pneumatic tires

Abstract

Pneumatic tires (1), comprising: Bead cores (11) formed by ring-shaped and multi-layered winding of one or a plurality of bead wires (111); a carcass layer (13) formed from a carcass layer of a single layer or a plurality of layers, wherein the carcass layer (13) is folded over to wrap around the bead cores (11) and extends between the bead cores (11); a wheel rim pad rubber (17) arranged along a folded-over section (132) of the carcass layer (13) to form a rim mating surface of a bead section; wherein the folded-over section (132) of the carcass layer (13) contacts a body section (131) of the carcass layer (13) in a cross-sectional view in a tire meridian direction to form a closed area (X) surrounding the bead cores (11); a rubber covering ratio in the closed area (X) is in a range of 15% or less, wherein the rubber covering ratio in the cross-sectional view in the tire meridian direction is calculated as the ratio of the cross-sectional area of ​​the rubber material in the closed area (X) to the total cross-sectional area of ​​the closed area (X); the bead cores (11) have a predetermined wire arrangement structure formed by arranging wire cross-sections of the bead wires (111) in the cross-sectional view in the tire meridian direction; a tangent line L1, contact points C1, C2, a midpoint Cm of the contact points C1, C2 and a thickness Gm are defined, wherein the tangent line L1 contacts an innermost wire layer in a tire radial direction and the wire cross-sections are located at the innermost and outermost points in a tire transverse direction in the wire arrangement structure from the rim fitting surface side, wherein the contact points C1, C2 of the tangent line L1 are located at the innermost and outermost points on the wire cross-sections, and wherein the thickness Gm extends in the tire radial direction from the midpoint Cm to the rim fitting surface; a rate of change ΔGm of thickness Gm between a state before and after mounting on a rim in a range of 10% or more to 60% or less; In the cross-sectional view in the tire meridian direction, a bead base (Bb) of the rim mating surface is formed by connecting two types of linear sections with different angles of inclination, an extension line L2 of the linear section on a bead heel side and an extension line L3 of the linear section on a bead toe side of the bead base (Bb) of the rim mating surface are defined, and The inclination angles α, β of the extension lines L2 and L3 with respect to the tangent line L1 must satisfy a ratio of 0 ≤ β / α ≤ 5.0.

Description

Technical field

[0001] The invention relates to a pneumatic tire and in particular to a pneumatic tire that can improve the rim fit of the tire while reducing the weight of the tire. State of the art

[0002] In recent years, efforts to reduce tire weight have focused on reducing the weight of the bead sections. A technology for a pneumatic tire, as described in the prior art, is known from JP 2008 149778 A. In JP 2008 149778 A, bead fillers are omitted to reduce the tire's weight.

[0003] Further tires are known from DE 39 36 231 A1, US 4 258 775 A and JP 2002-200905 A. Brief description of the invention: Technical problem

[0004] However, in the tire described above, a deterioration in the rim fit of the tire may occur due to the elimination of the bead fillers.

[0005] One object of the invention is to provide a pneumatic tire that can improve the rim fit of the tire while simultaneously reducing the weight of the tire. Solution to the problem

[0006] The problem is solved by a tire with the features of claim 1. Advantageous further developments are defined in the dependent claims. In an advantageous embodiment, a pneumatic tire includes bead cores, a carcass layer, and a rim pad rubber. The bead cores are formed by ring-shaped and multi-layer winding of one or a plurality of bead wires. The carcass layer is formed from a carcass ply consisting of a single layer or a plurality of layers. The carcass layer is folded over to wrap around the bead cores and extend between them. The rim pad rubber is arranged along a folded-over section of the carcass layer to form a rim mating surface for a bead section.The folded-over section of the carcass layer contacts a body section of the carcass layer in a cross-sectional view along a tire meridian direction to form a closed area surrounding the bead cores. The rubber layup ratio in the closed area is 15% or less. The bead cores have a predetermined wire arrangement structure formed by arranging wire cross-sections of the bead wires in the cross-sectional view along a tire meridian direction. A tangent line L1, contact points C1 and C2, a midpoint Cm of contact points C1 and C2, and a thickness Gm are defined. The tangent line L1 contacts an innermost layer in the tire radial direction and the innermost and outermost wire cross-sections in a tire transverse direction within the wire arrangement structure from the rim face. The contact points C1 and C2 of the tangent line L1 are located on the innermost and outermost wire cross-sections.The thickness Gm runs in the transverse direction of the tire from the center point Cm to the rim mounting surface. The rate of change ΔGm of the thickness Gm between the state before and after mounting on a rim ranges from 10% or more to 60% or less. Advantageous effects of the invention

[0007] In the pneumatic tire according to one embodiment of the invention (1), the rubber coverage ratio in the closed area, which is surrounded by the body section and the folded-over section of the carcass layer, i.e., a rubber volume around the bead cores, is set significantly low. Since bead fillers can thus be omitted, this has the advantageous effect of reducing the tire's weight. Furthermore (2), the advantage lies in the fact that the rate of change ΔGm of the rim fit section of the bead section is appropriately controlled. That is, the lower limit ensures the rim fit pressure and thus the rim fit of the tire. Moreover, the upper limit prevents a deterioration in the machinability of mounting the tire on the rim due to excessive rim fit pressure. Brief description of the drawings Fig. Figure 1 is a cross-sectional view in a tire meridian direction illustrating a pneumatic tire according to an embodiment of the invention. Fig. 2 is a cross-sectional view showing a bead section of the in Fig. 1 illustrated pneumatic tire. Fig. 3 is an enlarged view showing a rim pass section of the Fig. 2 illustrated bulge section. Fig. 4 is an explanatory diagram showing a wire arrangement structure of in Fig. 3 illustrated bead cores. Fig. Figure 5 is an explanatory diagram illustrating the rim pass section of the bead section in a state where the tire is mounted on a rim. Fig. 6 is an explanatory diagram that illustrates the Fig. 3 illustrated rim pass section illustrated. Fig. 7 is an explanatory diagram that illustrates the Fig. 3 illustrated rim pass section illustrated. Fig. Figure 8 is an explanatory diagram that shows a modified example of the one in Fig. 4 illustrated bead cores. Fig. 9 is an explanatory diagram that shows a modified example of the one in Fig. 4 illustrated bead cores. Fig. 10 is an explanatory diagram that shows a modified example of the one in Fig. 4 illustrated bead cores. Fig. 11 is an explanatory diagram of a modified example of the in Fig. 4 illustrated bead cores. Fig. 12 is an explanatory diagram that shows a modified example of the one in Fig. 4 illustrated bead cores. Fig. 13 is an enlarged view showing a tire sidewall section of the Fig. 1 illustrated pneumatic tire. Fig. Figure 14 is a table showing results of performance tests of pneumatic tires according to embodiments of the invention and a comparative example not belonging to the invention. Fig. Figure 15 is an explanatory diagram illustrating the bead cores of a test tire of a state-of-the-art example. Description of embodiments

[0008] Embodiments of the invention are described in detail below with reference to the drawings. However, the invention is not limited to these embodiments. Furthermore, components of the embodiments include elements that are interchangeable while maintaining conformity with the invention, as well as obviously interchangeable elements. Moreover, the modified examples described in the embodiments can be combined as needed within the scope of protection that is obvious to a person skilled in the art. pneumatic tires

[0009] Fig. Figure 1 is a cross-sectional view in a tire meridional direction, illustrating a pneumatic tire according to one embodiment of the invention. The same drawing illustrates a cross-sectional view of a half-section in the tire radial direction. Likewise, the same drawing illustrates a radial tire for a passenger car as an example of a pneumatic tire. Referring to the same drawing, "cross-section in a tire meridian direction" refers to a cross-section of the tire along a plane that includes the tire's axis of rotation (not shown). The reference symbol CL denotes the equatorial plane of the tire and refers to a plane perpendicular to the tire's axis of rotation, passing through the tire's center point in the direction of the tire's axis of rotation. "Tire transverse direction" refers to the direction parallel to the tire's axis of rotation. "Tire radial direction" refers to the direction perpendicular to the tire's axis of rotation. A pneumatic tire 1 has a ring-shaped structure with the tire rotation axis and includes a pair of bead cores 11, 11, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, a pair of rim pad rubbers 17, 17 and an inner core 18 (see Fig. 1).

[0010] The pair of bead cores 11, 11 is formed by ring-shaped and multi-layered winding of one or more steel bead wires. The pair of bead cores 11, 11 is embedded in bead sections to form the cores of the right and left bead sections.

[0011] The carcass layer 13 has a single-layer structure, formed from a single carcass ply, or a multi-layer structure, formed by layers of multiple carcass plies, and extends between the right and left bead cores 11, 11 in a torus shape, thus forming the support structure for the tire. Furthermore, both end sections of the carcass layer 13 are folded outwards in the transverse direction of the tire so that they are wrapped around the bead cores 11 and fixed in place. The carcass ply(s) of the carcass layer 13 are manufactured by a rolling process for coating onto a multitude of rubber-coated carcass cord threads made of steel or an organic fiber material (e.g., aramid, nylon, polyester, and rayon).The carcass ply(s) have a carcass angle (defined as an angle of inclination of a longitudinal direction of the carcass cord threads relative to the tire circumference) with a value in the range of 80 degrees or more to 90 degrees or less. Although the configuration of . Fig. 1. If the single layer structure is formed in which the carcass layer 13 is formed from a single carcass ply, no such restriction is provided, and the carcass layer 13 may have a multi-layer structure formed by layers of a multitude of carcass plies.

[0012] The belt layer 14 is formed by layering a pair of cross belts 141, 142, a belt cover 143, and a pair of belt edge covers 144, and arranging them to be wrapped around the circumference of the carcass layer 13. The pair of cross belts 141, 142 is produced by a rolling process on a plurality of rubber-coated belt cord threads made of steel or an organic fiber material. The cross belts 141, 142 have a belt angle ranging from 20 degrees or more to 55 degrees or less. Furthermore, the pair of cross belts 141, 142 has belt angles (defined as the inclination angle of the longitudinal direction of the belt cord threads relative to the tire circumference) with opposite signs, and the cross belts 141, 142 are layered such that the longitudinal directions of the belt cord threads intersect (so-called cross-ply structure).The belt cover 143 and the pair of belt edge covers 144 are manufactured by coating belt cover cord threads made of steel or an organic fiber material with a coating rubber and have belt angles of 0 degrees or more to 10 degrees or less. Furthermore, the belt cover 143 and the pair of belt edge covers 144 are, for example, a strip material formed by coating one or a plurality of belt cover cord threads with a coating rubber and repeatedly winding the strip material spirally around the outer circumferential surfaces of the cross belts 141, 142 in the tire circumferential direction.

[0013] The tread rubber 15 is arranged outside the carcass layer 13 and the belt layer 14 in the tire radial direction and forms a tread section of the tire. The pair of sidewall rubbers 16, 16 are arranged outside the carcass layer 13 in the tire transverse direction and form a right and a left sidewall section. The pair of respective rim pad rubbers 17, 17 are arranged inwards in the tire radial direction from the right and left tire bead core 11, 11 and the folded-over sections of the carcass layer 13 to form rim mating surfaces of the bead sections.

[0014] The inner liner 18 is an air-inhibiting layer arranged on the surface of the tire cavity and covering the carcass layer 13. The inner liner 18 also suppresses oxidation caused by exposure of the carcass layer 13 and prevents air from escaping the tire. Furthermore, the inner liner 18 consists, for example, of a rubber compound with butyl rubber as the main component, thermoplastic resin, a thermoplastic elastomer compound produced by mixing an elastomeric component with a thermoplastic resin, and the like. The inner liner 18 is bonded to the carcass layer 13 via a bonding rubber (not illustrated). Structure without bead filler

[0015] Fig. 2 is a cross-sectional view showing the bead section of the in Fig. Figure 1 illustrates the pneumatic tire. The same drawing illustrates a cross-sectional view of the bead section in the tire's meridional direction in a state before the tire is mounted on a rim.

[0016] As in Fig. As illustrated in Figure 2, the carcass layer 13 is folded outwards in the transverse direction of the tire so that it is wrapped around the bead cores 11 and fixed in place. At this point, a closed area X is formed around the bead cores 11 as the folded section 132 of the carcass layer 13 comes into contact with a body section 131. Furthermore, the closed area X extends around the entire circumference of the tire, and the tire forms a ring-shaped closed space surrounding the bead cores 11.

[0017] The closed area X is defined as an area surrounded in a cross-sectional view by the carcass ply of carcass layer 13 in the tire meridional direction. More precisely, the area surrounded by the surface of the coating rubber of the carcass ply is defined as the closed area X.

[0018] Likewise, in the configuration of Fig. 2. The carcass layer 13 is formed from the single-ply carcass layer, and the closed region X is formed by self-contact of the carcass layer. On the other hand, the carcass layer 13 is formed in a configuration from the multitude of layered carcass layers (not shown) that can be formed in a closed region X by mutual contact of the different carcass layers. For example, the following configuration (not shown) is assumed. The carcass layer 13 has a two-layer structure formed by layers of first and second carcass layers; a folded-over section of the first carcass layer ends at the midpoint of a radial height H1 (see Fig. 2) the bead cores 11 without contact with the body section, and a folded-over section of the second carcass layer extends radially outwards from the bead cores 11 and is in contact with the body section of the first carcass layer.

[0019] At this point, the rubber coverage ratio in the closed area X is preferably in the range of 15% or less, more preferably in the range of 10% or less, and even more preferably in the range of 5% or less. Accordingly, the rubber coverage ratio in the closed area X surrounded by the body section 131 and the folded-over section 132 of the carcass layer 13, that is, the rubber volume around the bead cores 11, is set very low. Thus, the objective of reducing the weight of the tire by omitting the bead filler is achieved. It should be noted that the lower limit of the rubber coverage ratio is not particularly restricted, but is preferably 0.1% or greater. Therefore, the amount of insulating rubber in the bead cores 11 is ensured in a suitable manner.

[0020] The rubber coverage ratio is calculated as a ratio (%) of the cross-sectional area of ​​the rubber materials in the closed area X to the total cross-sectional area of ​​the closed area X in the cross-sectional view in the tire meridian direction.

[0021] For example, in the configuration of Fig. 2. The folded section 132 of the carcass layer 13 is folded over without enclosing a bead filler in the closed area X and without being in contact with the body section 131. The carcass layer 13 is also wound along the outer circumferential surfaces of the bead cores 11. Thus, only the components of the bead cores 11 are present in the closed area X. The components of the bead cores 11 include bead wires 111, the insulating rubbers, bead covers, and winding turns.

[0022] It should be noted that the bead filler is a reinforcing rubber arranged to fill a triangular gap between the bead cores, the body section, and the folded-over section of the carcass ply, and it is arranged to increase the stiffness of the bead section. The bead filler generally has a triangular cross-section and a rubber hardness of 65 or higher to 99 or lower.

[0023] The rubber hardness is measured according to JIS K 6253.

[0024] Additionally, in the configuration described above, in which the bead filler has been omitted, as in Fig. As illustrated in Figure 2, the folded-over section 132 of the carcass layer 13 is preferably in surface contact with the body section 131 of the carcass layer 13 and is fixed. A radial height H2 of the contact section between the body section 131 and the folded-over section 132 of the carcass layer 13 preferably has a ratio of 0.80 ≤ H2 / H1 ≤ 3.00 to the radial height H1 of the bead cores 11, and more preferably has a ratio of 1.20 ≤ H2 / H1 ≤ 2.50. Accordingly, the radial height H2 of the self-contacting section of the carcass layer 13 is manufactured accordingly. In other words, the lower limit ensures that the folded-over section 132 comes into stable contact with the body section 131, thereby improving the durability of the bead section. Furthermore, the upper limit suppresses an increase in tire weight due to the excessive amount of the handled section 132.

[0025] The radial height H1 of the bead cores is measured as the maximum height in the tire radial direction from the innermost layer in the wire arrangement structure of the bead cores in the tire radial direction and the inner end in the tire transverse direction of the wire cross-section, which is at the outermost point in the tire transverse direction, to an outermost side in the tire radial direction and an outer end in the tire radial direction of the wire cross-section, which is at the outermost point in the tire transverse direction.

[0026] The radial height H2 in the self-contacting section of the carcass layer is measured as the maximum length of the contact section between the body section and the folded-over section of the carcass layer in the tire radial direction.

[0027] As in Fig. As illustrated in Figure 2, in the configuration described above, an additional end section (reference symbol omitted in the drawing) of the folded section 132 of the carcass layer 13 preferably contacts the body section 131 of the carcass layer 13. In such a configuration, the stress concentration at the end section of the folded section 132 is reduced compared to a configuration in which the end section of the folded section 132 is spaced apart from the body section 131 (not shown). Consequently, the separation of the circumferential rubber starting from the end section of the folded section 132 is suppressed.

[0028] The actual length La2 (dimension symbol omitted in the drawing) of the contact section between the body section 131 and the folded section 132 of the carcass layer 13 preferably fulfills a ratio of 0.30 ≤ La2 / La1 ≤ 2.00 to a circumferential length La1 (dimension symbol omitted in the drawing) of the closed area X, and more preferably fulfills a ratio of 0.37 ≤ La2 / La1 ≤ 1.80. Therefore, the actual length La2 of the self-contacting section of the carcass layer 13 is manufactured accordingly. That is, the lower limit appropriately ensures the spring properties of the carcass layer 13, it ensures steering stability on dry road surfaces, and it ensures the durability of the bead section. Furthermore, the upper limit prevents an increase in tire weight due to the excessive length of the folded section 132.

[0029] The circumferential length La1 of the closed area X is measured as a circumferential length of the surface of the carcass layer, which in the cross-sectional view in the tire meridian direction represents the boundary line of the closed area X.

[0030] The actual length La2 of the contact section is measured as a circumferential length of the self-contacting section between the body section and the folded-over section of the carcass layer in the cross-sectional view in the tire meridional direction. Outer reinforcement rubber

[0031] As in Fig. As illustrated in Figure 2, the pneumatic tire 1 includes an outer side reinforcement rubber 19 in addition to the sidewall rubber 16 and the wheel rim padding rubber 17 described above.

[0032] Each of the sidewall rubbers 16 is arranged outwards from the carcass layer 13 in the transverse direction of the tire and forms the sidewall sections of the tire described above. Additionally, the rubber hardness of the sidewall rubber 16 is in the range of 40 or more to 70 or less. Furthermore, the elongation at break of the sidewall rubber 16 is in the range of 400% or more to 650% or less.

[0033] The elongation at break is measured according to the JIS K6251 standard.

[0034] The rim pad rubber 17 is arranged such that it is positioned inwards from the bead cores 11 and the folded-over section 132 of the carcass layer 13 in the tire radial direction, in order to form the rim mating surface of the bead section, as described above. Furthermore, the rubber hardness of the rim pad rubber 17 is in the range of 50 or more to 80 or less. Additionally, the elongation at break of the rim pad rubber 17 is in the range of 150% or more to 450% or less.

[0035] The outer reinforcement rubber 19 is arranged in a sandwich-like manner between the folded-over section 132 of the carcass layer 13 and the wheel rim padding rubber 17 (see Fig. 2) In such a configuration, especially in the configuration in which, as described above, the bead filler is omitted, the spring properties of the bead section are enhanced by the outer reinforcing rubber 19, steering stability on dry road surfaces is ensured and the durability of the bead section is improved.

[0036] Furthermore, the rubber hardness of the outer reinforcement rubber 19 is preferably in the range of 65 or more to 105 or less, and more preferably in the range of 70 or more to 100 or less. This ensures the above-described effect of the outer reinforcement rubber 19 in a suitable manner.

[0037] Furthermore, the rubber hardness of the outer reinforcement rubber 19 is higher than the rubber hardness of the sidewall rubber 16 and the wheel rim pad rubber 17. More precisely, the difference ΔHs_SW between the rubber hardness of the sidewall rubber 16 and the rubber hardness of the outer reinforcement rubber 19 is preferably seven or more, and even more preferably twelve or more. Additionally, the difference ΔHs_RC between the rubber hardness of the wheel rim pad rubber 17 and the rubber hardness of the outer reinforcement rubber 19 is preferably three or more, and even more preferably seven or more. Consequently, the reinforcing effect on the spring properties of the bead section caused by the outer reinforcement rubber 19 is appropriately demonstrated. It should be noted that the lower limit of the rubber hardness difference ΔHs_SW is subject to limitations imposed by the lower limit of the rubber hardness of the outer reinforcement rubbers 19 described above.

[0038] Furthermore, the elongation at break of the outer reinforcement rubber 19 is preferably in the range of 50% or more to 400% or less, and more preferably in the range of 70% or more to 350% or less.

[0039] For example, in the configuration in Fig. 2. The rim pad rubber 17 extends over the entire area from a bead tip Bt to a bead base Bb to form the rim mating surface for a bead sheet 101 of a rim 10. The rim pad rubber 17 further extends outwards in the tire radial direction from the bead base Bb along the folded section 132 of the carcass layer 13 to form a mating surface with a flange 102 of the rim 10. Additionally, an end section is inserted outwards in the tire radial direction from the rim pad rubber 17 between the carcass layer 13 and the sidewall rubber 16 and extends outwards in the tire radial direction relative to the end section of the folded section 132 of the carcass layer 13 and the flange 102 of the rim 10. Furthermore, the bead section may include a bead protection strip (not illustrated).

[0040] It should be noted that the rim pad rubber 17 preferably extends to at least one area from a bead heel Bh to a central section (a center point Cm, described below) of an innermost layer in the tire radial direction from the bead cores 11. Therefore, the durability of the rim mating section of the bead section is appropriately ensured.

[0041] Furthermore, the outer reinforcement rubber 19 is included in the configuration in Fig. The outer reinforcement rubber 19 extends 2 in the tire radial direction and lies between the folded-over section 132 of the carcass layer 13 and the rim pad rubber 17. Furthermore, the end section of the outer reinforcement rubber 19 overlaps the bead core 11 in the tire radial direction. The outer reinforcement rubber 19 also extends outwards in the tire radial direction with respect to the end section of the folded-over section 132 of the carcass layer 13 and is sandwiched between the body section 131 of the carcass layer 13 and the sidewall rubber 16. Additionally, the outer reinforcement rubber 19 covers the end of the folded-over section 132 of the carcass layer 13 from the outside in the tire transverse direction.Furthermore, the outer side reinforcement rubber 19 is adjacent to the folded section 132 of the carcass layer 13 over the entire contact area between the body section 131 and the folded section 132 of the carcass layer 13. Therefore, the spring properties of the bead section are properly enhanced by the outer side reinforcement rubber 19, steering stability on dry road surfaces is improved, and the durability of the bead section is enhanced. Additionally, the rubber hardness of the outer side reinforcement rubber 19 is higher than that of the sidewall rubber 16 and the rim pad rubber 17. Accordingly, the rubber hardness distribution at or near the end of the folded section 132 of the carcass layer 13 decreases from the end of the carcass layer 13 towards the surface of the tire sidewall section.Accordingly, stress generated at or near the end section of the carcass layer 13 is reduced, and separation of a carcass end section is suppressed.

[0042] Furthermore, a radial height H3 from a measuring point of the tire inner diameter RD to an end section outside the outer reinforcement rubber 19 in the tire radial direction and a tire cross-sectional height SH (see Fig. 1) preferably a ratio of 0.10 ≤ H3 / SH ≤ 0.60, and more preferably a ratio of 0.15 ≤ H3 / SH ≤ 0.50. The radial height H3 of the outer reinforcing rubber 19 is accordingly manufactured. That is, the lower limit appropriately enhances the spring properties of the bead section with the outer reinforcing rubber 19, improves steering stability on dry road surfaces, and improves the durability of the bead section. Furthermore, the upper limit prevents an increase in tire weight due to an excessive amount of the outer reinforcing rubber 19.

[0043] The inner tire diameter RD is equal to the rim diameter of a given rim.

[0044] The radial height H3 is measured when the tire is mounted on a specified rim, inflated to a specified internal pressure, and in an unloaded state. More precisely, the radial height H3 is calculated as the difference between the diameter of the end section outside the outer reinforcing rubber 19 in the tire's radial direction and the tire's inner diameter RD.

[0045] The cross-sectional height SH is a distance equal to half the difference between the tire's outer diameter and the rim diameter and is measured when the tire is mounted on a specified rim, inflated to a specified internal pressure, and in an unloaded state.

[0046] "Specified rim" refers to an "applicable rim" as defined by the Japan Automobile Tyre Manufacturers Association Inc. (JATMA), a "design rim" as defined by the Tire and Rim Association, Inc. (TRA), or a "measuring rim" as defined by the European Tyre and Rim Technical Organisation (ETRTO). "Specified inflation pressure" refers to a "maximum air pressure" as defined by JATMA, the maximum value in "tire load limits at various cold inflation pressures" as defined by the TRA, and "inflation pressures" as defined by the ETRTO.Furthermore, "specified load" refers to a "maximum load capacity" as defined by JATMA, the maximum value in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or "LOAD CAPACITY" as defined by ETRTO. However, in the case of JATMA, the specified internal pressure for a passenger car tire is 180 kPa, and the specified load is 88% of the maximum load capacity.

[0047] A radial height H4 from the end section of the folded section 132 of the carcass layer 13 to the outer end section of the outer reinforcement rubber 19 in the tire radial direction preferably fulfills a ratio of 0.10 ≤ H4 / H2 to the radial height H2 of the contact section between the body section 131 and the folded section 132 of the carcass layer 13, and more preferably fulfills a ratio of 0.30 ≤ H4 / H2. Therefore, steering stability on dry road surfaces and the durability of the bead section are improved. It should be noted that the upper limit of the ratio H4 / H2 is subject to limitations imposed by the upper limit of the ratio H3 / H2 described above.

[0048] Additionally, the overlap H5 between the outer reinforcement rubber 19 and the bead core 11 in the tire radial direction preferably has a ratio of 0.05 ≤ H5 / H1 ≤ 1.00 to the radial height H1 of the bead cores 11, and more preferably a ratio of 0.10 ≤ H5 / H1 ≤ 1.00. Furthermore, the overlap H5 is preferably in the range of 5.0 mm ≤ H5. Accordingly, the overlap H5 between the outer reinforcement rubber 19 and the bead core 11 is manufactured accordingly. In particular, the lower limit ensures the overlap H5 and prevents separation of the rubber at the inner end section of the outer reinforcement rubber 19 in the tire radial direction.

[0049] The amount of overlap H5 is measured when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state.

[0050] It should be noted that, without being limited thereto, the outer reinforcement rubber 19 may be arranged outwards in the tire radial direction with respect to the bead cores 11 (not shown).

[0051] Additionally, the length T1 of a vertical line drawn from the end section of the folded section 132 of the carcass layer 13 to the outer surface of the tire sidewall section, and the thickness T2 of the outer sidewall reinforcing rubber 19 on the vertical line preferably satisfy a ratio of 0.10 ≤ T2 / T1 ≤ 0.90, and more preferably a ratio of 0.20 ≤ T2 / T1 ≤ 0.80. Therefore, the thickness T2 of the outer sidewall reinforcing rubber 19 is suitably manufactured. That is, the lower limit appropriately enhances the spring properties of the bead section with the outer sidewall reinforcing rubber 19, improves steering stability on dry road surfaces, and enhances the durability of the bead section. Furthermore, the upper limit prevents an increase in tire weight due to an excessive amount of the outer sidewall reinforcing rubber 19.

[0052] Additionally, in the configuration where the outer side reinforcing rubber 19 is provided instead of the bead filler as described above, a value K, defined by the following equation (1), is preferably 0.17 ≤ K, and more preferably 0.20 ≤ K. Therefore, the function of the outer side reinforcing rubber 19 is appropriately ensured. In equation (1), W is a tire inner width (mm), I is a tire inner diameter (inch), and B is a total cross-sectional area of ​​bead wires in bead cores (mm²). 2 ). K=W43×I23100×B2 Rate of change of rim pass section

[0053] In the configuration where bead fillers, as described above, have been omitted, the stiffness of the bead sections is reduced, and the rim contact pressure of the bead sections tends to decrease. For this reason, in the configuration of Fig. 2 the bead core 11 the following configuration to ensure the rim fit of the tire.

[0054] Fig. Figure 3 is an enlarged view showing the rim pass section of the Fig. 2 illustrated bulge section. Fig. 4 is an explanatory diagram showing the wire arrangement structure of the in Fig. 3 illustrated bead cores. Fig. Figure 5 is an explanatory diagram illustrating the rim fit section of the bead section in a state where the tire is mounted on the rim. These drawings illustrate Fig. 3 the rim profile section in its state before mounting on the rim, and Fig. Figure 5 illustrates the rim fitting section in a state after mounting on the rim. Fig. Figure 4 illustrates a cross-sectional view of the unvulcanized bead cores 11 in the radial direction when the components are separate.

[0055] In Fig. 2 The rim mating surface of the bead section includes the bead base Bb, the bead tip Bt, and the bead heel Bh and has a contour shape that is uniform in the tire circumferential direction. The bead base Bb is a flat area formed inward by the bead section in the tire radial direction and forms a contact surface with the bead sheet 101 of the rim. The bead tip Bt is a tip of the bead section with an L-shape or a V-shape in the cross-sectional view in the tire meridional direction and is located furthest inward on the rim mating surface in the tire transverse direction. The bead heel Bh is a curved section that connects the wall surface of the tire sidewall section to the bead base Bb.

[0056] The condition before the tire is mounted on the rim (see Fig. 2 and Fig. 3) is defined as a state where the positions of the right and left bead sections are set such that they correspond to measuring points of a rim width and rim diameter of the given rim in a state where the tire rotation axis is horizontal and the tire is upright on its own. This tire shape most closely resembles the tire shape in a tire vulcanization mold, that is, a natural tire shape before inflation.

[0057] The condition after the tire has been mounted on the rim (see Fig. 5) is defined as the state when the tire is mounted on the specified rim, inflated to the specified internal pressure, and unloaded. In the state where the tire is mounted on a rim, the rim mating surfaces of the bead sections fit into the rim 10 of the wheel, thus holding the tire. At this point, the bead base Bb of the rim mating surface is pressed against the bead sheet 101 of the rim 10 and brought into surface contact. This seals the mating section between the bead section and the rim 10, ensuring airtightness within the tire. Additionally, the bead heel Bh is positioned at the junction between the bead sheet 101 and the flange 102, an area outside the bead heel Bh of the rim mating surface rests against the flange 102 of the rim 10, and the bead section is held outwards in the transverse direction of the tire.

[0058] As in Fig. As shown in Figure 4, the bead cores 11 in the cross-sectional view in the tire meridian direction exhibit the predetermined wire arrangement structure in which the wire cross-sections of the bead wires 111 are arranged. The wire arrangement structure is described later.

[0059] In the cross-sectional view in the tire meridian direction, this is the state before the tire is mounted on the rim (see Fig. 3) A tangent line L1 is defined, which comes into contact with the innermost layer in the tire radial direction and the wire arrangement structures at the innermost and outermost points in the tire transverse direction within the wire arrangement structure of the bead cores 11 from the rim mating surface. The contact points C1 and C2 on the tangent line L1 to the corresponding wire cross-sections and the center point Cm of the contact points C1, C2 are defined. The thicknesses G1, G2, Gm in the tire radial direction from the contact points C1, C2 and the center point Cm on the rim mating surface are defined. More precisely, in the cross-sectional view in the tire meridian direction, the intersection points P1, P2 and Pm between straight lines passing through the contact points C1, C2, and the center point Cm and perpendicular to the tire axial direction and the bead base Bb are each drawn upwards.Distances between the contact points C1, C2 and the center point Cm and the intersection points P1, P2 and Pm are measured as the thicknesses G1, G2, Gm.

[0060] Similarly, the thicknesses G1', G2' and Gm' of the rim pass section are shown in the state after the tire has been mounted on the rim (see Fig. 5), defined.

[0061] At this stage, the rates of change ΔG1, ΔG2, ΔGm of the thicknesses G1, G2, Gm of the rim fitting section in the states before and after mounting on the rim are preferably in the range of 10% or more to 60% or less, more preferably in the range of 15% or more to 50% or less, even more preferably in the range of 20% or more to 45% or less, and most preferably in the range of 25% or more to 40% or less. Thus, the rates of change ΔG1, ΔG2, ΔGm of the thicknesses G1, G2, Gm are set higher than those of a typical tire structure including bead filler. Consequently, the rates of change ΔG1, ΔG2, ΔGm of change of the rim fitting section are manufactured accordingly. This means that the lower limit ensures the correct rim pressure and the correct tire fit on the rim. Furthermore, the upper limit prevents excessive rim pressure from impairing the tire's ease of mounting on the rim.

[0062] Using the thicknesses Gi and Gi', which are positioned on the rim at predetermined measuring points before and after mounting, a rate of change ΔGi is defined as ΔGi = (Gi - Gi') / Gi × 100. For example, the thickness ΔG1 is determined using the thickness G1 (see Fig. 3) before mounting on the rim and the thickness G1' (see Fig. 5) calculated after mounting on the rim as ΔG1 = (G1 - G1') / G1 × 100.

[0063] The change rates ΔG1, ΔG2, ΔGm of the rim pass section described above are, for example, achieved by a configuration of a wheel rim pad layer 20 described later (see Fig. 6) and a configuration of a cone angle of the bead base Bb (see Fig. 7) received.

[0064] Additionally, the rates of change ΔG1, ΔG2, ΔGm of the rim pass section preferably satisfy the condition |ΔGm - ΔG2| < |ΔG1 - ΔGm. Consequently, a difference in the rate of change |ΔG1 - ΔGm| at the bead tip Bt is set to a greater difference in the rate of change |ΔGm - ΔG2| at the bead heel Bh. More precisely, the rates of change ΔG1, ΔG2, ΔGm preferably satisfy the condition 20% ≤ |(ΔG1 - ΔGm) / (ΔGm - ΔG2)| ≤ 450%, and more preferably, they satisfy the condition 30% ≤ |(ΔG1 - ΔGm) / (ΔGm - ΔG2)| ≤ 300%. Therefore, the relationship between the rates of change ΔG1, ΔG2, ΔGm of the rim fit section is appropriately established. This means that the lower limit improves the rim fit of the tire. The upper limit also improves the ease of mounting the tire on the rim.

[0065] Furthermore, the rates of change ΔG1, ΔG2, ΔGm of the thicknesses G1, G2, Gm of the rim fit section preferably exhibit a ratio ΔG2 < ΔGm < ΔG1. In other words, the rates of change ΔG1, ΔG2, ΔGm increase towards the bead point Bt. Therefore, the rim fit of the tire is improved.

[0066] Additionally, the thicknesses G1, G2, Gm of the rim pass section of the tire, in the state before the tire is mounted on the rim, meet the requirements in Fig. Figure 3 illustrates a ratio of G2 < Gm < G1. In other words, the thicknesses G1, G2, and Gm of the rim connection section increase towards the bead core Bt. Therefore, the mutual relationship between the rates of change ΔG1, ΔG2, and ΔGm is suitably determined. Additionally, for a passenger car tire, the thickness G1 is preferably in the range G1 ≤ 8.0 mm, and more preferably in the range G1 ≤ 6.0 mm. The thickness G2 is also preferably in the range 1.0 mm ≤ G2, and more preferably in the range 1.5 mm ≤ G2. Therefore, the rubber volume in the rim connection section is suitably determined radially from the bead cores 11 inwards.

[0067] Furthermore, a width WC2 (mm) (see Fig. 4) the innermost layer of the wire arrangement structure of the bead cores 11, the rate of change ΔGm (%) at the center point Cm and the tire inner diameter RD (inches) (see Fig. 2) preferably a ratio of 1.0% mm / inch ≤ Wc2 × ΔGm / RD ≤ 50% mm / inch, more preferably a ratio of 2.0% mm / inch ≤ Wc2 × ΔGm / RD ≤ 40% mm / inch, and more preferably a ratio of 5.0% mm / inch ≤ Wc2 × ΔGm / RD ≤ 30% mm / inch. Therefore, the ratio between the width Wc2 of the innermost layer of the bead cores 11 and the rate of change ΔGm is suitably determined. That is, the lower limit ensures the rim fit of the tire. The upper limit also improves the ease of mounting the tire on the rim.

[0068] As in Fig. As illustrated in Figure 4, the width Wc2 of the innermost layer of the wire arrangement structure is measured as the maximum width including the innermost and outermost wire cross-sections in the tire transverse direction.

[0069] Additionally, the width Wc2 of the innermost layer in the wire arrangement structure is preferably in the range of 3.0 mm ≤ Wc2 ≤ 10.0 mm, and more preferably in the range of 4.5 mm ≤ Wc2 ≤ 9.6 mm. Wire arrangement structure of the bead cores

[0070] As in Fig. As illustrated in Figure 4, the bead cores 11 are formed by ring-shaped, multi-layered winding of the bead wires 111 and exhibit the predetermined wire arrangement configuration in the cross-sectional view in the tire meridional direction. The wire arrangement structure is determined by the arrangement of the wire cross-sections of the bead wires 111. Furthermore, the wire arrangement structure is formed by a multitude of layers stacked in the tire radial direction. These layers are formed from the multitude of wire cross-sections in a row in the tire transverse direction. Additionally, the innermost layer of the wire arrangement structure is essentially parallel to the rim mating surface of the bead section and lies opposite the bead sheet 101 of the rim 10 when the tire is fitted to the rim (see Figure 4). Fig. 3).

[0071] In one manufacturing process for the bead cores 11, a core forming template (not illustrated) is used, and one or more bead wires 111 are wound around the core forming template in a predetermined wire arrangement structure to form the unvulcanized bead cores 11. The formed bead cores 11 are then prevulcanized prior to a vulcanization forming step of a raw tire. Note that no such restriction is provided, and the prevulcanization of the bead cores 11 can be omitted. The unvulcanized bead cores 11 can be inserted into the raw tire, and the raw tire vulcanization forming step can be performed.

[0072] Additionally, the bead wire 111 is formed from a wire strand and an insulating rubber covering the wire strand (not illustrated). The wire strand is made of steel. The insulating rubber preferably consists of a rubber compound with a Mooney viscosity of 70 M or higher. The Mooney viscosity is calculated and determined according to JIS K6300-1:2013.

[0073] Furthermore, the configuration includes Fig. 2, as described above, the folded-over section 132 of the carcass layer 13 is in contact with the body section 131 of the carcass layer 13 to form the closed area X, which surrounds the bead cores 11. Additionally, the rubber layup ratio in the closed area X is set to be low, thereby reducing the weight of the bead section. Furthermore, to increase the durability of the bead section, a void section in the closed area X is preferably suppressed.

[0074] Thus, as in Fig. Figure 4 illustrates that the wire arrangement structure of the bead cores 11 has a wedge shape that projects outwards in the tire radial direction. More precisely, it is a layer in which the number of arrangements of the wire cross-sections in the wire arrangement structure is greatest (in the Fig. 4, the second layer from the innermost layer), is defined as the maximum arrangement layer. At this point, a number of layers of wire cross-sections extend outwards in the tire radial direction with respect to the maximum arrangement layer (three layers in Fig. 4) greater than the number of layers of wire cross-sections inwards in the tire radial direction with respect to the maximum arrangement layer (one layer in Fig. 4) Additionally, the number of wire cross-section arrangements in each layer decreases monotonically from the maximum arrangement layer outwards in the tire radial direction. Furthermore, the number of wire cross-section layers is preferably in the range of four or more to six or fewer. Additionally, the number of wire cross-section arrangements in the maximum arrangement layer of the wire arrangement structure is preferably four or five, and the number of wire cross-section arrangements in the outermost layer in the tire radial direction is preferably one or two.

[0075] The wire cross-sections are preferably arranged in a densest-packed structure in the outward region in the tire radial direction with respect to the maximum arrangement view. The term "densest-packed structure" refers to a condition in which the centers of the three adjacent wire cross-sections are arranged to form a substantially equilateral triangle in the cross-sectional view in the tire meridian direction. In such a densest-packed structure, the arrangement density of the wire cross-sections of the bead cores 11 is increased, and the core strength of the bead cores 11 is improved compared to a lattice arrangement structure in which rows of wire cross-sections are orthogonally arranged vertically and horizontally. It should be noted that in the densest-packed condition, it is not necessary for all groups of adjacent wire cross-sections to be in contact with each other, and some groups can be arranged with narrow gaps (not shown).

[0076] In such a configuration, as in Fig. As illustrated in Figure 3, the body section 131 and the folded-over section 132 of the carcass layer 13 extend outwards in the tire radial direction along the wedge shape of the wire arrangement structure, while bearing against the right and left side faces of the bead cores 11 in the tire transverse direction, and are joined in a Y-shape to come into contact with each other. Therefore, the gap between the connecting section of the body section 131 with the folded-over section 132 of the carcass layer 13 and the upper section (the so-called bead roof) of the bead core 11 outwards in the tire radial direction is reduced, and the durability of the bead section is improved. In particular, the structure described above, in which bead fillers are omitted, is therefore preferred because the rubber coverage ratio in the closed area X can be reduced.Additionally, the amount of the fold of the folded section 132 becomes small, and the durability of the bead section is improved, since the folded section 131 can be folded at an obtuse angle at the connection position with the body section 132.

[0077] The number of wire cross-section arrangements in the innermost layer in the tire radial direction in the wire arrangement structure is preferably three or four, and is preferably equal to or less than the number of wire cross-section arrangements in the maximum arrangement layer.

[0078] As in the Fig. As illustrated in Figure 4, the arrangement angles θ1, θ2 of the wire cross-sections at corner sections are defined inwards in the tire radial direction and inwards and outwards in the tire transverse direction within the wire arrangement structure. At this point, the arrangement angles θ1, θ2 are in the range of 80 degrees ≤ θ1 and 80 degrees ≤ θ2. That is, the arrangement angles θ1, θ2 of the wire cross-sections essentially form right angles or obtuse angles. Furthermore, as shown in Fig. Figure 4 illustrates that the arrangement angles θ1, θ2 of the wire cross-sections are preferably in the range of 100 degrees ≤ θ1 ≤ 150 degrees and 100 degrees ≤ θ2 ≤ 150 degrees. This suppresses interruption of the wire arrangement structure during tire vulcanization, improves the tire's rim fit, and enhances the durability of the bead section. Furthermore, if the arrangement angles θ1, θ2 of the wire cross-sections are obtuse, the carcass ply can be folded inwards along the corner sections from the bead cores 11 in the tire radial direction. Accordingly, the rubber layup ratio in the closed area X can be reduced, and the weight of the bead section can be further reduced.

[0079] The arrangement angles θ1, θ2 are measured as angles formed by lines connecting the centers of the three wire cross-sections, thus forming the corner sections of the wire arrangement structure.

[0080] Furthermore, fulfill in Fig. 4. The bead cores 11 have a maximum width Wc1 and a maximum height Hc1, and the total cross-sectional area S of the bead wires 111 of the bead cores 11 preferably has a ratio of 1.20 ≤ Wc1 × Hc1 / S ≤ 5.00, more preferably a ratio of 1.50 ≤ Wc1 × Hc1 / S ≤ 4.50, and even more preferably a ratio of 1.80 ≤ Wc1 × Hc1 / S ≤ 4.00. Therefore, the wire arrangement structure of the bead cores 11 is suitably manufactured. That is, the lower limit ensures the number of arrangements of wire cross-sections and ensures the rim fit of the tire. Furthermore, the upper limit reduces the weight of the bead cores 11.

[0081] It should be noted that the total cross-sectional area S of the bead wires does not include the cross-sectional area of ​​the insulating rubbers.

[0082] Furthermore, the total cross-sectional area S of the bead wires 111 is preferably in the range of 5 mm² 2≤ S ≤ 35 mm 2 , preferably in the range of 6 mm 2 ≤ S ≤ 32 mm 2 and even more so in the 7 mm range 2 ≤ S ≤ 28 mm 2 Therefore, the total cross-sectional area S of the bead wires 111 is appropriately manufactured. In particular, the lower limit ensures the total cross-sectional area S of the bead wires 111 and guarantees the rim fit of the tire. Furthermore, the upper limit reduces the weight of the bead cores 11.

[0083] Furthermore, there is an outer diameter Φ (see Fig. 4) of the bead wire 111 preferably in the range of 0.8 mm ≤ Φ ≤ 1.5 mm, and more preferably in the range of 0.9 mm ≤ Φ ≤ 1.4 mm, and even more preferably in the range of 1.0 mm ≤ Φ ≤ 1.3 mm. Thus, the outer diameter Φ of the bead wire 111 is suitably produced. That is, the lower limit ensures the outer diameter Φ of the bead wire 111 and ensures the rim fit of the tire. In addition, the upper limit reduces the weight of the bead cores 11.

[0084] Furthermore, fulfill in Fig. 4. The height Hc2 from the tangent line L1 of the innermost layer in the wire arrangement structure to the maximum width position of the bead cores 11, and the maximum height Hc1 of the bead cores 11 preferably a ratio of 1.10 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.80, and more preferably a ratio of 1.30 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.50, and even more preferably a ratio of 1.50 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.30. Therefore, the wire arrangement structure of the bead cores 11 is suitably manufactured.

[0085] The maximum height Hc1 of the bead cores is measured as the maximum height of the bead cores from the tangent line L1.

[0086] The height Hc2 of the widest position of the bead cores is measured as the distance between the tangent line L1 and an imaginary line connecting the centers of the wire cross-sections that form the maximum layup layer. In a configuration where the wire layup structure includes multiple maximum layup layers, the outermost maximum layup layer in the tire radial direction is used to measure the height Hc2 of the maximum width position.

[0087] For example, in the configuration in Fig. 4. The number of wire cross-section layers is five, and the number of wire cross-section arrangements is set to 3-4-3-2-1 in the order of the innermost layer in the tire radial direction. Thus, the number of wire cross-section arrangements in the maximum arrangement layer is four. Additionally, the number of wire cross-section layers outward in the tire radial direction with respect to the maximum arrangement layer is three, and the number of wire cross-section layers inward in the tire radial direction with respect to the maximum arrangement layer is one. The maximum arrangement layer is therefore asymmetrical in the tire radial direction and arranged such that it occupies the inward position in the tire radial direction with respect to the center position in the tire radial direction of the wire arrangement structure.The wire arrangement structure has a configuration that extends outwards from the maximum arrangement layer in the tire radial direction. Furthermore, the number of wire cross-sections in each layer decreases successively from the maximum arrangement layer outwards in the tire radial direction. All wire cross-sections are arranged in the densest-packed structure. Both arrangement angles θ1, θ2 of the wire cross-sections at the left and right corner sections in the tire radial direction of the wire arrangement structure are approximately 135 degrees (particularly in the range of 130 degrees to 140 degrees). Moreover, the maximum arrangement layer of wire cross-sections is not the innermost layer in the tire radial direction. Additionally, the number of wire cross-sections in each layer increases successively from the innermost layer to the maximum arrangement layer. This optimizes the wire arrangement structure.

[0088] Furthermore, it fulfills in Fig. 3. A distance Hg in the tire radial direction from the end section of the bead cores 11 outwards in the tire radial direction to the contact section between the body section 131 and the folded-over section 132 of the carcass layer 13 preferably has a ratio of Hg / Φ ≤ 7.0 to the outer diameter Φ of the bead wire 111 and more preferably a ratio of Hg / Φ ≤ 3.0. Therefore, the stiffness around the bead cores 11 is improved. It should be noted that the lower limit of the ratio Hg / Φ 0 ≤ Hg / Φ is at Hg = 0. Thickness of the rim pass section

[0089] Fig. 6 is an explanatory diagram that illustrates the Fig. 3 illustrated rim fitting section. The same drawing illustrates the rim fitting section in its state before mounting on the rim. In the same drawing are components that are the same as those in Fig. The three illustrated components are labelled with the same reference symbols, and their explanations are omitted.

[0090] In Fig. 6. As described above, the thickness G2 in the tire radial direction is defined from the contact point C2 between the tangent line L1 of the innermost layer of the wire arrangement structure and the wire cross-section at the outermost point in the tire transverse direction up to the rim mating surface. At this point, the thickness G2 and the outer diameter Φ satisfy (see Fig. 4) The bead wire 111 preferably has a ratio of 1.3 ≤ G2 / Φ ≤ 9.5 and more preferably a ratio of 1.8 ≤ G2 / Φ ≤ 5.5. Therefore, the thickness G2 of the rim fitting section is manufactured accordingly. In particular, the lower limit ensures the thickness G2 of the rim fitting section and guarantees the rim fit of the tire. Furthermore, the upper limit prevents a deterioration in the machinability of mounting the tire on the rim due to excessive thickness G2 of the rim fitting pressure.

[0091] Furthermore, in Fig. 6. An intersection point Q is defined between a straight line passing through the contact point C2 of the bead core 11 and parallel to the tire's transverse direction, and an outer wall surface of the rim fitting section in the tire's transverse direction. A thickness W in the tire's transverse direction from contact point C2 of the bead core 11 to point Q on the rim fitting surface is also defined. At this point, the thickness Wh and the outer diameter Φ satisfy (see Fig. 4) The bead wire 111 preferably has a ratio of 2.0 ≤ Wh / Φ ≤ 15.0, and more preferably a ratio of 2.5 ≤ Wh / Φ ≤ 10.0. Therefore, the thickness Wh of the rim fitting section is manufactured accordingly. That is, the lower limit ensures the thickness Wh of the rim fitting section, guarantees the rim fit of the tire, and ensures the durability of the rim fitting section. Furthermore, the upper limit prevents a deterioration in the machinability of mounting the tire on the rim due to excessive thickness Wh of the rim fitting pressure.

[0092] Additionally, as in Fig. As shown in Figure 6, the cushioning rubber layer 20 is inserted between the innermost layer of the bead cores 11 and the rim cushioning rubber 17. The rim cushioning layer 20 is an element with a rubber hardness lower than that of the rim cushioning rubber 17. For example, it includes the inner liner 18 and a connecting rubber (not illustrated) linking the inner liner 18 and the carcass layer 101, but does not include the carcass layer. Additionally, the rim cushioning layer 20 can have an integral structure with the inner liner 18 and the connecting rubber, or it can have a separate structure (not illustrated). Furthermore, the rim cushioning layer 20 can be made of the same rubber material as the inner liner 18 and the connecting rubber, or it can be made of different rubber materials (not illustrated).The cushioning rubber layer 20 extends over a region from contact point C1 to the center point Cm of the bead cores 11 in the transverse direction of the tire, and preferably over a region from contact point C1 to contact point C2. In such a configuration, the cushioning rubber layer 20 is inserted between the innermost layer of the bead cores 11 and the rim mating surface of the bead section. This increases the rates of change ΔG1, ΔG2, ΔGm of the rim mating section, thereby improving the rim fit of the tire. Furthermore, the contact pressure of the rim mating surface on the rim 10 is made uniform.

[0093] Furthermore, the rubber hardness of the cushioning rubber layer 20 is lower than the rubber hardness of the wheel rim cushioning rubber 17, preferably by five or more, and more preferably by eight or more. Therefore, the effect of increasing the rates of change ΔG1, ΔG2, ΔGm of the rim profile section is appropriately preserved.

[0094] For example, in the configuration in Fig. 6 In the cross-sectional view, the cushioning rubber layer 20 extends outwards from the tire cavity surface in the tire transverse direction along the folded-over section 132 of the carcass layer 13 and is inserted between the bead cores 11 and the rim cushioning rubber 17. Furthermore, the cushioning rubber layer 20 extends beyond the center point Cm of the innermost layer of the bead cores 11 to the outermost contact point C2. The end section of the cushioning rubber layer 20 terminates inwards in the tire radial direction with respect to the tangent line L1 of the bead cores 11. Accordingly, the end section of the cushioning rubber layer 20 does not extend outwards in the tire transverse direction from the bead core 11 to the side surface.Therefore, the rates of change ΔG1, ΔG2 and ΔGm between the bead cores 11 and the rim mating surface (especially the bead base Bb) are effectively increased, while the stiffness between the bead cores 11 and the flange 102 (see . Fig. 2) the rim 10 is ensured in a suitable manner. However, no such restriction is provided, and the end section from the cushioning rubber layer 20 outwards in the tire transverse direction can extend outwards in the tire radial direction with respect to the tangent line L1 of the bead cores 11.

[0095] In Fig. 6. Furthermore, the thicknesses Tc1, Tc2 of the cushioning rubber layer 20 between measuring points C1, P1; and C2 and P2 of the thicknesses G1, G2 of the rim fitting section preferably satisfy the ratio Tc2 < Tc1. In other words, the thickness Tc1 of the cushioning rubber layer 20 on the bead toe side Bt is preferably thicker than the thickness Tc2 of the cushioning rubber layer 20 on the bead heel side Bh. Thus, the rate of change ΔG1 of the rim fitting section on the bead toe side Bt is greater than the rate of change ΔG2 of the rim fitting section on the bead heel side Bh (ΔG2 < ΔG1), and the rim fit of the tire is improved.

[0096] Furthermore, as described above, adjusting the ratio of the thickness of the cushioning rubber layer 20 between the measuring points C1 and P1; C2 and P2; and Cm and Pm of the thicknesses of G1, G2, Gm of the rim fitting section allows the adjustment of the ratio between the rates of change ΔG1, ΔG2, ΔGm of the rim fitting section.

[0097] Furthermore, the average thickness of the cushioning rubber layer 20 in the area from contact point C1 to contact point C2 in the tire's transverse direction is preferably in the range of 0.3 mm or more to 3.0 mm or less. Therefore, the average thickness of the cushioning rubber layer 20 is suitably determined. In other words, the lower limit appropriately ensures that the cushioning rubber layer 20 increases the rates of change ΔG1, ΔG2, ΔGm of the rim mating section. Moreover, the upper limit prevents a decrease in the stiffness of the rim mating section due to an excessive amount of cushioning rubber layer 20.

[0098] Furthermore, fulfill in Fig. 6. The thickness G1 of the rim mating section on the side of the bead Bt and the thickness Tc1 of the cushioning rubber layer 20 preferably have a ratio of 0.03 ≤ Tc1 / G1 ≤ 0.95, and more preferably a ratio of 0.05 ≤ Tc1 / G1 ≤ 0.85. Therefore, the average thickness of the cushioning rubber layer 20 is suitably manufactured. That is, the lower limit ensures the proper functioning of the cushioning rubber layer 20 and increases the rate of change ΔG1 of the rim mating section. Furthermore, the upper limit ensures the thickness G1 of the rim cushioning rubber 17 and suitably secures the rim fit of the tire.

[0099] Additionally, on the side of the tire cavity, the cushioning rubber layer 20 extends outwards in the tire radial direction from the measuring point of height H1 (see Fig. 2) the bead cores 11 outwards in the tire radial direction, preferably by 5 mm or more. Shape of the rim mating surface

[0100] Fig. 7 is an explanatory diagram that illustrates the Fig. 3 illustrated rim fitting section. The same drawing illustrates the rim fitting section in its state before mounting on the rim. In the same drawing are components that are the same as those in Fig. The three illustrated components are labelled with the same reference symbols, and their explanations are omitted.

[0101] As in Fig. Figure 7 illustrates a tangent line of the rim pass surface in the cross-sectional view in the tire meridian direction in the state before mounting on the rim at an intersection point P2 defined as an extension line L2 of the bead base Bb.

[0102] At this time, the angle of inclination α of the extension line L2 of the bead base Bb with respect to the tangent line L1 of the bead cores 11 is preferably in the range of 3 degrees ≤ α ≤ 15 degrees and more preferably in the range of 6 degrees ≤ α ≤ 12 degrees.

[0103] Furthermore, the inclination angle α (degrees) of the extension line L2 of the bead base Bb, the rate of change ΔGm (%) of the rim fit section, and a nominal tire width WA (dimensionless) preferably satisfy a ratio of 0%·degrees ≤ ΔGm × α / WA ≤ 7%·degrees, and more preferably a ratio of 0.5%·degrees ≤ ΔGm × α / WA ≤ 5.0%·degrees. Therefore, a ratio of ΔGm × α / WA, which indicates the rim fit of the tire, is appropriately established. In other words, generally, as the nominal tire width WA increases, the rim fit of the tire tends to be lower. Furthermore, the larger the inclination angle α of the bead base Bb and the rate of change ΔGm of the rim fit section, the greater the contact pressure against the rim, thus improving the tire's rim fit. Accordingly, the lower limit increases the ratio ΔGm × α / WA and improves the tire's rim fit.Furthermore, the upper limit prevents a deterioration in the machinability of mounting the tire on the rim due to excessive rim pressure. Note that if the inclination angle α = 0 degrees, then ΔGm × α / WA = 0 is satisfied.

[0104] As in Fig. Figure 7 illustrates that, in the cross-sectional view in the tire meridian direction, when the bead base Bb has a shape formed by connecting the two types of linear sections with different angles of inclination (so-called two-stage conical shape), the extension line L2 of the linear section on the side of the bead heel Bh and an extension line L3 of the linear section on the side of the bead toe Bt of the rim mating surface are also defined.

[0105] At this point, the inclination angles α, β of the extension lines L2 and L3 of the bead base Bb with respect to the tangent line L1 of the bead cores 11 preferably satisfy a ratio of 0 ≤ β / α ≤ 5.0, and more preferably a ratio of 1.8 ≤ β / α ≤ 4.0. Therefore, the two-stage conical shape of the bead base Bb is suitably produced. In other words, the lower limit appropriately achieves the effect of improving the rim fit of the tire through the two-stage conical shape. Furthermore, the upper limit suppresses the occurrence of a vulcanization defect in the bead base Bb.

[0106] Furthermore, in Fig. 7 defines the intersection point R of the two types of linear sections of the bulge base Bb.

[0107] At this point, the distance Lr in the tire transverse direction from the bead point Bt to the intersection point R and the distance Lm in the tire transverse direction from the bead point Bt to the center point Cm preferably fulfill a ratio of 0.50 ≤ Lr / Lm ≤ 4.0, and more preferably they fulfill a ratio of 0.70 ≤ Lr / Lm ≤ 3.3. Therefore, the position of the intersection point R is suitably manufactured, whereby the effect of improving the rim fit of the tire due to the two-stage conical shape is appropriately achieved.

[0108] Furthermore, the configuration includes Fig. 7 of the arrangement angles θ1 (see Fig. 4) The wire cross-sections at the corner section are angled inwards in the tire radial direction and inwards in the tire transverse direction of the wire arrangement structure of the bead cores 11 in the range of 130 degrees or more to 140 degrees or less. Furthermore, the two types of linear sections of the bead base Bb are connected by a smooth arc that projects outwards in the tire radial direction. Additionally, the intersection point R is positioned between the contact point C1 and the center point Cm of the bead cores 11.

[0109] In Fig. In section 7, a distance Dt in the tire radial direction from the contact point C1 of the bead cores 11 to the bead tip Bt and a distance Wt in the tire transverse direction are defined. At this point, the distances Dt, Wt, and the thickness G1 in the tire radial direction from the contact point C1 to the rim mating surface preferably satisfy a ratio of 7 degrees ≤ arctan {(Dt - G1) / Wt} ≤ 30 degrees, and more preferably satisfy the ratio 9 degrees ≤ arctan {(Dt - G1) / Wt} ≤ 25 degrees. Therefore, a gradient of the rim mating surface with respect to the tire axial direction from the bead cores 11 to the bead tip Bt is suitably produced. That is, the lower limit ensures the gradient of the rim mating surface and ensures the rim fit of the tire. Furthermore, the upper limit prevents a reduction in the machinability of mounting the tire on the rim due to the excessive gradient of the rim mating surface.

[0110] The distances Dt from contact point C1 to bead heel Bt and the distance Wt are measured in the state before the tire is mounted on the rim. Modified examples

[0111] Fig. 8, Fig. 9, Fig. 10, Fig. 11 to Fig. 12 are explanatory diagrams that show modified examples of the in Fig. The four illustrated bead cores are shown. These drawings illustrate a cross-sectional view of the unvulcanized bead cores 11 in the radial direction when the components are separate.

[0112] In the configuration in Fig. 4. The tangent line L1 to the innermost layer of the bead cores 11 runs parallel to the tire's transverse direction. Therefore, the angle of inclination X of the tangent line L1 with respect to the tire's transverse direction X = 0 degrees.

[0113] However, no such restriction is intended, and as in Fig. As illustrated in Figure 8, the bead cores 11 are inclined with respect to the tire's transverse direction. In particular, the bead cores 11 can be inclined inwards in the tire's radial direction on the side of the bead section Bt (see Figure 8). Fig. 3) be inclined. In such a configuration, the tangent line L1 of the innermost layer of the bead cores 11 of the bead base Bb approaches the rim mating surface parallel to it. At this point, the inclination angle X of the tangent line L1 with respect to the tire transverse direction is preferably in the range of -10 degrees ≤ X ≤ 30 degrees. It should be noted that the range of the relative inclination angle α of the extension line L2 of the bead base Bb with respect to the tangent line L1 of the bead cores 11 is as described above.

[0114] Additionally, the configuration in Fig. 4. As described above, the number of wire cross-section arrangements in sequence from the innermost layer in the tire radial direction is set to 3-4-3-2-1. Therefore, the number of wire cross-section layers is five, and the number of wire cross-section arrangements in the outermost layer in the tire radial direction is one.

[0115] In contrast, the configuration in Fig. 9. The number of layers of wire cross-sections is four, and the number of wire cross-section arrangements is set to 3-4-3-2 in the order of the innermost layer in the tire radial direction. In the Fig. In the configuration illustrated in Figure 10, the number of wire cross-section layers is six, and the number of wire cross-section arrangements is set to 3-4-5-4-3-2 in the order of the innermost layer in the tire radial direction. Therefore, the number of wire cross-section layers can be four or six. Furthermore, the number of wire cross-section arrangements in the outermost layer in the tire radial direction can be two. In such cases, the number of wire cross-section layers extending outwards in the tire radial direction is greater than the maximum arrangement layer (two layers in Figure 10). Fig. 9 and three layers in Fig. 10) greater than the number of layers of wire cross-sections inwards in the tire radial direction with respect to the maximum arrangement layer (one layer in Fig. 9 and two layers in Fig. 10). Furthermore, the number of wire cross-section arrangements in each layer decreases successively from the maximum arrangement layer outwards in the tire radial direction.

[0116] Furthermore, the configuration in Fig. 4. The number of wire cross-section arrangements in the innermost layer in the tire radial direction is less than the number of wire cross-section arrangements in the maximum arrangement layer (the second layer of the innermost layer). Furthermore, all wire cross-sections forming the wire arrangement structure are arranged in the most densely packed structure. Both arrangement angles θ1, θ2 of the wire cross-sections are located at the corner sections facing inwards in the tire radial direction and inwards and outwards in the tire transverse direction within the wire arrangement structure, in the range of 130 degrees or more to 140 degrees or less.

[0117] In contrast, the configuration in Fig. 11 and Fig. 12. The number of layers of wire cross-sections is five, and the number of wire cross-section arrangements is set to 4-4-3-2-1 in the order from the innermost layer in the tire radial direction. Thus, the number of wire cross-section arrangements in the innermost layer is the same as the number of wire cross-section arrangements in the maximum arrangement layer. In the configuration in Fig. 11. The arrangement angle θ1 of the wire cross-sections at the corner section, both inwards in the tire radial direction and inwards in the tire transverse direction of the wire arrangement structure, is an acute angle and lies in the range of 55 degrees or more to 65 degrees or less. On the other hand, the arrangement angle θ2 of the wire cross-section at the corner section, extending outwards in the tire transverse direction, is an obtuse angle and lies in the range of 130 degrees or more to 140 degrees or less. In the Fig. In the configuration illustrated in Figure 12, both arrangement angles θ1, θ2 of the wire cross-sections at the left and right corner sections in the tire radial direction of the wire arrangement structure are substantially right angles and are in the range of 85 degrees or more to 95 degrees or less. In this way, at least the arrangement angle θ2 of the wire cross-sections at the corner section facing outwards in the tire transverse direction is preferably a substantially right angle or an obtuse angle. In the configuration illustrated in Fig. In the illustrated configuration 12, the wire cross-sections are arranged in a grid pattern from the maximum packing layers inwards in the tire radial direction. In this way, it is sufficient that the wire cross-sections in the densest packed structure are arranged at least in each layer from the maximum packing layer outwards in the tire radial direction. Tire sidewall thickness

[0118] Fig. 13 is an enlarged view showing the tire sidewall section of the Fig. Figure 1 illustrates a pneumatic tire. The same drawing illustrates an enlarged cross-sectional view in the tire's meridional direction at maximum tire width position A.

[0119] In Fig. 13. The total thickness K1 of the tire sidewall section at the maximum width position A is preferably in the range of 2.5 mm ≤ K1 ≤ 6.5 mm, and more preferably in the range of 3.0 mm ≤ K1 ≤ 6.0 mm. The total thickness K1 of the tire sidewall section is therefore manufactured accordingly. That is, the lower limit ensures the total thickness K1 of the tire sidewall section and also ensures tire rolling resistance. The upper limit further ensures weight reduction of the tire.

[0120] The total thickness K1 of the tire sidewall section is measured as the distance between the inner surface of the tire and the outer surface of the tire at the maximum tire width position A in the cross-sectional view in the tire meridional direction.

[0121] Furthermore, the thickness K2 of a sidewall rubber 16 at the maximum width position A is preferably in the range of 0.3 mm ≤ K2 ≤ 3.0 mm, and more preferably in the range of 0.5 mm ≤ K2 ≤ 2.5 mm. The thickness K2 of the sidewall rubber 16 is therefore manufactured accordingly. That is, the lower limit ensures the thickness K2 of the sidewall rubber 16 and provides cut resistance to the tire sidewall section. The upper limit further ensures weight reduction of the tire. Effects

[0122] As described above, the pneumatic tire 1 includes the bead cores 11, the carcass layer 13, and the rim rubber 17. The bead cores 11 are formed by ring-shaped and multi-layered winding of one or more bead wires 111. The carcass layer 13 is formed from the carcass ply, which consists of a single layer or multiple layers. The carcass layer 13 is folded over to wrap around and extend between the bead cores 11. The rim rubber 17 is arranged along the folded-over section 132 of the carcass layer 13 to form a rim-fitting surface of the bead section (see Fig. 1 and Fig. 2) The folded-over section 132 of the carcass layer 13 comes into contact with the body section 131 of the carcass layer 13 in the cross-sectional view in the tire meridian direction to form the closed area X that surrounds the bead cores 11 (see Fig. 2) The rubber coverage ratio in the closed area X is 15% or less. The bead cores 11 have the predetermined wire arrangement structure formed by arranging wire cross-sections of the bead wires 111 in the cross-sectional view in the tire meridional direction (see Fig. 4) The tangent line L1, the contact points C1 and C2, the midpoint Cm of the contact points C1 and C2, and the thickness Gm are defined. The tangent line L1 contacts the innermost layer in the tire radial direction and the innermost and outermost wire cross-sections in the tire transverse direction within the wire arrangement structure from the rim mating surface. The contact points C1 and C2 of the tangent line L1 are located on the innermost and outermost wire cross-sections. The thickness Gm extends in the tire transverse direction from the midpoint Cm to the rim mating surface (see Fig. 3) At this point, the rate of change ΔGm of the thickness Gm between the state before and after mounting on the rim is in the range of 10% or more to 60% or less.

[0123] In such a configuration (1), the rubber coverage ratio in the closed area X surrounded by the body section 131 and the folded-over section 132 of the carcass layer 13, i.e., the rubber volume around the bead cores 11, is set significantly low. Since bead fillers can thus be omitted, the weight of the tire can be reduced.

[0124] Furthermore (2) the advantage lies in the fact that the rate of change ΔGm of the rim fit section of the bead section is appropriately manufactured. That is, the lower limit ensures the rim fit pressure and ensures the rim fit of the tire. Above all, the effect is particularly advantageous in the structure in which no bead filler is omitted (see Fig. 2) Furthermore, the upper limit prevents a deterioration in the ease of mounting the tire onto the rim due to excessive rim pressure.

[0125] If, in pneumatic tire 1, the layer in which the number of arrangements of the wire cross-sectional sections is the maximum in the wire arrangement structure is defined as the maximum arrangement layer (in Fig. 4 (the second layer from the innermost layer), is the number of layers of wire cross-sections outwards in the tire radial direction with respect to the maximum arrangement layer (three layers in Fig. 4) greater than the number of layers of wire cross-section sections inwards in the tire radial direction with respect to the maximum arrangement layer (one layer in Fig. 4) Additionally, the number of wire cross-section arrangements in each layer decreases monotonically outward in the tire radial direction relative to the maximum arrangement layer. This configuration offers the advantage of reducing the gap between the connecting section of the body section 131 with the folded-over section 132 of the carcass layer 13 and the upper section (the so-called bead roof) of the bead core 11 outward in the tire radial direction, thus improving the durability of the bead section. In particular, the structure described above, in which bead fillers are omitted, is therefore preferred because the rubber coverage ratio in the closed area X can be reduced.Additionally, there is the advantage that the amount of the fold of the folded section 132 becomes small, and the durability of the bead section is improved, since the folded section 131 can fold at an obtuse angle at the connection position with the body section 132.

[0126] Furthermore, the width WC2 in pneumatic tire 1 (see Fig. 4) of the innermost layer of the bead cores 11, the rate of change ΔGm at the center Cm (see Fig. 3) and the tire inner diameter RD (see Fig. 2) a ratio of 1.0% ·mm / inch ≤ Wc2 × ΔGm / RD ≤ 50% ·mm / inch. Therefore, an advantage lies in the fact that the ratio between the width Wc2 of the innermost layer of the bead cores 11 and the rate of change ΔGm is appropriately established. That is, the lower limit ensures the rim fit of the tire. The upper limit also improves the ease of mounting the tire on the rim.

[0127] If the extension line L2 (see Fig. 7) The linear section of the bead base BB of the rim mating surface is further defined in the pneumatic tire 1 in the cross-sectional view in the tire meridian direction. The inclination angle α of the extension line L2 with respect to the tangent line L1, the rate of change ΔGm, and the nominal tire width WA satisfy a ratio of 0%·degree ≤ ΔGm × α / WA ≤ 7%·degree. This has the advantage that the ratio ΔGm × α / WA, which indicates the rim fit of the tire, is appropriately determined. That is, the lower limit increases the ratio ΔGm × α / WA and improves the rim fit of the tire. In addition, the upper limit prevents a deterioration in the machinability of mounting the tire on the rim due to excessive rim pressure.

[0128] Furthermore, in the pneumatic tire 1, in the cross-sectional view in the tire meridian direction, the bead base Bp of the rim mating surface is formed by connecting the two types of linear sections with different angles of inclination (see Fig. 7) Furthermore, the extension line L2 of the linear section on the bead heel side Bh and the extension line L3 of the linear section on the bead toe side Bt of the bead base Bb of the rim mating surface are defined. At this point, the angles of inclination α, β of the extension lines L2 and L3 with respect to the tangent line L1 have a ratio of 0 ≤ β / α ≤ 5.0. This has the advantage that the two-stage conical shape of the bead base Bb is appropriately produced. In other words, the lower limit appropriately achieves the effect of improving the rim fit of the tire through the two-stage conical shape. Moreover, the upper limit suppresses the occurrence of a vulcanization defect in the bead base Bb.

[0129] Furthermore, in pneumatic tire 1, the intersection point R of the two types of linear sections of the bead base Bb is defined (see Fig. 7) At this point, a distance Lr in the tire transverse direction from the bead point Bt to the intersection point R and a distance Lm in the tire transverse direction from the bead point Bt to the center point Cm satisfy a ratio of 0.50 ≤ Lr / Lm ≤ 4.0. This is advantageous because the position of the intersection point R is suitably produced, thereby achieving the desired effect of improving the rim fit of the tire due to the two-stage conical shape.

[0130] Furthermore, in the pneumatic tire 1, the arrangement angle θ1 of the wire cross-section at the corner section lies inwards in the tire radial direction and inwards in the tire transverse direction of the wire arrangement in a range of 80 degrees ≤ θ1 (see Fig. 4) Furthermore, in the cross-sectional view in the tire meridian direction, the bead base Bp of the rim mating surface is formed by connecting the two types of linear sections with different angles of inclination (see Fig. 7) If the intersection point R of the two types of linear sections of the bead base is further defined, the intersection point R is positioned between the contact point C1 and the center point Cm in the tire's transverse direction. This has the advantage that the position of the intersection point R of the two-stage conical shape is appropriately manufactured and the rim fit of the tire is improved.

[0131] Furthermore, the pneumatic tire 1 encloses the cushioning rubber layer (rim rubber 17 in Fig. 2) one which has a lower rubber hardness than that of the wheel rim padding rubber 17 and which is inserted between the innermost layer of the bead cores 11 and the wheel rim padding rubber 17 (see Fig. 2) The configuration is advantageous because the layer of cushioning rubber inserted between the bead cores 11 and the rim fitting surface increases the rates of change ΔG1, ΔG2 and ΔGm of the rim fitting section and improves the rim fit of the tire.

[0132] Furthermore, the padding rubber layer (rim padding rubber 17 in) extends Fig. 2) in the pneumatic tire 1 along the area from the contact point C1 to the center point Cm of the bead cores 11 in the tire transverse direction (see Fig. 3) This is advantageous because the effect of improving the rim fit, which is achieved by the cushioning rubber layer, is effectively maintained.

[0133] In addition, the pneumatic tire 1 further includes the outer side reinforcement rubber 19, which is arranged between the folded-over section 132 of the carcass layer 13 and the rim pad rubber 17 (see Fig. 2) The configuration, in particular the configuration in which, as described above, bead filler is omitted, is advantageous because the spring properties of the bead section are enhanced by the outer reinforcing rubber 19 and steering stability on dry road surfaces is ensured.

[0134] Furthermore, the radial height H3 (see Fig. 2) from the measuring point of the tire inner diameter RD to the end section of the outer reinforcement rubber 19 outwards in the tire radial direction and the tire cross-sectional height SH (see Fig. 1) The ratio of 0.10 ≤ H3 / SH ≤ 0.60 in the pneumatic tire 1. This has the advantage that the radial height H3 of the outer reinforcing rubber 19 is appropriately manufactured. That is, the lower limit appropriately enhances the spring properties of the bead section with the outer reinforcing rubber 19 and improves steering stability on dry road surfaces. In addition, the upper limit suppresses the increase in tire weight due to an excessive amount of the outer reinforcing rubber 19.

[0135] Furthermore, the length T1 of the vertical line drawn from the end section of the folded section 132 of the carcass layer 13 to the outer surface of the tire sidewall section, and the thickness T2 of the outer sidewall reinforcement rubber 19 on the vertical line, satisfy the ratio of 0.10 ≤ T2 / T1 ≤ 0.90 in the pneumatic tire 1. This has the advantage that the thickness T2 of the outer sidewall reinforcement rubber 19 is appropriately manufactured. That is, the lower limit appropriately enhances the spring properties of the bead section with the outer sidewall reinforcement rubber 19 and improves steering stability on dry road surfaces. In addition, the upper limit suppresses the increase in tire weight due to an excessive amount of the outer sidewall reinforcement rubber 19.

[0136] Furthermore, in the pneumatic tire 1, the arrangement angle θ2 of the wire cross-section at the corner section lies inwards in the tire radial direction and outwards in the tire transverse direction of the wire arrangement structure in the range of 80 degrees ≤ θ2 (see Fig. 4) This has the advantage of suppressing any disruption of the wire arrangement structure during tire vulcanization and improving the rim fit of the tire.

[0137] Furthermore, in the pneumatic tire 1, the height Hc2 from the tangent line L1 to the maximum width position of the bead cores 11 and the maximum height Hc1 of the bead cores 11 have the ratio of 1.10 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.80 (see Fig. 4) This has the advantage that the wire arrangement structure of the bead cores 11 is suitably produced.

[0138] In the pneumatic tire 1, the actual length La2 of the contact section between the body section 131 and the folded section 132 of the carcass layer 13 furthermore fulfills the ratio 0.30 ≤ La2 / La1 ≤ 2.00 with respect to the circumferential length La1 of the closed area X. Therefore, the actual length La2 of the self-contacting section of the carcass layer 13 is manufactured accordingly. In other words, this has the advantage that the lower limit appropriately ensures the spring properties of the carcass layer 13 and guarantees steering stability on dry road surfaces. Moreover, the upper limit suppresses an increase in tire weight due to the excessive length of the folded section 132. Example

[0139] Fig. Figure 14 is a table showing results of performance tests of pneumatic tires according to the embodiment of the invention. Fig. Figure 15 is an explanatory diagram illustrating the bead cores of a test tire of a state-of-the-art example.

[0140] In the performance test, a variety of test tires with a tire size of 205 / 55R16 were evaluated with regard to (1) tire mass, (2) rim fit and (3) steering stability. (1) The tire mass is calculated as the mean mass of five test tires with the same structure. The measurement results are expressed as index values ​​and evaluated using the prior art as a reference value (100). The smaller the values ​​in this evaluation, the lighter the test tires, which is preferred. Additionally, it can be said that if the index is 99 or less, the weight of the tire is reduced compared to that of existing tire structures, including bead fillers. (2) In the evaluation of rim fit, the test tires are mounted on rims with a rim size of 16 × 6.5 J, and the test tires are inflated to an air pressure of 230 kPa and a load specified by JATMA is applied. The test tires are mounted on an off-road vehicle (SUV) with a 2000 cc engine as the test vehicle. The test vehicle then performs a J-turn on a predetermined route while the air pressures of the test tires are gradually reduced, and the air pressure at the time of air leakage is measured. The measurement results are expressed as index values ​​and evaluated by determining the prior art as the reference value (100). In this evaluation, higher values ​​are to be preferred. (3) In the assessment of steering stability, the test vehicle is driven at speeds of 60 km / h to 100 km / h on a test course with dry road surfaces and a flat surface. The test driver then performs a sensory evaluation of steering during lane changes and cornering, as well as stability while driving forward. The results of the evaluation are expressed as index values ​​and assessed using the state of the art as a reference value (100). Higher values ​​are preferred in this evaluation.

[0141] The test tires in examples 1 to 19 achieve the weight reduction of the tires by having structures with omitted bead fillers (see Fig. 1 and Fig. 2) Additionally, the thicknesses G1, Gm, and G2 of the rim section, in the state prior to mounting on the rim, exhibit a ratio of G2 < Gm < G1. Furthermore, the rubber hardness of the rim pad rubber 17 is 70. The outer side reinforcement rubber 19 is also made of the same material as the rim pad rubber 17 and is integrated into the rim pad rubber 17. The tire cross-sectional height SH is 112 mm, and the length T1 of the vertical line drawn from the end section of the folded-over section 132 of the carcass layer 13 of the outer surface of the tire sidewall section is 7.0 mm.

[0142] In the test tire of the prior art example, the bead cores 1 in the structure of the test tire of Example 11 have the wire arrangement structure that is described in Fig. Figure 15 illustrates this. The test tires in comparison examples 1 and 2 are described in the... Fig. 1 and Fig.2 illustrated configurations of the insulating rubber of the bead cores 11 are increased and the rubber covering ratio in the closed area X is increased.

[0143] As can be seen from the test results, the test tires of examples 1 to 19 can improve the rim fit and the steering stability of the tire, while reducing the weight of the tires.

[0144] A pneumatic tire (1) is revealed, comprising: Bead cores (11) formed by ring-shaped and multi-layered winding of one or a plurality of bead wires (111); a carcass layer (13) formed from a carcass layer of a single layer or a plurality of layers, wherein the carcass layer (13) is folded over to wrap around the bead cores (11) and extends between the bead cores (11); a wheel rim pad rubber (17) arranged along a folded-over section (132) of the carcass layer (13) to form a rim mating surface of a bead section; wherein the folded-over section (132) of the carcass layer (13) contacts a body section (131) of the carcass layer (13) in a cross-sectional view in a tire meridian direction to form a closed area (X) surrounding the bead cores (11); a rubber covering ratio in the closed area (X) is in a range of 15% or less, wherein the rubber covering ratio in the cross-sectional view in the tire meridional direction is the ratio the cross-sectional area of ​​the rubber material in the closed area (X) is calculated as a percentage of the total cross-sectional area of ​​the closed area (X); the bead cores (11) have a predetermined wire arrangement structure formed by arranging wire cross-sections of the bead wires (111) in the cross-sectional view in the tire meridian direction; a tangent line L1, contact points C1, C2, a midpoint Cm of the contact points C1, C2 and a thickness Gm are defined, wherein the tangent line L1 contacts an innermost wire layer in a tire radial direction and the wire cross-sections are located at the innermost and outermost points in a tire transverse direction in the wire arrangement structure from the rim mating surface side, wherein the contact points C1, C2 of the tangent line L1 are located at the innermost and outermost points on the wire cross-sections, and wherein the thickness Gm extends in the tire radial direction from the midpoint Cm to the rim mating surface; and a rate of change ΔGm of thickness Gm between a state before and after mounting on a rim in a range of 10% or more to 60% or less. List of reference symbols 1 pneumatic tire 11 bead core 111 Tire bead wire 13 Carcass layer 131 Body section 132 Turned section 14 Belt layer 141, 142 Cross belt 143 Belt cover 144 Belt edge cover 15 tread rubber 16 side wall rubber 17 Wheel rim pad rubber 18 Inner Soul 19 Outer reinforcement rubber 10 rim 101 Bead leaf 102 Flange

Claims

Pneumatic tire (1) comprising: bead cores (11) formed by annular and multi-layer winding of one or a plurality of bead wires (111); a carcass layer (13) formed from a carcass ply of a single layer or a plurality of layers, wherein the carcass layer (13) is folded over to wrap around the bead cores (11) and extends between the bead cores (11); a rim pad rubber (17) arranged along a folded-over section (132) of the carcass layer (13) to form a rim mating surface of a bead section; wherein the folded-over section (132) of the carcass layer (13) contacts a body section (131) of the carcass layer (13) in a cross-sectional view in a tire meridian direction to form a closed area (X) surrounding the bead cores (11);a rubber covering ratio in the closed area (X) is in a range of 15% or less, wherein the rubber covering ratio in the cross-sectional view in the tire meridional direction is calculated as the ratio of the cross-sectional area of ​​the rubber material in the closed area (X) to the total cross-sectional area of ​​the closed area (X); the bead cores (11) have a predetermined wire arrangement structure formed by arranging wire cross-sections of the bead wires (111) in the cross-sectional view in the tire meridional direction;a tangent line L1, contact points C1, C2, a midpoint Cm of the contact points C1, C2 and a thickness Gm are defined, wherein the tangent line L1 contacts an innermost wire layer in a tire radial direction and the wire cross-sections at the innermost and outermost points in a tire transverse direction in the wire arrangement structure from the rim mating surface side, wherein the contact points C1, C2 of the tangent line L1 are on the wire cross-sections at the innermost and outermost points, and wherein the thickness Gm extends in the tire radial direction from the midpoint Cm to the rim mating surface; a rate of change ΔGm of the thickness Gm between a state before and after mounting on a rim is in a range of 10% or more to 60% or less;In the cross-sectional view in the tire meridian direction, a bead base (Bb) of the rim mating surface is formed by connecting two types of linear sections with different angles of inclination, an extension line L2 of the linear section on a bead heel side and an extension line L3 of the linear section on a bead toe side of the bead base (Bb) of the rim mating surface are defined, and the angles of inclination α, β of the extension lines L2 and L3 with respect to the tangent line L1 satisfy a ratio of 0 ≤ β / α ≤ 5.

0. Pneumatic tire (1) according to claim 1, wherein a layer in which a number of arrangements of the wire cross-sections is a maximum in the wire arrangement structure is defined as a maximum arrangement layer, a number of layers of the wire cross-sections outwards in the tire radial direction with respect to the maximum arrangement layer is greater than a number of layers of the wire cross-sections inwards in the tire radial direction with respect to the maximum arrangement layer, and a number of arrangements of the wire cross-sections in each layer outwards in the tire radial direction with respect to the maximum arrangement layer decreases monotonically from the maximum arrangement layer. Pneumatic tire (1) according to claim 1 or 2, wherein a width Wc2 (mm) of the innermost layer of the bead cores (11), the rate of change ΔGm (%) at the center point Cm and a tire inner diameter RD (inch) satisfy a ratio of 1.0 % ·mm / inch ≤ Wc2 × ΔGm / RD ≤ 50 %·mm / inch. according to one of claims 1 to 3, wherein in the cross-sectional view in the tire meridian direction an extension line L2 of a linear section of a bead base (Bb) of the rim mating surface is defined, and an inclination angle α (degrees) of the extension line L2 with respect to the tangent line L1, the rate of change ΔGm (%) and a tire nominal width WA (dimensionless) satisfy a ratio of 0 %·degrees ≤ ΔGm × α / WA ≤ 7 %·degrees. Pneumatic tire (1) according to one of claims 1 to 4, wherein in the cross-sectional view in the tire meridional direction a bead base (Bb) of the rim mating surface is formed by connecting two types of linear sections with different angles of inclination, an intersection point R of the two types of linear sections of the bead base is defined, and a distance Lr in the tire transverse direction from a bead tip (Bt) to the intersection point R and a distance Lm in the tire transverse direction from the to the center point Cm satisfy a ratio of 0.50 ≤ Lr / Lm ≤ 4.

0. Pneumatic tire (1) according to one of claims 1 to 5, wherein an arrangement angle θ1 of the wire cross sections at a corner section is inward in the tire radial direction and inward in the tire transverse direction of the wire arrangement in a range of 80 degrees ≤ θ1, in the cross-sectional view in the tire meridian direction a bead base (Bb) of the rim mating surface is formed by connecting two types of linear sections with different angles of inclination, an intersection point R of the two types of linear sections of the bead base (Bb) is defined, and the intersection point R is positioned between the contact point C1 and the center point Cm in the tire transverse direction. Pneumatic tire (1) according to one of claims 1 to 6, comprising a cushioning rubber layer having a rubber hardness that is less than the rubber hardness of the rim cushioning rubber (17), wherein the cushioning rubber layer is inserted between the innermost wire layer of the bead cores (11) in the radial direction of the tire and the rim cushioning rubber (17). Pneumatic tire (1) according to claim 7, wherein the cushioning rubber layer extends over an area from the contact point C1 to the center point Cm of the bead cores (11) in the transverse direction of the tire. Pneumatic tire (1) according to one of claims 1 to 8, comprising an outer side reinforcement rubber (19) having a rubber hardness higher than the rubber hardness of the rim pad rubber (17), wherein the outer side reinforcement rubber (19) is arranged between the folded-over section (132) of the carcass layer (13) and the rim pad rubber (17). Pneumatic tire (1) according to claim 9, wherein a radial height H3 from a measuring point of the tire inner diameter RD to an end section extending outwards from the outer reinforcement rubber (19) in the tire radial direction and a tire cross-sectional height SH satisfy a ratio of 0.10 ≤ H3 / SH ≤ 0.

60. Pneumatic tire (1) according to claim 9 or 10, wherein a length T1 of a vertical line drawn from an end section of the folded-over section (132) of the carcass layer (13) to an outer surface of a tire side section, and a thickness T2 of the outer surface reinforcement rubber (19) on the vertical line satisfy a ratio of 0.10 ≤ T2 / T1 ≤ 0.

90. Pneumatic tire (1) according to one of claims 1 to 11, wherein an arrangement angle θ2 of the wire cross sections at a corner section lies inwards in the tire radial direction and outwards in the tire transverse direction of the wire arrangement structure in a range of 80 degrees ≤ θ2. Pneumatic tire (1) according to one of claims 1 to 12, wherein a height Hc2 from the tangent line L1 to a maximum width position of the bead cores (11) and a maximum height Hc1 of the bead cores (11) satisfy a ratio of 1.10 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.

80. Pneumatic tire (1) according to one of claims 1 to 13, wherein an actual length La2 of a contact section between the body section (131) and the folded-over section (132) of the carcass layer (13) satisfies a ratio of 0.30 ≤ La2 / La1 ≤ 2.00 with respect to a circumferential length La1 of the closed area.

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