Tire

Abstract

The present invention provides a tire that can balance wet road performance, snow performance, and noise performance. The tire (1) has a tread surface portion (2). A plurality of circumferential grooves (3) extending in the circumferential direction of the tire and a plurality of land portions (4) defined by the circumferential grooves (3) are formed in the tread surface portion. The circumferential grooves include: a first circumferential groove (3A) and a second circumferential groove (3B) adjacent to the first circumferential groove (3A) and having a groove width larger than that of the first circumferential groove (3A). The land portion (4) includes a first land portion (4A) defined between the first circumferential groove (3A) and the second circumferential groove (3B). A plurality of transverse grooves (5) extending in the axial direction of the tire and a plurality of transverse knife grooves (6) extending in the axial direction of the tire and having a groove width smaller than that of the transverse grooves (5) are provided in the first land portion (4A). The total value of the groove widths of the transverse grooves (5) and the transverse knife grooves (6) communicating with the second circumferential groove (3B) is smaller than the total value of the groove widths of the transverse grooves (5) and the transverse knife grooves (6) communicating with the first circumferential groove (3A).

Description

Technical Field

[0001] The present invention relates to a tire having a tread surface portion. Background Art

[0002] Conventionally, a tire having a tread surface portion is known, and the tread surface portion is formed with a plurality of circumferential grooves extending in the circumferential direction of the tire and a plurality of land portions divided by the circumferential grooves. For example, the tire of Patent Document 1 below proposes a so-called all-season tire, that is, an intermediate land portion divided by a central main groove and a shoulder main groove extending in the circumferential direction of the tire has a plurality of intermediate transverse grooves and intermediate slits, so that a tire capable of traveling all-weather is provided.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-114846

[0004] However, in the tire of Patent Document 1, by increasing the ratio of the grooves to improve the drainage performance and snow removal performance, thereby improving the wet road performance and snow performance, there is a tendency that the pattern noise caused by the air column resonance sound of the grooves becomes larger, and thus further improvement in noise performance is required. Summary of the Invention

[0005] The present invention has been made in view of the above actual situation, and a main object thereof is to provide a tire capable of achieving both wet road performance, snow performance, and noise performance.

[0006] The tire of the present invention has a tread surface portion, and is characterized in that, in the tread surface portion, there are formed: a plurality of circumferential grooves extending in the circumferential direction of the tire, and a plurality of land portions divided by the circumferential grooves, the circumferential grooves include: a first circumferential groove, and a second circumferential groove adjacent to the first circumferential groove and having a groove width larger than that of the first circumferential groove, the land portions include a first land portion divided between the first circumferential groove and the second circumferential groove, and in the first land portion, there are provided: a plurality of transverse grooves extending in the axial direction of the tire, and a plurality of transverse slits extending in the axial direction of the tire and having a groove width smaller than that of the transverse grooves, and the total value of the groove widths of the transverse grooves and the transverse slits communicating with the second circumferential groove is smaller than the total value of the groove widths of the transverse grooves and the transverse slits communicating with the first circumferential groove.

[0007] In the tire of the present invention, it is preferable that the number of the transverse grooves and the transverse slits communicating with the second circumferential groove is equal to the number of the transverse grooves and the transverse slits communicating with the first circumferential groove.

[0008] In the tire of the present invention, it is preferable that the transverse grooves include a first transverse groove extending from the first circumferential groove and having a terminal end formed within the first land portion, and a second transverse groove extending from the second circumferential groove and having a terminal end formed within the first land portion, and the axial lengths of the first transverse groove and the second transverse groove in the tire axial direction are respectively 20% to 35% of the axial width of the first land portion in the tire axial direction.

[0009] In the tire of the present invention, preferably, the transverse knife grooves include: thick transverse knife grooves having a groove width smaller than that of the transverse grooves, and thin transverse knife grooves having a groove width smaller than that of the thick transverse knife grooves. The thin transverse knife grooves include: a first thin transverse knife groove connecting the first transverse groove and the second circumferential groove, and a second thin transverse knife groove connecting the second transverse groove and the first circumferential groove.

[0010] In the tire of the present invention, preferably, the transverse knife grooves include: thick transverse knife grooves having a groove width smaller than that of the transverse grooves, and thin transverse knife grooves having a groove width smaller than that of the thick transverse knife grooves. The thick transverse knife grooves extend from the first circumferential groove and form terminals within the first land portion.

[0011] In the tire of the present invention, preferably, the axial length of the thick transverse knife grooves in the tire is 60% to 80% of the axial width of the first land portion.

[0012] In the tire of the present invention, preferably, the thin transverse knife grooves include a third thin transverse knife groove connecting the thick transverse knife grooves and the second circumferential groove.

[0013] In the tire of the present invention, preferably, the depth of the thick transverse knife grooves is 60% to 80% of the depth of the first circumferential groove.

[0014] In the tire of the present invention, preferably, a cutout portion recessed axially along the tire from the first circumferential groove is provided in the first land portion.

[0015] In the tire of the present invention, preferably, the first circumferential groove is a shoulder circumferential groove disposed on the outer side in the tire axial direction, and the second circumferential groove is a crown circumferential groove disposed on the inner side in the tire axial direction of the shoulder circumferential groove.

[0016] In the tire of the present invention, the circumferential grooves include: a first circumferential groove, and a second circumferential groove adjacent to the first circumferential groove and having a groove width larger than that of the first circumferential groove. The land portions include a first land portion divided between the first circumferential groove and the second circumferential groove. In the first land portion, there are provided: a plurality of transverse grooves extending axially along the tire, and a plurality of transverse knife grooves extending axially along the tire and having a groove width smaller than that of the transverse grooves. Such a tire can improve the drainage performance, snow removal performance, and edge effect through the transverse grooves and transverse knife grooves, thereby improving the wet road performance and snow performance.

[0017] In the tire of the present invention, the total width of the transverse grooves and the transverse knife grooves communicating with the second circumferential groove is smaller than the total width of the transverse grooves and the transverse knife grooves communicating with the first circumferential groove. For such a tire, the total width of the transverse grooves and the transverse knife grooves communicating with the second circumferential groove having a larger groove width is smaller, so that column resonance sound can be suppressed and the noise performance can be improved. Therefore, the tire of the present invention can balance wet road performance, snow performance, and noise performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. is a developed view showing an embodiment of the tread surface of the tire of the present invention.

[0019] Figure 2 FIG. is an enlarged view showing the first land portion.

[0020] Figure 3 is Figure 1 a cross-sectional view taken along line A-A of

[0021] Reference numerals: 1... tire; 2... tread surface; 3... circumferential groove; 3A... first circumferential groove; 3B... second circumferential groove; 4... land portion; 4A... first land portion; 5... transverse groove; 6... transverse knife groove DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

[0023] Figure 1 FIG. is a developed view showing the tread surface 2 of the tire 1 of the present embodiment. As Figure 1 shown, the tire 1 of the present embodiment has a tread surface 2 that contacts the ground during driving.

[0024] The tire 1 is suitable for use, for example, as a pneumatic tire that can be driven all-weather and is mounted on a passenger car or an SUV. Here, the tire 1 that can be driven all-weather is a tire 1 that requires handling stability on a dry road surface (hereinafter referred to as "dry road performance"), braking performance on a wet road surface (hereinafter referred to as "wet road performance"), handling stability on a snow road surface (hereinafter referred to as "snow performance"), etc. The tire 1 is not limited to such a mode, and can be used, for example, for various tires 1 such as pneumatic tires for heavy loads and non-pneumatic tires that do not fill pressurized air inside.

[0025] In the tread surface 2 of the present embodiment, a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of land portions 4 divided by the circumferential grooves 3 are formed. The circumferential grooves 3 include, for example, a first circumferential groove 3A and a second circumferential groove 3B that is adjacent to the first circumferential groove 3A and has a larger groove width than the first circumferential groove 3A. The land portion 4 of the present embodiment includes a first land portion 4A divided between the first circumferential groove 3A and the second circumferential groove 3B.

[0026] Figure 2 is an enlarged view showing the first land portion 4A. As Figure 2 shown, it is preferable that the first land portion 4A is provided with: a plurality of transverse grooves 5 extending in the tire axial direction, and a plurality of transverse knife grooves 6 extending in the tire axial direction and having a groove width smaller than that of the transverse grooves 5. Such a tire 1 can improve the drainage performance, snow removal performance, and edge effect through the transverse grooves 5 and the transverse knife grooves 6, and can improve the wet road performance and snow performance.

[0027] Here, in this specification, a knife groove is defined as a thin cut groove having a groove width of 2.0 mm or less. On the other hand, a groove is defined as a groove having a groove width greater than 2.0 mm. In addition, the groove width is the width on the outer surface of the tire in a direction orthogonal to the length direction of the groove and the knife groove, and is the maximum value of the width except for portions where the local size changes such as the cutout portion 9a and the chamfered portion 9b described later.

[0028] In addition, in this specification, unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in a normal state. Here, the "normal state" means that when the tire 1 is a pneumatic tire, the tire 1 rim is assembled to a normal rim and adjusted to a non-loaded state with a normal internal pressure.

[0029] The "normal rim" is a rim specified for each tire in the case where there is a specification system including the specifications on which the tire 1 is based. For example, if it is JATMA, it is the "standard rim"; if it is TRA, it is the "DesignRim"; if it is ETRTO, it is the "Measuring Rim". The "normal rim" is a rim specified by a manufacturer or the like for each tire in the case where there is no specification system including the specifications on which the tire 1 is based.

[0030] The "normal internal pressure" is the air pressure specified for each specification for each tire in the case where there is a specification system including the specifications on which the tire 1 is based. If it is JATMA, it is the "maximum air pressure"; if it is TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; if it is ETRTO, it is the "INFLATION PRESSURE". The "normal internal pressure" is the air pressure specified by a manufacturer or the like for each tire in the case where there is no specification system including the specifications on which the tire 1 is based.

[0031] The total width of the transverse grooves 5 and transverse knife grooves 6 communicating with the second circumferential groove 3B of the present embodiment is smaller than the total width of the transverse grooves 5 and transverse knife grooves 6 communicating with the first circumferential groove 3A. For such a tire 1, since the total width of the transverse grooves 5 and transverse knife grooves 6 communicating with the second circumferential groove 3B having a larger groove width is smaller, column resonance sound can be suppressed and the noise performance can be improved. Therefore, the tire 1 of the present embodiment can achieve both wet road performance, snow performance, and noise performance.

[0032] As a more preferable embodiment, the groove width W2 of the second circumferential groove 3B is 105% to 120% of the groove width W1 of the first circumferential groove 3A. By making the groove width W2 of the second circumferential groove 3B be 105% or more of the groove width W1 of the first circumferential groove 3A, the drainage performance of draining water using the second circumferential groove 3B can be improved, and the wet road performance of the tire 1 can be further improved. From this perspective, the groove width W2 of the second circumferential groove 3B is more preferably 108% or more of the groove width W1 of the first circumferential groove 3A, and further preferably 110% or more.

[0033] By making the groove width W2 of the second circumferential groove 3B be 120% or less of the groove width W1 of the first circumferential groove 3A, a reduction in the rigidity of the first land portion 4A can be suppressed, and the dry road performance and wear resistance of the tire 1 can be improved. From this perspective, the groove width W2 of the second circumferential groove 3B is more preferably 117% or less of the groove width W1 of the first circumferential groove 3A, and further preferably 115% or less.

[0034] In the present embodiment, the number of the transverse grooves 5 and transverse knife grooves 6 communicating with the second circumferential groove 3B is equal to the number of the transverse grooves 5 and transverse knife grooves 6 communicating with the first circumferential groove 3A. Therefore, in the present embodiment, the difference in the total width of the transverse grooves 5 and transverse knife grooves 6 communicating with the first circumferential groove 3A and the second circumferential groove 3B is based on the difference in the respective groove widths of the transverse grooves 5 and transverse knife grooves 6 communicating with the first circumferential groove 3A and the second circumferential groove 3B.

[0035] The transverse groove 5 includes, for example, a first transverse groove 5A extending from the first circumferential groove 3A and forming a terminal within the first land portion 4A, and a second transverse groove 5B extending from the second circumferential groove 3B and forming a terminal within the first land portion 4A. Such a transverse groove 5 can prevent the rigidity of the first land portion 4A from decreasing, and improve the wet road performance and snow performance of the tire 1.

[0036] The axial length L1 of the first transverse groove 5A is preferably 20% to 35% of the axial width W3 of the first land portion 4A. By making the length L1 of the first transverse groove 5A 20% or more of the width W3 of the first land portion 4A, drainage performance and snow column shearing force can be improved, and the wet road performance and snow performance of the tire 1 can be enhanced. From this perspective, the length L1 of the first transverse groove 5A is more preferably 23% or more of the width W3 of the first land portion 4A, and further preferably 25% or more.

[0037] By making the length L1 of the first transverse groove 5A 35% or less of the width W3 of the first land portion 4A, the rigidity of the first land portion 4A can be maintained, and the dry road performance and wear resistance of the tire 1 can be improved. From this perspective, the length L1 of the first transverse groove 5A is more preferably 32% or less of the width W3 of the first land portion 4A, and further preferably 30% or less.

[0038] The axial length L2 of the second transverse groove 5B is preferably 20% to 35% of the axial width W3 of the first land portion 4A. By making the length L2 of the second transverse groove 5B 20% or more of the width W3 of the first land portion 4A, drainage performance and snow column shearing force can be improved, and the wet road performance and snow performance of the tire 1 can be enhanced. From this perspective, the length L2 of the second transverse groove 5B is more preferably 23% or more of the width W3 of the first land portion 4A, and further preferably 25% or more.

[0039] By making the length L2 of the second transverse groove 5B 35% or less of the width W3 of the first land portion 4A, the rigidity of the first land portion 4A can be maintained, and the dry road performance and wear resistance of the tire 1 can be improved. From this perspective, the length L2 of the second transverse groove 5B is more preferably 32% or less of the width W3 of the first land portion 4A, and further preferably 30% or less.

[0040] The length L2 of the second transverse groove 5B in this embodiment is less than the length L1 of the first transverse groove 5A. Such a second transverse groove 5B can suppress a reduction in the rigidity of the first land portion 4A on the side of the second circumferential groove 3B with a relatively large groove width W2, and improve the dry road performance and wear resistance of the tire 1.

[0041] The groove width W4 of the first transverse groove 5A is preferably 30% to 40% of the groove width W1 of the first circumferential groove 3A. The groove width W5 of the second transverse groove 5B is preferably 25% to 35% of the groove width W2 of the second circumferential groove 3B. The groove width W5 of the second transverse groove 5B in this embodiment is equal to the groove width W4 of the first transverse groove 5A. Such transverse grooves 5 are suitable for balancing the snow performance and noise performance of the tire 1.

[0042] Figure 3 Yes Figure 1Cross-sectional view taken along line A-A. As Figure 3 shown, the depth d1 of the first transverse groove 5A is preferably 60% to 80% of the depth D1 of the first circumferential groove 3A. The depth of the second transverse groove 5B in the present embodiment is equal to the depth d1 of the first transverse groove 5A. Such a transverse groove 5 is suitable for balancing snow performance and noise performance.

[0043] As Figure 2 shown, the transverse knife groove 6 in the present embodiment includes: a thick transverse knife groove 7 with a groove width smaller than that of the transverse groove 5, and a thin transverse knife groove 8 with a groove width smaller than that of the thick transverse knife groove 7. Such a transverse knife groove 6 can balance the improvement of the snow performance of the tire 1 brought about by the edge effect and the improvement of the noise performance brought about by the smaller groove width.

[0044] The thick transverse knife groove 7 of the present embodiment extends from the first circumferential groove 3A and forms a terminal within the first land portion 4A. The thick transverse knife groove 7 includes a plurality of bending portions, which are two bending portions in the present embodiment. The groove width W6 of the thick transverse knife groove 7 is preferably 1.2 to 1.5 mm. Such a thick transverse knife groove 7 can improve the wet road performance and snow performance of the tire 1.

[0045] The axial length L3 of the thick transverse knife groove 7 in the tire axial direction is preferably 60% to 80% of the axial width W3 of the first land portion 4A in the tire axial direction. By making the length L3 of the thick transverse knife groove 7 60% or more of the width W3 of the first land portion 4A, good drainage performance and edge effect can be maintained, and the wet road performance and snow performance of the tire 1 can be improved. From this point of view, the length L3 of the thick transverse knife groove 7 is more preferably 63% or more of the width W3 of the first land portion 4A, and further preferably 65% or more.

[0046] By making the length L3 of the thick transverse knife groove 7 80% or less of the width W3 of the first land portion 4A, the rigidity of the first land portion 4A can be maintained, and the dry road performance and wear resistance of the tire 1 can be improved. From this point of view, the length L3 of the thick transverse knife groove 7 is more preferably 77% or less of the width W3 of the first land portion 4A, and further preferably 75% or less.

[0047] As Figure 3 shown, the depth d2 of the thick transverse knife groove 7 is preferably 60% to 80% of the depth D1 of the first circumferential groove 3A. By making the depth d2 of the thick transverse knife groove 7 60% or more of the depth D1 of the first circumferential groove 3A, the drainage performance can be improved, and the wet road performance of the tire 1 can be improved. From this point of view, the depth d2 of the thick transverse knife groove 7 is more preferably 63% or more of the depth D1 of the first circumferential groove 3A, and further preferably 65% or more.

[0048] By making the depth d2 of the thick transverse groove 7 be 80% or less of the depth D1 of the first circumferential groove 3A, the rigidity of the first land portion 4A can be maintained, and the dry road performance and wear resistance of the tire 1 can be improved. From this perspective, the depth d2 of the thick transverse groove 7 is more preferably 77% or less of the depth D1 of the first circumferential groove 3A, and even more preferably 75% or less.

[0049] The thin transverse grooves 8 include, for example, a first thin transverse groove 8A that connects the first transverse groove 5A and the second circumferential groove 3B, and a second thin transverse groove 8B that connects the second transverse groove 5B and the first circumferential groove 3A. The groove width W8 of the second thin transverse groove 8B is preferably equal to the groove width W7 of the first thin transverse groove 8A. The groove width W7 of the first thin transverse groove 8A and the groove width W8 of the second thin transverse groove 8B are preferably 1.0 mm or less.

[0050] The thin transverse grooves 8 also preferably include a third thin transverse groove 8C that connects the thick transverse groove 7 and the second circumferential groove 3B. The groove width W9 of the third thin transverse groove 8C is, for example, smaller than the groove width W7 of the first thin transverse groove 8A.

[0051] In the first land portion 4A of the present embodiment, a cutout portion 9a that recesses axially of the tire from the first circumferential groove 3A is provided. The cutout portion 9a is provided, for example, throughout the area between the first transverse groove 5A and the thick transverse groove 7. Such a cutout portion 9a can assist the drainage performance of the first circumferential groove 3A and increase the snow column shearing force, thereby improving the wet road performance and snow performance of the tire 1. In addition, since the cutout portion 9a is provided locally along the length direction of the first circumferential groove 3A, the influence on the noise performance of the tire 1 can be reduced.

[0052] In the first land portion 4A of the present embodiment and at the connecting portion of the transverse groove 5 and the circumferential groove 3, a chamfered portion 9b is provided. The chamfered portion 9b is provided, for example, at the acute-angle corner portion of the transverse groove 5 and the circumferential groove 3. Such a chamfered portion 9b can suppress stress concentration at the corner portion and suppress local defects and uneven wear of the first land portion 4A.

[0053] As Figure 1 shown, the land portion 4 includes, for example, a second land portion 4B that is divided on the opposite side of the first land portion 4A with the first circumferential groove 3A interposed therebetween, and a third land portion 4C that is divided on the opposite side of the first land portion 4A with the second circumferential groove 3B interposed therebetween. The third land portion 4C of the present embodiment is divided between a pair of second circumferential grooves 3B. In addition, when there is one second circumferential groove 3B, the third land portion 4C is omitted.

[0054] In the second land portion 4B, for example, a third transverse groove 10 extending in the tire axial direction, a fourth fine transverse groove 11A, and a fifth fine transverse groove 11B are provided. At least the end portion on the first circumferential groove 3A side of the third transverse groove 10 forms a terminal within the second land portion 4B. Such a third transverse groove 10 can prevent the rigidity of the second land portion 4B from decreasing and improve the wet road performance and snow performance of the tire 1. In addition, since the third transverse groove 10 does not communicate with the first circumferential groove 3A, the noise performance of the tire 1 can be improved.

[0055] The fourth fine transverse groove 11A preferably communicates the third transverse groove 10 with the first circumferential groove 3A. The fifth fine transverse groove 11B, for example, extends at least partially in a serrated shape starting from the first circumferential groove 3A. Such a fourth fine transverse groove 11A and a fifth fine transverse groove 11B can take into account both the improvement of the snow performance of the tire 1 brought about by the edge effect and the improvement of the noise performance brought about by the smaller groove width.

[0056] In the second land portion 4B of the present embodiment, a longitudinal groove 12 extending in the tire circumferential direction is provided. The longitudinal groove 12, for example, extends in a manner intersecting with the third transverse groove 10 and the fifth fine transverse groove 11B. Such a longitudinal groove 12 can prevent the rigidity of the second land portion 4B from decreasing and improve the snow performance of the tire 1.

[0057] In the third land portion 4C, for example, a fourth transverse groove 13 extending in the tire axial direction and a second thick transverse groove 14 are provided. The fourth transverse groove 13 preferably extends from the second circumferential groove 3B and forms a terminal within the third land portion 4C. The fourth transverse groove 13 of the present embodiment extends from both sides in the tire axial direction toward the inside of the third land portion 4C. Such a fourth transverse groove 13 can prevent the rigidity of the third land portion 4C from decreasing and improve the wet road performance and snow performance of the tire 1.

[0058] As Figure 3 shown, it is preferable that the depth d3 of the fourth transverse groove 13 is shallower than the depth D2 of the second circumferential groove 3B. Such a fourth transverse groove 13 is suitable for taking into account both snow performance and noise performance.

[0059] As Figure 1 shown, the second thick transverse groove 14, for example, crosses the third land portion 4C. The second thick transverse groove 14 of the present embodiment communicates with the pair of second circumferential grooves 3B respectively. Such a second thick transverse groove 14 can improve the wet road performance and snow performance of the tire 1.

[0060] In the third land portion 4C of the present embodiment, a second cutout portion 15 is provided that recesses axially of the tire from the second circumferential groove 3B. The second cutout portion 15 is provided at least at a position including the fourth transverse groove 13. Such a second cutout portion 15 assists the drainage performance of the second circumferential groove 3B and increases the snow column shearing force, thereby improving the wet road performance and snow performance of the tire 1. In addition, since the second cutout portion 15 is provided locally along the longitudinal direction of the second circumferential groove 3B, the influence on the noise performance of the tire 1 can be reduced.

[0061] In the present embodiment, the first circumferential groove 3A is a shoulder circumferential groove disposed on the outer side in the tire axial direction. In addition, the second circumferential groove 3B of the present embodiment is a crown circumferential groove disposed on the inner side in the tire axial direction of the shoulder circumferential groove. For such a tire 1, the groove width of the crown circumferential groove on the inner side in the tire axial direction where the contact pressure is large is large, so that the drainage performance can be improved and the wet road performance can be improved. In addition, for this tire 1, the groove width of the shoulder circumferential groove on the outer side in the tire axial direction is small, so that the noise transmitted to the outside can be reduced, and thus the noise performance can be improved.

[0062] The first land portion 4A of the present embodiment is an intermediate land portion. In addition, the second land portion 4B of the present embodiment is a shoulder land portion. Furthermore, the third land portion 4C of the present embodiment is a crown land portion. Such a tire 1 can balance the wet road performance, snow performance, and noise performance by means of the transverse grooves 5 and transverse knife grooves 6 provided in the intermediate land portion.

[0063] As described above, the particularly preferred embodiments of the present invention have been described in detail, but the present invention is not limited to the above-described embodiments and can be implemented in various modified forms.

[0064]

Example

[0065] A tire having a Figure 1 tread pattern was trial-produced according to the specifications in Table 1. As a comparative example, a tire in which the transverse groove crosses the first land portion and no thick transverse knife groove is provided was trial-produced. Using these trial-produced tires, the dry road performance, wet road performance, snow performance, noise performance, and abrasion resistance were tested. The main common specifications and test methods are as follows.

[0066] <Common specifications>

[0067] Tire size: 255 / 50R20 105H

[0068] Rim size: 20×8.0J

[0069] Air pressure: 240 kPa

[0070] Test vehicle: Medium-sized four-wheel drive vehicle

[0071] Tire mounting position: All wheels

[0072] <Dry Road Performance>

[0073] The handling stability of a test vehicle equipped with the prototype tires was evaluated by the driver's senses while driving on a paved road in a dry road condition. The results are expressed as an index with the comparative example being 100. The larger the value, the better the sensory evaluation and the more excellent the dry road performance.

[0074] <Wet Road Performance>

[0075] Using a test vehicle equipped with the prototype tires, the braking distance was measured when braking from an initial speed of 100 km / h on a paved road with a 1-mm water film. The results are expressed as an index with the comparative example being 100. The larger the value, the smaller the braking distance and the more excellent the wet road performance.

[0076] <Snow Performance>

[0077] The handling stability of a test vehicle equipped with the prototype tires was evaluated by the driver's senses while driving on a snow road. The results are expressed as an index with the comparative example being 100. The larger the value, the better the sensory evaluation and the more excellent the snow performance.

[0078] <Noise Performance>

[0079] The passing noise level of a test vehicle equipped with the prototype tires was measured while driving at a speed of 50 km / h on a noise measurement road. The results are expressed as an index with the comparative example being 100. The larger the value, the smaller the passing noise level and the more excellent the noise performance.

[0080] <Abrasion Resistance Performance>

[0081] The remaining groove amount was measured when a test vehicle equipped with the prototype tires was driven on a paved road in a dry road condition at an average speed of 80 km / h for 96 hours. The results are expressed as an index with the comparative example being 100. The larger the value, the larger the remaining groove amount and the more excellent the abrasion resistance performance.

[0082] The test results are shown in Table 1.

[0083]

Table 1

[0084]

[0085] The test results confirmed that: compared with the comparative example, the tires of the example have good balanced performance evaluated by the sum of various performances, and in particular, can balance wet road performance, snow performance, and noise performance.

Claims

1. A tire having a tread surface, characterized in that, formed on the tread surface are: a plurality of circumferential grooves extending along the circumferential direction of the tire, and a plurality of land portions divided by the circumferential grooves, the circumferential grooves include: a first circumferential groove, and a second circumferential groove adjacent to the first circumferential groove and having a groove width larger than that of the first circumferential groove, the land portions include a first land portion divided between the first circumferential groove and the second circumferential groove, provided on the first land portion are: a plurality of transverse grooves extending along the axial direction of the tire, and a plurality of transverse knife grooves extending along the axial direction of the tire and having a groove width smaller than that of the transverse grooves, the total value of the groove widths of the transverse grooves and the transverse knife grooves communicating with the second circumferential groove is smaller than the total value of the groove widths of the transverse grooves and the transverse knife grooves communicating with the first circumferential groove, the transverse knife grooves include: thick transverse knife grooves having a groove width smaller than that of the transverse grooves, and thin transverse knife grooves having a groove width smaller than that of the thick transverse knife grooves, the thick transverse knife grooves extend from the first circumferential groove and form terminals within the first land portion, the thin transverse knife grooves include third thin transverse knife grooves connecting the thick transverse knife grooves and the second circumferential groove.

2. The tire according to claim 1, characterized in that, the number of the transverse grooves and the transverse knife grooves communicating with the second circumferential groove is equal to the number of the transverse grooves and the transverse knife grooves communicating with the first circumferential groove.

3. The tire according to claim 1 or 2, characterized in that, the transverse grooves include a first transverse groove extending from the first circumferential groove and forming a terminal within the first land portion, and a second transverse groove extending from the second circumferential groove and forming a terminal within the first land portion, the axial lengths of the first transverse groove and the second transverse groove in the axial direction of the tire are respectively 20% - 35% of the axial width of the first land portion in the axial direction of the tire.

4. The tire according to claim 3, characterized in that, the thin transverse knife grooves include: a first thin transverse knife groove connecting the first transverse groove and the second circumferential groove, and a second thin transverse knife groove connecting the second transverse groove and the first circumferential groove.

5. The tire according to any one of claims 1, 2, and 4, characterized in that, the axial length of the thick transverse knife groove in the axial direction of the tire is 60% - 80% of the axial width of the first land portion in the axial direction of the tire.

6. The tire according to any one of claims 1, 2, and 4, characterized in that, the depth of the thick transverse knife groove is 60% - 80% of the depth of the first circumferential groove.

7. The tire according to any one of claims 1, 2, and 4, characterized in that, a cutout portion recessed axially from the first circumferential groove is provided in the first land portion.

8. The tire according to any one of claims 1, 2, and 4, characterized in that, the first circumferential groove is a shoulder circumferential groove disposed on the outer side in the axial direction of the tire, the second circumferential groove is a crown circumferential groove disposed on the inner side in the axial direction of the tire of the shoulder circumferential groove.

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