pneumatic tires

Abstract

Pneumatic tires (1), comprising: Bead cores (11) formed by ring-shaped and multi-layered winding of one or more tire bead wires (111); a carcass layer (13) formed from a carcass layer consisting 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 to extend 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 part (131) of the carcass layer (13) in a cross-sectional view in the tire meridian direction to form a closed area (X) surrounding the bead cores (11); a rubber covering ratio in the closed area (X) which is in a range of 15% or less, wherein the rubber covering ratio is a percentage of a 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 meridional direction; wherein the bead cores (11) have a predetermined wire arrangement structure formed by arranging wire cross sections of the tire bead wires (111) in the cross-sectional view in the tire meridian direction; wherein in the cross-sectional view external tangents to the tire bead wires (111) at outer circumferential surfaces of the bead cores (11) form a polygon that surrounds the wire arrangement structure, wherein a circumferential length of the polygon is a circumferential length L of the wire arrangement structure; wherein a self-contact height CH of the carcass layer is a maximum height of a contact section between the body part (131) and the folded-over section (132) of the carcass layer (13) in the tire radial direction; and the self-contact height CH of the carcass layer (13) and the circumferential length L of the wire arrangement structure, which have a ratio 1.0 ≤ CH / L ≤ 10.0.

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 bead sections. A prior art pneumatic tire addressing this topic is known as the technology described in Patent Document 1. In Patent Document 1, bead fillers are omitted to reduce the tire's weight. List of prior art patent documents

[0003] Patent Document 1: JP 2008-149778 A Brief description of the invention: Technical problem

[0004] However, with the pneumatic tire described above, according to the current state of the art, a deterioration in the rim fit of the tire can occur due to the omission 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 reducing the weight of the tire. Solution to the problem

[0006] To solve this problem, a pneumatic tire according to one embodiment of the invention includes bead cores, a carcass layer, and a rim pad. The bead cores are formed by ring-shaped, multi-layer winding of one or more tire bead wires. The carcass layer consists of a carcass ply made of a single layer or multiple layers. The carcass layer is folded over to wrap around the bead cores and extend between them. The rim pad 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 portion of the carcass layer in a cross-sectional view along a tire meridional direction to form a closed area surrounding the bead cores.The rubber cover ratio in the closed area is 15% or less. The bead cores have a predetermined wire arrangement structure, formed by arranging the cross-sections of the tire bead wires in the cross-sectional view along the tire's meridian. The self-contact height CH of the carcass layer and the circumferential length L of the wire arrangement structure have a ratio of 1.0 ≤ CH / L ≤ 10.0. Advantageous effects of the invention

[0007] In a pneumatic tire according to one embodiment of the invention, (1) the rubber layup ratio in the closed area surrounded by the body and the folded-over section of the carcass layer, i.e., a rubber volume around the bead cores, is set significantly low. This has the advantage that bead fillers are omitted and the tire weight is reduced. Furthermore, this has the advantage that (2) the CH / L ratio appropriately establishes the self-contact height CH of the carcass layer. That is, the lower limit ensures the stiffness of the bead section and guarantees the tire's rim fit. Moreover, the upper limit prevents an increase in tire weight due to an excessive amount of folded-over section. 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 the 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 that shows a modified example of the one 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. 14 is an enlarged view showing a shoulder section of the Fig. 1 illustrated pneumatic tire. Fig. Figure 15 is a table showing results of performance tests of pneumatic tires according to embodiments of the invention. Fig. Figure 16 is an explanatory diagram illustrating the bead cores of a test tire representing 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. In addition, the modified examples described in the embodiments can be combined as required 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 half a region in the tire radial direction. Likewise, the same drawing illustrates a radial tire for a passenger car as an example of a pneumatic tire.

[0010] 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 illustrated). 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 lateral 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.

[0011] A pneumatic tire 1 has a ring-shaped structure with the tire's axis of rotation as its center 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).

[0012] The pair of bead cores 11, 11 is formed by ring-shaped and multi-layered winding of one or more steel tire 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.

[0013] The carcass layer 13 has a single-layer structure, formed from a single carcass ply, or a multi-layer structure, formed from 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 of 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 and fixed to the bead cores 11. The carcass ply(s) of the carcass layer 13 are manufactured by a rolling process on multiple carcass cord threads coated with rubber, which are made of steel or an organic fiber material (e.g., aramid, nylon, polyester, and rayon).The carcass ply(s) has / have a carcass angle (defined as an inclination angle of a longitudinal direction of the carcass cord threads relative to the tire circumference direction) with an absolute value in the range of 80 degrees or more to 90 degrees or less, and preferably less than 90 degrees (specifically 89 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 plurality of carcass plies.

[0014] 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 is arranged 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 belt cord threads coated with rubber, which are made of steel or an organic fiber material. The cross belts 141, 142 have a belt angle with an absolute value in the range of 20 degrees or more to 55 degrees or less. It should be noted that the belt angles of the cross belts 141, 142 are not limited to the range described above and any angle can be set.Furthermore, the pair of cross belts 141, 142 exhibit belt angles (defined as the angle of inclination 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-layer 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 exhibit belt angles with an absolute value 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 more belt cover cord threads with a coating rubber and repeatedly wrapping the strip material spirally around the outer circumferential surfaces of the cross belts 141, 142 in the direction of the tire circumference. It should be noted that the belt cover 143 and the pair of belt edge covers 144 can be omitted (not illustrated).

[0015] The tread rubber 15 is arranged outwards in the tire radial direction from the carcass layer 13 and the belt layer 14 and forms a tread section of the tire. The pair of sidewall rubbers 16, 16 are arranged outwards in the tire transverse direction from the carcass layer 13 and form right and left sidewall sections. The pair of respective rim pad rubbers 17, 17 are arranged inwards in the tire radial direction from the right and left bead cores 11, 11 and the folded-over sections of the carcass layer 13 to form rim mating surfaces of the bead sections.

[0016] The inner liner 18 is an air penetration prevention layer located 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 a major 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

[0017] Fig. 2 is a cross-sectional view showing the bead section of the in Fig. Figure 1 illustrates an air-filled tire. The same drawing illustrates a cross-sectional view in the tire meridian direction of the bead section in a state before the tire is mounted on a rim.

[0018] 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 part 131. Likewise, the closed area X continues around the entire circumference of the tire, forming an annular, closed space surrounding the bead cores 11.

[0019] The closed area X is defined as an area surrounded in a cross-sectional view by the carcass layer of the carcass layer 13 in the tire meridional direction. More precisely, the area surrounded by the surface of the coating rubber of the carcass layer is defined as the closed area X.

[0020] 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 plurality of layered carcass plies (not illustrated), in which the closed region X can be formed by mutual contact of the different carcass layers. For example, the following configuration (not illustrated) is assumed. The carcass layer 13 has a two-layer structure formed by layers of first and second carcass plies; a folded-over section of the first carcass layer ends blindly in the middle of a radial height H1 (see Figure 1). Fig. 2) the bead cores 11 without contact with the body part 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 part of the first carcass layer.

[0021] 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 part 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. Thus, the objective of reducing the tire's weight 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. This ensures a suitable amount of insulating rubber for the bead cores 11.

[0022] The rubber coverage ratio is calculated as a percentage (%) 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.

[0023] 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 part 131. The carcass layer of the carcass layer 13 is also wound along the outer circumferential surfaces of the bead cores 11. Thus, only the component parts of the bead cores 11 are present in the closed area X. The component parts of the bead cores 11 include tire bead wires 111, the insulating rubbers, bead covers, and winding turns.

[0024] It should be noted that the bead filler is a reinforcing rubber designed to fill a triangular gap between the bead cores, the body section, and the folded-over portion of the carcass ply, and it is designed to increase the stiffness of the bead section. The bead filler generally has a triangular cross-section and a rubber hardness of 65 or more to 99 or less.

[0025] The rubber hardness is measured according to JIS K 6253. Self-contact height of the carcass layer

[0026] In the configuration described above, in which the bead filler is omitted, as in Fig. As illustrated in Figure 2, the folded-over section 132 of the carcass layer 13 is in surface contact with the body part 131 of the carcass layer 13 and is fixed. This increases the stiffness of the bead section and improves the durability of the bead section.

[0027] At this stage, the self-contact height CH of the carcass layer 13 and a circumferential length L (dimension symbol omitted in the drawing) of a wire arrangement structure of the bead cores 11 preferably have a ratio of 1.0 ≤ CH / L ≤ 10.0 and more preferably a ratio of 2.2 ≤ CH / L ≤ 7.0. Thus, the self-contact height CH of the carcass layer 13 is suitably achieved. In other words, the lower limit ensures that the folded section 132 stably contacts the body part 131, thereby ensuring the stiffness of the bead section and guaranteeing the rim fit of the tire and the durability of the bead section. Furthermore, the upper limit prevents an increase in tire weight due to an excessive amount of the folded section 132.However, since the amount of the increase in tire weight due to the increase in self-contact height CH is much smaller than the amount of the reduction in tire weight due to the above-described omission of bead fillers, the weight reduction of the tire is achieved in a suitable manner even in the above-described configuration.

[0028] The self-contact height CH of the carcass layer is measured as the maximum height of a contact section between the body part and the folded-over section of the carcass layer in the tire radial direction.

[0029] The circumferential length L of the bead cores is measured as follows. First, the wire arrangement structure of the bead cores is identified in the cross-sectional view in the tire meridional direction. In particular, the wire arrangement structure of the bead cores is identified as they are in their individual state before being attached to a raw tire (that is, before the bead cores lose their shape in a tire vulcanization molding process). Next, external tangents of the tire bead wires, which form the outer circumferential surfaces of the bead cores, are connected to form a polygon (see the diagram described later). Fig. 4), which surrounds the wire arrangement structure, is drawn. The perimeter length of the polygon is measured as the perimeter length L of the bead cores.

[0030] Furthermore, the circumferential length L of the wire arrangement structure of the bead cores 11 and a tire cross-sectional height SH preferably have a ratio of 0.12 ≤ L / SH ≤ 1.00 and more preferably a ratio of 0.14 ≤ L / SH ≤ 0.50. Thus, the circumferential length L of the bead cores 11 is suitably produced. In other words, if the tire cross-sectional height SH becomes large, the rim fit of the tire tends to deteriorate. That is, the lower limit ensures the circumferential length L of the bead cores 11 and thus the rim fit of the tire. Moreover, the upper limit prevents an increase in tire weight due to an excessive number of bead cores 11.

[0031] The tire 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.

[0032] "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 internal 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.

[0033] Furthermore, the tire cross-sectional height SH and the self-contact height CH of the carcass layer 13 preferably have a ratio of 2.4 mm ≤ SH - CH ≤ 120 mm and more preferably a ratio of 2.6 mm ≤ SH - CH ≤ 99 mm. Accordingly, a difference between the tire cross-sectional height SH and the self-contact height CH of the carcass layer 13 is suitably generated.

[0034] Furthermore, the self-contact height CH, the folded height PH of the carcass layer 13, and the tire aspect ratio HF preferably have a ratio of 0.60 × (HF / 100) ≤ CH / PH ≤ 0.98, more preferably a ratio of 0.70 × (HF / 100) ≤ CH / PH ≤ 0.96, and even more preferably a ratio of 0.80 × (HF / 100) ≤ CH / PH ≤ 0.95. Thus, the CH / PH ratio is suitably achieved. In other words, if the tire aspect ratio HF becomes large, the rim fit of the tire tends to deteriorate. Therefore, the lower limit ensures the ratio of the self-contact height CH to the folded height PH of the carcass layer 13 and thus guarantees the rim fit of the tire. Furthermore, the upper limit suppresses an increase in tire weight due to the excessive amount of the folded section 132.

[0035] The tire aspect ratio is calculated as a ratio (%) between the tire cross-sectional height and the tire cross-sectional width.

[0036] The cross-sectional height is measured as a linear distance between sidewalls (excluding, for example, patterns and alphanumeric characters on the tire sidewall surfaces) when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state.

[0037] The folded height PH of the carcass layer is measured as a distance in the tire radial direction from a measuring point of a rim diameter to a folded end section of the carcass layer when the tire is mounted on a specified rim, inflated to the specified internal pressure and in an unloaded state.

[0038] Furthermore, the actual length La2 (dimension symbol omitted in the drawing) of the contact section between the body part 131 and the folded section 132 of the carcass layer 13 preferably has a ratio of 1.0 ≤ La2 / La1 ≤ 8.0 to a circumferential length La1 (dimension symbol omitted in the drawing) of the closed area X, and more preferably has a ratio of 2.1 ≤ La2 / La1 ≤ 6.0. Thus, the actual length La2 of the self-contacting section of the carcass layer 13 is suitably produced. 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. Moreover, the upper limit prevents an increase in tire weight due to an excessive amount of the folded section 132.

[0039] 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 forms the boundary line of the closed area X.

[0040] The actual length La2 of the contact section is measured as a circumferential length of the self-contacting section between the body part and the folded-over section of the carcass layer in the cross-sectional view in the tire meridian direction.

[0041] For example, in the configuration of Fig. 1. The folded-over section 132 of the carcass layer 13 extends outwards in the tire radial direction beyond a maximum tire width position A. Furthermore, an end section (reference symbol omitted in the drawing) of the folded-over section 132 is held in place by being sandwiched between the body part 131 of the carcass layer 13 and the innermost layer of the belt layer 14 (the cross belt 141 on the inner diameter side of the tire). Fig. 1) is arranged. However, no such restriction is intended, and the folded section 132 of the carcass layer 13 can be positioned in the center of the tire sidewall section (not illustrated). In this case, the end section of the folded section 132 of the carcass layer 13 preferably contacts the body part 131 of the carcass layer 13. In such a configuration, a 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 from the body part 131 (not illustrated). Accordingly, the separation of the circumferential rubber starting from the end section of the folded section 132 is suppressed.

[0042] Furthermore, the configuration of Fig. 1, as in Fig. Figure 2 illustrates this, with the bead filler omitted and the rubber coverage ratio of the closed area X surrounding the bead cores 11 set to be significantly small. Thus, the folded section 132 of the carcass layer 13 near the bead cores 11 is in contact with the body part 131 of the carcass layer 13. Accordingly, the self-contact height CH of the carcass layer 13 is increased. Tire thickness above cores

[0043] Furthermore, fulfill in Fig. 2. A tire thickness Wo outwards in the transverse direction and a tire thickness Wi inwards in the transverse direction of the carcass layer 13 at radial positions that are twice the height H1 of the bead cores 11, preferably fulfilling a condition of 3.0 mm ≤ Wo + Wi ≤ 20 mm, more preferably a condition of 4.0 mm ≤ Wo + Wi ≤ 18 mm, and even more preferably a condition of 2.0 mm ≤ Wo + Wi ≤ 8 mm. Thus, the tire thicknesses inside and outside the carcass layer 13 in the region from the bead cores 11 outwards in the radial direction are suitably produced. That is, the stiffness of the region has a significant influence on the rim fit of the tire. Accordingly, the lower limit ensures the tire thicknesses in the region and guarantees the rim fit of the tire. Furthermore, the upper limit prevents an increase in tire weight due to excessive tire thickness.

[0044] 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 radial direction of the wire cross-section at the outermost point in the tire transverse direction to an outermost layer in the tire radial direction and an outer end in the tire radial direction of the wire cross-section at the outermost point in the tire transverse direction.

[0045] The tire thicknesses Wo, Wi are measured as the sum of the thicknesses in the transverse direction of the tire links at radial positions that are twice the radial height H1 of the bead cores. In addition to the rubber links, such as the sidewall rubber 16 and the rim pad rubber 17, the tire link includes a reinforcing link, such as a nylon reinforcing layer. Furthermore, component links (carcass cord threads and coating rubbers) of the carcass layer 13 are excluded from the tire thickness measurements.

[0046] Furthermore, fulfill in Fig. 2. The tire thickness Wo outwards in the transverse direction and the tire thickness Wi inwards in the transverse direction of the carcass layer 13 at radial positions that are twice the height H1 of the bead cores 11, preferably satisfy a condition 1.0 ≤ Wo / Wi ≤ 10.0, more preferably a condition 2.0 ≤ Wo / Wi ≤ 8.0, and even more preferably a condition 3.0 ≤ Wo / Wi ≤ 6.0. Thus, the tire thicknesses inside and outside the carcass layer 13 in the region from the bead cores 11 outwards in the radial direction are suitably produced. That is, the tire thicknesses in the region from the carcass layer 13 outwards in the transverse direction have a significant influence on the rim fit of the tire. Therefore, the lower limit ensures the tire thickness Wo from the carcass layer 13 outwards in the tire transverse direction and ensures the rim fit of the tire.Furthermore, the upper limit prevents an increase in tire weight due to excessive tire thickness. Outer reinforcement rubber

[0047] 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.

[0048] Each of the sidewall rubbers 16 is arranged transversely to the outside of the carcass layer 13 and forms the sidewall sections of the tire described above. Furthermore, the rubber hardness of the sidewall rubber 16 is in the range of 40 or more to 70 or less. Additionally, the elongation at break of the sidewall rubber 16 is in the range of 400% or more to 650% or less.

[0049] The elongation at break is measured according to the JIS K6251 standard.

[0050] The rim pad rubber 17 is arranged such that it faces 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.

[0051] 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.

[0052] 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.

[0053] 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. In particular, 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 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 more preferably seven or more. The reinforcing effect on the spring properties of the bead section caused by the outer reinforcement rubber 19 is shown accordingly. 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.

[0054] Furthermore, the elongation at break of the outer surface 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.

[0055] For example, in the configuration of 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 surface structure 101 of a rim 10. Furthermore, the rim pad rubber 17 extends outwards in the tire radial direction from the bead base Bb along the folded-over section 132 of the carcass layer 13 to form a mating surface for a flange 102 of the rim 10. Additionally, an end section of the rim pad rubber 17 is inserted outwards in the tire radial direction between the carcass layer 13 and the sidewall rubber 16 and 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 the flange 102 of the rim 10. Furthermore, the bead section may include a bead protection strip (not illustrated).

[0056] 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, which is described below) of an innermost layer in the tire radial direction of the bead cores 11. This ensures the durability of the rim mating section of the bead section in a suitable manner.

[0057] Furthermore, the outer reinforcement rubber 19 in the configuration of Fig. 2. The outer reinforcement rubber 19 has a long shape in the tire radial direction and is sandwiched 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 part 131 of the carcass layer 13 and the sidewall rubber 16. Finally, the outer reinforcement rubber 19 covers the end of the folded-over section 132 of the carcass layer 13 outwards 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. Thus, the spring properties of the bead section are appropriately 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. In addition, 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 section of the folded section 132 of the carcass layer 13 decreases from the end section 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 the circumferential rubber is suppressed.

[0058] Furthermore, a radial height H3 from a measuring point of the tire inner diameter RD to an end section of the outer reinforcement rubber 19 outwards in the tire radial direction and a tire cross-sectional height SH (see Fig. 1) preferably have a ratio of 0.10 ≤ H3 / SH ≤ 0.60 and more preferably a ratio of 0.15 ≤ H3 / SH ≤ 0.50. Accordingly, the radial height H3 of the outer reinforcing rubber 19 is manufactured appropriately. In other words, the lower limit appropriately enhances the spring properties of the bead section through the outer 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 reinforcing rubber 19.

[0059] The inner tire diameter RD is equal to the rim diameter of a given rim.

[0060] 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. Specifically, the radial height H3 is calculated as the difference between the diameter of the end section extending outwards from the outer reinforcement rubber 19 in the tire radial direction and the tire's inner diameter RD.

[0061] Furthermore, the thickness Wr of the outer sidewall reinforcement rubber 19 and the tire thickness Wo, extending from the carcass layer 13 outwards in the transverse direction of the tire, preferably have a ratio of 0.10 ≤ Wr / Wo ≤ 0.90 at radial positions that are twice the radial height H1 of the bead cores 11, and more preferably have a ratio of 0.20 ≤ Wr / Wo ≤ 0.80. Thus, the thickness Wr of the outer sidewall reinforcement rubber 19 is suitably produced. In other words, the lower limit appropriately enhances the spring properties of the bead section through the outer sidewall reinforcement rubber 19, improves steering stability on dry road surfaces, and enhances the durability of the bead section. Moreover, the upper limit prevents an increase in tire weight due to an excessive amount of the outer sidewall reinforcement rubber 19.

[0062] Furthermore, in the configuration where the outer side reinforcing rubber 19 is provided instead of the bead filler, as described above, a value K, determined by equation (1) below, is preferably 0.17 ≤ K and more preferably 0.20 ≤ K. The function of the outer side reinforcing rubber 19 is thus appropriately ensured. In equation (1), W denotes a nominal tire width (mm), I denotes a nominal tire inner diameter (inch), and B denotes a total cross-sectional area of ​​tire bead wires in bead cores (mm²). 2 ). K=W43×I23100×B2 Rate of change of the rim pass section

[0063] 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.

[0064] 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 the state before mounting it on the rim and Fig. Figure 5 illustrates the rim fitting section in a state after mounting it 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.

[0065] 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 from the bead section in the tire radial direction and forms a contact surface with the bead surface structure 101 of the rim 10. 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.

[0066] 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's axis of rotation is horizontally oriented and the tire is mounted 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.

[0067] The condition after the tire is 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 the rim, the rim mating surfaces of the bead sections fit against the rim 10 of the wheel, thus holding the tire in place. At this point, the bead base Bb of the rim mating surface is pressed against the bead surface structure 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. Furthermore, the bead heel Bh is located at a connecting section between the bead surface structure 101 and the flange 102, an area outside the bead heel Bh of the rim mating surface lies against the flange 102 of the rim 10 and the bead section is held outwards in the tire transverse direction.

[0068] As in Fig. As illustrated in Figure 4, the bead cores 11 in the cross-sectional view in the tire meridian direction exhibit the previously defined wire arrangement structure in which the wire cross-sections of the tire bead wires 111 are arranged. The wire arrangement structure is described later.

[0069] In the cross-sectional view in the tire meridian direction in the state before the tire is mounted on the rim (see Fig. 3) A tangent line L1, which contacts the innermost layer in the tire radial direction, and the wire cross-sections at the innermost and outermost points from the rim mating surface in the tire transverse direction are determined in the wire arrangement structure of the bead cores 11. The contact points C1 and C2 of the tangent line L1 to the corresponding wire cross-sections and the midpoint Cm of the contact points C1 and C2 are determined. Furthermore, the thicknesses G1, G2, and Gm in the tire radial direction from the contact points C1 and C2 and the midpoint Cm to the rim mating surface are determined. 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 and C2 and the midpoint 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.

[0070] 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), determined.

[0071] 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 conventional tire structure including bead filler. Accordingly, the rates of change ΔG1, ΔG2, ΔGm of change of the rim fitting section are manufactured appropriately. This means that the lower limit ensures the correct rim pressure and guarantees the tire fits the rim. Furthermore, the upper limit prevents excessive rim pressure from impairing the tire's mounting process on the rim.

[0072] Using the thicknesses Gi and Gi' before and after mounting on the rim at the previously defined measuring points, a rate of change ΔGi is determined as ΔGi = (Gi - Gi') / Gi × 100. For example, using the thickness G1 (see Fig. 3) before mounting on the rim and the thickness G1' (see Fig. 5) After mounting on the rim, the rate of change ΔG1 is calculated as ΔG1 = (G1 - G1') / G1 × 100.

[0073] The change rates ΔG1, ΔG2, ΔGm of the rim pass section described above are, for example, achieved by a configuration of a cushioning rubber layer 20 described later (see Fig. 6) and a configuration of a cone angle of the bead base Bb (see Fig. 7) received.

[0074] Additionally, the rates of change ΔG1, ΔG2, ΔGm of the rim pass section preferably satisfy the condition |ΔGm - ΔG2| < |ΔG1 - ΔGm|. Accordingly, a difference in the rate of change |ΔG1 - ΔGm| at the bead toe Bt is greater than a 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 satisfy the condition 30% ≤ |(ΔG1 - ΔGm) / (ΔGm - ΔG2)| ≤ 300%. Thus, the relationship between the rates of change ΔG1, ΔG2, ΔGm of the rim fit section is appropriately established. That is, the lower limit improves the rim fit of the tire. Furthermore, the upper limit improves the ease of mounting the tire onto the rim.

[0075] 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. This improves the rim fit of the tire.

[0076] Furthermore, the thicknesses G1, G2, Gm of the rim pass section of the tire, in the state before the tire is mounted, indicate the rim in the configuration of Fig. 3, a ratio G2 < Gm < G1. In other words, the thicknesses G1, G2, Gm of the rim mating section increase towards the bead point Bt. Thus, the mutual relationship between the rates of change ΔG1, ΔG2, ΔGm is suitably established. Furthermore, in 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. Likewise, the thickness G2 is preferably in the range 1.0 mm ≤ G2 and more preferably in the range 2.0 mm ≤ G2. Thus, the rubber volume of the rim mating section is suitably established from the bead cores 11 inwards in the radial direction.

[0077] Furthermore, they have 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 have a ratio of 1.0%·mm / inch ≤ Wc2 × ΔGm / RD ≤ 50%·mm / inch, more preferably have a ratio of 2.0%·mm / inch ≤ Wc2 × ΔGm / RD ≤ 40%·mm / inch, and more preferably have a ratio of 5.0%·mm / inch ≤ Wc2 × ΔGm / RD ≤ 30%·mm / inch. Thus, the ratio between the width Wc2 of the innermost layer of the bead cores 11 and the rate of change ΔGm is suitably established. That is, the lower limit ensures the rim fit of the tire. Furthermore, the upper limit improves the ease of mounting the tire onto the rim.

[0078] 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.

[0079] Furthermore, the width Wc2 of the innermost layer of 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

[0080] As in Fig. As illustrated in Figure 4, the bead cores 11 are formed by ring-shaped, multi-layered winding of the tire bead wires 111 and exhibit the previously defined 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 tire bead wires 111. Furthermore, the wire arrangement structure is formed by a plurality of layers stacked in the tire radial direction. These layers are formed from the plurality of wire cross-sections arranged in a row in the tire transverse direction. In addition, 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 surface structure 101 of the rim 10 when the tire is fitted to the rim (see Figure 4). Fig. 3).

[0081] In one manufacturing process for the bead cores 11, a core forming template (not illustrated) is used, and one or more tire 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 pre-vulcanized prior to a vulcanization forming step of a raw tire. It should be noted that no such restriction is provided, and the pre-vulcanization 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.

[0082] Furthermore, the tire 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 is preferably made of a rubber compound with a Mooney viscosity of 70 M or higher. The Mooney viscosity is calculated according to JIS K6300-1:2013.

[0083] In the configuration of Fig. 2. As described above, the folded section 132 of the carcass layer 13 contacts the body part 131 of the carcass layer 13 to form the closed area X, which surrounds the bead cores 11. Furthermore, the rubber layup ratio in the closed area X is set to be low in order to reduce the weight of the bead section. At the same time, to increase the durability of the bead section, a void section in the closed area X is preferably suppressed.

[0084] 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, a layer is shown 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 determined 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) Furthermore, the number of wire cross-section arrangements in each layer decreases monotonically from the maximum arrangement layer outwards in the tire radial direction. 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 in 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.

[0085] 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 layer. 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 collapse resistance of the bead cores 11 is improved compared to a grid arrangement structure in which rows of wire cross-sections are perpendicular vertically and horizontally.It should be noted that in the densest packed state it is not necessary for all groups of adjacent wire cross-sections to come into contact with each other and some groups can be arranged with narrow gaps (not illustrated).

[0086] In such a configuration, as in Fig. As illustrated in Figure 3, the body part 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 they abut the right and left side surfaces of the bead cores 11 in the tire transverse direction and are joined in a Y-shape to come into contact with each other. This reduces the gap between the connecting section of the body part 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, 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.Furthermore, the amount of the overwrap 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 part 132.

[0087] 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.

[0088] As in the Fig. As illustrated in Figure 4, the arrangement angles θ1, θ2 of the wire cross-sections at corner sections are determined 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 lie in the range 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. Similarly, if the arrangement angles θ1, θ2 of the wire cross-sections are obtuse, the carcass ply along the corner sections can be folded inwards 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.

[0089] 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.

[0090] Furthermore, 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 tire bead wires 111 in the bead cores 11 preferably have a ratio of 1.20 ≤ Wc1 × Hc1 / S ≤ 5.00, more preferably a ratio of 1.50 ≤ Wc1 × Hc1 / S ≤ 4.50, and more preferably a ratio of 1.80 ≤ Wc1 × Hc1 / S ≤ 4.00. This ensures a suitable wire arrangement structure for the bead cores 11. That is, the lower limit ensures the number of wire cross-sectional arrangements and guarantees the tire's rim fit. Furthermore, the upper limit reduces the weight of the bead cores 11.

[0091] It should be noted that the total cross-sectional area S of the tire bead wires does not include the cross-sectional area of ​​the insulating rubbers.

[0092] Furthermore, the total cross-sectional area S of the tire bead wires 111 is preferably in the range of 5 mm. 2 ≤ S ≤ 35 mm2 , preferably in the 6 mm range 2 ≤ S ≤ 32 mm 2 and even more so in the 7 mm range 2 ≤ S ≤ 28 mm 2 Thus, the total cross-sectional area S of the tire bead wires 111 is appropriately manufactured. In particular, the lower limit ensures the total cross-sectional area S of the tire bead wires 111 and guarantees the rim fit of the tire. Furthermore, the upper limit reduces the weight of the bead cores 11.

[0093] Furthermore, there is an outer diameter φ (see Fig. 4) of the tire 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 tire bead wire 111 is suitably produced. That is, the lower limit ensures the outer diameter φ of the tire bead wire 111 and guarantees the rim fit of the tire. Furthermore, the upper limit reduces the weight of the bead cores 11.

[0094] Furthermore, 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 have a ratio of 1.10 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.80 and preferably a ratio of 1.30 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.50 and more preferably a ratio of 1.50 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.30. Thus, the wire arrangement structure of the bead cores 11 is suitably produced.

[0095] The maximum height Hc1 of the bead cores is measured as the maximum height of the bead cores from the tangent line L1.

[0096] 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.

[0097] For example, in the configuration of 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 from the innermost layer in the tire radial direction. Thus, the number of wire cross-section arrangements in the maximum arrangement layer is four. Furthermore, the number of wire cross-section layers extending outwards in the tire radial direction with respect to the maximum arrangement layer is three, and the number of wire cross-section layers extending inwards in the tire radial direction with respect to the maximum arrangement layer is one. Accordingly, the maximum arrangement layer is asymmetrical in the tire radial direction and is 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 long structure extending outwards in the tire radial direction from the maximum arrangement layer.Furthermore, the number of wire cross-sections in each layer decreases successively from the layer with the highest density outwards in the tire radial direction. All wire cross-sections are also arranged in the densest packed structure. Thus, 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 layer with the highest density of wire cross-sections is not the innermost layer in the tire radial direction. In addition, the number of wire cross-sections in each layer successively increases from the innermost layer to the layer with the highest density. This optimizes the wire arrangement structure.

[0098] Furthermore, it points out that Fig. 3. A distance Hg in the tire radial direction from the end section outwards from the bead cores 11 in the tire radial direction to the contact section between the body part 131 and the folded-over section 132 of the carcass layer 13 preferably has a ratio Hg / φ ≤ 7.0 to the outer diameter φ of the tire bead wire 111 and more preferably has a ratio Hg / φ ≤ 3.0. This improves the stiffness around the bead cores 11. It should be noted that the lower limit of the ratio Hg / φ is 0 ≤ Hg / φ in the case Hg = 0. Thickness of the rim pass section

[0099] Fig. 6 is an explanatory diagram that illustrates the Fig. 3 illustrated rim fitting section. The same drawing illustrates the rim fitting section in the state before mounting it on the rim. In the same drawing are components which are the same as those in Fig. The three illustrated components are labelled with the same reference symbols, and their explanations are omitted.

[0100] In Fig. 6. As described above, the thickness G2 in the tire radial direction is determined from the contact point C2 between the tangent line L1 of the innermost layer of the wire arrangement structure and the outermost wire cross-section in the tire transverse direction up to the rim mating surface. At this point, the thickness G2 and the outer diameter φ (see Fig. 4) The thickness of the tire 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. This ensures that the thickness G2 of the rim fitting section is appropriately produced. 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 any deterioration in the processability of mounting the tire onto the rim due to excessive thickness G2 of the rim fitting pressure.

[0101] Furthermore, in Fig. 6. An intersection point Q is determined 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. Likewise, a thickness W in the tire's transverse direction is determined from the contact point C2 of the bead core 11 to point Q on the rim fitting surface. At this point, the thickness Wh and the outer diameter φ (see Fig. 4) The tire 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. Thus, the thickness Wh of the rim fitting section is suitably produced. That is, the lower limit ensures the thickness Wh of the rim fitting section, it ensures the rim fit of the tire, and it ensures the durability of the rim fitting section. Furthermore, the upper limit prevents a deterioration in the processability of mounting the tire onto the rim due to excessive thickness Wh of the rim fitting pressure.

[0102] Furthermore, as in Fig. As illustrated 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 cushioning rubber layer 20 is a component 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) that joins the inner liner 18 and the carcass layer 13, but does not include the carcass layer. Furthermore, the cushioning rubber 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). Additionally, the cushioning rubber layer 20 can be made of the same rubber material as the inner liner 18 and the connecting rubber described above, or it can be made of a different rubber material (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.

[0103] Furthermore, the rubber hardness of the cushioning rubber layer 20 is preferably five or more, and more preferably eight or more, lower than the rubber hardness of the wheel rim cushioning rubber 17. Thus, the effect of increasing the rates of change ΔG1, ΔG2, ΔGm of the rim profile section is appropriately preserved.

[0104] For example, in the configuration of Fig. Figure 6 shows the cushioning rubber layer 20 in the tire meridional direction, extending from the tire cavity surface outwards in the tire transverse direction along the folded-over section 132 of the carcass layer 13 and inserted between the bead cores 11 and the rim cushioning rubber 17. The cushioning rubber layer 20 also extends beyond the center point Cm of the innermost layer of the bead cores 11 to the outermost contact point C2. Furthermore, the end section of the cushioning rubber layer 20 terminates blindly 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 from the bead cores 11 to the side surface in the tire transverse direction.Thus, the rates of change ΔG1, ΔG2, 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.

[0105] Furthermore, in Fig. 6. The thicknesses Tc1, Tc2 of the cushioning rubber layer 20 between measuring points C1 and P1; and C2 and P2 of the thicknesses G1, G2 of the rim fitting section preferably exhibit a ratio Tc2 < Tc1. In other words, the thickness Tc1 of the cushioning rubber layer 20 on the bead toe side Bt is preferably greater 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.

[0106] 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 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.

[0107] Furthermore, the average thickness of the cushioning rubber layer 20 in the area in the transverse direction of the tire from contact point C1 to contact point C2 is preferably in the range of 0.3 mm or more to 3.0 mm or less. Thus, the average thickness of the cushioning rubber layer 20 is suitably determined. In other words, the lower limit appropriately preserves the effect of the cushioning rubber layer 20, which 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.

[0108] Furthermore, 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. Thus, the average thickness of the cushioning rubber layer 20 is suitably produced. That is, the lower limit ensures the effectiveness 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 ensures the rim fit of the tire.

[0109] Furthermore, 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

[0110] Fig. 7 is an explanatory diagram that illustrates the Fig. 3 illustrated rim fitting section. The same drawing illustrates the rim fitting section in the state before mounting it on the rim. In the same drawing are components which are the same as those in Fig. The three illustrated components are labelled with the same reference symbols, and their explanations are omitted.

[0111] As in Fig. Figure 7 illustrates a tangent line of the rim mating 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.

[0112] 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.

[0113] 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 have a ratio of 0%·degrees ≤ ΔGm × a / WA ≤ 7%·degrees, and more preferably a ratio of 0.5%·degrees ≤ ΔGm × a / WA ≤ 5.0%·degrees. Thus, a ratio ΔGm × a / WA, which indicates the rim fit of the tire, is suitably produced. In other words, generally, as the nominal tire width WA increases, the rim fit of the tire tends to decrease. 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 × a / WA and improves the tire's rim fit.Furthermore, the upper limit prevents a deterioration in the workability of mounting the tire onto the rim due to excessive contact pressure. It should be noted that if the inclination angle a = 0 degrees, ΔGm × a / WA = 0 is satisfied.

[0114] Furthermore, as in Fig. Figure 7 illustrates, 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 bead base Bb of the rim mating surface.

[0115] At this point, the inclination angles a, 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 have a ratio of 0 ≤ β / a ≤ 5.0 and more preferably have a ratio of 1.8 ≤ β / a ≤ 4.0. Thus, the two-stage conical shape of the bead base Bb is suitably produced. In other words, the lower boundary appropriately achieves the effect of improving the rim fit of the tire, which is achieved by the two-stage conical shape. Furthermore, the upper boundary suppresses the occurrence of a vulcanization defect in the bead base Bb.

[0116] Furthermore, in Fig. 7 the intersection point R of the two types of linear sections of the bulge base Bb is determined.

[0117] 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 have a ratio of 0.50 ≤ Lr / Lm ≤ 4.0 and more preferably have a ratio of 0.70 ≤ Lr / Lm ≤ 3.3. Thus, the position of the intersection point R is suitably established, and the effect of improving the rim fit of the tire, achieved by the two-stage conical shape, is appropriately maintained.

[0118] For example, the configuration of 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 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. Likewise, the intersection point R is located between the contact point C1 and the center point Cm of the bead cores 11.

[0119] In Fig. 7. A distance Dt in the tire radial direction from the contact point C1 of the bead cores 11 to the bead point Bt and a distance Wt in the tire transverse direction are determined. 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 have a ratio of 7 degrees ≤ arctan {(Dt - G1) / Wt} ≤ 30 degrees and more preferably have a ratio of 9 degrees ≤ arctan {(Dt - G1) / Wt} ≤ 25 degrees. Thus, a gradient of the rim mating surface with respect to the tire axial direction from the bead cores 11 to the bead point 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 suppresses a decrease in the processability of mounting the tire onto the rim due to the excessive gradient of the rim mating surface.

[0120] The distances Dt from contact point C1 to bead Bt and the distance Wt are measured in the state before the tire is mounted on the rim. Modified examples

[0121] 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 demonstrate this. These drawings illustrate a cross-sectional view of the unvulcanized bead cores 11 in the radial direction when the components are separate.

[0122] In the configuration of Fig. 4. The tangent line L1 to the innermost layer of the bead cores 11 runs parallel to the tire's transverse direction. Accordingly, the angle of inclination X of the tangent line L1 with respect to the tire's transverse direction X = 0 degrees.

[0123] However, no such restriction is intended, and as in Fig. As illustrated in Figure 8, the bead cores 11 can be 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 stem 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.

[0124] Furthermore, the configuration of Fig. 4. As described above, the number of wire cross-section arrangements in the sequence from the innermost layer in the tire radial direction is set to 3-4-3-2-1. Thus, the number of layers of wire cross-sections is five, and the number of wire cross-section arrangements in the outermost layer in the tire radial direction is one.

[0125] In contrast, in the configuration of Fig. 9. The number of layers of wire cross-sections is four, and the number of arrangements of wire cross-sections is set in the sequence from the innermost layer in the tire radial direction to 3-4-3-2. In the Fig. In the illustrated configuration 10, the number of wire cross-section layers is six, and the number of wire cross-section arrangements is set in the order from the innermost layer in the tire radial direction to 3-4-5-4-3-2. Thus, 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 the 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). In addition, the number of wire cross-section arrangements in each layer decreases successively from the maximum arrangement layer outwards in the tire radial direction.

[0126] Furthermore, the configuration of 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). Likewise, all wire cross-sections forming the wire arrangement structure are arranged in the most densely packed structure. Thus, both arrangement angles θ1, θ2 of the wire cross-sections at the corner sections lie in the range of 130 degrees or more to 140 degrees or less, both inwards in the tire radial direction and inwards and outwards in the tire transverse direction.

[0127] In contrast, in the configuration of Fig. 11 and Fig. 12. The number of wire cross-section layers is five, and the number of wire cross-section arrangements is set to 4-4-3-2-1 in the radial direction of the tire, starting from the innermost layer. 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. Furthermore, in the configuration of Fig. 11. The arrangement angle θ1 of the wire cross-sections at the corner section 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-sections at the corner section 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, facing inwards in the tire radial direction of the wire arrangement structure, are substantially right angles and lie in the range of 85 degrees or more to 95 degrees or less. In this manner, at least the arrangement angle θ2 of the wire cross-sections at the corner section, facing outwards in the tire transverse direction, preferably has 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

[0128] 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 meridian direction at a tire's maximum width position A.

[0129] In Fig. 13. The total thickness K1 of the tire sidewall section at the maximum tire 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. Thus, the total thickness K1 of the tire sidewall section is suitably achieved. That is, the lower limit ensures the total thickness K1 of the tire sidewall section and provides sufficient tire rolling resistance. Likewise, the upper limit ensures the reduction of the tire's weight.

[0130] The total thickness K1 of the tire sidewall section is measured as a distance in the tire transverse direction between the inner tire surface and the outer tire surface at the tire maximum width position A in the cross-sectional view in the tire meridian direction.

[0131] Furthermore, the thickness K2 of a sidewall rubber 16 at the tire's 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. Thus, the thickness K2 of the sidewall rubber 16 is suitably manufactured. That is, the lower limit ensures the thickness K2 of the sidewall rubber 16 and guarantees cut resistance of the tire sidewall section. Likewise, the upper limit ensures weight reduction of the tire.

[0132] Furthermore, the thickness K2 of the sidewall rubber 16 at the tire's maximum width position A and the tire thickness Wo from the carcass layer 13 outwards in the tire's transverse direction at the radial position, which is twice the radial height H1 of the bead cores 11, preferably have a ratio of 0.10 ≤ K2 / Wo ≤ 3.00, more preferably a ratio of 0.25 ≤ K2 / Wo ≤ 2.50, and even more preferably a ratio of 0.35 ≤ K2 / Wo ≤ 2.00. Thus, the thickness K2 of the sidewall rubber 16 is suitably produced. That is, the lower limit ensures cut resistance. Likewise, the upper limit ensures weight reduction of the tire. Overlap between the end section of the carcass layer and the belt layer

[0133] Fig. 14 is an enlarged view showing a shoulder section of the Fig. 1 illustrated pneumatic tire.

[0134] In the configuration of Fig. 1. As described above, the folded-over section 132 of the carcass layer 13 extends outwards in the tire radial direction beyond the tire maximum width position A. Furthermore, as described in Fig. Figure 14 illustrates that the end section (reference symbol omitted in the drawing) of the folded section 132 is held in place by being sandwiched between the body part 131 of the carcass layer 13 and the innermost layer of the belt layer 14 (the cross belt 141 on the inner diameter side in Fig. 14) is arranged. This increases the tension of the carcass layer 13 and improves the rim fit of the tire.

[0135] At this point, the overlap width Wra between the folded-over section 132 of the carcass layer 13 and the innermost layer of the belt layer 14 in the transverse direction of the tire is preferably in the range of 0 mm ≤ Wra ≤ 30 mm and more preferably in the range of 5 mm ≤ Wra ≤ 30 mm. Thus, the overlap width Wra between the folded-over section 132 of the carcass layer 13 and the belt layer 14 is suitably achieved. That is, the lower limit ensures a suitable rim fit of the tire, and the upper limit prevents a deterioration of the tire's uniformity. Effects

[0136] As described above, the pneumatic tire 1 includes the bead cores 11, the carcass layer 13, and the rim pad rubber 17. The bead cores 11 are formed by ring-shaped and multi-layered winding of one or more tire bead wires 111. The carcass layer 13 is formed from the carcass ply, consisting 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 pad 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) The folded-over section 132 of the carcass layer 13 comes into contact with the body part 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 in the range of 15% or less. The bead cores 11 have the previously defined wire arrangement structure, which is formed by arranging the wire cross-sections of the tire bead wires 111 in the cross-sectional view in the tire meridional direction (see Fig. 4) Furthermore, the self-contact height CH of the carcass layer 13 and the circumferential length L (dimension symbol omitted in the drawing) of the wire arrangement structure have the ratio 1.0 ≤ CH / L ≤ 10.0 (see Fig. 1).

[0137] In such a configuration, (1) the rubber volume ratio in the closed area X, which is surrounded by the body part 131 and the folded section 132 of the carcass layer 13, i.e., the rubber volume around the bead cores 11, is set significantly low. This has the advantage that bead fillers can be omitted and the weight of the tire is reduced. Furthermore, (2) the CH / L ratio provides the advantage of ensuring a suitable self-contact height CH of the carcass layer 13. In other words, the lower limit ensures that the folded section 132 makes stable contact with the body part 131, thereby ensuring the stiffness of the bead section and guaranteeing the rim fit of the tire and the durability of the bead section. Moreover, the upper limit prevents an increase in tire weight due to an excessive amount of the folded section 132.It should be noted that, since the amount of the increase in tire weight due to the increase in self-contact height CH is much smaller than the amount of the reduction in tire weight due to the omission of bead fillers described above, the weight reduction of the tire is also achieved appropriately in the configuration described above.

[0138] Furthermore, in the pneumatic tire 1 according to the embodiment of the present invention, the circumferential length L of the wire arrangement structure and the tire cross-sectional height SH (see Fig. 1) The ratio 0.12 ≤ L / SH ≤ 1.00. This has the advantage that the circumferential length L of the bead cores 11 is appropriately manufactured. That is, the lower limit ensures the circumferential length L of the bead cores 11 and guarantees the rim fit of the tire. In addition, the upper limit prevents an increase in tire weight due to an excessive number of bead cores 11.

[0139] Furthermore, in the pneumatic tire 1 according to the embodiment of the invention, the tire cross-sectional height SH and the self-contact height CH of the carcass layer 13 have a ratio of 2.4 mm ≤ SH - CH ≤ 135 mm (see Fig. 1) This has the advantage that the difference between the tire cross-sectional height SH and the self-contact height CH of the carcass layer 13 is appropriately produced.

[0140] Furthermore, in the pneumatic tire 1 according to the embodiment of the present invention, the self-contact height CH and the folded-over height PH (see Fig. 1) The carcass layer 13 and the tire aspect ratio HF are set to the ratio 0.60 × (HF / 100) ≤ CH / PH ≤ 0.98. This has the advantage that the CH / PH ratio is appropriately produced. That is, the lower limit ensures the ratio of the self-contact height CH to the folded height PH of the carcass layer 13 and guarantees the rim fit of the tire. In addition, the upper limit prevents an increase in tire weight due to an excessive amount of the folded section 132.

[0141] Furthermore, in the pneumatic tire 1 according to the embodiment of the present invention, the tire thickness Wo outwards in the tire transverse direction and the tire thickness Wi inwards in the tire transverse direction of the carcass layer 13 at the radial positions, which are twice the radial height H1 of the bead cores 11, have the ratio 3.0 mm ≤ Wo + Wi ≤ 20 mm (see Fig. 2) This has the advantage that the tire thicknesses inside and outside the carcass layer 13 are appropriately manufactured in the radial direction from the bead cores 11 outwards. In particular, the lower limit ensures the tire thicknesses in this area and guarantees the tire's rim fit. Furthermore, the upper limit prevents an increase in tire weight due to excessive tire thickness.

[0142] Furthermore, in the pneumatic tire 1 according to the embodiment of the present invention, the tire thickness Wo outwards in the tire transverse direction and the tire thickness Wi inwards in the tire transverse direction of the carcass layer 13 have the ratio 1.0 ≤ Wo / Wi ≤ 10.0 at the radial positions, which are twice the radial height H1 of the bead cores 11 (see Fig. 2) This has the advantage that the tire thicknesses inside and outside the carcass layer 13 are appropriately manufactured in the radial direction from the bead cores 11 outwards. Therefore, the lower limit ensures the tire thickness Wo from the carcass layer 13 outwards in the transverse direction of the tire and guarantees the rim fit of the tire. In addition, the upper limit prevents an increase in tire weight due to excessive tire thickness.

[0143] Furthermore, for pneumatic tire 1, the total thickness K1 of the tire sidewall section at the maximum tire width position A is in the range of 2.5 mm ≤ K1 ≤ 6.5 mm (see Fig. 13) This has the advantage that the overall thickness K1 of the tire sidewall section is appropriately manufactured. That is, the lower limit ensures the overall thickness K1 of the tire sidewall section and guarantees tire rolling resistance. Likewise, the upper limit ensures the weight reduction of the tire.

[0144] Furthermore, in the case of the pneumatic tire 1, the thickness K2 of the sidewall rubber 16 at the tire's maximum width position A is in the range of 0.3 mm ≤ K2 ≤ 3.0 mm (see Fig. 13) This has the advantage that the overall thickness K2 of the sidewall rubber 16 is appropriately manufactured. That is, the lower limit ensures the thickness K2 of the sidewall rubber 16 and guarantees cut resistance of the tire sidewall section. Likewise, the upper limit ensures weight reduction of the tire.

[0145] Furthermore, the pneumatic tire 1 has a thickness K2 (see Fig. 13) of the sidewall rubber 16 at the tire maximum width position A and the tire thickness Wo (see Fig. 2) From the carcass layer 13 outwards in the transverse direction of the tire at the radial position, which is twice the radial height H1 of the bead cores 11, the ratio 0.10 ≤ K2 / Wo ≤ 3.00 is applied. Thus, the thickness K2 of the sidewall rubber 16 is appropriately produced. That is, the lower limit ensures cut resistance. Likewise, the upper limit ensures weight reduction of the tire.

[0146] Furthermore, in pneumatic tire 1, the arrangement angle θ2 of the wire cross-sections at the corner section lies in the range of 80 degrees ≤ θ2, both inwards in the tire radial direction and outwards in the tire transverse direction. This has the advantage that interruption of the wire arrangement structure during tire vulcanization is suppressed and the durability of the bead section is improved.

[0147] Furthermore, in the pneumatic tire 1 according to the embodiment of the present invention, the folded-over section 132 of the carcass layer 13 extends outwards in the tire radial direction beyond the tire maximum width position A (see Fig. 1) This has the advantage of increasing the tension of the carcass layer 13 and improving the rim fit of the tire.

[0148] Furthermore, according to the embodiment of the present invention, the pneumatic tire 1 includes the belt layer 14, which is arranged outwards from the carcass layer 13 in the tire radial direction (see Fig. 1) Furthermore, the folded-over section 132 of the carcass layer 13 is arranged in such a way that it is sandwiched between the carcass layer 13 and the innermost layer of the belt layer 14 (see Fig. 14). Furthermore, the overlap width Wra between the folded section 132 of the carcass layer 13 and the innermost layer of the belt layer 14 in the transverse direction of the tire lies in the range 0 mm < Wra ≤ 30 mm. This has the advantage that the overlap width Wra between the folded section 132 of the carcass layer 13 and the belt layer 14 is appropriately produced. That is, the lower limit ensures a suitable rim fit of the tire, and the upper limit prevents a deterioration of the tire's uniformity.

[0149] 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 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.

[0150] Furthermore, in the case of the pneumatic tire 1, the outer diameter φ of the tire bead wire 111 is (see Fig. 4) within a range of 0.8 mm ≤ φ ≤ 1.5 mm. This ensures that the outer diameter φ of the tire bead wire 111 is appropriately manufactured. That is, the lower limit guarantees the outer diameter φ of the tire bead wire 111 and ensures the tire fits the rim. Furthermore, the upper limit reduces the weight of the bead cores 11.

[0151] Furthermore, in the pneumatic tire 1, there is a layer in which the number of arrangements of wire cross-sections in the wire arrangement structure is greatest (in Fig. 4. The second layer from the innermost layer) is determined 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) Furthermore, the number of wire cross-section arrangements in each layer decreases outwards in the tire radial direction relative to the maximum arrangement layer (see Fig. 4) monotonically. This has the advantage that the gap between the connection section of the body part 131 with the folded section 132 of the carcass layer 13 and the upper section (the so-called bead roof) from the bead cores 11 outwards in the tire radial direction becomes small, 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 layup ratio in the closed area X can be reduced. Additionally, the amount of fold of the folded section 132 is reduced, and the durability of the bead section is improved, since the folded section 132 can fold at an obtuse angle at the connection point with the body part 131. Example

[0152] Fig. Figure 15 is a table showing results of performance tests of pneumatic tires according to the embodiments of the present invention. Fig. Figure 16 is an explanatory diagram illustrating the bead cores of a test tire representing a state-of-the-art example.

[0153] In the performance test, a plurality of test tire types with a tire size of 205 / 55R16 are evaluated with regard to (1) tire mass and (2) rim fit.

[0154] (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. Furthermore, 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 that include bead fillers.

[0155] (2) In the evaluation of rim fit, the test tires are mounted on rims with a rim size of 16 × 6.5 J and inflated to a pressure of 230 kPa. A load specified by JATMA is applied. The test tires are mounted on an off-road vehicle (SUV) with a 2000 cc engine. The test vehicle then performs a J-turn on a predetermined route while the tire pressures are gradually reduced, and the 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). Higher values ​​are preferred in this evaluation.

[0156] The test tires in examples 1 to 9 achieve the weight reduction of the tires by having the structures with omitted bead fillers (see Fig. 1 and Fig. 2).

[0157] In the test tires of the state of the art example, the self-contact height CH of the carcass layer 13 is set so that it is small in the configuration of the test tire of example 1.

[0158] As the test results show, the test tires of examples 1 to 9 can improve the rim fit and the steering stability of the tire, while reducing the weight of the tires. List of reference symbols 1 pneumatic tire 11 bead core 111 Tire bead wire 13 Carcass layer 131 Body part 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 bulge-like structures 102 Flange

Claims

[1] Pneumatic tires (1), comprising: Bead cores (11) formed by ring-shaped and multi-layered winding of one or more tire bead wires (111); a carcass layer (13) formed from a carcass layer consisting 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 to extend 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 part (131) of the carcass layer (13) in a cross-sectional view in the tire meridian direction to form a closed area (X) surrounding the bead cores (11); a rubber covering ratio in the closed area (X) which is in a range of 15% or less, wherein the rubber covering ratio is a percentage of a 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 meridional direction; wherein the bead cores (11) have a predetermined wire arrangement structure formed by arranging wire cross sections of the tire bead wires (111) in the cross-sectional view in the tire meridian direction; wherein in the cross-sectional view external tangents to the tire bead wires (111) at outer circumferential surfaces of the bead cores (11) form a polygon that surrounds the wire arrangement structure, wherein a circumferential length of the polygon is a circumferential length L of the wire arrangement structure; wherein a self-contact height CH of the carcass layer is a maximum height of a contact section between the body part (131) and the folded-over section (132) of the carcass layer (13) in the tire radial direction; and the self-contact height CH of the carcass layer (13) and the circumferential length L of the wire arrangement structure, which have a ratio 1.0 ≤ CH / L ≤ 10.

0. [2] Pneumatic tire (1) according to claim 1, wherein the circumferential length L of the wire arrangement structure and a tire cross-sectional height SH have a ratio 0.12 ≤ L / SH ≤ 1.

00. [3] Pneumatic tire (1) according to claim 1 or 2, wherein a tire cross-sectional height SH and the self-contact height CH of the carcass layer (13) have a ratio of 2.4 mm ≤ SH - CH ≤ 135 mm. [4] Pneumatic tire (1) according to any one of claims 1 to 3, wherein the self-contact height CH and a folded height PH of the carcass layer (13) and a tire aspect ratio HF have a ratio 0.60 x (HF / 100) ≤ CH / PH ≤ 0.

98. [5] Pneumatic tire (1) according to any one of claims 1 to 4, wherein a tire thickness Wo outwards in the transverse direction of the tire and a tire thickness Wi inwards in the transverse direction of the carcass layer (13) at radial positions which are twice a radial height H1 of the bead cores (11) have a ratio 3.0 mm ≤ Wo + Wi ≤ 20 mm. [6] Pneumatic tire (1) according to any one of claims 1 to 5, wherein a tire thickness Wo outwards in the transverse direction of the tire and a tire thickness Wi inwards in the transverse direction of the carcass layer (13) at radial positions which are twice a radial height H1 of the bead cores (11) have a ratio 1.0 ≤ Wo / Wi ≤ 10.

0. [7] Pneumatic tire (1) according to any one of claims 1 to 6, wherein a total thickness K1 of a tire side section at a tire maximum width position is in a range of 2.5 mm ≤ K1 ≤ 6.5 mm. [8] Pneumatic tire (1) according to any one of claims 1 to 7, wherein a thickness K2 of a sidewall rubber (16) at a tire maximum width position is in the range 0.3 mm ≤ K2 ≤ 3.0 mm. [9] Pneumatic tire (1) according to any one of claims 1 to 8, wherein a thickness K2 of a sidewall rubber (16) at a tire maximum width position and a tire thickness Wo from the carcass layer (13) outwards in the tire transverse direction at a radial position which is twice a radial height H1 of the bead cores (11) have a ratio 0.10 ≤ K2 / Wo ≤ 3.

00. [10] Pneumatic tire (1) according to any one of claims 1 to 9, wherein an arrangement angle θ2 of the wire cross sections at a corner section is 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. [11] Pneumatic tire (1) according to any one of claims 1 to 10, wherein the folded-over section (132) of the carcass layer (13) extends outwards in the tire radial direction beyond a tire maximum width position. [12] Pneumatic tire (1) according to any one of claims 1 to 11, comprising a belt layer (14) arranged outwards from the carcass layer (13) in the tire radial direction, wherein the folded section (132) of the carcass layer (13) is arranged in such a way that it is sandwiched between the carcass layer (13) and an innermost layer of the belt layer (14), and an overlap width Wra between the folded section (132) of the carcass layer (13) and the innermost layer of the belt layer (14) in the tire transverse direction is in a range 0 mm < Wra ≤ 30 mm. [13] Pneumatic tire (1) according to any one of claims 1 to 12, wherein a height Hc2 from a tangent line L1 to a maximum width position of the bead cores (11) and a maximum height Hc1 of the bead cores (11) have a ratio 1.10 ≤ (Hc1 - Hc2) / Hc2 ≤ 2.

80. [14] Pneumatic tire according to any one of claims 1 to 13, wherein an outer diameter φ of the tire bead wire (111) is in a range of 0.8 mm ≤ φ ≤ 1.5 mm. [15] Pneumatic tires (1) according to claim 1 or 2, 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 wire cross-sections outwards in the tire radial direction with respect to the maximum arrangement layer is greater than a number of layers of wire cross-sections inwards in the tire radial direction with respect to the maximum arrangement layer and The number of wire cross-section arrangements in each layer decreases monotonically outwards in the tire radial direction relative to the maximum arrangement layer.

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