Pneumatic tires

Abstract

A pneumatic tire. The durability of the bead portion is improved. The pneumatic tire (1) includes a bead reinforcement layer (8). The bead reinforcement layer (8) is arranged on the axially outer side of the folded portion (6b) of the carcass (6), and extends radially inward and outward of the tire in a manner covering the outer end (6e) of the folded portion (6b). A recess row (9R) formed by forming a plurality of recesses (9) along the circumferential direction of the tire is provided on the outer surface (4a) of the bead portion (4). The outer end (8e) of the bead reinforcement layer (8) is closer to the outer side of the tire radial direction than the outer end (9e) of the recess (9).

Description

Technical Field

[0001] The present invention relates to a pneumatic tire. Background Art

[0002] The following Patent Document 1 describes a heavy-duty pneumatic tire that aims to improve the durability of the bead portion. The heavy-duty pneumatic tire has a reinforcing layer composed of an organic fiber cord layer on the outside of the folded portion of the carcass ply that is prone to damage. Such a reinforcing layer has the function of dispersing the deformation of the bead portion during driving.

[0003] Patent document: Japanese Patent Application Publication No. 2018-111433 Summary of the invention

[0004] However, when a reinforcing layer is provided in the bead portion, deformation tends to concentrate near the outer end of the reinforcing layer in the tire radial direction during running of the tire, and this portion becomes the starting point of damage such as loosening, which poses a new problem.

[0005] The inventors have conducted intensive studies and found that turbulence is generated around the bead portion when the tire is running, and utilizing this turbulence to cool the vicinity of the outer end of the reinforcing layer is effective in suppressing damage near the reinforcing layer.

[0006] 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 pneumatic tire capable of improving the durability performance of a bead portion.

[0007] The present invention provides an inflatable tire, wherein the inflatable tire includes: a pair of bead portions, each of which has a bead core embedded therein; a carcass spanning the pair of bead portions; and a bead reinforcement layer, each of which is arranged on the pair of bead portions, the carcass including a carcass cord layer, the carcass cord layer including a main body portion extending between the bead cores, and a folded portion folded back from the inner side to the outer side in the tire axial direction around each bead core, the bead reinforcement layer is arranged on the outer side of the folded portion in the tire axial direction, and extends radially inward and outward of the tire in a manner covering the outer end of the folded portion in the tire radial direction, and a row of recesses formed by a plurality of recesses is provided on the outer surface of the bead portion along the circumferential direction of the tire, and the outer end of the bead reinforcement layer in the tire radial direction is closer to the outer side in the tire radial direction than the outer end of the recess in the tire radial direction.

[0008] In the pneumatic tire of the present invention, preferably, the bead reinforcing layer is a nylon cord ply formed by covering a plurality of nylon cords with a topping rubber.

[0009] In the pneumatic tire of the present invention, it is preferable that the recessed portions are arranged at equal intervals in the tire circumferential direction.

[0010] In the pneumatic tire of the present invention, preferably, the depth h of the recessed portion is 1.0 mm to 5.0 mm.

[0011] In the pneumatic tire of the present invention, it is preferable that the recessed portion row is arranged on the inner side in the tire radial direction relative to a tire maximum width position.

[0012] In the pneumatic tire of the present invention, preferably, a ratio (p / h) of a pitch p of the recessed portions in the tire circumferential direction to a depth h of the recessed portions is 1.0 to 30.0.

[0013] In the pneumatic tire of the present invention, preferably, a distance in the tire radial direction between an outer end in the tire radial direction of the bead reinforcing layer and an outer end in the tire radial direction of the recessed portion is 3.0 mm or more.

[0014] In the pneumatic tire of the present invention, preferably, the bead reinforcement layer includes a first reinforcement layer and a second reinforcement layer, and the outer end of the second reinforcement layer in the tire radial direction is arranged radially inward of the outer end of the first reinforcement layer in the tire radial direction.

[0015] In the pneumatic tire of the present invention, it is preferable that at least one of an outer end in the tire radial direction of the second reinforcing layer and an outer end in the tire radial direction of the folded portion overlaps with the recessed portion in the tire radial direction.

[0016] In the pneumatic tire of the present invention, it is preferable that the first reinforcing layer be arranged on the outer side in the tire axial direction of the second reinforcing layer.

[0017] In the pneumatic tire of the present invention, preferably, the recess row includes an outer recess row and an inner recess row arranged on the inner side of the outer recess row in the tire radial direction, and the recesses of the outer recess row and the recesses of the inner recess row are arranged in a staggered manner in the tire circumferential direction.

[0018] In the pneumatic tire of the present invention, it is preferable that the pneumatic tire is a heavy-load pneumatic tire.

[0019] The present invention can improve the durability of the bead portion by adopting the above-mentioned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a cross-sectional view of a pneumatic tire according to one embodiment of the present invention.

[0021] Figure 2 yes Figure 1 A partial stereoscopic view of a pneumatic tire.

[0022] Figure 3 yes Figure 1 Magnified image of .

[0023] Figure 4 yes Figure 1 Magnified image of .

[0024] Description of symbols

[0025] 1: pneumatic tire; 4: bead portion; 4a: outer surface; 6: carcass; 6b: folded portion; 6e: outer end; 8: bead reinforcing layer; 8e: outer end; 9: recessed portion; 9e: outer end; 9R: recessed portion row. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described in detail.

[0027] Figure 1 It is a tire meridian cross-sectional view including a tire rotation axis (not shown) in one standard state of a pneumatic tire (hereinafter sometimes simply referred to as a “tire”) according to the present embodiment. Figure 1 For example, a heavy-duty tire 1 is shown. However, the present invention can also be applied to a tire 1 for a passenger car or a light truck.

[0028] The "standard state" is an unloaded state in which the tire 1 is assembled on a standard rim (not shown) and filled with a standard internal pressure. In this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in the standard state.

[0029] The "standard rim" is a rim of a specification determined according to the tire in the specification system including the specification based on the tire 1, for example, in the case of JATMA, it is "standard rim", in the case of TRA, it is "design rim", and in the case of ETRTO, it is "measuring rim". The "standard internal pressure" is the air pressure of each specification specified for the tire in the specification system including the specification based on the tire 1, in the case of JATMA, it is "maximum air pressure", in the case of TRA, it is the maximum value recorded in the table "TIRELOADLIMITSAT VARIOUSCOLD INFLATION PRESSURES", and in the case of ETRTO, it is "INFLATION PRESSURE".

[0030] like Figure 1 As shown, the tire 1 of this embodiment includes: a pair of bead portions 4 in which bead cores 5 are embedded, a carcass 6 spanning between the pair of bead portions 4 , and bead reinforcing layers 8 disposed on the pair of bead portions 4 .

[0031] The carcass 6 includes a carcass ply 6A including a main body portion 6a extending between the bead cores 5, 5 and a folded portion 6b folded around each bead core 5 from the inner side to the outer side in the tire axial direction.

[0032] The bead reinforcing layer 8 is arranged outside the folded portion 6b in the tire axial direction and extends radially inward and outward to cover the radially outer end 6e of the folded portion 6b. Such a bead reinforcing layer 8 suppresses peeling of the folded portion 6b and improves the durability of the bead portion 4.

[0033] Figure 2 is a partial stereogram of the tire 1. Figure 2 As shown, the tire 1 of this embodiment is formed with a recess row 9R having a plurality of recesses 9 formed along the tire circumferential direction on the outer surface 4a of the bead portion 4. Such a recess row 9R generates a turbulent flow f on the outer surface 4a of the bead portion 4 when the tire 1 is running. The turbulent flow f takes low-temperature air from the outer side of the tire into the outer surface 4a of the bead portion 4. The low-temperature air is transferred to the outer side in the tire radial direction by the centrifugal force generated by the rotation of the tire, and the outer area of ​​the recess row 9R of the bead portion 4 in the tire radial direction is cooled.

[0034] Figure 3 4 is an enlarged view of the tire bead portion 4. Figure 3 As shown, the outer end 8e of the bead reinforcing layer 8 in the tire radial direction is closer to the outer side in the tire radial direction than the outer end 9e of the recessed portion 9 in the tire radial direction. Thus, the low-temperature air cools the outer end 8e of the bead reinforcing layer 8 to suppress damage there. Therefore, the tire 1 of this embodiment improves the durability of the bead portion 4.

[0035] In order to effectively exert the above-mentioned effect, the distance La in the tire radial direction between the outer end 8e of the bead reinforcing layer 8 and the outer end 9e of the recessed portion 9 is preferably 3.0 mm or more. If the distance La is too large, the contact between the cold air and the outer end 8e of the bead reinforcing layer 8 is suppressed. Therefore, the distance La is preferably 10.0 mm or less.

[0036] The length L1 in the tire radial direction between the inner end 9i and the outer end 9e of the recessed portion 9 is preferably, for example, 35% to 55% of the length L2 in the tire radial direction of the bead reinforcement layer 8. Since the length L1 of the recessed portion 9 is 35% or more of the length L2 of the bead reinforcement layer 8, damage to the bead reinforcement layer 8 can be effectively suppressed. Since the length L1 of the recessed portion 9 is 55% or less of the length L2 of the bead reinforcement layer 8, a reduction in the rigidity of the bead portion 4 can be suppressed.

[0037] When the standard rim R is mounted on the tire 1 , the inner end 9 i of the recessed portion 9 is located, for example, outside in the tire radial direction relative to the outer end Rm of the standard rim R in the tire radial direction.

[0038] The depth of the recessed portion 9 is preferably 1.0 mm to 5.0 mm. Since the depth is 1.0 mm or more, turbulence can be generated on the outer surface 4a. Since the depth h is 5.0 mm or less, excessive turbulence will not be generated, and the rolling resistance performance of the tire 1 can be maintained at a high level. In addition, a significant decrease in the rigidity of the bead portion 4 can be suppressed. From this point of view, the depth h is more preferably 2.0 mm or more, and more preferably 4.0 mm or less.

[0039] In the present embodiment, the recessed portion row 9R is arranged at a position smaller than the tire maximum width position M ( Figure 1 The recessed portion row 9R is arranged on the inner side of the tire radial direction than the tire maximum width position M. Such a recessed portion row 9R helps to reduce the heat generation of the bead portion 4. In addition, since the recessed portion row 9R is arranged on the inner side of the tire radial direction than the tire maximum width position M, the resistance to tire rotation becomes smaller than when it is arranged on the outer side of the tire radial direction than the tire maximum width position M, and the increase in rolling resistance can be suppressed. In this specification, the tire maximum width position M is the position where the main body 6a of the carcass ply 6A is the outermost position in the tire axial direction.

[0040] The recesses 9 of the recess row 9R are arranged at equal intervals in the tire circumferential direction, for example. As a result, the turbulent flows f generated by the recesses 9 are generated at equal intervals, so that the outer surface 4a of the bead portion 4 can be effectively cooled. The "equal interval" mentioned above is of course the same interval in the dictionary, but it can also include a mode in which the difference (Px-Pi) between the maximum interval Px and the minimum interval Pi (omitted from the figure) is less than 0.2 times the maximum interval Px.

[0041] like Figure 2 As shown, the recessed portion row 9R includes, for example, recessed portions 9 and smooth portions 10 formed between adjacent recessed portions 9 in the tire circumferential direction, and the recessed portions 9 and the smooth portions 10 are alternately arranged in the tire circumferential direction. The smooth portions 10 are formed, for example, in a manner smoothly connected to the outer surface 3a of the sidewall portion 3. In addition, the recessed portion row 9R is not limited to such a manner.

[0042] In the side view of the tire 1, the recess 9 is formed in a rectangular shape in this embodiment. The recess 9 has a pair of longitudinal edges 11, 11 extending in the tire radial direction. Such a recess 9 effectively generates turbulent flow f at the longitudinal edges 11. In addition, the recess 9 is not limited to a rectangular shape, and various shapes such as a circular shape, an elliptical shape, a triangular shape, and a polygonal shape can be adopted.

[0043] The ratio (P / h) of the interval P of the recessed portion 9 in the tire circumferential direction to the depth h of the recessed portion 9 is preferably 1.0 to 30.0. By setting the ratio (P / h) within such a range, turbulent flow f can be effectively generated on the outer surface 4a of the bead portion 4. The ratio (P / h) is more preferably 3.0 or more, and further preferably 5.0 or more. The ratio (P / h) is more preferably 25.0 or less, and further preferably 20.0 or less.

[0044] The ratio (w / P) of the length w of the recessed portion 9 in the tire circumferential direction to the interval P of the recessed portion 9 is preferably, for example, 0.60 to 0.90. Since the ratio (w / P) is 0.60 or more, turbulence can be effectively generated. Since the ratio (w / P) is 0.90 or less, the reduction in the rigidity of the bead portion 4 can be suppressed. In order to effectively exert such an effect, the ratio (w / P) is more preferably 0.70 or more, and further preferably 0.80 or less.

[0045] In order to achieve the same effect, the ratio (h / w) of the length w of the recess 9 in the tire circumferential direction to the depth h is preferably 0.03 or more, more preferably 0.05 or more. The ratio (h / w) is preferably 0.10 or less, more preferably 0.08 or less. Figure 3 The ratio of the length w in the tire circumferential direction (r / w) is, for example, preferably not less than 0.25, more preferably not less than 0.30, and preferably not more than 0.55, more preferably not more than 0.50.

[0046] The recessed portion row 9R of the present embodiment includes an outer recessed portion row 14 and an inner recessed portion row 15 arranged on the inner side of the outer recessed portion row 14 in the tire radial direction. In the present embodiment, the recessed portions 9 of the outer recessed portion row 14 and the recessed portions 9 of the inner recessed portion row 15 are arranged in a staggered manner in the tire circumferential direction. By such an arrangement, it is possible to suppress a reduction in the rigidity of the bead portion 4. In the present embodiment, the recessed portions 9 of the outer recessed portion row 14 and the recessed portions 9 of the inner recessed portion row 15 are formed in the same number.

[0047] In this embodiment, the carcass ply 6A is formed by covering carcass cords arranged at an angle of 70 degrees or more relative to the tire equator with a topping rubber (not shown). The carcass cords are preferably organic fiber cords such as nylon, polyester or rayon, or steel cords.

[0048] In the present embodiment, the bead reinforcement layer 8 is a nylon cord ply 17 formed by covering a plurality of nylon cords with a topping rubber. Preferably, the composite elastic modulus E*1 of the topping rubber of the bead reinforcement layer 8 is, for example, greater than or less than or equal to the composite elastic modulus E*2 of the topping rubber of the carcass ply 6A. The composite elastic modulus E*1 of the topping rubber of the bead reinforcement layer 8 is, for example, preferably greater than 3.0 MPa, more preferably greater than 5.0 MPa, preferably less than 8.0 MPa, more preferably less than 7.0 MPa. In this specification, the composite elastic modulus is a value measured using a viscoelastic spectrometer manufactured by Iwamoto Manufacturing Co., Ltd. under the following conditions based on the provisions of JIS-K6394.

[0049] Initial deformation: 10%

[0050] Amplitude: ±2%

[0051] Frequency: 10Hz

[0052] Deformation Mode: Stretch

[0053] Measuring temperature: 70℃

[0054] Figure 4 4 is an enlarged view of the tire bead portion 4. Figure 4 As shown, the bead reinforcement layer 8 of the present embodiment includes a first reinforcement layer 18 and a second reinforcement layer 19. The outer end 19e of the second reinforcement layer 19 in the tire radial direction is, for example, closer to the inner side of the tire radial direction than the outer end 18e of the first reinforcement layer 18 in the tire radial direction. In this way, since the two outer ends 18e and 19e are offset in the tire radial direction, the rigidity difference that greatly changes the rigidity of the bead portion 4 in the tire circumferential direction is suppressed, so that the durability of the bead portion 4 is improved.

[0055] The first reinforcing layer 18 is, for example, disposed on the outer side of the second reinforcing layer 19 in the tire axial direction. Such a first reinforcing layer 18 suppresses the peeling of the second reinforcing layer 19 and improves the rigidity of the bead portion 4. The distance L3 in the tire radial direction between the outer end 18e of the first reinforcing layer 18 and the bead reference line BL is, for example, preferably equal to the tire cross-sectional height H( Figure 1 The bead reference line BL is equivalent to the tire axial line that specifies the rim diameter of the standard rim (see JATMA).

[0056] At least one of the outer end 19e of the second reinforcing layer 19 or the outer end 6e of the folded portion 6b overlaps with the recess 9 in the tire radial direction, for example. The turbulent flow f generated in the recess 9 effectively discharges the heat from the surface (bottom) 9s of the recess 9. As a result, the heat of the outer end 19e of the second reinforcing layer 19 or the outer end 6e of the folded portion 6b is removed, so that damage to these outer ends 19e, 6e is suppressed. In the tire 1 of the present embodiment, the outer end 19e of the second reinforcing layer 19 and the outer end 6e of the folded portion 6b both overlap with the recess 9 in the tire radial direction. In the present embodiment, the outer end 19e of the second reinforcing layer 19 is closer to the outside of the tire radial direction than the outer end 6e of the folded portion 6b.

[0057] The bead reinforcing layer 8 extends inward in the tire radial direction from the inner end 5i in the tire radial direction of the bead core 5. Such a bead reinforcing layer 8 further improves the durability of the bead portion 4.

[0058] The shortest distance Lb between the bead reinforcing layer 8 and the recessed portion 9 is preferably, for example, 1.5 times or more, preferably 3.5 times or less, of the depth h of the recessed portion 9. Since the shortest distance Lb is 1.5 times or more, the rigidity of the bead portion 4 can be maintained at a high level, and the durability performance can be improved. Since the shortest distance Lb is 3.5 times or less, the heat generated in the bead reinforcing layer 8 can be effectively removed from the outer surface 4a and the surface 9s. In order to effectively play such a role, the shortest distance Lb is more preferably 2.0 times or more, and more preferably 3.0 times or less, of the depth h.

[0059] like Figure 1 As shown, the tire 1 includes, for example, a belt layer 7 disposed on the tread portion 2, a bead apex rubber 20 disposed on each bead portion 4, a lip rubber 21, and a sidewall rubber 22 disposed on each sidewall portion 3. The belt layer 7 and the bead apex rubber 20 are formed of a known structure.

[0060] The belt layer 7 is formed of, for example, a plurality of belt plies using steel belt cords. The belt layer 7 of the present embodiment is formed of, for example, four belt plies 7A to 7D arranged inside and outside the tire radial direction.

[0061] The bead apex 20 is provided, for example, between the main body 6a and the folded portion 6b and outside the bead core 5 in the tire radial direction. The outer end 20e of the bead apex 20 is outside the outer end 8e of the bead reinforcing layer 8 in the tire radial direction.

[0062] The bead rubber 21 is disposed adjacent to the outer side of the bead reinforcing layer 8 in the tire axial direction so as to cover the outer end 8e of the bead reinforcing layer 8. In the present embodiment, the bead rubber 21 forms the outer surface 4a of the bead portion 4.

[0063] The sidewall rubber 22 extends, for example, from a position radially outward from the tire maximum width position M to the radially inward side of the inner end 9i of the recessed portion 9. In the present embodiment, the sidewall rubber 22 is formed with the recessed portion 9.

[0064] like Figure 4 As shown, the sidewall rubber 22 of this embodiment overlaps the edge rubber 21 in the tire radial direction in the region where the recessed portion 9 is formed. In this embodiment, the sidewall rubber 22 forms the outer surface 4a of the bead portion 4 and the outer surface 3a of the sidewall portion 3.

[0065] The bead portion 4 of the present embodiment is provided with a U-shaped reinforcing layer 24 disposed between the bead reinforcing layer 8 and the carcass 6. The U-shaped reinforcing layer 24 is, for example, a cord ply formed by covering a plurality of steel cords or organic fiber cords with a topping.

[0066] In the present embodiment, the U-shaped reinforcing layer 24 extends along the carcass 6 to prevent the bead reinforcing layer 8 from contacting the carcass 6. The U-shaped reinforcing layer 24 of the present embodiment includes a first portion 24a extending along the main body 6a and a second portion 24b extending along the folded portion 6b. The outer end 24e of the second portion 24b in the tire radial direction is, for example, closer to the outer side in the tire radial direction than the inner end 9i of the recess 9. The outer end 24e of the second portion 24b overlaps with the recess 9 in the tire radial direction. Thus, damage to the second portion 24b can be suppressed.

[0067] As mentioned above, although the particularly preferred embodiment of the present invention has been described in detail, the present invention is not limited to the illustrated embodiment, and can be implemented in various modified forms.

[0068] [Example]

[0069] Based on the specifications in Table 1 and Table 2, we have produced Figure 1 The basic structure of the heavy-duty pneumatic tire is 275 / 80R22.5. Then, the durability, rolling resistance and the temperature of the outer surface of the bead portion of each test tire were tested. In addition, the general specifications and test methods of each test tire are as follows.

[0070] Use rim: 22.5×8.25

[0071] Lb is the same in each example in Table 1. Lb+h is the same in each example in Table 2. P and w are the same in each example in Table 1 and Table 2.

[0072] <Durability>

[0073] Each test tire was run on a drum under the following conditions, and the running distance until the bead portion was damaged was measured. The test results were expressed as an index with Comparative Example 1 being 100. The larger the value, the better.

[0074] Internal pressure: 1075kPa

[0075] Load: 81.28kN

[0076] Speed: 20km / h

[0077] <Rolling resistance performance·Outer surface temperature>

[0078] Using a rolling resistance tester, after running for 1 hour under the following conditions, the rolling resistance and the temperature of the outer surface of the bead portion of each test tire were measured. The test results of the rolling resistance performance were expressed as an index with Comparative Example 1 being 100. The test results of the outer surface temperature were expressed as the difference from the temperature of Comparative Example 1. The smaller the value, the better.

[0079] Internal pressure: 850kPa

[0080] Load: 27.09kN

[0081] Speed: 80km / h

[0082]

Table 1

[0083]

[0084]

Table 2

[0085]

[0086] As shown in the table, the tires of the examples have excellent durability performance. In addition, the temperature of the outer surface of the tires of the examples is low, and the rolling resistance performance is also excellent.

Claims

1. A pneumatic tire, wherein: The pneumatic tire comprises: a pair of bead parts, each of which has a bead core embedded therein; a carcass spanning between the pair of bead parts; and a bead reinforcing layer, each of which is disposed on the pair of bead parts. The carcass includes a carcass ply including a main body portion extending between the bead cores and a folded portion folded around each bead core from the inner side to the outer side in the tire axial direction. The bead reinforcing layer is arranged on the outer side of the folded portion in the tire axial direction and extends inward and outward in the tire radial direction so as to cover the outer end of the folded portion in the tire radial direction. The outer surface of the bead portion has a recess row formed with a plurality of recesses along the tire circumferential direction. The outer end of the bead reinforcing layer in the tire radial direction is located farther outward in the tire radial direction than the outer end of the recessed portion in the tire radial direction. The bead reinforcement layer comprises a first reinforcement layer and a second reinforcement layer, The outer end of the second reinforcing layer in the tire radial direction is arranged on the inner side in the tire radial direction than the outer end of the first reinforcing layer in the tire radial direction. At least one of an outer end of the second reinforcing layer in the tire radial direction and an outer end of the folded portion in the tire radial direction overlaps with the recessed portion in the tire radial direction.

2. The pneumatic tire according to claim 1, wherein: The tire bead reinforcement layer is a nylon cord fabric layer formed by covering a plurality of nylon cords with rubber.

3. The pneumatic tire according to claim 1 or 2, wherein: The recessed portions are arranged at equal intervals in the tire circumferential direction.

4. The pneumatic tire according to claim 1 or 2, wherein: The depth h of the recess is 1.0 mm to 5.0 mm.

5. The pneumatic tire according to claim 1 or 2, wherein: The recessed portion row is arranged on the inner side in the tire radial direction relative to the tire maximum width position.

6. The pneumatic tire according to claim 1 or 2, wherein: A ratio (p / h) of a pitch p of the recessed portions in the tire circumferential direction to a depth h of the recessed portions is 1.0 to 30.

0.

7. The pneumatic tire according to claim 1 or 2, wherein: A distance in the tire radial direction between an outer end of the bead reinforcing layer in the tire radial direction and an outer end of the recessed portion in the tire radial direction is 3.0 mm or more.

8. The pneumatic tire according to claim 1 or 2, wherein: The first reinforcement layer is disposed on the outer side of the second reinforcement layer in the tire axial direction.

9. The pneumatic tire according to claim 1 or 2, wherein: The recessed portion row includes an outer recessed portion row and an inner recessed portion row arranged on the inner side in the tire radial direction than the outer recessed portion row. The recessed portions of the outer recessed portion row and the recessed portions of the inner recessed portion row are arranged in a staggered pattern in the tire circumferential direction.

10. The pneumatic tire according to claim 1 or 2, wherein: The pneumatic tire is a heavy-load pneumatic tire.

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