tire

Abstract

The arrangement of chamfered and non-chamfered sipes is optimized to improve wet braking performance and wet handling stability. [Solution] In the tire 1, the first and second middle sections have a plurality of sipe units composed of non-chamfered sipes and chamfered sipes, and among the chamfered sipes located on both sides of the non-chamfered sipe in the tire circumferential direction, the chamfered sipe on the side closer to the non-chamfered sipe is designated as the adjacent chamfered sipe, and the combination of the non-chamfered sipe and the adjacent chamfered sipe constitutes a sipe unit, and the rib width W1 of the first middle section and the rib width W2 of the second middle section are W1

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] A technique is known for effectively improving wet (hereinafter, WET) braking performance by arranging a sipe unit combining chamfered sipes and non-chamfered sipes (for example, Patent Document 1, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, due to insufficient rigidity of the tread surface, the sipes may collapse, etc., resulting in insufficient WET braking performance and WET handling stability performance. The present disclosure has been made in view of the above, and its object is to optimize the arrangement of chamfered sipes and non-chamfered sipes and improve WET braking performance and WET handling stability performance.

Means for Solving the Problems

[0005] In order to solve the above-described problems and achieve the object, a tire according to an aspect of the present disclosure includes one or more center main grooves, a pair of shoulder main grooves provided outside the center main groove in the tire width direction, and a pair of shoulder lands and first and second middle lands partitioned by these main grooves. The first and second middle lands each have a plurality of chamfered sipes having a sip part and a chamfered part, and a plurality of non-chamfered sipes having no chamfered part. The chamfered sipes and the non-chamfered sipes are alternately arranged in the tire circumferential direction. The first and second middle lands each have a plurality of sipes units composed of the non-chamfered sipes and the chamfered sipes. Among the chamfered sipes located on both sides in the tire circumferential direction of the non-chamfered sipes, the chamfered sipes closer to the non-chamfered sipes are defined as proximity chamfered sipes. A combination of the non-chamfered sipes and the proximity chamfered sipes forms the sipes unit. The rib width W1 of the first middle land and the rib width W2 of the second middle land have a relationship of W1 < W2. The interval D1 between the non-chamfered sipes and the chamfered sipes of the sipes unit in the first middle land has a relationship of D1 < D2 with respect to the interval D2 between the non-chamfered sipes and the chamfered sipes of the sipes unit in the second middle land.

Advantages of the Invention

[0006] According to the present disclosure, the arrangement of the chamfered sipes and the non-chamfered sipes can be optimized, the block rigidity can be enhanced, the chamfering collapse of the sipes can be suppressed, and the WET braking performance and the WET handling stability performance can be improved.

Brief Description of the Drawings

[0007] [Figure 1] FIG. 1 is a meridional cross-sectional view of a pneumatic tire according to the present embodiment. [Figure 2] FIG. 2 is a plan view of a tread portion of a pneumatic tire according to the present embodiment. [Figure 3] FIG. 3 is an enlarged view showing a part of the first middle land in FIG. 2. [Figure 4]Figure 4 is an enlarged view of a portion of the second middle section of the track and field course in Figure 2. [Figure 5] Figure 5 is a schematic diagram showing a cross-section of section AA in Figure 3. [Figure 6] Figure 6 schematically shows a cross-section of section AA in Figure 3 in a grounded state. [Figure 7] Figure 7 shows a modified version of the first middle-distance track and field section. [Figure 8] Figure 8 shows a modified version of the second middle-distance track and field section. [Figure 9A] Figure 9A is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9B] Figure 9B is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9C] Figure 9C is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9D] Figure 9D is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9E] Figure 9E is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9F] Figure 9F is a chart showing the results of the performance test of the tire according to this embodiment. [Figure 9G] Figure 9G is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9H] Figure 9H is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9I] Figure 9I is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9J] Figure 9J is a chart showing the results of a performance test of the tire according to this embodiment. [Figure 9K] Figure 9K is a chart showing the results of a performance test of the tire according to this embodiment. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In the description of each of the following embodiments, the same or equivalent components as those in other embodiments are denoted by the same reference numerals, and the description thereof is simplified or omitted. The present invention is not limited by each embodiment. Further, the components of each embodiment include those that can be replaced and are easy for those skilled in the art, or those that are substantially the same. Also, the configurations described below can be combined as appropriate. Further, omissions, substitutions, or changes in the configuration can be made without departing from the gist of the invention.

[0009] [Pneumatic tire] In the following description, as an example of the tire according to the present disclosure, the pneumatic tire 1 will be described. The pneumatic tire 1, which is an example of the tire according to the present disclosure, can be filled with air, an inert gas such as nitrogen, and other gases.

[0010] FIG. 1 is a meridian cross-sectional view of the pneumatic tire according to the present embodiment. FIG. 2 is a plan view of the tread portion of the pneumatic tire 1 according to the present embodiment. The pneumatic tire 1 according to the present embodiment has an annular structure centered on the tire rotation axis. FIG. 1 shows a one-sided region in the tire radial direction. Also, FIG. 1 shows a radial tire for a passenger car as an example of the pneumatic tire.

[0011] In the following description, the tire radial direction refers to the direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1. The inner side in the tire radial direction refers to the side facing the rotation axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the rotation axis in the tire radial direction. Also, the tire circumferential direction refers to the circumferential direction around the rotation axis as the central axis. Further, the tire width direction refers to the direction parallel to the rotation axis. The inner side in the tire width direction refers to the side facing the tire equatorial plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL coincides with the center line in the tire width direction, which is the central position in the tire width direction of the pneumatic tire 1. The tire equator line refers to a line on the tire equatorial plane CL and along the tire circumferential direction of the pneumatic tire 1. In this embodiment, the same symbol "CL" as that of the tire equatorial plane is used.

[0012] As shown in FIG. 1, the pneumatic tire 1 of this embodiment has a tread portion 2, shoulder portions 3 on both sides thereof, and sidewall portions 4 and bead portions 5 that are sequentially continuous from each shoulder portion 3. Further, this pneumatic tire 1 includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

[0013] The tread portion 2 is made of a rubber material (tread rubber), is exposed on the outermost side in the tire radial direction of the pneumatic tire 1, and its outer peripheral surface forms the contour of the pneumatic tire 1. The outer peripheral surface of the tread portion 2 is mainly a surface that can contact the road surface during running and is configured as a ground contact surface 10. [[ID=]]

[0014] The shoulder portion 3 is the outermost part of the tread portion 2 in the tire width direction. The sidewall portion 4 is the outermost exposed part in the tire width direction of the pneumatic tire 1. The bead portion 5 has a bead core 15 and a bead filler 16. The bead core 15 is formed by winding a bead wire, which is a steel wire, into a ring shape. The bead filler 16 is a rubber material placed in the space formed when the tire width direction end of the carcass layer 6 is folded back at the position of the bead core 15.

[0015] The carcass layer 6 is formed by folding each end in the tire width direction from the inside to the outside in the tire width direction by a pair of bead cores 15, and wrapping around the tire circumferentially in a toroidal shape to form the tire's skeleton. This carcass layer 6 consists of multiple carcass cords (not shown) arranged in parallel at an angle in the tire circumferential direction that aligns with the tire meridian direction, and these cords are covered with a coating rubber. The carcass cords are made of organic fibers such as polyester, rayon, or nylon. This carcass layer 6 is provided in at least one layer.

[0016] The belt layer 7 has a multilayer structure consisting of at least two belts 7a and 7b stacked together. It is positioned on the outer circumference of the carcass layer 6 in the tread portion 2, on the radial side of the tire, and covers the carcass layer 6 in the circumferential direction of the tire. The belts 7a and 7b consist of multiple cords (not shown) arranged side by side at a predetermined angle (e.g., 20° to 30°) with respect to the circumferential direction of the tire, which are covered with a coating rubber. The cords are made of, for example, steel or organic fibers such as polyester, rayon, or nylon. The overlapping belts 7a and 7b are arranged so that their cords intersect.

[0017] The belt reinforcement layer 8 is positioned on the outer circumference of the belt layer 7, in the tire radial direction, and covers the belt layer 7 in the tire circumferential direction. The belt reinforcement layer 8 consists of multiple cords (not shown) arranged in parallel in the tire width direction, substantially parallel to the tire circumferential direction, and covered with coated rubber. The cords are made of, for example, steel, or organic fibers such as polyester, rayon, or nylon, and the angle of the cords is within ±5° with respect to the tire circumferential direction. The belt reinforcement layer 8 shown in Figure 1 is positioned to cover the entire belt layer 7. The configuration of the belt reinforcement layer 8 is not limited to the above, and although not explicitly shown in the figure, it may be configured to cover only the tire width direction end of the belt layer 7, or it may have, for example, two reinforcement layers, where the inner reinforcement layer in the tire radial direction is formed to be larger in the tire width direction than the belt layer 7 and is positioned to cover the entire belt layer 7, and the outer reinforcement layer in the tire radial direction is positioned to cover only the tire width direction end of the belt layer 7, or it may have, for example, two reinforcement layers, where each reinforcement layer is positioned to cover only the tire width direction end of the belt layer 7. In other words, the belt reinforcement layer 8 overlaps at least the tire widthwise end of the belt layer 7. Furthermore, the belt reinforcement layer 8 is provided by, for example, wrapping a strip material with a width of about 10 mm around the tire in the circumferential direction.

[0018] The internal structure of the pneumatic tire 1 described above is a typical example, but the internal structure is not limited to this example.

[0019] The pneumatic tire 1 of this embodiment has a specified mounting direction relative to the vehicle. That is, when the pneumatic tire 1 of this embodiment is mounted on a vehicle, its orientation relative to the outside and inside of the vehicle is specified in the tire width direction. The orientation is not explicitly shown in the figure, but is indicated, for example, by an indicator provided on the sidewall portion 4. Therefore, when mounted on a vehicle, the side facing outwards from the vehicle becomes the outside of the vehicle, and the side facing inwards from the vehicle becomes the inside of the vehicle. Note that the designation of outside and inside of the vehicle is not limited to when mounted on a vehicle. For example, when assembled on a rim, the orientation of the rim relative to the outside and inside of the vehicle is determined in the tire width direction. Therefore, when the pneumatic tire 1 is assembled on a rim, its orientation relative to the outside and inside of the vehicle is specified in the tire width direction.

[0020] [Tread area] The contact surface 10 of the tread portion 2 has four circumferential main grooves 20 arranged in the tire width direction, which extend in the circumferential direction of the tire and are continuous throughout the entire circumference of the tire.

[0021] The circumferential main groove 20 is a groove that is required to display a wear indicator as specified by JATMA, and has a groove width of 3.0 mm or more and a groove depth of 6.0 mm or more.

[0022] The groove width, sipe width, and tread width described below are measured as the maximum value of the dimensions in the tire width direction at both groove opening ends that open to the contact surface 10, under no-load conditions (specified load = 0) with the pneumatic tire 1 mounted on a specified rim and filled with the specified internal pressure. In configurations where notches or chamfers are formed on the groove opening edges, the groove width is measured including the notches or chamfers, with the groove opening ends being the outer edges of the notches or chamfers. The groove depth and sipe depth are measured as the maximum value of the dimensions from the contact surface 10 to the bottom of the groove under no-load conditions (specified load = 0) with the pneumatic tire 1 mounted on a specified rim and filled with the specified internal pressure.

[0023] A specified rim is a "standard rim" as defined by JATMA, a "Design Rim" as defined by TRA, or a "Measuring Rim" as defined by ETRTO. The specified internal pressure is the "maximum air pressure" as defined by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or the "INFLATION PRESSURES" as defined by ETRTO. The specified load is the "maximum load capacity" as defined by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or the "LOAD CAPACITY" as defined by ETRTO.

[0024] The circumferential main grooves 20 are arranged in pairs on the outer side in the tire width direction, with the tire equatorial plane CL as the boundary. On the inside of the vehicle, the circumferential main grooves 20 closer to the tire equatorial plane CL are called the inner center main groove (also called the center main groove) 21, and the circumferential main grooves 20 on the inner side in the tire width direction of the inner center main groove 21 are called the inner shoulder main groove (also called the shoulder main groove) 23. On the outside of the vehicle, the circumferential main grooves 20 closer to the tire equatorial plane CL are called the outer center main groove (also called the center main groove) 22, and the circumferential main grooves 20 on the outer side in the tire width direction of the outer center main groove 22 are called the outer shoulder main groove (also called the shoulder main groove) 24. The center land area 31 is partitioned by the inner center main groove 21 and the outer center main groove 22. In other words, the tread portion 2 comprises one or more center main grooves, a pair of shoulder main grooves provided on the outer side of the center main groove in the tire width direction, a center land portion 31 partitioned by these main grooves, a first middle land portion 32, a second middle land portion 33, and a pair of shoulder land portions 34, 35.

[0025] In Figures 1 and 2, the symbol "T" indicates the tire contact point. The tire contact point T is defined as the position of the maximum width in the axial direction of the tire at the contact surface between the tire and the flat plate when the tire is mounted on a specified rim, subjected to a specified internal pressure, and placed perpendicular to the flat plate in a stationary state, with a load corresponding to a specified load applied.

[0026] [Center Track and Field Club] Referring to Figure 2, the center land portion 31 is positioned to cross the tire equatorial plane CL. The center land portion 31 has sipes 71. Multiple sipes 71 are provided periodically in the circumferential direction of the tire. The sipes 71 extend in the circumferential direction and the width direction of the tire. One end of the sipes 71 communicates with the center main groove 21. The other end of the sipes 71 terminates at the center land portion 31 without communicating with any groove. The sipes 71 are notches formed in the tread surface and close when the tire makes contact with the ground. The same applies to each sipe or sipe portion described later.

[0027] [Middle Track and Field Club] The first middle section 32 has multiple chamfered sipes 43 and non-chamfered sipes 42. The chamfered sipes 43 and non-chamfered sipes 42 are arranged alternately in the circumferential direction of the tire. The non-chamfered sipes 42 do not have a chamfered portion. The chamfered sipes 43 have a sipe portion 431 and a chamfered portion 430. The chamfered sipes 43 are configured such that the chamfered portion 430 is connected to the sipe portion 431.

[0028] Furthermore, the first middle section 32 has a shallow bottom section 41. The shallow bottom section 41 has a V-shape with its top 410 facing in the circumferential direction of the tire. The shallow bottom section 41 of the first middle section 32 is connected to a non-chamfered sipe 42.

[0029] In the first middle section 32, a sipe unit 40 is defined, consisting of a non-chamfered sipe 42 and a chamfered sipe 43. Of the chamfered sipes 43 located on both sides of the non-chamfered sipe 42 in the tire circumferential direction, the chamfered sipe 43 closer to the non-chamfered sipe 42 is defined as the adjacent chamfered sipe, and the combination of the non-chamfered sipe 42 and the adjacent chamfered sipe constitutes the sipe unit 40. The first middle section 32 has multiple sipe units 40. Multiple sipe units 40 are provided in the tire circumferential direction in the first middle section 32.

[0030] The second middle section 33 has multiple chamfered sipes 53 and non-chamfered sipes 52. The chamfered sipes 53 and non-chamfered sipes 52 are arranged alternately in the circumferential direction of the tire. The non-chamfered sipes 52 do not have a chamfered portion. The chamfered sipes 53 have a sipe portion 531 and a chamfered portion 530. The chamfered sipes 53 are configured such that the chamfered portion 530 is connected to the sipe portion 531.

[0031] Furthermore, the second middle section 33 has a shallow bottom section 51. The shallow bottom section 51 has a V-shape with its top 510 facing in the circumferential direction of the tire. The shallow bottom section 51 of the second middle section 33 is connected to the non-chamfered sipe 52.

[0032] In the second middle section 33, a sipe unit 50 is defined, consisting of a non-chamfered sipe 52 and a chamfered sipe 53. Of the chamfered sipes 53 located on both sides of the non-chamfered sipe 52 in the tire circumferential direction, the chamfered sipe 53 closer to the non-chamfered sipe 52 is defined as the adjacent chamfered sipe, and the combination of the non-chamfered sipe 52 and the adjacent chamfered sipe constitutes the sipe unit 50. The second middle section 33 has multiple sipe units 50. Multiple sipe units 50 are provided in the second middle section 33 in the tire circumferential direction.

[0033] [Shoulder Track and Field Club] The shoulder land portion 34 is provided on the outer side in the tire width direction of the first middle land portion 32. The shoulder land portion 34 has lug grooves 61, sipes 62, and circumferential fine grooves 63. The lug grooves 61 extend outward in the tire width direction from inside the tire contact end T of the shoulder land portion 34 and terminate outside the tire contact end T. A plurality of lug grooves 61 are provided in the tire circumferential direction. The sipes 62 extend inward in the tire width direction from inside the tire contact end T of the shoulder land portion 34 and communicate with the shoulder main groove 23. A plurality of sipes 62 are provided in the tire circumferential direction. The circumferential fine grooves 63 extend in the tire circumferential direction while intersecting each of the lug grooves 61 and each of the sipes 62 within the shoulder land portion 34.

[0034] The shoulder land portion 35 is provided on the outer side in the tire width direction of the second middle land portion 33. The shoulder land portion 35 has lug grooves 64 and sipes 65. The lug grooves 64 extend outward in the tire width direction from inside the tire contact end T of the shoulder land portion 35 and terminate outside the tire contact end T. A plurality of lug grooves 64 are provided in the tire circumferential direction. The sipes 65 extend inward in the tire width direction from inside the tire contact end T of the shoulder land portion 35 and communicate with the shoulder main groove 24. A plurality of sipes 65 are provided in the tire circumferential direction.

[0035] Here, let the rib width (land portion width) of the first middle land portion 32 be W1. Let the rib width (land portion width) of the second middle land portion 33 be W2. At this time, the rib width W1 and the rib width W2 have a relationship of W1 < W2.

[0036] Also, let the distance between the non-relieved sipe 42 and the relieved sipe 43 of the sipe unit 40 in the first middle land part 32 be D1. The distance D1 is the distance along the tire circumferential direction between the center position of the opening of the non-relieved sipe 42 to the shoulder main groove 23 and the center position of the opening of the sipe part 431 of the relieved sipe 43 to the shoulder main groove 23. Let the distance between the non-relieved sipe 52 and the relieved sipe 53 of the sipe unit 50 in the second middle land part 33 be D2. The distance D2 is the distance along the tire circumferential direction between the center position of the opening of the non-relieved sipe 52 to the shoulder main groove 24 and the center position of the opening of the sipe part 531 of the relieved sipe 53 to the shoulder main groove 24. At this time, the distance D1 and the distance D2 have the relationship of D1 < D2.

[0037] For the land part with a narrow rib width (the first middle land part 32), since the block rigidity is low, by narrowing the sipe distance (distance D1) of the sipe unit 40, the land length between the sipe units 40 is ensured and the block rigidity is increased. On the other hand, for the land part with a wide rib width (the second middle land part 33), since the block rigidity is high, by widening the sipe distance (distance D2) of the sipe unit 50, the land length between the sipe units 50 is shortened and the block rigidity is decreased. By doing so, the block rigidity of the entire pattern of the tread part 2 can be made uniform. By doing so, while maintaining the effect of improving the WET braking performance by adopting the sipe unit, the dry (hereinafter, DRY) handling stability and the WET handling stability (hereinafter, may be referred to as DRY·WET handling stability) can be improved. In addition, when W1 < W2 and D1 > D2, the rigidity balance of the pattern becomes inappropriate, and there is a risk of causing a decrease in DRY·WET handling stability, which is not preferable.

[0038] The ratio W2 / W1 of the rib width W2 of the second middle land section 33 to the rib width W1 of the first middle land section 32 is preferably between 1.1 and 1.6. This range is optimal for maintaining the overall rigidity balance of the pattern. If the ratio W2 / W1 is greater than 1.6, the difference in rib rigidity becomes too large, resulting in insufficient improvement of DRY / WET handling stability, which is undesirable. If the ratio W2 / W1 is less than 1.1, the effect of changing the rib width (i.e., changing the distance between sipes) becomes insufficient, which is undesirable. More preferably, the ratio W2 / W1 is between 1.2 and 1.4.

[0039] The ratio of the spacing D2 to the spacing D1, D2 / D1, is preferably between 1.2 and 2.0. This range is optimal for achieving the improved wet performance effect of the close-proximity chamfered sipes and improving handling stability. If the ratio D2 / D1 is greater than 2.0, the distance between the sipes becomes too great, resulting in insufficient improvement in wet braking performance, which is undesirable. If the ratio D2 / D1 is less than 1.2, the effect of changing the distance between the sipes (changing the rib width) becomes insufficient, which is also undesirable. More preferably, the ratio D2 / D1 is between 1.3 and 1.6.

[0040] The ratio D1 / W1 of the spacing D1 to the rib width W1 is preferably 0.2 or more and 0.8 or less, and the ratio D2 / W2 of the spacing D2 to the rib width W2 is preferably 0.2 or more and 0.8 or less. The above range is optimal for exhibiting the effect of improving wet performance by closely spaced chamfered sipes and improving handling stability. If the ratio D1 / W1 and ratio D2 / W2 are less than 0.2, the distance between sipes is too narrow relative to the rib width, resulting in insufficient improvement of dry and wet handling stability, which is undesirable. If the ratio D1 / W1 and ratio D2 / W2 are greater than 0.8, the distance between sipes is too wide relative to the rib width, resulting in insufficient improvement of wet braking performance, which is undesirable. Furthermore, the ratios D1 / W1 and D2 / W2 are more preferably 0.3 or more and 0.6 or less.

[0041] It is preferable that the inclination angle θ1 of the chamfered sipe 43 of the sipe unit 40 in the first middle land section 32 with respect to the tire circumferential direction and the inclination angle θ2 of the chamfered sipe 53 of the sipe unit 50 in the second middle land section 33 have the relationship θ1 > θ2. By adjusting the inclination angle of the sipes in addition to the distance between the sipes, it is possible to achieve a higher level of balance between wet performance and handling stability. If the relationship of the inclination angles is θ1 ≤ θ2, the effect of improving dry and wet handling stability will be insufficient, which is undesirable. Note that the inclination angle θ1 only needs to be greater than the inclination angle θ2, and the inclination angle θ1 = 90 [deg] is also acceptable.

[0042] The inclination angles θ1 and θ2 are preferably between 30 degrees and 80 degrees. By setting the inclination angles of the chamfered sipes 43 and 53 within the above range, the effect of improving wet braking performance can be enhanced. If the inclination angles of the chamfered sipes 43 and 53 are less than 30 degrees or greater than 80 degrees, the effect of improving wet braking performance will be insufficient, which is undesirable. Furthermore, the inclination angles θ1 and θ2 are more preferably between 40 degrees and 75 degrees.

[0043] The difference between the inclination angles θ1 and θ2, θ1-θ2, is preferably between 5 degrees and 35 degrees. By keeping the difference in sipe inclination angles within this range, it is possible to achieve both improved wet braking performance and improved dry / wet handling stability. If the difference between the inclination angles θ1 and θ2, θ1-θ2, is less than 5 degrees or greater than 35 degrees, the effect of improving dry / wet handling stability will be insufficient, which is undesirable. Furthermore, the difference between the inclination angles θ1 and θ2, θ1-θ2, is more preferably between 10 degrees and 30 degrees.

[0044] The difference between the inclination angle θ1' and the inclination angle θ1 of the non-chamfered sipe 42 of the sipe unit 40 in the first middle track section 32, θ1-θ1', -10[deg]≦θ1-θ1'≦10[deg] The relationship is such that, and the difference between the inclination angle θ2' and the inclination angle θ2 of the non-chamfered sipe 52 of the sipe unit 50 in the second middle land section 33 with respect to the tire circumferential direction, θ2-θ2', -10[deg]≦θ2-θ2'≦10[deg] It is preferable that the following relationship exists: In other words, it is preferable that the chamfered sipe 43 and the non-chamfered sipe 42 of the sipe unit 40 are substantially parallel, and that the chamfered sipe 53 and the non-chamfered sipe 52 of the sipe unit 50 are substantially parallel. By having both of these substantially parallel, the effect of improving wet braking performance can be enhanced. If the difference in inclination angle θ1-θ1' or the difference θ2-θ2' is less than -10[deg] or greater than 10[deg], the effect of improving wet braking performance will be insufficient and undesirable. Furthermore, it is preferable that the difference in inclination angle θ1-θ1' and the difference θ2-θ2' be between -5[deg] and 5[deg].

[0045] In Figure 2, let X1 be the tire widthwise extension distance of the sipe portion 431 of the chamfered sipe 43 in the first middle land section 32. The ratio of distance X1 to rib width W1, X1 / W1, is: 0.40 ≤ X1 / W1 ≤ 0.90 It is preferable that the following relationship exists. Furthermore, let X2 be the tire width extension distance of the sipe portion 531 of the chamfered sipe 53 in the second middle land portion 33. The ratio of the distance X2 to the rib width W2, X2 / W2, is 0.40 ≤ X² / W² ≤ 0.90 It is preferable that the following relationship exists. By setting the tire width extension distance of the sipes within the above range, the effect of improving wet braking performance can be enhanced. If the ratio X1 / W1 or ratio X2 / W2 is less than 0.4, the effect of improving wet braking performance will be insufficient, and if it is greater than 0.9, the effect of improving dry handling stability will be insufficient, which is undesirable. Furthermore, for ratio X1 / W1 or ratio X2 / W2, it is more preferable to be 0.45 or more and 0.55 or less.

[0046] In Figure 2, it is preferable that the first middle section 32 is located on the inside of the vehicle mounting and the second middle section 33 is located on the outside of the vehicle mounting. By having a larger rib width (smaller main groove width) on the outside of the vehicle mounting and a smaller rib width (larger main groove width) on the inside of the vehicle mounting, it becomes possible to achieve a higher level of balance between dry handling stability and wet braking performance.

[0047] Here, Figure 3 is an enlarged view of a portion of the first middle land section 32 in Figure 2. Figure 4 is an enlarged view of a portion of the second middle land section 33 in Figure 2. Referring to Figures 2 and 3, as described above, the chamfered sipe 43 includes a sipe portion 431 and a chamfered portion 430. The chamfered portion 430 is provided only on the edge on the non-chamfered sipe 42 side of the edges on both sides of the sipe portion 431 that are perpendicular to the longitudinal direction. That is, the chamfered portion 430 is provided on the edge on the side closer to the non-chamfered sipe 42 of the edges on both sides of the sipe portion 431, and the chamfered portion is not provided on the edge on the side further from the non-chamfered sipe 42.

[0048] Figure 5 is a schematic diagram showing a cross-section of section AA in Figure 3. Referring to Figure 5, a chamfered sipe 43 is provided next to the non-chamfered sipe 42. The chamfered sipe 43 has a sipe portion 431 and a chamfered portion 430. The chamfered portion 430 is provided on the edge 431a of the sipe portion 431 that is closer to the non-chamfered sipe 42, and the edge 431b that is farther from the non-chamfered sipe 42 does not have a chamfered portion.

[0049] Figure 6 schematically shows a cross-section of section AA in Figure 3 in the contact state. As indicated by reference numeral 42a in Figure 6, the opening of the non-chamfered sipe 42 collapses and closes when the tire makes contact with the ground. In contrast, the chamfered sipe 43 has a chamfered portion 430 and therefore does not close when the tire makes contact with the ground. Thus, drainage performance can be maintained. In this way, by providing the chamfered portion 430 only on the side of the chamfered sipe 43 that is close to the non-chamfered sipe 42, wet braking performance can be effectively improved.

[0050] Similarly, referring to Figures 2 and 4, the chamfered sipe 53 includes a sipe portion 531 and a chamfered portion 530. Of the two edges of the sipe portion 531 perpendicular to the longitudinal direction, the chamfered portion 530 is provided only on the edge on the non-chamfered sipe 52 side. That is, of the two edges of the sipe portion 531, the chamfered portion 530 is provided on the edge closer to the non-chamfered sipe 52, and the edge further from the non-chamfered sipe 52 does not have a chamfered portion. By providing a chamfered portion only on the non-chamfered sipe side of the chamfered sipe 53, the wet braking performance can be effectively improved.

[0051] Furthermore, in Figure 3, the maximum width of the sipe portion 431 of the chamfered sipe 43 is denoted as Zs1, and the maximum width of the chamfered sipe 43 is denoted as Zm1. The ratio of the maximum width Zm1 to the maximum width Zs1, Zm1 / Zs1, is 2.00 ≤ Zm1 / Zs1 ≤ 6.00. The conditions are met, and the maximum width Zs1 is, 0.5 [mm] ≤ Zs1 ≤ 1.5 [mm] It is preferable that the following conditions be met.

[0052] Similarly, in Figure 4, let Zs2 be the maximum width of the sipe portion 531 of the chamfered sipe 53, and let Zm2 be the maximum width of the chamfered sipe 53. The ratio of the maximum width Zm2 to the maximum width Zs2, Zm2 / Zs2, is: 2.00 ≤ Zm² / Zs² ≤ 6.00 The conditions are met, and the maximum width Zs2 is, 0.5 [mm] ≤ Zs² ≤ 1.5 [mm] It is preferable that the following conditions be met.

[0053] To improve drainage at chamfered sipes 43 and 53, the above relationship is preferable. A maximum width Zs1 of less than 0.5 mm is undesirable as it results in insufficient drainage improvement. A maximum width Zs1 of greater than 1.5 mm is undesirable as it results in insufficient improvement of dry handling stability. Regarding the ratio Zm1 / Zs1, 2.00 ≤ Zm1 / Zs1 ≤ 4.00 The conditions are met, and for the maximum width Zs1, 0.5 [mm] ≤ Zs1 ≤ 1.0 [mm] It is preferable that it be so.

[0054] Furthermore, in Figure 3, the ratio Za1 / Zs1 of the distance Za1 from the non-chamfered sipe 42 to the sipe portion 431 of the chamfered sipe 43 in the sipe unit 40 to the maximum width Zs1 of the sipe portion 431 of the chamfered sipe 43 is preferably Za1 / Zs1 ≤ 30. If the ratio Za1 / Zs1 is greater than 30, the effect of improving wet braking performance will be insufficient, which is undesirable. More preferably, the ratio Za1 / Zs1 ≤ 20. It is preferable to satisfy the above relationship in order to improve drainage performance by proximity sipes.

[0055] For the distance Zb1 from the non-chamfered sipe 42 to the end of the chamfered portion 430 of the chamfered sipe 43, it is preferable that the condition Zb1 ≥ 3.0 [mm] is satisfied. It is preferable to satisfy the above relationship in order to improve drainage performance by the proximity of the sipes. If the distance Zb1 is less than 3.0 [mm], the effect of improving wet braking performance will be insufficient and it is undesirable. For the distance Zb1, it is preferable that 20.0 [mm] ≥ Zb1 is satisfied. If the distance Zb1 is greater than 20.0 [mm], the effect of the sipe unit will not be obtained and it is undesirable. For the distance Zb1, it is preferable that 20.0 [mm] ≥ Zb1 ≥ 3.0 [mm], and more preferably that 15.0 [mm] ≥ Zb1 ≥ 5.0 [mm] is satisfied.

[0056] Similarly, in Figure 4, the ratio Za2 / Zs2 of the distance Za2 from the non-chamfered sipe 52 to the sipe portion 531 of the chamfered sipe 53 in the sipe unit 50 to the maximum width Zs2 of the sipe portion 531 of the chamfered sipe 53 is preferably Za2 / Zs2 ≤ 30. If the ratio Za2 / Zs2 is greater than 30, the effect of improving wet braking performance will be insufficient, which is undesirable. More preferably, the ratio Za2 / Zs2 ≤ 20. It is preferable to satisfy the above relationship in order to improve drainage performance by the proximity of the sipes.

[0057] For the distance Zb2 from the non-chamfered sipe 52 to the end of the chamfered portion 530 of the chamfered sipe 53, it is preferable that the condition Zb2 ≥ 3.0 [mm] is satisfied. It is preferable to satisfy the above relationship in order to improve drainage performance by the proximity of the sipes. If the distance Zb2 is less than 3.0 [mm], the effect of improving wet braking performance will be insufficient and it is undesirable. For the distance Zb2, it is preferable that 20.0 [mm] ≥ Zb2 is satisfied. If the distance Zb2 is greater than 20.0 [mm], the effect of the sipe unit will not be obtained and it is undesirable. For the distance Zb2, it is preferable that 20.0 [mm] ≥ Zb2 ≥ 3.0 [mm], and more preferably that 15.0 [mm] ≥ Zb2 ≥ 5.0 [mm] is satisfied.

[0058] In this disclosure, distances Za1 and Za2 may be collectively referred to as "distance Za." In this disclosure, distances Zb1 and Zb2 may be collectively referred to as "distance Zb." In this disclosure, maximum widths Zm1 and Zm2 may be collectively referred to as "maximum width Zm." In this disclosure, maximum widths Zs1 and Zs2 may be collectively referred to as "maximum width Zs."

[0059] Referring to Figure 3, and focusing on the non-chamfered sipes 42 of the sipe unit 40, a single non-chamfered sipe 42 is positioned between a pair of adjacent chamfered sipes 43a and 43b in the circumferential direction of the tire. We define the pair of chamfered sipes 43a as the close chamfered sipe 43a, which is positioned close to the non-chamfered sipe 42, and the pair of chamfered sipes 43a and 43b as the distant chamfered sipe 43b, which is positioned farther from the non-chamfered sipe 42. For the sake of explanation, the groove width of the distant chamfered sipe 43b is depicted wider to clearly show its centerline. In reality, the groove width of the distant chamfered sipe 43b is equivalent to that of the other sipes. In the first middle section 32, the ratio Dbmax1 of the maximum value of the tire circumferential distance Db from the center line of the sipe portion 431 of the distant chamfered sipe 43b to the center line of the non-chamfered sipe 42, to the maximum value of the tire circumferential distance Da from the center line of the sipe portion 43a to the center line of the non-chamfered sipe 42, is Dbmax1 / Damax1. 1.50 ≤ Dbmax1 / Damax1 ≤ 4.00 It is preferable that the ratio Dbmax1 / Damax1 be within this range. The above range is appropriate for improving wet braking performance. If the ratio Dbmax1 / Damax1 is less than 1.50, the improvement effect on dry and wet handling stability performance will be insufficient and is undesirable. If the ratio Dbmax1 / Damax1 is greater than 4.00, the improvement effect on wet braking performance will be insufficient and is undesirable.

[0060] Referring to Figure 4, and focusing on the non-chamfered sipes 52 of the sipe unit 50, a single non-chamfered sipe 52 is positioned between a pair of adjacent chamfered sipes 53a and 53b in the circumferential direction of the tire. We define the pair of chamfered sipes 53a and 53b as the close chamfered sipe 53a, which is positioned close to the non-chamfered sipe 52, and the pair of chamfered sipes 53a and 53b as the distant chamfered sipe 53b, which is positioned farther from the non-chamfered sipe 52. For the sake of explanation, the groove width of the distant chamfered sipe 53b is depicted wider to clearly show its centerline. In reality, the groove width of the distant chamfered sipe 53b is equivalent to that of the other sipes. In the second middle section 33, the ratio Dbmax2 of the maximum value of the tire circumferential distance Db from the center line of the sipe portion 531 of the distant chamfered sipe 53b to the center line of the non-chamfered sipe 52, to the maximum value of the tire circumferential distance Da from the center line of the sipe portion 431 of the nearby chamfered sipe 53a to the center line of the non-chamfered sipe 52, is Dbmax2 / Damax2. 1.20 ≤ Dbmax2 / Damax2 ≤ 3.00 It is preferable that the ratio Dbmax2 / Damax2 be within this range. The above range is appropriate for improving wet braking performance. If the ratio Dbmax2 / Damax2 is less than 1.20, the improvement effect on dry and wet handling stability performance will be insufficient and is undesirable. If the ratio Dbmax2 / Damax2 is greater than 3.00, the improvement effect on wet braking performance will be insufficient and is undesirable.

[0061] The groove width of the non-chamfered sipes 42 and 52 is preferably 0.5 mm or more and 1.5 mm or less. The groove depth of the non-chamfered sipes 42 and 52 is preferably 2.0 mm or more and less than or equal to the maximum groove depth of the circumferential main groove 20. The above dimensional range is preferred in order to enhance the effect of improving wet braking performance and dry handling stability performance. If the maximum width of the non-chamfered sipes 42 and 52 is less than 0.5 mm or the maximum groove depth is less than 2.0 mm, the drainage performance will be insufficient and this is undesirable. If the maximum width of the non-chamfered sipes 42 and 52 is greater than 1.5 mm or the maximum groove depth is deeper than the circumferential main groove 20, the effect of improving dry handling stability performance will be insufficient and this is undesirable. More preferably, the maximum width of the non-chamfered sipes 42 and 52 is 0.5 mm or more and 1.0 mm or less, and the maximum groove depth is 3.0 mm or more and 6.0 mm or less. The same applies to the sipe portion 431 of the chamfered sipe 43 and the sipe portion 531 of the chamfered sipe 53.

[0062] Referring to Figure 2, the chamfered sipes 43 and non-chamfered sipes 42 in each of the multiple sipe units 40 of the first middle land section 32 communicate with the shoulder main groove 23. In other words, the chamfered sipes 43 and non-chamfered sipes 42 communicate with the same shoulder main groove 23, rather than being arranged in a staggered pattern that alternately communicates with different main grooves. Similarly, the chamfered sipes 53 and non-chamfered sipes 52 in each of the multiple sipe units 50 of the second middle land section 33 communicate with the shoulder main groove 24. In other words, the chamfered sipes 53 and non-chamfered sipes 52 communicate with the same shoulder main groove 24, rather than being arranged in a staggered pattern that alternately communicates with different main grooves. By arranging each sipe to communicate with one end of the same rib in this way, it becomes possible to achieve a higher level of both dry and wet handling stability.

[0063] Referring to Figure 2, the chamfered sipes 43 and non-chamfered sipes 42 in each of the multiple sipe units 40 of the first middle land section 32 communicate with the shoulder main groove 23, which is the outer main groove in the tire width direction, rather than the inner main groove in the tire width direction. That is, the chamfered sipes 43 and non-chamfered sipes 42 communicate with the shoulder main groove 23, which is the outer main groove, rather than in a staggered arrangement where they alternately communicate with the inner and outer main grooves in the tire width direction. Similarly, the chamfered sipes 53 and non-chamfered sipes 52 in each of the multiple sipe units 50 of the second middle land section 33 communicate with the shoulder main groove 24, which is the outer main groove in the tire width direction, rather than the inner main groove in the tire width direction. That is, the chamfered sipes 53 and non-chamfered sipes 52 communicate with the shoulder main groove 24, which is the outer main groove, rather than in a staggered arrangement where they alternately communicate with the inner and outer main grooves in the tire width direction. In this way, each sipe communicates with the outer main groove adjacent to the land area, making it possible to further improve dry / wet handling stability.

[0064] Referring to Figure 2, each shallow bottom section 41 of the first middle section 32 is arranged so that the V-shaped tops 410 of each shallow bottom section 41 are facing the same direction in the tire circumferential direction. Similarly, each shallow bottom section 51 of the second middle section 33 is arranged so that the V-shaped tops 510 of each shallow bottom section 51 are facing the same direction in the tire circumferential direction. The V-shaped tops 410 of each shallow bottom section 41 of the first middle section 32 and the V-shaped tops 510 of each shallow bottom section 51 of the second middle section 33 are arranged so that they are facing opposite directions in the tire circumferential direction. That is, the tops 410 face upwards in Figure 2, and the tops 510 face downwards in Figure 2. Within the first middle section 32, the tops 410 of adjacent shallow bottom sections 41 in the circumferential direction are not arranged alternately in opposite directions, but rather are arranged to face the same direction. Within the second middle land section 33, the tops 510 of adjacent shallow bottom sections 51 in the circumferential direction are not arranged alternately in opposite directions, but rather in the same direction in the circumferential direction. Furthermore, the tops 410 of the shallow bottom section 41 in the first middle land section 32 and the tops 510 of the shallow bottom section 51 in the second middle land section 33 are not in the same direction in the circumferential direction, but are arranged in opposite directions. By arranging the V-shaped shallow grooves in this way, the rigidity of the first middle land section 32 and the second middle land section 33 is ensured, and deformation of each land section can be suppressed. This contributes to improving the DRY / WET handling stability performance.

[0065] [Differentiation] Figure 7 shows a modified version of the first middle-distance track and field section. Figure 8 shows a modified version of the second middle-distance track and field section.

[0066] Referring to Figure 7, the first middle land section 32a has a closure groove 44 provided in the direction of extension of the chamfered sipe. The closure groove 44 has approximately the same width as the chamfered portion 430 of the chamfered sipe 43. The closure groove 44 is not connected to the chamfered sipe 43 and is independent.

[0067] Referring to Figure 8, the second middle land section 33a has a closure groove 54 provided in the direction of extension of the chamfered sipe. The closure groove 54 has approximately the same width as the chamfered portion 530 of the chamfered sipe 53. The closure groove 54 is not connected to the chamfered sipe 53 and is independent.

[0068] By providing occluding grooves 44 and 54 at the sipe ends where stress is concentrated during rolling, stress concentration can be mitigated and crack propagation can be suppressed. In other words, even if cracks occur, they can be terminated at the occluding grooves 44 and 54, thereby suppressing crack propagation. Furthermore, by using independent, short, and shallow occluding grooves, a decrease in tread rigidity can be prevented, thus preventing a decrease in dry performance.

[0069] Furthermore, it is possible to provide only one of the blocking grooves, instead of both the blocking groove 44 in the first middle land section 32a and the blocking groove 54 in the second middle land section 33a. In the middle land sections provided with blocking grooves 44 and 54, as described above, stress concentration can be alleviated and crack propagation can be suppressed.

[0070] [Examples] Figures 9A to 9K are charts showing the results of performance tests of the tires according to this embodiment. In these performance tests, wet braking performance, wet handling stability performance, dry handling stability performance, and crack propagation resistance were evaluated for multiple types of test tires. A test tire with tire size 215 / 55R17 98W 17×7J was mounted on a JATMA-specified rim, and the JATMA-specified internal pressure and load were applied to this test tire. The test tire was also mounted on all wheels of a passenger car, which was the test vehicle.

[0071] (1) The evaluation of wet braking performance involves the test vehicle driving on an asphalt road sprayed with 1 mm of water, and measuring the braking distance from an initial speed of 80 km / h. Based on the measurement results, an index evaluation is performed with Comparative Example 1 as the baseline (100). In terms of evaluation, a higher numerical value is preferable.

[0072] (2) The evaluation of wet handling stability performance involves the test vehicle driving on a wet test course, and a professional test driver performing a subjective evaluation of lane change performance, cornering performance, etc. This evaluation is performed using an index evaluation with Comparative Example 1 as the baseline (100). A higher numerical value is preferable.

[0073] (3) The evaluation of dry handling stability performance involves the test vehicle driving on a dry test course, and a professional test driver performing a subjective evaluation of lane change performance, cornering performance, etc. This evaluation is performed using an index evaluation with Comparative Example 1 as the baseline (100). A higher numerical value is preferable.

[0074] (4) The evaluation of crack propagation resistance was conducted by investigating cracks during a 30,000 km road test. The conventional example was used as the baseline (100), and the crack occurrence rate and crack growth rate were expressed as an index. A higher value is preferable.

[0075] The test tires of each embodiment have the configuration shown in Figures 1 and 2. The conventional tire is a tire without sipe units. The tire of Comparative Example 1 has sipe units, and the rib width W1 of the first middle section and the rib width W2 of the second middle section are equal. The tires of Comparative Examples 2 and 3 have sipe units, and the rib width W2 of the second middle section is larger than the rib width W1 of the first middle section.

[0076] As the test results show, the test tires for each embodiment showed good results in terms of wet braking performance, wet handling stability performance, dry handling stability performance, and crack propagation resistance.

[0077] This disclosure encompasses the following inventions: [1] It comprises one or more center main grooves, a pair of shoulder main grooves provided on the outer side of the center main groove in the tire width direction, and a pair of shoulder land sections and first and second middle land sections separated by these main grooves. The first and second middle land portions each have a plurality of chamfered sipe portions having a chamfered portion and a sipe portion, and non-chamfered sipe portions having no chamfered portion, the chamfered sipe portions and the non-chamfered sipe portions are alternately arranged in the tire circumferential direction, the first and second middle land portions each have a plurality of sipe units each composed of the non-chamfered sipe portions and the chamfered sipe portions, of the chamfered sipe portions located on both sides in the tire circumferential direction of the non-chamfered sipe portion, the chamfered sipe portion closer to the non-chamfered sipe portion is defined as the adjacent chamfered sipe portion, and the combination of the non-chamfered sipe portion and the adjacent chamfered sipe portion is the sipe unit, a rib width W1 of the first middle land portion and a rib width W2 of the second middle land portion have a relationship of W1 < W2, a tire in which a distance D1 between the non-chamfered sipe portion and the chamfered sipe portion of the sipe unit in the first middle land portion has a relationship of D1 < D2 with respect to a distance D2 between the non-chamfered sipe portion and the chamfered sipe portion of the sipe unit in the second middle land portion. [2] The tire according to [1], in which a distance Zb from the non-chamfered sipe portion to an end portion of the chamfered portion of the chamfered sipe portion is 20.0 [mm] or less. [3] The tire according to [1] or [2], in which a ratio W2 / W1 of the rib width W2 to the rib width W1 is 1.1 or more and 1.6 or less. [4] The tire according to any one of [1] to [3], in which a ratio D2 / D1 of the distance D2 to the distance D1 is 1.2 or more and 2.0 or less. [5] The tire according to any one of [1] to [4], in which a ratio D1 / W1 of the distance D1 to the rib width W1 is 0.2 or more and 0.8 or less, and a ratio D2 / W2 of the distance D2 to the rib width W2 is 0.2 or more and 0.8 or less. [6] A tire according to any one of [1] to [5], wherein the inclination angle θ1 of the chamfered sipe of the sipe unit in the first middle land portion with respect to the tire circumferential direction and the inclination angle θ2 of the chamfered sipe of the sipe unit in the second middle land portion with respect to the tire circumferential direction are in a relationship of θ1 > θ2. [7] The tire according to [6], wherein the inclination angles θ1 and θ2 are 30 degrees or more and 80 degrees or less. [8] The tire according to [6], wherein the difference between the inclination angle θ1 and the inclination angle θ2, θ1-θ2, is 5 [deg] or more and 35 [deg] or less. [9] The inclination angle θ1' of the non-chamfered sipe of the sipe unit in the first middle land section with respect to the tire circumferential direction and the inclination angle θ1 are -10[deg]≦θ1-θ1'≦10[deg] They have a relationship, The inclination angle θ2' of the non-chamfered sipe of the sipe unit in the second middle land section with respect to the tire circumferential direction and the inclination angle θ2 are -10[deg]≦θ2-θ2'≦10[deg] The tire described in [6] has the relationship.

[10] The ratio X1 / W1 of the tire width direction extension distance X1 of the chamfered sipe portion of the first middle land section to the rib width W1 is, 0.40 ≤ X1 / W1 ≤ 0.90 They have a relationship, The ratio X2 / W2 of the tire width direction extension distance X2 of the chamfered sipe portion of the second middle land section to W2 is, 0.40 ≤ X² / W² ≤ 0.90 A tire described in any one of [1] to [9] having the relationship [1].

[11] The first middle section is a tire located on the inside of the vehicle, as described in any one of [1] to

[10] .

[12] The aforementioned chamfered sipe includes a sipe portion and a chamfered portion. The tire according to any one of [1] to

[11] , wherein the chamfered portion is provided only on the edge on the non-chamfered sipe side of the edges on both sides of the sipe portion.

[13] The ratio Zm / Zs of the maximum width of the chamfered sipe to the maximum width Zs of the sipe portion of the chamfered sipe is 2.00 ≤ Zm / Zs ≤ 6.00 The conditions are met, and the maximum width Zs is, 0.5 [mm] ≤ Zs ≤ 1.5 [mm] A tire listed in any one of [1] through

[12] that meets the following conditions.

[14] With respect to the maximum width Zs of the sipe portion of the chamfered sipe, The ratio Za / Zs of the distance Za from the non-chamfered sipe to the sipe portion of the chamfered sipe in the sipe unit is, Za / Zs≦30 And, The distance Zb from the non-chamfered sipe to the end of the chamfered portion of the chamfered sipe is, Zb ≥ 3.0 [mm] A tire listed in any one of the following [1] to

[13] that meets the following conditions.

[15] A single non-chamfered sipe is positioned between a pair of adjacent chamfered sipes in the circumferential direction of the tire. A close chamfered sipe is defined as the pair of chamfered sipes that are positioned close to the non-chamfered sipe, and a distant chamfered sipe is defined as the pair of chamfered sipes that are positioned far from the non-chamfered sipe. In the first middle-distance track and field event, The ratio Dbmax1 of the maximum value Dbmax1 of the tire circumferential distance Db from the center line of the sipe portion of the distant chamfered sipe to the center line of the non-chamfered sipe to the maximum value Damax1 of the tire circumferential distance Da from the center line of the sipe portion of the nearby chamfered sipe to the center line of the non-chamfered sipe is Dbmax1 / Damax1. 1.50 ≤ Dbmax1 / Damax1 ≤ 4.00 It is within the range, In the second middle-distance track and field event, The ratio Dbmax2 of the maximum value of the tire circumferential distance Db from the center line of the sipe portion of the distant chamfered sipe to the center line of the non-chamfered sipe, to the maximum value of the tire circumferential distance Da from the center line of the sipe portion of the nearby chamfered sipe to the center line of the non-chamfered sipe, is Dbmax2 / Damax2. 1.20 ≤ Dbmax2 / Damax2 ≤ 3.00 A tire listed in any one of the following [1] through

[14] within the range.

[16] The groove width of the non-chamfered sipe is 0.5 mm or more and 1.5 mm or less. The tire according to any one of [1] to

[15] , wherein the groove depth of the non-chamfered sipe is 2.0 [mm] or more and is less than or equal to the maximum groove depth of the main groove.

[17] The chamfered sipes and the non-chamfered sipes in each of the multiple sipe units of the first middle land section communicate with the same main groove. The chamfered sipes and the non-chamfered sipes in each of the multiple sipe units of the second middle land section communicate with the same main groove, as described in any one of [1] to

[16] .

[18] The chamfered sipes and non-chamfered sipes in each of the multiple sipe units of the first middle section communicate with the outer main groove in the tire width direction. The chamfered sipes and non-chamfered sipes in each of the plurality of sipe units in the second middle land section communicate with the outer main groove in the tire width direction, according to any one of [1] to

[17] .

[19] The first middle land section and the second middle land section each further include a shallow bottom section having a V-shape with its top facing in the circumferential direction of the tire, The shallow bottom portion of the first middle land portion is connected to the non-chamfered sipe of the first middle land portion, The shallow bottom portion of the second middle land portion is connected to the non-chamfered sipe of the second middle land portion, The top of the V-shaped shallow bottom of the first middle land section is oriented in the same direction in the tire circumferential direction. The V-shaped tops of the shallow bottom portion of the second middle land section are oriented in the same direction in the tire circumferential direction. The tire according to any one of [1] to

[18] , wherein the top of the V-shaped portion of the shallow bottom of the first middle land portion and the top of the V-shaped portion of the shallow bottom of the second middle land portion are oriented in opposite directions in the circumferential direction of the tire.

[20] In at least one of the first middle track and the second middle track, The chamfered sipe has a closing groove provided in the direction of extension, The tire according to any one of [1] to

[19] , wherein the closed groove is not connected to the chamfered sipe. [Explanation of Symbols]

[0078] 1. Pneumatic tire 2 Tread section 3. Shoulder section 4. Sidewall section 5. Bead section 6. Carcass layer 7 Belt layer 7a, 7b belt 8 Belt reinforcement layer 10 Ground plane 15 Bead core 16 Bead Filler 20 Circumferential main groove 21, 22 Outer center main groove 23 Inner shoulder main groove 24 Outer shoulder main groove 31 Center Track and Field Club 32, 32a 1st Middle Track and Field Club 33, 33a Second Middle Track and Field Club 34, 35 Shoulder Track and Field Club 40, 50 sipe units 41, 51 Shallow bottom part 42, 52 non-chamfered sipes 43, 43a, 43b, 53, 53a, 53b Chamfered sipes 44, 54 Obstruction groove 61, 64 lug grooves 62, 65, 71 sipes 63 Circumferential narrow groove 430, 530 Chamfered part 431, 531 Sipes

Claims

1. It comprises one or more center main grooves, a pair of shoulder main grooves provided on the outer side of the center main groove in the tire width direction, and a pair of shoulder land sections and first and second middle land sections separated by these main grooves. The first and second middle land sections have a plurality of chamfered sipes having a sipe portion and a chamfered portion, and a plurality of non-chamfered sipes that do not have a chamfered portion. The chamfered sipes and the non-chamfered sipes are arranged alternately in the circumferential direction of the tire. The first and second middle land sections have a plurality of sipe units composed of the non-chamfered sipes and the chamfered sipes, Of the chamfered sipes located on both sides of the non-chamfered sipe in the tire circumferential direction, the chamfered sipe on the side closer to the non-chamfered sipe is designated as the adjacent chamfered sipe, and the combination of the non-chamfered sipe and the adjacent chamfered sipe constitutes the sipe unit. The rib width W1 of the first middle section and the rib width W2 of the second middle section have the relationship W1 < W2. A tire in which the distance D1 between the non-chamfered sipe and the chamfered sipe of the sipe unit in the first middle land portion is such that D1 < D2 with respect to the distance D2 between the non-chamfered sipe and the chamfered sipe of the sipe unit in the second middle land portion.

2. The tire according to claim 1, wherein the distance Zb from the non-chamfered sipe to the end of the chamfered portion of the chamfered sipe is 20.0 [mm] or less.

3. The tire according to claim 1 or 2, wherein the ratio W2 / W1 of the rib width to the rib width W1 is 1.1 or more and 1.6 or less.

4. The tire according to claim 1 or 2, wherein the ratio of the interval D2 to the interval D1, D2 / D1, is 1.2 or more and 2.0 or less.

5. The tire according to claim 1 or 2, wherein the ratio D1 / W1 of the spacing D1 to the rib width W1 is 0.2 or more and 0.8 or less, and the ratio D2 / W2 of the spacing D2 to the rib width W2 is 0.2 or more and 0.8 or less.

6. The tire according to claim 1 or 2, wherein the inclination angle θ1 of the chamfered sipe of the sipe unit in the first middle land portion with respect to the tire circumferential direction and the inclination angle θ2 of the chamfered sipe of the sipe unit in the second middle land portion with respect to the tire circumferential direction are in the relationship θ1 > θ2.

7. The tire according to claim 6, wherein the inclination angles θ1 and θ2 are 30 degrees or more and 80 degrees or less.

8. The tire according to claim 6, wherein the difference between the inclination angle θ1 and the inclination angle θ2, θ1 - θ2, is 5 [deg] or more and 35 [deg] or less.

9. The inclination angle θ1' of the non-chamfered sipe of the sipe unit in the first middle land section with respect to the tire circumferential direction and the inclination angle θ1 are -10[deg]≦θ1-θ1'≦10[deg] They have a relationship, The inclination angle θ2' of the non-chamfered sipe of the sipe unit in the second middle land section with respect to the tire circumferential direction and the inclination angle θ2 are -10[deg]≦θ2-θ2'≦10[deg] The tire according to claim 6 having the relationship.

10. The ratio X1 / W1 of the tire width direction extension distance X1 of the chamfered sipe portion in the first middle land section to the rib width W1 is, 0.40 ≤ X1 / W1 ≤ 0.90 They have a relationship, The ratio X2 / W2 of the tire width direction extension distance X2 of the chamfered sipe in the second middle land section to W2 is, 0.40 ≤ X² / W² ≤ 0.90 A tire according to claim 1 or 2 having the relationship described above.

11. The tire according to claim 1 or 2, wherein the first middle land portion is located on the inside of the vehicle mounting.

12. The aforementioned chamfered sipe includes a sipe portion and a chamfered portion. The tire according to claim 1 or 2, wherein the chamfered portion is provided only on the edge on the non-chamfered sipe side of the edges on both sides of the sipe portion.

13. The ratio Zm / Zs of the maximum width Zm of the chamfered sipe to the maximum width Zs of the sipe portion of the chamfered sipe is 2.00 ≤ Zm / Zs ≤ 6.00 The conditions are met, and the maximum width Zs is, 0.5 [mm]≦Zs≦1.5 [mm] A tire according to claim 1 or 2 that satisfies the conditions.

14. With respect to the maximum width Zs of the sipe portion of the chamfered sipe, The ratio Za / Zs of the distance Za from the non-chamfered sipe to the sipe portion of the chamfered sipe in the sipe unit is, Za / Zs ≤ 30 And, The distance Zb from the non-chamfered sipe to the end of the chamfered portion of the chamfered sipe is, Zb≧3.0 [mm] A tire according to claim 1 or 2 that satisfies the conditions.

15. A single non-chamfered sipe is positioned between a pair of adjacent chamfered sipes in the circumferential direction of the tire. A close chamfered sipe is defined as the pair of chamfered sipes that are positioned close to the non-chamfered sipe, and a distant chamfered sipe is defined as the pair of chamfered sipes that are positioned far from the non-chamfered sipe. In the first middle-distance track and field event, The ratio Dbmax1 of the maximum value Db of the tire circumferential distance Db from the center line of the sipe portion of the remote chamfered sipe to the center line of the non-chamfered sipe, to Dbmax1 of the maximum value Damax1 of the tire circumferential distance Da from the center line of the sipe portion of the nearby chamfered sipe to the center line of the non-chamfered sipe, is Dbmax1 / Damax1. 1.50 ≤ Dbmax1 / Dbmax1 ≤ 4.00 It is within the range, In the second middle-distance track and field club, The ratio Dbmax2 of the maximum value of the tire circumferential distance Db from the center line of the sipe portion of the remote chamfered sipe to the center line of the non-chamfered sipe, to the maximum value of the tire circumferential distance Da from the center line of the sipe portion of the nearby chamfered sipe to the center line of the non-chamfered sipe, is Dbmax2 / Damax2. 1.20 ≤ Dbmax² / Damax² ≤ 3.00 A tire according to claim 1 or 2, which is within the range of the tire.

16. The groove width of the non-chamfered sipe is 0.5 mm or more and 1.5 mm or less. The tire according to claim 1 or 2, wherein the groove depth of the non-chamfered sipe is 2.0 mm or more and less than or equal to the maximum groove depth of the main groove.

17. The chamfered sipes and the non-chamfered sipes in each of the multiple sipe units of the first middle land section communicate with the same main groove. The tire according to claim 1 or 2, wherein the chamfered sipes and the non-chamfered sipes in each of the plurality of sipe units in the second middle land section communicate with the same main groove.

18. The chamfered sipes and non-chamfered sipes in each of the multiple sipe units of the first middle section communicate with the outer main groove in the tire width direction. The tire according to claim 1 or 2, wherein the chamfered sipes and the non-chamfered sipes in each of the plurality of sipe units in the second middle land section communicate with the outer main groove in the tire width direction.

19. The first middle land section and the second middle land section each further include a shallow bottom section having a V-shape with its top facing in the circumferential direction of the tire, The shallow bottom portion of the first middle land portion is connected to the non-chamfered sipe of the first middle land portion, The shallow bottom portion of the second middle land portion is connected to the non-chamfered sipe of the second middle land portion, The V-shaped tops of the shallow bottom portion of the first middle land section are oriented in the same direction in the tire circumferential direction. The V-shaped tops of the shallow bottom portion of the second middle land section are oriented in the same direction in the tire circumferential direction. The tire according to claim 1 or 2, wherein the V-shaped top of the shallow bottom of the first middle land portion and the V-shaped top of the shallow bottom of the second middle land portion are oriented in opposite directions in the tire circumferential direction.

20. In at least one of the first middle track and field area and the second middle track and field area, The chamfered sipe has a closing groove provided in the direction of extension, The tire according to claim 1 or 2, wherein the blocking groove is not connected to the chamfered sipe.

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