JP2019073062A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving steering stability on a snow road surface and steering stability on a wet road surface and reducing noise outside the vehicle. SOLUTION: In a pneumatic tire in which a mounting direction with respect to a vehicle is specified, each of an inner shoulder land portion 21 and an outer shoulder land portion 25 has narrow grooves 31 and 35 extending in the tire circumferential direction and a plurality of narrow grooves extending in the tire width direction. The lug grooves 41 and 45 of the book are formed, and the fine ribs 51 and 55 extending in the tire circumferential direction are partitioned between each of the narrow grooves and the corresponding main grooves 11 and 14, and the vehicle is provided in the inner intermediate land portion 22. A plurality of lug grooves 42A that open inward are formed, a plurality of lug grooves 43A that open inward to the inside of the vehicle are formed in the center land portion 23, and a plurality of lug grooves that open to the outside of the vehicle are formed in the outer intermediate land portion 24. 44A is formed, there is no lug groove opening in the main groove 13 on the outer side of the vehicle, and auxiliary sipes 62 to 64 and main sipes 72 to 74 are formed in each of the land portions 22 to 24. [Selection diagram] Fig. 2

Description

  The present invention relates to a pneumatic tire whose mounting direction to a vehicle is specified, and more specifically, it is possible to improve the steering stability on a snowy road surface and the steering stability on a wet road surface and reduce external noise. Relates to a pneumatic tire.

  In a pneumatic tire whose mounting direction to a vehicle is specified, four main grooves extending in the circumferential direction of the tire are formed in the tread portion, and five rows of land portions are defined by these main grooves and located between the main grooves It has been proposed to form in each land portion a plurality of lug grooves that extend in the tire width direction and communicate with the main groove inside the vehicle while terminating in the land portion without communicating with the main groove outside the vehicle (See, for example, Patent Document 1).

  In the pneumatic tire configured as described above, each of the lug grooves formed in the land portion located between the main grooves has a structure in which one end is open to the main groove and the other end is terminated in the land portion, It is expected to exhibit excellent steering stability on wet road surfaces while sufficiently maintaining the rigidity of each land portion. Further, since all of these lug grooves are opened toward the inside of the vehicle, it is expected that pumping noise and pattern noise during traveling will be radiated toward the inside of the vehicle to reduce external noise. However, in recent years, there is a need to further improve the steering stability and noise performance on wet road surfaces. In addition, tires for all seasons are required to exhibit excellent steering stability not only on wet road surfaces but also on snow road surfaces.

International Publication WO2015 / 005194

  An object of the present invention is to provide a pneumatic tire capable of reducing external noise while improving steering stability on a snowy road surface and steering stability on a wet road surface.

According to a first pneumatic tire of the present invention for achieving the above object, there is provided an annular tread portion extending in the circumferential direction of the tire, a pair of side wall portions disposed on both sides of the tread portion, and In a pneumatic tire having a pair of bead portions disposed on the tire radial direction inner side of a sidewall portion and in which a mounting direction with respect to a vehicle is specified,
Four main grooves extending in the circumferential direction of the tire are formed in the tread portion, and five rows of land portions are divided by these main grooves, and the four main grooves are sequentially arranged from the inside to the outside of the vehicle An inner shoulder land portion, an inner intermediate land portion including the first main groove, the second main groove, the third main groove, and the fourth main groove, wherein the land portions of the five rows are sequentially arranged from the vehicle inner side toward the vehicle outer side , Center land, outer middle land and outer shoulder land,
A narrow groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed in each of the inner shoulder land portion and the outer shoulder land portion, and each narrow groove and the corresponding first main groove or Between the fourth main groove and a narrow rib extending in the circumferential direction of the tire,
The inner middle land portion is formed with a plurality of lug grooves having one end opened to the first main groove inside the vehicle and the other end closed in the inner middle land portion, and the center land portion has one end second to the vehicle inner side A plurality of lug grooves are formed in the main groove and the other end is closed in the center land portion, and one end of the outer intermediate land portion is open in the fourth main groove on the vehicle outer side and the other end is in the outer intermediate land portion. And a plurality of lug grooves closed at the end of the vehicle, and there is no lug groove opened in the third main groove outside the vehicle,
Each of the inner intermediate land portion, the center land portion and the outer intermediate land portion includes a plurality of extending from the closed end of the lug groove and communicating with a main groove located on the closed end side of the lug groove. The auxiliary sipe and the main sipe located between the lug grooves adjacent to each other in the tire circumferential direction are formed.

Further, according to a second pneumatic tire of the present invention for achieving the above object, there is provided an annular tread portion extending in the circumferential direction of the tire, and a pair of sidewall portions disposed on both sides of the tread portion. A pneumatic tire having a pair of bead portions disposed on the inner side in the tire radial direction of the side wall portions, and in which the mounting direction to the vehicle is specified,
Four main grooves extending in the circumferential direction of the tire are formed in the tread portion, and five rows of land portions are divided by these main grooves, and the four main grooves are sequentially arranged from the inside to the outside of the vehicle An inner shoulder land portion, an inner intermediate land portion including the first main groove, the second main groove, the third main groove, and the fourth main groove, wherein the land portions of the five rows are sequentially arranged from the vehicle inner side toward the vehicle outer side , Center land, outer middle land and outer shoulder land,
A narrow groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed in each of the inner shoulder land portion and the outer shoulder land portion, and each narrow groove and the corresponding first main groove or Between the fourth main groove and a narrow rib extending in the circumferential direction of the tire,
The inner middle land portion is formed with a plurality of lug grooves, one end of which opens into the first main groove inside the vehicle and the other end is closed in the inner middle land portion, and the center land portion has a third end outside the vehicle A plurality of lug grooves are formed in the main groove and the other end is closed in the center land portion, and one end of the outer intermediate land portion is open in the fourth main groove on the vehicle outer side and the other end is in the outer intermediate land portion. And a plurality of lug grooves closed at the end of the vehicle, and there is no lug groove opened in the second main groove inside the vehicle,
Each of the inner intermediate land portion, the center land portion and the outer intermediate land portion includes a plurality of extending from the closed end of the lug groove and communicating with a main groove located on the closed end side of the lug groove. The auxiliary sipe and the main sipe located between the lug grooves adjacent to each other in the tire circumferential direction are formed.

  The inventors of the present invention conducted intensive studies on the arrangement of lug grooves closed at one end of a pneumatic tire whose mounting direction to a vehicle is specified, and as a result all of these lug grooves were opened toward the inside of the vehicle When the pattern noise generated due to the lag groove is reflected in the tire house and emitted to the outside of the vehicle, the radiation noise is added to become a factor of increase of the noise, and further travel on the wet road surface It has been found that the water released from the lug grooves remains in the tire house and causes deterioration of the steering stability on a wet road surface.

  That is, in the first pneumatic tire, the lug grooves formed in the inner intermediate land portion and the center land portion are opened toward the vehicle inner side, and the lug grooves formed in the outer intermediate land portion are opened toward the vehicle outer side Therefore, the noise emitted from these lug grooves is dispersed to the inside and the outside of the vehicle to reduce the external noise, and the drainage from the lug grooves is dispersed to the inside and the outside of the vehicle when traveling on a wet road surface. Steering stability at In each of the inner intermediate land portion, the center land portion and the outer intermediate land portion, a plurality of auxiliary sipes which extend from the closed end of the lug groove and communicate with the main groove located on the closed end side of the lug groove And the main sipe located between the lug grooves adjacent to each other in the tire circumferential direction, the main sipe and the auxiliary sipe cooperate with the lug grooves to exhibit an edge effect, which is excellent on a snow road surface The steering stability can be exhibited. This makes it possible to improve the steering stability on a snowy road surface and the steering stability on a wet road surface, and reduce external noise. In particular, the first pneumatic tire is advantageous in improving steering stability on a snowy road surface and reducing external noise.

  Further, in the second pneumatic tire, the lug grooves formed in the inner intermediate land portion are opened toward the vehicle inner side, and the lug grooves formed in the center land portion and the outer intermediate land portion are opened toward the vehicle outer side. Therefore, the noise emitted from these lug grooves is dispersed to the inside and the outside of the vehicle to reduce the external noise, and the drainage from the lug grooves is dispersed to the inside and the outside of the vehicle when traveling on a wet road surface. Steering stability at In each of the inner intermediate land portion, the center land portion and the outer intermediate land portion, a plurality of auxiliary sipes which extend from the closed end of the lug groove and communicate with the main groove located on the closed end side of the lug groove And the main sipe located between the lug grooves adjacent to each other in the tire circumferential direction, the main sipe and the auxiliary sipe cooperate with the lug grooves to exhibit an edge effect, which is excellent on a snow road surface The steering stability can be exhibited. This makes it possible to improve the steering stability on a snowy road surface and the steering stability on a wet road surface, and reduce external noise. In particular, the second pneumatic tire is advantageous in improving steering stability on a snowy road surface and improving steering stability on a wet road surface.

  In any of the structures, narrow grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed in each of the inner shoulder land portion and the outer shoulder land portion. The narrow ribs extending in the circumferential direction of the tire are defined between the main groove and the fourth main groove, but these ensure the rigidity of the inboard shoulder land and the outboard shoulder land, while operating on a wet road surface It is effective in improving stability.

  In the present invention, the ratio L3 / W3 of the length L3 of the lug groove formed in the outer intermediate land portion to the width W3 of the outer intermediate land portion is preferably 0.1 or more and 0.8 or less. The ratio L2 / W2 of the length L2 of the lug grooves formed in the center land portion to the width W2 of the center land portion is preferably 0.1 or more and 0.8 or less. The ratio L1 / W1 of the length L1 of the lug groove formed in the inner middle land portion to the width W1 of the inner middle land portion is preferably 0.1 or more and 0.8 or less. As a result, the steering stability on the wet road surface can be improved and the external noise can be reduced while maintaining the steering stability on the snow road surface well.

  It is preferable that inclination angle (theta) 3 with respect to the tire peripheral direction of the lug groove formed in the outer side middle land part is 30 degrees or more and 85 degrees or less. The inclination angle θ2 of the lug grooves formed in the center land portion with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. It is preferable that inclination angle (theta) 1 with respect to the tire peripheral direction of the lug groove formed in the inner side middle land part is 30 degrees or more and 85 degrees or less. As a result, the steering stability on the wet road surface can be improved and the external noise can be reduced while maintaining the steering stability on the snow road surface well.

  A lug groove formed on the inner shoulder land portion terminates in the narrow rib across the narrow groove, and the ratio of the projection length Li of the lug groove to the narrow rib to the width Wi of the narrow rib in the inner shoulder land portion Li / Wi Is preferably 0.2 or more and 0.8 or less. Similarly, the lug groove formed on the outer shoulder land portion terminates in the narrow rib across the narrow groove, and the ratio of the protrusion length Lo of the lug groove to the narrow rib to the width Wo of the narrow rib in the outer shoulder land portion It is preferable that Lo / Wo is 0.2 or more and 0.8 or less. As a result, the steering stability on the wet road surface can be improved and the external noise can be reduced while maintaining the steering stability on the snow road surface well.

  Further, it is preferable that the lug grooves formed on the inner middle land portion, the center land portion and the outer middle land portion have a linear shape. Since the lug groove has a linear shape, the block portion subdivided by the lug groove falls in the same direction during driving and braking, thereby increasing the snow pillar shear force and improving the steering stability on the snow road surface. Can.

  It is preferable that both ends of the main sipe communicate with main grooves located on both sides of the main sipe. When the both ends of the main sipe communicate with the main groove, the land portion is easily deformed, so that the steering stability on a snow road surface can be improved.

  It is preferable that the main sipe and the auxiliary sipe have a bent shape in at least one of the inner middle land part, the center land part and the outer middle land part. When the main sipe and the auxiliary sipe have a bent shape, the edge component acts in many directions, so that the steering stability on a snow road surface can be improved.

  In the present invention, the main sipe formed on the outer shoulder land portion is formed with the main sipe located between the lug grooves adjacent in the tire circumferential direction on each of the inner shoulder land portion and the outer shoulder land portion. Can be in communication with the fourth main groove, and the main sipe formed in the inner shoulder land portion can adopt a structure in which it does not communicate with the first main groove. In this case, steering stability on a snow road surface can be effectively improved because the main sipe of the outer shoulder land portion to which a large amount of load is applied at the time of turning is in communication with the fourth main groove.

  In the present invention, the main sipe located between the lug grooves adjacent to each other in the tire circumferential direction is formed in each of the inner shoulder land portion and the outer shoulder land portion, and the main sipe formed in the inner shoulder land portion The sipe is in communication with the first main groove, and the main sipe formed in the outer shoulder land portion can adopt a structure in which it does not communicate with the fourth main groove. In this case, since the main sipe of the outer shoulder land portion to which a large load is applied during turning does not communicate with the fourth main groove, the adhesion frictional force increases with the increase of the contact area, and the steering stability on wet road surface It can be improved effectively.

  In the present invention, there is an auxiliary sipe connecting the closed end of the lug groove formed in the inner shoulder land portion and the first main groove, and the closed end of the lug groove formed in the outer shoulder land portion It is possible to adopt a structure in which there is no auxiliary sipe connecting the fourth main groove and the fourth main groove. In this case, the absence of the auxiliary sipe connecting the closed end of the lug groove formed on the outer shoulder land portion to the fourth main groove reduces external noise, and the closed end of the lug groove formed on the inner shoulder land portion The steering stability on a snow road surface can be improved by providing an auxiliary sipe connecting the first main groove and the second main groove.

  Further, in the present invention, there is an auxiliary sipe connecting the closed end of the lug groove formed in the outer shoulder land portion and the fourth main groove, and the closure of the lug groove formed in the inner shoulder land portion A structure may be employed in which there is no auxiliary sipe connecting the end and the first main groove. In this case, by providing the auxiliary sipe connecting the closed end of the lug groove formed on the outer shoulder land portion and the fourth main groove, drainage performance can be improved and steering stability on a wet road surface can be improved. .

1 is a meridional cross-sectional view showing a pneumatic tire according to a first embodiment of the present invention. It is an expanded view which shows the tread pattern of the pneumatic tire of FIG. It is a top view which expands and shows the tread pattern of FIG. It is a meridional sectional view showing a pneumatic tire concerning a 2nd embodiment of the present invention. It is an expanded view which shows the tread pattern of the pneumatic tire of FIG. It is a top view which expands and shows the tread pattern of FIG.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the attached drawings. 1 to 3 show a pneumatic tire according to a first embodiment of the present invention. The pneumatic tire is a tire in which the mounting direction of the front and back of the tire when the vehicle is mounted is designated. In FIGS. 1 to 3, IN is the inside of the vehicle when the vehicle is mounted, and OUT is the outside of the vehicle when the vehicle is mounted.

  As shown in FIG. 1, the pneumatic tire according to the present embodiment includes a tread portion 1 extending in the circumferential direction of the tire to form an annular shape, and a pair of sidewall portions 2 and 2 disposed on both sides of the tread portion 1. And a pair of bead portions 3 and 3 disposed on the inner side in the tire radial direction of the side wall portions 2.

  A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside to the outside around the bead cores 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is disposed on the outer periphery of the bead core 5.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. The belt layers 7 include a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are disposed so as to cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set, for example, in the range of 10 ° to 40 °. As a reinforcing cord of the belt layer 7, a steel cord is preferably used. At least one belt cover layer 8 formed by arranging reinforcing cords at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer circumferential side of the belt layer 7 for the purpose of improving high-speed durability. There is. As a reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In addition, although the tire internal structure mentioned above shows the typical example in a pneumatic tire, it is not limited to this.

  As shown in FIG. 2, in the tread portion 1, four main grooves 10 extending in the tire circumferential direction are formed, and five rows of land portions 20 are divided by the four main grooves 10. The main groove 10 is a groove that carries a main drainage function, and the groove width is set to a range of 6.0 mm to 12.0 mm, and the groove depth is set to a range of 6.0 mm to 10.0 mm There is. The main groove 10 includes a first main groove 11, a second main groove 12, a third main groove 13 and a fourth main groove 14 sequentially arranged from the vehicle inner side toward the vehicle outer side, and the land portion 20 of five rows is a vehicle An inner shoulder land portion 21, an inner intermediate land portion 22, a center land portion 23, an outer intermediate land portion 24 and an outer shoulder land portion 25 are sequentially arranged from the inside toward the vehicle outer side.

  The inner shoulder land portion 21 is formed with a single narrow groove 31 extending in the tire circumferential direction, and a plurality of lug grooves 41 extending in the tire width direction are formed at intervals in the tire circumferential direction. A thin rib 51 extending in the tire circumferential direction is defined between 31 and the first main groove 11. On the other hand, one narrow groove 35 extending in the tire circumferential direction is formed in the outer shoulder land portion 25 and a plurality of lug grooves 45 extending in the tire width direction are formed at intervals in the tire circumferential direction. A narrow rib 55 extending in the tire circumferential direction is defined between the narrow groove 35 and the fourth main groove 14. The groove width of each of the narrow grooves 31 and 35 is set in the range of 0.5 mm to 3.0 mm, and the groove depth is set in the range of 2.0 mm to 5.0 mm. Further, each of the thin ribs 51 and 55 is continuous in the tire circumferential direction without being divided by the lug grooves 41 and 45.

  The inner intermediate land portion 22 is formed with a plurality of lug grooves 42A, one end of which is open to the first main groove 11 inside the vehicle and the other end of which is closed in the inner intermediate land portion 22, spaced in the tire circumferential direction. It is done. The center land portion 23 is formed with a plurality of lug grooves 43A spaced at intervals in the tire circumferential direction, with one end opened to the second main groove 12 inside the vehicle and the other end closed in the center land portion 23 There is. A plurality of lug grooves 44A, one end of which is open to the fourth main groove 14 on the vehicle outer side and the other end of which is closed in the outer intermediate land portion 24, are formed in the outer intermediate land portion 24 at intervals in the tire circumferential direction. It is done. Further, there is no lug groove opened to the third main groove 13 on the vehicle outer side, and the edge portions on the third land 13 side of the center land portion 23 and the outer intermediate land portion 24 are continuous without being divided by the lug grooves. Extended.

  Furthermore, in the inner intermediate land portion 22, a plurality of auxiliary sipes 62 which extend from the closed end of the lug groove 42A and communicate with the second main groove 12 located on the closed end side of the lug groove 42A; A main sipe 72 is formed between the lug grooves 42A adjacent in the direction. The auxiliary sipes 62 and the main sipes 72 extend in the tire width direction, and are alternately arranged along the tire circumferential direction. The center land portion 23 has a plurality of auxiliary sipes 63 extending from the closed end of the lug groove 43A and communicating with the third main groove 13 located on the closed end side of the lug groove 43A, and adjacent to the tire circumferential direction A main sipe 73 is formed between the mating lug grooves 43A. The auxiliary sipes 63 and the main sipes 73 extend in the tire width direction, and are alternately arranged along the tire circumferential direction. In the outer intermediate land portion 24, a plurality of auxiliary sipes 64 extending from the closed end of the lug groove 44A and communicating with the third main groove 13 located on the closed end side of the lug groove 44A, and in the tire circumferential direction A main sipe 74 located between the adjacent lug grooves 44A is formed. The auxiliary sipes 64 and the main sipes 74 extend in the tire width direction, and are alternately arranged along the tire circumferential direction.

  In the pneumatic tire according to the first embodiment described above, the lug grooves 42A and 43A formed in the inner intermediate land portion 22 and the center land portion 23 open toward the vehicle inner side, and the lugs formed in the outer intermediate land portion 24 The grooves 44A open toward the outside of the vehicle, so the noise emitted from the lug grooves 42A to 44A is dispersed to the inside and the outside of the vehicle to reduce external noise. In addition, when the wet road surface travels, the drainage from the lug grooves 42A to 44A is dispersed to the vehicle inner side and the vehicle outer side, and the steering stability on the wet road surface is improved. In each of the inner intermediate land portion 22, the center land portion 23, and the outer intermediate land portion 24, a main extending from the closed end of the lug grooves 42A to 44A and located on the closed end side of the lug grooves 42A to 44A. Since a plurality of auxiliary sipes 62 to 64 communicating with the grooves 10 and main sipes 72 to 74 located between the lug grooves 42A to 44A adjacent in the tire circumferential direction are formed, these main sipes 72 to 72 are formed. 74 and the auxiliary sipes 62 to 64 cooperate with the lug grooves 42A to 44A to exert an edge effect, and can exhibit excellent steering stability on a snow road surface. This makes it possible to improve the steering stability on a snowy road surface and the steering stability on a wet road surface, and reduce external noise. In particular, according to the above-described structure, it is possible to effectively improve the steering stability on a snowy road surface and to effectively reduce the external noise.

  Here, narrow grooves 31 and 35 extending in the tire circumferential direction and a plurality of lug grooves 41 and 45 extending in the tire width direction are formed in each of the inner shoulder land portion 21 and the outer shoulder land portion 25. The steering stability on a wet road surface can be favorably secured. Further, since the narrow ribs 51 and 55 extending in the tire circumferential direction are divided between the narrow grooves 31 and 35 and the corresponding first main groove 11 or the fourth main groove 14, these thin ribs 51 , 55 secure the rigidity of the inboard shoulder land portion 21 and the outboard shoulder land portion 25 and contribute to the reduction of external noise.

  In the pneumatic tire, as shown in FIG. 3, the ratio L3 / W3 of the length L3 of the lug groove 44A to the width W3 of the outer intermediate land portion 24 is preferably 0.1 or more and 0.8 or less. If the ratio L3 / W3 is smaller than 0.1, steering stability on a snow road surface can not be effectively improved. Conversely, if the ratio L3 / W3 is greater than 0.8, in addition to the improvement effect of the steering stability on a wet road surface decreasing with the decrease of the adhesion frictional force, the generation of the pumping sound is effective To reduce the effect of reducing external noise. The ratio L3 / W3 of the lug groove 44A is preferably 0.2 or more and 0.5 or less.

  The ratio L2 / W2 of the length L2 of the lug groove 43A to the width W2 of the center land portion 23 is preferably 0.1 or more and 0.8 or less. If the ratio L2 / W2 is smaller than 0.1, steering stability on a snow road surface can not be effectively improved. Conversely, if the ratio L2 / W2 is greater than 0.8, in addition to the improvement effect of steering stability on a wet road surface decreasing with the decrease of the adhesion friction force, the generation of the pumping sound is effective To reduce the effect of reducing external noise. The ratio L2 / W2 of the lug groove 43A is preferably 0.2 or more and 0.5 or less.

  The ratio L1 / W1 of the length L1 of the lug groove 42A to the width W1 of the inner intermediate land portion 22 is preferably 0.1 or more and 0.8 or less. If the ratio L1 / W1 is smaller than 0.1, steering stability on a snow road surface can not be effectively improved. Conversely, if the ratio L1 / W1 is greater than 0.8, in addition to the effect of improving the steering stability on a wet road surface decreasing with the decrease in the adhesion frictional force, the generation of the pumping sound is effective. To reduce the effect of reducing external noise. The ratio L1 / W1 of the lug groove 42A is desirably 0.5 or more and 0.8 or less.

  In the above pneumatic tire, when L1 / W1 = X1, L2 / W2 = X2, and L3 / W3 = X3, it is preferable to satisfy the relationship of X1> X2 and X1> X3, and in particular, X1 / X2 = It is preferable to satisfy the relationship of 1.5 to 2.5 and X1 / X3 = 1.5 to 2.5. As a result, the difference in rigidity of the land portions 22 to 24 becomes large, and a difference occurs in the amount of deformation generated in the main grooves 11 to 14 when grounded, thereby dispersing the frequency of air column resonance sound (stationary wave) Can be reduced.

  In the pneumatic tire, as shown in FIG. 3, the inclination angle θ3 of the lug grooves 44A formed in the outer intermediate land portion 24 with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. If the inclination angle θ3 of the lug grooves 44A is smaller than 30 °, it is impossible to obtain sufficient snow column shear force. Conversely, when the inclination angle θ3 of the lug groove 44A is larger than 85 °, the rigidity of the outer intermediate land portion 24 is increased in addition to the decrease in drainage performance, and the outer intermediate land portion when the contact pressure acts. Since the deformation of 24 is reduced, the generation of stationary waves can not be sufficiently suppressed, and the generation of external noise can not be effectively suppressed. The inclination angle θ3 of the lug groove 44A is desirably 45 ° or more and 75 ° or less.

  The inclination angle θ2 of the lug grooves 43A formed in the center land portion 23 with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. When the inclination angle θ2 of the lug grooves 43A is smaller than 30 °, it is not possible to obtain sufficient snow column shear force. Conversely, when the inclination angle θ2 of the lug groove 43A is larger than 85 °, the rigidity of the center land portion 23 is increased in addition to the decrease in drainage performance, and the center land portion 23 when the contact pressure acts. Since the deformation is small, the generation of the stationary wave can not be sufficiently suppressed, and the generation of the external noise can not be effectively suppressed. The inclination angle θ2 of the lug groove 43A is desirably 45 ° or more and 75 ° or less.

  The inclination angle θ1 of the lug grooves 42A formed in the inner intermediate land portion 22 with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. When the inclination angle θ1 of the lug grooves 42A is smaller than 30 °, it is impossible to obtain sufficient snow column shear force. Conversely, when the inclination angle θ1 of the lug groove 42A is larger than 85 °, the rigidity of the inner intermediate land portion 22 is increased in addition to the decrease in drainage performance, and the inner intermediate land portion when the contact pressure acts. Since the deformation of 22 is reduced, the generation of stationary waves can not be sufficiently suppressed, and the generation of external noise can not be effectively suppressed. The inclination angle θ1 of the lug groove 42A is desirably 45 ° or more and 75 ° or less.

  As for the inclination angles θ1 to θ3 of the lug grooves 42A to 44A, in each of the lug grooves 42A to 44A, a straight line passing through the groove width center position at the opening end and the groove width center position at the closing end is relative to the tire circumferential direction. This is the angle that is made.

  In the pneumatic tire, the lug groove 41 formed in the inner shoulder land portion 21 crosses the narrow groove 31 and terminates in the narrow rib 51, and the lug groove 41 with respect to the width Wi of the narrow rib 51 in the inner shoulder land portion 21 The ratio Li / Wi of the protruding length Li to the thin rib 51 is preferably 0.2 or more and 0.8 or less. If the ratio Li / Wi is less than 0.2, steering stability on a snow road surface can not be effectively improved. Conversely, if the ratio Li / Wi is greater than 0.8, the effect of improving steering stability on a wet road surface decreases with the decrease in adhesion friction, and the effect of reducing external noise also decreases. Do. The ratio Li / Wi is preferably 0.3 or more and 0.7 or less.

  In the pneumatic tire, the lug groove 45 formed in the outer shoulder land portion 25 crosses the narrow groove 35 and terminates in the narrow rib 55, and the lug groove 45 of the width Wo of the narrow rib 55 in the outer shoulder land portion 25 The ratio Lo / Wo of the protruding length Lo to the thin rib 55 is preferably 0.2 or more and 0.8 or less. If the ratio Lo / Wo is less than 0.2, the steering stability on a snowy road surface can not be effectively improved. On the other hand, when the ratio Lo / Wo is larger than 0.8, the effect of improving the steering stability on a wet road surface decreases with the decrease of the adhesion friction force, and the effect of reducing the external noise also decreases. Do. The ratio Lo / Wo is desirably 0.3 or more and 0.7 or less.

  In the pneumatic tire, it is preferable that the lug grooves 42A, 43A, 44A formed in the inner intermediate land portion 22, the center land portion 23, and the outer intermediate land portion 24 have a linear shape. When the lug grooves 42A to 44A have a linear shape, the block portion subdivided by the lug grooves 42A to 44A falls in the same direction during driving and braking, so that the snow post shear force increases and steering stability on a snow road surface I can improve the sex.

  In the pneumatic tire, it is preferable that both ends of the main sipes 72 to 74 communicate with the main grooves 11 to 14 located on both sides of each of the main sipes 72 to 74, respectively. Since the lands 22 to 24 are easily deformed when both ends of the main sipes 72 to 74 communicate with the main grooves 11 to 14, the steering stability on a snow road surface can be improved.

  In particular, at least one of the inner intermediate land portion 22, the center land portion 23, and the outer intermediate land portion 24 (the outer intermediate land portion 24 in FIG. 3), the main sipes 72 to 74 (main sipes 74 in FIG. 3) and the auxiliary sipes 62 to 64 (in FIG. 3, the auxiliary sipe 64) may have a bent shape. With the bent shapes of the main sipes 72 to 74 and the auxiliary sipes 62 to 64, the edge component acts in many directions, so that the steering stability on a snow road surface can be improved.

  In the pneumatic tire, the inner shoulder land portion 21 is formed with a plurality of main sipes 71 located between the lug grooves 41 adjacent in the tire circumferential direction, and the outer shoulder land portion 25 is provided with a tire A plurality of main sipes 75 positioned between the circumferentially adjacent lug grooves 45 are formed. The main sipe 75 formed in the outer shoulder land portion 25 communicates with the fourth main groove 14, but the main sipe 71 formed in the inner shoulder land portion 21 communicates with the first main groove 11. Not. In this case, since the main sipe 75 of the outer shoulder land portion 25 to which a large amount of load is applied at the time of turning is in communication with the fourth main groove 14, steering stability on a snow road surface can be effectively improved.

  In the pneumatic tire described above, an auxiliary sipe 61 is provided between the closed end of the lug groove 41 formed in the inner shoulder land portion 21 and the first main groove 11 to connect the both, and is formed in the outer shoulder land portion 25 There is no auxiliary sipe (corresponding to the auxiliary sipe 61) connecting the closed end of the lug groove 45 and the fourth main groove 14 to each other. In this case, the absence of the auxiliary sipe connecting the closed end of the lug groove 45 formed on the outer shoulder land portion 25 and the fourth main groove 14 reduces external noise, and the lug formed on the inner shoulder land portion 21 By providing the auxiliary sipe 61 connecting the closed end of the groove 41 and the first main groove 11, the steering stability on a snow road surface can be improved.

  4 to 6 show a pneumatic tire according to a second embodiment of the present invention. The pneumatic tire is a tire in which the mounting direction of the front and back of the tire when the vehicle is mounted is designated. 4 to 6, IN is the inside of the vehicle when the vehicle is mounted, and OUT is the outside of the vehicle when the vehicle is mounted. The second embodiment differs from the first embodiment in the structure of the lug grooves (42 B, 43 B, 44 B) formed in the inner intermediate land portion 22, the center land portion 23 and the outer intermediate land portion 24. In FIGS. 4 to 6, the same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and the detailed description of those portions is omitted.

  As shown in FIGS. 4 and 5, one narrow groove 31 extending in the tire circumferential direction is formed in the inner shoulder land portion 21, and a plurality of lug grooves 41 extending in the tire width direction are formed in the tire circumferential direction. Between the narrow groove 31 and the first main groove 11, a narrow rib 51 extending in the circumferential direction of the tire is partitioned. On the other hand, one narrow groove 35 extending in the tire circumferential direction is formed in the outer shoulder land portion 25 and a plurality of lug grooves 45 extending in the tire width direction are formed at intervals in the tire circumferential direction. A narrow rib 55 extending in the tire circumferential direction is defined between the narrow groove 35 and the fourth main groove 14. Further, each of the thin ribs 51 and 55 is continuous in the tire circumferential direction without being divided by the lug grooves 41 and 45.

  The inner intermediate land portion 22 is formed with a plurality of lug grooves 42B, one end of which opens to the first main groove 11 inside the vehicle and the other end of which is closed in the inner intermediate land portion 22, spaced in the tire circumferential direction It is done. The center land portion 23 is formed with a plurality of lug grooves 43B spaced at intervals in the tire circumferential direction, with one end opened to the third main groove 13 outside the vehicle and the other end closed in the center land portion 23 There is. The outer intermediate land portion 24 is formed with a plurality of lug grooves 44B having one end opened in the fourth main groove 14 on the vehicle outer side and the other end closed in the outer intermediate land portion 24 at intervals in the tire circumferential direction It is done. Further, there is no lug groove opened in the second main groove 12 inside the vehicle, and the edge portions on the inner side middle land portion 22 and the center land portion 23 on the second main groove 12 side are continuous without being divided by the lug grooves. Extended.

  Furthermore, in the inner intermediate land portion 22, a plurality of auxiliary sipes 62 extending from the closed end of the lug groove 42B and in communication with the second main groove 12 positioned on the closed end side of the lug groove 42B; Main sipe 72 located between mutually adjacent lug grooves 42B in the direction is formed. The auxiliary sipes 62 and the main sipes 72 extend in the tire width direction, and are alternately arranged along the tire circumferential direction. In the center land portion 23, a plurality of auxiliary sipes 63 extending from the closed end of the lug groove 43B and communicating with the second main groove 12 located on the closed end side of the lug groove 43B, and adjacent to the tire circumferential direction A main sipe 73 is formed between the mating lug grooves 43B. The auxiliary sipes 63 and the main sipes 73 extend in the tire width direction, and are alternately arranged along the tire circumferential direction. In the outer intermediate land portion 24, a plurality of auxiliary sipes 64 extending from the closed end of the lug groove 44B and communicating with the third main groove 13 located on the closed end side of the lug groove 44B, and in the tire circumferential direction A main sipe 74 located between the adjacent lug grooves 44B is formed. The auxiliary sipes 64 and the main sipes 74 extend in the tire width direction, and are alternately arranged along the tire circumferential direction.

  In the pneumatic tire according to the second embodiment described above, the lug grooves 42B formed in the inner intermediate land portion 22 open toward the vehicle inner side, and the lug grooves 43B formed in the center land portion 23 and the outer intermediate land portion 24. , 44B open toward the outside of the vehicle, so the noise emitted from these lug grooves 42B to 44B is dispersed to the inside and the outside of the vehicle to reduce external noise. Moreover, when traveling on a wet road surface, the drainage from the lug grooves 42B to 44B is dispersed to the inside and the outside of the vehicle, and the steering stability on the wet road surface is improved. In each of the inner intermediate land portion 22, the center land portion 23, and the outer intermediate land portion 24, a main extending from the closed end of the lug grooves 42A to 44A and located on the closed end side of the lug grooves 42A to 44A. Since a plurality of auxiliary sipes 62 to 64 communicating with the grooves 10 and main sipes 72 to 74 located between the lug grooves 42A to 44A adjacent in the tire circumferential direction are formed, these main sipes 72 to 72 are formed. 74 and the auxiliary sipes 62 to 64 cooperate with the lug grooves 42A to 44A to exert an edge effect, and can exhibit excellent steering stability on a snow road surface. This makes it possible to improve the steering stability on a snowy road surface and the steering stability on a wet road surface, and reduce external noise. In particular, according to the above-described structure, steering stability on a snow road surface can be effectively improved, and steering stability on a wet road surface can be effectively improved.

  Here, narrow grooves 31 and 35 extending in the tire circumferential direction and a plurality of lug grooves 41 and 45 extending in the tire width direction are formed in each of the inner shoulder land portion 21 and the outer shoulder land portion 25. The steering stability on a wet road surface can be favorably secured. Further, since the narrow ribs 51 and 55 extending in the tire circumferential direction are divided between the narrow grooves 31 and 35 and the corresponding first main groove 11 or the fourth main groove 14, these thin ribs 51 , 55 secure the rigidity of the inboard shoulder land portion 21 and the outboard shoulder land portion 25 and contribute to the reduction of external noise.

  In the pneumatic tire, as shown in FIG. 6, the ratio L3 / W3 of the length L3 of the lug groove 44B to the width W3 of the outer intermediate land portion 24 is preferably 0.1 or more and 0.8 or less. If the ratio L3 / W3 is smaller than 0.1, steering stability on a snow road surface can not be effectively improved. Conversely, when the ratio L3 / W3 is larger than 0.8, the improvement effect of the steering stability on a wet road surface decreases with the decrease of the adhesion friction force in addition to the reduction effect of the external noise Do. The ratio L3 / W3 of the lug groove 44B is desirably 0.5 or more and 0.8 or less.

  The ratio L2 / W2 of the length L2 of the lug groove 43B to the width W2 of the center land portion 23 is preferably 0.1 or more and 0.8 or less. If the ratio L2 / W2 is smaller than 0.1, steering stability on a snow road surface can not be effectively improved. On the other hand, when the ratio L2 / W2 is larger than 0.8, the improvement effect of the steering stability on the wet road surface decreases with the decrease of the adhesion friction force in addition to the reduction effect of the outside noise Do. The ratio L2 / W2 of the lug groove 43B is preferably 0.2 or more and 0.5 or less.

  The ratio L1 / W1 of the length L1 of the lug groove 42B to the width W1 of the inner intermediate land portion 22 is preferably 0.1 or more and 0.8 or less. If the ratio L1 / W1 is smaller than 0.1, steering stability on a snow road surface can not be effectively improved. On the other hand, when the ratio L1 / W1 is larger than 0.8, the improvement effect of the steering stability on the wet road surface decreases with the decrease of the adhesion friction force in addition to the reduction effect of the external noise Do. The ratio L1 / W1 of the lug groove 42B is desirably 0.2 or more and 0.5 or less.

  In the pneumatic tire, when L1 / W1 = X1, L2 / W2 = X2, and L3 / W3 = X3, it is preferable to satisfy the relationship of X3> X1 and X3> X2, and in particular, X3> X1 = It is preferable to satisfy the relationship of 1.5 to 2.5, X3> X2 = 1.5 to 2.5. As a result, the difference in rigidity of the land portions 22 to 24 becomes large, and a difference occurs in the amount of deformation generated in the main grooves 11 to 14 when grounded, so that the frequency of air column resonance sound (stationary wave) is dispersed, and external noise is effective. Can be reduced.

  In the pneumatic tire, as shown in FIG. 6, the inclination angle θ3 of the lug grooves 44B formed in the outer intermediate land portion 24 with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. If the inclination angle θ3 of the lug grooves 44B is smaller than 30 °, it is not possible to obtain sufficient snow column shear force. Conversely, when the inclination angle θ3 of the lug groove 44B is larger than 85 °, the rigidity of the outer intermediate land portion 24 is increased in addition to the decrease in drainage performance, and the outer intermediate land portion when the contact pressure acts. Since the deformation of 24 is reduced, the generation of stationary waves can not be sufficiently suppressed, and the generation of external noise can not be effectively suppressed. The inclination angle θ3 of the lug groove 44B is desirably 45 ° or more and 75 ° or less.

  The inclination angle θ2 of the lug grooves 43B formed in the center land portion 23 with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. If the inclination angle θ2 of the lug grooves 43B is smaller than 30 °, it is impossible to obtain sufficient snow column shear force. Conversely, when the inclination angle θ2 of the lug groove 43B is larger than 85 °, the rigidity of the center land portion 23 is increased in addition to the decrease in drainage performance, and the center land portion 23 when the contact pressure is applied. Since the deformation is small, the generation of the stationary wave can not be sufficiently suppressed, and the generation of the external noise can not be effectively suppressed. The inclination angle θ2 of the lug groove 43B is desirably 45 ° or more and 75 ° or less.

  The inclination angle θ1 of the lug grooves 42B formed in the inner intermediate land portion 22 with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. If the inclination angle θ1 of the lug grooves 42B is smaller than 30 °, it is impossible to obtain sufficient snow column shear force. Conversely, when the inclination angle θ1 of the lug groove 42B is larger than 85 °, the rigidity of the center land portion 23 is increased in addition to the decrease in drainage performance, and the center land portion 23 when the contact pressure acts. Since the deformation is small, the generation of the stationary wave can not be sufficiently suppressed, and the generation of the external noise can not be effectively suppressed. The inclination angle θ1 of the lug groove 42B is desirably 45 ° or more and 75 ° or less.

  As for the inclination angles θ1 to θ3 of the lug grooves 42B to 44B, in each of the lug grooves 42B to 44B, a straight line passing through the groove width center position at the opening end and the groove width center position at the closing end is relative to the tire circumferential direction. This is the angle that is made.

  In the pneumatic tire, the lug groove 41 formed in the inner shoulder land portion 21 crosses the narrow groove 31 and terminates in the narrow rib 51, and the lug groove 41 with respect to the width Wi of the narrow rib 51 in the inner shoulder land portion 21 The ratio Li / Wi of the protruding length Li to the thin rib 51 is preferably 0.2 or more and 0.8 or less. If the ratio Li / Wi is less than 0.2, steering stability on a snow road surface can not be effectively improved. Conversely, if the ratio Li / Wi is greater than 0.8, the effect of improving steering stability on a wet road surface decreases with the decrease in adhesion friction, and the effect of reducing external noise also decreases. Do. The ratio Li / Wi is preferably 0.3 or more and 0.7 or less.

  In the pneumatic tire, the lug groove 45 formed in the outer shoulder land portion 25 crosses the narrow groove 35 and terminates in the narrow rib 55, and the lug groove 45 of the width Wo of the narrow rib 55 in the outer shoulder land portion 25 The ratio Lo / Wo of the protruding length Lo to the thin rib 55 is preferably 0.2 or more and 0.8 or less. If the ratio Lo / Wo is less than 0.2, the steering stability on a snowy road surface can not be effectively improved. On the other hand, when the ratio Lo / Wo is larger than 0.8, the effect of improving the steering stability on a wet road surface decreases with the decrease of the adhesion friction force, and the effect of reducing the external noise also decreases. Do. The ratio Lo / Wo is desirably 0.3 or more and 0.7 or less.

  In the pneumatic tire, it is preferable that the lug grooves 42B, 43B, 44B formed in the inner intermediate land portion 22, the center land portion 23, and the outer intermediate land portion 24 have a linear shape. When the lug grooves 42B to 44B have a linear shape, the block portion subdivided by the lug grooves 42A to 44A falls in the same direction during driving and braking, so the snow post shear force increases and steering stability on a snow road surface I can improve the sex.

  In the pneumatic tire, it is preferable that both ends of the main sipes 72 to 74 communicate with the main grooves 11 to 14 located on both sides of each of the main sipes 72 to 74, respectively. Since the lands 22 to 24 are easily deformed when both ends of the main sipes 72 to 74 communicate with the main grooves 11 to 14, the steering stability on a snow road surface can be improved.

  In particular, at least one of the inner intermediate land portion 22, the center land portion 23 and the outer intermediate land portion 24 (the outer intermediate land portion 22 in FIG. 6), the main sipes 72 to 74 (main sipes 72 in FIG. 6) and the auxiliary sipes 62 to 64 (in FIG. 6, the auxiliary sipe 62) may have a bent shape. With the bent shapes of the main sipes 72 to 74 and the auxiliary sipes 62 to 64, the edge component acts in many directions, so that the steering stability on a snow road surface can be improved.

  In the pneumatic tire, the inner shoulder land portion 21 is formed with a plurality of main sipes 71 located between the lug grooves 41 adjacent in the tire circumferential direction, and the outer shoulder land portion 25 is provided with a tire A plurality of main sipes 75 positioned between the circumferentially adjacent lug grooves 45 are formed. And while the main sipe 71 formed in the inner shoulder land portion 21 communicates with the first main groove 11, the main sipe 75 formed in the outer shoulder land portion 25 communicates with the fourth main groove 14 Not. In this case, since the main sipe 75 of the outer shoulder land portion 25 to which a large amount of load is applied during turning does not communicate with the fourth main groove 14, the adhesion frictional force increases with the increase of the ground contact area. The stability can be effectively improved.

  In the pneumatic tire described above, an auxiliary sipe 65 is provided between the closed end of the lug groove 45 formed in the outer shoulder land portion 25 and the fourth main groove 14 and is formed in the inner shoulder land portion 21. There is no auxiliary sipe (corresponding to the auxiliary sipe 65) connecting the closed end of the lug groove 41 and the first main groove 11 between them. In this case, by providing the auxiliary sipe 65 connecting the closed end of the lug groove 45 formed on the outer shoulder land portion 25 and the fourth main groove 14, drainage performance is improved and steering stability on a wet road surface is improved. can do.

  In a pneumatic tire having a tire size of 225 / 65R17 and having a tread portion, a pair of sidewall portions and a pair of bead portions, and in which a mounting direction to a vehicle is specified, four main tires extending in the tire circumferential direction to the tread portion The first main groove, the second main groove, and the third main groove in which grooves are formed, and five rows of land portions are partitioned by these main grooves, and four main grooves are sequentially arranged from the inside to the outside of the vehicle And an inner shoulder land, an inner intermediate land, a center land, an outer intermediate land and an outer shoulder land, in which five rows of lands are sequentially arranged from the vehicle inner side to the vehicle outer side, and In each of the inner shoulder land portion and the outer shoulder land portion, a narrow groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed, and each narrow groove and the corresponding first main groove or Fourth main groove A narrow rib extending in the circumferential direction of the tire is defined between the inner middle land portion and a plurality of lug grooves having one end opened in the first main groove on the inner side of the vehicle and the other end closed in the inner middle land portion A plurality of lug grooves are formed in the center land portion, one end being open to the second main groove inside the vehicle and the other end being closed in the center land portion, and the outside middle land portion is provided with a fourth end groove outside the vehicle A plurality of lug grooves open in the main groove and closed at the other end in the outer intermediate land portion are formed, and there is no lug groove opened in the third main groove outside the vehicle, and the inner intermediate land portion and the center land portion And a plurality of auxiliary sipes extending from the closed end of the lug groove and communicating with the main groove located on the closed end side of the lug groove in each of the outer intermediate land portions, and the lug groove adjacent in the tire circumferential direction The tires of Examples 1 to 15 were produced having a structure in which the main sipes located between them were formed.

  For comparison, all of the lug grooves formed in the inner middle land, the center land and the outer middle land are arranged to open toward the vehicle inner side, and the sipes are provided only in the inner shoulder land. A tire of a conventional example having substantially the same structure as Example 1 except for the above was prepared. A comparative example having a structure substantially the same as that of Example 1 except that all of the lug grooves formed in the inner intermediate land portion, the center land portion, and the outer intermediate land portion are arranged to open toward the vehicle inner side. I prepared a tire.

  In the tire of the conventional example and the comparative example and the examples 1 to 15, the ratio of the length of the lug groove to the width direction of the lug groove in the opening direction of the lug groove L3 / W3, L2 / W2, L1 / W1, tire circumference of the lug groove Inclination angles θ3, θ2, θ1 with respect to direction, ratio of protrusion length of narrow groove to narrow groove to narrow rib width at inner shoulder land portion Li / Wi, narrow narrow lug groove to width of narrow rib at outer shoulder land portion The ratio Lo / Wo of the protruding length to the rib and the shape of each lug groove are as shown in Tables 1 and 2. With respect to the opening direction of the lug grooves, "IN" means a state of opening toward the inside of the vehicle, and "OUT" means a state of opening toward the outside of the vehicle.

  With respect to these test tires, the steering stability on a snow road surface, the steering stability on a wet road surface, and the external noise were evaluated by the following test methods, and the results are also shown in Table 1 and Table 2.

Steering stability on snow:
Each test tire is assembled on a wheel of rim size 17 × 7 J and mounted on a 2400 cc SUV vehicle (front wheel drive vehicle), air pressure after warm-up is 230 kPa, and sensory evaluation by test driver when traveling on snow road surface Carried out. The evaluation results are indicated by an index where the conventional example is 100. The larger the index value, the better the steering stability on a snow road surface.

Steering stability on wet road surfaces:
Each test tire was assembled to a wheel of rim size 17 × 7 J and mounted on a 2400 cc SUV vehicle (front wheel drive vehicle), air pressure after warm-up was 230 kPa, and sensory evaluation by test driver when traveling on wet road surface Carried out. The evaluation results are indicated by an index where the conventional example is 100. The larger the index value, the better the steering stability on a wet road surface.

Outside noise:
Each test tire is assembled to a wheel of rim size 17 × 7 J and mounted on a 2400 cc SUV vehicle (front wheel drive vehicle), and the air pressure after warm-up is 230 kPa, and the test according to ECE R117 is performed. Was measured. The evaluation results were shown using an inverse number of the measured value, and an index with the conventional example as 100. The larger the index value, the less the external noise.

  As can be seen from Tables 1 and 2, the tires of Examples 1 to 15 have good steering stability on a snow road surface and steering stability on a wet road surface in comparison with the conventional example and the comparative example, and Outside noise was reduced.

  Next, in a pneumatic tire having a tire size of 225 / 65R17 and having a tread portion, a pair of sidewall portions and a pair of bead portions, and in which the mounting direction to the vehicle is specified, the tire portion is extended in the tire circumferential direction A first main groove, a second main groove, and a fourth main groove in which five rows of land portions are defined by the main grooves, and the four main grooves are sequentially arranged from the vehicle inner side toward the vehicle outer side An inner shoulder land, an inner intermediate land, a center land, an outer intermediate land and an outer shoulder, including three main grooves and a fourth main groove, in which five rows of lands are sequentially arranged from the vehicle inner side toward the vehicle outer side A narrow groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed in each of the inner shoulder land and the outer shoulder land including the land portion, and each narrow groove and the corresponding first Main groove or second A plurality of narrow ribs extending in the tire circumferential direction are defined between the main groove and one end of the inner middle land portion is open to the first main groove on the vehicle inner side and the other end is closed in the inner middle land portion. A lug groove is formed, a center land portion is formed with a plurality of lug grooves having one end opened to the third main groove on the vehicle outer side and the other end closed in the center land portion, and an outer intermediate land portion is formed with one end on the vehicle outer side A plurality of lug grooves are formed in the fourth main groove and closed at the other end in the outer intermediate land portion, and there is no lug groove opened in the second main groove on the inner side of the vehicle. Each of the center land portion and the outer intermediate land portion is adjacent to the tire circumferential direction with a plurality of auxiliary sipes that extend from the closed end of the lug groove and communicate with the main groove located on the closed end side of the lug groove. Manufacture of the tire of Examples 16 to 30 having a structure in which the main sipes located between the fitting lug grooves are formed. It was.

  For comparison, all of the lug grooves formed in the inner middle land, the center land and the outer middle land are arranged to open toward the vehicle inner side, and the sipes are provided only in the inner shoulder land. A conventional tire having substantially the same structure as that of Example 16 except for the above was prepared. A comparative example having substantially the same structure as that of Example 16 except that all of the lug grooves formed in the inner intermediate land portion, the center land portion and the outer intermediate land portion are arranged to open toward the vehicle inner side. I prepared a tire.

  In the tires of the conventional example and the comparative example and the examples 16 to 30, the ratio of the length of the lug groove to the width direction of the lug groove in the opening direction of the lug groove L3 / W3, L2 / W2, L1 / W1, tire circumference of the lug groove Inclination angles θ3, θ2, θ1 with respect to direction, ratio of protrusion length of narrow groove to narrow groove to narrow rib width at inner shoulder land portion Li / Wi, narrow narrow lug groove to width of narrow rib at outer shoulder land portion The ratio Lo / Wo of the protruding length to the rib and the shape of each lug groove are as shown in Tables 1 and 2. With respect to the opening direction of the lug grooves, "IN" means a state of opening toward the inside of the vehicle, and "OUT" means a state of opening toward the outside of the vehicle.

  For these test tires, the steering stability on a snow road surface, the steering stability on a wet road surface, and the external noise were evaluated by the same test method as described above, and the results are shown in Table 3 and Table 4.

  As can be seen from Tables 3 and 4, the tires of Examples 16 to 30 have good steering stability on a snow road surface and steering stability on a wet road surface in comparison with the conventional example and the comparative example, and Outside noise was reduced.

DESCRIPTION OF SYMBOLS 1 tread part 2 side wall part 3 bead part 10, 11, 12, 13, 14 main groove 20, 21, 22, 23, 24, 25 land part 31, 35 narrow groove 41, 42A, 42B, 43A, 43B, 44A , 44B, 45 lug grooves 51, 55 thin ribs 61, 62, 63, 64, 65 auxiliary sipes 71, 72, 73, 74, 75 main sipes

Claims (17)

A tread portion extending in the circumferential direction of the tire and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radial direction inner side of the sidewall portions In a pneumatic tire having a mounting direction specified for the vehicle,
Four main grooves extending in the circumferential direction of the tire are formed in the tread portion, and five rows of land portions are divided by these main grooves, and the four main grooves are sequentially arranged from the inside to the outside of the vehicle An inner shoulder land portion, an inner intermediate land portion including the first main groove, the second main groove, the third main groove, and the fourth main groove, wherein the land portions of the five rows are sequentially arranged from the vehicle inner side toward the vehicle outer side , Center land, outer middle land and outer shoulder land,
A narrow groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed in each of the inner shoulder land portion and the outer shoulder land portion, and each narrow groove and the corresponding first main groove or Between the fourth main groove and a narrow rib extending in the circumferential direction of the tire,
The inner middle land portion is formed with a plurality of lug grooves having one end opened to the first main groove inside the vehicle and the other end closed in the inner middle land portion, and the center land portion has one end second to the vehicle inner side A plurality of lug grooves are formed in the main groove and the other end is closed in the center land portion, and one end of the outer intermediate land portion is open in the fourth main groove on the vehicle outer side and the other end is in the outer intermediate land portion. And a plurality of lug grooves closed at the end of the vehicle, and there is no lug groove opened in the third main groove outside the vehicle,
Each of the inner intermediate land portion, the center land portion and the outer intermediate land portion includes a plurality of extending from the closed end of the lug groove and communicating with a main groove located on the closed end side of the lug groove. A pneumatic tire characterized in that an auxiliary sipe and a main sipe located between mutually adjacent lug grooves in the tire circumferential direction are formed. A tread portion extending in the circumferential direction of the tire and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radial direction inner side of the sidewall portions In a pneumatic tire having a mounting direction specified for the vehicle,
Four main grooves extending in the circumferential direction of the tire are formed in the tread portion, and five rows of land portions are divided by these main grooves, and the four main grooves are sequentially arranged from the inside to the outside of the vehicle An inner shoulder land portion, an inner intermediate land portion including the first main groove, the second main groove, the third main groove, and the fourth main groove, wherein the land portions of the five rows are sequentially arranged from the vehicle inner side toward the vehicle outer side , Center land, outer middle land and outer shoulder land,
A narrow groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction are formed in each of the inner shoulder land portion and the outer shoulder land portion, and each narrow groove and the corresponding first main groove or Between the fourth main groove and a narrow rib extending in the circumferential direction of the tire,
The inner middle land portion is formed with a plurality of lug grooves, one end of which is open to the first main groove inside the vehicle and the other end is closed in the inner middle land portion, and the center land portion has a third end which is third on the vehicle outer side. A plurality of lug grooves are formed in the main groove and the other end is closed in the center land portion, and one end of the outer intermediate land portion is open in the fourth main groove on the vehicle outer side and the other end is in the outer intermediate land portion. And a plurality of lug grooves closed at the end of the vehicle, and there is no lug groove opened in the second main groove inside the vehicle,
Each of the inner intermediate land portion, the center land portion and the outer intermediate land portion includes a plurality of extending from the closed end of the lug groove and communicating with a main groove located on the closed end side of the lug groove. A pneumatic tire characterized in that an auxiliary sipe and a main sipe located between mutually adjacent lug grooves in the tire circumferential direction are formed.   The ratio L3 / W3 of the length L3 of the lug groove formed in the outer intermediate land portion to the width W3 of the outer intermediate land portion is 0.1 or more and 0.8 or less. The pneumatic tire according to.   The ratio L2 / W2 of the length L2 of the lug groove formed in the center land portion to the width W2 of the center land portion is 0.1 or more and 0.8 or less. The pneumatic tire described in.   The ratio L1 / W1 of the length L1 of the lug groove formed in the inner middle land portion to the width W1 of the inner middle land portion is 0.1 or more and 0.8 or less. The pneumatic tire according to any one of the above.   The pneumatic tire according to any one of claims 1 to 5, wherein an inclination angle θ3 of the lug grooves formed in the outer intermediate land portion with respect to the tire circumferential direction is 30 ° or more and 85 ° or less.   The pneumatic tire according to any one of claims 1 to 6, wherein an inclination angle θ2 with respect to a tire circumferential direction of the lug grooves formed in the center land portion is 30 ° or more and 85 ° or less.   The pneumatic tire according to any one of claims 1 to 7, wherein an inclination angle θ1 of the lug grooves formed in the inner intermediate land portion with respect to the tire circumferential direction is 30 ° or more and 85 ° or less.   A lug groove formed in the inner shoulder land portion terminates in the narrow rib across the narrow groove, and a projection length of the lug groove to the narrow rib with respect to a width Wi of the narrow rib in the inner shoulder land portion The pneumatic tire according to any one of claims 1 to 8, wherein a ratio Li / Wi of the length Li is 0.2 or more and 0.8 or less.   A lug groove formed in the outer shoulder land portion terminates in the narrow rib across the narrow groove, and a projection length of the lug groove to the narrow rib with respect to a width Wo of the narrow rib in the outer shoulder land portion The pneumatic tire according to any one of claims 1 to 9, wherein a ratio Lo / Wo of the width Lo is 0.2 or more and 0.8 or less.   The pneumatic tire according to any one of claims 1 to 10, wherein the lug grooves formed in the inner middle land portion, the center land portion and the outer middle land portion have a linear shape.   The pneumatic tire according to any one of claims 1 to 11, wherein both ends of the main sipe communicate with main grooves located on both sides of the main sipe.   The air according to any one of claims 1 to 12, wherein the main sipe and the auxiliary sipe have a bent shape in at least one of the inner middle land portion, the center land portion, and the outer middle land portion. Containing tire.   A main sipe is formed in each of the inner shoulder land portion and the outer shoulder land portion, between the lug grooves adjacent in the tire circumferential direction, and the main sipe formed in the outer shoulder land portion is The pneumatic tire according to any one of claims 1 to 13, wherein the main sipe which is in communication with the four main grooves and which is formed in the inner shoulder land portion is not in communication with the first main groove.   A main sipe is formed in each of the inner shoulder land portion and the outer shoulder land portion and located between the lug grooves adjacent in the tire circumferential direction, and the main sipe formed in the inner shoulder land portion is The pneumatic tire according to any one of claims 1 to 13, wherein the main sipe communicated with the one main groove and formed in the outer shoulder land portion is not in communication with the fourth main groove.   Between the closed end of the lug groove formed in the inner shoulder land portion and the first main groove, there is an auxiliary sipe connecting the both, and the closed end and the fourth end of the lug groove formed in the outer shoulder land portion. The pneumatic tire according to any one of claims 1 to 13, wherein there is no auxiliary sipe connecting the two to the main groove.   Between the closed end of the lug groove formed in the outer shoulder land portion and the fourth main groove, there is an auxiliary sipe connecting the both, and the closed end and the first end of the lug groove formed in the inner shoulder land portion. The pneumatic tire according to any one of claims 1 to 13, wherein there is no auxiliary sipe connecting the two to the main groove.

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