part 11 highly.

  The inner end 26 i of the first sipe 26 is located on the outer side in the tire axial direction than the inner end 27 i of the outer portion 27. That is, the first sipe 26 does not overlap the sipe portion 28 in the tire axial direction. Such a first sipe 26 opens and closes the groove edges 27e and 27e of the outer side portion 27 of the first lateral groove 25 at the time of grounding while maintaining a large pattern rigidity on the tire equator C side of the third land portion 11. Helps to drain more water.

  In order to suppress an excessive decrease in the tire circumferential rigidity of the third land portion 11, it is desirable that the tire axial length L5 of the first sipe 26 is smaller than the tire axial length L4 of the outer portion 27. The tire axial direction length L5 of the first sipe 26 is more preferably 65% to 85% of the tire axial direction length L4 of the outer portion 27.

  The fourth land portion 12 is provided with a second lateral groove 29 that crosses the fourth land portion 12. The second lateral groove 29 includes an outer portion 30 that extends from the third main groove 5 to the fourth main groove 6 side, and a sipe portion 31 that continues to the outer portion 30 and communicates with the fourth main groove 6. Thereby, also in the 4th land part 12, wet performance and abrasion resistance performance are improved.

  The outer portion 30 and the sipe portion 31 are inclined in the same direction with respect to the tire axial direction. Thereby, the rigidity fall of the 4th land part 12 in the crossing position of the outer side part 30 and the sipe part 31 is suppressed. In the present embodiment, the outer portion 30 and the sipe portion 31 are smoothly continuous.

  The outer portion 30 and the sipe portion 31 extend in an arc shape. Thereby, the drainage resistance in the groove is ensured to be small, so that the wet performance is improved.

  The outer portion 30 of the second lateral groove 29 is smoothly continuous via the sipe portion 28 of the first lateral groove 25 and the first main groove 3. Thereby, the pattern rigidity of the 3rd land part 11 of the 1st horizontal groove 25 vicinity of the sipe part 28 becomes moderately small, and since the opening / closing of the sipe part 28 at the time of grounding becomes large, wet performance improves. “Smoothly continuous” is an aspect in which an imaginary line 28 c obtained by extending the sipe portion 28 of the first lateral groove 25 to the tire equator C side intersects the outer portion 30 of the second lateral groove 29.

  Thus, in the present embodiment, the second land portion 10 to the fourth land portion 12 are not provided with the vertical slot 17. Thereby, the pattern rigidity of the 2nd land part 10 thru | or the 4th land part 12 to which a lateral force acts largely compared with the 1st land part 9 is maintained large. Further, by using a large lateral force, the inner shoulder lug groove 20 of the second land portion 10, the first lateral groove 25 of the third land portion 11, and the second lateral groove 29 of the fourth land portion 12 are connected to the land portions 10 to 10. The water film below 12 is smoothly discharged to the tread ends Ti and To sides. Accordingly, the rigidity balance of the first to fourth land portions 9 to 12 is enhanced, the turning force toward the vehicle outer side and the vehicle inner side can be approached uniformly, and the water film is effectively discharged, The turning performance on the wet road surface is greatly improved while maintaining the stable driving performance on the dry road surface.

  The fifth land portion 13 is provided with a third lateral groove 32 that crosses the fifth land portion 13. The third lateral groove 32 includes an outer portion 33 extending from the fourth main groove 6 and a sipe portion 34 that continues to the outer portion 33 and communicates with the first main groove 3.

  The outer portion 33 and the sipe portion 34 are inclined in the same direction with respect to the tire axial direction. Thereby, the rigidity fall of the 5th land part 13 in the crossing position of the outer side part 33 and the sipe part 34 is suppressed. In the present embodiment, the outer portion 33 and the sipe portion 34 are smoothly continuous.

  The outer portion 33 of the third lateral groove 32 is smoothly continuous via the sipe portion 31 of the second lateral groove 29 and the fourth main groove 6. Thereby, the pattern rigidity of the 4th land part 12 near the sipe part 31 of the 2nd horizontal groove 29 becomes moderately small, and since the opening and closing of the sipe part 31 at the time of grounding becomes large, wet performance improves. “Smoothly continuous” is an aspect in which an imaginary line 31 c obtained by extending the sipe portion 31 of the second lateral groove 29 toward the tire equator C side intersects the outer portion 33 of the third lateral groove 32.

  The fifth land portion 13 is provided with a fifth lug groove 35 extending from the first main groove 3 to the fourth main groove 6 side and terminating in the fifth land portion 13. Such fifth lug grooves 35 enhance the pattern rigidity on both sides in the tire axial direction of the fifth land portion 13 in a well-balanced manner, and make the wear on both sides in the tire axial direction of the fifth land portion 13 closer uniformly.

  As mentioned above, although embodiment of this invention was explained in full detail, it cannot be overemphasized that this invention is not limited to illustrated embodiment, and can be deform | transformed and implemented in a various aspect.

A pneumatic tire for a passenger car of size 215 / 60R17 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1 and tested for wear resistance and wet performance. The main common specifications and test methods for each sample tire are as follows.
Tread contact width TW: 158mm
Groove depth of each main groove: 8.2mm
Maximum groove depth on the outer side of the first lateral groove: 6.6 mm
Groove depth of each outer portion of the second and third transverse grooves: 5.8 mm for both
Groove depth of each sipe part: 4.0 to 5.5 mm
Depth of each sipe: 4.0mm

<Operation stability on dry road surface / turning performance on wet road surface>
Each test tire is mounted on all wheels of a 2400cc front-wheel drive passenger car under the following conditions, and the test driver has a dry asphalt road test course and a wet asphalt road test course with a water depth of 6 mm. Was run. The running characteristics related to steering wheel response, turning performance, traction, grip, and the like at this time were evaluated by the test driver's sensuality. The results are displayed with a score of Example 1 being 100. The larger the value, the better. A numerical 10-point difference is when there is a significant performance change between them, and a 5-point difference is when there is a clear performance change between them. Differences of 3 points or less are differences that are difficult for passengers to notice.
Rim (all wheels): 7.0J × 17
Internal pressure (all wheels): 240 kPa
Table 1 shows the test results.

  As a result of the test, it can be confirmed that the tire of the example is improved in turning performance on the wet road surface by about 10 points while maintaining the steering stability performance on the dry road surface as compared with the tire of the comparative example 1. Moreover, the same tendency as this test result was shown when the tire size was changed.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 1st main groove 4 2nd main groove 9 1st land part 15 1st lug groove 15e Inner end 16 of 1st lug groove 2nd lug groove 16e Inner end 17 of 2nd lug groove Slot 17e Vertical slot both ends Ti tread end

Claims (8)

A pneumatic tire having a tread portion,
The tread portion is provided with a plurality of main grooves extending continuously in the tire circumferential direction,
The main groove includes a first main groove and a second main groove that is adjacent to the first main groove and that is provided outside the first main groove in the tire axial direction,
A first land portion is formed between the first main groove and the second main groove,
In the first land portion,
A first lug groove having an inner end extending from the first main groove and terminating in the first land portion;
A second lug groove extending from the second main groove and having an inner end terminating in the first land portion, and a vertical slot communicating with the second lug groove and having both ends terminating in the first land portion are provided. And
A pneumatic tire characterized in that a tire axial direction length of the second lug groove is 50% or more of a maximum width in the tire axial direction of the first land portion. The tread portion has an asymmetric pattern in which the direction of mounting on the vehicle is specified,
The asymmetric pattern includes an inner tread edge located on the inner side of the vehicle when the tire is attached to the vehicle;
The pneumatic tire according to claim 1, wherein the second main groove is provided on an innermost tread end side.   The pneumatic tire according to claim 1, wherein the first lug groove and the second lug groove are inclined with respect to a tire axial direction.   The pneumatic tire according to claim 3, wherein the first lug groove and the second lug groove are inclined in the same direction. The first lug grooves and the second lug grooves are alternately arranged in the tire circumferential direction,
The pneumatic tire according to any one of claims 1 to 4, wherein both ends of the vertical slot are positioned in the vicinity thereof without communicating with the inner end of the first lug groove adjacent in the tire circumferential direction.   The pneumatic tire according to claim 1, wherein the vertical slot extends along a tire circumferential direction.   The pneumatic tire according to claim 1, wherein a groove depth of the vertical slot is 1 to 2 mm.   The pneumatic tire according to any one of claims 1 to 6, wherein a groove width of the second main groove is the largest among the groove widths of the main grooves.

Images