Pneumatic tire

Abstract

To provide a pneumatic tire capable of restraining air leakage from being caused by side-cutting.SOLUTION: A pneumatic tire comprises a tread part 1 that assumes an annular shape by extending in a circumferential direction of the tire, and a pair of side parts 2 that are arranged on both the sides of the tread part 1. A sealant layer 20 is formed on a tire inner surface 10 of the side part 2. A sealant of the sealant layer 20 is composed of a silicone composition. The sealant layer 20 is arranged in the range of 20% or more of a height Hs of a cross-section of the side part 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire that is suitable for cases where weight reduction is important, and more specifically, to a pneumatic tire that can suppress air leakage due to side cuts. [Background technology]

[0002] In order to reduce rolling resistance, efforts are being made to reduce the weight of pneumatic tires. Weight reduction methods include not only reducing the thickness of the tread rubber layer but also thinning the side rubber layer. However, thinning the side rubber layer can cause side cuts, for example, when driving over a curb, which can lead to air leakage. Therefore, there is a need to suppress air leakage due to side cuts.

[0003] It has been proposed to provide a sealant layer on the radially inner side of the inner liner layer in the tread of a pneumatic tire. In such a pneumatic tire, when a foreign object such as a nail penetrates the tread, the sealant flows into the through-hole, thereby suppressing a decrease in air pressure and enabling the tire to continue running.

[0004] Conventionally, sealants constituting a sealant layer have generally been rubber compositions mainly containing butyl rubber (see, for example, Patent Documents 1 to 3). Examples of butyl rubber include butyl rubber (IIR) and halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR).

[0005] However, since the sealant layer made of the above-mentioned butyl-based rubber is prone to flow due to centrifugal force during running, if it is placed on the side portion, the sealant layer will move toward the tread portion as the tire runs, which poses a problem that air leakage due to side cuts cannot necessarily be suppressed. [Prior art documents] [Patent documents]

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a pneumatic tire capable of suppressing air leakage due to side cuts.

Means for Solving the Problems

[0008] The pneumatic tire of the present invention for achieving the above object is a pneumatic tire including a tread portion extending in the tire circumferential direction and having an annular shape, and a pair of side portions disposed on both sides of the tread portion, a sealant layer is formed on the inner surface of the tire in the side portion, and the sealant of the sealant layer is composed of a silicone-based composition, and the sealant layer is disposed in a region of 20% or more of the cross-sectional height of the side portion.

Effects of the Invention

[0009] In the present invention, a sealant layer including a sealant composed of a silicone-based composition is formed on the inner surface of the tire in the side portion, and the sealant layer is disposed in a region of 20% or more of the cross-sectional height of the side portion. Therefore, for example, when a side cut occurs when climbing over a curb, the sealant penetrates into the broken portion, and air leakage due to the side cut can be effectively suppressed. Further, since the sealant composed of the silicone-based composition is less likely to cause flow compared to the sealant composed of a rubber composition mainly composed of butyl rubber, the air leakage suppression effect can be maintained for a long period of time.

[0010] In the present invention, it is preferable that at least a portion of the sealant layer is disposed in an upper region that is 0% to 25% of the cross-sectional height of the side portion from the upper end position of the side portion. Also, it is preferable that at least a portion of the sealant layer is disposed in a lower region that is 25% to 50% of the cross-sectional height of the side portion from the lower end position of the side portion. The upper and lower regions of the side portion are prone to cuts, for example, when driving over a curb, so by disposing at least a portion of the sealant layer in these locations, air leakage can be efficiently suppressed with a minimum amount of sealant.

[0011] In the present invention, the silicone composition is preferably a two-component curing silicone, which has low viscosity immediately after mixing the two components, making it possible to apply the composition even at low temperatures.

[0012] In the present invention, the loss tangent tanδ of the sealant at 100°C is preferably in the range of 0.2 to 0.6. This allows optimization of sealing properties, flow resistance, and rolling resistance. The loss tangent tanδ is measured in accordance with JIS-K6394 using a viscoelasticity spectrometer under conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2%, and a temperature of 100°C.

[0013] In the present invention, the average thickness S of the sealant layer is preferably in the range of 2.0 mm to 5.0 mm, which makes it possible to optimize the sealing properties, flow resistance, and rolling resistance.

[0014] In the present invention, the ratio of the maximum distance L1 from the tire inner surface to the outermost layer of the carcass layer in an upper region that is 0% to 25% of the cross-sectional height of the side portion from the upper end position of the side portion to the average thickness S of the sealant layer preferably satisfies the relationship S / L1 ≧ 0.5. Also, the ratio of the maximum distance L2 from the tire inner surface to the outermost layer of the carcass layer in a lower region that is 25% to 50% of the cross-sectional height of the side portion to the average thickness S of the sealant layer preferably satisfies the relationship S / L2 ≧ 0.2. By making the average thickness S of the sealant layer sufficiently large compared to the distances L1 and L2, good sealing performance can be ensured.

[0015] In the present invention, in a pneumatic tire for which the mounting direction on a vehicle is specified, it is preferable that the sealant layer is disposed at least on the side portion on the outer side of the vehicle. Side cuts are particularly likely to occur on the side portion on the outer side of the vehicle, so by disposing the sealant layer at least on the side portion on the outer side of the vehicle, air leakage due to side cuts can be effectively suppressed.

[0016] In the present invention, the cross-sectional height of the sidewall is the radial height of the tire from the bead to the belt layer measured when the tire is mounted on a standard rim and inflated to the standard internal pressure. A "standard rim" is a rim determined for each tire by the standard system, including the standard on which the tire is based. For example, it is a standard rim for JATMA, a "Design Rim" for TRA, or a "Measuring Rim" for ETRTO. A "standard internal pressure" is an air pressure determined for each tire by the standard system, including the standard on which the tire is based. For JATMA, it is the maximum air pressure, for TRA, it is the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table, and for ETRTO, it is the "INFLATION PRESSURE." [Brief explanation of the drawings]

[0017] [Figure 1]1 is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view illustrating a method for manufacturing the pneumatic tire of FIG. 1. [Figure 3] 2 is a plan view showing a sealant layer formed on the inner surface of the pneumatic tire of FIG. 1. FIG. [Figure 4] FIG. 10 is a meridian cross-sectional view showing a pneumatic tire according to another embodiment of the present invention. [Figure 5] 5 is a cross-sectional view showing an upper region of a side portion of the pneumatic tire of FIG. 4. FIG. [Figure 6] 5 is a cross-sectional view showing an extracted lower region of a side portion of the pneumatic tire of FIG. 4. FIG. [Figure 7] FIG. 10 is a meridian cross-sectional view showing a pneumatic tire according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 shows a pneumatic tire according to an embodiment of the present invention;

[0019] As shown in FIG. 1, the pneumatic tire of this embodiment includes a tread portion 1 extending in the tire circumferential direction to form an annular shape, and a pair of side portions 2, 2 disposed on both sides of the tread portion 1.

[0020] A bead core 5 is embedded in each side portion 2. A carcass layer 4 is installed between the pair of bead cores 5, 5 so as to extend from one side portion 2 to the other side portion 2. This carcass layer 4 includes a plurality of carcass cords extending in the tire radial direction, and is folded back around each bead core 5 from the inside to the outside of the tire. A bead filler 6 made of a rubber composition and having a triangular cross section is arranged on the outer periphery of the bead core 5.

[0021] On the other hand, multiple belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include multiple belt cords that are inclined with respect to the tire circumferential direction, and are arranged so that the belt cords cross each other between the layers. In the belt layers 7, the inclination angle of the belt cords with respect to the tire circumferential direction is set in the range of 10° to 40°, for example. Steel cords are preferably used as the belt cords of the belt layers 7.

[0022] At least one belt cover layer 8 is arranged on the outer periphery of the belt layer 7, with the aim of improving high-speed durability, and is made up of reinforcing cords arranged at an angle of, for example, 5° or less relative to the tire circumferential direction. This belt cover layer 8 preferably has a jointless structure in which a strip material made of at least one reinforcing cord that has been aligned and rubber-coated is continuously wound at an angle of substantially 0° relative to the tire circumferential direction. The reinforcing cord of the belt cover layer 8 is preferably an organic fiber cord such as nylon or polyethylene terephthalate (PET).

[0023] The tire internal structure described above is a typical example of a pneumatic tire, but is not limited to this. Various grooves, including a plurality of main grooves 11 extending in the tire circumferential direction, are formed in the tread portion 1.

[0024] In the pneumatic tire, a sealant layer 20 is formed continuously in the tire circumferential direction on the tire inner surface 10 in the tread portion 1 and the side portion 2. The sealant in the sealant layer 20 is composed of a silicone-based composition. The silicone-based composition includes a synthetic polymer compound having a main skeleton formed by siloxane bonds.

[0025] In the above pneumatic tire, the sealant layer 20 is disposed in an area that is 20% or more of the cross-sectional height Hs of the side portion 2. That is, the cross-sectional height Hc in the tire radial direction of the area in which the sealant layer 20 is disposed in the side portion 2 is 20% or more of the cross-sectional height Hs of the side portion 2. The sealant layer 20 may be divided into multiple areas in the side portion 2, and the sum of the cross-sectional heights Hc of the areas where the sealant layer 20 is disposed satisfies the above relationship.

[0026] In the pneumatic tire described above, a sealant layer 20 containing a sealant made of a silicone-based composition is formed on the tire inner surface 10 of the side portion 2, and the sealant layer 20 is disposed in an area that is 20% or more of the cross-sectional height Hs of the side portion 2. Therefore, if a side cut occurs, for example, when driving over a curb, the sealant penetrates the ruptured portion, effectively suppressing air leakage due to the side cut. Furthermore, a sealant made of a silicone-based composition is less likely to flow than a sealant made of a rubber composition primarily containing butyl rubber, so it is possible to maintain its air leakage suppression effect for a long period of time. Here, if the cross-sectional height Hc of the region where the sealant layer 20 is disposed in the side portion 2 is less than 20% or more of the cross-sectional height Hs of the side portion 2, air leakage due to the side cut cannot be sufficiently suppressed.

[0027] In this embodiment, the sealant layer 20 is preferably disposed not only in the side portion 2 but also in the tread portion 1, but from the viewpoint of suppressing air leakage due to side cuts, a structure in which the sealant layer 20 is not present in the tread portion 1 is also acceptable.

[0028] The above-described pneumatic tire can be manufactured by the following method. First, a pneumatic tire is manufactured as described above, which includes the tread portion 1 and a pair of side portions 2, and has the belt layer 7 and belt cover layer 8 embedded in the tread portion 1. Next, a sealant made of a silicone-based composition is applied to the tire inner surface 10 to form the sealant layer 20.

[0029] FIG. 2 shows a specific manufacturing method for the pneumatic tire of FIG. 1, and FIG. 3 shows a sealant layer formed on the tire inner surface. In FIG. 2, a sealant extrusion device 31 mixes sealants supplied from pumps 32 and 33 and continuously discharges the mixed sealant as a strip 21 from a nozzle 34. The sealant extrusion device 31 is configured so that the position of the nozzle 34 can be freely changed. Therefore, by moving the nozzle 34 in the axial direction of the tire while rotating the tire from a state in which the nozzle 34 is close to the tire inner surface 10, the sealant strip 21 can be arranged spirally on the tire inner surface 10 while being inclined with respect to the tire circumferential direction Tc (see FIG. 3). The spirally arranged sealant strips 21 are in close contact with each other at their circumferential portions. The spirally arranged sealant strips 21 are integrated to form the sealant layer 20.

[0030] In the pneumatic tire described above, a sealant layer 20 is formed on the tire inner surface 10, with a sealant strip 21 spirally arranged along the tire circumferential direction. Because the sealant is composed of a silicone-based composition, the circumferential portions of the sealant strip 21 fit together easily during the curing reaction of the silicone-based composition, improving the integrity of the circumferential portions of the sealant strip 21. This improves the sealing performance of the sealant layer 20. Furthermore, because the circumferential portions of the sealant strip 21 are well-integrated, centrifugal force generated during tire rotation makes it difficult for the sealant layer 20 to flow toward the tire widthwise center, which also contributes to improved sealing performance. Furthermore, using a silicone-based composition as the sealant for the sealant layer 20 offers the advantages of excellent weather resistance and low temperature dependency of physical properties.

[0031] When a sealant made of a rubber composition mainly containing butyl rubber is used, a sealant layer is formed by heating a strip of sealant to a high temperature and softening it, and then spirally arranging it around the tire's inner surface in the circumferential direction. However, in a sealant layer formed in this manner, the sealant cools before the wrapped portions of the sealant strip have time to blend together, resulting in poor unity between the wrapped portions of the sealant strip and resulting in insufficient sealing by the sealant layer.

[0032] Because silicone-based compositions have good fluidity even at low temperatures, it is preferable to set the temperature of the sealant applied to the tire inner surface 10 to below 70°C. This reduces the thermal impact on the tire and prevents deterioration of tire performance. If this temperature is 70°C or higher, the thermal impact on the tire will be greater, which will cause deterioration of tire performance. In particular, it is desirable for the temperature of the sealant applied to the tire inner surface 10 to be 35°C or lower. Furthermore, from the viewpoint of the fluidity of the silicone-based composition, it is preferable for the lower limit of the temperature of the sealant applied to the tire inner surface 10 to be 20°C.

[0033] The silicone-based composition constituting the sealant of the sealant layer 20 can be a one-component curing silicone or a two-component curing silicone, with two-component curing silicone being particularly preferred. Examples of one-component curing silicones include moisture-curing silicone. Two-component curing silicones are composed of a first component and a second component, and mixing these components initiates a curing reaction, ensuring the stability of the sealant layer 20 after curing. In the above-described device, the first component and the second component of the two-component curing silicone are supplied from pumps 32 and 33, respectively. Two-component curing silicones have low viscosity immediately after mixing, allowing them to be applied even at low temperatures. In particular, two-component curing silicones that take 5 days or more to fully cure are preferred.

[0034] Two-component curing silicones are composed of, for example, a condensation-curable silyl-terminated polymer, a silane crosslinker, a condensation catalyst, a filler, and the like. Examples of condensation-curable silyl-terminated polymers include polydialkylsiloxanes, alkylphenylsiloxanes, organic polymers having silyl groups (e.g., silyl polyethers, silyl acrylates), and polyisobutylenes having silyl groups. Examples of silane crosslinkers include alkoxy-functional silanes, oximosilanes, acetoxysilanes, and enoxysilanes. Examples of fillers include iron oxide, titanium dioxide, carbon black, and talc. Examples of condensation catalysts include titanates and zirconates. These condensation-curable silyl-terminated polymers, silane crosslinkers, condensation catalysts, and fillers are stored in a first and second liquid form in a combination that does not promote a curing reaction, and are mixed when used.

[0035] In the above pneumatic tire, it is preferable that the tan δ of the sealant of the sealant layer 20 at 100°C is in the range of 0.2 to 0.6. This allows optimization of sealing performance, flow resistance, and rolling resistance. Here, if the tan δ of the sealant at 100°C is 0.2 or more, sealing performance will be good, and it is particularly preferable that it is 0.3 or more. If the tan δ of the sealant at 100°C is 0.6 or less, rolling resistance and flow resistance will be good, and it is particularly preferable that it is 0.5 or less.

[0036] In the above-described pneumatic tire, the average thickness S of the sealant layer 20 is preferably in the range of 2.0 mm to 5.0 mm, as shown in Figure 1. This allows optimization of sealing performance, flow resistance, and rolling resistance. If the average thickness S of the sealant layer 20 is less than 2.0 mm, sealing performance will decrease. Conversely, if it is greater than 5.0 mm, rolling resistance will decrease due to increased tire weight, and flow of the sealant will decrease flow resistance.

[0037] FIG. 4 shows a pneumatic tire according to another embodiment of the present invention, FIG. 5 shows an upper region of a side portion, and FIG. 6 shows a lower region of the side portion. In FIG. 4, a sealant layer 20 containing a sealant made of a silicone-based composition is formed on the tire inner surface 10 of the side portion 2. Here, assuming that the region from the upper end position of the side portion 2 to 0% to 25% of the cross-sectional height Hs of the side portion 2 is defined as an upper region Au, at least a portion of the sealant layer 20 is disposed in the upper region Au. Furthermore, assuming that the region from the lower end position of the side portion 2 to 25% of the cross-sectional height Hs of the side portion 2 is defined as a lower region Al, at least a portion of the sealant layer 20 is disposed in the lower region Al. The upper region Au and lower region Al of the side portion 2 are prone to cuts when pinched between a curb and the rim, for example, when driving over a curb. Therefore, disposing at least a portion of the sealant layer 20 in these locations can efficiently suppress air leakage with a minimum amount of sealant. The above-mentioned effects are expected from the presence of a portion of the sealant layer 20 in the upper region Au and the lower region Al of the side portion 2, but to fully exert these effects, it is desirable that the sealant layer 20 be disposed over 50% or more of each of the upper region Au and the lower region Al. Of course, a portion of the sealant layer 20 may be present in only one of the upper region Au and the lower region Al.

[0038] In the pneumatic tire, the ratio of the maximum distance L1 from the tire inner surface 10 to the outermost layer of the carcass layer 4 in an upper region Au, which is 0% to 25% of the cross-sectional height Hs of the side portion 2 from the upper end position of the side portion 2, to the average thickness S of the sealant layer 20 preferably satisfies the relationship S / L1 ≧ 0.5. Furthermore, the ratio of the maximum distance L2 from the tire inner surface 10 to the outermost layer of the carcass layer 4 in a lower region Al, which is 25% to 50% of the cross-sectional height Hs of the side portion 2 from the lower end position of the side portion 2, to the average thickness S of the sealant layer 20 preferably satisfies the relationship S / L2 ≧ 0.2. When the average thickness S of the sealant layer is sufficiently large relative to the distances L1 and L2, the sealant can easily reach the carcass layer 4 when a side cut occurs, thereby achieving good sealing performance. If the ratio S / L1 or S / L2 is smaller than the above-mentioned lower limit, the improvement in sealing performance is reduced.

[0039] Figure 7 shows a pneumatic tire according to yet another embodiment of the present invention. This pneumatic tire is a tire for which the orientation of the front and back of the tire when mounted on a vehicle is specified. In Figure 7, IN is the inside of the vehicle when mounted on the vehicle, and OUT is the outside of the vehicle when mounted on the vehicle. At least one side portion 2 is provided with an indicator 2A that indicates the mounting orientation relative to the vehicle.

[0040] 7, in a pneumatic tire for which the mounting direction relative to a vehicle is specified, the sealant layer 20 is not disposed on the side portion 2i on the inside of the vehicle, but is disposed only on the side portion 2o on the outside of the vehicle. Since side cuts are particularly likely to occur on the side portion 2o on the outside of the vehicle, disposing the sealant layer 20 at least on the side portion 2o on the outside of the vehicle can effectively prevent air leakage due to side cuts. [Example]

[0041] In a pneumatic tire having a tire size of 255 / 40R21 and equipped with a tread portion and a pair of side portions, a sealant layer was formed on the inner surface of the tire in at least the tread portion, and tires of Conventional Examples 1-2, Comparative Examples 1-2, and Examples 1-14 were produced with various changes as shown in Tables 1 and 2, such as the minimum thickness of the side portion, the constituent material of the sealant layer, the presence or absence of a sealant layer in the side portion, the ratio of the sealant layer area to the cross-sectional height of the side portion, the ratio of the sealant layer area in the upper region of the side portion, the ratio of the sealant layer area in the lower region of the side portion, the tan δ of the sealant at 100°C, the average thickness S of the sealant layer, and the ratios S / L1 and S / L2.

[0042] These test tires were evaluated for rolling resistance, air leakage occurrence rate, and flow resistance by the following test methods, and the results are shown in Tables 1 and 2.

[0043] Rolling resistance: Each test tire was mounted on a wheel with a rim size of 21 x 9.0J and attached to a rolling resistance tester, and the rolling resistance was measured in accordance with JIS-D4234 at an air pressure of 250 kPa. The evaluation results were expressed as an index using the reciprocal of the measured value, with Conventional Example 1 being set at 100. The higher the index value, the lower the rolling resistance.

[0044] Air leak rate: Each test tire was mounted on a 21x9.0J rim wheel, inflated to 270kPa, and mounted on an SUV (2000cc engine), and a curb-driving test was conducted at a temperature of 23°C. In the curb-driving test, the right front tire was driven over an 80mm high protrusion (curb) that was inclined at a 15° angle to the normal to the tire's direction of travel, and the speed at which the tire drove over the curb was increased in 5km / h increments from 30km / h, and the maximum speed at which air leakage did not occur after driving was measured. The higher this maximum speed, the greater the effectiveness of suppressing air leakage due to side cuts.

[0045] Flow Resistance: Each test tire was mounted on a 21x9.0J rim wheel, inflated to 230kPa, and mounted on an indoor drum testing machine (drum diameter 1707mm). The ambient temperature was controlled at 38±3°C, and the tire was driven for one hour at a speed of 200km / h under a load of 88% of the JATMA maximum load. The degree of sealant flow on the inner surface of the tire was then checked. The evaluation results were indicated as follows: no flow at all (◎), slight flow (less than 1 / 8 of the total width of the sealant layer) (〇), slight flow (less than 1 / 4 of the total width of the sealant layer) (△), and heavy flow (more than 1 / 4 of the total width of the sealant layer) (×).

[0046] [Table 1]

[0047] [Table 2]

[0048] As can be seen from Tables 1 and 2, the tires of Examples 1 to 13 were more effective in suppressing air leakage due to side cuts and had good resistance to flow of the sealant layer compared to Conventional Example 1. Furthermore, Conventional Example 2, which had thicker side sections, had a higher rolling resistance than Conventional Example 1, but Examples 1 to 13 had a lower rolling resistance than Conventional Example 1. In contrast, the tire of Comparative Example 1 used a sealant made of diene rubber, which resulted in a low effect of suppressing air leakage due to side cuts and insufficient resistance to flow of the sealant layer. Furthermore, the tire of Comparative Example 2 had a small area in the side sections where the sealant layer was located, which resulted in a low effect of suppressing air leakage due to side cuts.

[0049] The present disclosure includes the following inventions [1] to [9]. The invention [1] is a pneumatic tire having a tread portion extending in the tire circumferential direction and forming an annular shape, and a pair of side portions disposed on both sides of the tread portion, a sealant layer is formed on the tire inner surface in the side portion, and the sealant in the sealant layer is made of a silicone-based composition, The pneumatic tire is characterized in that the sealant layer is disposed in an area of ​​20% or more of the cross-sectional height of the side portion. Invention [2] is a pneumatic tire according to invention [1], characterized in that at least a portion of the sealant layer is disposed in an upper region that is 0% to 25% of the cross-sectional height of the side portion from the upper end position of the side portion. Invention [3] is a pneumatic tire according to invention [1] or [2], characterized in that at least a portion of the sealant layer is disposed in a lower region that is 25% to 50% of the cross-sectional height of the side portion from the lower end position of the side portion. Invention [4] is the pneumatic tire according to any one of inventions [1] to [3], characterized in that the silicone composition is a two-component curing silicone. Invention [5] is the pneumatic tire according to any one of inventions [1] to [4], characterized in that the tan δ of the sealant at 100° C. is in the range of 0.2 to 0.6. Invention [6] is the pneumatic tire according to any one of inventions [1] to [5], characterized in that the average thickness S of the sealant layer is in the range of 2.0 mm to 5.0 mm. Invention [7] is a pneumatic tire according to any one of inventions [1] to [6], characterized in that the ratio of the maximum distance L1 from the inner surface of the tire to the outermost layer of the carcass layer in an upper region that is 0% to 25% of the cross-sectional height of the side portion from the upper end position of the side portion to the average thickness S of the sealant layer satisfies the relationship S / L1≧0.5. Invention [8] is a pneumatic tire according to any one of inventions [1] to [7], characterized in that the ratio of the maximum distance L2 from the inner surface of the tire to the outermost layer of the carcass layer in a lower region that is 25% to 50% of the cross-sectional height of the side portion from the lower end position of the side portion to the average thickness S of the sealant layer satisfies the relationship S / L2≧0.2. Invention [9] is a pneumatic tire according to any one of inventions [1] to [8], characterized in that the sealant layer is disposed at least on the side portion on the outer side of the vehicle in a pneumatic tire having a specified mounting direction on a vehicle. [Explanation of symbols]

[0050] 1 Tread section 2 Sidewall 4 carcass layers 5 bead core 6 Bead filler 7 Belt Layer 8 Belt cover layer 10 Tire inner surface 20 Sealant Layer 21 Sealant Strip

Claims

1. A pneumatic tire having a tread portion extending in a circumferential direction of the tire to form an annular shape, and a pair of side portions disposed on both sides of the tread portion, a sealant layer is formed on the tire inner surface in the side portion, and the sealant in the sealant layer is made of a silicone-based composition, A pneumatic tire characterized in that the sealant layer is disposed in an area of ​​the side portion that is 20% or more of the cross-sectional height.

2. The pneumatic tire according to claim 1, characterized in that at least a portion of the sealant layer is disposed in an upper region that is 0% to 25% of the cross-sectional height of the side portion from the upper end position of the side portion.

3. The pneumatic tire according to claim 1 or 2, characterized in that at least a portion of the sealant layer is disposed in a lower region that is 25% to 50% of the cross-sectional height of the side portion from the lower end position of the side portion.

4. 3. The pneumatic tire according to claim 1, wherein the silicone-based composition is a two-component curing silicone.

5. 3. The pneumatic tire according to claim 1, wherein the sealant has a tan δ at 100° C. in the range of 0.2 to 0.

6.

6. 3. The pneumatic tire according to claim 1, wherein the sealant layer has an average thickness S in the range of 2.0 mm to 5.0 mm.

7. 3. The pneumatic tire according to claim 1, wherein a ratio of a maximum distance L1 from the inner surface of the tire to the outermost layer of the carcass layer in an upper region that is 0% to 25% of the cross-sectional height of the side portion from the upper end position of the side portion to an average thickness S of the sealant layer satisfies the relationship S / L1≧0.

5.

8. 3. The pneumatic tire according to claim 1, wherein a ratio of a maximum distance L2 from the inner surface of the tire to the outermost layer of the carcass layer in a lower region that is 25% to 50% of the cross-sectional height of the side portion from the lower end position of the side portion to an average thickness S of the sealant layer satisfies the relationship S / L2≧0.

2.

9. 3. The pneumatic tire according to claim 1, wherein the sealant layer is disposed at least on a side portion on an outer side of the vehicle in a pneumatic tire having a specified mounting direction relative to the vehicle.

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