Tire

Abstract

The invention provides a tire which maintains dry performance and improves performance on ice and snow. The grooves (3) provided in the tread portion (2) include a plurality of first inclined grooves (6), a plurality of second inclined grooves (7), a plurality of first shoulder longitudinal grooves (8), and a plurality of first crown longitudinal grooves (11). The plurality of first inclined grooves (6) are respectively communicated with the second inclined grooves (7) and form terminals. The plurality of second inclined grooves (7) are respectively communicated with the first inclined grooves (6) and form terminals. The plurality of pattern blocks (4) include a plurality of crown pattern blocks (15), a plurality of first shoulder pattern blocks (18), and a plurality of first middle pattern blocks (16). A plurality of sipes (10) are formed on the respective tread surfaces of the pattern blocks (4). The sipe density SDc of the crown block (15), the sipe density SDm of the first middle block (16), and the sipe density SDs of the first shoulder block (18) satisfy SDc > SDs and SDm > SDs.

Description

Technical Field

[0001] The present invention relates to tires. Background Art

[0002] For example, Patent Document 1 below proposes a tire having a tread portion provided with a plurality of first inclined grooves, a plurality of second inclined grooves, and a plurality of first longitudinal grooves connecting two of the first inclined grooves. By specifying the groove width of the first longitudinal grooves, this tire is expected to maintain dry performance while improving performance on ice and snow.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-080118

[0004] In recent years, with the improvement of vehicle performance, all-season tires used on both dry roads and icy and snowy roads are also required to further enhance their performance on ice and snow. One approach to improving performance on ice and snow is to configure a large number of sipes in the land portion of the tread. However, this approach can sometimes result in an excessive reduction in land portion rigidity, depending on the sipe placement, impairing dry performance. Summary of the Invention

[0005] The present invention has been made in view of the above-mentioned actual situation, and a main object of the present invention is to provide a tire that maintains dry performance while improving performance on ice and snow.

[0006] The present invention is a tire having a tread portion with a designated rotational direction, the tread portion comprising: a first tread end and a second tread end, a plurality of grooves arranged between the first tread end and the second tread end, and a plurality of pattern blocks divided by the plurality of grooves, the plurality of grooves comprising: a plurality of first inclined grooves extending obliquely from at least the first tread end toward the first ground contact side in the rotational direction as they approach the tire equator; a plurality of second inclined grooves extending obliquely from at least the second tread end toward the first ground contact side in the rotational direction as they approach the tire equator; a plurality of first shoulder longitudinal grooves connected to two of the first inclined grooves adjacent in the tire circumferential direction and extending along the tire circumferential direction; and a plurality of first crown longitudinal grooves arranged between the plurality of first shoulder longitudinal grooves and the tire equator and connected to the two first inclined grooves. The first inclined grooves are respectively connected to any one of the plurality of second inclined grooves and form a terminal, the plurality of second inclined grooves are respectively connected to any one of the plurality of first inclined grooves and form a terminal, the plurality of pattern blocks include: a plurality of crown pattern blocks, which are arranged on the tire equator; a plurality of first shoulder pattern blocks, which include the first tread end and are divided by the two first inclined grooves and the first shoulder longitudinal groove; and a plurality of first intermediate pattern blocks, which are arranged between the plurality of crown pattern blocks and the plurality of first shoulder pattern blocks, and a plurality of sipes are respectively formed on the tread of the first shoulder pattern block, the tread of the first intermediate pattern block and the tread of the crown pattern block. For each pattern block, the total length (mm) of the plurality of sipes formed on the tread is divided by the area (mm) of the tread. 2 ) and the obtained value is set as the tool groove density (mm / mm 2 ), the sipe density SDc of the crown block, the sipe density SDm of the first middle block, and the sipe density SDs of the first shoulder block satisfy SDc>SDs and SDm>SDs.

[0007] The tire of the present invention, by adopting the above-described structure, can maintain dry performance while improving performance on ice and snow. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a development view of the tread portion of a tire according to one embodiment of the present invention.

[0009] Figure 2 yes Figure 1 Enlarged view of the crown block, first middle block and shoulder blocks.

[0010] Figure 3 This is a graph conceptually showing the rigidity distribution of the tread portion of various tires.

[0011] Figure 4 yes Figure 2 An enlarged cross-sectional view of the first shoulder sipe along the longitudinal direction.

[0012] Figure 5 yes Figure 2 An enlarged cross-sectional view of the second shoulder sipe along the longitudinal direction.

[0013] Figure 6 yes Figure 2 An enlarged cross-sectional view of the middle sipe along the length direction.

[0014] Figure 7 yes Figure 2 An enlarged cross-sectional view of a shallow sipe along the length direction.

[0015] Figure 8 yes Figure 1 An enlarged view of the outline of the first inclined groove.

[0016] Figure 9 It is a development view of the tread portion of a tire of a comparative example.

[0017] Description of Reference Numerals

[0018] 2...tread portion; 3...groove; 4...block; 6...1st oblique groove; 7...2nd oblique groove; 8...1st shoulder longitudinal groove; 10...sipe; 11...1st crown longitudinal groove; 15...crown block; 16...1st middle block; 18...1st shoulder block; R...rotational direction; T1...1st tread end; T2...2nd tread end; SDc...sipe density of the crown block; SDm...sipe density of the first middle block; SDs...sipe density of the first shoulder block. DETAILED DESCRIPTION

[0019] An embodiment of the present invention is described below with reference to the accompanying drawings. The drawings describe the features of the present invention, but to aid understanding of the present invention, they sometimes include exaggerated representations or dimensional ratios that differ from the actual structure. Furthermore, throughout the various embodiments, identical or shared elements are denoted by the same reference numerals, and duplicate descriptions are omitted. Furthermore, structures not described in this specification may be appropriately adapted from known structures.

[0020] Figure 1 FIG. 2 shows a development view of the tread portion 2 of the tire 1 according to the present embodiment. Figure 1 As shown, the tire 1 of this embodiment is a pneumatic tire for passenger cars and is used as a so-called all-season tire that achieves both sufficient dry performance and performance on ice and snow. However, the tire of the present invention is not limited to this embodiment.

[0021] The tire 1 of the present invention includes a tread portion 2 to which a rotation direction R is specified. The rotation direction R is indicated on a sidewall portion (not shown) by, for example, characters or symbols.

[0022] The tread portion 2 of the tire 1 of this embodiment includes a first tread end T1 and a second tread end T2. In the various figures of this specification, the tread end on the left side of the tire equator C is referred to as the first tread end T1, and the tread end on the right side of the tire equator C is referred to as the second tread end T2. The tread portion 2 includes a first tread portion 2A between the tire equator C and the first tread end T1, and a second tread portion 2B between the tire equator C and the second tread end T2. The first tread portion 2A and the second tread portion 2B are substantially line-symmetrical about the tire equator C, except for being offset in the tire circumferential direction. Therefore, the various structures of the first tread portion 2A can be applied to the second tread portion 2B.

[0023] The first tread end T1 and the second tread end T2 correspond to the ends of the ground contact surface when 70% of the normal load is applied to the tire 1 in a normal state and the tread portion 2 contacts a flat surface at a camber angle of 0°.

[0024] For pneumatic tires with specified specifications, the "normal condition" refers to the tire being assembled on a standard rim, inflated to a specified internal pressure, and unloaded. For tires without specified specifications, the "normal condition" refers to the standard usage condition corresponding to the tire's intended use, unmounted on a vehicle, and unloaded. Unless otherwise specified in this specification, dimensions of various tire components are values measured under this normal condition.

[0025] "Regular rims" are rims whose specifications are specified for each tire within the standard system that includes the tire's specifications. For example, JATMA refers to them as "standard rims," TRA refers to them as "design rims," and ETRTO refers to them as "measuring rims."

[0026] "Normal internal pressure" refers to the air pressure specified for each tire within the specification system that includes the tire's specifications. For JATMA, it is the "maximum air pressure." For TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES." For ETRTO, it is "INFLATION PRESSURE."

[0027] For pneumatic tires with various specifications, the "Normal Load" refers to the load specified for each tire within the standard system that includes the tire's specifications. For JATMA, this refers to the "Maximum Load Capacity," for TRA, it refers to the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table, and for ETRTO, it refers to "LOAD CAPACITY." If tires with no specific specifications are specified, the "Normal Load" refers to the maximum load applicable when the tire is used within the aforementioned specifications.

[0028] The tread portion 2 includes a plurality of grooves 3 provided between a first tread end T1 and a second tread end T2 , and a plurality of blocks 4 defined by the plurality of grooves 3 .

[0029] The plurality of grooves 3 include a plurality of first inclined grooves 6, a plurality of second inclined grooves 7, a plurality of first shoulder longitudinal grooves 8, and a plurality of first crown longitudinal grooves 11. The first inclined grooves 6 extend obliquely from at least the first tread end T1 toward the tire equator C, toward the first contact side in the rotational direction R. The second inclined grooves 7 extend obliquely from at least the second tread end T2 toward the tire equator C, toward the first contact side in the rotational direction R. The first inclined grooves 6 and the second inclined grooves 7 each have a groove width W1 of 2 to 12 mm. Furthermore, the first inclined grooves 6 and the second inclined grooves 7 each have a depth of 5 to 12 mm.

[0030] In addition, when numerical ranges for various parameters are described in this specification, unless otherwise specified, these numerical ranges refer to the average values for that parameter. Therefore, the numerical ranges for the width and depth of the inclined grooves described above refer to the average values of the width and depth measured at various locations within the inclined grooves. The same applies to the other parameters described below.

[0031] The first shoulder longitudinal groove 8 communicates with two adjacent first oblique grooves 6 in the tire circumferential direction and extends in the tire circumferential direction. The first crown longitudinal groove 11 is disposed between the first shoulder longitudinal groove 8 and the tire equator C and communicates with the two first oblique grooves 6.

[0032] In the present embodiment, the plurality of grooves 3 include a plurality of second shoulder longitudinal grooves 9 and a plurality of second crown longitudinal grooves 12 provided in the second tread portion 2B. The second shoulder longitudinal grooves 9 have substantially the same features as the first shoulder longitudinal grooves 8. In addition, the second crown longitudinal grooves 12 have substantially the same features as the first crown longitudinal grooves 11. Therefore, the features of the first shoulder longitudinal grooves 8 described below can also be applied to the second shoulder longitudinal grooves 9. The same relationship also applies to the first crown longitudinal grooves 11 and the second crown longitudinal grooves 12.

[0033] In the present invention, each of the plurality of first inclined grooves 6 communicates with and terminates in any one of the plurality of second inclined grooves 7. Furthermore, each of the plurality of second inclined grooves 7 communicates with and terminates in any one of the plurality of first inclined grooves 6.

[0034] The plurality of tread blocks 4 include a crown block 15, first shoulder blocks 18, and a first center block 16. The crown blocks 15 of this embodiment include first crown blocks 15A and second crown blocks 15B, which are arranged alternately in the tire circumferential direction. The first crown block 15A is defined by two first oblique grooves 6, one second oblique groove 7, and one first crown longitudinal groove 11. The second crown block 15B is defined by two second oblique grooves 7, one first oblique groove 6, and one second crown longitudinal groove 12.

[0035] The first shoulder block 18 includes a first tread end T1 and is defined by two first oblique grooves 6 and a first shoulder longitudinal groove 8. The first middle block 16 is provided between the plurality of crown blocks 15 and the plurality of first shoulder blocks 18.

[0036] The tread blocks 4 of this embodiment further include a second shoulder block 19 and a second middle block 17. The second shoulder block 19 has substantially the same features as the first shoulder block 18. The second middle block 17 has substantially the same features as the first middle block 16. Therefore, the features of the first shoulder block 18 described below also apply to the second shoulder block 19. The same relationship also applies to the first middle block 16 and the second middle block 17.

[0037] Figure 2 FIG. 1 shows an enlarged view of the crown block 15, the first middle block 16, and the first shoulder block 18. Figure 2 As shown, a plurality of sipes 10 are formed on the tread surface 18s of the first shoulder block 18, the tread surface 16s of the first middle block 16, and the tread surface 15s of the crown block 15. Hereinafter, the sipes 10 provided in the crown block 15 may be referred to as crown sipes 21, the sipes 10 provided in the first middle block 16 may be referred to as middle sipes 23, and the sipes 10 provided in the first shoulder block 18 may be referred to as shoulder sipes 25.

[0038] In this specification, a "sipe" is a groove having a small width, and refers to an element capable of maintaining the rigidity of the pattern block by contacting the two sipe walls contained in the sipe main body when a ground load acts on the tread portion 2. The above-mentioned sipe main body refers to a portion in which the two sipe walls are substantially parallel to each other (for example, less than 10°) and extend in the radial direction of the tire. In addition, from the viewpoint of exerting the above-mentioned effect, the width between the two sipe walls at the sipe main body is, for example, less than 1.5 mm, preferably 0.4 to 1.2 mm, and more preferably 0.4 to 1.0 mm. The sipe of this embodiment extends with a constant width from its opening to the bottom. However, the sipe may also have a chamfered portion formed at its edge. In addition, the sipe may also have a so-called flask bottom whose width is expanded at its bottom.

[0039] For each block, the total length (mm) of the plurality of sipes 10 formed on the tread is divided by the area (mm) of the tread. 2 ) and the obtained value is set as the tool groove density (mm / mm 2 ), in the present invention, the sipe density SDc of the crown block 15, the sipe density SDm of the first middle block 16, and the sipe density SDs of the first shoulder block 18 satisfy the following equations (1) and (2). Thus, the tire of the present invention can maintain dry performance while improving performance on ice and snow. The reasons for this are as follows.

[0040] SDc>SDs…(1)

[0041] SDm>SDs…(2)

[0042] like Figure 1 As shown, in the tire 1 of the present invention, the plurality of first inclined grooves 6 each communicate with and terminate in any one of the plurality of second inclined grooves 7. Furthermore, the plurality of second inclined grooves 7 each communicate with and terminate in any one of the plurality of first inclined grooves 6. Therefore, when the tire 1 of the present invention travels on icy or snowy roads, the connecting portions of these grooves strongly compact the snow, exerting a strong snow column shear force. Furthermore, since the tread of each tread block is provided with multiple sipes 10, their edges provide high friction even on icy or snowy roads. This improves performance on icy or snowy roads.

[0043] Figure 3 A graph conceptually showing the rigidity distribution of the tread portion of various tires is shown. Figure 3 The horizontal axis P represents the position of the tread portion in the tire axial direction, the center position corresponds to the tire equator C, the left side corresponds to the first tread end T1 side, and the right side corresponds to the second tread end T2 side. Figure 3 The vertical axis S represents the rigidity of each part. Figure 3Curve GR1 represents the above-mentioned rigidity distribution of a conventional studless tire. Curve GR2 represents the above-mentioned rigidity distribution of a conventional summer tire. Curve GR3 represents the above-mentioned rigidity distribution of the tire 1 of this embodiment.

[0044] If you can from Figure 3 As can be seen from the graphs GR1 and GR2, studless tires that prioritize performance on ice and snow have a large number of sipes in the tread, resulting in a low overall tread rigidity. On the other hand, conventional summer tires, which are not designed for driving on ice and snow and prioritize dry performance, have a relatively high tread rigidity.

[0045] The inventors have carefully studied the contribution of various tread components during driving on dry roads and on icy and snowy roads. As a result, they have come to the conclusion that maintaining the rigidity of the shoulder blocks is preferable to maintaining dry performance, while reducing the rigidity of the center and crown blocks by providing a large number of sipes to improve performance on icy and snowy roads.

[0046] Based on this understanding, in the present invention, the sipe density of each tread block satisfies the above-mentioned formula (1) and formula (2). Figure 3 As shown by the curve GR3, the first shoulder blocks 18 exert high rigidity to maintain dry performance. Meanwhile, the first middle blocks 16 and the crown blocks 15 provide high friction through the sipes 10, thereby improving performance on snow and ice. Due to this mechanism, the tire 1 of the present invention maintains dry performance while improving performance on snow and ice compared to conventional all-season tires.

[0047] like Figure 2 As shown, from the viewpoint of improving the dry performance and the performance on ice and snow in a balanced manner, the sipe density SDs of the first shoulder block 18 is, for example, 0.10 to 0.15 mm / mm. 2 , preferably 0.12~0.14mm / mm 2 Similarly, the sipe density SDc of the crown block 15 and the sipe density SDm of the first middle block 16 are, for example, 0.17 to 0.23 mm / mm, respectively. 2 , preferably 0.20~0.22mm / mm 2 .

[0048] Furthermore, it is preferable that the sipe density SDc of the crown block 15 and the sipe density SDm of the first middle block 16 are each 140% to 160% of the sipe density SDs. This prevents uneven wear of the first middle block 16 and the crown block 15, while also providing excellent performance on ice and snow.

[0049] The sipe density SDc of the crown block 15 is preferably 80% to 120% of the sipe density SDm of the first middle block 16. This further suppresses uneven wear of these blocks.

[0050] The following describes the structure of this embodiment in more detail. The various structures described below represent specific aspects of this embodiment. Therefore, it goes without saying that the present invention can achieve the aforementioned effects even without the structures described below. Furthermore, even if any one of the structures described below is applied individually to the tire 1 of the present invention having the aforementioned features, performance improvements corresponding to each structure can be expected. Furthermore, when several of the structures described below are applied in combination, performance improvements corresponding to the aforementioned structures can be achieved.

[0051] like Figure 1 As shown, the tread portion 2 includes a tread rubber 2G that forms the tread surface of the tread blocks 4. To achieve a balanced improvement in dry performance and performance on snow and ice, the rubber hardness of the tread rubber 2G is, for example, 50 to 65 degrees. In this specification, the rubber hardness refers to the Durometer A hardness measured at 23°C in accordance with JIS-K6253.

[0052] From the same perspective, the land ratio of the tread portion 2 is 65% to 75%. In this specification, the "land ratio" corresponds to the ratio of the actual contact area to the virtual contact area when the grooves and sipes of the tread portion 2 are completely filled.

[0053] Conventional all-season tires often have a tread width of approximately 65% to 70% of the tire's nominal width, due to a slight emphasis on wet performance. In contrast, the tread width TW of the tire 1 of this embodiment is set at 75% to 85% of the tire's nominal width, and more preferably, at least 80%. This provides the tread portion 2 with a sufficiently large contact patch, enabling excellent grip on both dry and icy roads. The nominal tire width described above corresponds to the nominal cross-sectional width of the tire. For example, if the tire size is "195 / 65R15," the nominal width is 195 mm.

[0054] The tread portion 2 is provided with multiple V-shaped block groups 5 along the tire circumference. Each of these V-shaped block groups 5 includes a crown block 15, a first middle block 16, a second middle block 17, a first shoulder block 18, and a second shoulder block 19. The tread portion 2 of this embodiment comprises 55 to 78 of these block groups 5 along the entire circumference of the tire. However, the present invention is not limited to this embodiment.

[0055] like Figure 2As shown, the plurality of sipes 10 are arranged at an angle of 15° or less relative to the tire's axial direction. This configuration means that the imaginary straight line connecting the ends of the sipes 10 forms an angle of 15° or less relative to the tire's axial direction. In a preferred embodiment, all sipes 10 provided in the tread portion 2 are arranged in this manner. This arrangement reliably improves traction and braking performance on icy and snowy roads, which are particularly important for all-season tires.

[0056] The sipes 10 of this embodiment include sipes 10A extending in a zigzag pattern when viewed from above the tread, and sipes 10B extending in a straight line. The zigzag sipes 10A oscillate in a zigzag pattern even in a cross-section perpendicular to their longitudinal direction, extending in the tire radial direction, forming so-called 3D sipes. When ground pressure is applied to the zigzag sipes 10A, the two sipe walls engage and contact each other, effectively maintaining block rigidity.

[0057] The first shoulder block 18 is provided with a plurality of first shoulder sipes 26 and a plurality of second shoulder sipes 27. The first shoulder sipes 26 extend linearly from a longitudinal narrow groove 30 (described later) to at least the first tread end T1. The second shoulder sipes 27 extend in a zigzag pattern from the first shoulder longitudinal groove 8 to the longitudinal narrow groove 30. Two to four first shoulder sipes 26 are arranged along the tire circumferential direction in one first shoulder block 18. The same applies to the second shoulder sipes 27. Thus, four to eight sipes 10 are arranged in one first shoulder block 18.

[0058] Figure 4 FIG. 2 shows an enlarged cross-sectional view of the first shoulder sipe 26 along the longitudinal direction. Figure 4 As shown, the depth of the first shoulder sipe 26 gradually decreases as it moves from the end on the tire equator C side toward the first tread end T1. The first shoulder sipe 26 includes a first portion 26a, a second portion 26b, and a third portion 26c, each of which has varying depths as it moves from the end on the longitudinal fine groove 30 side toward the end on the first tread end T1 side. The first portion 26a has a depth d1, which is the maximum depth of the sipe. This depth d1 is, for example, 65% to 80% of the maximum depth of the first inclined groove 6 (not shown). Furthermore, the length of the first portion 26a when viewed from above the tread (the so-called periphery length along the longitudinal direction of the sipe, referred to hereinafter as the same) is, for example, 25% to 35% of the overall length of the first shoulder sipe 26 on the tread surface 18s of the first shoulder block 18.

[0059] The second portion 26b has a depth d2 that is smaller than the depth d1. The depth d2 is, for example, 60% to 75% of the depth d1. Furthermore, the length of the second portion 26b, when viewed from above the tread, is 25% to 35% of the overall length of the first shoulder sipe 26. The third portion 26c has a depth d3 that is smaller than the depth d2. The depth d3 is, for example, 25% to 40% of the depth d1. Furthermore, the length of the third portion 26c, when viewed from above the tread, is 25% to 35% of the overall length of the first shoulder sipe 26. The first shoulder sipe 26 having such a depth distribution helps to achieve a balanced improvement in dry performance and performance on ice and snow.

[0060] Figure 5 FIG2 shows an enlarged cross-sectional view of the second shoulder sipe 27 along the longitudinal direction. The second shoulder sipe 27 extends in a zigzag shape, so its sipe wall includes concave and convex and ridges that serve as its boundaries. Figure 5 The same is true for the other cross-sectional views of the sipes in this specification. Figure 5 As shown, the second shoulder siping 27 includes a first portion 27a, a second portion 27b, and a third portion 27c having different depths from the end on the first shoulder longitudinal groove 8 side toward the end on the longitudinal narrow groove 30 side.

[0061] The first portion 27a of the second shoulder sipe 27 communicates with the first shoulder longitudinal groove 8 and has the smallest depth. The second portion 27b has the maximum depth d5 of the second shoulder sipe 27. The depth d4 of the first portion 27a is 25% to 35% of the depth d5 of the second portion 27b. Furthermore, the third portion 27c has a depth d6 that is greater than the depth d4 of the first portion 27a and less than the depth d5 of the second portion 27b. The depth d6 of the third portion 27c is, for example, 60% to 70% of the depth d5 of the second portion 27b. The second shoulder sipe 27 with this depth distribution can prevent excessive opening at the end on the first shoulder longitudinal groove 8 side, thereby effectively maintaining dry performance.

[0062] Furthermore, the length of the first portion 27a when viewed from above the tread is 10% to 25% of the overall length of the second shoulder sipe 27. The length of the second portion 27b when viewed from above the tread is 25% to 35% of the overall length of the second shoulder sipe 27. The length of the third portion 27c when viewed from above the tread is 40% to 60% of the overall length of the second shoulder sipe 27.

[0063] Figure 6 FIG. 2 shows an enlarged cross-sectional view of the middle sipe 23 along the length direction. Figure 6As shown, the middle sipe 23 has shallow bottoms 23a formed at both ends. The depth d8 of the shallow bottoms 23a is, for example, 20% to 35% of the maximum depth d7 of the middle sipe 23. Such a middle sipe 23 can prevent opening at both ends, reliably maintain dry performance, and improve performance on ice and snow. In addition, this cross-sectional shape can also be used for the crown sipe 21 ( Figure 2 shown).

[0064] like Figure 2 As shown, a plurality of sipes 10 extending in the tire axial direction are arranged along the tire circumferential direction in the first middle block 16 and the crown block 15. Among these sipes 10, those provided on the end sides of the tread blocks in the tire circumferential direction are preferably configured as shallow sipes 32. Figure 7 FIG. 3 shows an enlarged cross-sectional view of the shallow bottom sipe 32 along the length direction. Figure 7 As shown, the shallow sipes 32 have a depth d9 of, for example, 0.5 to 2.0 mm. Such shallow sipes 32 are arranged at the ends of the blocks, thereby preventing damage such as chipping of the blocks.

[0065] Figure 8 Show Figure 1 The enlarged view of the outline of the first inclined groove 6. Figure 8 In the figure, the sipes provided on the land portion are omitted. Figure 8 As shown, the plurality of first inclined grooves 6 include, for example, first inclined grooves 6 arranged alternately in the tire circumferential direction and closer to the second tread end T2 than the tire equator C. Figure 1 The main first inclined groove 6a is interrupted at the position on the tire side (as shown) and the auxiliary first inclined groove 6b is terminated without crossing the tire equator C.

[0066] The angle of the first inclined groove 6 with respect to the tire axial direction increases, for example, toward the tire equator C. Such first inclined groove 6 provides snow shearing forces in multiple directions, contributing to improved traction and cornering performance on snow.

[0067] The first inclined groove 6 includes, for example, a plurality of groove portions extending linearly and inclined relative to the tire axial direction. Preferably, the total length of the linearly extending groove edge of the first inclined groove 6 in this embodiment is at least 80% of the total length of the entire groove edge.

[0068] The first inclined groove 6 includes, for example, a first groove portion 36, a second groove portion 37, and a third groove portion 38. The first groove portion 36, for example, extends linearly and is inclined relative to the tire axial direction from at least the first tread end T1. The second groove portion 37 is connected to the first groove portion 36 and extends linearly at a greater angle relative to the tire axial direction than the first groove portion 36. The third groove portion 38 is connected to the second groove portion 37 and extends at a greater angle relative to the tire axial direction than the second groove portion 37. In this embodiment, the third groove portion 38 of the main first inclined groove 6a crosses the tire equator C and communicates with the second inclined groove 7, while the third groove portion 38 of the auxiliary first inclined groove 6b does not cross the tire equator C and communicates with the second inclined groove 7.

[0069] The angle θ1 of the first groove portion 36 relative to the tire axial direction is, for example, 5 to 15 degrees. The angle θ2 of the second groove portion relative to the tire axial direction is, for example, 25 to 35 degrees. The angle θ3 of the third groove portion 38 relative to the tire axial direction is, for example, 45 to 60 degrees. As a result, when driving on icy or snowy roads, the edges of each groove portion exert friction in multiple directions, achieving excellent performance on ice and snow.

[0070] The groove width W1 of the first oblique groove 6 preferably decreases from the first tread end T1 side toward the tire equator C side. This facilitates guiding water in the first oblique groove 6 toward the first tread end T1 side during wet running, thereby improving wet performance.

[0071] The first shoulder longitudinal groove 8 has an end portion on the first contact side in the rotational direction R connected to the groove edge of the first groove portion 36 and the groove edge of the second groove portion 37 of the first inclined groove 6. In addition, the end portion on the rear contact side in the rotational direction R of the first shoulder longitudinal groove 8 is connected to the groove edge of the second groove portion 37 of the first inclined groove 6. Thus, the first shoulder longitudinal groove 8 is inclined toward the first tread end T1 as it moves toward the first contact side in the rotational direction R. The angle θ4 of the first shoulder longitudinal groove 8 relative to the tire circumferential direction is, for example, 5 to 15 degrees. Such a first shoulder longitudinal groove 8 can provide a large frictional force in the tire axial direction.

[0072] The groove width of the first shoulder longitudinal groove 8 preferably increases continuously toward the ground contact side in the rotational direction R. Furthermore, the groove width W3 of the first shoulder longitudinal groove 8 is preferably 50% to 70% of the maximum groove width W2 of the first oblique groove 6. Such first shoulder longitudinal grooves 8 can strongly compact snow within them as the tire rotates, exerting a large snow column shear force.

[0073] The first crown longitudinal groove 11 is connected to the third groove portion 38 of each of the two first oblique grooves 6. Figure 2 As shown in FIG, the first crown longitudinal groove 11 divides the crown block 15 and the first middle block 16. In addition, the first crown longitudinal groove 11 is inclined toward the first tread end T1 side as it moves toward the first ground contact side in the rotation direction R. Figure 8As shown, the angle θ5 of the first crown longitudinal groove 11 relative to the tire circumferential direction is, for example, 25 to 35. Such first crown longitudinal groove 11 can exert frictional force in a balanced manner in the tire axial direction and the tire circumferential direction when running on icy or snowy roads.

[0074] In this embodiment, the first shoulder block 18 is provided with, for example, a single longitudinal narrow groove 30. The longitudinal narrow groove 30 communicates with the first groove portion 36 of each of the two first inclined grooves 6 and extends in the tire circumferential direction. The longitudinal narrow groove 30 inclines toward the first tread end T1 as it approaches the leading contact side in the rotational direction R. The angle θ6 of the longitudinal narrow groove 30 with respect to the tire circumferential direction is preferably greater than the aforementioned angle θ4 of the first shoulder longitudinal groove 8. Specifically, the angle θ6 of the longitudinal narrow groove 30 is between 10 and 25 degrees.

[0075] The longitudinal narrow grooves 30 extend linearly with a constant width W4. The width W4 of the longitudinal narrow grooves 30 is smaller than the width W3 of the first shoulder longitudinal grooves 8 and smaller than the width of the first crown longitudinal grooves 11. In a preferred embodiment, the width W4 of the longitudinal narrow grooves 30 is 10% to 20% of the width W3 of the first shoulder longitudinal grooves 8. Such longitudinal narrow grooves 30 reliably maintain dry performance.

[0076] like Figure 2 As shown, the first shoulder sipe 26 and the second shoulder sipe 27 communicate with the longitudinal narrow groove 30. However, the tire 1 of the present invention is not limited to this embodiment.

[0077] like Figure 8 As shown, the first middle block 16 of this embodiment is provided with a single middle short groove 40 that communicates with one of the first inclined grooves 6 and has a closed end within the tread surface 16s. In a preferred embodiment, the middle short groove 40 communicating with the auxiliary first inclined groove 6b overlaps with a region formed by extending the first crown longitudinal groove 11 communicating with the auxiliary first inclined groove 6b in its longitudinal direction. This groove arrangement allows the auxiliary first inclined groove 6b and the middle short groove 40 to form a hard snow column when driving on icy or snowy roads, further improving performance on ice and snow.

[0078] As mentioned above, the tire according to one embodiment of the present invention has been described in detail, but the present invention is not limited to the above-mentioned specific embodiment and can be implemented in various modified forms.

[0079] Example

[0080] Based on the specifications in Table 1 and 2, we have produced Figure 1 A pneumatic tire with a size of 195 / 65R15 and a tread pattern as shown in FIG. Figure 9 Tires with the tread pattern shown. Figure 9As shown in FIG. 1 , in the tire of the comparative example, the sipe density SDc of the crown block a and the sipe density SDm of the first middle block b are smaller than the sipe density SDs of the first shoulder block c. Figure 1 The tires shown are essentially identical. Each tire was tested for dry performance and performance on ice and snow. The common specifications and testing methods for each tire are as follows.

[0081] Test vehicle: 1800cc displacement, front-wheel drive

[0082] Test tire mounting position: All wheels

[0083] Rim: 15×6.0

[0084] Tire pressure: front wheel 230kPa, rear wheel 240kPa

[0085] <Dry performance>

[0086] The driver's sensory evaluation of the test vehicle's driving performance on dry roads was performed. The result was a score representing the driving performance, with a higher score indicating better dry performance.

[0087] <Performance on ice and snow>

[0088] The test vehicles' driving performance on icy and snowy roads was evaluated by the driver's sensory perception. The results were scored to indicate the driving performance, with higher values indicating better performance on icy and snowy roads.

[0089] The test results are shown in Table 1.

[0090] Table 1

[0091] Comparative Example Example Diagram showing tread pattern Figure 9 Figure 1 Dry performance (rating) 6.0 5.8 Performance on ice and snow (scoring) 6.0 7.0

[0092] As shown in Table 1, the comparative example tire's dry performance and performance on ice and snow were 6.0 points. In contrast, the tire of the example achieved dry performance of 5.8 points, a decrease of only 0.2 points compared to the comparative example. Meanwhile, the tire of the example achieved performance on ice and snow of 7.0 points, an improvement of 1.0 points compared to the comparative example. As can be seen from the above, the tire of the example maintains dry performance while also exhibiting excellent performance on ice and snow.

[0093] [Note]

[0094] The present invention includes the following aspects.

[0095] [Present invention 1]

[0096] 19. The tire of claim 18, wherein the plurality of grooves are configured to extend along the first and second tread edges of the tire and are configured to extend along the first and second tread edges of the tire. The first inclined groove is connected to any one of the plurality of second inclined grooves and forms a terminal, the plurality of second inclined grooves are connected to any one of the plurality of first inclined grooves and form a terminal, the plurality of pattern blocks include: a plurality of crown pattern blocks, which are arranged on the tire equator; a plurality of first shoulder pattern blocks, which include the first tread end and are divided by the two first inclined grooves and the first shoulder longitudinal groove; and a plurality of first intermediate pattern blocks, which are arranged between the plurality of crown pattern blocks and the plurality of first shoulder pattern blocks, a plurality of sipes are respectively formed on the tread of the first shoulder pattern block, the tread of the first intermediate pattern block, and the tread of the crown pattern block, and for each pattern block, the total length (mm) of the plurality of sipes formed on the tread is divided by the area (mm) of the tread. 2 ) and the obtained value is set as the tool groove density (mm / mm 2 ), the sipe density SDc of the crown block, the sipe density SDm of the first middle block, and the sipe density SDs of the first shoulder block satisfy: SDc>SDs, and SDm>SDs.

[0097] [Present invention 2]

[0098] In the tire according to the first aspect of the present invention, the sipe density SDs is 0.10 to 0.15 mm / mm. 2 .

[0099] [Present invention 3]

[0100] In the tire according to the first or second aspect of the present invention, the sipe density SDc and the sipe density SDm are respectively 0.17 to 0.23 mm / mm. 2 .

[0101] [Present invention 4]

[0102] In the tire according to any one of Inventions 1 to 3, the sipe density SDc and the sipe density SDm are each 140% to 160% of the sipe density SDs.

[0103] [Present invention 5]

[0104] In the tire according to any one of Inventions 1 to 4, the sipe density SDc is 80% to 120% of the sipe density SDm.

[0105] [Present invention 6]

[0106] In the tire according to any one of Inventions 1 to 5, the tread width, which is the distance in the tire axial direction from the first tread end to the second tread end, is 75% to 85% of the nominal width of the tire.

[0107] [Present invention 7]

[0108] In the tire according to any one of Inventions 1 to 6, the plurality of sipes are each arranged at an angle of 15° or less with respect to the tire axial direction.

[0109] [Present invention 8]

[0110] In the tire described in any one of 1 to 7 of the present invention, the above-mentioned multiple pattern blocks include: multiple second intermediate pattern blocks, which are adjacent to the above-mentioned second tread end sides of the above-mentioned multiple crown pattern blocks via the above-mentioned grooves; and multiple second shoulder pattern blocks, which are adjacent to the above-mentioned second tread end sides of the above-mentioned multiple second intermediate pattern blocks via the above-mentioned grooves, and multiple groups of V-shaped pattern block groups are arranged on the above-mentioned tread portion along the circumferential direction of the tire, and the V-shaped pattern block groups respectively include one of the above-mentioned crown pattern blocks, one of the above-mentioned first intermediate pattern blocks, one of the above-mentioned second intermediate pattern blocks, one of the above-mentioned first shoulder pattern blocks and one of the above-mentioned second shoulder pattern blocks.

[0111] [Present invention 9]

[0112] In the tire described in any one of 1 to 8 of the present invention, the above-mentioned multiple first inclined grooves include main first inclined grooves and secondary first inclined grooves alternating in the tire circumferential direction, the above-mentioned main first inclined grooves terminate at a position closer to the above-mentioned second tread end side than the tire equator, and the above-mentioned secondary first inclined grooves terminate without crossing the tire equator.

[0113] [Present invention 10]

[0114] In the tire according to any one of Inventions 1 to 9, the groove width of the first shoulder longitudinal groove continuously increases toward the leading ground contact side in the rotational direction.

[0115] [Present invention 11]

[0116] In the tire according to any one of Inventions 1 to 10, the first shoulder block is provided with a single longitudinal narrow groove that communicates with the two first oblique grooves and extends with a constant groove width.

[0117] [Present invention 12]

[0118] In the tire according to any one of the eleventh aspect of the present invention, the narrow longitudinal groove is inclined toward the first tread end side as it moves toward the first contact side in the rotational direction.

[0119] [Present invention 13]

[0120] In the tire according to Invention 12, the plurality of sipes provided on the tread surface of the first shoulder block include a plurality of first shoulder sipes extending linearly from the longitudinal narrow groove at least to the first tread end.

[0121] [Present invention 14]

[0122] In the tire according to any one of Inventions 1 to 13, the first middle block is provided with one middle short groove that communicates with one first inclined groove and has a closed end in the tread.

[0123] [Present invention 15]

[0124] In the tire according to any one of Inventions 1 to 14, the tread portion includes a tread rubber constituting the tread surface, and the tread rubber has a rubber hardness of 50 to 65 degrees.

Claims

1. A tire having a tread portion with a designated rotational direction, characterized in that: The tread portion includes a first tread end and a second tread end, a plurality of grooves provided between the first tread end and the second tread end, and a plurality of blocks divided by the plurality of grooves. The plurality of trenches include: a plurality of first inclined grooves extending obliquely from at least the first tread end toward the tire equator toward the first ground contact side in the rotational direction; a plurality of second inclined grooves extending obliquely from at least the second tread end toward the tire equator toward the first ground contact side in the rotational direction; a plurality of first shoulder longitudinal grooves connected to two of the first inclined grooves adjacent to each other in the tire circumferential direction and extending in the tire circumferential direction; and A plurality of first crown longitudinal grooves are arranged between the plurality of first shoulder longitudinal grooves and the tire equator and communicate with the two first oblique grooves. The plurality of first inclined grooves are respectively connected to any one of the plurality of second inclined grooves to form a terminal. The plurality of second inclined grooves are respectively connected to any one of the plurality of first inclined grooves to form a terminal. The plurality of pattern blocks include: A plurality of crown tread blocks are arranged at the tire equator; a plurality of first shoulder blocks, including the first tread end and divided by the two first oblique grooves and the first shoulder longitudinal groove; and a plurality of first middle tread blocks disposed between the plurality of crown tread blocks and the plurality of first shoulder tread blocks; A plurality of sipes are formed on the tread surface of the first shoulder block, the tread surface of the first middle block, and the tread surface of the crown block, respectively. For each block, when the value obtained by dividing the total length of the plurality of sipes formed on the tread by the area of the tread is defined as the sipe density, The sipe density SDc of the crown block, the sipe density SDm of the first middle block, and the sipe density SDs of the first shoulder block satisfy: SDc>SDs, and SDm>SDs, The unit of the total length is mm, and the unit of the area is mm 2 The unit of the grooving density is mm / mm 2 .

2. The tire according to claim 1, wherein The sipe density SDs is 0.10 to 0.15 mm / mm 2 .

3. The tire according to claim 2, characterized in that The groove density SDc and the groove density SDm are respectively 0.17 to 0.23 mm / mm 2 .

4. The tire according to claim 3, characterized in that The sipe density SDc and the sipe density SDm are respectively 140% to 160% of the sipe density SDs.

5. The tire according to claim 4, characterized in that The sipe density SDc is 80% to 120% of the sipe density SDm.

6. The tire according to any one of claims 1 to 5, characterized in that The tread width, which is a distance from the first tread end to the second tread end in the tire axial direction, is 75% to 85% of the nominal width of the tire.

7. The tire according to any one of claims 1 to 5, characterized in that The plurality of sipes are each arranged at an angle of 15° or less with respect to the tire axial direction.

8. The tire according to any one of claims 1 to 5, characterized in that The plurality of blocks include: a plurality of second middle blocks adjacent to the second tread end sides of the plurality of crown blocks via the grooves; and a plurality of second shoulder blocks adjacent to the second tread end sides of the plurality of second middle blocks via the grooves. A plurality of V-shaped block groups are provided on the tread portion along the tire circumferential direction, and the V-shaped block groups respectively include one crown block, one first middle block, one second middle block, one first shoulder block and one second shoulder block.

9. The tire according to any one of claims 1 to 5, characterized in that The plurality of first inclined grooves include main first inclined grooves and auxiliary first inclined grooves that alternate in the tire circumferential direction. The main first inclined grooves terminate at positions closer to the second tread end than the tire equator, and the auxiliary first inclined grooves terminate without crossing the tire equator.

10. The tire according to any one of claims 1 to 5, characterized in that The groove width of the first shoulder longitudinal groove continuously increases toward the first land contact side in the rotational direction.

11. The tire according to any one of claims 1 to 5, characterized in that The first shoulder block is provided with a single longitudinal narrow groove that communicates with the two first oblique grooves and extends with a constant groove width.

12. The tire according to claim 11, characterized in that The longitudinal narrow groove is inclined toward the first tread end side as it goes toward the first ground contact side in the rotation direction.

13. The tire according to claim 12, characterized in that The plurality of sipes provided on the tread surface of the first shoulder block include a plurality of first shoulder sipes extending linearly from the longitudinal narrow groove to at least the first tread end.

14. The tire according to any one of claims 1 to 5, characterized in that The first middle block is provided with a middle short groove that communicates with the first inclined groove and has a closed end in the tread.

15. The tire according to any one of claims 1 to 5, characterized in that The tread portion includes tread rubber constituting the tread, The tread rubber has a hardness of 50 to 65 degrees.

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