pneumatic tires

Abstract

Pneumatic tires, comprising: a tread portion (1) extending in a tire circumferential direction and having a ring shape; a pair of sidewall portions (2) arranged on opposite sides of the tread portion (1); a pair of bead portions (3) arranged inwardly of the sidewall portions (2) in the tire radial direction; a bead core (5) provided in each of the bead portions (3); a carcass layer (4) disposed between the pair of tire bead portions (3); and a side reinforcing layer (8) provided in the tire transverse direction inward of the carcass layer (4) in the sidewall portion (2) and having a crescent shape in cross section; where the bead core (5) comprises at least one bead wire (5A) wound in the tire circumferential direction, a plurality of circumferential portions of the bead wire (5A) form at least one row arranged in the tire transverse direction and a plurality of layers overlapping in the tire radial direction, a width W0 of one of the plurality of layers including a maximum number of rows, a width W1 of another of the plurality of layers located on the innermost side in the tire radial direction, and a width W2 of another of the plurality of layers located on the outermost side in the tire radial direction satisfy the relationships W1 > W2 and W2 ≤ 0.5 × W0, the layer of the plurality of layers including the maximum number of rows is located inward in the tire radial direction from the center position of the bead core (5) in the tire radial direction, the carcass layer (4) includes a body portion (4A) extending from the tread portion (1) through each of the sidewall portions (2) to each of the bead portions (3), and a folded-back portion (4B) folded at each of the bead portions (3) and curved along a circumference of the bead core (5) and extending to each of the sidewall portions (2) while contacting the body portion (4A) from an outer end position of the bead core (5) in the tire radial direction, a ratio of a total area of the rubber present in a closed region to an area of the closed region formed by the body portion (4A) and the folded-back portion (4B) of the carcass layer (4) is 0.1% to 15%, a filler layer (9) is provided in the tire transverse direction outward of the body portion (4A) and the folded-back portion (4B) of the carcass layer (4), and a cross-sectional area S1 of the side reinforcement layer (8) and a hardness H1 of the side reinforcement layer (8) as well as a cross-sectional area S2 of the filler layer (9) and a hardness H2 of the filler layer (9) satisfy a relationship 0.12 ≤ (S2 × H2) / (S1 × H1) ≤ 0.50.

Description

Technical area

[0001] The present invention relates to a pneumatic tire provided with a side reinforcing layer on a sidewall portion, and more particularly relates to a pneumatic tire having an improved structure of a bead portion, enabling a reduction in tire weight while maintaining tire durability. State of the art

[0002] Generally, a bead core and a bead filler are embedded in a bead portion of a pneumatic tire. Furthermore, a pneumatic tire (a so-called run-flat tire) that can safely travel a certain distance even when a puncture occurs is structured such that a side reinforcing layer (a layer of hard rubber having a crescent-shaped cross-sectional shape) is provided on a sidewall portion to bear a load applied by a vehicle when the tire is punctured. In such a tire, an inner end portion of the side reinforcing layer in the tire radial direction may reach a position near the bead portion. Accordingly, the thickness of the position near the bead portion increases, and thus the likelihood of the tire weight increasing increases.

[0003] On the other hand, in recent years, tire weight reduction has been strongly demanded, and weight reduction of the aforementioned pneumatic tire has also been considered. For example, in Patent Document 1, a pneumatic tire provided with a side reinforcing layer having a crescent-shaped cross-section is structured to construct the shape of a bead core, thus omitting a bead filler. However, even if such a tire can be reduced in weight, the rigidity at a location near a bead portion is low. Accordingly, tire durability cannot be sufficiently achieved. Thus, an additional countermeasure is required. Literature listPatent literature

[0004] Patent Document 1: JP 2002-301915 A Brief description of the inventionTechnical problem

[0005] An object of the present invention is to provide a pneumatic tire including a side reinforcing layer on a sidewall portion which provides an improved structure of a bead portion, enabling a reduction in tire weight while maintaining tire durability. Solution to the problem

[0006] To achieve the above-described object, a pneumatic tire according to an embodiment of the present invention includes: a tread portion extending in the tire circumferential direction and having an annular shape; a pair of sidewall portions disposed on opposite sides of the tread portion; a pair of bead portions disposed inward from the sidewall portions in the tire radial direction; a bead core provided in each of the bead portions; a carcass portion disposed between the pair of bead portions; and a side reinforcing layer provided inward of the carcass layer in the sidewall portion in the tire transverse direction and having a crescent shape in cross section. The bead core includes at least one bead wire wound in the tire circumferential direction.A plurality of circumferential portions of the bead wire form at least one row arranged in the tire transverse direction and a plurality of layers overlapping in the tire radial direction. A width W0 of one of the plurality of layers including a maximum number of rows and a width W1 of another of the plurality of layers located on the innermost side in the tire radial direction satisfy the relationships W1 > W2 and W2 ≤ 0.5 × W0. The layer of the plurality of layers including the maximum number of rows is located inward in the tire radial direction from the center position of the bead core in the tire radial direction.The carcass layer includes a body portion extending from the tread portion through each of the sidewall portions to each of the bead portions, and a folded-back portion folded at each of the bead portions and curved along a circumference of the bead core and extending to each of the sidewall portions while contacting the body portion from an outer end position of the bead core in the tire radial direction. The ratio of a total area of the rubber present in a closed region to an area of the closed region formed by the body portion and the folded-back portion of the carcass layer is 0.1% to 15%. A filler layer is provided outward of the body portion and the folded-back portion of the carcass layer in the tire transverse direction.A cross-sectional area S1 of the side reinforcement layer and a hardness H1 of the side reinforcement layer as well as a cross-sectional area S2 of the filler layer and a hardness H2 of the filler layer satisfy a relationship. 0.12≤(S2×H2) / (S1×H1)≤0.50. Advantageous effects of the invention

[0007] According to one embodiment of the present invention as described above, the ratio of the total area of the rubber present in the closed region to the area of the closed region formed by the body portion and the folded-back portion of the carcass layer is small, from 0.1% to 15%. Accordingly, only the bead core is substantially present in the closed region, and thus the tire weight can be reduced. In this case, the bead core has the shape described above, and the folded-back portion of the carcass layer extends along the periphery of the bead core having the shape and also extends to the sidewall portion while contacting the body portion from the outer end position of the bead core in the tire radial direction.Furthermore, the side reinforcing layer and the filler layer satisfying the relationship between the above-mentioned cross-sectional areas and the above-mentioned hardnesses are provided. Accordingly, even in a case where a bead filler (or a tire component similar to the bead filler) is not substantially present between the body portion and the folded-back portion of the carcass layer as in a prior art tire, adequate rigidity can be ensured in a region near the bead portion. Thus, normal driving performance and run-flat performance can be favorably maintained.Furthermore, in the tire according to an embodiment of the present invention, the filler layer is provided as described above; however, the filler layer is disposed outward of the body portion and the folded-back portion of the carcass layer in the tire transverse direction as described above, and satisfies the relationship between the above-mentioned cross-sectional areas and the above-mentioned hardnesses. Accordingly, the filler layer differs from a prior art bead filler in that the filler layer can effectively increase the rigidity of the area near the bead portion without being an element that increases the tire weight. In addition, the hardness of each of the layers is a hardness (so-called JIS-A hardness) measured with a Type A durometer and at a temperature of 20°C, and conforms to JIS K6253.

[0008] According to one embodiment of the present invention, one end of the folded-back portion of the carcass layer is preferably in contact with the filler layer. Consequently, the end of the folded-back portion, which is likely to be the origin of the crack, can be prevented from being stressed, which is beneficial for improving tire durability. Furthermore, with such a structure, the length of the folded-back portion of the carcass layer can ultimately be reduced and the amount of carcass layer used can be minimized, thus also being effective in reducing tire weight.

[0009] According to an embodiment of the present invention, a rim width BW and a maximum width of the tire inner surface IW preferably satisfy the relationship 0.95 ≤ IW / BW ≤ 1.20 when the tire is mounted on a regular rim and inflated to a regular inner pressure. The rim width BW is set to correspond to the maximum width of the tire inner surface IW as just described, and thus the side reinforcing layer can be formed in a good shape and the runflat performance can be improved. Furthermore, according to an embodiment of the present invention, since there is substantially no bead filler as described above, the curved shape of the carcass layer can be easily changed, and the tire structure in which the rim width BW and the maximum width of the tire inner surface IW satisfy the above relationship can be easily achieved.

[0010] According to one embodiment of the present invention, at least a portion of the bead wire is preferably layered in a trefoil shape. Accordingly, the bead wire is densely arranged, and the filling ratio is increased. Thus, the bead core structure is optimized. Consequently, the rigidity and pressure resistance of the bead portion can be adequately ensured, and the weight of the tire can be reduced while maintaining the same mileage, and thus these performances can be advantageously achieved in a balanced manner.

[0011] According to one embodiment of the present invention, when a polygon formed by common tangent lines of a plurality of circumferential portions of the bead wire in a meridian cross section is defined as an outer shape of the bead wire, an interior angle of at least one of the corner portions located at opposite ends of one side of the outer shape disposed inward in the tire radial direction is equal to or greater than 90°. This can prevent the arrangement of the bead wire from being disturbed during vulcanization, and the bead core can have a good shape after vulcanization, which is advantageous for reducing tire weight while ensuring excellent rigidity.

[0012] According to one embodiment of the present invention, a total thickness T1 in the tire axial direction of the sidewall portion located at a tire maximum width position and a minimum value T2 of a total thickness in the tire axial direction of the sidewall portion located in a region where the filler layer is present satisfy the relationship 0.7≤T2 / T1≤1.1. Therefore, the tire shape from the tire maximum width position to the bead portion is favorably formed, which is advantageous for reducing tire weight while ensuring excellent rigidity.

[0013] According to one embodiment of the present invention, a height h0 of the side reinforcing layer from a bead toe position, a height h1 from the bead toe position to a position where the thickness of the filler layer is maximum, and a height h2 from the bead toe position to an end of the folded-back portion of the carcass layer satisfy the relationships h1 > h2 and 0.15 ≤ h1 / h0 ≤ 0.45. Therefore, the tire shape in the region where the filler layer is present is favorably formed, which is advantageous for reducing tire weight while ensuring excellent rigidity.

[0014] According to one embodiment of the present invention, a length L1 along the carcass layer of a region where the side reinforcing layer and the filler layer are overlapped in a state where the carcass layer is disposed between the side reinforcing layer and the filler layer, and a length L2 along the carcass layer of a region where the body portion and the folded-back portion of the carcass layer are in contact satisfy the relationship 1≤L1 / L2≤5. Therefore, in order to reduce the tire weight while maintaining excellent rigidity, the positional relationships between the components of the tire are appropriately determined, and appropriate flexibility can be applied to a region from the sidewall portion to a location near the bead portion. Furthermore, ride comfort can be improved.

[0015] In the present invention, the dimensions are measured by mounting the tire on a standard rim and inflating it to a standard internal pressure. "Regular rim" is a rim defined by a standard for each tire according to a system of standards that includes standards on which tires are based, and refers to a "standard rim" in the case of JATMA, a "design rim" in the case of TRA, and a "measuring rim" in the case of ETRTO.In the system of standards, including standards that tires meet, "regular air pressure" is an air pressure defined by each of the standards for each tire and is referred to as "maximum air pressure" in the case of JATMA, the maximum value in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table in the case of TRA, and "INFLATION PRESSURE" in the case of ETRTO. However, the "regular air pressure" is 180 kPa in a case where a tire is a passenger car tire. Brief description of the drawings Fig. 1 is a half cross-sectional view taken along a meridian of a pneumatic tire according to an embodiment of the present invention. Fig.2 is an explanatory diagram schematically illustrating a multilayer structure of a bead wire according to an embodiment of the present invention. Fig. 3A to 3C are explanatory diagrams schematically illustrating multilayer structures of a bead wire according to embodiments of the present invention. Fig. 4 is an explanatory diagram schematically illustrating multilayer structures of a bead wire according to embodiments of the present invention. Fig. 5 is a meridian cross-sectional view of a pneumatic tire according to another embodiment of the present invention. Fig. 6 is a meridian cross-sectional view of a pneumatic tire according to another embodiment of the present invention. Description of embodiments

[0016] Configurations of embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] As in Fig. 1, the pneumatic tire of one embodiment of the present invention includes a tire circumferentially extending annular tread portion 1, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed inwardly of the sidewall portions 2 in the tire radial direction. Note that "CL" in Fig. 1 denotes the tire equator.

[0018] A carcass layer 4 is interposed between the pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction and is folded back around a bead core 5 disposed in each of the bead portions 3 from a vehicle inner side toward a vehicle outer side. In the following description, a portion of the carcass layer extending from the tread portion 1 through each of the sidewall portions 2 to each of the bead portions 3 is referred to as a body portion 4A, and a portion of the carcass layer folded back around the bead core 5 at each of the bead portions 3 to extend to each of the sidewall portions 2 is referred to as 4B.

[0019] As shown in an enlarged view of Fig.As shown in Fig. 2, the bead core 5 is formed of at least one bead wire 5A wound in the tire circumferential direction, and a plurality of circumferential portions of the bead wire 5A form a plurality of rows aligned in the tire transverse direction and a plurality of layers overlapped in the tire radial direction. As long as the plurality of circumferential portions of the bead wire 5A form the plurality of rows and the plurality of layers in the meridian cross section as described above, even a so-called single-winding structure in which the single bead wire 5A is continuously wound, or even a so-called ply-winding structure in which the plurality of bead wires 5A are aligned in parallel can be adopted in the present invention. The structure of the bead wire 5A itself is not particularly limited, but an average diameter of the bead wire 5A is preferably from 0.8 mm to 1.8 mm, more preferably from 1.0 mm to 1.6 mm, and even more preferably from 1.1 mm to 1.5 mm.In addition, the total cross-sectional area of the bead wire 5A (the sum of the cross-sectional areas of the peripheral portions of the bead wire 5A included in the meridian cross section of each of the bead cores 5) is preferably from 10 mm2 to 50 mm2, more preferably from 15 mm. 2 up to 48 mm 2 , and even more preferably from 20 mm 2 up to 45 mm 2In the illustrated example, a structure is provided in which a total of five layers: one layer including four rows of circumferential portions; one layer including five rows of circumferential portions; one layer including four rows of circumferential portions; one layer including three rows of circumferential portions; and one layer including two rows of circumferential portions are stacked in the mentioned order from the innermost side in the tire radial direction. Note that the structure will be referred to as a "4 + 5 + 4 + 3 + 2 structure" in the following description. Likewise, in the following description, the multi-layer structure of the bead wire 5A is expressed in a similar format such that the number of rows included in the respective layers is connected with a "+" in the order from the innermost layer in the tire radial direction.Furthermore, in the bead core 5 of the illustrated example, the bead core 5A is arranged to form a trefoil-shaped multilayer structure. Note that the "trefoil-shaped multilayer structure" is a stacking method in which the centers of the three circumferential portions in contact with each other form a substantially regular triangle, and it is a multilayer structure, also called a hexagonal filling arrangement, with a high filling rate.

[0020] In this case, for each of the bead cores 5, when, of the layers configuring the bead core 5, the maximum width of one of the layers including the maximum number of rows is W1, the width of another of the layers located on the innermost side in the tire radial direction is W1, and the width of another of the layers located on the outermost side in the tire radial direction is W2, the widths satisfy the relationships W1 > W2 and W2 ≤ 0.5 × W0. In addition, the layer having the maximum number of rows of the plurality of layers configuring the bead core 5 is located inward in the tire radial direction from the center position of the bead core 5.Specifically, each of the bead cores 5 is formed into a tapered shape such that the width of the bead core 5 decreases from a portion located inward in the tire radial direction from the center position in the tire radial direction and having the maximum width toward the outer side in the tire radial direction (such a shape may be referred to herein as a "radially outward side wedge shape"). Note that, as illustrated, each of the widths W0 to W2 is a length extending in the tire transverse direction and defined between the outer ends of the outer circumferential portions in the tire transverse direction located on opposite outer sides in the tire transverse direction of each of the layers.

[0021] The carcass layer 4 is folded back around the bead core 5 as described above. However, since the bead core 5 of the present invention has a special shape (the radially outward side wedge shape) as described above, the carcass layer 4 is bent along the circumference of the bead core 5. For example, in the illustrated example, the above-mentioned settings are satisfied by the bead core 5, and thus the cross-sectional shape is substantially pentagonal. Accordingly, the carcass layer 4 extending along the circumference of the bead core 5 is also bent into a substantially pentagonal shape.Furthermore, a portion of the folded-back portion 4B of the carcass layer 4, located outward in the tire radial direction from a radially outward end of the bead core 5, extends along the body portion 4A of the carcass layer 4 to each of the sidewall portions 2 while contacting the body portion 4A of the carcass layer 4. Consequently, the body portion 4A and the folded-back portion 4B of the carcass layer 4 form a closed region surrounding the bead core 5.

[0022] In one embodiment of the present invention, substantially only the bead core 5 is present in the closed region. In other words, even with the presence of insulating rubber covering the bead core 5A or rubber filling a small gap between the bead core 5 and the carcass layer 4, there is no bead filler with a large volume as in a prior art pneumatic tire. Specifically, the occupancy ratio of the rubber in the closed region, that is, the ratio of the total area a of the rubber present in the closed region to the area A of the closed region in the meridian cross-section (a / A × 100%), is from 0.1% to 15%.

[0023] Belt layers 6 of multiple layers (two layers in the illustrated example) are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each of the belt layers 6 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction. The reinforcing cords are arranged such that the reinforcing cords intersect between the layers. The belt layers 6 are set such that an inclination angle of the reinforcing cords with respect to the tire circumferential direction is in a range of, for example, 10° to 40°. Furthermore, belt reinforcing layers 7 are provided on the outer peripheral side of the belt layers 6. Specifically, in the illustrated example, two layers are provided: a full cover layer covering the entire width of the belt layers 6 and an edge cover layer covering only each end of the belt reinforcing layer 7.The belt reinforcing layers 7 include organic fiber cords oriented in the tire circumferential direction. The belt reinforcing layers 7 are set such that an angle of the organic fiber cords with respect to the tire circumferential direction is in a range of, for example, 0° to 5°.

[0024] A side reinforcing layer (8), which has a crescent shape in cross section, is arranged in the tire transverse direction inward of the carcass layer (4) in the sidewall portion (2). The side reinforcing layer 8 is made of rubber harder than other rubbers configuring the sidewall portion (2). Specifically, the rubber configuring the side reinforcing layer 8 has a JIS-A hardness of, for example, 70 to 80 and a modulus of, for example, 9.0 MPa to 10.0 MPa at 100% elongation. The side reinforcing layer 8 with such physical properties bears a load based on its rigidity and enables run-flat running when the tire is punctured.

[0025] A filler layer 9 is disposed outwardly of the carcass layer 4 (the body portion 4A and the folded-back portion 4B) in the sidewall portion 2 in the tire transverse direction. The filler layer 9 differs from a bead filler provided between the body portion 4A and the folded-back portion 4B of the carcass layer 4 in a prior art pneumatic tire in that the filler layer 9 is adapted to ensure the rigidity of the sidewall portion 2 in conjunction with the above-mentioned side reinforcing layer 8. Accordingly, the following relationships of the cross-sectional area S2 of the filler layer 9 and the hardness H2 of the filler layer 9 to the cross-sectional area S1 of the side reinforcing layer 8 and the hardness H1 of the side reinforcing layer 8 certainly satisfy the relationship 0.12 ≤ (S2 × H2) / (S1 × H1) ≤ 0.50.

[0026] As described above, the rubber occupancy rate in the closed region is small, from 0.1% to 15%, and only the bead core 5 is substantially present in the closed region. Thus, the tire weight can be reduced. In this case, the bead core 5 has the aforementioned shape, and the carcass layer 4 is folded back as described above. In addition, the side reinforcing layer 8 and the filler layer 9, which satisfy the relationship between the aforementioned cross-sectional areas and the aforementioned hardnesses, are provided. Accordingly, even in a case where a bead filler (or a tire component similar to the bead filler) is not substantially present between the body portion 4A and the folded back portion 4B of the carcass layer 4 as in a prior art tire, adequate rigidity can be ensured in a region near the bead portion 3.Thus, normal driving performance and run-flat performance can be advantageously maintained. Particularly, when the tire is mounted on a rim, the rim flange is in contact with the outer side of the bead portion 3, and the rigidity of a portion of the bead portion 3 in contact with the rim flange is ensured by the presence of the rim flange. Accordingly, the bead core 5 has the above-mentioned shape, and the carcass layer 4 is folded back as described above, and thus sufficient rigidity can be ensured even if the bead filler of the prior art is omitted. In addition, the above-mentioned filler layer 9 is provided, and thus sufficient rigidity can be securely achieved.It should be noted that the filler layer 9 is arranged outward in the tire transverse direction of the body portion 4A and the folded-back portion 4B of the carcass layer 4 as described above and satisfies the relationship between the above-mentioned cross-sectional areas and the above-mentioned hardnesses, that the filler layer 9 is different from the prior art bead filler in that the filler layer 9 can effectively increase the rigidity of the area near the bead portion 3 without being a member that increases the tire weight.

[0027] In the above structure, if the widths W0, W1, and W2 do not satisfy the relationships described above, the shape of the bead core 5 is unsuitable, and thus the shape of the bead portion 3 cannot be stabilized. Specifically, if the relationships W1≤W2 and W2>0.5×W0 exist, the width of an upper end of the bead core 5 is increased. Accordingly, unless a bead filler (or a tire component similar to the bead filler) is used, the carcass layer 4 is significantly bent around the bead core 5, and no effect of reducing the tire weight while ensuring rigidity is achieved. If the rubber occupancy ratio in the closed region is more than 15%, the tire is essentially the same as a prior art pneumatic tire with a bead filler, and thus it is difficult to reduce the tire weight.It should be noted that since an insulating rubber or the like covering the bead core 5A is always present in the tire structure, the occupancy ratio of the rubber in the closed region is basically not less than 0.1%. If the cross-sectional area and hardness of the side reinforcing layer 8 and the cross-sectional area and hardness of the filler layer 9 do not satisfy the relationship described above, the rigidity of the bead portion 3 cannot be adequately ensured. In particular, if (S2 × H2) / (S1 × H1) < 0.12, the rigidity of the bead portion 3 is insufficient, and thus rim separation is likely to occur. If (S2 × H2) / (S1 × H1) > 0.50, the rigidity of the bead portion 3 is excessively high, which may impair the basic mileage of the tire.

[0028] The specific shape of the bead core 5 is not particularly limited as long as the widths W0, W1 and W2 satisfy the relationships described above. For example, the widths shown in Fig. 3 and Fig. 4 illustrated forms. In the examples of Fig. 3 and Fig. 4, each of the widths W0, W1 and W2 satisfies the relationships described above, and thus the “radially outward side wedge shape” of the present invention applies. In particular, in Fig. 3A, a multiple stacking in the form of a trefoil with a 3 + 4 + 3 + 2 + 1 structure is provided. In Fig. 3B, a multiple stacking in the form of a trefoil of a 3 + 4 + 3 + 2 structure is provided. In Fig. 3C is a multiple stacking in the form of a trefoil of a 4 + 5 + 4 + 3 + 2 + 1 structure provided in Fig. 3D is a multi-stack in the form of a trefoil of a 3 + 4 + 4 + 3 + 2 + 1 structure. In addition, Fig. 4A a multiple stacking in the form of a trefoil of a 5 + 4 + 3 + 2 + 1 structure is provided and in Fig. 4B, a multiple stacking in the form of a trefoil of a 4 + 4 + 3 + 2 + 1 structure is provided. In Fig. 4C, a 4 + 4 + 3 + 2 + 1 structure is provided in which the layer located on the innermost side in the tire radial direction and the layer adjacent to the layer located on the innermost side in the tire radial direction are stacked in series (in a stacking manner such that the circumferential portions adjacent to each other in the tire radial direction are stacked vertically in the tire transverse direction).

[0029] In each of the Fig. 3 and Fig.4, at least a portion of the bead wire 5A is stacked multiple times in the form of a trefoil, and thus the bead wire 5A can be densely arranged, and the filling rate of the bead wire 5A is increased compared to a series-stacked bead wire as a whole. As a result, the rigidity and pressure resistance of the bead portion 3 can be adequately ensured, and the weight of the tire can be reduced while maintaining the mileage, and thus such performances can be achieved in a balanced manner. With regard to the filling rate of the bead wire 5A, all the bead wires 5A are preferably in the form of a trefoil as shown in Fig. 3A to 3D and Fig. 4A to 4B stacked multiple times.

[0030] Furthermore, for the shape of the bead core 5, when a polygonal shape formed by common tangent lines (dashed lines in the diagram) of the plural circumferential portions of the bead wire 5A in the meridian cross section is defined as an outer shape of the bead wire 5A, at least one of the internal angles of the corner portions located at opposite ends of a side of the outer shape located inward in the tire radial direction is preferably equal to or larger than 90°. This can prevent the arrangement of the bead wire 5A from being disturbed during vulcanization, and the bead core 5 can have a good shape after vulcanization, which is advantageous for reducing tire weight while ensuring excellent rigidity.When the inner angle α is less than 90°, portions of the bead core 5A located at the opposite ends of the outer mold side inward in the tire radial direction are easily affected by rubber flow during vulcanization, and thus it is difficult to maintain the bead core 5 in a good shape after vulcanization. From this perspective of the outer shape, the bead core 5 is preferably formed into a shape as shown in FIG. Fig. 3A to 3D and Fig. 4B to 4C, and in particular, the bead core 5 is preferably formed in a shape as shown in Fig. 3A to 3D and Fig. 4C illustrates.

[0031] In order to increase the stability of the overall shape of the bead core 5, the overall shape of the bead core 5 is preferably designed to be linearly symmetrical in the tire transverse direction with respect to the center of the bead core 5. From this perspective, the shapes are as in Fig. 3A to 3C and Fig. 4A and Fig. 4C preferred.

[0032] The above-mentioned various shapes of the bead cores 5 can be appropriately selected based on the above-mentioned various perspectives, taking into account the overall structure of the pneumatic tire or taking into account the features to be emphasized.

[0033] Since the pneumatic tire according to an embodiment of the present invention substantially does not contain bead filler as described above, the curved shape of the carcass layer 4 can be easily determined. Accordingly, the structure of the carcass layer 4 suitable for a runflat tire and the shape and arrangement of the appropriate side reinforcing layer 8 obtained by the carcass structure can be easily configured. For example, when the tire is mounted on a regular rim and inflated to a regular internal pressure, the rim width BW and the maximum width of the tire inner surface IW preferably satisfy the relationship 0.95 ≤ IW / BW ≤ 1.20. The rim width BW is set to be equal to the maximum width of the tire inner surface IW as just described, and thus the side reinforcing layer 8 can be formed into a good shape, and the runflat performance can be improved.Please note that the rim is not illustrated in the diagrams and only the dimension line indicating the rim width BW is shown.

[0034] In the Fig. In the embodiment illustrated in FIG. 1, one end of the folded-back portion 4B of the carcass layer 4 is in contact with the filler layer 9. In other words, the carcass layer 4 (the folded-back portion 4B) ends in a region where the filler layer 9 is present. With such a structure, the end of the folded-back portion 4B, which is likely to be the origin of breakage, can be prevented from being stressed, which is advantageous for improving tire durability. In addition, with such a structure, the length of the folded-back portion 4B of the carcass layer 4 can be reduced and the amount of the carcass layer 4 used can be minimized, and thus, it is also effective for reducing tire weight.

[0035] Of course, as in a Fig. 5, the folded-back portion 4B of the carcass layer 4 may be extended beyond the region where the filler layer 9 is present, and the end of the folded-back portion 4B of the carcass layer 4 may be arranged outward of the filler layer 9 in the tire radial direction. In this case, in a region where the body portion 4A and the folded-back portion 4B of the carcass layer 4 overlap, the reinforcing effect by the carcass layer 4 increases. Thus, even if the volume of the side reinforcing layer 8 is reduced as illustrated, the same rigidity as that of the side reinforcing layer 8 shown in FIG. Fig.1 or the like. Therefore, an increase in mass due to increasing the amount of the carcass layer 4 used can be compensated for by reducing the amount of the side reinforcing layer 8 used, and thus an influence on tire weight reduction can be minimized.

[0036] In the present invention, since the side reinforcing layer 8 and the filler layer 9 are provided, the sidewall portion 2 tends to be completely thick. Accordingly, the total thickness T1 in the tire axial direction of the sidewall portion 2 located at the tire maximum width position and the minimum value T2 of the total thickness in the tire axial direction of the sidewall portion 2 located in the area where the filler layer 9 is present satisfy the relationship 0.7 ≤ T2 / T1 ≤ 1.1. The thickness of each component is set as just described, and thus the tire shape from the tire maximum width position to the bead portion 3 can be favorably formed, which is advantageous for reducing the tire weight while ensuring excellent rigidity.When the ratio T2 / T1 is less than 0.7, the total thickness of the sidewall portion 2 in the tire axial direction, which is located in the area where the filler layer 9 is present, is relatively small, making it difficult to sufficiently ensure the durability of the bead portion 3. When the ratio T2 / T1 is greater than 1.1, the thickness of the sidewall portion 2 is completely increased, making it difficult to sufficiently reduce the tire weight.

[0037] Furthermore, regarding the structure of the side reinforcing layer 9, a height h0 of the side reinforcing layer 9 from the bead toe position, a height h1 from the bead toe position to a position where a thickness Tmax of the filler layer 9 is maximum, and a height h2 from the bead toe position to the end of the folded-back portion 4B of the carcass layer 4 satisfy the relationships h1 > h2 and 0.15 ≤ h1 / h0 ≤ 0.45. Thereby, the tire shape in the region where the filler layer 9 is present is further improved, which is advantageous for reducing the tire weight while ensuring excellent rigidity.

[0038] In a Fig. 6, the side reinforcing layer 8 does not extend to a position near an end of the carcass layer 4 which is located inward in the tire radial direction, as in the embodiment of Fig.1, and an end portion of the side reinforcing layer 8 located inward in the tire radial direction is located at a central portion of the filler layer 9 in the tire radial direction. In other words, when the sidewall portion 2 is viewed in the tire transverse direction, a region is formed in which only the carcass layer 4 and the filler layer 9 are present and the side reinforcing layer 8 is not present inward of the carcass layer 4 in the tire transverse direction.In this case, the length L1 along the carcass layer 4 of a region where the side reinforcing layer 8 and the filler layer 9 are overlapped with the carcass layer 4 in a state where the carcass layer 4 is disposed between the side reinforcing layer 8 and the filler layer 9, and the length L2 along the carcass layer 4 of a region where the body portion 4A and the folded-back portion 4B of the carcass layer 4 are in contact preferably satisfy the relationship 1 ≤ L1 / L2 ≤ 5.The positional relationships between the folded-back portion 4B of the carcass layer 4, the side reinforcing layer 8, and the filler layer 9 are appropriately determined as just described. Thus, in order to reduce tire weight while maintaining excellent rigidity, appropriate flexibility can be applied in a region from the sidewall 2 to a location near the bead portion 3, and ride comfort can be improved. In this case, if the ratio L1 / L2 is less than 1, the side reinforcing layer 8 and the filler layer 9 are not sufficiently overlapped, making it difficult to ensure adequate rigidity. If the ratio L1 / L2 is greater than 5, the side reinforcing layer 8 and the filler layer 9 are largely overlapped, and the rigidity of the sidewall portion 2 increases, and thus, the effect of applying flexibility cannot be sufficiently expected.

[0039] The structures of the respective components described above can be combined and applied accordingly. In any case, in the pneumatic tire structured as described above, the structure of the bead portion 3 is improved, and thus the tire can be reduced in weight while maintaining durability. Example

[0040] Thirty-six types of pneumatic tires were manufactured according to Prior Art Example 1, Comparative Examples 1 to 4, and Examples 1 to 31. Each of the pneumatic tires had a tire size of 205 / 55R16 and the Fig.1, and was determined as listed in Tables 1 to 4 for: the presence or absence of the bead filler disposed between the body portion and the folded-back portion of the carcass layer, the presence or absence of the filler layer disposed outward of the body portion and the folded-back portion of the carcass layer in the tire transverse direction, the structure of the bead core, the maximum width W0 of the bead core, the width W1 of the innermost layer of the bead core in the tire radial direction, the width W of the outermost layer of the bead core in the tire radial direction, the size ratio between the widths W1 and W2, the ratio W2 / W0, the occupancy ratio of rubber in the closed region, the cross-sectional area S1 and the hardness H1 of the side reinforcing layer, the cross-sectional area S2 and the hardness H2 of the filler layer, (S2 × H2) / (S1 × H1),the position of the end of the folded-back portion of the carcass layer, the ratio IW / BW of the maximum width IW of the tire inner surface to the rim width BW when the tire is mounted on a regular rim and inflated to a regular internal pressure, the internal angles θ of the corner portions located at the opposite ends of one side of the outer shape of the bead wire located inward in the tire radial direction, the ratio T2 / T1 of the minimum value T2 of the total thickness in the tire axial direction of the sidewall portion located in the area where the filler layer is present to the total thickness T1 in the tire axial direction of the sidewall portion located at the tire maximum width position, the height h0 of the side reinforcing layer from the bead toe position, the height h1 from the bead toe position to a position where the thickness Tmax of the filler layer is maximum,the height h2 from the bead toe position to the end of the folded-back portion of the carcass layer, the size ratio between the heights h1 and h2, the ratio h1 / h0 and the ratio L1 / L2 of the length L1 along the carcass layer of a region where the side reinforcing layer and the filler layer are overlapped with the carcass layer in a state where the carcass layer is disposed between the side reinforcing layer and the filler layer, to the length L2 along the carcass layer of a region where the body portion and the folded-back portion of the carcass layer are in contact.

[0041] The numbers of the diagrams indicating the corresponding structure are indicated in the columns of “Bead Core Structure” in Tables 1 to 4. However, for Prior Art Example 1, all the bead wires are layered in series to form a 5 + 5 + 5 + 5 structure, and thus, “5 + 5 + 5 + 5” is indicated in the table. Furthermore, since Comparative Example 3 has a structure in which the top and bottom surfaces of the bead core are Fig. 2 are reversed, “ Fig.2 (reverse)". For the columns "Position of the End of the Folded-Back Portion" in Tables 1 to 3, in a case where the end of the folded-back portion is located in the area where the filler layer is present, "side of the filler" is indicated, and in a case where the end of the folded-back portion is located outward of the outer end of the filler layer in the tire radial direction, "outward of the filler" is indicated. However, in Example 1 of the Prior Art, no filler layer is provided, but the bead filler is provided, and the end of the folded-back portion is located outward of the bead filler in the tire radial direction, and thus "outward of the bead filler" is indicated.The interior angle θ of each of the corner portions located at the opposite ends of one side of the outer shape of the bead wire located inward in the tire radial direction is also given in the “Interior angle θ” columns of Tables 1 to 3.

[0042] For the pneumatic tires, tire mass and runflat durability were evaluated according to the evaluation procedures described below. The evaluation results are also presented in Tables 1 to 4. Tire mass

[0043] For each test tire, the masses of five tires were measured, and an average tire value was calculated. The evaluation results were expressed as index values, with the prior art example 1 assigned an index value of 100. Smaller index values indicate lower tire masses. Emergency running durability

[0044] Each of the test tires was mounted on a wheel with a rim size of 16 × 6.5 J and run on a drum tester under drum durability test conditions for run-flat tires described in ECE 30, measuring the running distance until the tire was damaged or broken. The evaluation results were expressed as index values, with the prior art example 1 assigned an index value of 100. Larger index values indicate higher run-flat durability. [Table 1-I] Example of the prior art 1 Comparison example 1 Example 1 Example 2 Example 3 Presence / absence of bead filler Yes No No No No Presence / absence of filler layer No Yes Yes Yes Yes Tire bead core structure 5 + 5 + 5 + 5 Fig. 2 Fig. 2 Fig. 2 Fig. 2 W0 mm 4,0 7,0 7,0 7,0 7,0 W1 mm 4,0 5,5 5,5 5,5 5,5 W2 mm 4,0 3,0 3,0 3,0 3,0 Size ratio W1 = W2 W1 > W2 W1 > W2 W1 > W2 W1 > W2 W2 / W0 1 0,43 0,43 0,43 0,43 Rubber covering % 350 7 7 7 7 S1 mm2 - 720 720 580 520 H1 - 78 78 78 78 S2 mm2 - 90 128 138 195 H2 - 70 71 82 84 (S2 × H2) / (S1 × H1) - 0,11 0,16 0,25 0,40 Position of the end of the folded-back section d Away from the bead filler Side of the filler Side of the filler Side of the filler Side of the filler IW / BW 1,18 1,00 1,10 1,05 1,00 Interior angle θ ◯ 90 90 120 120 120 120 120 120 120 120 T2 / T1 1,05 0,72 0,78 0,85 0,87 h0 mm 96 96 96 96 96 h1 mm - 28 30 35 38 h2 mm 55 26 24 24 24 Size ratio - h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 / h0 - 0,29 0,31 0,36 0,4 L1 / L2 - 3,3 3,3 2,9 2,8 Tire mass Index value 100 97 99 98 98 Emergency running durability Index value 100 96 106 104 108 [Table 1-II] Example 4 Comparison example 2 Comparison example 3 Example 5 Presence / absence of bead filler No No No No Presence / absence of filler layer Yes Yes Yes Yes Tire bead core structure Fig. 2 Fig. 2 Fig. 2 (reverse) Fig. 2 W0 mm 7,0 7,0 7,0 7,0 W1 mm 5,5 5,5 3,0 5,5 W2 mm 3,0 3,0 5,5 3,0 Size ratio W1 > W2 W1 > W2 W1 < W2 W1 > W2 W2 / W0 0,43 0,43 0,79 0,43 Rubber covering % 7 7 7 0,1 S1 mm 2 500 450 580 580 H1 74 72 78 78 S2 mm 2 210 210 138 138 H2 88 94 82 82 (S2 × H2) / (S1 × H1) 0,50 0,61 0,25 0,25 Position of the end of the folded back section Side of the filler Side of the filler Side of the filler Side of the filler IW / BW 0,97 0,95 1,05 1,05 Interior angle θ ◯ 120 120 120 120 120 120 120 120 T2 / T1 0,9 1,00 0,85 0,85 h0 mm 96 96 96 96 h1 mm 40 43 28 28 h2 mm 22 20 23 23 Size ratio h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 / h0 0,42 0,45 0,29 0,29 L1 / L2 2,7 2,5 2,9 2,9 Tire mass Index value 98 97 98 98 Emergency running durability Index value 104 98 92 104 [Table 2-I] Example 6 Comparison example 4 Example 7 Example 8 Example 9 Presence / absence of bead filler No No No No No Presence / absence of filler layer Yes Yes Yes Yes Yes Tire bead core structure Fig. 2 Fig. 2 Fig. 3A Fig. 3B Fig. 3C W0 mm 7,0 7,0 5,5 5,5 7,0 W1 mm 5,5 5,5 4,2 4,2 5,5 W2 mm 3,0 3,0 1,4 3,0 1,4 Size ratio W1 > W2 W1 > W2 W1 > W2 W1 > W2 W1 > W2 W2 / W0 0,43 0,43 0,25 0,55 0,2 Rubber covering % 15 20 7 7 7 S1 mm 2 580 580 580 580 580 H1 78 78 78 78 78 S2 mm 2 138 138 138 138 138 H2 82 82 82 82 82 (S2 × H2) / (S1 × H1) 0,25 0,25 0,25 0,25 0,25 Position of the end of the folded back section Side of the filler Side of the filler Side of the filler Side of the filler Side of the filler IW / BW 1,05 1,05 1,00 1,00 1,00 Interior angle θ ◯ 120 120 120 120 120 120 120 120 120 120 T2 / T1 0,85 0,85 0,85 0,85 0,85 h0 mm 96 96 96 96 96 h1 mm 28 28 35 35 35 h2 mm 23 23 23 23 23 Size ratio h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 / h0 0,29 0,29 0,36 0,36 0,36 L1 / L2 2,9 2,9 2,9 2,9 2,9 Tire mass Index value 98 99 96 96 96 Emergency running durability Index value 104 98 106 106 106 [Table 2-II] Example 10 Example 11 Example 12 Example 13 Example 14 Presence / absence of bead filler No No No No No Presence / absence of filler layer Yes Yes Yes Yes Yes Tire bead core structure Fig. 3D Fig. 4A Fig. 4B Fig. 4C Fig. 2 W0 mm 5,5 7,0 5,5 5,5 7,0 W1 mm 4,2 7,0 5,5 5,5 5,5 W2 mm 1,4 1,4 1,4 1,4 3,0 Size ratio W1 > W2 W1 > W2 W1 > W2 W1 > W2 W1 > W2 W2 / W0 0,25 0,2 0,25 0,25 0,43 Rubber covering % 7 7 7 7 7 S1 mm 2 580 580 580 580 580 H1 78 78 78 78 78 S2 mm 2 138 138 138 138 138 H2 82 82 82 82 82 (S2 × H2) / (S1 × H1) 0,25 0,25 0,25 0,25 0,25 Position of the end of the folded back section Side of the filler Side of the filler Side of the filler Side of the filler Away from the filler IW / BW 1,00 1,00 1,00 1,00 1,00 Interior angle θ ◯ 120 60 120 90 120 120 60 60 90 120 T2 / T1 0,85 0,85 0,85 0,85 0,85 h0 mm 96 96 96 96 96 h1 mm 35 35 35 35 35 h2 mm 23 23 23 23 50 Size ratio h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 < h2 h1 / h0 0,36 0,36 0,36 0,36 0,36 L1 / L2 2,9 2,9 2,9 2,9 2,9 Tire mass Index value 96 96 96 96 97 Emergency running durability Index value 106 102 102 103 104 [Table 3-I] Example 15 Example 16 Example 17 Example 18 Presence / absence of bead filler No No No No Presence / absence of filler layer Yes Yes Yes Yes Tire bead core structure Fig. 2 Fig. 2 Fig. 2 Fig. 2 W0 mm 7,0 7,0 7,0 7,0 W1 mm 5,5 5,5 5,5 5,5 W2 mm 3,0 3,0 3,0 3,0 Size ratio W1 > W2 W1 > W2 W1 > W2 W1 > W2 W2 / W0 0,43 0,43 0,43 0,43 Rubber covering % 7 7 7 7 S1 mm 2 580 580 580 580 H1 78 78 78 78 S2 mm 2 138 138 138 138 H2 82 82 82 82 (S2 × H2) / (S1 × H1) 0,25 0,25 0,25 0,25 Position of the end of the folded back section Side of the filler Side of the filler Side of the filler Side of the filler IW / BW 0,95 1,1 1,15 1,2 Interior angle θ ◯ 120 120 120 120 120 120 120 120 T2 / T1 0,85 0,85 0,85 0,85 h0 mm 96 96 96 96 h1 mm 35 35 35 35 h2 mm 23 23 23 23 Size ratio h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 / h0 0,36 0,36 0,36 0,36 L1 / L2 2,9 2,9 2,9 2,9 Tire mass Index value 96 96 96 96 Emergency running durability Index value 106 105 102 101 [Table 3-II] Example 19 Example 20 Example 21 Example 22 Presence / absence of bead filler No No No No Presence / absence of filler layer Yes Yes Yes Yes Tire bead core structure Fig. 2 Fig. 2 Fig. 2 Fig. 2 W0 mm 7,0 7,0 7,0 7,0 W1 mm 5,5 5,5 5,5 5,5 W2 mm 3,0 3,0 3,0 3,0 Size ratio W1 > W2 W1 > W2 W1 > W2 W1 > W2 W2 / W0 0,43 0,43 0,43 0,43 Rubber covering % 7 7 7 7 S1 mm2 710 720 550 500 H1 78 78 74 74 S2 mm2 130 120 200 210 H2 71 71 88 88 (S2 × H2) / (S1 × H1) 0,17 0,15 0,43 0,5 Position of the end of the folded back section Side of the filler Side of the filler Side of the filler Side of the filler IW / BW 1,00 1,00 1,00 1,00 Interior angle θ ◯ 120 120 120 120 120 120 120 120 T2 / T1 0,7 0,75 1,1 1,2 h0 mm 96 96 96 96 h1 mm 35 35 35 35 h2 mm 23 23 23 23 Size ratio h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 / h0 0,36 0,36 0,36 0,36 L1 / L2 2,9 2,9 2,9 2,9 Tire mass Index value 99 99 98 98 Emergency running durability Index value 101 102 107 106 [Table 4-I] Example 23 Example 24 Example 25 Example 26 Example 27 Presence / absence of bead filler No No No No No Presence / absence of filler layer Yes Yes Yes Yes Yes Tire bead core structure Fig. 2 Fig. 2 Fig. 2 Fig. 2 Fig. 2 W0 mm 7,0 7,0 7,0 7,0 7,0 W1 mm 5,5 5,5 5,5 5,5 5,5 W2 mm 3,0 3,0 3,0 3,0 3,0 Size ratio W1 > W2 W1 > W2 W1 > W2 W1 > W2 W1 > W2 W2 / W0 0,43 0,43 0,43 0,43 0,43 Rubber covering % 7 7 7 7 7 S1 mm 2 580 700 500 500 500 H1 78 78 74 74 74 S2 mm 2 138 20 46 210 210 H2 82 96 98 88 88 (S2 × H2) / (S1 × H1) 0,25 0,04 0,12 0,5 0,5 Position of the end of the folded back section Side of the filler Side of the filler Side of the filler Side of the filler Side of the filler IW / BW 1,00 1,00 1,00 1,00 1,00 Interior angle θ ◯ 120 120 120 120 120 120 120 120 120 120 T2 / T1 0,85 0,85 0,85 0,85 0,85 h0 mm 96 98 98 96 96 h1 mm 35 13 15 43 48 h2 mm 40 12 14 23 23 Size ratio h1 < h2 h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 / h0 0,36 0,13 0,15 0,45 0,5 L1 / L2 1,3 4,3 4,5 2,9 2,9 Tire mass Index value 98 99 97 98 98 Emergency running durability Index value 106 101 102 102 101 [Table 4-II] Example 28 Example 29 Example 30 Example 31 Presence / absence of bead filler No No No No Presence / absence of filler layer Yes Yes Yes Yes Tire bead core structure Fig. 2 Fig. 2 Fig. 2 Fig. 2 W0 mm 7,0 7,0 7,0 7,0 W1 mm 5,5 5,5 5,5 5,5 W2 mm 3,0 3,0 3,0 3,0 Size ratio W1 > W2 W1 > W2 W1 > W2 W1 > W2 W2 / W0 0,43 0,43 0,43 0,43 Rubber covering % 7 7 7 8 S1 mm 2 580 580 580 580 H1 78 78 78 78 S2 mm 2 138 138 138 138 H2 82 82 82 82 (S2 × H2) / (S1 × H1) 0,25 0,25 0,25 0,25 Position of the end of the folded back section Side of the filler Side of the filler Side of the filler Side of the filler IW / BW 1,00 1,00 1,00 1,00 Interior angle θ ◯ 120 120 120 120 120 120 120 120 T2 / T1 0,85 0,85 0,85 0,85 h0 mm 96 96 96 96 h1 mm 43 35 35 40 h2 mm 42 30 22 19 Size ratio h1 > h2 h1 > h2 h1 > h2 h1 > h2 h1 / h0 0,45 0,36 0,36 0,42 L1 / L2 0,5 1 5 6 Tire mass Index value 98 98 98 98 Emergency running durability Index value 102 106 105 102

[0045] As can be seen from Table 1, in each of Examples 1 to 31, the tire mass was reduced while the runflat durability was maintained or improved compared to Prior Art Example 1. On the other hand, in Comparative Example 1, the value of (S2 × H2) / (S1 × H1) was too small, so the runflat durability and steering stability deteriorated. In Comparative Example 2, the value of (S2 × H2) / (S1 × H1) was too large, and thus the runflat durability and ride comfort performance deteriorated. In Comparative Example 3, the width W2 was larger than the width W1, and thus the runflat durability deteriorated. In Comparative Example 4, the occupancy ratio of the rubber in the closed region was too large, and thus the effect of reducing tire weight could not be sufficiently achieved. List of reference symbols 1 tread section 2 side wall section 3 bead section 4 carcass layers 5 Bead core 6 belt layer 7 Belt reinforcement layer 8 side reinforcement layer 9 filler layer CL Tire Equator

Claims

[1] Pneumatic tyres comprising: a tread portion (1) extending in a tire circumferential direction and having a ring shape; a pair of sidewall portions (2) arranged on opposite sides of the tread portion (1); a pair of bead portions (3) arranged inwardly of the sidewall portions (2) in the tire radial direction; a bead core (5) provided in each of the bead portions (3); a carcass layer (4) disposed between the pair of tire bead portions (3); and a side reinforcing layer (8) provided in the tire transverse direction inward of the carcass layer (4) in the sidewall portion (2) and having a crescent shape in cross section; where the bead core (5) comprises at least one bead wire (5A) wound in the tire circumferential direction, a plurality of circumferential portions of the bead wire (5A) form at least one row arranged in the tire transverse direction and a plurality of layers overlapping in the tire radial direction, a width W0 of one of the plurality of layers including a maximum number of rows, a width W1 of another of the plurality of layers located on the innermost side in the tire radial direction, and a width W2 of another of the plurality of layers located on the outermost side in the tire radial direction satisfy the relationships W1 > W2 and W2 ≤ 0.5 × W0, the layer of the plurality of layers including the maximum number of rows is located inward in the tire radial direction from the center position of the bead core (5) in the tire radial direction, the carcass layer (4) includes a body portion (4A) extending from the tread portion (1) through each of the sidewall portions (2) to each of the bead portions (3), and a folded-back portion (4B) folded at each of the bead portions (3) and curved along a circumference of the bead core (5) and extending to each of the sidewall portions (2) while contacting the body portion (4A) from an outer end position of the bead core (5) in the tire radial direction, a ratio of a total area of the rubber present in a closed region to an area of the closed region formed by the body portion (4A) and the folded-back portion (4B) of the carcass layer (4) is 0.1% to 15%, a filler layer (9) is provided in the tire transverse direction outward of the body portion (4A) and the folded-back portion (4B) of the carcass layer (4), and a cross-sectional area S1 of the side reinforcement layer (8) and a hardness H1 of the side reinforcement layer (8) as well as a cross-sectional area S2 of the filler layer (9) and a hardness H2 of the filler layer (9) satisfy a relationship 0.12 ≤ (S2 × H2) / (S1 × H1) ≤ 0.

50. [2] A pneumatic tire according to claim 1, wherein one end of the folded-back portion (4B) of the carcass layer (4) is in contact with the filler layer (9). [3] A pneumatic tire according to claim 1 or 2, wherein, when the tire is mounted on a regular rim and inflated to a regular inner pressure, a rim width BW and a maximum width of the tire inner surface IW satisfy a relationship of 0.95 ≤ IW / BW ≤ 1.

20. [4] A pneumatic tire according to any one of claims 1 to 3, wherein at least a portion of the bead wire (5A) is layered so that the bead core (5) has a trefoil shape. [5] A pneumatic tire according to any one of claims 1 to 4, wherein, when a polygon formed by common tangent lines of a plurality of circumferential portions of the bead wire (5A) in a meridian cross section is defined as an outer shape of the bead wire (5A), an inner angle (θ) of at least one of corner portions located at ends of the outer shape arranged inward in the tire radial direction is equal to or larger than 90°. [6] A pneumatic tire according to any one of claims 1 to 5, wherein a total thickness T1 in the tire axial direction of the sidewall portion (2) located at a tire maximum width position and a minimum value T2 of a total thickness in the tire axial direction of the sidewall portion (2) located in a region where the filler layer (9) is present satisfy a relationship of 0.7 ≤ T2 / T1:51.

1. [7] A pneumatic tire according to any one of claims 1 to 6, wherein a height h0 of the side reinforcing layer (8) from a bead toe position, a height h1 from the bead toe position to a position where the thickness of the filler layer (9) is maximum, and a height h2 from the bead toe position to an end of the folded-back portion (4B) of the carcass layer (4) satisfy the relationships h1 > h2 and 0.15 ≤ h1 / h0 ≤ 0.

45. [8] A pneumatic tire according to any one of claims 1 to 7, wherein a length L1 along the carcass layer (4) of a region where the side reinforcing layer (8) and the filler layer (9) are overlapped in a state where the carcass layer (4) is disposed between the side reinforcing layer (8) and the filler layer (9), and a length L2 along the carcass layer (4) of a region where the body portion and the folded-back portion (4B) of the carcass layer (4) are in contact satisfy the relationship 1 ≤ L1 / L2 ≤ 5.

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