Tire

Abstract

A tire (1) is formed with a plurality of grooves (3) in a tread portion (2). The ground contact surface (2a) of the tread portion (2) when the camber angle is 0° and a standard load is applied in a standard state has a length in the tire circumferential direction, i.e., a ground contact length (L), associated with each position in the tire axial direction, and a distance from the tire equator (C) to the outer end in the tire axial direction of the ground contact surface (2a), i.e., a ground contact end (Te), i.e., a half ground contact width (Tw). The ground contact length (L) includes a crown ground contact length (LC) at the tire equator (C) and a shoulder ground contact length (LS) at a position spaced apart from the tire equator (C) by a distance of 80% of the half ground contact width (Tw). The crown ground contact length (LC) is 0.95 to 1.05 times the shoulder ground contact length (LS). When a reference imaginary groove (G0) set at a predetermined groove depth (d0) at the tire equator (C) is defined, the groove depths (d) of the plurality of grooves (3) each satisfy a prescribed formula.

Description

Technical Field

[0001] This invention relates to tires having a tread pattern. Background Technology

[0002] Previously, tires with a tread portion having multiple circumferential grooves extending in the circumferential direction of the tire were known. For example, Patent Document 1 below proposes a tire that improves wear resistance by defining the profile of the tread portion having multiple main grooves extending in the circumferential direction of the tire.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-182339

[0004] However, since the tire in Patent Document 1 has the same depth of main grooves, and the tread rigidity is reduced due to the large depth of the main grooves, further improvement in handling stability is expected. Summary of the Invention

[0005] The present invention was made in view of the above-mentioned actual situation, and its main objective is to provide a tire that can maintain excellent wear resistance and improve handling stability.

[0006] The present invention relates to a tire with a tread portion, characterized in that a plurality of grooves are formed in the tread portion, wherein, under standard conditions when the rim is assembled on a regular rim and adjusted to a standard internal pressure, the contact surface of the tread portion, with a camber angle of 0° and a standard load applied, has: a tire circumferential length, i.e., a contact length, related to various positions along the tire axial direction, and a distance from the tire equator to the outer end of the tire axial direction of the contact surface, i.e., the contact end, i.e., half the contact width, wherein the contact length includes: a crown contact length at the tire equator and a shoulder contact length at a position 80% of the half contact width away from the tire equator, wherein the crown contact length is 0.95 to 1.05 times the shoulder contact length, and when a reference imaginary groove is defined at the tire equator with a predetermined groove depth, the groove depth d of each of the plurality of grooves satisfies the following formula (1).

[0007]

[0008] in:

[0009] d0: Depth of the baseline hypothetical trench

[0010] LC: Length of tire crown to ground

[0011] L: Grounding length at the location of the trench

[0012] α: Correction factor.

[0013] Preferably, in the tire of the present invention, the groove includes a plurality of circumferential grooves extending along the tire circumference. When the following are defined in the tire radial profile under the standard unloaded state: the reference imaginary groove, the first imaginary groove set at a first position spaced from the tire equator along the tire axial direction, the second imaginary groove set at a second position further outward of the tire axial direction than the first position, the third imaginary groove set at a third position further outward of the tire axial direction than the second position, and an imaginary line tangent to the bottom of the reference imaginary groove, the bottom of the first imaginary groove, the bottom of the second imaginary groove, and the bottom of the third imaginary groove, the groove depth of the circumferential groove is within ±10% of the distance from the outer surface of the tread portion at the position where the circumferential groove is formed to the imaginary line. The groove depths d1 of the first imaginary groove, d2 of the second imaginary groove, and d3 of the third imaginary groove are defined based on the following formulas (2) to (4).

[0014]

[0015]

[0016]

[0017] in,

[0018] d0: Depth of the baseline hypothetical trench

[0019] LC: Length of tire crown to ground

[0020] L1: First grounding length

[0021] L2: Second grounding length

[0022] L3: Third grounding length

[0023] α: Correction factor.

[0024] Preferably, in the tire of the present invention, the first position is a position at a distance of 40% to 55% of half the ground contact width from the tire equator, the second position is a position at a distance of 75% to 80% of half the ground contact width from the tire equator, and the third position is a position at a distance of 90% to 85% of half the ground contact width from the tire equator.

[0025] Preferably, in the tire of the present invention, the correction factor is a positive number of 2.0 or less.

[0026] Preferably, in the tire of the present invention, the correction factor is 0.8 to 1.2.

[0027] Preferably, in the tire of the present invention, the circumferential groove includes: a first circumferential groove on the inner side of the tire axially and a second circumferential groove on the outer side of the tire axially, wherein the depth of the second circumferential groove is greater than the depth of the first circumferential groove.

[0028] Preferably, in the tire of the present invention, the groove includes a plurality of transverse grooves extending along the tire axial direction.

[0029] In the tire of the present invention, the contact patch length includes: a crown contact patch length at the tire equator and a shoulder contact patch length at a position 80% of the distance from the tire equator equal to half the contact patch width, wherein the crown contact patch length is 0.95 to 1.05 times the shoulder contact patch length. This results in a large tire contact patch area, which improves lateral stiffness and thus enhances handling stability.

[0030] In the tire of the present invention, when a reference imaginary groove with a predetermined groove depth centered on the tire equator is defined, the groove depth d of each of the plurality of grooves satisfies the above formula (1). Such grooves can suppress the situation where the groove depth increases excessively relative to the wear amount that varies with the tire's axial position, thereby improving the rigidity of the tread and thus improving the lateral stiffness. Therefore, the tire of the present invention can maintain excellent wear resistance and improve handling stability. Attached Figure Description

[0031] Figure 1 This is a cross-sectional schematic diagram showing one embodiment of the tire tread section of the present invention.

[0032] Figure 2 This is a schematic diagram showing the contact surface of the tire tread.

[0033] Figure 3 This is a cross-sectional schematic diagram showing the tread area of ​​another embodiment.

[0034] Figure 4 This is a flowchart illustrating one embodiment of the trench depth setting method of the present invention.

[0035] Explanation of reference numerals in the attached diagram: 1... tire; 2... tread; 2a... ground contact area; 3... groove. Detailed Implementation

[0036] Hereinafter, one embodiment of the present invention will be described in detail based on the accompanying drawings.

[0037] Figure 1This is a schematic cross-sectional view of the tire radial section of the tread portion 2 of the tire 1 in its standard state according to this embodiment. The tire 1 of this embodiment is suitable for use as a pneumatic tire for passenger cars. The tire 1 is not limited to a pneumatic tire for passenger cars; for example, it can also be used for various types of tires such as pneumatic tires for heavy loads, pneumatic tires for motorcycles, and non-air tires whose interior is not filled with pressurized air.

[0038] Here, "standard condition" refers to the unloaded state where tire 1 is a pneumatic tire, the tire 1 rim is assembled on a standard rim, and the tire is adjusted to the standard internal pressure. Furthermore, in this specification, unless otherwise specified, the dimensions of tire 1 are values ​​measured under the standard condition.

[0039] "Standard rim" refers to a rim with a specified specification for each tire, provided that a specification system exists that includes the specifications on which tire 1 is based. For example, if it is JATMA, it is a "standard rim"; if it is TRA, it is a "design rim"; and if it is ETRTO, it is a "measuring rim". If a specification system does not exist that includes the specifications on which tire 1 is based, a "standard rim" is a rim specified by the manufacturer or other entities for each tire.

[0040] "Standard internal pressure" refers to the air pressure specified for each tire in a specification system that includes the specifications upon which tire 1 is based. If it is JATMA, it is the "maximum air pressure"; if it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITSAT VARIOUS COLD INFLATION PRESSURES"; if it is ETRTO, it is the "INFLATION PRESSURE". In the absence of a specification system that includes the specifications upon which tire 1 is based, "standard internal pressure" is the air pressure specified by the manufacturer, etc., for each tire.

[0041] like Figure 1 As shown, the tire 1 of this embodiment has a tread portion 2 that contacts the road surface during driving. The tread portion 2 of this embodiment has a plurality of grooves 3. The grooves 3 include: a plurality of circumferential grooves 4 extending along the tire circumference (four in this embodiment), and a plurality of lateral grooves 5 extending along the tire axial direction.

[0042] The circumferential groove 4 includes, for example, a crown circumferential groove 4A located on the equator C side of the tire, and a shoulder circumferential groove 4B located on the axial outer side of the crown circumferential groove 4A. Such a tire 1, by means of multiple grooves 3, provides good drainage when driving on wet roads.

[0043] Figure 2 This is a schematic diagram showing the contact surface 2a of the tread area 2. For example... Figure 2As shown, in this embodiment, the tread portion 2, under standard conditions with a camber angle of 0° and a standard load applied, has a tire circumferential length, i.e., a contact length L, related to each position P along the tire axial direction. The contact portion 2a in this embodiment has a distance from the tire equator C to the outer end of the contact portion 2a along the tire axial direction, i.e., the contact end Te, which is half the contact width Tw. Furthermore, the tire equator C is the center position of the contact ends Te on both sides of the tire axial direction.

[0044] Here, "standard load" refers to the load specified for each tire in a specification system that includes the specifications upon which tire 1 is based. If JATMA is used, it is the "maximum load capacity"; if TRA is used, it is the maximum value recorded in the table "TIRE LOADLIMITS AT VARIOUS COLD INFLATION PRESSURES"; and if ETRTO is used, it is the "LOADCAPACITY". If a specification system that includes the specifications upon which tire 1 is based does not exist, "standard load" is the load specified by the manufacturer, etc., for each tire.

[0045] The contact patch length L includes, for example, the crown contact patch length LC at the tire equator C, and the shoulder contact patch length LS at a position P1 located at a distance W1 equal to 80% of half the contact patch width Tw from the tire equator C. In this embodiment, the crown contact patch length LC is 0.95 to 1.05 times the shoulder contact patch length LS. Such a tire 1, due to its large contact patch area, can improve lateral stiffness, thus enhancing handling stability.

[0046] like Figure 1 as well as Figure 2 As shown, when a reference imaginary groove G0 is defined at the tire equator C with a predetermined groove depth d0, the groove depth d of each of the plurality of grooves 3 in this embodiment satisfies the following formula (1).

[0047]

[0048] in,

[0049] d0: Depth of the baseline hypothetical trench

[0050] LC: Length of tire crown to ground

[0051] L: Grounding length at the location of the trench

[0052] α: Correction factor

[0053] Such grooves 3 can prevent the groove depth d from becoming excessively large relative to the wear amount that varies depending on the tire's axial position, thereby improving the rigidity of the tread portion 2 and thus increasing lateral stiffness. Therefore, the tire 1 of this embodiment can maintain excellent wear resistance and improve handling stability.

[0054] As a preferred method, the groove depth d0 of the reference hypothetical groove G0 is defined based on the groove depth d of the circumferential groove 4 adjacent to the tire equator C. That is, the groove depth d0 of the reference hypothetical groove G0 is defined as the distance between the tire equator C and the curve connected by the same radius of curvature R as the outer surface 2b between the bottoms of the circumferential groove 4A of the tire crown adjacent to the tire equator C.

[0055] Figure 3 This is a schematic cross-sectional view of the tire tread section 2 of tire 1, representing a standard state of other embodiments. For example... Figure 3 As shown, in this embodiment, the tire 1 has three circumferential grooves 4 formed on its tread portion 2. One of the circumferential grooves 4 is formed on the tire equator C.

[0056] The groove depth d0 of the reference hypothetical groove G0 in this embodiment is defined as the groove depth d of the circumferential groove 4 disposed on the tire equator C. The definition of the groove depth d0 of such a reference hypothetical groove G0 is clear. Furthermore, the number of circumferential grooves 4 is not limited to this number; for example, it can be two, or it can be five or more.

[0057] like Figure 1 as well as Figure 2 As shown, the groove depth d of the circumferential groove 4 is preferably defined based on an imaginary line VL defined on the tire radial section under a standard unloaded state. In this embodiment, the imaginary line VL is defined based on the reference imaginary groove G0, the first imaginary groove G1, the second imaginary groove G2, and the third imaginary groove G3 set on the tread portion 2 in the tire radial section under a standard unloaded state.

[0058] Here, the reference imaginary groove G0 is an imaginary circumferential groove set at the tire equator C. The first imaginary groove G1 is an imaginary circumferential groove set at a first position P1, spaced axially from the tire equator C. The second imaginary groove G2 is an imaginary circumferential groove set at a second position P2, located axially outward from the first position P1. The third imaginary groove G3 is an imaginary circumferential groove set at a third position P3, located axially outward from the second position P2.

[0059] Such an imaginary line VL allows for the rationalization of the groove depth d of the circumferential groove 4 relative to the wear amount, thereby improving the rigidity of the tread 2 and thus enhancing the handling stability of the tire 1. Furthermore, the imaginary line VL helps to reduce the thickness t of the tread rubber 2g of the tread 2, enabling the tire 1 to be lighter and thus improving its fuel economy. The thickness t of the tread rubber 2g is defined as the distance between the outer surface 2b of the tread 2 and the belt layer B disposed on the tread 2.

[0060] The grounding length L includes, for example, a first grounding length L1 at a first position P1, a second grounding length L2 at a second position P2, and a third grounding length L3 at a third position P3. Such first grounding length L1, second grounding length L2, and third grounding length L3 help to define the imaginary line VL with high precision.

[0061] The trench depth d1 of the first hypothetical trench G1 is preferably defined based on the following formula (2).

[0062]

[0063] in,

[0064] d0: Depth of the baseline hypothetical trench

[0065] LC: Length of tire crown to ground

[0066] L1: First grounding length

[0067] α: Correction factor

[0068] The trench depth d2 of the second hypothetical trench G2 is preferably defined based on the following formula (3).

[0069]

[0070] in,

[0071] d0: Depth of the baseline hypothetical trench

[0072] LC: Length of tire crown to ground

[0073] L2: Second grounding length

[0074] α: Correction factor

[0075] The trench depth d3 of the third hypothetical trench G3 is preferably defined based on the following formula (4).

[0076]

[0077] in,

[0078] d0: Depth of the baseline hypothetical trench

[0079] LC: Length of tire crown to ground

[0080] L3: Third grounding length

[0081] α: Correction factor

[0082] The correction factor α is preferably a positive number of 2.0 or less. By making the correction factor α 2.0 or less, it is possible to suppress over-correction based on the difference between the crown ground length LC and the first ground length L1, the second ground length L2, and the third ground length L3. By making the correction factor α positive, it is possible to reliably make corrections based on the difference between the crown ground length LC and the first ground length L1, the second ground length L2, and the third ground length L3. From this point of view, the correction factor α is more preferably 0.8 to 1.2.

[0083] In this embodiment, the imaginary line VL is defined as being tangent to the bottom of the reference imaginary groove G0, the bottom of the first imaginary groove G1, the bottom of the second imaginary groove G2, and the bottom of the third imaginary groove G3. In this embodiment, the groove depth d of the circumferential groove 4 is within ±10% of the distance Ld from the outer surface 2b of the tread portion 2 at the axial position P of the tire where the circumferential groove 4 is formed to the imaginary line VL.

[0084] Such circumferential grooves 4 suppress excessive groove depths d relative to the wear amount varying according to the tire's axial position P, thereby improving the rigidity of the tread portion 2. Therefore, the tire 1 of this embodiment can maintain excellent wear resistance and improve handling stability.

[0085] The first position P1 is preferably located at a distance W1 that is 40% to 55% of half the ground contact width Tw from the tire equator C. The first position P1 is, for example, located in the middle land portion 6 between the circumferential groove 4A of the tire crown and the circumferential groove 4B of the tire shoulder.

[0086] The second position P2 is preferably located at a distance W2 equal to 75% to 80% of half the ground contact width Tw from the tire equator C. For example, the second position P2 is located on the tire shoulder land portion 7, which is axially outer of the tire than the shoulder circumferential groove 4B. For example, when the distance from W2 is 80% of half the ground contact width Tw, the second ground contact length L2 is equal to the tire shoulder ground contact length LS.

[0087] The third position P3 is preferably located at a distance W3 from the tire equator C, which is 90% to 85% of half the ground contact width Tw. For example, the third position P3 is located on the tire shoulder land portion 7, which is axially outer of the tire shoulder circumferential groove 4B.

[0088] Such an imaginary line VL can be defined with high precision across the entire range from the tire equator C to the contact patch Te using the reference imaginary groove G0, the first imaginary groove G1, the second imaginary groove G2, and the third imaginary groove G3.

[0089] The circumferential groove 4 in this embodiment includes a first circumferential groove on the inner side of the tire's axial direction and a second circumferential groove on the outer side of the tire's axial direction. The first circumferential groove is, for example, a crown circumferential groove 4A. The second circumferential groove is, for example, a shoulder circumferential groove 4B. In this embodiment, the depth of the second circumferential groove is greater than the depth of the first circumferential groove. Such circumferential grooves 4 leave equal grooves when the tread 2 wears, thus balancing durability and fuel economy based on lightweight design.

[0090] In this embodiment, the groove depth d of the transverse groove 5 is less than or equal to the distance Ld from the outer surface 2b at the axial position P of the tire where the transverse groove 5 is formed to the imaginary line VL. The bottom of the transverse groove 5 may extend along the imaginary line VL. Such an imaginary line VL allows for the rationalization of the maximum value of the groove depth d of the transverse groove 5.

[0091] Next, while referring to Figures 1-3 One aspect describes a method for setting the groove depth d of the circumferential grooves 4 in a tire 1 having a tread portion 2 with multiple circumferential grooves 4 extending along the tire circumference.

[0092] Figure 4 This is a flowchart illustrating the trench depth setting method of this embodiment. For example... Figure 4 As shown, the groove depth setting method of this embodiment first performs a first step S1 to determine the contact surface 2a of the tread 2 when the camber angle is 0° and a standard load is applied under standard conditions. The first step S1 can determine the contact surface 2a by, for example, using computer simulation or by experiment. This first step S1 can accurately determine the shape of the contact surface 2a.

[0093] In this embodiment, the groove depth setting method proceeds to a second step S2 after the first step S1. In this second step S2, the tire circumferential length, i.e., the contact patch length L, related to each position P along the tire axial direction of the contact patch surface 2a is calculated. In this embodiment, at least the crown contact patch length LC and the shoulder contact patch length LS are calculated in the second step S2. Preferably, the second step S2 also calculates the first contact patch length L1, the second contact patch length L2, and the third contact patch length L3. This second step S2 eliminates the need to calculate the contact patch length L related to all tire axial positions P, thus reducing calculation time.

[0094] The trench depth setting method of this embodiment proceeds to a third step S3 after the second step S2, which sets the reference imaginary trench G0, the first imaginary trench G1, the second imaginary trench G2, and the third imaginary trench G3. The third step S3, for example, determines the trench depth d0 of the reference imaginary trench G0, the trench depth d1 of the first imaginary trench G1, the trench depth d2 of the second imaginary trench G2, and the trench depth d3 of the third imaginary trench G3.

[0095] The trench depth setting method of this embodiment proceeds to a fourth step S4 after the third step S3. In the fourth step S4, an imaginary line VL is defined that is tangent to the bottom of the reference imaginary trench G0, the bottom of the first imaginary trench G1, the bottom of the second imaginary trench G2, and the bottom of the third imaginary trench G3.

[0096] In this embodiment, the groove depth setting method proceeds after the fourth step S4, followed by a fifth step S5 in which the groove depth d of the circumferential groove 4 is set such that the groove bottom is located on the imaginary line VL. This groove depth setting method rationalizes the groove depth d of the circumferential groove 4 relative to the wear amount that varies depending on the tire's axial position, thereby improving the rigidity of the tread portion 2. Therefore, the groove depth setting method of this embodiment maintains the tire 1's excellent wear resistance and improves handling stability.

[0097] Alternatively, the groove depth setting method can also replace the imaginary groove by defining an imaginary circle with a center on the outer surface 2b of the tread 2 to define the imaginary line VL.

[0098] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments, but can be implemented in various ways.

[0099] Example

[0100] Based on the specifications in Table 1, a prototype with... Figure 1 The tire is a basic structure with an embodiment having groove depths for the circumferential grooves based on formulas (2) to (4). As a comparative example, tires with equal groove depths for the circumferential grooves were prototyped. The wear resistance, handling stability, noise performance, and fuel economy of the above-mentioned prototype tires were tested. The common specifications and test methods for each prototype tire are as follows.

[0101] <Common Specifications>

[0102] Tire size: 255 / 65R18

[0103] Rim size: 18×7.5J

[0104] <Abrasion Resistance>

[0105] Each prototype tire was installed on all wheels of a vehicle and driven for 20,000 km on dry asphalt. Wear was measured at multiple locations along the tire axial direction, and the wear at the location with the most severe wear progression was evaluated. The results were expressed using an index of 100 (for Comparative Example 1). A higher index indicates less wear progression and better wear resistance.

[0106] <Maneuverability>

[0107] Each prototype tire in its standard condition was mounted on a flat-track testing machine, and its lateral stiffness was measured under a standard load and with a deviation angle of 1° while traveling at a speed of 30 km / h. The results were expressed using an index of 100 for Comparative Example 1; a larger value indicates greater lateral stiffness and better handling stability.

[0108] Noise Performance

[0109] Each prototype tire was installed on all wheels of a moving vehicle, and the external noise level was measured while the vehicle was driving on a road surface. The results were expressed using an index of 100 (for Comparative Example 1). A higher index indicates lower external noise and better noise performance.

[0110] Fuel Economy

[0111] The weight of each prototype tire was measured. The results were expressed using an index of 100 (for Comparative Example 1). A higher value indicates a lighter weight and better fuel economy.

[0112] The test results are shown in Table 1.

[0113] Table 1

[0114] Correction factor α - 0.1 1.0 2.0 Abrasion resistance (index) 100 100 100 100 Handling stability performance (index) 100 103 105 103 Noise performance (index) 100 103 105 103 Fuel Economy (Index) 100 103 105 103

[0115] The test results confirmed that, compared to the comparative example, the tires of the embodiment maintained the same wear resistance and improved handling stability, noise performance, and fuel economy.

Claims

1. A tire having a tread pattern, characterized in that, Multiple grooves are formed on the tread surface. When the tread is assembled on a standard rim and adjusted to standard internal pressure, with a camber angle of 0° and a standard load applied, the contact patch has: the tire circumferential length, i.e., the contact patch length, relative to various positions along the tire axial direction, and the distance from the tire equator to the outer end of the tire axial direction of the contact patch, i.e., the contact patch end, i.e., half the contact patch width. The ground contact length includes: the tread ground contact length at the tire equator, and the shoulder ground contact length at a position located at a distance equal to 80% of half the ground contact width from the tire equator. The crown contact length is 0.95 to 1.05 times the shoulder contact length. When a reference hypothetical groove is defined at the tire equator with a predetermined groove depth, the groove depth d of each of the plurality of grooves satisfies the following formula (1). The groove includes a plurality of circumferential grooves extending along the tire circumference. When the following are defined in the tire radial profile under the standard unloaded condition: the reference imaginary groove, a first imaginary groove at a first position spaced from the tire equator along the tire axial direction, a second imaginary groove at a second position further outward from the first position along the tire axial direction, a third imaginary groove at a third position further outward from the second position along the tire axial direction, and an imaginary line tangent to the bottom of the reference imaginary groove, the bottom of the first imaginary groove, the bottom of the second imaginary groove, and the bottom of the third imaginary groove, The depth of the circumferential groove is within ±10% of the distance from the outer surface of the tread portion at the axial position of the tire where the circumferential groove is formed to the imaginary line. The depth d1 of the first imaginary trench, the depth d2 of the second imaginary trench, and the depth d3 of the third imaginary trench are defined based on the following formulas (2) to (4). The circumferential groove includes: a crown circumferential groove disposed on or adjacent to the tire equator, and a shoulder circumferential groove disposed on the outer side of the tire axial direction of the crown circumferential groove. The depth of the shoulder circumferential groove is greater than the depth of the crown circumferential groove. The depth of the reference hypothetical groove is defined based on the depth of the circumferential groove of the tire crown. in: d0: Depth of the baseline hypothetical trench LC: Length of tire crown to ground L: Grounding length at the location of the trench L1: First grounding length L2: Second grounding length L3: Third grounding length α: Correction factor The correction factor is a positive number below 2.

0.

2. The tire according to claim 1, characterized in that, The first position is a location that is 40% to 55% of half the ground contact width away from the tire equator. The second position is a location that is 75% to 80% of the distance from the tire equator, which is half the ground contact width. The third position is a position that is 90% to 85% of the distance between the tire equator and half the ground contact width.

3. The tire according to claim 1, characterized in that, The correction factor is 0.8 to 1.

2.

4. The tire according to claim 1 or 2, characterized in that, The groove includes multiple transverse grooves extending along the tire axial direction.

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