JP2024062218A - Pneumatic tires - Google Patents

Abstract

[Problem] To provide a pneumatic tire that can suppress deterioration of uniformity performance while achieving low noise. [Solution] A pneumatic tire 1 has a tread portion 2. A plurality of porous noise-damping bodies 10 are arranged on the tire cavity side of the tread portion 2. The plurality of noise-damping bodies 10 are spaced apart at equal intervals D in the tire circumferential direction. [Selected Figure] Figure 2

Description

The present invention relates to a pneumatic tire.

Conventionally, pneumatic tires have been known in which a porous noise-damping body is arranged on the tire cavity side of the tread portion (see, for example, Patent Document 1).

Japanese Patent No. 6607037

In the pneumatic tire described in Patent Document 1, the circumferential lengths of the multiple air agitation sections are different from each other in order to obtain a good heat diffusion effect at various rotational speeds.

However, the pneumatic tire of Patent Document 1 above may have a weight imbalance in the circumferential direction of the tire, which may result in poor uniformity performance.

The present invention was devised in consideration of the above-mentioned circumstances, and its main objective is to provide a pneumatic tire that can reduce noise while suppressing deterioration of uniformity performance.

The present invention relates to a pneumatic tire having a tread portion,
A plurality of porous noise-damping bodies are disposed on the tire cavity side of the tread portion,
The plurality of noise dampers are spaced at equal intervals in the tire circumferential direction.

The pneumatic tire of the present invention has good uniformity performance because the multiple noise dampers are spaced at equal intervals in the tire circumferential direction. Therefore, it is possible to reduce noise while suppressing deterioration of uniformity performance.

1 is a meridian cross-sectional view of a pneumatic tire of the present invention. FIG. 2 is a diagram showing a cross section of the pneumatic tire of FIG. 1 at the tire equator. FIG. 3 is a diagram showing a cross section at the tire equator of a modified example of the pneumatic tire of FIG. 2 . 3 is a diagram showing a cross section at the tire equator of another modified example of the pneumatic tire of FIG. 2. FIG. 3 is a diagram showing a cross section at the tire equator of still another modified example of the pneumatic tire of FIG. 2. FIG. 3 is a diagram showing a cross section at the tire equator of still another modified example of the pneumatic tire of FIG. 2. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a meridian cross-sectional view including a tire axis of a pneumatic tire 1 according to the present embodiment.

The pneumatic tire 1 has a tread portion 2. The tread portion 2 is continuous around the tire circumference and is formed in an annular shape.

The pneumatic tire 1 further includes a pair of sidewall portions 3 and a pair of bead portions 4.

In the pneumatic tire 1 of this embodiment, a bead core 5 is embedded in each of the pair of bead portions 4. Furthermore, a carcass ply 6 extends between the pair of bead portions 4 so as to straddle the pair of bead cores 5. In addition, a belt ply 7 is disposed on the radially outer side of the carcass ply 6.

A noise-damping body 10 is disposed on the tire inner cavity side of the tread portion 2. The noise-damping body 10 is made of, for example, a porous sponge material.

The sponge material is a sponge-like porous structure, and includes, for example, the so-called sponge itself, which has open cells made by foaming rubber or synthetic resin, as well as web-like structures made by intertwining and connecting animal fibers, plant fibers, synthetic fibers, etc. together. Furthermore, the term "porous structure" includes those with not only open cells but also closed cells. The sound damper 10 in this example uses an open-cell sponge material made of foamed polyurethane.

The sponge material described above converts the vibration energy of the vibrating air in the porous parts on the surface or inside into heat energy and consumes it, thereby reducing sound (cavity resonance energy) and reducing the running noise of the pneumatic tire 1. In addition, since the sponge material is easily deformed by shrinking, bending, etc., it does not substantially affect the deformation of the tire during running. This makes it possible to prevent a deterioration in steering stability.

As the sponge material, synthetic resin sponges such as ether-based polyurethane sponge, ester-based polyurethane sponge, polyethylene sponge, and rubber sponges such as chloroprene rubber sponge (CR sponge), ethylene propylene rubber sponge (EDPM sponge), and nitrile rubber sponge (NBR sponge) can be preferably used, and in particular, polyurethane-based or polyethylene-based sponges including ether-based polyurethane sponge are preferred from the standpoints of sound-damping properties, light weight, foaming adjustability, durability, etc.

Figure 2 shows a cross section of a pneumatic tire 1 at the tire equator. In the pneumatic tire 1 of this embodiment, multiple noise-damping bodies 10 are arranged on the tire cavity side of the tread portion 2. The multiple noise-damping bodies 10 are spaced apart at equal intervals D in the tire circumferential direction.

Here, "equal spacing D" allows for manufacturing errors in the pneumatic tire 1, and does not require strict equality. For example, taking into account the effect on the uniformity performance of the noise damper 10, a range of ±30 mm with respect to spacing D may be considered to be "equal spacing D."

Although the specific gravity of the sponge material is small, it does have a significant effect on the weight balance of the pneumatic tire 1. Therefore, in the pneumatic tire described in Patent Document 1 above, in which multiple noise-damping bodies 10 are arranged at different intervals D, there is a risk of the uniformity performance being deteriorated.

However, in the pneumatic tire 1 of this embodiment, the multiple noise-damping bodies 10 are spaced at equal intervals D in the tire circumferential direction, so good uniformity performance is obtained. Therefore, it is possible to achieve low noise while suppressing deterioration of uniformity performance.

In the pneumatic tire 1, the cross-sectional area S1 of the multiple noise-damping bodies 10 in a meridian section including the tire axis is preferably 8 to 20% of the cross-sectional area S2 of the tire cavity 100 in a meridian section including the tire axis. Note that the above cross-sectional areas S1 and S2 are measured in a "normal state" in which the pneumatic tire 1 is mounted on a normal rim and inflated to a normal internal pressure.

"Genuine rim" refers to a rim that is determined for each tire by the standard system that includes the standard on which the tire is based. For example, JATMA calls it a "standard rim," TRA calls it a "design rim," and ETRTO calls it a "measuring rim."

"Normal internal pressure" is the air pressure set for each tire by the standards on which the tire is based, including the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO. If the tire is for passenger cars, the normal internal pressure is, for example, 180 kPa.

The cross-sectional area S1 of the noise damper 10 refers to the apparent cross-sectional area of the noise damper 10, which is determined from the outer shape including the air bubbles inside.

When the cross-sectional area S1 is 8% or more of the cross-sectional area S2, the cavity resonance reduction effect is excellent. On the other hand, when the cross-sectional area S1 exceeds 20% of the cross-sectional area S2, the above-mentioned cavity resonance reduction effect is saturated. In this embodiment, the cross-sectional area S1 is 20% or less of the cross-sectional area S2, so that a sufficient cavity resonance reduction effect is obtained, while the weight of the noise damper 10 is reduced and the impact on uniformity performance due to the provision of the noise damper 10 in the tread portion 2 is suppressed.

It is preferable that the number of multiple sound-damping bodies 10 is two. This provides a good effect in reducing cavity resonance. The noise-damping body 10 has fewer ends where stress is concentrated, improving the durability of the noise-damping body 10.

It is desirable for the distance D between the multiple sound-damping bodies 10 to be 100 mm or less. This provides good uniformity performance. It also provides a good effect in reducing cavity resonance.

Figure 3 is a cross-sectional view of a pneumatic tire 1A, which is a modified example of the pneumatic tire 1 in Figure 2. The configuration of the pneumatic tire 1 described above can be adopted for the parts of the pneumatic tire 1A that are not described below.

As shown in FIG. 3, it is preferable that the circumferential ends of the multiple noise dampers 10 have tapered sections 11 in which the thickness in the radial direction of the tire decreases toward the edge. The tapered sections 11 chamfer the circumferential ends of the noise dampers 10. This reduces stress concentration at the ends, improving the durability of the noise dampers 10. The tapered sections 11 are formed so that the length in the circumferential direction of the tire increases toward the outer side in the radial direction of the tire. This increases the adhesion area of the noise dampers 10, and prevents the noise dampers 10 from peeling off.

As with the tapered portion 11, tapered portions may be formed at the axial ends of the multiple noise dampers 10, with the thickness decreasing in the radial direction of the tire toward the edge. As with the tapered portion 11, it is also preferable that the axial ends of the tire are formed such that the axial length increases toward the radially outward side of the tire. This reduces stress concentration at the ends, improving the durability of the noise dampers 10.

As shown in FIG. 2, it is desirable for the lengths L of the multiple noise dampers 10 in the tire circumferential direction to be the same. This allows for good uniformity performance.

Here, "the length L is the same" allows for manufacturing errors in the pneumatic tire 1, and does not require exact sameness. For example, taking into account the effect on the uniformity performance of the sound damper 10, a range of ±30 mm with respect to the length L may be considered to be "the same length L".

Figure 4 is a cross-sectional view of a pneumatic tire 1B, which is a further modified example of the pneumatic tire 1 in Figure 2. For parts of the pneumatic tire 1B that are not described below, the configuration of the pneumatic tire 1 or 1A described above can be adopted.

As shown in FIG. 4, in a pneumatic tire 1B, a sealant layer 20 containing a viscous sealant is formed on the tire cavity side of the tread portion 2. The sealant layer 20 is formed continuously in the tire circumferential direction.

The sealant layer 20 contains a viscous sealant 20a. The viscous sealant 20a is not particularly limited as long as it has adhesiveness, and for example, a typical rubber composition used for sealing punctures in tires can be used. As the rubber component constituting the main component of the rubber composition, for example, a butyl-based rubber is used. Examples of butyl-based rubber include butyl rubber (I I R ) and halogenated butyl rubber (X-I I R ) such as brominated butyl rubber (B r-I I R ) and chlorinated butyl rubber (C l-I I R ). Among them, from the viewpoint of fluidity, either butyl rubber or halogenated butyl rubber, or both, can be preferably used.

The liquid polymer in the viscous sealant 20a may be liquid polybutene, liquid polyisobutene, liquid polyisoprene, liquid polybutadiene, liquid poly-α-olefin, liquid isobutylene, liquid ethylene-α-olefin copolymer, liquid ethylene-propylene copolymer, liquid ethylene-butylene copolymer, etc. Among them, liquid polybutene is preferred from the viewpoint of imparting adhesiveness, etc. Examples of liquid polybutene include copolymers with a molecular structure of long-chain hydrocarbons that are mainly composed of isobutene and further reacted with normal butene, and hydrogenated liquid polybutene can also be used.

The curing agent (crosslinking agent) is not particularly limited and any conventionally known compound can be used, but organic peroxides are preferred. In an organic peroxide crosslinking system, the use of butyl rubber or liquid polymer improves adhesion, sealing properties, fluidity, and processability.

The content of the organic peroxide (crosslinking agent) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. If it is less than 0.5 parts by mass, the crosslink density will be low and there is a risk of the viscous sealant flowing. The content is preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. If it exceeds 40 parts by mass, the crosslink density will be high, the viscous sealant 20a will harden, and there is a risk of the sealability being reduced.

The viscous sealant 20a may contain an inorganic additive selected from the group consisting of carbon black, silica, calcium carbonate, calcium silicate, magnesium oxide, aluminum oxide, barium sulfate, talc, mica, and mixtures thereof.

The viscous sealant 20a preferably contains, for example, 100 parts by mass of butyl rubber, 100 to 400 parts by mass of polybutene, 1 to 15 parts by mass of a cross-linking agent, and 1 to 15 parts by mass of a cross-linking assistant. The average molecular weight of the polybutene is preferably, for example, 1,000 to 4,000.

As shown in FIG. 4, multiple noise-damping bodies 10 are arranged on the radially inner side of the sealant layer 20. This makes it possible to reduce cavity resonance while achieving good puncture sealing effects.

The hardness of the multiple sound dampers 10 measured in accordance with JIS K6400-2 D method in an atmosphere of 23°C is preferably 60 to 170 N. Sound dampers 10 with the above hardness of 60 to 170 N have excellent durability against shear strain.

In an atmosphere of 23°C, the tensile strength of the multiple sound dampers 10 measured in accordance with JIS K6400-5 is preferably 60 to 180 kPa. Sound dampers 10 with the above hardness of 60 to 180 kPa have excellent durability against shear strain.

The multiple noise dampers 10 are adhered to the tread portion 2 via an adhesive layer, and it is desirable that the peel adhesion strength of the adhesive layer measured in accordance with JIS Z0237 is 8N/20mm to 40N/20mm. This makes it possible to easily attach the noise dampers 10 and dismantle them when disposing of the tire while maintaining good fixing strength of the noise dampers 10.

Figure 5 is a cross-sectional view of a pneumatic tire 1C, which is yet another modified example of the pneumatic tire 1 in Figure 2. For parts of the pneumatic tire 1C that are not described below, the configurations of the pneumatic tires 1 to 1B described above can be adopted.

As shown in FIG. 5, in a pneumatic tire 1C, an electronic device 30 may be provided between multiple noise dampers 10 adjacent in the tire circumferential direction. One example of the electronic device 30 is a tire pressure monitoring system (TPMS) for detecting tire air pressure. Another example of the electronic device 30 is a transponder such as an RFID (Radio Frequency Identification) tag. The electronic device 30 is fixed to the inner cavity surface of the pneumatic tire C, for example, via an adhesive or the like.

By disposing the electronic device 30 between multiple noise-damping bodies 10 that are adjacent in the tire circumferential direction, the weight imbalance of the pneumatic tire 1C is corrected, improving uniformity performance.

Figure 6 is a cross-sectional view of a pneumatic tire 1D, which is yet another modified example of the pneumatic tire 1 in Figure 2. For parts of the pneumatic tire 1D that are not described below, the configurations of the pneumatic tires 1 to 1C described above can be adopted.

The tread portion 2 of the pneumatic tire 1D is provided with a tread rubber 2G having a joint 2J in at least a portion of the tire circumferential direction. At the joint 2J, both ends of the strip-shaped tread rubber 2G are overlapped. Therefore, the joint 2J tends to be heavier than other areas of the tread rubber 2G.

Therefore, it is desirable that the multiple noise dampers 10 are separated at the joints 2J of the tread rubber 2G. This corrects the weight imbalance of the pneumatic tire 1D and improves uniformity performance.

Note that "the multiple noise-damping bodies 10 are separated by the joints 2J of the tread rubber 2G" means that the joints 2J of the tread rubber 2G and the discontinuous regions of the multiple noise-damping bodies 10 overlap at least in part in the tire circumferential direction.

A belt ply 7 having a joint (not shown) in at least a portion of the tire circumferential direction is disposed in the tread portion 2 of the pneumatic tire 1D. At the joint, both ends of the belt-shaped belt ply 7 are overlapped. Therefore, the joint tends to be heavier than other areas of the belt ply 7.

Therefore, the multiple noise dampers 10 may be separated at the joints of the belt plies 7. This corrects the weight imbalance of the pneumatic tire 1D and improves uniformity performance.

Note that "the multiple noise-damping bodies 10 are separated by the joints of the belt ply 7" means that the joints of the belt ply 7 and the discontinuous regions of the multiple noise-damping bodies 10 overlap at least in part in the tire circumferential direction.

A carcass ply 6 having a joint (not shown) in at least a portion of the tire circumferential direction is arranged in the tread portion 2 of the pneumatic tire 1D. At the joint, both ends of the strip-shaped carcass ply 6 are overlapped. Therefore, the joint tends to be heavier than other areas of the carcass ply 6.

Therefore, the multiple noise dampers 10 may be separated at the joints of the carcass ply 6. This corrects the weight imbalance of the pneumatic tire 1D and improves uniformity performance.

Note that "the multiple noise-damping bodies 10 are separated by the joints of the carcass ply 6" means that the joints of the carcass ply 6 and the discontinuous areas of the multiple noise-damping bodies 10 overlap at least in part in the tire circumferential direction.

In the tread portion 2 of the pneumatic tire 1D, an inner liner 9 (see FIG. 1) is disposed radially inward of the carcass ply 6 and has a joint (not shown) at least in a portion of the tire circumferential direction. The inner liner 9 includes a layer made of an air-impermeable rubber material. At the joint, both ends of the strip-shaped inner liner 9 are overlapped. Therefore, the joint tends to be heavier than other areas of the inner liner 9.

Therefore, the multiple noise dampers 10 may be separated at the joints of the inner liner 9. This corrects the weight imbalance of the pneumatic tire 1D and improves uniformity performance.

Note that "the multiple noise-damping bodies 10 are separated by the joints of the inner liner 9" means that the joints of the inner liner 9 and the discontinuous regions of the multiple noise-damping bodies 10 overlap at least in part in the tire circumferential direction.

The pneumatic tire 1 of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment described above and can be modified and implemented in various forms.

A pneumatic tire of size 215/55R17 having the basic structure shown in FIG. 1 was prototyped based on the specifications in Table 1, and the noise performance and uniformity performance were tested. The common specifications of the sound damper are as follows.
Specific gravity: 30 kg/ ^m3
Material: Ether-based polyurethane Width: 100mm
Thickness: 20mm
In Tables 1 and 3, the number of noise dampers is 2, the interval between one of the noise dampers is D1 and the interval between the other is D2, and in Tables 1 and 4, the circumferential length of one of the noise dampers is L1 and the circumferential length of the other noise damper is L2. The test method is as follows.

<Noise performance>
Each test tire, assembled on a rim of size 7J×17 and inflated to an internal pressure of 220 kPa, was loaded with a test load of 4.2 kN on a drum of diameter 1550 mm on which a simulated road surface was formed. Furthermore, each test tire was run at a speed of 60 km/h, and the peak value of the cavity resonance sound near 220 Hz was measured. The results are expressed as an index with Comparative Example 1 being 100, and the higher the value, the better the noise performance.

<Uniformity performance>
Each of the above sample tires was run at a speed of 120 km/h, and the presence or absence of vibration was evaluated by a tester. The results are expressed as a score based on Comparative Example 1 being 100, and the higher the score, the more excellent the uniformity performance.

As is clear from Table 1, it was confirmed that the pneumatic tires of the examples were able to significantly suppress deterioration in uniformity performance while achieving low noise compared to the comparative examples.

A pneumatic tire of size 215/55R17 having the basic structure of Fig. 1 was prototyped based on the specifications in Table 2, and the noise performance and uniformity performance were tested in the same manner as above. The cross-sectional area S1 of the sound damper was adjusted by changing its thickness. The results were compared with Example 4 being set at 100, and the larger the value, the better the noise performance and uniformity performance.

A pneumatic tire having the basic structure shown in FIG. 1 and a size of 215/55R17 was prototyped based on the specifications in Table 3, and the noise performance was tested in the same manner as above. The results were compared with Example 8 being set at 100, with a larger value indicating better noise performance.

A pneumatic tire having the basic structure of Fig. 1 and a size of 215/55R17 was prototyped based on the specifications in Table 4, and the uniformity performance was tested in the same manner as above. The results were compared with Example 11 being set at 100, with a larger value indicating better uniformity performance.

A pneumatic tire of size 215/55R17 having the basic structure shown in Figure 1 was prototyped based on the specifications in Table 5, and its durability performance was tested. The test method was as follows.

<Durability>
Each test tire, assembled on a rim of size 7J×17 and inflated to an internal pressure of 220 kPa, was loaded with a test load of 6.0 kN on a drum of diameter 1700 mm. Furthermore, each test tire was run at a speed of 120 km/h, and the running distance until the sound damper was broken was measured. The results were compared with Example 12 being set at 100, and the higher the value, the better the durability performance.

[Additional Notes]
The present invention includes the following aspects.

[Invention 1]
A pneumatic tire having a tread portion,
A plurality of porous noise-damping bodies are disposed on the tire cavity side of the tread portion,
The plurality of noise dampers are spaced at equal intervals in the tire circumferential direction.
Pneumatic tires.
[Invention 2]
The pneumatic tire according to the first aspect of the present invention, wherein a cross-sectional area of the plurality of noise dampers in a meridian section including the tire axis is 8 to 20% of a cross-sectional area of the tire cavity in a meridian section including the tire axis.
[The present invention 3]
3. The pneumatic tire according to claim 1 or 2, wherein the number of the plurality of noise dampers is two.
[Invention 4]
4. The pneumatic tire according to any one of claims 1 to 3, wherein the intervals between the plurality of noise dampers are 100 mm or less.
[Invention 5]
The pneumatic tire according to any one of claims 1 to 4, wherein end portions in the tire circumferential direction or the tire axial direction of the plurality of noise dampers have tapered portions in which the thickness in the tire radial direction decreases toward the end edges.
[Invention 6]
The pneumatic tire according to any one of claims 1 to 5, wherein the plurality of sound bodies have the same length in the tire circumferential direction.
[Invention 7]
The pneumatic tire according to any one of claims 1 to 6, wherein a sealant layer containing a viscous sealant is continuously formed in a circumferential direction of the tire on the tire cavity side of the tread portion, and the plurality of noise-damping bodies are arranged on the radially inward side of the sealant layer.
[The present invention 8]
The pneumatic tire according to any one of claims 1 to 7, wherein the hardness of the plurality of noise dampers measured in an atmosphere at 23°C in accordance with JIS K6400-2 D method is 60 to 170 N.
[The present invention 9]
The pneumatic tire according to any one of claims 1 to 8, wherein the plurality of noise dampers have a tensile strength of 60 to 180 kPa as measured in an atmosphere at 23°C in accordance with JIS K6400-5.
[The present invention 10]
The pneumatic tire according to any one of claims 1 to 9, wherein the plurality of noise dampers are adhered to the tread portion via an adhesive layer, and a peel adhesion strength of the adhesive layer measured in accordance with JIS Z0237 is 8 N/20 mm to 40 N/20 mm.
[Invention 11]
The pneumatic tire according to any one of claims 1 to 10, wherein an electronic device is provided between the plurality of noise damping bodies adjacent to each other in the tire circumferential direction.
[Invention 12]
12. The pneumatic tire according to any one of claims 1 to 11, wherein the plurality of noise dampers have open cells.
[The present invention 13]
13. The pneumatic tire according to claim 12, wherein the plurality of noise dampers are made of polyurethane foam.
[The present invention 14]
A tread rubber having a joint at least in a part in a circumferential direction of the tire is disposed in the tread portion,
14. The pneumatic tire according to any one of claims 1 to 13, wherein the plurality of noise dampers are separated by joints of the tread rubber.
[The present invention 15]
A belt ply having a joint at least in a part in a tire circumferential direction is disposed in the tread portion,
15. The pneumatic tire according to any one of claims 1 to 14, wherein the plurality of noise dampers are separated at joints of the belt plies.
[The present invention 16]
A carcass ply having a joint at least in a part in a tire circumferential direction is disposed in the tread portion,
16. The pneumatic tire according to any one of claims 1 to 15, wherein the plurality of noise damping bodies are separated at joints of the carcass ply.
[The present invention 17]
An inner liner having a joint at least in a portion in a circumferential direction of the tire is disposed in the tread portion,
2. The pneumatic tire according to claim 1, wherein the plurality of noise dampers are separated at joints of the inner liner.

Reference Signs List 1: Tire 1: Pneumatic tire 1A: Pneumatic tire 1B: Pneumatic tire 1C: Pneumatic tire 1D: Pneumatic tire 2: Tread portion 2G: Tread rubber 2J: Joint 6: Carcass ply 7: Belt ply 9: Inner liner 10: Noise-damping body 11: Tapered portion 20: Sealant layer 20a: Viscous sealant 30: Electronic device 100: Tire cavity C: Pneumatic tire S1: Cross-sectional area S2: Cross-sectional area

Claims (17)

A pneumatic tire having a tread portion,
A plurality of porous noise-damping bodies are disposed on the tire cavity side of the tread portion,
The plurality of noise dampers are spaced at equal intervals in the tire circumferential direction.
Pneumatic tires. The pneumatic tire according to claim 1, wherein the cross-sectional area of the multiple noise dampers in a meridian section including the tire axis is 8 to 20% of the cross-sectional area of the tire cavity in a meridian section including the tire axis. The pneumatic tire according to claim 1, wherein the number of the plurality of sound-damping bodies is two. The pneumatic tire according to claim 1, wherein the spacing between the multiple noise dampers is 100 mm or less. The pneumatic tire according to claim 1, wherein the ends of the plurality of noise dampers in the tire circumferential direction or the tire axial direction have tapered portions in which the thickness in the tire radial direction decreases toward the end edges. The pneumatic tire according to claim 1, wherein the length of each of the plurality of sound bodies in the tire circumferential direction is the same. The pneumatic tire according to claim 1, wherein a sealant layer containing a viscous sealant is formed continuously in the tire circumferential direction on the tire inner cavity side of the tread portion, and the plurality of noise-damping bodies are arranged on the tire radially inward side of the sealant layer. The pneumatic tire according to claim 1, wherein the hardness of the multiple sound-damping bodies measured in an atmosphere of 23°C according to JIS K6400-2 D method is 60 to 170 N. The pneumatic tire according to claim 1, wherein the tensile strength of the multiple noise dampers measured in accordance with JIS K6400-5 in an atmosphere of 23°C is 60 to 180 kPa. The pneumatic tire according to claim 1, wherein the plurality of noise dampers are adhered to the tread portion via an adhesive layer, and the peel adhesion strength of the adhesive layer measured in accordance with JIS Z0237 is 8N/20mm to 40N/20mm. The pneumatic tire according to claim 1, wherein an electronic device is provided between the plurality of noise dampers adjacent in the tire circumferential direction. The pneumatic tire according to claim 1, wherein the plurality of sound-damping bodies have open cells. The pneumatic tire according to claim 12, wherein the plurality of sound-damping bodies are made of polyurethane foam. A tread rubber having a joint at least in a part in a circumferential direction of the tire is disposed in the tread portion,
The pneumatic tire according to claim 1 , wherein the plurality of noise dampers are separated at joints of the tread rubber. A belt ply having a joint at least in a part in a tire circumferential direction is disposed in the tread portion,
The pneumatic tire of claim 1 , wherein the plurality of noise damping elements are separated at joints of the belt plies. A carcass ply having a joint at least in a part in a tire circumferential direction is disposed in the tread portion,
The pneumatic tire of claim 1 , wherein the plurality of sound damping elements are spaced apart at joints of the carcass plies. An inner liner having a joint at least in a portion in a circumferential direction of the tire is disposed in the tread portion,
The pneumatic tire of claim 1 , wherein the plurality of sound damping elements are separated at joints of the innerliner.

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