Tire

Abstract

The present disclosure improves wet braking performance and steering stability. This tire for which a vehicle mounting direction is designated has: a center main groove; a pair of shoulder main grooves provided on outer sides of the center main groove in the tire width direction; a first middle land portion sandwiched between one of the shoulder main grooves and the center main groove; and a second middle land portion sandwiched between the other of the shoulder main grooves and the center main groove. At least one of the middle land portions includes sipe units each including a pair of a chamfered sipe having a chamfered portion on at least one side in an extending direction and a non-chamfered sipe not having the chamfered portion. One end of the chamfered sipe including a sipe portion and the chamfered portion opens to one of the center main groove and the shoulder main groove, and the other end terminates without opening. The sipe units are arranged in the tire circumferential direction. One end of the chamfered sipe of one of the adjacent sipe units opens to the center main groove, and one end of the chamfered sipe of the other of the adjacent sipe units opens to the shoulder main groove. The rib width of the middle land portion on the inner side when mounted to a vehicle is narrower than the rib width of the middle land portion on the outer side when mounted to the vehicle.

Description

Tire

[0001] The present disclosure relates to a tire.

[0002] A method is known in which a sip unit combining a chamfered sip and a non-chamfered sip is arranged to effectively improve wet (hereinafter, WET) braking performance (for example, Patent Document 1, Patent Document 2).

[0003] Japanese Patent No. 7167840 Japanese Patent No. 7633484

[0004] However, due to the collapse of the sip due to insufficient rigidity of the tread surface, the WET braking performance and the handling stability performance may be insufficient. The present disclosure has been made in view of the above, and its object is to improve the WET braking performance and the handling stability performance by appropriately arranging the sip unit and the relationship between the middle rib widths.

[0005] To solve the above-mentioned problems and achieve the objective, a tire according to one aspect of the present disclosure is a tire with a specified mounting direction to a vehicle, comprising one or more center main grooves, a pair of shoulder main grooves provided on the outside of the center main groove in the tire width direction, a pair of shoulder land portions and first and second middle land portions partitioned by these main grooves, at least one of the first and second middle land portions having a plurality of chamfered sipes having a sipe portion and a chamfered portion, and non-chamfered sipes not having a chamfered portion, the chamfered sipes and non-chamfered sipes are arranged alternately in the tire circumferential direction, at least one of the first and second middle land portions has 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 sipe unit is a combination of the chamfered sipe on the side closer to the non-chamfered sipe and the non-chamfered sipe, one end of the chamfered sipe opens into either the center main groove or the shoulder main groove, and the other end of the chamfered sipe terminates without opening into the center main groove or the shoulder main groove, a plurality of the sipe units are arranged in the circumferential direction of the tire, one end of the chamfered sipe of one adjacent sipe unit in the circumferential direction of the tire opens into the center main groove, and one end of the chamfered sipe of the other opens into the shoulder main groove, and the rib width Wi of the middle land portion on the inner side of the first and second middle land portions mounted on the vehicle is narrower than the rib width Wo of the middle land portion on the outer side of the vehicle, and the rib width Wi of the middle land portion on the outer side of the vehicle is narrower than the rib width Wo of the middle land portion on the outer side of the vehicle.

[0006] According to this disclosure, wet braking performance and handling stability can be improved.

[0007] Figure 1 is a meridional cross-sectional view of a pneumatic tire according to this embodiment. Figure 2 is a plan view of the tread portion of the pneumatic tire according to this embodiment. Figure 3 is an enlarged view of a part of the center land portion 31 in Figure 2. Figure 4 is a schematic diagram showing an example of a cross-section of section A-A in Figure 3. Figure 5 is a schematic diagram showing a cross-section of section A-A in Figure 3 in a ground contact state. Figure 6 is an enlarged view of a part of Figure 2. Figure 7 is a diagram showing the tread portion of a meridional cross-section of a pneumatic tire according to a modified example. Figure 8 is a schematic diagram showing an example of a cross-section of a chamfered sipe. Figure 9 is a schematic diagram showing an example of a cross-section of a chamfered sipe. Figure 10 is a schematic diagram showing an example of a cross-section of a chamfered sipe. Figure 11A is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11B is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11C is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11D is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11E is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11F is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11G is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11H is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11I is a chart showing the results of a performance test of the tire according to the embodiment. Figure 11J is a chart showing the results of a performance test of the tire according to the embodiment.

[0008] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following descriptions of each embodiment, the same or equivalent components as those in other embodiments will be denoted by the same reference numerals, and their descriptions will be simplified or omitted. The present invention is not limited by each embodiment. Furthermore, the components of each embodiment include those that are easily substituted or substantially identical to those that a person skilled in the art can substitute. In addition, the configurations described below can be combined as appropriate. Furthermore, configurations can be omitted, substituted, or modified without departing from the spirit of the invention.

[0009] [Pneumatic Tire] In the following description, pneumatic tire 1 will be used as an example of a tire relating to the present disclosure. Pneumatic tire 1, which is an example of a tire relating to the present disclosure, can be filled with air, an inert gas such as nitrogen, or other gases.

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

[0011] In the following explanation, the tire radial direction refers to the direction perpendicular to the rotation axis (not shown) of the pneumatic tire 1. The inner side of the tire radial direction refers to the side toward the rotation axis in the tire radial direction, and the outer side of the tire radial direction refers to the side away from the rotation axis in the tire radial direction. The tire circumferential direction refers to the direction around the rotation axis. The tire width direction refers to the direction parallel to the rotation axis. The inner side of the tire width direction refers to the side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the outer side of 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 perpendicular to the rotation axis of the pneumatic tire 1 and passing through the center of the tire width of the pneumatic tire 1. The position of the tire equatorial plane CL in the tire width direction coincides with the tire width direction center line, which is the center position of the pneumatic tire 1 in the tire width direction. The tire equatorial line is a line that lies on the tire equatorial plane CL and runs along the circumferential direction of the pneumatic tire 1. In this embodiment, it is denoted by the same symbol "CL" as the tire equatorial plane.

[0012] As shown in Figure 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. The pneumatic tire 1 also includes a carcass layer 6, a belt layer 7, and a belt reinforcement layer 8.

[0013] The tread portion 2 is made of rubber material (tread rubber) and is exposed at the outermost edge in the radial direction of the pneumatic tire 1, with its outer surface forming the outline of the pneumatic tire 1. The outer surface of the tread portion 2 is mainly the surface that can come into contact with the road surface when driving, and is configured as the contact surface 10.

[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, 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, in the radial direction 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 (for example, 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 is the vehicle mounting outer side, and the side facing inwards from the vehicle is the vehicle mounting inner side. Note that the designation of vehicle mounting outer and vehicle mounting inner sides 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 vehicle mounting outer side and vehicle mounting inner side is specified in the tire width direction.

[0020] [Tread section] Four circumferential main grooves 20 are formed in the tire width direction on the contact surface 10 of the tread section 2, extending in the circumferential direction of the tire and continuing 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 rib width described below are measured as the maximum value of the dimension 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 edge, the groove width is measured including the notches or chamfers, with the groove opening end being the outer edge of the notches or chamfers. The groove depth and sipe depth are measured as the maximum value of the dimension 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 refers to the "standard rim" specified by JATMA, the "Design Rim" specified by TRA, or the "Measuring Rim" specified by ETRTO. Furthermore, the specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO. Finally, the specified load refers to the "maximum load capacity" specified by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified 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 vehicle-mounted inner side, 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 vehicle-mounted outer side, 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 demarcated by the inner center main groove 21 and the outer center main groove 22. In other words, the center land area 31 is formed sandwiched between the inner center main groove 21 and the outer center main groove 22. Thus, 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 and 35. The center land portion 31 is provided at a position that crosses the tire equatorial plane CL. The shoulder land portion 34 is provided with circumferential narrow grooves 63, which will be described later.

[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 Land Section] Figure 3 is an enlarged view of a portion of the center land section 31 in Figure 2. Referring to Figures 2 and 3, the center land section 31 has a plurality of non-chamfered sipes 42 and chamfered sipes 43. The non-chamfered sipes 42 and chamfered sipes 43 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.

[0027] The center section 31 has shallow grooves 41. The shallow grooves 41 are V-shaped shallow grooves with their tops 410 facing in the circumferential direction of the tire. The shallow grooves 41 are connected to the non-chamfered sipes 42. It is preferable that the V-shaped shallow grooves 41 adjacent to each other in the circumferential direction of the tire are arranged with the orientation of the V-shapes in opposite directions. By arranging the V-shaped shallow grooves in this way, block rigidity can be effectively ensured, and handling stability can be improved.

[0028] The non-chamfered sipes 42 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.

[0029] Here, we define a sipe unit 40 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 a sipe unit 40. The center land portion 31 has multiple sipe units 40. Multiple sipe units 40 are provided in the center land portion 31 in the tire circumferential direction.

[0030] It is preferable that the distance Zb from the non-chamfered sipe 42 to the end of the chamfered portion 430 of the chamfered sipe 43 is Zb ≤ 20.0 [mm]. Setting Zb ≤ 20.0 [mm] allows the sipe unit to exert its effect and improves wet braking performance. It is more preferable that the distance Zb is 5.0 [mm] ≤ Zb ≤ 15.0 [mm]. Note that the end of the chamfered portion 430 refers to the portion that corresponds to the boundary between the chamfered portion 430 and the tread surface.

[0031] It is preferable that the inclination angle θ of the chamfered sipe 43 of the sipe unit 40 with respect to the tire circumferential direction is 30 [deg] ≤ θ ≤ 80 [deg]. By setting the inclination angle of the chamfered sipe 43 within the above range, the effect of improving wet braking performance can be enhanced. It is more preferable that the inclination angle θ is 40 [deg] ≤ θ ≤ 75 [deg].

[0032] It is preferable that the inclination angle θ' of the non-chamfered sipe 42 of the sipe unit 40 with respect to the tire circumferential direction and the inclination angle θ of the chamfered sipe 43 have the relationship -10 [deg] ≤ θ - θ' ≤ 10 [deg]. In other words, it is preferable that there is almost no difference in the inclination angles and that the two are approximately parallel.

[0033] By making the chamfered sipe 43 and the non-chamfered sipe 42 of the sipe unit 40 approximately parallel, the effect of improving wet braking performance can be enhanced. It is more preferable that the difference in inclination angle is -5 [deg] ≤ θ - θ' ≤ 5 [deg].

[0034] It is preferable that the ratio X / W of the tire width extension distance X of the sipe portion 431 of the chamfered sipe 43 to the rib width W of the land portion on which the chamfered sipe 43 is provided has the relationship 0.40 ≤ X / W ≤ 0.90. By setting the tire width extension distance of the sipe portion 431 within the above range, both wet braking performance and handling stability can be achieved. It is more preferable that the ratio X / W is 0.45 ≤ X / W ≤ 0.55.

[0035] It is preferable that 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. By providing the chamfered portion 430 on only one side, i.e., on the non-chamfered sipe 42 side, the drainage effect of the sipe unit can be effectively achieved.

[0036] Preferably, the ratio Zm / Zs of the maximum width Zm of the chamfered sipe 43 to the maximum width Zs of the sipe portion 431 satisfies the condition 2.00 ≤ Zm / Zs ≤ 6.00, and the maximum width Zs satisfies the condition 0.5 [mm] ≤ Zs ≤ 1.5 [mm]. Note that the maximum width Zm of the chamfered sipe 43 is the maximum length of the chamfered sipe 43 in the direction perpendicular to the extension direction, and includes the width of the chamfered portion 430 and the groove width of the sipe portion 431.

[0037] The above relationship is preferable for achieving both drainage performance and handling stability with the chamfered sipes 43. Furthermore, it is more preferable that the ratio Zm / Zs satisfies the condition 2.00 ≤ Zm / Zs ≤ 4.00, and that the maximum width Zs is 0.5 [mm] ≤ Zs ≤ 1.0 [mm].

[0038] It is preferable that the ratio Za / Zs of the distance Za 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 Zs of the sipe portion 431 of the chamfered sipe 43 is Za / Zs ≤ 30. It is also preferable that the distance Zb from the non-chamfered sipe 42 to the end of the chamfered portion 430 of the chamfered sipe 43 satisfies the condition Zb ≥ 3.0 [mm].

[0039] This numerical range improves wet braking performance. It is more preferable that Za / Zs ≤ 20. This numerical range improves wet braking performance. It is also preferable that 20.0 [mm] ≥ Zb. This numerical range provides the effect of a sipe unit and improves wet braking performance. The distance Zb is preferably 20.0 [mm] ≥ Zb ≥ 3.0 [mm], and more preferably 15.0 [mm] ≥ Zb ≥ 5.0 [mm].

[0040] The groove width of the non-chamfered sipe 42 is preferably 0.5 mm or more and 1.5 mm or less, and the groove depth of the non-chamfered sipe 42 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 steering stability performance.

[0041] The maximum width of the non-chamfered sipe 42 is preferably 0.5 mm or more and 1.0 mm or less, and the maximum groove depth is preferably 3.0 mm or more and 6.0 mm or less. The same applies to the sipe portion 431 of the chamfered sipe 43.

[0042] As described above, in the sipe unit 40, the drainage performance can be improved by providing a chamfered portion 430 on the sipe portion 431. The non-chamfered sipe 42 adjacent to the chamfered sipe 43 bears the burden of tread deformation and suppresses chamfer crushing, thereby improving drainage performance. Furthermore, by providing the chamfered portion 430 on only one side of the edge along the sipe portion 431, rather than both sides, a balance between drainage and contact can be maintained, improving wet performance. In addition, since the sipe portion 431 terminates within the land area, tread deformation under contact is supported by the non-sipe portion, and crushing of the chamfer of the chamfered portion 430 can be suppressed.

[0043] Multiple sipe units 40 are arranged in a line in the circumferential direction of the tire on the ground. One end of a chamfered sipe 43 of adjacent sipe units 40 in the circumferential direction of the tire opens into the main groove (inner center main groove 21) on one side of the tire width direction on the ground. The other end of a chamfered sipe 43 opens into the main groove (inner shoulder main groove 23) on the other side of the tire width direction on the ground. In other words, the openings of the non-penetrating chamfered sipes 43 alternate between one side and the other side of the tire width direction on the ground, i.e., in a staggered pattern. By arranging the sipe units 40 in a staggered pattern, the balance of contact with the ground can be maintained, contributing to improved handling stability.

[0044] Incidentally, a blocking groove 44 is provided in the extending direction of the chamfered groove 43. The blocking groove 44 is not connected to the chamfered groove 43. By providing the blocking groove 44 at the end of the groove where stress concentrates during rolling, the concentration of stress can be alleviated and the progress of cracks can be suppressed. That is, even if a crack occurs, the crack can be terminated by the blocking groove 44, and the progress of the crack can be suppressed. Further, by making the blocking groove 44 an independent short blocking groove not connected to other grooves and making the blocking groove 44 shallower, a decrease in tread rigidity can be prevented and a decrease in handling stability can be prevented.

[0045] [Middle land portion] Returning to FIG. 2, similar to the center land portion 31, the first middle land portion 32 has a plurality of groove units 40. Also in the first middle land portion 32, a plurality of groove units 40 are provided in the tire circumferential direction. Similar to the center land portion 31, the second middle land portion 33 has a plurality of groove units 40. Also in the second middle land portion 33, a plurality of groove units 40 are provided in the tire circumferential direction.

[0046] Both the first middle land portion 32 and the second middle land portion 33 have groove units 40. That is, the first middle land portion 32 and the second middle land portion 33 each have a groove unit 40. By providing the groove units 40 on both the first middle land portion 32 and the second middle land portion 33, the effect of improving the WET braking performance can be obtained more effectively. As described above, since the groove unit 40 is also provided in the center land portion 31, the effect of improving the WET braking performance can be obtained more effectively.

[0047] The sipe units 40 of the first middle land portion 32 and the second middle land portion 33 include a non-chamfered sipe 42 and a chamfered sipe 43, similar to the sipe unit 40 of the center land portion 31. The distance Zb from the non-chamfered sipe 42 to the end of the chamfered portion 430 of the chamfered sipe 43, the inclination angle θ of the chamfered sipe 43 of the sipe unit 40 with respect to the tire circumferential direction, the difference between the inclination angle θ' of the non-chamfered sipe 42 of the sipe unit 40 with respect to the tire circumferential direction and the inclination angle θ, the ratio X / W of the tire width direction extension distance X of the sipe portion 431 to the rib width W of the land portion where the chamfered sipe 43 is provided, the ratio Zm / Zs of the maximum width Zm of the chamfered sipe 43 to the maximum width Zs of the sipe portion 431, the ratio Za / Zs of the distance Za 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 Zs of the sipe portion 431, the groove width of the non-chamfered sipe 42, and the groove depth of the non-chamfered sipe 42 are the same as those of each part of the center land portion 31 described with reference to FIG. 3. The closed groove 44 and its effect are also the same as those of each part of the center land portion 31.

[0048] Focusing on the center land portion 31, the first middle land portion 32, and the second middle land portion 33, sipe units 40 are provided on these land portions. Also, on these land portions, together with the sipe units 40, there are provided a V-shaped shallow groove portion having a V shape with its top facing the tire circumferential direction and a closed groove 44 provided in the extending direction of the chamfered sipe 43. Also, only the sipe unit 40 may be provided. That is, on these land portions, only the sipe unit 40 may be provided, or only the sipe unit 40 and the shallow groove portion 41 or the closed groove 44 may be provided. By the absence of single lug grooves or single sipers other than the above on these land portions, it becomes possible to more effectively achieve both wet braking and handling stability.

[0049] Here, of the first middle land section 32 and the second middle land section 33, the rib width Wi of the first middle land section 32, which is mounted on the vehicle, is narrower than the rib width Wo of the second middle land section 33, which is mounted on the vehicle. That is, the relationship is rib width Wi < rib width Wo. By increasing the area of ​​the land section on the outside of the vehicle, steering stability is improved, while by decreasing the area of ​​the land section on the inside of the vehicle, the groove area is increased, thereby achieving a balance between wet braking performance and dry steering stability performance.

[0050] The ratio of rib width Wo to rib width Wi, Wo / Wi, is preferably 1.1 ≤ Wo / Wi ≤ 1.6. This range is appropriate for maintaining the overall rigidity balance of the tread pattern 2. More preferably, the ratio Wo / Wi is 1.2 ≤ Wo / Wi ≤ 1.4.

[0051] Furthermore, focusing on the two center main grooves, the inner center main groove 21 and the outer center main groove 22, the groove width Li of the inner center main groove 21 is wider than the groove width Lo of the outer center main groove 22. In addition to the relationship between the rib width Wi of the first middle land section 32 and the rib width Wo of the second middle land section 33, which is Wi < Wo, by setting the groove width relationship to Li > Lo, it is possible to more effectively achieve both handling stability and wet braking performance.

[0052] In this case, the ratio of groove width Li to groove width Lo, Li / Lo, is preferably 1.03 ≤ Li / Lo ≤ 1.30. This range is appropriate for maintaining the overall rigidity balance of the tread pattern 2. Furthermore, the ratio Li / Lo is more preferably 1.05 ≤ Li / Lo ≤ 1.20.

[0053] Preferably, the groove width Xi of the inner shoulder main groove mounted on the vehicle is wider than the groove width Li, and the groove width Xo of the outer shoulder main groove mounted on the vehicle is wider than the groove width Li. In addition to the relationship Li > Lo in terms of groove width, the above relationship, i.e., Li < Xi and Li < Xo, is also required for the shoulder main grooves, which makes it possible to more effectively achieve both wet performance and handling stability.

[0054] It is preferable that the rib width Wc of the center land section is narrower than the rib width Wo of the second middle land section 33, which is mounted on the outside of the vehicle. In addition to the relationship Wi < Wo between the rib width of the first middle land section 32 and the rib width of the second middle land section 33, setting Wc < Wo for the rib width Wc of the center land section makes it possible to more effectively achieve both wet performance and handling stability.

[0055] [Shoulder Land Section] As shown in Figure 2, a shoulder land section 34 is provided between the shoulder main groove 23 and the ground contact end T. A shoulder land section 35 is provided between the shoulder main groove 24 and the ground contact end T.

[0056] The shoulder portion 34 is provided on the outer side in the tire width direction of the first middle portion 32. The shoulder portion 34 has a shoulder lug groove 61, a shallow groove 62, a shallow groove 62', and a circumferential narrow groove 63. The shoulder lug groove 61, the shallow groove 62, and the shallow groove 62' extend from within the tire contact end T of the shoulder portion 34 outward in the tire width direction and terminate outside the tire contact end T. A shallow groove is a groove with a groove depth of 1.0 [mm] or less at its deepest point.

[0057] Multiple shoulder lug grooves 61, shallow grooves 62, and shallow grooves 62' are provided in the circumferential direction of the tire. The shallow grooves 62 and shallow grooves 62' are provided alternately in the circumferential direction of the tire. The shallow grooves 62 communicate with the shoulder main groove 23. The shallow grooves 62' do not communicate with the shoulder main groove 23.

[0058] The circumferential narrow grooves 63 extend in the circumferential direction of the tire within the shoulder land portion 34, intersecting each shoulder lug groove 61 and each shallow groove 62, shallow groove 62'. The shoulder lug grooves 61, shallow grooves 62, and shallow groove 62' are in communication with the circumferential narrow grooves 63.

[0059] The shoulder portion 35 is provided on the outer side in the tire width direction of the second middle portion 33. The shoulder portion 35 has a shoulder lug groove 61, a shallow groove 62, and a shallow groove 62'. The shoulder lug groove 61, the shallow groove 62, and the shallow groove 62' extend from within the tire contact end T of the shoulder portion 35 outward in the tire width direction and terminate outside the tire contact end T.

[0060] Multiple shoulder lug grooves 61, shallow grooves 62, and shallow grooves 62' are provided in the circumferential direction of the tire. The shallow grooves 62 and 62' are provided alternately in the circumferential direction of the tire. The shallow grooves 62 communicate with the shoulder main groove 23. The shallow grooves 62' do not communicate with the shoulder main groove 23. The shallow grooves 62' have the same structure as the shallow grooves 62, except that they do not communicate with the shoulder main groove 23.

[0061] Figure 6 is an enlarged view of a portion B in Figure 2. As shown in Figure 6, the shoulder lug groove 61 consists of a main body portion 61a extending in the tire width direction and an end portion 61b connected to the main body portion 61a. The end portion 61b extends in a different direction from the main body portion 61a on the outside of the main body portion 61a in the tire width direction.

[0062] The shallow groove 62 has a first straight shallow groove 62a arranged substantially parallel to the main body portion 61a of the shoulder lug groove 61, and a second straight shallow groove 62b arranged substantially parallel to the end portion 61b of the shoulder lug groove 61. A bent portion 62c is provided between the first straight shallow groove 62a and the second straight shallow groove 62b. By providing the shoulder lug groove 61, the shallow groove 62 with the bent portion 62c, and the shallow groove 62', it is possible to improve steering stability by obtaining an edge effect while maintaining block rigidity.

[0063] Here, let Xa be the maximum width of the shoulder lug groove 61. Let Xb be the distance from the endpoint of the shoulder lug groove 61 on the first straight shallow groove 62a side to the endpoint of the first straight shallow groove 62a on the shoulder lug groove 61 side. In this case, it is preferable that the ratio Xa / Xb is 0.5 ≤ Xa / Xb ≤ 5.0.

[0064] Furthermore, it is more preferable that the ratio Xa / Xb is 0.8 ≤ Xa / Xb ≤ 3.0.

[0065] Figure 4 is a schematic diagram showing an example of a cross-section of section A-A in Figure 3, i.e., a cross-section of a chamfered sipe. Referring to Figure 4, 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.

[0066] Figure 5 schematically shows a cross-section of section A-A in Figure 3 in the contact state. As indicated by reference numeral 42a in Figure 5, 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.

[0067] The cross-sectional configuration of the non-chamfered sipes 42 and chamfered sipes 43 provided in the first middle land section 32 and the second middle land section 33 is the same as the configuration described with reference to Figures 4 and 5.

[0068] [Modification 1] In the above example, the case in which four circumferential main grooves 20 are arranged in the tire width direction was described, but the circumferential main grooves 20 may be arranged in three in the tire width direction. In that case, the tread portion will have the same configuration as the tread portion 2 shown in Figure 2, with the center land portion 31 removed (not shown). In this case, it is preferable that at least the middle land portion on the inner side of the mounting surface to the vehicle is provided with a sipe unit.

[0069] [Modification 2] Figure 7 shows a modified example of the tire of the present disclosure. Figure 7 shows the tread portion of the meridional section of the pneumatic tire according to the modification. In Figure 7, the reference profile 200 is shown by a dashed line. As shown in Figure 7, the contact surfaces of the center land portion 31', the middle land portion 32', and the middle land portion 33' are formed to protrude outward in the tire radial direction relative to the reference profile 200. By adopting a bulging profile that protrudes outward in the tire radial direction relative to the reference profile 200, the drainage effect of the sipe unit can be obtained more effectively, and the wet braking performance can be improved.

[0070] [Modification 3] The above describes the case in which the chamfered portion 430 is provided only on one side of the edge along the sipe portion 431, but the chamfered portions 430 may be provided on both sides of the edge along the sipe portion 431.

[0071] Figures 8 to 10 are cross-sectional views showing an example in which chamfered portions 430 are provided on both sides of the sipe portion 431. Figures 8 to 10 are schematic diagrams showing an example of a cross-section of a chamfered sipe.

[0072] The chamfered sipe 43a shown in Figure 8 is composed of a sipe portion 431 and chamfered portions 430a and 430b provided on both sides of the edge along the sipe portion 431. In the chamfered sipe 43a, a chamfered portion 430a is provided on one side along the sipe portion 431, and a chamfered portion 430b is provided on the other side. Therefore, compared to the case where a chamfered portion is provided on only one side, the volume of the groove is increased and the drainage performance is improved.

[0073] The chamfered sipe 43b shown in Figure 9 is composed of a sipe portion 431 and chamfered portions 430a and 430b provided on both sides of the edge along the sipe portion 431. Both the chamfered portions 430a and 430b of the chamfered sipe 43b are concave toward the center of the sipe portion 431. As a result, the volume of the groove can be made as large as possible compared to the chamfered sipe 43a shown in Figure 8, improving drainage performance.

[0074] The chamfered sipe 43c shown in Figure 10 is composed of a sipe portion 431 and chamfered portions 430a and 430b provided on both sides of the edge along the sipe portion 431. Both the chamfered portions 430a and 430b of the chamfered sipe 43c are convex toward the center of the sipe portion 431. As a result, the block rigidity is not reduced as much as the chamfered sipe 43a shown in Figure 8, and the drainage performance is improved compared to when it is provided on only one side.

[0075] [Example] Figures 11A to 11J are diagrams showing the results of performance tests of tires according to this embodiment. In this performance test, multiple types of test tires were evaluated for wet braking performance, dry handling stability performance, and crack propagation resistance. 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.

[0076] (1) The evaluation of wet braking performance involves the test vehicle driving on an asphalt road that has been sprayed with water to a depth of 1 mm, and measuring the braking distance from an initial speed of 80 km / h. Based on the measurement results, an index evaluation is performed by taking the reciprocal of Comparative Example 1 as the baseline (100). In terms of evaluation, a higher numerical value is preferable.

[0077] (2) 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 that takes the reciprocal of Comparative Example 1 as the baseline (100). In terms of evaluation, a higher numerical value is preferable.

[0078] (3) 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 reciprocal of the crack occurrence rate and crack growth rate was taken and expressed as an index. A higher number is preferable.

[0079] The test tires of each embodiment have the configurations shown in Figures 1 and 2. The conventional tire is a tire without sipe units. The tire of Comparative Example 1 has sipe units arranged in a staggered pattern, and the width of the rib on the inner side of the middle land portion when mounted on the vehicle is equal to the width of the rib on the outer side of the middle land portion when mounted on the vehicle. The tire of Comparative Example 2 has sipe units, but they are not arranged in a staggered pattern, and the chamfered sipes open on the same side in the tire width direction of the land portion.

[0080] As the test results show, the test tires for each embodiment showed good results in terms of wet braking performance, dry handling stability performance, and crack propagation resistance.

[0081] This disclosure encompasses the following inventions: [1] A tire for which the mounting direction to a vehicle is specified, comprising one or more center main grooves, a pair of shoulder main grooves provided on the outside of the center main groove in the tire width direction, a pair of shoulder land portions and first and second middle land portions partitioned by these main grooves, at least one of the first and second middle land portions having a plurality of chamfered sipes having a sipe portion and a chamfered portion, and non-chamfered sipes not having a chamfered portion, the chamfered sipes and non-chamfered sipes are arranged alternately in the tire circumferential direction, at least one of the first and second middle land portions having a plurality of sipe units composed of the non-chamfered sipes and the chamfered sipes, the sipe unit is a combination of the chamfered sipe on the side of the chamfered sipes located on both sides of the non-chamfered sipe in the tire circumferential direction that is closer to the non-chamfered sipe and the non-chamfered sipe, one end of the chamfered sipe opens into either the center main groove or the shoulder main groove, [1] The other end of the chamfered sipe terminates without opening into the center main groove and the shoulder main groove, and a plurality of the sipe units are arranged in the circumferential direction of the tire, with one end of the chamfered sipe of one adjacent sipe unit in the circumferential direction of the tire opening into the center main groove and the other end of the chamfered sipe opening into the shoulder main groove, and of the first and second middle land sections, the rib width Wi of the middle land section on the side mounted to the vehicle is narrower than the rib width Wo of the middle land section on the side mounted to the vehicle. [2] The tire according to [1], wherein the first middle land section and the second middle land section each have the sipe unit. [3] The tire according to [1] or [2], wherein the ratio of the rib width Wo to the rib width Wi, Wo / Wi, is 1.1 ≤ Wo / Wi ≤ 1.6. [4] A tire according to any one of [1] to [3], further comprising a first middle land portion and a shoulder land portion provided on the outer side in the tire width direction of the second middle land portion, wherein the shoulder land portion on the inner side when mounted on the vehicle has circumferential grooves extending in the tire circumferential direction.[5] The tire according to [4], wherein the shoulder land portion has a shoulder lug groove extending outward in the tire width direction, the shoulder lug groove consists of a main body portion extending in the tire width direction and an end portion connected to the main body portion, the end portion extends outward in the tire width direction of the main body portion in a direction different from that of the main body portion, and has a first straight shallow groove arranged substantially parallel to the main body portion and a second straight shallow groove arranged substantially parallel to the end portion, and a bend is provided between the first straight shallow groove and the second straight shallow groove. [6] The tire according to [5], wherein the maximum width of the shoulder lug groove is Xa, and the distance from the first straight shallow groove side end of the shoulder lug groove to the shoulder lug groove side end of the first straight shallow groove is Xb, the ratio Xa / Xb is 0.5 ≤ Xa / Xb ≤ 5.0. [7] The tire according to any one of [1] to [6], wherein the distance Zb from the non-chamfered sipe to the end of the chamfered portion of the chamfered sipe is Zb ≤ 20.0 [mm]. [8] The tire according to any one of [1] to [7], wherein the inclination angle θ of the chamfered sipe of the sipe unit with respect to the tire circumferential direction is 30 [deg] ≤ θ ≤ 80 [deg]. [9] The tire according to [8], wherein the inclination angle θ' of the non-chamfered sipe of the sipe unit with respect to the tire circumferential direction and the inclination angle θ are in a relationship of -10 [deg] ≤ θ - θ' ≤ 10 [deg].

[10] The tire according to any one of [1] to [9], wherein the ratio X / W of the tire width extension distance X of the sipe portion of the chamfered sipe to the rib width W of the land portion on which the chamfered sipe is provided is in a relationship of 0.40 ≤ X / W ≤ 0.90.

[11] The tire according to any one of [1] to

[10] , 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.

[12] The tire according to any one of [1] to

[11] , wherein 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 satisfies the condition 2.00 ≤ Zm / Zs ≤ 6.00, and the maximum width Zs satisfies the condition 0.5 [mm] ≤ Zs ≤ 1.5 [mm].

[13] A tire according to any one of [1] to

[12] , wherein 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 to the maximum width Zs of the sipe portion of the chamfered sipe 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].

[14] A tire according to any one of [1] to

[13] , wherein the groove width of the non-chamfered sipe is 0.5 [mm] or more and 1.5 [mm] or less, and 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 shoulder main groove and the center main groove.

[15] The tire according to any one of [1] to

[14] , wherein each middle land portion further includes a V-shaped shallow groove portion having a V-shape with its top facing in the circumferential direction of the tire, and adjacent V-shaped shallow groove portions in the circumferential direction of the tire are arranged with the orientation of the V-shape facing in opposite directions to each other.

[16] The tire according to any one of [1] to

[15] , which has a closed groove provided in the extending direction of the chamfered sipe, wherein the closed groove is not connected to the chamfered sipe.

[17] The tire according to any one of [1] to

[16] , which includes two center main grooves, wherein the groove width Li of the center main groove on the inside of the mounting to the vehicle is wider than the groove width Lo of the center main groove on the outside of the mounting to the vehicle.

[18] The tire according to

[17] , which includes two center main grooves, wherein the ratio Li / Lo of the groove width Li to the groove width Lo is 1.03 ≤ Li / Lo ≤ 1.30.

[19] The tire according to

[17] or

[18] , comprising a center land portion formed between a center main groove on the inner side of mounting to the vehicle and a center main groove on the outer side of mounting to the vehicle, wherein the center land portion has the sipe unit.

[20] The tire according to

[19] , wherein the center land portion, the first middle land portion and the second middle land portion are provided only with the sipe unit, or are provided only with the sipe unit, a V-shaped shallow groove portion having its top facing the circumferential direction of the tire, and a closed groove provided in the direction of extension of the chamfered sipe.

[21] The tire according to

[19] or

[20] , wherein the rib width Wc of the center land portion is narrower than the rib width Wo of the middle land portion on the outside of the mounting to the vehicle.

[22] The tire according to any one of

[17] to

[21] , wherein the groove width Xi of the shoulder main groove on the inside of the mounting to the vehicle is wider than the groove width Li, and the groove width Xo of the shoulder main groove on the outside of the mounting to the vehicle is wider than the groove width Li.

[23] The tire according to any one of

[19] to

[21] , wherein the contact surfaces of the center land portion and the middle land portion are formed to protrude outward in the tire radial direction relative to the reference profile.

[0082] 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. Contact surface 15. Bead core 16. Bead filler 20. Circumferential main groove 21. Inner center main groove 22. Outer center main groove 23. Inner shoulder main groove 24. Outer shoulder main groove 31, 31' Center land section 32, 32', 33, 33' Middle land section 34, 35 Shoulder land section 40. Sipe unit 41. Shallow groove section 42. Non-chamfered sipe 43, 43a, 43b, 43c. Chamfered sipe 44. Closed groove 61. Shoulder lug groove 61a. Main body section 61b. End section 62, 62'. Shallow groove 62a. First straight shallow groove 62b Second straight shallow groove 62c Bent section 63 Circumferential narrow grooves 430, 430a, 430b Chamfered section 431 Sipe section T Grounding end

Claims

1. A tire with a specified mounting direction for a vehicle, comprising 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 pair of shoulder land portions and first and second middle land portions partitioned by these main grooves, at least one of the first and second middle land portions having a plurality of chamfered sipes having a sipe portion and a chamfered portion, and non-chamfered sipes not having a chamfered portion, the chamfered sipes and non-chamfered sipes are arranged alternately in the tire circumferential direction, at least one of the first and second middle land portions having a plurality of sipe units composed of the non-chamfered sipes and the chamfered sipes, the sipe unit is a combination of the chamfered sipe on the side closer to the non-chamfered sipe among the chamfered sipes located on both sides of the non-chamfered sipe in the tire circumferential direction, and the non-chamfered sipe, one end of the chamfered sipe opens into either the center main groove or the shoulder main groove, The other end of the chamfered sipe terminates without opening into the center main groove and the shoulder main groove, a plurality of sipe units are arranged in the circumferential direction of the tire, one end of the chamfered sipe of one adjacent sipe unit in the circumferential direction of the tire opens into the center main groove, and the other end of the chamfered sipe opens into the shoulder main groove, and the rib width Wi of the middle land portion on the inner side of the first and second middle land portions mounted on the vehicle is narrower than the rib width Wo of the middle land portion on the outer side of the vehicle.

2. The tire according to claim 1, wherein the first middle land portion and the second middle land portion each have the sipe unit.

3. The tire according to claim 1 or claim 2, wherein the ratio of the rib width Wo to the rib width Wi, Wo / Wi, is 1.1 ≤ Wo / Wi ≤ 1.

6.

4. The tire according to any one of claims 1 to 3, wherein the shoulder portion on the inner side when mounted on the vehicle has circumferential grooves extending in the circumferential direction of the tire.

5. The tire according to claim 4, wherein the shoulder land portion has a shoulder lug groove extending outward in the tire width direction, the shoulder lug groove comprises a main body portion extending in the tire width direction and an end portion connected to the main body portion, the end portion extends outward from the main body portion in the tire width direction and in a direction different from the main body portion, and has a first straight shallow groove arranged substantially parallel to the main body portion and a second straight shallow groove arranged substantially parallel to the end portion, and a bend is provided between the first straight shallow groove and the second straight shallow groove.

6. The tire according to claim 5, wherein the maximum width of the shoulder lug groove is Xa, and the distance from the first straight shallow groove side endpoint of the shoulder lug groove to the shoulder lug groove side endpoint of the first straight shallow groove is Xb, and the ratio Xa / Xb is 0.5 ≤ Xa / Xb ≤ 5.

0.

7. The tire according to any one of claims 1 to 6, wherein the distance Zb from the non-chamfered sipe to the end of the chamfered portion of the chamfered sipe is Zb ≤ 20.0 [mm].

8. The tire according to any one of claims 1 to 7, wherein the inclination angle θ of the chamfered sipe of the sipe unit with respect to the tire circumferential direction is 30 [deg] ≤ θ ≤ 80 [deg].

9. The tire according to claim 8, wherein the inclination angle θ' of the non-chamfered sipe of the sipe unit with respect to the tire circumferential direction and the inclination angle θ are related by -10 [deg] ≤ θ - θ' ≤ 10 [deg].

10. The tire according to any one of claims 1 to 9, wherein the ratio X / W of the tire width direction extension distance X of the sipe portion of the chamfered sipe to the rib width W of the land portion on which the chamfered sipe is provided satisfies the relationship 0.40 ≤ X / W ≤ 0.

90.

11. The tire according to any one of claims 1 to 10, 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.

12. The tire according to any one of claims 1 to 11, wherein 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 satisfies the condition 2.00 ≤ Zm / Zs ≤ 6.00, and the maximum width Zs satisfies the condition 0.5 [mm] ≤ Zs ≤ 1.5 [mm].

13. The tire according to any one of claims 1 to 12, wherein 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 to the maximum width Zs of the sipe portion of the chamfered sipe 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].

14. The tire according to any one of claims 1 to 13, wherein the groove width of the non-chamfered sipe is 0.5 mm or more and 1.5 mm or less, and 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 shoulder main groove and the center main groove.

15. The tire according to any one of claims 1 to 14, wherein each middle land portion further includes a V-shaped shallow groove portion having a V-shape with its top facing in the circumferential direction of the tire, and adjacent V-shaped shallow groove portions in the circumferential direction of the tire are arranged with the orientation of the V-shape facing in opposite directions to each other.

16. A tire according to any one of claims 1 to 15, having a closing groove provided in the extending direction of the chamfered sipe, wherein the closing groove is not connected to the chamfered sipe.

17. A tire according to any one of claims 1 to 16, comprising two center main grooves, wherein the groove width Li of the center main groove on the inner side when mounted on the vehicle is wider than the groove width Lo of the center main groove on the outer side when mounted on the vehicle.

18. The tire according to claim 17, which includes two center main grooves, wherein the ratio of the groove width Li to the groove width Lo, Li / Lo, is 1.03 ≤ Li / Lo ≤ 1.

30.

19. The tire according to claim 17 or 18, comprising a center land portion formed between a center main groove on the inner side of mounting to the vehicle and a center main groove on the outer side of mounting to the vehicle, wherein the center land portion has the sipe unit.

20. The tire according to claim 19, wherein the center land portion, the first middle land portion, and the second middle land portion are provided with only the sipe unit, or are provided with only the sipe unit, a V-shaped shallow groove portion having a V-shape with its top facing the circumferential direction of the tire, and a closed groove provided in the direction of extension of the chamfered sipe.

21. The tire according to claim 19 or claim 20, wherein the rib width Wc of the center land portion is narrower than the rib width Wo of the middle land portion on the outer side of the mounting to the vehicle.

22. The tire according to any one of claims 17 to 21, wherein the groove width Xi of the shoulder main groove on the inner side when mounted on the vehicle is wider than the groove width Li, and the groove width Xo of the shoulder main groove on the outer side when mounted on the vehicle is wider than the groove width Li.

23. The tire according to any one of claims 19 to 21, wherein the contact surfaces of the center land portion and the middle land portion are formed to protrude outward in the radial direction of the tire relative to the reference profile.

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