Pneumatic tire

Abstract

The present invention addresses the problem of providing a pneumatic tire capable of reducing cavity resonance sound with a simple configuration. A pneumatic tire (1) includes a tread portion (2), a pair of sidewall portions (3) extending from both sides of the tread portion (2) in a tire axial direction to an inner side in a tire radial direction, a pair of bead portions (4) located on an inner side in the tire radial direction of the pair of sidewall portions (3), and a plurality of Helmholtz mufflers (9) disposed on a tire inner cavity surface (1i). The plurality of Helmholtz mufflers (9 bags) include a first muffler (9A) having a first resonance frequency f1 and a second muffler (9B) having a second resonance frequency f2 different from the first resonance frequency f1. The first muffler (9A) and the second muffler (9B) are respectively disposed on the inner side of at least one of the pair of sidewall sections (3) and the pair of bead sections (4) in the axial direction of the tire.

Description

Technical Field

[0001] The present invention relates to a pneumatic tire capable of reducing cavity resonance sound. Background Art

[0002] Conventionally, pneumatic tires having a device for reducing the resonance sound in the tire cavity generated during driving are known. For example, Patent Document 1 below proposes a pneumatic tire having a plurality of resonators as Helmholtz resonators mounted on the inner circumference of the tire. [Prior art literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent No. 6289506 Summary of the invention [Problems to be solved by the invention]

[0004] However, the pneumatic tire of Patent Document 1 needs a plurality of Helmholtz mufflers having different resonance frequencies in order to cope with the cavity resonance sound in the tire that varies with the running speed, and further improvements are required in terms of manufacturing and weight.

[0005] The present invention is proposed in view of the above-mentioned actual situation, and its main purpose is to provide a pneumatic tire capable of reducing cavity resonance sound with a simple structure.

Methods for solving the problem

[0006] The present invention is an inflatable tire, comprising: a tread portion, a pair of sidewall portions extending from both sides of the tread portion in the tire axial direction toward the inner side of the tire radial direction, a pair of bead portions located on the inner side of the pair of sidewall portions in the tire radial direction, and a plurality of Helmholtz-type mufflers arranged on the inner cavity surface of the tire; the plurality of Helmholtz-type mufflers include: a first muffler having a first resonance frequency, and a second muffler having a second resonance frequency different from the first resonance frequency; the first muffler and the second muffler are respectively arranged on the inner side of at least one of the pair of sidewall portions and the pair of bead portions in the tire axial direction. [Effects of the Invention]

[0007] The pneumatic tire of the present invention has the above-mentioned structure, and can reduce the cavity resonance sound with a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0009] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Figure 1 The figure shows a tire meridian cross-section of the pneumatic tire 1 in the normal state of the present embodiment. Here, the "normal state" means that the pneumatic tire 1 is mounted on a normal rim and is in an unloaded state adjusted to a normal internal pressure. In the following, unless otherwise specified, the dimensions of various parts of the pneumatic tire 1 are values ​​measured in the normal state.

[0010] The "regular rim" refers to a rim specified for each tire in a specification system including the specification to which the pneumatic tire 1 is based, for example, a "standard rim" in JATMA, a "design rim" in TRA, and a "measuring rim" in ETRTO. If there is no specification system including the specification to which the pneumatic tire 1 is based, the "regular rim" is a rim with the smallest rim diameter and the smallest rim width among rims that can be mounted on the rim without causing air leakage.

[0011] “Normal internal pressure” refers to the air pressure specified for each tire in each specification when there is a specification system including the specification to which the pneumatic tire 1 is based, and refers to the “maximum air pressure” in JATMA, the maximum value recorded in the table “TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES” in TRA, and “INFLATION PRESSURE” in ETRTO. When there is no specification system including the specification to which the pneumatic tire 1 is based, the “Normal internal pressure” is the air pressure specified for each tire by the manufacturer, etc.

[0012] like Figure 1 As shown, the pneumatic tire 1 of this embodiment is suitable for use as a tire for a passenger car. The pneumatic tire 1 is not limited to a tire for a passenger car, but can be applied to various tires such as a heavy-duty tire, a two-wheeled vehicle tire, a racing vehicle tire, and an industrial vehicle tire.

[0013] The pneumatic tire 1 of the present embodiment includes a tread portion 2, a pair of sidewall portions 3, and a pair of bead portions 4. The sidewall portions 3 are, for example, portions extending radially inward from both sides of the tread portion 2 in the tire axial direction. The bead portions 4 are, for example, portions located radially inward of the sidewall portions 3. The bead portions 4 of the present embodiment are portions that come into contact with a regular rim.

[0014] Each of the pair of bead portions 4 has, for example, an annular bead core 5 extending in the tire circumferential direction, and a bead apex rubber 8 extending from the bead core 5 to the outer side of the tire radial direction. The bead core 5 is formed of, for example, a steel wire. The bead apex rubber 8 is formed of, for example, hard rubber. Such a bead portion 4 has high rigidity, so it can suppress deformation during driving, which helps to reduce the cavity resonance sound of the pneumatic tire 1.

[0015] The pneumatic tire 1 of this embodiment includes a carcass 6 extending between a pair of bead portions 4, and a belt layer 7 disposed on the tread portion 2. The belt layer 7 is disposed, for example, on the tire radially outer side of the carcass 6. The pneumatic tire 1 preferably has a tire inner cavity surface 1i defining the tire inner cavity on the inner side of the carcass 6.

[0016] Figure 2 1 is a schematic cross-sectional view of a pneumatic tire 1 viewed from the tire axial direction. Figure 1 and Figure 2 As shown, the pneumatic tire 1 of this embodiment has a plurality of Helmholtz mufflers 9 arranged on the tire inner cavity surface 1i. The plurality of Helmholtz mufflers 9 of this embodiment include: a first muffler 9A having a first resonance frequency f1, and a second muffler 9B having a second resonance frequency f2 different from the first resonance frequency f1. Such a pneumatic tire 1 can reduce the cavity resonance sound in the tire that varies with the running speed by resonating with a plurality of frequencies.

[0017] The first muffler 9A and the second muffler 9B of the present embodiment are respectively arranged on the inner side of the tire axial direction of at least one of the sidewall portion 3 and the bead portion 4. Such a Helmholtz muffler 9 can suppress the change of the Helmholtz muffler 9 itself even when the tread portion 2 is deformed when contacting the ground, and can suppress the resonance sound generated by the Helmholtz muffler 9 due to the impact when contacting the ground. Therefore, the pneumatic tire 1 of the present embodiment can reduce the cavity resonance sound with a simple structure.

[0018] As a more preferred embodiment, the first resonance frequency f1 is the maximum resonance frequency fmax in a frequency band including the resonance frequencies f of the plurality of Helmholtz mufflers 9. The second resonance frequency f2 of the present embodiment is the minimum resonance frequency fmin in a frequency band including the resonance frequencies f of the plurality of Helmholtz mufflers 9.

[0019] The difference (f1-f2) between the first resonance frequency f1 and the second resonance frequency f2 is preferably 10 to 90 Hz. Such a pneumatic tire 1 can effectively reduce the cavity resonance sound generated by a driving speed of 10 to 200 km / h, and can suppress the number of Helmholtz mufflers 9. Therefore, the pneumatic tire 1 of the present embodiment can reduce the cavity resonance sound by a simple structure. Based on this viewpoint, the difference (f1-f2) between the first resonance frequency f1 and the second resonance frequency f2 is more preferably 10 to 60 Hz.

[0020] The first resonance frequency f1 of the Helmholtz muffler 9 is preferably 130 to 350 Hz. The second resonance frequency f2 of the Helmholtz muffler 9 is preferably 120 to 340 Hz. Such a Helmholtz muffler 9 can cope with the frequency band of the cavity resonance sound generated by the tire for a passenger car, and can effectively reduce the cavity resonance sound of the tire for a passenger car.

[0021] For example, the plurality of Helmholtz mufflers 9 may have at least one resonance frequency f different from the first resonance frequency f1 and the second resonance frequency f2. Such a Helmholtz muffler 9 can resonate with a wide frequency band of the cavity resonance sound, and can more reliably reduce the cavity resonance sound.

[0022] In the plurality of Helmholtz mufflers 9, it is preferred that the unit width df is substantially equal, and the unit width df is the difference between the resonance frequencies f of a group of adjacent ones in the frequency band. Here, the unit width df being substantially equal means that the difference between the unit widths df is less than 10% of the unit width df. Such a Helmholtz muffler 9 can absorb sound uniformly in the entire frequency band.

[0023] The unit width df of the plurality of Helmholtz mufflers 9 is preferably 3 to 10 Hz. Such Helmholtz mufflers 9 can uniformly absorb sound in the entire frequency band without excessively increasing the number of types thereof.

[0024] The first muffler 9A and the second muffler 9B are preferably arranged on the tire axial inner side of the bead portion 4. Such a Helmholtz muffler 9 does not generate resonance sound in the Helmholtz muffler 9 due to the impact at the time of ground contact, and can more reliably reduce the cavity resonance sound.

[0025] The first muffler 9A and the second muffler 9B are respectively arranged on the inner side of the tire axial direction, for example, from the inner end 5e of the bead core 5 in the tire radial direction to the outer end 8e of the bead apex 8 in the tire radial direction. That is, the plurality of Helmholtz mufflers 9 are preferably respectively arranged in the range of height H from the inner end 5e of the bead core 5 to the outer end 8e of the bead apex 8. Since such Helmholtz mufflers 9 are arranged in a range having high rigidity, the cavity resonance sound can be more reliably reduced.

[0026] Even when the first muffler 9A and the second muffler 9B are respectively arranged on the inner side of the tire axial direction of the sidewall portion 3, they are preferably arranged on the inner side of the tire radial direction than the outer ends 6e of the carcass plies 6A and 6B. Such a Helmholtz muffler 9 helps suppress the resonance sound generated by the Helmholtz muffler 9 due to the impact when touching the ground.

[0027] like Figure 1 As shown, the carcass 6 has at least one carcass ply, and in this embodiment, two carcass plies 6A and 6B. The two carcass plies 6A and 6B include, for example, a first carcass ply 6A located radially inward of the tread portion 2, and a second carcass ply 6B located radially outward of the first carcass ply 6A.

[0028] Preferably, at least one of the carcass plies 6A and 6B includes a main body 6a and a folded portion 6b, wherein the main body 6a extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and the folded portion 6b is connected to the main body 6a and folded back from the tire axis toward the inside to the outside around the bead core 5. The first carcass ply 6A and the second carcass ply 6B of this embodiment include a main body 6a and a folded portion 6b, respectively. Such a carcass 6 helps to improve the rigidity of the bead portion 4 and reduce the cavity resonance sound of the pneumatic tire 1.

[0029] Preferably, the outer end 6e of the folded portion 6b of at least one of the carcass plies 6A and 6B in the tire radial direction is located on the outer side in the tire radial direction relative to the tire maximum width position P where the tire cross-sectional width W is the largest. In the carcass 6, for example, the outer end 6e of the folded portion 6b of the first carcass ply 6A is located on the outer side in the tire radial direction relative to the tire maximum width position P, and the outer end 6e of the folded portion 6b of the second carcass ply 6B is located on the inner side in the tire radial direction relative to the tire maximum width position P. Such a carcass 6 can achieve both rigidity and lightness of the sidewall portion 3, and can reduce the cavity resonance sound and rolling resistance of the pneumatic tire 1.

[0030] The carcass cords 6A and 6B include, for example, carcass cords (not shown) made of organic fiber cords. Examples of the organic fiber cords include cords of one or more mixed fibers selected from the group consisting of polyethylene terephthalate fibers, polyethylene naphthalate fibers, nylon fibers, aramid fibers, and rayon fibers.

[0031] The carcass cords are preferably arranged at an angle of 25 to 90° relative to the tire circumferential direction. When the carcass cords are inclined at an angle less than 90° relative to the tire circumferential direction, the carcass cords of the first carcass cord 6A and the carcass cords of the second carcass cord 6B are preferably inclined in opposite directions relative to the tire circumferential direction. For example, the carcass 6 may adopt an offset structure. Here, the angle of the carcass cords is the angle in the pneumatic tire 1 in a normal state, and can be confirmed by, for example, partially peeling off the tread portion 2.

[0032] The belt layer 7 includes at least one, preferably two or more belt layers, and in the present embodiment, includes two belt layers 7A and 7B. The two belt layers 7A and 7B include, for example, a first belt layer 7A located radially inwardly of the tire, and a second belt layer 7B located outside the first belt layer 7A. The outer end 7e of the belt layer 7 in the present embodiment is the outer end 7e of the first belt layer 7A in the tire axial direction. Such a belt layer 7 can improve the rigidity of the tread portion 2 and can reduce the cavity resonance sound of the pneumatic tire 1.

[0033] The belt layers 7A and 7B include belt cords (not shown) composed of, for example, steel cords. The belt cords may be, for example, single steel wires or twisted wires formed by twisting a plurality of steel monofilaments.

[0034] The belt cords are arranged at an angle of 10 to 30 degrees relative to the tire circumferential direction, for example. Preferably, the belt cords of the first belt ply 7A and the belt cords of the second belt ply 7B are inclined in opposite directions relative to the tire circumferential direction. Such a belt ply 7 can improve the rigidity of the tread portion 2 in a balanced manner and can reduce the cavity resonance sound of the pneumatic tire 1. Here, the angle of the belt cords is the angle in the pneumatic tire 1 in a normal state, and can be confirmed by, for example, partially peeling off the tread portion 2.

[0035] The tread portion 2 of the present embodiment has a contact surface 2s extending between a pair of tread ends Te. Here, in the pneumatic tire 1 in a normal state under a load state of 70% of the normal load, the tread end Te is the axially outermost contact position of the tire when the tire contacts the flat surface at a camber angle of 0°. The contact surface 2s has a tire tread width TW, which is the distance between the pair of tread ends Te in the tire axial direction. In addition, the central position between the pair of tread ends Te in the tire axial direction is the tire equator C.

[0036] “Normal load” refers to the load specified for each tire in each specification when there is a specification system including the specification to which the pneumatic tire 1 is based, and in the case of JATMA, it refers to the “maximum load capacity”, in the case of TRA, it refers to the maximum value recorded in the table “TIRE LOAD LIMITSAT VARIOUS COLD INFLATION PRESSURES”, and in the case of ETRTO, it refers to “LOAD CAPACITY”. When there is no specification system including the specification to which the pneumatic tire 1 is based, the “Normal load” is the load specified for each tire by the manufacturer, etc., as the maximum load applicable when the pneumatic tire 1 is used.

[0037] The outer end 7e of the belt layer 7 of this embodiment is located axially outward from the tread end Te. Such a belt layer 7 can improve the rigidity of the entire ground contact surface 2s of the tread portion 2 and contribute to reducing the cavity resonance sound of the pneumatic tire 1.

[0038] like Figure 1 and Figure 2 As shown, the plurality of Helmholtz mufflers 9 are preferably arranged separately from each other. The first muffler 9A and the second muffler 9B are, for example, arranged separately in the tire circumferential direction. The plurality of Helmholtz mufflers 9 are preferably provided with the same first muffler 9A or second muffler 9B at a position opposite to the tire axial direction. Such a Helmholtz muffler 9 of the pneumatic tire of the present embodiment can reduce the cavity resonance sound in the entire area of ​​the pneumatic tire 1.

[0039] The multiple Helmholtz mufflers 9 of the present embodiment include multiple first mufflers 9A and multiple second mufflers 9B. It is preferred to set an even number of first mufflers 9A and second mufflers 9B in each row arranged along the tire circumferential direction. This type of Helmholtz muffler 9 is easy to adjust the balance when the tire rotates. In addition, although the multiple Helmholtz mufflers 9 of the present embodiment are illustrated as being arranged in two rows, the multiple Helmholtz mufflers 9 can also be arranged in only one row on one side of the tire axial direction, or in multiple rows in the tire radial direction.

[0040] A pair of first mufflers 9A provided in each row are arranged at positions opposite to each other, for example, sandwiching the tire rotation axis. A pair of second mufflers 9B provided in each row are arranged at positions opposite to each other, for example, sandwiching the tire rotation axis. Such Helmholtz mufflers 9 have excellent balance when the tire rotates, and can suppress vibration and noise generated when the pneumatic tire 1 is running.

[0041] Figure 3 : is a perspective view of the Helmholtz type muffler 9 of this embodiment. Figure 3As shown, the Helmholtz muffler 9 includes a sound absorbing chamber 9a having a space inside and a pipe 9b connecting the sound absorbing chamber 9a and the inner cavity of the tire. By adjusting the volume of the sound absorbing chamber 9a and the length of the pipe 9b, the Helmholtz muffler 9 can have different resonance frequencies f.

[0042] The first muffler 9A of the present embodiment includes a first sound absorbing chamber 9a having a first resonance frequency f1. Although not shown in the figure, the second muffler 9B includes a second sound absorbing chamber 9c having a second resonance frequency f2, for example.

[0043] The first muffler 9A and the second muffler 9B are preferably made of a resin that does not change shape at 120° C. or less. Even when the temperature of the pneumatic tire 1 rises during high-speed running, the Helmholtz muffler 9 does not change shape and can maintain sound absorption performance.

[0044] As the material of the Helmholtz silencer 9, for example, polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyamide (PA), polycarbonate (PC), polyphenylene sulfide (PPS), polyimide (PI), polyetherimide (PEI), polysulfone (PSF), polysulfone (PSU), polytetrafluoroethylene (PTFE), polytrifluorochloroethylene (PCTFE), polyamideimide (PAI), phenolic resin (PF), melamine resin (MF), unsaturated polyester (UP), polyurethane (PU), polydiallyl phthalate (PDAP), silicone resin (SI), epoxy resin (EP), furan formaldehyde resin (FF), cellulose acetate (CA), cellulose nitrate (CN), cellulose propionate (CP), ethyl cellulose (EC), etc.

[0045] Figure 4 2 is a perspective view of a Helmholtz muffler 10 according to the second embodiment. Figure 4 As shown, each of the plurality of Helmholtz mufflers 10 may include, for example, a hemispherical sound absorbing chamber 10a and a pipe portion 10b extending along the sound absorbing chamber 10a. Such a Helmholtz muffler 10 can evenly absorb the cavity resonance sound of the tire cavity by adjusting the direction of the pipe portion 10b.

[0046] Figure 5 3 is a perspective view of the Helmholtz muffler 11 according to the third embodiment. Figure 5As shown, each of the plurality of Helmholtz mufflers 11 may include, for example, at least one first sound absorbing chamber 11a having a first resonance frequency f1, and at least one second sound absorbing chamber 11c having a second resonance frequency f2. Such a Helmholtz muffler 11 may have a plurality of resonance frequencies f in one Helmholtz muffler 11. Therefore, the Helmholtz muffler 11 of the third embodiment can reduce cavity resonance sound with a simple structure.

[0047] It is preferred that the first muffler 11A having the first sound absorbing chamber 11a and the second muffler 11B having the second sound absorbing chamber 11c are formed integrally with each other. Such a Helmholtz muffler 11 can reduce the number of components while reducing the broadband noise.

[0048] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and can be implemented in various modified forms. [Example]

[0049] based on Figure 1 to Figure 3 A pneumatic tire of the embodiment with a tire size of 215 / 55R17 was trial-produced according to the specifications in Table 1. As Comparative Example 1, a pneumatic tire of the same size without a Helmholtz muffler was trial-produced, and as Comparative Example 2, a pneumatic tire with a Helmholtz muffler disposed radially inward of the ground contact surface was trial-produced. The noise performance at different driving speeds was tested using the trial-produced pneumatic tires.

[0050] <Noise Performance> The trial pneumatic tire was installed on the test bench, and the axial force was measured when the tire was running at 20 km / h, 60 km / h and 150 km / h, and the low-frequency side sound pressure and high-frequency side sound pressure of the cavity resonance sound were obtained. The results were expressed as an index with Comparative Example 1 as 100. The smaller the value, the smaller the sound pressure and the better the noise performance.

[0051] The test results are shown in Table 1.

Table 1

[0052] The test results confirmed that the pneumatic tire of the embodiment had excellent noise performance at any running speed compared with the comparative example, and that the cavity resonance sound could be reduced with a simple structure.

[0053] [Notes] The present invention is as follows.

[0054] [Present invention 1] A pneumatic tire, The invention comprises a tread portion, a pair of sidewall portions extending radially inward from both sides of the tread portion in the tire axial direction, a pair of bead portions located radially inward of the pair of sidewall portions, and a plurality of Helmholtz mufflers arranged on the inner cavity surface of the tire. The plurality of Helmholtz mufflers include a first muffler having a first resonance frequency and a second muffler having a second resonance frequency different from the first resonance frequency. The first muffler and the second muffler are respectively arranged on the inner side of at least one of the pair of sidewall portions and the pair of bead portions in the tire axial direction.

[0055] [Present invention 2] According to the pneumatic tire of Invention 1, the first muffler and the second muffler are arranged on the inner side of the pair of bead portions in the tire axial direction.

[0056] [Present invention 3] According to the pneumatic tire of the first or second invention, each of the pair of bead portions has an annular bead core extending in the tire circumferential direction and a bead apex extending from the bead core toward the outside in the tire radial direction. The first muffler and the second muffler are arranged on the inner side in the tire axial direction from the inner end in the tire radial direction of the tire core to the outer end in the tire radial direction of the bead apex.

[0057] [Present invention 4] According to the pneumatic tire of any one of Inventions 1 to 3, the first muffler and the second muffler are made of a resin that does not change shape at 120° C. or lower.

[0058] [Present invention 5] According to the pneumatic tire of any one of Inventions 1 to 4, the first resonance frequency is a maximum resonance frequency in a frequency band. The second resonance frequency is a minimum resonance frequency in the frequency band.

[0059] [Present invention 6] According to the pneumatic tire of the fifth aspect of the present invention, the first resonance frequency is 130 to 350 Hz. The second resonance frequency is 120 to 340 Hz.

[0060] [Present invention 7] In the pneumatic tire according to any one of Inventions 1 to 6, the plurality of Helmholtz mufflers have at least one resonance frequency different from the first resonance frequency and the second resonance frequency.

[0061] [Present invention 8] According to the pneumatic tire of the seventh aspect of the present invention, the unit widths of the plurality of Helmholtz mufflers are substantially equal, and the unit width is a difference between the resonance frequencies of a group of adjacent groups in a frequency band.

[0062] [Present invention 9] According to the pneumatic tire of Invention 8, the unit width is 3 to 10 Hz.

Claims

1. A pneumatic tire, characterized in that: The invention comprises a tread portion, a pair of sidewall portions extending radially inward from both sides of the tread portion in the tire axial direction, a pair of bead portions located radially inward of the pair of sidewall portions, and a plurality of Helmholtz mufflers arranged on the inner cavity surface of the tire. The plurality of Helmholtz mufflers include a first muffler having a first resonance frequency and a second muffler having a second resonance frequency different from the first resonance frequency. The first muffler and the second muffler are respectively arranged on the inner side of at least one of the pair of sidewall portions and the pair of bead portions in the tire axial direction.

2. The pneumatic tire according to claim 1, wherein: The first muffler and the second muffler are arranged on the inner side of the pair of bead portions in the tire axial direction.

3. The pneumatic tire according to claim 1, wherein: Each of the pair of bead portions includes an annular bead core extending in the tire circumferential direction and a bead apex extending from the bead core toward the outer side in the tire radial direction. The first muffler and the second muffler are arranged on the inner side in the tire axial direction from the inner end in the tire radial direction of the tire core to the outer end in the tire radial direction of the bead apex.

4. The pneumatic tire according to claim 1, wherein: The first muffler and the second muffler are made of a resin that does not change shape at 120° C. or lower.

5. The pneumatic tire according to claim 1, wherein: The first resonance frequency is the maximum resonance frequency in the frequency band. The second resonance frequency is a minimum resonance frequency in the frequency band.

6. The pneumatic tire according to claim 5, wherein: The first resonance frequency is 130 to 350 Hz, The second resonance frequency is 120 to 340 Hz.

7. The pneumatic tire according to any one of claims 1 to 6, wherein: The plurality of Helmholtz mufflers have at least one resonance frequency different from the first resonance frequency and the second resonance frequency.

8. The pneumatic tire according to claim 7, wherein: The unit widths of the plurality of Helmholtz mufflers are substantially equal, and the unit width is a difference between the resonance frequencies of a group of adjacent groups in a frequency band.

9. The pneumatic tire according to claim 8, wherein: The unit width is 3 to 10 Hz.

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