Pneumatic tire and noise damper

Abstract

To provide a pneumatic tire capable of suppressing a deterioration in puncture repairability with a puncture repair kit while suppressing road noise and the like.SOLUTION: The present invention provides a pneumatic tire allowing a puncture to be repaired by injecting a puncture-sealing agent. The pneumatic tire includes: a pneumatic tire body 1A defining a tire inner cavity 1B; and a noise damper 10 disposed in the tire inner cavity 1B. The noise damper 10 includes: a first porous layer 11 disposed on an inner cavity surface side of a tread part 2 of the pneumatic tire body 1A; and a second porous layer 12 disposed on a tire radial direction inner side of the first porous layer 11. Permeability of the first porous layer 11 is greater than permeability of the second porous layer 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pneumatic tire and a sound deadening body.

Background Art

[0002] Patent Document 1 below proposes a pneumatic tire in which a porous sound deadening body is fixed to the inner surface of the tread portion. This pneumatic tire can suppress road noise and the like by the sound deadening body.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, a puncture repair kit that can inject a puncture sealant into the tire inner cavity when a pneumatic tire is punctured to close the puncture hole has become popular. Also, in vehicles, the number of vehicles equipped with the puncture repair kit instead of a spare tire is increasing.

[0005] However, when repairing a pneumatic tire equipped with the above-described sound deadening body with a puncture repair kit, the sound deadening body may interfere with the flow of the puncture sealant into the puncture hole in the tread portion, increasing the time until the puncture hole is closed, and thus deteriorating the puncture reparability.

[0006]

Means for Solving the Problems

[0007] ​The present invention relates to a pneumatic tire capable of repairing a puncture by injecting a puncture sealant, including a pneumatic tire body that defines a tire inner cavity and a sound deadening body disposed in the tire inner cavity. The sound deadening body includes a first porous layer disposed on the inner cavity surface side of the tread portion of the pneumatic tire body and a second porous layer disposed on the inner side in the tire radial direction of the first porous layer. The air permeability of the first porous layer is greater than that of the second porous layer.

Advantages of the Invention

[0008] By adopting the above configuration, the pneumatic tire of the present invention can suppress road noise and the like, and can also suppress the deterioration of puncture reparability with a puncture repair kit.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Although the drawings describe the features of the present invention, in order to assist in understanding the present invention, there may be exaggerated expressions or expressions different from the actual structural dimensional ratios. Also, throughout each embodiment, the same or common elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

[0011] FIG. 1 is a tire meridian cross-sectional view showing a pneumatic tire (hereinafter sometimes simply referred to as "tire") 1 in a normal state according to an embodiment of the present invention. Note that FIG. 1 shows a cross-section of the tire 1 when the tire 1 extending in an annular shape is cut by a virtual plane passing through the tire rotation axis and orthogonal to the tire circumferential direction. As shown in FIG. 1, the present embodiment is a pneumatic tire 1 for a passenger car. However, the present invention may be applied to, for example, a pneumatic tire 1 for heavy loads.

[0012] The "normal state" means that in the case of a pneumatic tire with various standards defined, the tire is rim-mounted on a normal rim and filled with a normal internal pressure, and moreover, it is in a no-load state. In the case of a tire without various defined standards, the normal state means a standard usage state according to the usage purpose of the tire, which means a state where the tire is not mounted on a vehicle and is in a no-load state. In this specification, unless otherwise specified, the dimensions etc. of each part of the tire are values measured in the normal state.

[0013] The "normal rim" is the rim defined for each tire in a standard system including the standards on which the tire is based. For example, in JATMA, it is the "standard rim", in TRA, it is the "Design Rim", and in ETRTO, it is the "Measuring Rim".

[0014] The "normal internal pressure" is the air pressure defined for each tire in a standard system including the standards on which the tire is based. In JATMA, it is the "maximum air pressure", in TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in ETRTO, it is the "INFLATION PRESSURE".

[0015] The tire 1 of the present embodiment is a pneumatic tire that can be repaired by injecting a puncture sealant. Therefore, the tire 1 of the present embodiment can be mounted on a vehicle equipped with a puncture repair kit including the puncture sealant. FIG. 2 shows a conceptual diagram of the puncture repair kit 20. In FIG. 2, the puncture repair kit 20 is drawn enlarged compared to the actual size of the tire 1. This puncture repair kit 20 includes a bottle unit 21 containing the puncture sealant and a compressor 22 capable of supplying high-pressure air. The bottle unit 21 is preferably attached to the compressor 22 and used. The puncture repair kit 20 performs puncture repair by injecting the puncture sealant from the air valve of the punctured tire. The puncture sealant injected into the tire interior can harden when passing through the puncture hole and block it.

[0016] Therefore, as shown in FIG. 1, the tire 1 of the present embodiment has such rigidity in the tread portion 2 that the blocked puncture hole does not open again even when driving after puncture repair. Specifically, it includes at least the carcass 6 and the belt layer 7 described below.

[0017] The carcass 6 extends from the bead portion 4 on one side, through the sidewall portion 3 on one side, the tread portion 2, and the sidewall portion 3 on the other side, to the bead portion 4 on the other side. Further, the carcass 6 has at least one, in this embodiment, two carcass plies 6A. The carcass ply 6A is formed, for example, by covering an array of carcass cords with topping rubber. The carcass cords are arranged, for example, at an angle of 75 to 90° with respect to the tire circumferential direction. Organic fibers such as polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers are applied to the carcass cords.

[0018] The carcass ply 6A includes, for example, a body portion 6a and a folded-back portion 6b. The body portion extends from the tread portion 2 through the sidewall portion 3 to the bead core 5. The folded-back portion 6b is continuous with the body portion 6a, is folded back from the inner side to the outer side in the tire axial direction around the bead core 5, and extends outward in the tire radial direction.

[0019] The belt layer 7 is disposed on the outer side in the tire radial direction of the carcass 6 in the tread portion 2. The belt layer 7 includes at least one belt ply, and the belt layer 7 of the present embodiment is composed of two belt plies 7A and 7B. The belt plies 7A and 7B are formed, for example, by covering an array of belt cords with topping rubber.

[0020] The tire 1 of the present invention includes a pneumatic tire body 1A that defines a tire inner cavity 1B and a sound deadening body 10 disposed in the tire inner cavity 1B. This sound deadening body 10 can absorb the vibration of air inside the tire 1 during running and can suppress load noise and the like generated by the tire.

[0021] On the other hand, conventionally, when repairing a pneumatic tire equipped with a sound deadening body with a puncture repair kit, the sound deadening body may prevent the puncture sealant from flowing into the puncture hole in the tread portion, increasing the time until the puncture hole is closed, etc., and the puncture repairability may deteriorate.

[0022] FIG. 3 shows an enlarged cross-sectional view of the sound deadening body 10. FIG. 4 shows a partially enlarged perspective view conceptually showing the state of the outer surface of the sound deadening body 10. As shown in FIGS. 3 and 4, in the present invention, the sound deadening body 10 includes a first porous layer 11 disposed on the inner cavity surface side of the tread portion 2 (shown in FIG. 1) of the pneumatic tire body 1A, and a second porous layer 12 disposed on the inner side in the tire radial direction of the first porous layer 11. Further, the air permeability of the first porous layer 11 is greater than the air permeability of the second porous layer 12.

[0023] As a result, in the tire 1 of the present invention, when repairing a puncture with the above-described puncture repair kit, the puncture sealant can easily pass through the first porous layer 11 and reach the puncture hole, and problems such as an increase in the time until the puncture sealant closes the puncture hole can be prevented. Therefore, the tire 1 of the present invention can suppress deterioration of puncture reparability with the puncture repair kit while suppressing road noise and the like by the sound control body 10.

[0024] Hereinafter, a more detailed configuration of the present embodiment will be described. Each configuration described below shows a specific aspect of the present embodiment. Therefore, it goes without saying that the present invention can exhibit the above-described effects even if it does not have the configurations described below. Further, even if any one of the configurations described below is applied alone to the tire of the present invention having the above-described features, an improvement in performance corresponding to each configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a combined improvement in performance corresponding to each configuration can be expected.

[0025] Note that the dimensions of the sound control body 10 described below are measured in a state where the tire 1 is not mounted on the rim, the distance between the pair of bead cores 5 is made to coincide with the above-described normal state, and the sound control body 10 is disposed in the tire inner cavity 1B.

[0026] As shown in FIG. 1, the sound control body 10 has, for example, a horizontally long rectangular cross section in the tire axial direction and extends continuously in the tire circumferential direction. Further, the sound control body 10 is entirely configured as a porous sponge material, and in the present embodiment, it is composed of only the first porous layer 11 and the second porous layer 12. However, the sound control body 10 may include a layer different from the first porous layer 11 and the second porous layer 12. As the sponge material, for example, a material having continuous air bubbles obtained by foaming rubber or synthetic resin is adopted.

[0027] The average density of the sound control body 10 is, for example, 5 to 60 kg / m 3 and preferably 20 to 40 kg / m 3It is also the case that the first porous layer 11 and the second porous layer 12 each have a cellular structure in which an ether structure and an ester bond are mixed. Such a soundproofing body 10 has excellent durability and can exhibit high sound absorption performance.

[0028] The cross-sectional area of the soundproofing body 10 is desirably 3% to 20% of the total cross-sectional area of the pneumatic tire body 1A and the tire inner cavity 1B. Thereby, while suppressing an excessive increase in tire weight, excellent noise performance can be exhibited. The total cross-sectional area means the area of the region surrounded by the virtual line 15 connecting the inner ends in the tire radial direction of the two bead portions 4 and the inner cavity surface 1Bs defining the tire inner cavity 1B.

[0029] As shown in FIG. 3, the average thickness ta of the soundproofing body 10 is, for example, 25 to 35 mm. The length L1 of the soundproofing body 10 in the tire axial direction is, for example, 50 to 150 mm. The average thickness ta is measured in a virtual state in which all the fine cells included in the porous soundproofing body 10 are filled, and corresponds to the cross-sectional area of the soundproofing body 10 divided by its length L1 in the tire axial direction. The same applies to the thicknesses of the first porous layer 11 and the second porous layer 12 described later.

[0030] The air permeability of the first porous layer 11 and the second porous layer 12 is specified by the magnitude of the air volume measured according to JIS K6400-7. That is, in the present invention, the air volume of the first porous layer 11 is larger than the air volume of the second porous layer 12.

[0031] The air volume V1 of the first porous layer 11 measured according to JIS K6400-7 is, for example, 62 ml / cm 2 / s or more. From the viewpoint of more surely suppressing the deterioration of puncture reparability, the air volume V1 is more desirably 100 ml / cm 2 / s or more, and even more desirably 200 ml / cm 2 / s or more. However, when the ventilation volume V1 is excessively increased, while the permeability of the puncture sealant saturates, the durability of the first porous layer 11 may be impaired. From this perspective, the ventilation volume V1 is, for example, 300 ml / cm 2 / s or less, desirably 250 ml / cm 2 / s or less, more desirably 220 ml / cm 2 / s or less.

[0032] When the tire 1 is in use, the first porous layer 11 tends to be compressed outward in the tire radial direction. Even in this case, from the perspective of fully exerting the above-described effects, the hardness H1 at 25% compression load measured in accordance with JIS K6400-2 D method of the first porous layer 11 is, for example, 1.1 kPa or more, desirably 1.9 kPa or more, more desirably 2.9 kPa or more. However, if the hardness H1 is excessively large, there is a risk of causing other problems such as an increase in tire weight. From this perspective, it is desirable that the hardness H1 is 3.5 kPa or less.

[0033] The number of cells N1 (pieces / 25 mm) of the first porous layer 11 is, for example, 30 ± 4 or less, desirably 20 ± 4 or less, more desirably 8 ± 2 or less. The number of cells is measured in accordance with JIS-K6400. Also, the average thickness t1 of the first porous layer 11 is, for example, 2 to 10 mm. By providing the above-described number of cells N1 and thickness t1, the first porous layer 11 alone is configured as a sponge material having a roughness such that visible light can be transmitted (that is, the opposite side can be seen through).

[0034] As shown in FIG. 1, the sound insulation body 10 has a contact surface 10s with the pneumatic tire body 1A, and at least 30% or more, desirably 60% or more, more desirably 80% or more of this contact surface 10s is formed of the first porous layer 11. As a more desirable embodiment, in the present embodiment, the entire contact surface 10s is formed of the first porous layer 11. Thereby, the deterioration of the puncture reparability can be more reliably suppressed.

[0035] As shown in Fig. 3, the first porous layer 11 is fixed to the second porous layer 12. The first porous layer 11 and the second porous layer 12 may be adhered by an adhesive, or may be welded by heat (adhering after melting the sponge material with heat) without using an adhesive.

[0036] From the viewpoint of enabling the second porous layer 12 to exhibit sound absorption performance, the air permeability V2 of the second porous layer 12 measured in accordance with JIS K6400-7 is, for example, less than 100 ml / cm 2 / s, desirably less than 80 ml / cm 2 / s, more desirably less than 70 ml / cm 2 / s, even more desirably less than 62 ml / cm 2 / s. Also, if the air permeability V2 is excessively small, the second porous layer 12 may reflect sound waves and impair the sound absorption performance. From this viewpoint, the air permeability V2 is, for example, 2 ml / cm 2 / s or more, desirably 5 ml / cm 2 / s or more, more desirably 10 ml / cm 2 / s or more, even more desirably 20 ml / cm 2 / s or more.

[0037] The number of cells N2 (per 25 mm) of the second porous layer 12 is, for example, 50 ± 5 or more, desirably 55 ± 10 or more. Also, the average thickness t2 of the second porous layer 12 is, for example, 5 mm or more, desirably 15 to 30 mm. By providing the above-mentioned number of cells N2 and thickness t2, the second porous layer 12 alone is configured as a sponge material having a roughness such that at least visible light cannot pass through (that is, the opposite side cannot be seen through).

[0038] FIG. 5 conceptually shows a side view of the tire 1. In FIG. 5, the outer surface of the sound deadening body 10 and the boundary between the first porous layer 11 and the second porous layer 12 are indicated by broken lines. As shown in FIG. 5, the sound deadening body 10 of the present embodiment has an annular structure including a first end 10a in the tire circumferential direction, a second end 10b in the tire circumferential direction, and a fixing portion 13 that fixes the first end 10a and the second end 10b. Note that in FIG. 5, dots are applied to the fixing portion 13. Such a sound deadening body 10 can suppress the wear caused by the contact of the end portion of the sound deadening body 10 with a rim or the like, and excellent durability can be obtained.

[0039] The first end 10a and the second end 10b are fixed, for example, by an adhesive. In another embodiment, the first end 10a and the second end 10b may be welded.

[0040] In this embodiment, it is desirable that the annular sound deadening body 10 is slightly compressed and arranged in the tire inner cavity 1B (shown in FIG. 1) so that the sound deadening body 10 does not locally float from the pneumatic tire body 1A. Thereby, it is possible to prevent the sound deadening body 10 from contacting a rim or the like, and the durability of the sound deadening body 10 can be enhanced. Further, it is desirable that the first porous layer 11 (shown in FIG. 3) of the sound deadening body 10 is not fixed to the pneumatic tire body 1A. Thereby, for example, in a full-scale vehicle maintenance after an emergency puncture repair, the sound deadening body 10 penetrated by the puncture sealant can be easily replaced.

[0041] From the viewpoint of realizing the above-described aspect, when the fixing between the first end 10a and the second end 10b of the sound deadening body 10 is removed and the sound deadening body 10 is extended linearly on a plane in the natural state, the maximum length from the first end 10a to the second end 10b of the sound deadening body 10 is preferably 94% to 107% of the maximum circumference of the tire inner cavity 1B (shown in FIG. 1). Note that the maximum circumference of the tire inner cavity 1B means the maximum length in the tire circumferential direction on the inner surface of the pneumatic tire body 1A. In the present embodiment in which the tread portion 2 is convexly curved outward in the tire direction, the length of the circumference of the circle formed by the intersection of the inner surface of the pneumatic tire body 1A and the tire equatorial plane corresponds to the maximum circumference.

[0042] As described above in detail for the pneumatic tire and the like according to one embodiment of the present invention, the present invention is not limited to the above specific embodiments and can be implemented in various modes with modifications.

Example

[0043] A pneumatic tire having the basic structure of FIG. 1 and having a size of 215 / 55R17 based on the specifications in Table 1 was manufactured. Further, as a comparative example, a pneumatic tire in which the entire sound-absorbing body was composed of a porous layer with a ventilation volume of 42 ml / cm 2 / s was prototyped. The tire of the comparative example is substantially the same as the tire of the example except for the above matters. For these test tires, puncture reparability and sound absorption performance were evaluated. The common specifications and test methods of each test tire are as follows. Mounting rim: 17×7.5J Tire internal pressure: 250 kPa Material of sound-absorbing body: Polyurethane Axial length L1 of the sound-absorbing body in the tire: 100 mm, Thickness ta of the sound-absorbing body = 30 mm

[0044] <Puncture reparability> Immediately after forming a puncture hole with a diameter of 4 mm in the circumferential groove at the center of the tread of the test tire, 400 ml of a puncture sealant was injected into the tire inner cavity. Then, the tire internal pressure was adjusted to 200 kPa and the tire was run on a drum tester under the conditions of a load of 4.6 kN and a running speed of 30 km / h. Also, every minute it was checked whether the puncture hole was blocked, and the time until the puncture hole was completely blocked was measured. The result is an index with Example 1 as 100, and the smaller the numerical value, the shorter the time from injection of the puncture sealant until the puncture hole is blocked, indicating excellent puncture reparability.

[0045] <Sound absorption performance> A test tire was mounted on all wheels of a vehicle (engine displacement: 2000 cc, front-wheel drive vehicle), and the in-vehicle noise when driving on an asphalt road surface at 60 km / h was collected with a microphone installed at the ear position on the window side of the driver's seat. Further, among the in-vehicle noises, the sound pressure level of the peak value of the cavity resonance sound near 220 Hz in the narrow band was measured. The result is an index of the reduction value of the sound pressure level based on a tire without a sound deadening body, and 70 points or more is the passing level. The test results are shown in Table 1.

[0046]

Table 1

[0047] As shown in Table 1, it can be understood that the comparative example and each example have a sound absorption performance of 90 to 100 points, and can sufficiently suppress road noise and the like. On the other hand, the comparative example has a puncture reparability of 400 points, and the time until the puncture hole is blocked is long. In each example, the puncture reparability is 67 to 233 points, and it was confirmed that the puncture reparability was significantly improved.

[0048] [Appendix] The present invention includes the following aspects.

[0049] [Invention 1] A pneumatic tire capable of puncture repair by injecting a puncture sealant, including a pneumatic tire body that defines a tire inner cavity and a sound deadening body disposed in the tire inner cavity, the sound deadening body includes a first porous layer disposed on the inner cavity surface side of the tread portion of the pneumatic tire body and a second porous layer disposed on the inner side in the tire radial direction of the first porous layer, the air permeability of the first porous layer is greater than the air permeability of the second porous layer, pneumatic tire. [Invention 2] The air permeability measured according to JIS K6400-7 of the first porous layer is 62 ml / cm 2The pneumatic tire according to the first aspect of the present invention, having a hardness of 1.1 kPa or more at 25% compression load measured according to JIS K6400-2 D method. [The third aspect of the present invention] The pneumatic tire according to the first or second aspect of the present invention, wherein the hardness of the first porous layer at 25% compression load measured according to JIS K6400-2 D method is 1.1 kPa or more. [The fourth aspect of the present invention] The sound deadening body has a contact surface with the pneumatic tire body, The pneumatic tire according to any one of claims 1 to 3 of the present invention, wherein the entire contact surface is formed of the first porous layer. [The fifth aspect of the present invention] The pneumatic tire according to any one of claims 1 to 4 of the present invention, wherein the average thickness of the first porous layer is 2 to 10 mm. [The sixth aspect of the present invention] The pneumatic tire according to any one of claims 1 to 5 of the present invention, wherein the first porous layer is fixed to the second porous layer. [The seventh aspect of the present invention] The pneumatic tire according to any one of claims 1 to 6 of the present invention, wherein the sound deadening body is composed of only the first porous layer and the second porous layer. [The eighth aspect of the present invention] The pneumatic tire according to any one of claims 1 to 7 of the present invention, wherein the average thickness of the second porous layer is 5 mm or more. [The ninth aspect of the present invention] The pneumatic tire according to any one of claims 1 to 8 of the present invention, wherein the sound deadening body has an annular structure including a first end in the tire circumferential direction, a second end in the tire circumferential direction, and a fixing portion where the first end and the second end are fixed. [The tenth aspect of the present invention] The pneumatic tire according to any one of claims 1 to 9 of the present invention, wherein the first porous layer is not fixed to the pneumatic tire body. [The eleventh aspect of the present invention] The average density of the sound deadening body is 5 to 60 kg / m 3 The pneumatic tire according to any one of claims 1 to 10 of the present invention. [The twelfth aspect of the present invention] The pneumatic tire according to any one of claims 1 to 11 of the present invention, wherein the first porous layer and the second porous layer each have a foam structure in which an ether structure and an ester bond are mixed. [Invention 13] The pneumatic tire according to any one of claims 1 to 12 of the present invention, wherein the cross-sectional area of the sound deadening body is 3% to 20% of the total cross-sectional area of the pneumatic tire body and the tire inner cavity. [Invention 14] A sound deadening body for being disposed in the tire inner cavity of a pneumatic tire, wherein the sound deadening body includes a first porous layer disposed on the inner cavity surface side of the tread portion of the pneumatic tire, and a second porous layer disposed on the inner side in the tire radial direction with respect to the first porous layer. The air permeability of the first porous layer is greater than the air permeability of the second porous layer. Sound deadening body.

Explanation of reference numerals

[0050] 1A Pneumatic tire body 1B Tire inner cavity 2 Tread 10 Sound deadening body 11 First porous layer 12 Second porous layer

Claims

1. A pneumatic tire capable of puncture repair by injecting a puncture sealant, comprising: a pneumatic tire body defining a tire inner cavity, and a sound-absorbing body disposed in the tire inner cavity; the sound-absorbing body includes a first porous layer disposed on the inner cavity surface side of the tread portion of the pneumatic tire body, and a second porous layer disposed on the inner side in the tire radial direction of the first porous layer; the air permeability of the first porous layer is greater than the air permeability of the second porous layer; a pneumatic tire.

2. The air permeability measured in accordance with JIS K6400-7 of the first porous layer is 62 ml / cm 2 / s or more. The pneumatic tire according to claim 1.

3. The pneumatic tire according to claim 1 or 2, wherein the hardness of the first porous layer at a 25% compression load measured according to JIS K6400-2 D method is 1.1 kPa or more.

4. The sound-absorbing body has a contact surface with the pneumatic tire body, The pneumatic tire according to claim 1 or 2, wherein the entire contact surface is formed of the first porous layer.

5. The pneumatic tire according to claim 1 or 2, wherein the average thickness of the first porous layer is 2 to 10 mm.

6. The pneumatic tire according to claim 1 or 2, wherein the first porous layer is fixed to the second porous layer.

7. The pneumatic tire according to claim 1 or 2, wherein the sound-absorbing body is composed of only the first porous layer and the second porous layer.

8. The pneumatic tire according to claim 1 or 2, wherein the average thickness of the second porous layer is 5 mm or more.

9. The pneumatic tire according to claim 1 or 2, wherein the sound-absorbing body has an annular structure including a first end in the tire circumferential direction, a second end in the tire circumferential direction, and a fixing portion where the first end and the second end are fixed.

10. The pneumatic tire according to claim 1 or 2, wherein the first porous layer is not fixed to the pneumatic tire body.

11. The average density of the sound deadening body is 5 to 60 kg / m 3 The pneumatic tire according to claim 1 or 2, wherein the average density is as described above.

12. The pneumatic tire according to claim 1 or 2, wherein the first porous layer and the second porous layer each have a closed-cell structure in which an ether structure and an ester bond are mixed.

13. The pneumatic tire according to claim 1 or 2, wherein the cross-sectional area of the sound-absorbing body is 3% to 20% of the total cross-sectional area of the pneumatic tire body and the tire inner cavity.

14. A sound-absorbing body for being disposed in the tire inner cavity of a pneumatic tire, comprising: the sound-absorbing body includes a first porous layer disposed on the inner cavity surface side of the tread portion of the pneumatic tire, and a second porous layer disposed on the inner side in the tire radial direction of the first porous layer; The air permeability of the first porous layer is greater than that of the second porous layer. Sound insulating body.

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