JP7031213B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire in which the mounting direction with respect to the 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 to reduce the noise outside the vehicle. Regarding pneumatic tires.

In a pneumatic tire whose mounting direction with respect to the vehicle is specified, four main grooves extending in the tire circumferential direction are formed in the tread portion, and the five rows of land portions are divided by these main grooves and are located between the main grooves. It has been proposed to form multiple lug grooves in each land area that extend in the tire width direction and communicate with the main groove on the inside of the vehicle, while not communicating with the main groove on the outside of the vehicle and terminate in the land area. (See, for example, Patent Document 1).

In the pneumatic tire configured in this way, each of the lug grooves formed in the land portion located between the main grooves has a structure in which one end opens in the main groove and the other end ends in the land portion. It is expected to exhibit excellent steering stability on wet road surfaces while maintaining sufficient rigidity of each land area. Further, since all of these lug grooves are open toward the inside of the vehicle, it is expected that pumping noise and pattern noise during traveling are radiated toward the inside of the vehicle to reduce the noise outside the vehicle. However, in recent years, there has been a demand for further improvement in steering stability and noise performance on wet road surfaces. In addition, all-season tires are required to exhibit excellent steering stability not only on wet road surfaces but also on snowy road surfaces.

International release WO2015 / 005194

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

The first pneumatic tire of the present invention for achieving the above object includes a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these. In a pneumatic tire that is provided with a pair of bead portions arranged inside the tire radial direction of the sidewall portion and whose mounting direction with respect to the vehicle is specified.
Four main grooves extending in the tire circumferential direction were formed in the tread portion, five rows of land portions were partitioned by these main grooves, and the four main grooves were sequentially arranged from the inside of the vehicle to the outside of the vehicle. Inner shoulder land portion, inner intermediate land portion, including the first main groove, the second main groove, the third main groove, and the fourth main groove, in which the land portions of the five rows are sequentially arranged from the inside of the vehicle to the outside of the vehicle. , Including 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 fine groove and the corresponding first main groove or the corresponding first main groove or Fine ribs extending in the tire circumferential direction are partitioned between the tire and the fourth main groove.
A plurality of lug grooves are formed in the inner intermediate land portion, one end of which opens into the first main groove inside the vehicle and the other end of which closes in the inner intermediate land portion, and one end of the center land portion is the second inside of the vehicle. A plurality of lug grooves are formed that open in the main groove and the other end closes in the center land portion, one end opens in the fourth main groove on the outside of the vehicle in the outer intermediate land portion, and the other end enters the outer intermediate land portion. Multiple lug grooves are formed to close with, and there is no lug groove that opens in the third main groove on the outside of the vehicle.
Each of the inner intermediate land portion, the center land portion, and the outer intermediate land portion has a plurality of lines 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. An auxiliary sipe and a main sipe located between adjacent lug grooves in the tire circumferential direction are formed .
It is characterized in that the main sipe and the auxiliary sipe have a bent shape in at least one of the inner intermediate land portion, the center land portion, and the outer intermediate land portion .

Further, the second pneumatic tire of the present invention for achieving the above object includes a tread portion extending in the tire circumferential direction to form an annular shape, and a pair of sidewall portions arranged on both sides of the tread portion. In a pneumatic tire that is provided with a pair of bead portions arranged inside the tire radial direction of these sidewall portions and whose mounting direction with respect to the vehicle is specified.
Four main grooves extending in the tire circumferential direction were formed in the tread portion, five rows of land portions were partitioned by these main grooves, and the four main grooves were sequentially arranged from the inside of the vehicle to the outside of the vehicle. Inner shoulder land portion, inner intermediate land portion, including the first main groove, the second main groove, the third main groove, and the fourth main groove, in which the land portions of the five rows are sequentially arranged from the inside of the vehicle to the outside of the vehicle. , Including 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 fine groove and the corresponding first main groove or the corresponding first main groove or Fine ribs extending in the tire circumferential direction are partitioned between the tire and the fourth main groove.
A plurality of lug grooves are formed in the inner intermediate land portion, one end of which opens into the first main groove inside the vehicle and the other end of which closes in the inner intermediate land portion, and one end of the center land portion is a third outside the vehicle. A plurality of lug grooves are formed that open in the main groove and the other end closes in the center land portion, one end opens in the fourth main groove on the outside of the vehicle in the outer intermediate land portion, and the other end enters the outer intermediate land portion. Multiple lug grooves are formed to close with, and there is no lug groove that opens 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 has a plurality of lines 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. It is characterized in that an auxiliary sipe and a main sipe located between adjacent lug grooves in the tire circumferential direction are formed.

The present inventor has conducted extensive research on the arrangement of lug grooves with one end closed for a pneumatic tire whose mounting direction is specified for the vehicle, and as a result, all of these lug grooves are opened toward the inside of the vehicle. When the pattern noise generated by the lug groove is reflected in the tire house and emitted to the outside of the vehicle, the radiated noise is added up and becomes a factor of increasing the noise, and further, the vehicle travels on a wet road surface. It was discovered that the water discharged from the lug groove remains in the tire house and causes deterioration of steering stability on a wet road surface, which led to the invention of the present application.

That is, in the first pneumatic tire, the lug groove formed in the inner intermediate land portion and the center land portion opens toward the inside of the vehicle, and the lug groove formed in the outer intermediate land portion opens toward the outside of the vehicle. Therefore, the radiated sound from these lug grooves is dispersed inside the vehicle and outside the vehicle to reduce outside noise, and when traveling on a wet road surface, the drainage from the lug groove is dispersed inside the vehicle and outside the vehicle to reduce the wet road surface. Steering stability is improved. Further, in each of the inner intermediate land portion, the center land portion and the outer intermediate land portion, 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. And the main sipes located between the adjacent lug grooves in the tire circumferential direction are formed, so these main sipes and auxiliary sipes cooperate with the lug grooves to exert an edge effect and are excellent on snow road surfaces. It is possible to demonstrate the steering stability. This makes it possible to improve steering stability on snowy roads and steering stability on wet roads, and to reduce noise outside the vehicle. In particular, the first pneumatic tire is advantageous in improving steering stability on snowy road surfaces and reducing outside noise.

Further, in the second pneumatic tire, the lug groove formed in the inner intermediate land portion opens toward the inside of the vehicle, and the lug groove formed in the center land portion and the outer intermediate land portion opens toward the outside of the vehicle. Therefore, the radiated sound from these lug grooves is dispersed inside the vehicle and outside the vehicle to reduce outside noise, and when traveling on a wet road surface, the drainage from the lug groove is dispersed inside the vehicle and outside the vehicle to reduce the wet road surface. Steering stability is improved. Further, in each of the inner intermediate land portion, the center land portion and the outer intermediate land portion, 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. And the main sipes located between the adjacent lug grooves in the tire circumferential direction are formed, so these main sipes and auxiliary sipes cooperate with the lug grooves to exert an edge effect and are excellent on snow road surfaces. It is possible to demonstrate the steering stability. This makes it possible to improve steering stability on snowy roads and steering stability on wet roads, and to reduce noise outside the vehicle. In particular, the second pneumatic tire is advantageous in improving the steering stability on a snowy road surface and improving the steering stability on a wet road surface.

In any structure, 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 fine groove and the corresponding first groove are formed. Fine ribs extending in the tire circumferential direction are partitioned between the 1st main groove or the 4th main groove, and these are steered on a wet road surface while ensuring the rigidity of the inner shoulder land portion and the outer shoulder land portion. 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 groove 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 intermediate land portion to the width W1 of the inner intermediate land portion is preferably 0.1 or more and 0.8 or less. As a result, it is possible to improve the steering stability on a wet road surface and reduce the noise outside the vehicle while maintaining good steering stability on a snowy road surface.

The inclination angle θ3 of the lug groove formed in the outer intermediate land portion with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. The inclination angle θ2 of the lug groove formed in the land portion of the center with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. The inclination angle θ1 of the lug groove formed in the inner intermediate land portion with respect to the tire circumferential direction is preferably 30 ° or more and 85 ° or less. As a result, it is possible to improve the steering stability on a wet road surface and reduce the noise outside the vehicle while maintaining good steering stability on a snowy road surface.

The lug groove formed on the inner shoulder land portion is terminated in the fine rib across the narrow groove, and the ratio of the protrusion length Li of the lug groove to the fine rib to the width Wi of the fine 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 in the outer shoulder land portion is terminated in the fine rib across the narrow groove, and the ratio of the protrusion length Lo of the lug groove to the fine rib to the width Wo of the fine rib in the outer shoulder land portion. Lo / Wo is preferably 0.2 or more and 0.8 or less. As a result, it is possible to improve the steering stability on a wet road surface and reduce the noise outside the vehicle while maintaining good steering stability on a snowy road surface.

Further, it is preferable that the lug grooves formed in the inner intermediate land portion, the center land portion and the outer intermediate 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, so that the shear force of the snow column increases and the steering stability on the snow road surface is improved. Can be done.

It is preferable that both ends of the main sipe communicate with the main grooves located on both sides of the main sipe. By communicating both ends of the main pavement with the main groove, the land portion is easily deformed, so that the steering stability on a snowy 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 intermediate land portion, the center land portion and the outer intermediate land portion. Since the main pavement and the auxiliary pavement have a bent shape, the edge component acts in many directions, so that the steering stability on a snowy road surface can be improved.

In the present invention, each of the inner shoulder land portion and the outer shoulder land portion is formed with a main sipe located between the lug grooves adjacent to each other in the tire circumferential direction, and the main sipe formed on the outer shoulder land portion. Can adopt a structure in which the main sipe formed in the land portion of the inner shoulder communicates with the fourth main groove and does not communicate with the first main groove. In this case, since the main pavement of the outer shoulder land portion, which is heavily loaded during turning, communicates with the fourth main groove, the steering stability on a snowy road surface can be effectively improved.

Further, in the present invention, a 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. It is possible to adopt a structure in which the sipes communicate with the first main groove and the main sipes formed on the outer shoulder land portion do not communicate with the fourth main groove. In this case, since the main sipe on the land of the outer shoulder, which is heavily loaded during turning, does not communicate with the fourth main groove, the adhesive friction force increases as the ground contact area increases, and steering stability on wet road surfaces is improved. It can be effectively improved.

In the present invention, there is an auxiliary sipe connecting the closed end of the lug groove formed in the land portion of the inner shoulder and the first main groove, and the closed end of the lug groove formed in the land portion of the outer shoulder. It is possible to adopt a structure in which there is no auxiliary sipe connecting the two with the fourth main groove. In this case, the noise outside the vehicle is reduced by the absence of the auxiliary sipes connecting the closed end of the lug groove formed in the land portion of the outer shoulder and the fourth main groove, and the closed end of the lug groove formed in the land portion of the inner shoulder. By providing an auxiliary sipe that connects the first main groove and the first main groove, it is possible to improve the steering stability on a snowy road surface.

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

It is a meridian cross-sectional view which shows the pneumatic tire which concerns on 1st Embodiment of this invention. It is a developed view which shows the tread pattern of the pneumatic tire of FIG. FIG. 3 is an enlarged plan view showing the tread pattern of FIG. 2. It is a meridian sectional view which shows the pneumatic tire which concerns on 2nd Embodiment of this invention. It is a developed view which shows the tread pattern of the pneumatic tire of FIG. It is a top view which shows the tread pattern of FIG. 5 enlarged.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show a pneumatic tire according to the first embodiment of the present invention. This pneumatic tire is a tire in which the mounting direction of the front and back of the tire is specified when the tire is mounted on the vehicle. 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 of the present embodiment has a tread portion 1 extending in the tire circumferential direction and forming an annular shape, and a pair of sidewall portions 2 and 2 arranged on both sides of the tread portion 1. And a pair of bead portions 3 and 3 arranged inside the sidewall portions 2 in the tire radial direction.

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 radial direction of the tire, and is folded back from the inside to the outside of the tire around the bead core 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is arranged 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. These belt layers 7 include a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect 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 to, for example, in the range of 10 ° to 40 °. As the reinforcing cord of the belt layer 7, a steel cord is preferably used. At least one belt cover layer 8 having reinforcing cords arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is arranged on the outer peripheral side of the belt layer 7 for the purpose of improving high-speed durability. There is. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

The above-mentioned tire internal structure shows a typical example of a pneumatic tire, but is not limited thereto.

As shown in FIG. 2, four main grooves 10 extending in the tire circumferential direction are formed in the tread portion 1, and five rows of land portions 20 are partitioned by these four main grooves 10. The main groove 10 is a groove that carries a main drainage function, the groove width is set in the range of 6.0 mm to 12.0 mm, and the groove depth is set in the 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 inside of the vehicle to the outside of the vehicle, and five rows of land portions 20 are vehicles. It includes 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 arranged sequentially from the inside to the outside of the vehicle.

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

A plurality of lug grooves 42A having one end opened in the first main groove 11 inside the vehicle and the other end closed in the inner intermediate land portion 22 are formed in the inner intermediate land portion 22 at intervals in the tire circumferential direction. Has been done. A plurality of lug grooves 43A having one end opened in the second main groove 12 inside the vehicle and the other end closed in the center land portion 23 are formed in the center land portion 23 at intervals in the tire circumferential direction. There is. In the outer intermediate land portion 24, a plurality of lug grooves 44A having one end opened in the fourth main groove 14 on the outer side of the vehicle and the other end closed in the outer intermediate land portion 24 are formed at intervals in the tire circumferential direction. Has been done. There is no lug groove that opens in the third main groove 13 on the outside of the vehicle, and the edge portions of the center land portion 23 and the outer intermediate land portion 24 on the third main groove 13 side are continuous without being divided by the lug groove. Is postponed.

Further, in the inner intermediate land portion 22, a plurality of auxiliary sipes 62 extending from the closed end of the lug groove 42A and communicating with the second main groove 12 located on the closed end side of the lug groove 42A, and a tire circumference. A main sipe 72 located between the lug grooves 42A adjacent to each other in the direction is formed. These auxiliary sipes 62 and 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 43A and communicating with the third main groove 13 located on the closed end side of the lug groove 43A are adjacent to each other in the tire circumferential direction. A main sipe 73 located between the matching lug grooves 43A is formed. These auxiliary sipes 63 and 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 a plurality of auxiliary sipes 64 in the tire circumferential direction. A main sipe 74 located between adjacent lug grooves 44A is formed. These auxiliary sipes 64 and main sipes 74 extend in the tire width direction and are alternately arranged along the tire circumferential direction.

In the pneumatic tire of 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 inside of the vehicle, and the lugs formed in the outer intermediate land portion 24. Since the groove 44A opens toward the outside of the vehicle, the radiated sound from these lug grooves 42A to 44A is dispersed inside the vehicle and outside the vehicle, and the noise outside the vehicle is reduced. Moreover, when traveling on a wet road surface, drainage from the lug grooves 42A to 44A is dispersed inside the vehicle and outside the vehicle, improving steering stability on the wet road surface. Further, each of the inner intermediate land portion 22, the center land portion 23 and the outer intermediate land portion 24 extends from the closed end of the lug grooves 42A to 44A and is mainly 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 groove 10 and main sipes 72 to 74 located between the lug grooves 42A to 44A adjacent to each other in the tire circumferential direction are formed, these main sipes 72 to The 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 snowy road surface. This makes it possible to improve steering stability on snowy roads and steering stability on wet roads, and to reduce noise outside the vehicle. In particular, according to the above structure, it is possible to effectively improve the steering stability on a snowy road surface and effectively reduce the noise outside the vehicle.

Here, each of the inner shoulder land portion 21 and the outer shoulder land portion 25 is formed with 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. , It is possible to ensure good steering stability on wet road surfaces. Further, since the fine ribs 51 and 55 extending in the tire circumferential direction are partitioned between the fine grooves 31 and 35 and the corresponding first main groove 11 or the fourth main groove 14, these fine ribs 51 , 55 contribute to the reduction of outside noise while ensuring the rigidity of the inner shoulder land portion 21 and the outer shoulder land portion 25.

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 less than 0.1, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio L3 / W3 is larger than 0.8, the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced, and in addition, the generation of pumping noise is effective. It cannot be suppressed, and the effect of reducing external noise is reduced. For the lug groove 44A, the ratio L3 / W3 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, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio L2 / W2 is larger than 0.8, the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced, and in addition, the generation of pumping noise is effective. It cannot be suppressed, and the effect of reducing external noise is reduced. For the lug groove 43A, the ratio L2 / W2 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, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio L1 / W1 is larger than 0.8, the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced, and in addition, the generation of pumping noise is effective. It cannot be suppressed, and the effect of reducing external noise is reduced. For the lug groove 42A, the ratio L1 / W1 is preferably 0.5 or more and 0.8 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 X1> X2, 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 between the land portions 22 to 24 becomes large, and the amount of deformation generated in the main grooves 11 to 14 when touching the ground becomes different, so that the frequency of the air column resonance sound (standing wave) is dispersed, and the noise outside the vehicle is effective. Can be reduced.

In the pneumatic tire, as shown in FIG. 3, the inclination angle θ3 of the lug groove 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 groove 44A is smaller than 30 °, the snow column shearing force cannot be sufficiently obtained. On the contrary, when the inclination angle θ3 of the lug groove 44A is larger than 85 °, the drainage property is lowered, and the rigidity of the outer intermediate land portion 24 is increased, so that the outer intermediate land portion when the ground pressure acts is applied. Since the deformation of the 24 is small, the generation of the standing wave cannot be sufficiently suppressed, and the generation of the noise outside the vehicle cannot be effectively suppressed. For the lug groove 44A, it is desirable that the inclination angle θ3 is 45 ° or more and 75 ° or less.

The inclination angle θ2 of the lug groove 43A 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 groove 43A is smaller than 30 °, the snow column shearing force cannot be sufficiently obtained. On the contrary, when the inclination angle θ2 of the lug groove 43A is larger than 85 °, the drainage property is lowered, and the rigidity of the center land portion 23 is increased, so that the center land portion 23 is affected by the contact pressure. Since the deformation is small, the generation of standing waves cannot be sufficiently suppressed, and the generation of noise outside the vehicle cannot be effectively suppressed. For the lug groove 43A, it is desirable that the inclination angle θ2 is 45 ° or more and 75 ° or less.

The inclination angle θ1 of the lug groove 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. If the inclination angle θ1 of the lug groove 42A is smaller than 30 °, the snow column shearing force cannot be sufficiently obtained. On the contrary, when the inclination angle θ1 of the lug groove 42A is larger than 85 °, the drainage property is lowered, and the rigidity of the inner intermediate land portion 22 is increased, so that the inner intermediate land portion when the ground pressure acts is applied. Since the deformation of 22 becomes small, the generation of standing waves cannot be sufficiently suppressed, and the generation of noise outside the vehicle cannot be effectively suppressed. For the lug groove 42A, it is desirable that the inclination angle θ1 is 45 ° or more and 75 ° or less.

The inclination angles θ1 to θ3 of the lug grooves 42A to 44A are such that in each of the lug grooves 42A to 44A, a straight line passing through the groove width center position at the open end and the groove width center position at the closed end is relative to the tire circumferential direction. It is the angle of the tire.

In the pneumatic tire, the lug groove 41 formed in the inner shoulder land portion 21 is terminated in the fine rib 51 across the narrow groove 31, and the lug groove 41 with respect to the width Wi of the fine rib 51 in the inner shoulder land portion 21. It is preferable that the ratio Li / Wi of the protrusion length Li to the fine rib 51 is 0.2 or more and 0.8 or less. If the ratio Li / Wi is less than 0.2, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio Li / Wi is larger than 0.8, the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced, and the effect of reducing the noise outside the vehicle is reduced. 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 is terminated in the fine rib 55 across the narrow groove 35, and the lug groove 45 of the lug groove 45 with respect to the width Wo of the fine rib 55 in the outer shoulder land portion 25. It is preferable that the ratio Lo / Wo of the protrusion length Lo to the fine rib 55 is 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 cannot be effectively improved. On the contrary, when the ratio Lo / Wo is larger than 0.8, the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced, and the effect of reducing the noise outside the vehicle is reduced. do. The ratio Lo / Wo is preferably 0.3 or more and 0.7 or less.

In the pneumatic tire, 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 preferably 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 column shear force increases and the steering is stable on the snow road surface. The sex can be improved.

In the pneumatic tire, both ends of the main sipes 72 to 74 may communicate with the main grooves 11 to 14 located on both sides of the main sipes 72 to 74, respectively. Since both ends of the main pavement 72 to 74 communicate with the main grooves 11 to 14, the land portions 22 to 24 are easily deformed, so that the steering stability on a snowy road surface can be improved.

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

In the pneumatic tire, a plurality of main sipes 71 located between the lug grooves 41 adjacent to each other in the tire circumferential direction are formed on the inner shoulder land portion 21, and the tire is formed on the outer shoulder land portion 25. A plurality of main sipes 75 located between the lug grooves 45 adjacent to each other in the circumferential direction are formed. The main sipe 75 formed in the outer shoulder land portion 25 communicates with the fourth main groove 14, while 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 pavement 75 of the outer shoulder land portion 25, which is heavily loaded during turning, communicates with the fourth main groove 14, the steering stability on a snowy road surface can be effectively improved.

In the pneumatic tire, an auxiliary sipe 61 connecting the closed end of the lug groove 41 formed in the inner shoulder land portion 21 and the first main groove 11 exists, 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. In this case, the noise outside the vehicle is reduced by the absence of the auxiliary sipes connecting the closed end of the lug groove 45 formed in the outer shoulder land portion 25 and the fourth main groove 14, and the lug formed in the inner shoulder land portion 21. By providing the auxiliary sipes 61 connecting the closed end of the groove 41 and the first main groove 11, it is possible to improve the steering stability on a snowy road surface.

4 to 6 show a pneumatic tire according to the second embodiment of the present invention. This pneumatic tire is a tire in which the mounting direction of the front and back of the tire is specified when the tire is mounted on the vehicle. In FIGS. 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. In the second embodiment, the structure of 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 is different from that of the first embodiment. In FIGS. 4 to 6, the same objects as those in FIGS. 1 to 3 are designated by the same reference numerals, and detailed description of the parts thereof will be 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. Fine ribs 51 extending in the tire circumferential direction are partitioned between the fine grooves 31 and the first main groove 11 at intervals. On the other hand, in the outer shoulder land portion 25, one narrow groove 35 extending in the tire circumferential direction is formed, and a plurality of lug grooves 45 extending in the tire width direction are formed at intervals in the tire circumferential direction. A fine rib 55 extending in the tire circumferential direction is partitioned between the fine groove 35 and the fourth main groove 14. Further, each of the fine ribs 51 and 55 is continuous in the tire circumferential direction without being divided by the lug grooves 41 and 45.

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

Further, in the inner intermediate land portion 22, a plurality of auxiliary sipes 62 extending from the closed end of the lug groove 42B and communicating with the second main groove 12 located on the closed end side of the lug groove 42B, and a tire circumference. A main sipe 72 located between the lug grooves 42B adjacent to each other in the direction is formed. These auxiliary sipes 62 and 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 are adjacent to each other in the tire circumferential direction. A main sipe 73 located between the matching lug grooves 43B is formed. These auxiliary sipes 63 and 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 a plurality of auxiliary sipes 64 in the tire circumferential direction. A main sipe 74 located between adjacent lug grooves 44B is formed. These auxiliary sipes 64 and main sipes 74 extend in the tire width direction and are alternately arranged along the tire circumferential direction.

In the pneumatic tire of the second embodiment described above, the lug groove 42B formed in the inner intermediate land portion 22 opens toward the inside of the vehicle, and the lug groove 43B formed in the center land portion 23 and the outer intermediate land portion 24. , 44B opens toward the outside of the vehicle, so that the radiated sound from these lug grooves 42B to 44B is dispersed inside the vehicle and outside the vehicle, and the noise outside the vehicle is reduced. Moreover, when traveling on a wet road surface, drainage from the lug grooves 42B to 44B is dispersed inside the vehicle and outside the vehicle, improving steering stability on the wet road surface. Further, each of the inner intermediate land portion 22, the center land portion 23 and the outer intermediate land portion 24 extends from the closed end of the lug grooves 42A to 44A and is mainly 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 groove 10 and main sipes 72 to 74 located between the lug grooves 42A to 44A adjacent to each other in the tire circumferential direction are formed, these main sipes 72 to The 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 snowy road surface. This makes it possible to improve steering stability on snowy roads and steering stability on wet roads, and to reduce noise outside the vehicle. In particular, according to the above structure, it is possible to effectively improve the steering stability on a snowy road surface and effectively improve the steering stability on a wet road surface.

Here, each of the inner shoulder land portion 21 and the outer shoulder land portion 25 is formed with 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. , It is possible to ensure good steering stability on wet road surfaces. Further, since the fine ribs 51 and 55 extending in the tire circumferential direction are partitioned between the fine grooves 31 and 35 and the corresponding first main groove 11 or the fourth main groove 14, these fine ribs 51 , 55 contribute to the reduction of outside noise while ensuring the rigidity of the inner shoulder land portion 21 and the outer shoulder land portion 25.

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 less than 0.1, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio L3 / W3 is larger than 0.8, the effect of reducing the noise outside the vehicle is reduced, and the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced. do. For the lug groove 44B, the ratio L3 / W3 is preferably 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 less than 0.1, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio L2 / W2 is larger than 0.8, the effect of reducing the noise outside the vehicle is reduced, and the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced. do. For the lug groove 43B, the ratio L2 / W2 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, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio L1 / W1 is larger than 0.8, the effect of reducing the noise outside the vehicle is lowered, and the effect of improving the steering stability on the wet road surface is lowered as the adhesive friction force is reduced. do. For the lug groove 42B, the ratio L1 / W1 is preferably 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, X3> X2, and in particular, X3> X1 =. It is preferable to satisfy the relationship of 1.5 to 2.5 and X3> X2 = 1.5 to 2.5. As a result, the difference in rigidity between the land portions 22 to 24 becomes large, and the amount of deformation generated in the main grooves 11 to 14 when touching the ground becomes different, so that the frequency of the air column resonance sound (standing wave) is dispersed, and the noise outside the vehicle is effective. Can be reduced.

In the pneumatic tire, as shown in FIG. 6, the inclination angle θ3 of the lug groove 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 groove 44B is smaller than 30 °, the snow column shearing force cannot be sufficiently obtained. On the contrary, when the inclination angle θ3 of the lug groove 44B is larger than 85 °, the drainage property is lowered, and the rigidity of the outer intermediate land portion 24 is increased, so that the outer intermediate land portion when the ground pressure acts is applied. Since the deformation of the 24 is small, the generation of the standing wave cannot be sufficiently suppressed, and the generation of the noise outside the vehicle cannot be effectively suppressed. It is desirable that the inclination angle θ3 of the lug groove 44B is 45 ° or more and 75 ° or less.

The inclination angle θ2 of the lug groove 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 groove 43B is smaller than 30 °, the snow column shearing force cannot be sufficiently obtained. On the contrary, when the inclination angle θ2 of the lug groove 43B is larger than 85 °, the drainage property is lowered, and the rigidity of the center land portion 23 is increased, so that the center land portion 23 is affected by the contact pressure. Since the deformation is small, the generation of standing waves cannot be sufficiently suppressed, and the generation of noise outside the vehicle cannot be effectively suppressed. It is desirable that the inclination angle θ2 of the lug groove 43B is 45 ° or more and 75 ° or less.

The inclination angle θ1 of the lug groove 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 groove 42B is smaller than 30 °, the snow column shearing force cannot be sufficiently obtained. On the contrary, when the inclination angle θ1 of the lug groove 42B is larger than 85 °, the drainage property is lowered, and the rigidity of the center land portion 23 is increased, so that the center land portion 23 is affected by the contact pressure. Since the deformation is small, the generation of standing waves cannot be sufficiently suppressed, and the generation of noise outside the vehicle cannot be effectively suppressed. For the lug groove 42B, the inclination angle θ1 is preferably 45 ° or more and 75 ° or less.

The inclination angles θ1 to θ3 of the lug grooves 42B to 44B are such that in each of the lug grooves 42B to 44B, a straight line passing through the groove width center position at the open end and the groove width center position at the closed end is relative to the tire circumferential direction. It is the angle of the tire.

In the pneumatic tire, the lug groove 41 formed in the inner shoulder land portion 21 is terminated in the fine rib 51 across the narrow groove 31, and the lug groove 41 with respect to the width Wi of the fine rib 51 in the inner shoulder land portion 21. It is preferable that the ratio Li / Wi of the protrusion length Li to the fine rib 51 is 0.2 or more and 0.8 or less. If the ratio Li / Wi is less than 0.2, the steering stability on a snowy road surface cannot be effectively improved. On the contrary, when the ratio Li / Wi is larger than 0.8, the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced, and the effect of reducing the noise outside the vehicle is reduced. 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 is terminated in the fine rib 55 across the narrow groove 35, and the lug groove 45 of the lug groove 45 with respect to the width Wo of the fine rib 55 in the outer shoulder land portion 25. It is preferable that the ratio Lo / Wo of the protruding length Lo to the fine rib 55 is 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 cannot be effectively improved. On the contrary, when the ratio Lo / Wo is larger than 0.8, the effect of improving the steering stability on the wet road surface is reduced as the adhesive friction force is reduced, and the effect of reducing the noise outside the vehicle is reduced. do. The ratio Lo / Wo is preferably 0.3 or more and 0.7 or less.

In the pneumatic tire, 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 preferably 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 that the snow column shearing force increases and the steering is stable on the snow road surface. The sex can be improved.

In the pneumatic tire, both ends of the main sipes 72 to 74 may communicate with the main grooves 11 to 14 located on both sides of the main sipes 72 to 74, respectively. Since both ends of the main pavement 72 to 74 communicate with the main grooves 11 to 14, the land portions 22 to 24 are easily deformed, so that the steering stability on a snowy road surface can be improved.

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

In the pneumatic tire, a plurality of main sipes 71 located between the lug grooves 41 adjacent to each other in the tire circumferential direction are formed on the inner shoulder land portion 21, and the tire is formed on the outer shoulder land portion 25. A plurality of main sipes 75 located between the lug grooves 45 adjacent to each other in the circumferential direction are formed. The main sipe 71 formed in the inner shoulder land portion 21 communicates with the first main groove 11, while 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, which is heavily loaded during turning, does not communicate with the fourth main groove 14, the adhesive friction force increases as the ground contact area increases, and maneuvering on a wet road surface Stability can be effectively improved.

In the pneumatic tire, an auxiliary sipe 65 connecting the closed end of the lug groove 45 formed in the outer shoulder land portion 25 and the fourth main groove 14 exists, 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. In this case, by providing an 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 is improved and steering stability on a wet road surface is improved. can do.

In a pneumatic tire with a tire size of 225 / 65R17, which has a tread portion, a pair of sidewall portions, and a pair of bead portions, and whose mounting direction is specified for a vehicle, four main tires extending in the tire circumferential direction are provided on the tread portion. Grooves are formed, and five rows of land areas are divided by these main grooves, and the four main grooves are sequentially arranged from the inside of the vehicle to the outside of the vehicle. The inner shoulder land, the inner middle land, the center land, the outer middle land and the outer shoulder land, in which five rows of land are sequentially arranged from the inside of the vehicle to the outside of the vehicle, including the fourth main groove. Including, each of the inner shoulder land portion and the outer shoulder land portion is formed with a narrow groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction, and each fine groove and the corresponding first main groove or A plurality of fine ribs extending in the tire circumferential direction are partitioned between the tire and the fourth main groove, one end of which is opened in the first main groove inside the vehicle and the other end is closed in the inner intermediate land portion. A book lug groove is formed, one end opens in the second main groove inside the vehicle and the other end closes in the center land part, and one end is formed in the outer intermediate land part. Multiple lug grooves are formed that open in the 4th main groove on the outside of the vehicle and close at the other end in the outer intermediate land, and there is no lug groove that opens in the 3rd main groove on the outside of the vehicle. Each of the tread, the center tread, and the outer intermediate tread has 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, and a tire circumferential direction. The tires of Examples 1 to 15 having a structure in which a main sipe located between adjacent lug grooves were formed were manufactured.

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

In the tires of Conventional Examples, Comparative Examples and Examples 1 to 15, the ratio of the length of the lug groove to the opening direction of the lug groove and the width of the land portion is L3 / W3, L2 / W2, L1 / W1, and the tire circumference of the lug groove. Tilt angles θ3, θ2, θ1 with respect to the direction, ratio of the protrusion length of the lug groove to the fine rib to the width of the fine rib in the land part of the inner shoulder Li / Wi, the fineness of the lug groove to the width of the fine rib in the land part of the outer shoulder The ratio of the protrusion length to the rib Lo / Wo and the shape of each lug groove are as shown in Tables 1 and 2. Regarding the opening direction of the lug groove, "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.

These test tires were evaluated for steering stability on snowy roads, steering stability on wet roads, and noise outside the vehicle by the following test methods, and the results are shown in Tables 1 and 2.

Steering stability on snowy roads:
Each test tire is attached to a wheel with a rim size of 17 x 7J and mounted on an SUV vehicle (front wheel drive vehicle) with a displacement of 2400cc. Carried out. The evaluation results are shown by an index of 100 in the conventional example. The larger this index value is, the better the steering stability on a snowy road surface.

Steering stability on wet roads:
Each test tire is attached to a wheel with a rim size of 17 x 7J and mounted on an SUV vehicle (front wheel drive vehicle) with a displacement of 2400cc. Carried out. The evaluation results are shown by an index of 100 in the conventional example. The larger this index value is, the better the steering stability on a wet road surface is.

Outside noise:
Each test tire was attached to a wheel with a rim size of 17 x 7J and mounted on an SUV vehicle (front wheel drive vehicle) with a displacement of 2400cc. Was measured. The evaluation result is shown by an index of 100 in the conventional example using the reciprocal of the measured value. The larger this index value is, the less the noise outside the vehicle is.

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

Next, in a pneumatic tire having a tire size of 225 / 65R17, including a tread portion, a pair of sidewall portions, and a pair of bead portions, and a mounting direction for a vehicle is specified, the tread portion extends in the tire circumferential direction 4 The main grooves of the book are formed, and the five rows of land parts are divided by these main grooves, and the four main grooves are sequentially arranged from the inside of the vehicle to the outside of the vehicle. Inner shoulder land, inner middle land, center land, outer middle land and outer shoulder with 5 rows of land, including 3 main grooves and 4th main groove, arranged sequentially from the inside of the vehicle to the outside of the vehicle. Including the land portion, each of the inner shoulder land portion and the outer shoulder land portion is formed with a groove extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction, and each groove and the corresponding first groove are formed. Fine ribs extending in the tire circumferential direction are partitioned between the main groove or the fourth main groove, one end opens to the first main groove inside the vehicle in the inner intermediate land portion, and the other end is in the inner intermediate land portion. A plurality of lug grooves to be closed are formed, and a plurality of lug grooves are formed in the center land portion, one end of which opens into the third main groove on the outside of the vehicle and the other end of which closes in the center land portion, and the outer intermediate land portion. A plurality of lug grooves are formed in which one end opens in the fourth main groove on the outside of the vehicle and the other end closes in the outer intermediate land portion, and there is no lug groove that opens in the second main groove on the inside of the vehicle. Each of the inner intermediate tread, the center tread and the outer tread has 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. The tires of Examples 16 to 30 having a structure in which a main sipe located between adjacent lug grooves in the tire circumferential direction were formed were manufactured.

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

In the tires of the conventional example, the comparative example and the examples 16 to 30, the ratio of the length of the lug groove to the opening direction of the lug groove and the width of the land portion is L3 / W3, L2 / W2, L1 / W1, and the tire circumference of the lug groove. Tilt angles θ3, θ2, θ1 with respect to the direction, ratio of the protrusion length of the lug groove to the fine rib to the width of the fine rib in the land part of the inner shoulder Li / Wi, the fineness of the lug groove to the width of the fine rib in the land part of the outer shoulder The ratio of the protrusion length to the rib Lo / Wo and the shape of each lug groove are as shown in Tables 1 and 2. Regarding the opening direction of the lug groove, "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.

These test tires were evaluated for steering stability on snowy roads, steering stability on wet roads, and noise outside the vehicle by the same test method as above, and the results are shown in Tables 3 and 4.

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

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 Fine groove 41,42A, 42B, 43A, 43B, 44A , 44B, 45 Lag groove 51,55 Fine rib 61,62,63,64,65 Auxiliary sipe 71,72,73,74,75 Main sipe

Claims (17)

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the tire radial direction of these sidewall portions. In addition to being prepared, in a pneumatic tire whose mounting direction with respect to the vehicle is specified
Four main grooves extending in the tire circumferential direction were formed in the tread portion, five rows of land portions were partitioned by these main grooves, and the four main grooves were sequentially arranged from the inside of the vehicle to the outside of the vehicle. Inner shoulder land portion, inner intermediate land portion, including the first main groove, the second main groove, the third main groove, and the fourth main groove, in which the land portions of the five rows are sequentially arranged from the inside of the vehicle to the outside of the vehicle. , Including 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 fine groove and the corresponding first main groove or the corresponding first main groove or Fine ribs extending in the tire circumferential direction are partitioned between the tire and the fourth main groove.
A plurality of lug grooves are formed in the inner intermediate land portion, one end of which opens into the first main groove inside the vehicle and the other end of which closes in the inner intermediate land portion, and one end of the center land portion is the second inside of the vehicle. A plurality of lug grooves are formed that open in the main groove and the other end closes in the center land portion, one end opens in the fourth main groove on the outside of the vehicle in the outer intermediate land portion, and the other end enters the outer intermediate land portion. Multiple lug grooves are formed to close with, and there is no lug groove that opens in the third main groove on the outside of the vehicle.
Each of the inner intermediate land portion, the center land portion, and the outer intermediate land portion has a plurality of lines 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. An auxiliary sipe and a main sipe located between adjacent lug grooves in the tire circumferential direction are formed .
A pneumatic tire characterized in that the main sipe and the auxiliary sipe have a bent shape in at least one of the inner intermediate land portion, the center land portion and the outer intermediate land portion . A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the tire radial direction of these sidewall portions. In addition to being prepared, in a pneumatic tire whose mounting direction with respect to the vehicle is specified
Four main grooves extending in the tire circumferential direction were formed in the tread portion, five rows of land portions were partitioned by these main grooves, and the four main grooves were sequentially arranged from the inside of the vehicle to the outside of the vehicle. Inner shoulder land portion, inner intermediate land portion, including the first main groove, the second main groove, the third main groove, and the fourth main groove, in which the land portions of the five rows are sequentially arranged from the inside of the vehicle to the outside of the vehicle. , Including 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 fine groove and the corresponding first main groove or the corresponding first main groove or Fine ribs extending in the tire circumferential direction are partitioned between the tire and the fourth main groove.
A plurality of lug grooves are formed in the inner intermediate land portion, one end of which opens into the first main groove inside the vehicle and the other end of which closes in the inner intermediate land portion, and one end of the center land portion is a third outside the vehicle. A plurality of lug grooves are formed that open in the main groove and the other end closes in the center land portion, one end opens in the fourth main groove on the outside of the vehicle in the outer intermediate land portion, and the other end enters the outer intermediate land portion. Multiple lug grooves are formed to close with, and there is no lug groove that opens 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 has a plurality of lines 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. A pneumatic tire characterized in that an auxiliary sipe and a main sipe located between adjacent lug grooves in the tire circumferential direction are formed. Claim 1 or 2 characterized in that 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. Pneumatic tires listed in. Any of claims 1 to 3, wherein 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. Pneumatic tires listed in Crab. Claims 1 to 4 are characterized in that the ratio L1 / W1 of the length L1 of the lug groove formed in the inner intermediate land portion to the width W1 of the inner intermediate land portion is 0.1 or more and 0.8 or less. Pneumatic tires listed in any of. The pneumatic tire according to any one of claims 1 to 5, wherein the inclination angle θ3 of the lug groove 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 the inclination angle θ2 of the lug groove formed in the center 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 7, wherein the inclination angle θ1 of the lug groove formed in the inner intermediate land portion with respect to the tire circumferential direction is 30 ° or more and 85 ° or less. The lug groove formed in the inner shoulder land portion crosses the narrow groove and terminates in the fine rib, and the protrusion length of the lug groove to the fine rib with respect to the width Wi of the fine rib in the inner shoulder land portion. The pneumatic tire according to any one of claims 1 to 8, wherein the ratio Li / Wi of Li is 0.2 or more and 0.8 or less. The lug groove formed in the outer shoulder land portion crosses the narrow groove and terminates in the fine rib, and the protrusion length of the lug groove to the fine rib with respect to the width Wo of the fine rib in the outer shoulder land portion. The pneumatic tire according to any one of claims 1 to 9, wherein the ratio Lo / Wo of 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 intermediate land portion, the center land portion and the outer intermediate 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 each other in a main groove located on both sides of the main sipe. The pneumatic tire according to claim 2 , wherein the main sipe and the auxiliary sipe have a bent shape in at least one of the inner intermediate land portion, the center land portion, and the outer intermediate land portion. A main sipe located between the adjacent lug grooves 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 outer shoulder land portion is the first. 4. The pneumatic tire according to any one of claims 1 to 13, wherein the main sipe that communicates with the main groove and is formed on the land portion of the inner shoulder is not communicated with the first main groove. A main sipe located between the adjacent lug grooves 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 is the first. 1. The pneumatic tire according to any one of claims 1 to 13, wherein the main sipe that communicates with the main groove and is formed on the land portion of the outer shoulder is not communicated with the fourth main groove. There is an auxiliary sipe connecting the closed end of the lug groove formed on the inner shoulder land portion and the first main groove, and the closed end of the lug groove formed on the outer shoulder land portion and the fourth main groove. 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. There is an auxiliary sipe connecting the closed end of the lug groove formed on the outer shoulder land portion and the fourth main groove, and the closed end of the lug groove formed on the inner shoulder land portion and the first main groove. 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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