JP2020131760A - tire - Google Patents

Abstract

To provide a tire that can be improved in steering stability and noise performance.SOLUTION: A tire has a tread part 2 in which a direction of mounting on a vehicle is specified. A main groove 3 arranged in the tread part 2 includes a first shoulder main groove 5, a second shoulder main groove 6 and a crown main groove 7. A land part 4 partitioned by the main groove 3 includes a first middle land part 11 and a second middle land part 12. At least one of first middle lateral grooves 16 and at least one of second middle lateral grooves 17 have raised portions 18 with bottom surfaces raised respectively. The raised portions 18 are crossed over a center position in a tire shaft direction of the first middle land part 11 or the second middle land part 12. Lengths in the tire shaft direction of the raised portions 18 of the first middle lateral grooves 16 are larger than lengths in the tire shaft direction of the raised portions 18 of the second middle lateral grooves 17.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire, and more particularly to a tire having a tread portion whose mounting direction on a vehicle is specified.

Conventionally, various tires having a tread portion whose mounting direction on a vehicle is specified have been proposed. For example, Patent Document 1 below describes a pneumatic tire having a center land portion, and the center land portion is not crossed over the entire width by a groove having a width of 2 mm or more, but the width is less than 2 mm. There are multiple center sipes. As a result, the pneumatic tire is expected to increase the rigidity of the land portion of the center and improve the steering stability on a dry road surface.

Japanese Unexamined Patent Publication No. 2015-140047

Since the pneumatic tire has high rigidity in the land portion of the center, the hitting sound when the land portion of the center touches the ground is loud and tends to deteriorate the noise performance. As a result of various experiments, the inventors have found that in a tire having a tread portion whose mounting direction on a vehicle is specified, steering stability and noise performance can be improved by defining the arrangement of each lateral groove. Obtained.

The present invention has been devised in view of the above problems, and its main object is to provide a tire capable of improving steering stability and noise performance.

The present invention is a tire having a tread portion whose mounting direction on a vehicle is specified, and the tread portion is located on a first tread end located on the outside of the vehicle when mounted on the vehicle and on the inside of the vehicle when mounted on the vehicle. It has a second tread end, a plurality of main grooves continuously extending in the tire circumferential direction between the first tread end and the second tread end, and a plurality of land portions divided into the main grooves. The main groove includes a first shoulder main groove arranged between the first tread end and the tire equatorial line, and a second shoulder main groove arranged between the second tread end and the tire equatorial line. The land portion includes the crown main groove arranged between the first shoulder main groove and the second shoulder main groove, and the land portion is divided between the first shoulder main groove and the crown main groove. The first middle land portion includes a second middle land portion divided between the second shoulder main groove and the crown main groove, and the first middle land portion includes the first middle land portion. A plurality of first middle tire treads that completely cross the tires are provided, and the second middle tires are provided with a plurality of second middle tires that completely cross the second middle tires, and at least one of the first middle tires. The book and at least one of the second middle lateral grooves have a raised portion having a raised bottom surface, and the raised portion is a center position of the first middle land portion or the second middle land portion in the tire axial direction. The length of the raised portion of the first middle lateral groove in the tire axial direction is larger than the length of the raised portion of the second middle lateral groove in the tire axial direction.

In the tire of the present invention, the length of the raised portion of the first middle lateral groove in the tire axial direction is 1.05 to 1.25 times the length of the raised portion of the second middle lateral groove in the tire axial direction. It is desirable to have it.

In the tire of the present invention, the depth of the raised portion of the first middle lateral groove and the depth of the raised portion of the second middle lateral groove are 0.10 to 0 of the depth of the crown main groove, respectively. It is desirable to be .60 times.

In the tread plan view of the tire of the present invention, each of the first middle lateral groove and the second middle lateral groove extends from the raised portion extending in the tire axial direction and the tire from one end of the raised portion. A first outer portion extending at an angle smaller than the raised portion with respect to the axial direction and a second outer portion extending from the other end of the raised portion at an angle smaller than the raised portion with respect to the tire axial direction. It is desirable to have a curved groove that includes it.

In the tire of the present invention, it is desirable that the curved groove is bent in an S shape.

In the first middle lateral groove and the second middle lateral groove of the tire of the present invention, the length of the raised portion in the tire axial direction is the length of the first outer portion in the tire axial direction and the second outer portion. It is desirable that the length is larger than the length in the tire axial direction.

In the second middle lateral groove of the tire of the present invention, it is desirable that the length of the second outer portion in the tire axial direction is larger than the length of the first outer portion in the tire axial direction.

In the second middle lateral groove of the tire of the present invention, the length of the second outer portion in the tire axial direction is 1.10 to 2.00 times the length of the first outer portion in the tire axial direction. Is desirable.

In the second middle lateral groove of the tire of the present invention, it is desirable that the second outer portion is arranged on the second tread end side of the raised portion.

In the first middle lateral groove of the tire of the present invention, it is desirable that the length of the first outer portion in the tire axial direction is the same as the length of the second outer portion in the tire axial direction.

The present invention is a tire having a tread portion whose mounting direction on a vehicle is specified. The main groove provided in the tread portion includes a first shoulder main groove, a second shoulder main groove, and a crown main groove. Further, the land portion divided into the main ditch includes a first middle land portion and a second middle land portion.

The first middle land portion is provided with a plurality of first middle lateral grooves completely crossing the first middle land portion. The second middle land portion is provided with a plurality of second middle lateral grooves that completely cross the second middle land portion. At least one of the first middle lateral grooves and at least one of the second middle lateral grooves have a raised portion having a raised bottom surface. The raised portion crosses the center position of the first middle land portion or the second middle land portion in the tire axial direction.

In the first middle lateral groove and the second middle lateral groove, the movement of air in the groove can be hindered by the raised portion, and the pumping noise can be suppressed. Further, the first middle lateral groove having the raised portion and the second middle lateral groove serve to maintain the rigidity of each middle land portion and enhance the steering stability.

In the present invention, the length of the raised portion of the first middle lateral groove in the tire axial direction is larger than the length of the raised portion of the second middle lateral groove in the tire axial direction. Such an arrangement of the lateral grooves can relatively increase the rigidity of the first middle land portion. Therefore, when the center of the ground contact surface moves to the first tread end side during turning, the steering response becomes linear and excellent steering stability can be obtained.

It is a development view of the tread part of the tire of one Embodiment of this invention. It is an enlarged view of the 1st middle land part and the 2nd middle land part of FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. It is an enlarged view of the 1st shoulder land part of FIG. FIG. 4 is a cross-sectional view taken along the line BB of FIG. It is an enlarged view of the 2nd shoulder land part of FIG. FIG. 6 is a sectional view taken along line CC of FIG. FIG. 6 is a cross-sectional view taken along the line DD of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. The tire 1 of the present embodiment is suitably used as, for example, a pneumatic tire for a passenger car. However, the present invention is not limited to such an aspect, and may be used for a pneumatic tire for a heavy load or a non-pneumatic tire in which the inside of the tire is not filled with pressurized air.

As shown in FIG. 1, the tire 1 of the present invention has a tread portion 2 whose mounting direction on a vehicle is specified. The tread portion 2 has a first tread end Te1 located outside the vehicle when the tire 1 is mounted on the vehicle, and a second tread end Te2 located inside the vehicle when the tire 1 is mounted on the vehicle. The direction of mounting on the vehicle is indicated by characters or symbols on the sidewall (not shown), for example.

In the case of a pneumatic tire, the first tread end Te1 and the second tread end Te2 are at the most outer contact positions in the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire 1 touches a plane at a camber angle of 0 °. is there. The normal state is a state in which the tire is rim-assembled on the normal rim, the normal internal pressure is applied, and there is no load. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATTA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS AT" The maximum value described in "VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum load capacity", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

The tread portion 2 has a plurality of main grooves 3 continuously extending in the tire circumferential direction between the first tread end Te1 and the second tread end Te2, and a plurality of land portions 4 divided into the main grooves 3. ..

The main groove 3 is a first shoulder main groove 5 arranged between the first tread end Te1 and the tire equator C, and a second shoulder main groove arranged between the second tread end Te2 and the tire equator C. 6 and a crown main groove 7 arranged between the first shoulder main groove 5 and the second shoulder main groove 6.

The distance La in the tire axial direction from the tire equator C to the groove center line of the first shoulder main groove 5 or the second shoulder main groove 6 is preferably, for example, 0.15 to 0.30 times the tread width TW. .. The tread width TW is the distance in the tire axial direction from the first tread end Te1 to the second tread end Te2 in the normal state.

For example, one crown main groove 7 of the present embodiment is provided on the tire equator C. In another aspect of the present invention, for example, two crown main grooves 7 may be provided so as to sandwich the tire equator C.

Each main groove 3 of the present embodiment extends linearly in parallel with, for example, the tire circumferential direction. Each main groove 3 may extend in a wavy shape, for example.

The groove width Wa of each main groove 3 is preferably, for example, 4.0% to 7.0% of the tread width TW. The depth of each main groove 3 is preferably 5 to 10 mm, for example, in the case of a pneumatic tire for a passenger car.

The land portion 4 includes a first middle land portion 11, a second middle land portion 12, a first shoulder land portion 13, and a second shoulder land portion 14. The tread portion 2 of the present embodiment has a so-called 4-rib pattern composed of the above-mentioned three main grooves 3 and four land portions 4. In another aspect of the present invention, for example, the tread portion 2 may be composed of five land portions 4 by arranging two crown main grooves 7.

The first middle land portion 11 is divided between the first shoulder main groove 5 and the crown main groove 7. The second middle land portion 12 is divided between the second shoulder main groove 6 and the crown main groove 7. The first shoulder land portion 13 is divided between the first shoulder main groove 5 and the first tread end Te1. The second shoulder land portion 14 is divided between the second shoulder main groove 6 and the second tread end Te2.

FIG. 2 shows an enlarged view of the first middle land portion 11 and the second middle land portion 12. As shown in FIG. 2, the width W1 in the tire axial direction of the first middle land portion 11 and the width W2 in the tire axial direction of the second middle land portion 12 are, for example, 0.10 of the tread width TW. It is desirable that it is ~ 0.25 times.

A plurality of first middle lateral grooves 16 are provided in the first middle land portion 11. The first middle lateral groove 16 completely crosses the first middle land portion 11. The second middle land portion 12 is provided with a plurality of second middle lateral grooves 17. The second middle lateral groove 17 completely crosses the second middle land portion 12. The groove width of the first middle lateral groove 16 and the groove width of the second middle lateral groove 17 are, for example, 0.10 to 0.20 times the groove width of the crown main groove 7.

FIG. 3 shows a sectional view taken along line AA of the first middle lateral groove 16 and the second middle lateral groove 17 of FIG. As shown in FIG. 3, at least one of the first middle lateral grooves 16 of the present invention includes a raised portion 18 having a raised bottom surface. Further, at least one of the second middle lateral grooves 17 includes a raised portion 19 having a raised bottom surface.

In FIG. 2, the raised portions 18 and 19 are colored in one of the first middle lateral grooves 16 and one of the second middle lateral grooves 17 for easy understanding. As shown in FIG. 2, the raised portions 18 and 19 cross the center position of the first middle land portion 11 or the second middle land portion 12 in the tire axial direction. The first middle lateral groove 16 and the second middle lateral groove 17 including the above-mentioned raised portion can effectively suppress the deformation of the first middle land portion 11 and the second middle land portion 12, and can exhibit excellent steering stability. As a preferred embodiment, in the present embodiment, each first middle lateral groove 16 and each second middle lateral groove 17 include a raised portion having the above configuration.

The first middle lateral groove 16 and the second middle lateral groove 17 can prevent the movement of air in the groove by the raised portion, and can suppress the pumping noise. Further, the first middle lateral groove 16 and the second middle lateral groove 17 having the raised portion are useful for maintaining the rigidity of each middle horizontal portion and enhancing the steering stability.

As shown in FIG. 3, the length L3 of the raised portion 18 of the first middle lateral groove 16 in the tire axial direction is larger than the length L4 of the raised portion 19 of the second middle lateral groove 17 in the tire axial direction. Such an arrangement of the lateral grooves can relatively increase the rigidity of the first middle land portion 11. Therefore, when the center of the contact patch moves to the first tread end Te1 side during turning, the steering response becomes linear and excellent steering stability can be obtained.

In a preferred embodiment, the length L3 of the raised portion 18 of the first middle lateral groove 16 is 1.05 to 1.25 times the length L4 of the raised portion 19 of the second middle lateral groove 17. Such a ridge helps to balance steering stability and ride comfort.

The length L3 of the raised portion 18 of the first middle lateral groove 16 in the tire axial direction is, for example, 0.30 to 0.80 times the width W1 of the first middle land portion 11 in the tire axial direction (shown in FIG. 2). is there. The length L4 of the raised portion 19 of the second middle lateral groove 17 in the tire axial direction is, for example, 0.30 to 0.80 times the width W2 of the second middle land portion 12 in the tire axial direction (shown in FIG. 2). is there.

The depth d2 of the raised portions 18 and 19 is, for example, preferably 0.10 times or more, more preferably 0.20 times or more, preferably 0.60 times or less, more than the depth d1 of the crown main groove 7. It is preferably 0.50 times or less. Further, with respect to the first middle lateral groove 16 and the second middle lateral groove 17, the depth of the end portion in the tire axial direction is 0.30 to 0.80 times the depth d1 of the crown main groove 7. Such a first middle lateral groove 16 and a second middle lateral groove 17 can improve steering stability and riding comfort in a well-balanced manner.

As shown in FIG. 2, in the tread plan view, the first middle lateral groove 16 has the first convex portion 16a arranged on one side with respect to the groove reference straight line 16c connecting both ends of the groove center line, and the groove reference straight line. It is a curved groove including a second convex portion 16b arranged on the other side with respect to 16c. Similarly, the second middle lateral groove 17 is arranged on one side of the groove reference straight line 17c connecting both ends of the groove center line and on the other side of the groove reference straight line 17c. It is a curved groove including the second convex portion 17b. As a more desirable embodiment, the curved groove of the present embodiment is curved in an S shape.

In the present embodiment, in the first middle lateral groove 16, the entire central portion 16d in the tire axial direction is configured as the above-mentioned raised portion 18. Specifically, the first middle lateral groove 16 has a central portion 16d (raised portion 18) extending diagonally across the center position of the first middle land portion 11 in the tire axial direction and a first outer side connected to both sides of the central portion 16d. It is a curved groove including a portion 16e and a second outer portion 16f. The first outer portion 16e extends from one end of the central portion 16d at an angle smaller than that of the central portion 16d with respect to the tire axial direction. The second outer portion 16f extends from the other end of the central portion 16d at an angle smaller than that of the central portion 16d with respect to the tire axial direction. In the present embodiment, the first outer portion 16e is arranged on the first tread end Te1 side of the central portion 16d, and the second outer portion 16f is arranged on the second tread end Te2 side of the central portion 16d. ..

Similarly, in the second middle lateral groove 17, the entire central portion 17d in the tire axial direction is configured as the above-mentioned raised portion 19. Specifically, the second middle lateral groove 17 has a central portion 17d (raised portion 19) extending diagonally across the center position of the second middle land portion 12 in the tire axial direction and a first outer side connected to both sides of the central portion 17d. It is a curved groove including a portion 17e and a second outer portion 17f. The first outer portion 17e extends from one end of the central portion 17d at an angle smaller than that of the central portion 17d with respect to the tire axial direction. The second outer portion 17f extends from the other end of the central portion 17d at an angle smaller than that of the central portion 17d with respect to the tire axial direction. In the present embodiment, the first outer portion 17e is arranged on the first tread end Te1 side of the central portion 17d, and the second outer portion 17f is arranged on the second tread end Te2 side of the central portion 17d. ..

In each of the first middle lateral grooves 16 of the present embodiment, for example, the groove reference straight line 16c is inclined in the first direction (downward to the right in the present embodiment) with respect to the tire axial direction. Further, it is desirable that the raised portion 18 of the first middle lateral groove 16 is inclined in the first direction with respect to the tire axial direction. The angle θ1 of the raised portion 18 of the first middle lateral groove 16 with respect to the tire circumferential direction is larger than the angle of the groove reference straight line 16c of the first middle lateral groove 16 with respect to the tire axial direction. Specifically, the angle θ1 of the raised portion 18 of the first middle lateral groove 16 with respect to the tire axial direction is 5 to 40 °, more preferably 15 to 30 °.

In each of the second middle lateral grooves 17 of the present embodiment, for example, the groove reference straight line 17c is inclined in the second direction (upward to the right in the present embodiment) opposite to the first direction with respect to the tire axial direction. There is. Further, it is desirable that the raised portion 19 of the second middle lateral groove 17 is inclined in the second direction with respect to the tire axial direction. The angle θ2 of the raised portion 19 of the second middle lateral groove 17 with respect to the tire circumferential direction is larger than the angle of the groove reference straight line 17c of the second middle lateral groove 17 with respect to the tire axial direction. Specifically, the angle θ2 of the raised portion 19 of the second middle lateral groove 17 with respect to the tire axial direction is 20 to 60 °, more preferably 40 to 55 °.

In the present embodiment, the angle θ1 of the raised portion 18 of the first middle lateral groove 16 with respect to the tire axial direction is smaller than the angle θ2 of the raised portion 19 of the second middle lateral groove 17 with respect to the tire axial direction. As a result, the rigidity of the first middle land portion 11 in the tire axial direction is relatively increased, and the steering stability can be further improved.

In the first middle lateral groove 16, the length L3 of the raised portion 18 in the tire axial direction is from the length L5 of the first outer portion 16e in the tire axial direction and the length L6 of the second outer portion 16f in the tire axial direction. Is also big. Similarly, in the second middle lateral groove 17, the length L4 of the raised portion 19 in the tire axial direction is the length L7 of the first outer portion 17e in the tire axial direction and the length of the second outer portion 17f in the tire axial direction. It is larger than L8. By providing the above-mentioned configurations in each of the first middle lateral groove 16 and the second middle lateral groove 17, the rigidity of the first middle land portion 11 and the second middle land portion 12 is sufficiently increased, and excellent steering stability is achieved. Is demonstrated.

In the first middle lateral groove 16, the length L6 of the second outer portion 16f in the tire axial direction is 0.99 to 1.10 times the length L5 of the first outer portion 16e in the tire axial direction. In the present embodiment, in the first middle lateral groove 16, the length L6 of the second outer portion 16f is the same as the length L5 of the first outer portion 16e.

In the second middle lateral groove 17, it is desirable that the length L8 of the second outer portion 17f in the tire axial direction is larger than the length L7 of the first outer portion 17e in the tire axial direction. Specifically, it is desirable that the length L8 of the second outer portion 17f is, for example, 1.10 to 2.00 times the length L7 of the first outer portion 17e. As a result, the rigidity of the first tread end Te1 side of the second middle lateral groove 17 is increased, and the steering response during turning can be made more linear.

Further, by adopting the raised portions 18 and 19 as described above, the frequency bands of the pumping sound generated by the first middle lateral groove 16 and the pumping sound generated by the second middle lateral groove 17 can be made different, and thus these The pumping sound can be converted to white noise.

As shown in FIG. 2, it is desirable that the tire circumferential length L1 of the groove reference straight line 16c of the first middle lateral groove 16 is smaller than the tire circumferential length L2 of the groove reference straight line 17c of the second middle lateral groove 17. .. Such an arrangement of the lateral grooves can relatively increase the rigidity of the first middle land portion 11 in the tire axial direction. Therefore, when the center of the contact patch moves to the first tread end Te1 side during turning, the steering response becomes linear and excellent steering stability can be obtained.

It is desirable that the tire circumferential length L1 of the groove reference straight line 16c of the first middle lateral groove 16 is 0.20 to 0.40 times the tire circumferential length L2 of the groove reference straight line 17c of the second middle lateral groove 17. .. Such an arrangement of the lateral grooves can make the steering response during turning more linear.

It is desirable that the tire circumferential length L1 of the groove reference straight line 16c of the first middle lateral groove 16 is smaller than, for example, one pitch length P1 of the first middle lateral groove 16 in the tire circumferential direction. Specifically, the tire circumferential length L1 of the groove reference straight line 16c of the first middle lateral groove 16 is, for example, 0.05 to 0.20 times the tire circumferential length P1 of the first middle lateral groove 16 in the tire circumferential direction. Is. Such an arrangement of the first middle lateral groove 16 is useful for suppressing uneven wear of the first middle land portion 11.

From the same viewpoint, it is desirable that the tire circumferential length L2 of the groove reference straight line 17c of the second middle lateral groove 17 is smaller than, for example, one pitch length P2 of the second middle lateral groove 17 in the tire circumferential direction. Specifically, the tire circumferential length L2 of the groove reference straight line 17c of the second middle lateral groove 17 is, for example, 0.35 to 0.50 times the tire circumferential length P2 of the second middle lateral groove 17 in the tire circumferential direction. Is. In the present embodiment, the 1-pitch length P2 of the second middle lateral groove 17 is the same as the 1-pitch length P1 of the first middle lateral groove 16.

The maximum distance L9 from the groove reference straight line 16c of the first middle lateral groove 16 to the groove edge is smaller than the distance L10 from the groove reference straight line 17c of the second middle lateral groove 17 to the groove edge. As a result, the rigidity of the first middle land portion 11 is relatively increased, and the above-mentioned effect can be further enhanced.

It is desirable that the first middle lateral groove 16 and the second middle lateral groove 17 are arranged so as to be smoothly continuous with each other via the crown main groove 7. In addition, in this specification, "two lateral grooves smoothly continue through a main groove" means a region in which one lateral groove extends along the length direction and the other lateral groove in the length direction. It means that the minimum separation distance in the tire circumferential direction in the main groove is less than 1.0 mm with respect to the region extended along the line. When the lateral groove is bent, the region shall extend while maintaining the curvature at the end of the lateral groove on the main groove side. As a more desirable embodiment, in the present embodiment, the region where the first middle lateral groove 16 is extended and the region where the second middle lateral groove 17 is extended overlap in the crown main groove 7 (that is, the minimum separation distance is the same). It is 0.).

The first middle land portion 11 includes a plurality of first middle blocks 21 divided into a plurality of first middle lateral grooves 16. The second middle land portion 12 includes a plurality of second middle blocks 22 divided into a plurality of second middle lateral grooves 17.

In the present embodiment, each of the first middle blocks 21 is, for example, a smoothing block having no groove or sipe on the tread surface. In addition, in this specification, a "sipe" means a notch having a width of less than 1.5 mm.

Each of the second middle blocks 22 is provided with a second middle sipe 23 that extends from the second shoulder main groove 6 and is interrupted within the second middle block 22. The second middle sipe 23 of the present embodiment has a width of, for example, 0.5 to 1.0 mm. Such a first middle block 21 and a second middle block 22 can relatively increase the rigidity of the first middle land portion 11, linearize the steering response during turning, and thus improve the steering stability.

It is desirable that the length L11 of the second middle sipe 23 in the tire axial direction is, for example, 0.20 to 0.80 times the width W2 of the second middle land portion 12 in the tire axial direction. Such a second middle sipe 23 is useful for improving steering stability and riding comfort in a well-balanced manner.

It is desirable that the region where the raised portion 19 of the second middle lateral groove 17 extends in the tire circumferential direction overlaps with the second middle sipe 23. Such a second middle sipe 23 can reduce the hitting sound when the second middle land portion 12 touches the ground and improve the noise performance.

The maximum depth of the second middle sipe 23 is, for example, 0.99 to 1.10 times the depth of the raised portion 19 of the second middle lateral groove 17. In the present embodiment, the maximum depth of the second middle sipe 23 is the same as the depth of the raised portion 19 of the second middle lateral groove 17. Such a second middle sipe 23 is useful for suppressing uneven wear of the second middle land portion 12.

FIG. 4 shows an enlarged view of the first shoulder land portion 13. As shown in FIG. 4, the first shoulder land portion 13 is provided with a plurality of first shoulder lateral grooves 25 that completely cross the first shoulder land portion 13. The groove width of the first shoulder lateral groove 25 is, for example, 0.35 to 0.50 times the groove width of the first shoulder main groove 5.

Each of the first shoulder lateral grooves 25 is inclined in the second direction, for example. The angle θ3 of the first shoulder lateral groove 25 with respect to the tire axial direction is, for example, 5 to 15 °.

In at least one of the first shoulder lateral grooves 25, the end on the first shoulder main groove 5 side is provided at a position different from the end on the first shoulder main groove 5 side of the first middle lateral groove 16 in the tire circumferential direction. It is desirable to have. Further, the distance L12 (the distance between the groove center lines) in the tire circumferential direction between the end portion of the first shoulder lateral groove 25 and the end portion of the first middle lateral groove 16 is, for example, the first shoulder lateral groove 25. It is desirable that the length of one pitch in the tire circumferential direction is 0.35 times or less of P3. As a result, the pumping sound when the intersection of the first shoulder lateral groove 25 and the first shoulder main groove 5 touches the ground can be reduced.

FIG. 5 shows a sectional view taken along line BB of the first shoulder lateral groove 25 of FIG. As shown in FIG. 5, it is desirable that at least one of the first shoulder lateral grooves 25 includes a shallow bottom portion 26 having a raised bottom surface in a region including an end portion on the first shoulder main groove 5 side. Such a first shoulder lateral groove 25 increases the rigidity of the first shoulder land portion 13 and thus improves the steering stability.

The length L13 of the shallow bottom portion 26 of the first shoulder lateral groove 25 in the tire axial direction is, for example, 0.20 to 0.30 times the width W3 of the first shoulder lateral groove 25 in the tire axial direction (shown in FIG. 4). is there. In a more desirable embodiment, the length L13 of the shallow bottom portion 26 of the first shoulder lateral groove 25 in the tire axial direction is, for example, the length L3 of the raised portion 18 of the first middle lateral groove 16 (shown in FIG. 3) and the second. It is smaller than the length L4 (shown in FIG. 3) of the raised portion 19 of the middle lateral groove 17. Such a first shoulder lateral groove 25 prevents the rigidity of the first shoulder land portion 13 from being excessively increased, and helps to improve steering stability and ride comfort in a well-balanced manner.

FIG. 6 shows an enlarged view of the second shoulder land portion 14. As shown in FIG. 6, the second shoulder land portion 14 is provided with, for example, a second shoulder lateral groove 31, a connecting sipe 32, and a non-transverse narrow groove 33.

The second shoulder lateral groove 31 extends inward in the tire axial direction from the second tread end Te2 and has a break end 31a in the land portion 14 of the second shoulder, for example. The length L14 of the second shoulder lateral groove 31 in the tire axial direction is, for example, 0.50 to 0.70 times the width W4 of the second shoulder land portion 14 in the tire axial direction. The groove width of the second shoulder lateral groove 31 is, for example, 0.30 to 0.50 times the groove width of the second shoulder main groove 6.

The connecting sipe 32 extends from the interrupted end 31a of the second shoulder lateral groove 31 to the second shoulder main groove 6. The length L15 of the connecting sipe 32 in the tire axial direction is, for example, 0.30 to 0.50 times the width W4 of the second shoulder land portion 14 in the tire axial direction. The second shoulder lateral groove 31 and the connecting sipe 32 can maintain the rigidity of the second shoulder land portion 14 and exhibit excellent steering stability. Further, the second shoulder lateral groove 31 and the connecting sipe 32 have a small pumping sound and can be expected to improve the noise performance.

FIG. 7 shows a sectional view taken along line CC of the second shoulder lateral groove 31 and the connecting sipe 32 of FIG. As shown in FIG. 7, the second shoulder lateral groove 31 has, for example, an inclined bottom surface 31b extending obliquely with respect to the tire axial direction at the end on the second shoulder main groove 6 side. As a result, it is possible to prevent the formation of a portion where the rigidity of the second shoulder land portion 14 suddenly changes.

The connecting sipe 32 includes, for example, a first portion 32a, a second portion 32b, and a third portion 32c having different depths. The first portion 32a is connected to the second shoulder lateral groove 31. The second portion 32b is connected to the second shoulder main groove 6 side of the first portion 32a and has a depth larger than that of the first portion 32a. The third portion 32c is connected to the second shoulder main groove 6 side of the second portion 32b, and has a depth smaller than that of the first portion 32a and the second portion 32b. Such a connecting sipe 32 can appropriately relax the rigidity of the second shoulder land portion 14, and can improve the steering stability and the riding comfort in a well-balanced manner.

It is desirable that the depth of the first portion 32a and the second portion 32b of the connecting sipe 32 is larger than, for example, the depth of the raised portion 19 of the second middle lateral groove 17. It is desirable that the depth of the third portion 32c of the connecting sipe 32 is smaller than the depth of the raised portion 19 of the second middle lateral groove 17. Such a connecting sipe 32 is useful for suppressing uneven wear of the second shoulder land portion 14.

As shown in FIG. 6, it is desirable that the connecting sipe 32 is arranged so as to be smoothly continuous with the second middle sipe 23 via the second shoulder main groove 6.

The non-transverse groove 33 extends from, for example, the second shoulder main groove 6 and is interrupted in the second shoulder land portion 14. The length L16 of the non-crossing groove 33 in the tire axial direction is, for example, 0.50 to 0.65 times the width W4 of the second shoulder land portion 14 in the tire axial direction. Such a non-transverse narrow groove 33 helps to improve noise performance while maintaining steering stability.

In a more desirable embodiment, the tire axial length L16 of the non-transverse groove 33 is preferably larger than the tire axial length L15 of the connecting sipe 32. Such a non-crossing narrow groove 33 effectively relaxes the rigidity of the second shoulder land portion 14, and exhibits excellent riding comfort.

It is desirable that the non-transverse narrow groove 33 is arranged so as to be smoothly continuous with the second middle lateral groove 17 via the second shoulder main groove 6, for example. Since such a non-crossing narrow groove 33 is likely to open together with the second middle lateral groove 17 when the land portion touches the ground, the tapping sound when the second middle land portion 12 and the second shoulder land portion 14 touch the ground is reduced. can do.

FIG. 8 shows a sectional view taken along line DD of the non-transverse groove 33 of FIG. As shown in FIG. 8, the non-transverse groove 33 is arranged, for example, in the opening 33a arranged on the tread side of the land portion and inside the opening 33a in the tire radial direction, and has a width smaller than that of the opening 33a. It has a narrow portion 33b of. The width W5 of the narrow portion 33b is, for example, 0.5 to 1.0 mm. Such a non-transverse narrow groove 33 can obtain the above-mentioned effect without causing an excessive decrease in rigidity of the second shoulder land portion 14.

As shown in FIG. 1, each of the above-described configurations relatively increases the rigidity of the first middle land portion 11 and the first shoulder land portion 13. As a result, a tire having a large self-aligning torque (hereinafter, may be referred to as "SAT") can be obtained. For example, when tires with a large SAT are mounted on all wheels of a passenger car, the cornering power of the front wheels (hereinafter, may be referred to as "CP") is relatively reduced by the SAT, and the CP of the front wheels and the rear wheels are reduced. The CP approaches. Therefore, the passenger car in which the tires of the present embodiment are mounted on all wheels shifts to a neutral turning state in which the cornering force of the front wheels and the cornering force of the rear wheels are substantially balanced when the steering angle is given to the front wheels. It is easy and can demonstrate excellent steering stability.

Although the tire of one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-mentioned specific embodiment, and can be modified into various embodiments.

A tire of size 205 / 55R16 having the basic pattern of FIG. 1 and having the raised portions shown in FIG. 3 arranged in the first middle lateral groove and the second middle lateral groove was prototyped. As a comparative example, the length of the raised portion arranged in the first middle lateral groove in the tire axial direction and the length of the raised portion arranged in the second middle lateral groove in the tire axial direction, which have the basic pattern of FIG. A tire with the same is prototyped. The length of the raised portion of the first middle lateral groove in the comparative example in the tire axial direction is the same as the length of the raised portion of the first middle lateral groove shown in FIG. 3 in the tire axial direction. The steering stability and noise performance of each test tire were tested. The common specifications and test methods for each test tire are as follows.
Mounting rim: 16 x 6.5J
Tire internal pressure: front wheels 200kPa, rear wheels 200kPa
Test vehicle: Displacement 1600cc, front-wheel drive vehicle Tire mounting position: All wheels

<Maneuvering stability>
The test vehicle traveled on a dry road surface, and the steering stability at low speed (40 to 80 km / h) and high speed (100 to 120 km / h) was evaluated by the driver's sensuality. The result is a score with a comparative example of 100, and the larger the value, the better the steering stability.

<Noise performance>
The test vehicle traveled on a dry road surface including irregularities at 40 to 100 km / h, and the maximum sound pressure of noise (100 to 350 Hz) in the vehicle at this time was measured. The result is an index with the sound pressure of the comparative example as 100, and the smaller the value, the smaller the noise inside the vehicle and the better the noise performance.
The test results are shown in Table 1.

As a result of the test, it was confirmed that the tires of the examples had improved steering stability and noise performance.

2 Tread part 3 Main groove 4 Land part 5 1st shoulder main groove 6 2nd shoulder main groove 7 Crown main groove 11 1st middle land part 12 2nd middle land part 16 1st middle horizontal groove 17 2nd middle horizontal groove 18 raised part 19 Raised part Te1 1st tread end Te2 2nd tread end

Claims (10)

A tire with a tread that is oriented to be mounted on a vehicle.
The tread portion has a tire circumference between a first tread end located on the outside of the vehicle when mounted on the vehicle, a second tread end located on the inside of the vehicle when mounted on the vehicle, and the first tread end and the second tread end. It has a plurality of main grooves extending continuously in the direction and a plurality of land portions divided into the main grooves.
The main groove includes a first shoulder main groove arranged between the first tread end and the tire equator, a second shoulder main groove arranged between the second tread end and the tire equator, and the above. Includes a crown main groove arranged between the first shoulder main groove and the second shoulder main groove.
The land portion is divided into a first middle land portion divided between the first shoulder main groove and the crown main groove, and a second divided between the second shoulder main groove and the crown main groove. Including middle land
The first middle land portion is provided with a plurality of first middle lateral grooves completely crossing the first middle land portion.
The second middle land portion is provided with a plurality of second middle lateral grooves that completely cross the second middle land portion.
At least one of the first middle lateral grooves and at least one of the second middle lateral grooves has a raised portion having a raised bottom surface.
The raised portion crosses the center position of the first middle land portion or the second middle land portion in the tire axial direction.
The length of the raised portion of the first middle lateral groove in the tire axial direction is larger than the length of the raised portion of the second middle lateral groove in the tire axial direction.
tire. The first middle lateral groove according to claim 1, wherein the length of the raised portion of the first middle lateral groove in the tire axial direction is 1.05 to 1.25 times the length of the raised portion of the second middle lateral groove in the tire axial direction. Tires. The depth of the raised portion of the first middle lateral groove and the depth of the raised portion of the second middle lateral groove are 0.10 to 0.60 times the depth of the crown main groove, respectively. The tire according to claim 1 or 2. In the tread plan view, each of the first middle lateral groove and the second middle lateral groove is
The raised portion extending inclining with respect to the tire axial direction,
A first outer portion extending from one end of the raised portion at an angle smaller than that of the raised portion with respect to the tire axial direction,
The tire according to any one of claims 1 to 3, which is a curved groove including a second outer portion extending from the other end portion of the raised portion at an angle smaller than the raised portion with respect to the tire axial direction. The tire according to claim 4, wherein the curved groove is bent in an S shape. In the first middle lateral groove and the second middle lateral groove,
The tire according to claim 4 or 5, wherein the length of the raised portion in the tire axial direction is larger than the length of the first outer portion in the tire axial direction and the length of the second outer portion in the tire axial direction. .. In the second middle lateral groove
The tire according to any one of claims 4 to 6, wherein the length of the second outer portion in the tire axial direction is larger than the length of the first outer portion in the tire axial direction. In the second middle lateral groove
The tire according to any one of claims 4 to 7, wherein the length of the second outer portion in the tire axial direction is 1.10 to 2.00 times the length of the first outer portion in the tire axial direction. .. In the second middle lateral groove
The tire according to claim 8, wherein the second outer portion is arranged on the second tread end side of the raised portion. In the first middle lateral groove
The tire according to any one of claims 4 to 9, wherein the length of the first outer portion in the tire axial direction is the same as the length of the second outer portion in the tire axial direction.

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