Tire

Abstract

The tire outer diameter OD [mm] of the tire 1 of the present application is in the range of 200 ≤ OD ≤ 660, and the total tire width SW [mm] is in the range of 100 ≤ SW ≤ 400. Furthermore, the carcass layer (13) is made by laminating two carcass plies (13A, 13B) made of coating organic fiber cords with coating rubber. Furthermore, the organic fiber cords of the two carcass plies (13A, 13B) have cord angles in the range of 80 [deg] or more and 100 [deg] or less with respect to the tire circumferential direction. Furthermore, the breaking strength Tcs [N / 50 mm] per 50 [mm] width of each of the two carcass plies (13A, 13B) is in the range of 17 ≤ Tcs / OD ≤ 120 with respect to the tire outer diameter OD [mm].

Description

Technical Field

[0001] This invention relates to a tire, and more specifically, to a small-diameter tire that can balance low rolling resistance and wear resistance. Background Technology

[0002] In recent years, small-diameter tires have been developed for use on vehicles with lowered floors to increase interior space. These small-diameter tires have lower rotational inertia and lighter weight, thus potentially reducing transportation costs. On the other hand, small-diameter tires require high load-bearing capacity. As a conventional tire related to this issue, the technology described in Patent Document 1 is known.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2020 / 122169 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The purpose of this invention is to provide a small-diameter tire that can balance low rolling resistance and wear resistance.

[0008] Technical means to solve the problem

[0009] To achieve the above objectives, the tire of the present invention comprises a pair of bead cores, a carcass layer mounted on the bead cores, and a belt layer disposed radially outward of the carcass layer, and is characterized in that the tire outer diameter OD [mm] is in the range of 200≤OD≤660, the tire total width SW [mm] is in the range of 100≤SW≤400, the carcass layer is formed by stacking two carcass ply layers made of organic fiber cords coated with coated rubber, the organic fiber cords of the two carcass ply layers having a cord angle in the range of 80 [deg] or more and 100 [deg] or less relative to the tire circumference, and the breaking strength Tcs [N / 50mm] of each of the two carcass ply layers per 50 [mm] width is in the range of 17≤Tcs / OD≤120 relative to the tire outer diameter OD [mm].

[0010] Furthermore, the tire of the present invention comprises a pair of bead cores and a carcass layer mounted on the bead cores, and is characterized in that the tire outer diameter OD [mm] is in the range of 200≤OD≤660, the tire total width SW [mm] is in the range of 100≤SW≤400, the carcass layer is formed by stacking two carcass ply layers made of organic fiber cords coated with coated rubber, the organic fiber cords of the two carcass ply layers have cord angles that are different from each other and are in the range of 45 [deg] or more and 70 [deg] or less relative to the tire circumference, and the breaking strength Tcs [N / 50mm] of each 50 [mm] width of the two carcass ply layers is in the range of 17≤Tcs / OD≤120 relative to the tire outer diameter OD [mm].

[0011] Invention Effects

[0012] In the tire of this invention, the small-diameter tire can adequately ensure the load-bearing capacity of the carcass layers, thus possessing the advantage of balancing tire wear resistance and low rolling resistance. Specifically, by using the aforementioned lower limit ratio Tcs / OD, tire deformation under high loads can be suppressed, thereby ensuring tire wear resistance. By using the aforementioned upper limit ratio Tcs / OD, the decrease in rolling resistance caused by the increase in the mass of the carcass layers can be suppressed. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of the tire along the radial direction according to an embodiment of the present invention.

[0014] Figure 2 It means Figure 1 The enlarged image of the tire recorded in the document.

[0015] Figure 3 It means Figure 1 The diagram illustrates the layered structure of the belt layers in a tire as described in the document.

[0016] Figure 4 It means Figure 1 The image shows an enlarged view of the tire tread area as described in the document.

[0017] Figure 5 It means Figure 4 An enlarged view of one side of the fetal face as described in the document.

[0018] Figure 6 It means Figure 1 The document contains enlarged views of the tire's sidewall and bead portions.

[0019] Figure 7 It means Figure 6 An enlarged view of the side wall section as described in the document.

[0020] Figure 8 It means Figure 1 The diagram illustrates the layered structure of the tire's carcass and belt layers as described in the document.

[0021] Figure 9 It means Figure 1 The diagram illustrates the tire variation example 1 described in the document.

[0022] Figure 10 It means Figure 1 The illustration shows the tire variation example 2 recorded in the document.

[0023] Figure 11 It means Figure 1 The illustration shows the tire variation example 3 recorded in the document.

[0024] Figure 12 This is a graph showing the results of performance tests on tires according to embodiments of the present invention.

[0025] Figure 13 This is a graph showing the results of performance tests on tires according to embodiments of the present invention.

[0026] Figure 14 This is a graph showing the results of performance tests on tires according to embodiments of the present invention. Detailed Implementation

[0027] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to this embodiment. Furthermore, the constituent elements of this embodiment include elements that are replaceable while maintaining the identity of the invention, and the replacements are obvious. Moreover, the various variations described in this embodiment can be arbitrarily combined within the scope that is obvious to those skilled in the art.

[0028] [tire]

[0029] Figure 1 This is a cross-sectional view showing the radial direction of the tire 1 according to an embodiment of the present invention. The figure shows a cross-sectional view of a single-sided region of the radial direction of the tire 1 mounted on the rim 10. In this embodiment, a pneumatic radial tire for passenger cars will be described as an example of a tire.

[0030] In this diagram, the tire's radial section is defined as the section cut along a plane including the tire's axis of rotation (not shown). Furthermore, the tire's equatorial plane CL is defined as a plane passing through the midpoint of the tire's cross-sectional width as specified by JATMA and perpendicular to the tire's axis of rotation. Additionally, the tire width direction is defined as parallel to the tire's axis of rotation, and the tire radial direction is defined as perpendicular to the tire's axis of rotation. Point T represents the tire's contact patch, and point Ac represents the tire's maximum width position.

[0031] Tire 1 has a ring-shaped structure centered on the tire's axis of rotation, and includes a pair of bead cores 11, 11, a pair of sidewall cores 12, 12, a carcass layer 13, a belt layer 14, tread rubber 15, a pair of sidewall rubbers 16, 16, a pair of rim cushioning rubbers 17, 17, and an inner liner 18 (see Figure 1 ).

[0032] A pair of bead cores 11, 11 are formed by winding one or more bead wires made of steel in a loop and multiple times, and embedded in the bead portion to form the left and right bead portions. A pair of sidewall cores 12, 12 are respectively disposed on the radial outer periphery of the tire of the pair of bead cores 11, 11 to reinforce the bead portion.

[0033] The carcass layer 13 has a multi-layered structure formed by stacking two carcass ply layers 13A and 13B, and is arranged in a ring between the left and right bead cores 11 to form the tire skeleton. Furthermore, the two ends of the carcass layer 13 are rolled back and secured to the outside in the tire width direction, enclosing the bead core 11 and the sidewall core 12. Additionally, the carcass ply layers 13A and 13B of the carcass layer 13 are constructed by coating multiple carcass cords made of organic fiber materials (e.g., aramid, nylon, polyester, rayon, etc.) with coated rubber and then rolling them, and have a cord angle of 80 degrees or more and 100 degrees or less (defined as the angle of inclination of the length direction of the carcass cord relative to the tire circumference).

[0034] The belt layer 14 is formed by stacking multiple belt ply layers 141-144, and is arranged around the outer periphery of the carcass layer 13. Figure 1 In its composition, the belted fabric layers 141 to 144 consist of a pair of cross belts 141 and 142, a belt covering layer 143, a pair of belt edge covering layers 144 and 144, and an additional belt 145.

[0035] A pair of cross-belt bundles 141 and 142 are constructed by coating rubber-coated multiple bundle cords made of steel or organic fiber material and then rolling them, having cord angles θ41 and θ42 with an absolute value of 15 degrees or more and 55 degrees or less (see below). Figure 3 The angle of inclination of the belt cord length direction relative to the tire circumference is defined as follows. Furthermore, a pair of cross belts 141 and 142 have cord angles with different signs, causing the belt cord length directions to intersect and overlap (so-called cross-ply structure). Additionally, the pair of cross belts 141 and 142 are stacked on the radial outer side of the tire carcass layer 13.

[0036] The belt cover layer 143 and a pair of belt edge cover layers 144, 144 are constructed by coating belt cover cords made of steel or organic fiber material with coated rubber, and have cord angles θ43, θ44 with an absolute value of 0 [deg] or more and 10 [deg] or less (see below). Figure 3 Furthermore, the belt cover layer 143 and the belt edge cover layer 144 are, for example, strips made by coating one or more belt cover cords with coated rubber, which are formed by repeatedly and spirally winding the strip around the outer periphery of the cross belts 141 and 142 along the tire circumference. In addition, the belt cover layer 143 is configured to cover the entire area of ​​the cross belts 141 and 142, and a pair of belt edge cover layers 144 are configured to cover the left and right edges of the cross belts 141 and 142 starting from the radially outer side of the tire.

[0037] Additional belt 145 is, for example, (1) a third cross belt, which is constructed by coating multiple belt cords made of steel or organic fiber material with coated rubber and rolling, and has a cord angle θ45 of 15 [deg] or more and 80 [deg] or less in absolute value (see below). Figure 3 (2) So-called high-angle belts, which are made by coating multiple belt cords made of steel or organic fiber materials with coated rubber and rolling them, and have a cord angle θ45 of 45 degrees or more and 70 degrees or less, preferably 54 degrees or more and 68 degrees (see below) in absolute value. Figure 9 In addition, an additional belt 145 is disposed between (a) the inner diameter side cross belt 141 and the carcass ply 13 (see Figure 1 and the following Figure 3 (b) between a pair of crossbands 141 and 142 (illustration omitted), or (c) radially outside a pair of crossbands 141 and 142 (see below). Figure 9 In these configurations, the additional belt 145 suppresses the increase in tire outer diameter and improves the tire's load-bearing capacity.

[0038] The tread rubber 15 is disposed on the radial outer periphery of the tire carcass layer 13 and the belt layer 14 to form the tread portion of the tire 1. Furthermore, the tread rubber 15 has a crown tread 151 and a base tread 152.

[0039] The crown tread 151 is made of a rubber material with excellent ground contact characteristics and weather resistance, covering the entire tire contact area and protruding from the tread, thus forming the outer surface of the tread portion. Furthermore, the crown tread 151 has a rubber hardness Hs_cap of 50 or more and 80 or less, a modulus M_cap [MPa] at 100% elongation of 1.0 or more and 4.0 or less, and a loss tangent tanδ_cap of 0.03 or more and 0.36 or less, preferably having a rubber hardness Hs_cap of 58 or more and 76 or less, a modulus M_cap [MPa] at 100% elongation of 1.5 or more and 3.2 or less, and a loss tangent tanδ_cap of 0.06 or more and 0.29 or less.

[0040] The rubber hardness Hs was determined according to JIS K6253 at a temperature of 20°C.

[0041] Modulus (fracture strength) is determined according to JIS K6251 (using a No. 3 dumbbell) by a tensile test at 20 °C using a dumbbell-shaped specimen.

[0042] The loss tangent tanδ was measured using a viscoelastic spectrometer manufactured by Toyo Seiki Co., Ltd., under conditions of 60°C, 10% shear strain, ±0.5% amplitude, and 20 Hz frequency.

[0043] The base tread 152 is made of a heat-resistant rubber material and is sandwiched between the crown tread 151 and the belt layer 14, forming the base part of the tread rubber 15. Furthermore, the base tread 152 has a rubber hardness Hs_ut of 47 or more and 80 or less, a modulus M_ut [MPa] at 100% elongation of 1.4 or more and 5.5 or less, and a loss tangent tanδ_ut of 0.02 or more and 0.23 or less. Preferably, it has a rubber hardness Hs_cap of 50 or more and 65 or less, a modulus M_ut [MPa] at 100% elongation of 1.7 or more and 3.5 or less, and a loss tangent tanδ_ut of 0.03 or more and 0.10 or less.

[0044] Furthermore, the difference in rubber hardness, Hs_cap - Hs_ut, is in the range of 3 or more and 20 or less, preferably in the range of 5 or more and 15 or less. Additionally, the difference in modulus, M_cap - M_ut [MPa], is in the range of 0 or more and 1.4 or less, preferably in the range of 0.1 or more and 1.0 or less. Furthermore, the difference in loss tangent, tanδ_cap - tanδ_ut, is in the range of 0 or more and 0.22 or less, preferably in the range of 0.02 or more and 0.16 or less.

[0045] A pair of sidewall rubbers 16, 16 are respectively disposed on the outer side of the tire carcass layer 13 in the tire width direction to form the left and right sidewall portions. Figure 1 In this configuration, the radially outer end of the sidewall rubber 16 is positioned on the lower layer of the tread rubber 15 and sandwiched between the end of the belt layer 14 and the carcass layer 13. However, it is not limited to this; the radially outer end of the sidewall rubber 16 may also be positioned on the outer layer of the tread rubber 15 and exposed in the tire sidewall reinforcement (not shown). In this case, the belt layer separator rubber (not shown) is sandwiched between the end of the belt layer 14 and the carcass layer 13.

[0046] Furthermore, the sidewall rubber 16 has a rubber hardness Hs_sw of 48 or more and 65 or less, a modulus M_sw [MPa] of 100% elongation of 1.0 or more and 2.4 or less, and a loss tangent tanδ_sw of 0.02 or more and 0.22 or less. Preferably, it has a rubber hardness Hs_sw of 50 or more and 59 or less, a modulus M_sw [MPa] of 100% elongation of 1.2 or more and 2.2 or less, and a loss tangent tanδ_sw of 0.04 or more and 0.20 or less.

[0047] A pair of rim cushioning rubbers 17, 17 extend radially inward from the inner side of the tire's radial direction from the rolled-back portion of the left and right bead cores 11, 11 and the carcass layer 13, towards the outer side in the tire's width direction, forming the rim mating surface of the bead portion. Figure 1 In the configuration, the radially outer end of the tire of the rim buffer rubber 17 is inserted into the lower layer of the sidewall rubber 16, thereby being sandwiched and disposed between the sidewall rubber 16 and the carcass layer 13.

[0048] The inner liner 18 is an air-permeable layer disposed on the inner surface of the tire cavity and covering the carcass layer 13. It inhibits oxidation of the carcass layer 13 due to exposure and also prevents leakage of air filled in the tire. Furthermore, the inner liner 18 may be made of, for example, a rubber composition with butyl rubber as the main component, or a thermoplastic resin or a thermoplastic elastomer composition in which elastomer components are mixed.

[0049] In addition, Figure 1In this design, the tire outer diameter OD [mm] is in the range of 200 ≤ OD ≤ 660, preferably in the range of 250 [mm] ≤ OD ≤ 580 [mm]. By using this small-diameter tire, the improved load-bearing capacity described later can be significantly achieved. Furthermore, the total tire width SW [mm] is in the range of 100 ≤ SW ≤ 400, preferably in the range of 105 [mm] ≤ SW ≤ 340 [mm]. Using this small-diameter tire 1, for example, the floor of a small vehicle can be lowered to increase interior space. In addition, due to the small moment of inertia, the tire weight is also small, thus reducing fuel consumption and transportation costs. In particular, if this small-diameter tire is installed on the wheel hub motor of a vehicle, the load on the motor can be effectively reduced.

[0050] The tire outer diameter (OD) is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0051] The total width of a tire (SW) is measured as the straight-line distance between the sidewalls (including all parts such as patterns and lettering on the tire sidewalls) when the tire is mounted on a specified rim, with a specified internal pressure and in an unloaded state.

[0052] The specified rim refers to the "applicable rim" as specified by JATMA, the "design rim" as specified by TRA, or the "measuring rim" as specified by ETRTO. Furthermore, the specified internal pressure refers to the "maximum tire pressure" as specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" as specified by TRA, or the "inflation pressure" as specified by ETRTO. Additionally, the specified load refers to the "maximum load capacity" as specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" as specified by TRA, or the "load capacity" as specified by ETRTO. However, in JATMA, for passenger car tires, the specified internal pressure is 180 kPa, and the specified load is 88% of the maximum load capacity.

[0053] Furthermore, the total tire width SW [mm] relative to the tire outer diameter OD [mm] is in the range of 0.23≤SW / OD≤0.84, preferably in the range of 0.25≤SW / OD≤0.81.

[0054] Furthermore, the tire outer diameter OD and the total tire width SW preferably satisfy the following formula (1). Wherein, A1min=-0.0017, A2min=0.9, A3min=130, A1max=-0.0019, A2max=1.4, A3max=400, preferably A1min=-0.0018, A2min=0.9, A3min=160, A1max=-0.0024, A2max=1.6, A3max=362.

[0055] [Formula 1]

[0056]

[0057] If the tire 1 described above is used, it is envisioned to use a rim 10 with a rim diameter of 5 inches or more and 16 inches or less (i.e., 125 mm or more and 407 mm or less). Furthermore, the rim diameter RD (mm) relative to the tire outer diameter OD (mm) is in the range of 0.50 ≤ RD / OD ≤ 0.74, preferably in the range of 0.52 ≤ RD / OD ≤ 0.71. This lower limit ensures the rim diameter RD, and in particular, ensures the space for the hub motor. This lower limit also ensures the tire volume V, as described later, and ensures the tire's load capacity.

[0058] It should be noted that the inner diameter of the tire is equal to the rim diameter RD of the rim 10.

[0059] Furthermore, it is envisioned that the aforementioned tire 1 will be used at an internal pressure higher than the specified internal pressure, specifically, between 350 kPa and 1200 kPa, preferably between 500 kPa and 1000 kPa. The lower limit effectively reduces the rolling resistance of the tire, while the upper limit ensures the safety of the internal pressure filling operation.

[0060] Furthermore, it is envisioned that the aforementioned tire 1 is installed on a low-speed vehicle, such as a minibus. The maximum speed of the vehicle is 100 km / h or less, preferably 80 km / h or less, and more preferably 60 km / h or less. It is also envisioned that the aforementioned tire 1 is installed on a vehicle with 6 to 12 wheels. This allows for appropriate utilization of the tire's load-bearing capacity.

[0061] Additionally, the tire's aspect ratio, i.e., the tire section height SH [mm] (see below) Figure 2 ) and tire section width [mm] (dimension markings omitted in the figure: in Figure 1 The ratio of the width of the tire to the total width of the tire (SW) is in the range of 0.16 or higher and 0.85 or lower, preferably in the range of 0.19 or higher and 0.82 or lower.

[0062] The tire section height SH is the distance of half the difference between the tire's outer diameter and the rim diameter. It is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0063] The tire section width is measured as the straight distance between the sidewalls (excluding patterns, characters, etc. on the tire sidewalls) when the tire is mounted on a specified rim, given a specified internal pressure, and is in an unloaded state.

[0064] Furthermore, the tire contact width TW relative to the total tire width SW is in the range of 0.65≤TW / SW≤0.95, preferably in the range of 0.80≤TW / SW≤0.92.

[0065] Tire contact width (TW) is measured as the maximum straight-line distance in the axial direction of the tire on the contact surface between the tire and the flat plate when the tire is mounted on a specified rim and subjected to a specified internal pressure, placed perpendicular to a flat plate in a stationary state, and subjected to a load corresponding to a specified load.

[0066] Furthermore, the tire volume V [m^3] relative to the tire outer diameter OD [mm] is preferably within the range of 4.0 ≤ (V / OD) × 10^6 ≤ 60, and more preferably within the range of 6.0 ≤ (V / OD) × 10^6 ≤ 50. This optimizes the tire volume V. Specifically, by using the aforementioned lower limit, the tire volume can be ensured, thereby ensuring the tire's load-bearing capacity. Especially for small-diameter tires, their use under high internal pressure and high load is foreseeable; therefore, it is preferable to sufficiently ensure the tire volume V. By using the aforementioned upper limit, tire enlargement caused by excessively large tire volume V can be suppressed.

[0067] Furthermore, the tire volume V[m^3] relative to the rim diameter RD[mm] is in the range of 0.5≤V×RD≤17, preferably in the range of 1.0≤V×RD≤15.

[0068] [Bead core]

[0069] exist Figure 1 As described above, the pair of bead cores 11, 11 are formed by winding one or more bead wires (not shown) made of steel in a loop and multiple loops. In addition, a pair of sidewall cores 12, 12 are respectively disposed on the radial outer periphery of the tire of the pair of bead cores 11, 11.

[0070] Furthermore, the breaking strength Tbd[N] of a bead core 11 relative to the tire outer diameter OD[mm] is in the range of 45≤Tbd / OD≤120, preferably in the range of 50≤Tbd / OD≤110, and more preferably in the range of 60≤Tbd / OD≤105. In addition, the breaking strength Tbd[N] of the bead core relative to the total tire width SW[mm] is in the range of 90≤Tbd / SW≤400, preferably in the range of 110≤Tbd / SW≤350. This ensures adequate load-bearing capacity of the bead core 11. Specifically, by using the above lower limits, tire deformation under high loads can be suppressed, thereby ensuring tire wear resistance. Furthermore, it allows for use under high internal pressure, reducing tire rolling resistance. Especially for small-diameter tires, their use under high internal pressure and high loads is foreseeable, thus significantly achieving the aforementioned tire wear resistance and rolling resistance reduction effects. The aforementioned upper limit can suppress the decrease in rolling resistance caused by the increase in the mass of the bead core.

[0071] The breaking strength Tbd [N] of the bead core 11 is calculated as the product of the breaking strength [N / bead] of each bead wire and the total number of bead wires in the radial sectional view. The breaking strength of the bead wire is determined according to JIS G 3510 by a tensile test at 20 [°C].

[0072] Furthermore, the breaking strength Tbd [N] of the bead core 11, relative to the tire outer diameter OD [mm], the distance SWD [mm], and the rim diameter RD [mm], preferably satisfies the following formula (2). Wherein, B1min=0.26, B2min=10.0, B1max=2.5, B2max=99.0, preferably B1min=0.35, B2min=14.0, B1max=2.5, B2max=99.0, more preferably B1min=0.44, B2min=17.6, B1max=2.5, B2max=99.0, and even more preferably B1min=0.49, B2min=17.9, B1max=2.5, B2max=99.0. Further, it is preferable to use the specified tire internal pressure P [kPa], with B1min=0.0016×P and B2min=0.07×P.

[0073] [Formula 2]

[0074]

[0075] The distance SWD is twice the radial distance from the tire's rotation axis (illustration omitted) to the tire's maximum width position Ac, which is the diameter of the tire's maximum width position Ac. It is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0076] The maximum tire width position Ac is defined as the maximum width position of the tire section width as specified by JATMA.

[0077] Furthermore, in a radial cross-sectional view of a bead core 11, the total cross-sectional area σbd [mm²] of the bead wires made of steel is in the range of 0.025 ≤ σbd / OD ≤ 0.075 relative to the tire outer diameter OD [mm], preferably in the range of 0.030 ≤ σbd / OD ≤ 0.065. In addition, the total cross-sectional area σbd [mm²] of the bead wires is in the range of 11 ≤ σbd ≤ 36, preferably in the range of 13 ≤ σbd ≤ 33. Thus, the breaking strength Tbd [N] of the bead core 11 can be achieved.

[0078] The total cross-sectional area σbd[mm^2] of the bead wire is calculated as the sum of the cross-sectional areas of the bead wires in the radial sectional view of each bead core 11.

[0079] For example, in Figure 1 In its configuration, the bead core 11 has a quadrilateral formed by bead wires with circular cross-sections arranged in a grid pattern (illustration omitted). However, it is not limited to this; the bead core 11 may also have a hexagon formed by bead wires with circular cross-sections arranged in a densest filling structure (illustration omitted). Furthermore, any arrangement of bead wires may be used to the extent that will be obvious to those skilled in the art.

[0080] Furthermore, the total cross-sectional area σbd[mm^2] of the bead wires is preferably satisfied by the following formula (3) relative to the tire outer diameter OD[mm], the distance SWD[mm], and the rim diameter RD[mm]. Wherein, Cmin=30, Cmax=8, preferably Cmin=25, Cmax=10.

[0081] [Formula 3]

[0082]

[0083] Furthermore, the total cross-sectional area σbd [mm^2] of the bead wires relative to the total number of cross-sections (i.e., the total number of turns) Nbd [wires] of the bead wires of one bead core 11 in the radial sectional view is in the range of 0.50 ≤ σbd / Nbd ≤ 1.40, preferably in the range of 0.60 ≤ σbd / Nbd ≤ 1.20. That is, the cross-sectional area σbd' [mm^2] of a single bead wire is in the range of 0.50 [mm^2 / wire] or more and 1.40 [mm^2 / wire] or less, preferably in the range of 0.60 [mm^2 / wire] or more and 1.20 [mm^2 / wire] or less.

[0084] In addition, the maximum width Wbd [mm] of a bead core 11 in a radial sectional view (see below) Figure 2 The total cross-sectional area σbd [mm^2] of the bead wire is in the range of 0.16≤Wbd / σbd≤0.50, preferably in the range of 0.20≤Wbd / σbd≤0.40.

[0085] In addition, Figure 1 In this configuration, the distance Dbd [mm] between the centers of gravity of a pair of bead cores 11, 11 is within the range of 0.63 ≤ Dbd / SW ≤ 0.97 relative to the total tire width SW [mm], preferably within the range of 0.65 ≤ Dbd / SW ≤ 0.95. By using the lower limit mentioned above, tire deflection can be reduced, thus lowering rolling resistance. By using the upper limit mentioned above, stress acting on the tire sidewall can be reduced, thus suppressing tire failure.

[0086] [Peripheral layer]

[0087] Figure 2 It means Figure 1 An enlarged view of tire 1 as described in the figure. This figure shows a unilateral region bounded by the tire's equatorial plane CL.

[0088] exist Figure 1 As described above, the carcass layer 13 is composed of two stacked carcass ply layers 13A and 13B, arranged in a ring between the left and right bead cores 11. Furthermore, the two ends of the carcass layer 13 are rolled back and secured to the outside in the tire width direction in a manner that wraps around the bead core 11 and the sidewall core 12.

[0089] Furthermore, the breaking strength Tcs [N / 50mm] of each 50mm width of the carcass plies 13A and 13B constituting the carcass ply 13, relative to the tire outer diameter OD [mm], is in the range of 17 ≤ Tcs / OD ≤ 120, preferably in the range of 20 ≤ Tcs / OD ≤ 60. Furthermore, the breaking strength Tcs [N / 50mm] of the carcass ply 13, relative to the total tire width SW [mm], is in the range of 30 ≤ Tcs / SW ≤ 260, preferably in the range of 35 ≤ Tcs / SW ≤ 180. This ensures adequate load-bearing capacity of the carcass ply 13. Specifically, by meeting the above lower limits, tire deformation under high loads can be suppressed, thereby ensuring tire wear resistance. Furthermore, it allows for use under high internal pressure, reducing tire rolling resistance. Especially for small-diameter tires, their use under high internal pressure and high loads is foreseeable, thus significantly achieving the aforementioned tire wear resistance and rolling resistance reduction effects. By using the aforementioned upper limit, the decrease in rolling resistance caused by the increase in the mass of the carcass layer can be suppressed.

[0090] The breaking strength Tcs [N / 50mm] of the carcass ply is calculated as follows. Specifically, the carcass ply 13A and 13B, which are mounted on the left and right bead cores 11 and extend throughout the entire inner circumference of the tire, are defined as the effective carcass ply. Furthermore, the breaking strength [N / ply] of each carcass cord constituting the effective carcass ply 13A and 13B is calculated as the product of the density of the carcass cords per 50mm width on the tire's equatorial plane CL and the density of the cords per 50mm width, and this product is taken as the breaking strength Tcs [N / 50mm] of the carcass ply. The breaking strength of the carcass cord is determined according to JIS L1017 by a tensile test at 20°C. For example, if a carcass cord is formed by twisting multiple monofilaments together, the breaking strength of the twisted carcass cord is measured, and the breaking strength Tcs of the carcass ply 13 is calculated. Additionally, as... Figure 1 As shown, if the carcass layer 13 is a multi-layer structure formed by stacking multiple effective carcass plies 13A and 13B, then the above-mentioned breaking strength Tcs is defined for each of the multiple effective carcass plies 13A and 13B.

[0091] For example, in Figure 1In its configuration, the carcass layer 13 has a multi-layer structure consisting of two carcass ply layers 13A and 13B. Furthermore, the carcass ply layers 13A and 13B are composed of carcass cords made of organic fiber materials (e.g., aramid, nylon, polyester, rayon, etc.) coated with rubber (illustration omitted). At this time, by having the carcass cords made of the aforementioned organic fiber materials have a cord diameter φcs [mm] in the range of 0.6 ≤ φcs ≤ 0.9 and a density Ecs [roots / 50mm] in the range of 40 ≤ Ecs ≤ 70, the breaking strength Tcs [N / 50mm] of the aforementioned carcass layer 13 is achieved. Furthermore, carcass cords made of various organic fiber materials, such as twisted nylon and aramid, can be used within a range that is readily apparent to those skilled in the art.

[0092] Furthermore, the total breaking strength TTcs [N / 50mm] of the carcass layer 13 relative to the tire outer diameter OD [mm] is preferably in the range of 400 ≤ TTcs / OD ≤ 1000 within the range of 300 ≤ TTcs / OD ≤ 1900. This ensures the overall load-bearing capacity of the carcass layer 13.

[0093] The total breaking strength TTcs [N / 50mm] of the carcass layer 13 is calculated as the sum of the breaking strengths Tcs [N / 50mm] of the effective carcass ply layers. Therefore, the total breaking strength TTcs [N / 50mm] of the carcass layer 13 increases with the increase of the breaking strength Tcs [N / 50mm] of each carcass ply, the number of carcass ply layers, the circumference of the carcass ply, etc.

[0094] Furthermore, the total breaking strength TTcs [N / 50mm] of the carcass layer 13, relative to the tire outer diameter OD [mm] and distance SWD [mm], preferably satisfies the following formula (4). Wherein, Dmin=2.2, Dmax=40, preferably Dmin=4.3, Dmax=40, more preferably Dmin=6.5, Dmax=40, and even more preferably Dmin=8.7, Dmax=40. Further, it is preferable to use the specified tire internal pressure P [kPa], where Dmin=0.02×P.

[0095] [Formula 4]

[0096]

[0097] In addition, Figure 1 In its composition, such as Figure 2 As shown, the carcass layer 13 has a main body portion 131 extending along the inner surface of the tire and an up-wound portion 132 that is rolled up to the outer side in the tire width direction and extends radially along the tire, in a manner that encloses the bead core 11. Furthermore, in Figure 2In this case, the radial height Hcs [mm] from the measurement point of the rim diameter RD to the end of the up-rolled portion 132 of the carcass layer 13 with respect to the tire cross-sectional height SH [mm] is within the range of 0.49 ≤ Hcs / SH ≤ 0.80, preferably within the range of 0.55 ≤ Hcs / SH ≤ 0.75. Thereby, the radial height Hcs of the up-rolled portion 132 of the carcass layer 13 can be optimized. Specifically, by the above lower limit, the load capacity of the sidewall portion can be ensured, and by the above upper limit, the reduction of the rolling resistance caused by the increase in the mass of the carcass layer can be suppressed.

[0098] The radial height Hcs [mm] of the up-rolled portion 132 of the carcass layer 13 is measured in the state of being mounted on a specified rim and filled with a specified internal pressure while being unloaded. In addition, as Figure 2 shown, if the carcass layer 13 is formed of two carcass ply layers 13A and 13B, a larger radial height Hcs [mm] is adopted.

[0099] For example, in Figure 2 the structure, both of the two carcass ply layers 13A and 13B are up-rolled to the outside in the tire width direction so as to wrap the bead core 11. In addition, the up-rolled portion 132 of the inner-diameter-side carcass ply layer 13A covers the radially outer end (omitted in the figure) of the up-rolled portion 132 of the outer-diameter-side carcass ply layer 13B from the outside in the tire width direction. In addition, the radially outer end (omitted in the figure) of the up-rolled portion 132 of the inner-diameter-side carcass ply layer 13A is located in the region between the tire maximum width position Ac and the end of the belt layer 14 (point Au described later), and more specifically, is located in the region at the radially position Au' which is 70 [%] of the distance Hu described later from the tire maximum width position Ac. At this time, the contact height Hcs' [mm] of the main body portion 131 of the carcass layer 13 with respect to the up-rolled portion 132 is within the range of 0.07 ≤ Hcs' / SH, preferably within the range of 0.15 ≤ Hcs' / SH. Thereby, the load capacity of the sidewall portion can be effectively improved. The upper limit of the ratio Hcs' / SH is not particularly limited, but is restricted by the relationship that the contact height Hcs' has Hcs' < Hcs with respect to the radial height Hcs of the up-rolled portion 132 of the carcass layer 13.

[0100] The contact height Hcs' of the carcass layer 13 is the extension length in the tire radial direction of the region where the main body portion 131 and the up-rolled portion 132 contact each other, and is measured in the state of being mounted on a specified rim and filled with a specified internal pressure while being unloaded.

[0101] It should be noted that the end of the upper rolled portion 132 of the carcass layer 13 is not limited to the above configuration. By giving the carcass layer 13 a so-called low fold structure, it can also be configured in the area between the tire's maximum width position Ac and the bead core (illustration omitted).

[0102] [Belt layer]

[0103] Figure 3 It means Figure 1 The diagram illustrates the layered structure of the belt layers of the tire 1 described herein. In this diagram, fine lines attached to each belt ply 141-145 schematically show the arrangement of the belt cords.

[0104] exist Figure 1 In its configuration, as described above, the belt layer 14 is formed by stacking multiple layers of belt fabric layers 141 to 145. Furthermore, as... Figure 3 The belted fabric layers 141-145 are composed of a pair of cross belts 141, 142, a belt cover layer 143, a pair of belt edge cover layers 144, 144 and an additional belt 145.

[0105] At this point, the breaking strength Tbt [N / 50mm] of each 50mm width of the pair of cross belts 141, 142 and the additional belt 145, relative to the tire outer diameter OD [mm], is in the range of 25 ≤ Tbt / OD ≤ 250, preferably in the range of 30 ≤ Tbt / OD ≤ 180. Furthermore, the breaking strength Tbt [N / 50mm] of the cross belts 141, 142 and the additional belt 145, relative to the total tire width SW [mm], is in the range of 45 ≤ Tbt / SW ≤ 500, preferably in the range of 50 ≤ Tbt / SW ≤ 300. This ensures that the load-bearing capacity of each pair of cross belts 141, 142 and the additional belt 145 is adequately guaranteed. Specifically, by using the above lower limits, tire deformation under high loads can be suppressed, thereby ensuring the tire's wear resistance. Furthermore, it allows for use under high internal pressure, reducing tire rolling resistance. Especially for small-diameter tires, their use under high internal pressure and high load is foreseeable, thus significantly achieving the aforementioned tire wear resistance and rolling resistance reduction effects. The aforementioned upper limit can suppress the reduction in rolling resistance caused by the increase in the mass of the belt ply.

[0106] The breaking strength Tbt [N / 50mm] of the belt cord layer is calculated as follows. Specifically, the belt cord layer extending across 80% of the tire contact patch width TW centered on the tire equator CL (i.e., the central portion of the tire contact patch area) is defined as the effective belt cord layer. Furthermore, the breaking strength [N / cord] of each belt cord constituting the effective belt cord layer is calculated as the product of the density of belt cords per 50mm width within the aforementioned 80% region of the tire contact patch width TW, and this product is taken as the breaking strength Tbt [N / 50mm] of the belt cord layer. The breaking strength of the belt cord is determined according to JIS L1017 by a tensile test at 20°C. For example, if a belt cord is formed by twisting multiple monofilaments together, the breaking strength of the twisted belt cord is measured, thereby calculating the breaking strength Tbt of the belt cord layer. Additionally, if the belt layer 14 is a configuration formed by stacking multiple layers of effective belt fabric (see...), Figure 1 Then, the above-mentioned breaking strength Tbt is defined for each layer in the multi-layer effective belted fabric. For example, in Figure 1 In the configuration, a pair of cross belts 141, 142, a belt cover layer 143, and an additional belt 145 are equivalent to an effective belt fabric layer.

[0107] For example, in Figure 3 In the configuration, a pair of cross belts 141, 142 and an additional belt 145 are constructed by arranging steel belt cords coated with rubber at cord angles θ41, θ42, θ45 relative to the tire circumference of 15 [deg] or more and 80 [deg] or less. Furthermore, by having the aforementioned steel belt cords have a cord diameter φbt [mm] in the range of 0.50≤φbt≤1.80 and a density Ebt [roots / 50mm] in the range of 15≤Ebt≤60, the breaking strength Tbt [N / 50mm] of the aforementioned cross belts 141, 142 and additional belt 145 is achieved. Furthermore, the cord diameter φbt [mm] and density Ebt [strands / 50mm] are preferably in the ranges of 0.55 ≤ φbt ≤ 1.60 and 17 ≤ Ebt ≤ 50, more preferably in the ranges of 0.60 ≤ φbt ≤ 1.30 and 20 ≤ Ebt ≤ 40. Additionally, the belt cord is formed by twisting multiple monofilaments together, and its monofilament diameter φbts [mm] is in the range of 0.16 ≤ φbts ≤ 0.43, preferably in the range of 0.21 ≤ φbts ≤ 0.39.

[0108] Furthermore, the cross-belt bundles 141, 142 and the additional belt bundle 145 are not limited to the above-described configuration, and may also be composed of belt cords made of organic fiber materials (e.g., aramid, nylon, polyester, rayon, etc.) coated with rubber. In this case, by having the belt cords made of the aforementioned organic fiber materials have a cord diameter φbt [mm] in the range of 0.50 ≤ φbt ≤ 0.90 and a density Ebt [roots / 50mm] in the range of 30 ≤ Ebt ≤ 65, the breaking strength Tbt [N / 50mm] of the aforementioned cross-belt bundles 141, 142 and the additional belt bundle 145 is achieved. In addition, belt cords made of various organic fiber materials such as twisted nylon and aramid can be used within a range that is obvious to those skilled in the art.

[0109] Furthermore, the total breaking strength TTbt [N / 50mm] of the belt layer 14 relative to the tire outer diameter OD [mm] is preferably in the range of 70 ≤ TTbt / OD ≤ 750, more preferably in the range of 110 ≤ TTbt / OD ≤ 690, more preferably in the range of 150 ≤ TTbt / OD ≤ 600, and even more preferably in the range of 170 ≤ TTbt / OD ≤ 560. This ensures the overall load-bearing capacity of the belt layer 14. Further, it is preferable to use the specified tire internal pressure P [kPa], where 0.16 × P ≤ TTbt / OD.

[0110] The total breaking strength TTbt [N / 50mm] of the belt layer 14 is based on the above effective belt fabric layer (in Figure 1 The tensile strength Tbt [N / 50mm] of the belt layer 14 is calculated as the sum of the tensile strengths of a pair of cross belts 141, 142, belt cover layer 143, and additional belt 145. Therefore, the total tensile strength TTbt [N / 50mm] of the belt layer 14 increases with the increase of the tensile strength Tbt [N / 50mm] of each belt fabric layer, the number of layers of the belt fabric layer, etc.

[0111] In addition, Figure 3 In the middle, the narrowest belt ply layer among a pair of cross-belt layers 141, 142 and additional belt 145 (in Figure 3 In this context, the breaking strength Tbt_min [N / 50mm] of the outer diameter side cross belt 142) relative to the total breaking strength TTbt [N / 50mm] of the belt layer 14 is within the range of 0.10 ≤ Tbt_min / TTbt ≤ 0.40, preferably within the range of 0.12 ≤ Tbt_min / TTbt ≤ 0.35. The lower limit ensures the tire outer diameter increase suppression effect of the additional belt 145, while the upper limit ensures the belt durability improvement effect of other belt ply layers.

[0112] In addition, Figure 3In the middle, the width Wbmax [mm] of the widest belt ply among a pair of cross belts 141, 142 and an additional belt 145 (in Figure 3 In the middle, the width Wb1 [mm] of the cross belt 141 on the inner diameter side or the width Wb5 [mm] of the additional belt 145 is relative to the width Wbmin [mm] of the narrowest belt fabric layer (in Figure 3 In the case of the cross-belt bundle 142 on the outer diameter side, the width Wb2 [mm] is in the range of 1.00 ≤ Wbmax / Wbmin ≤ 1.40, preferably in the range of 1.10 ≤ Wbmax / Wbmin ≤ 1.35. Furthermore, the width Wbmax [mm] of the widest bundle fabric layer is relative to the width Wbmid [mm] of the second widest bundle fabric layer (in... Figure 3 In the case of additional belt 145, the width Wb5 [mm] or the width Wb1 [mm] of the cross belt 141 on the inner diameter side is within the range of 1.00 ≤ Wbmax / Wbmid ≤ 1.30. Furthermore, the width Wbmin [mm] of the narrowest belt fabric layer (in...) Figure 3 In this context, the width Wb2 [mm] of the cross belt 142 on the outer diameter side, relative to the total tire width SW [mm], is within the range of 0.61 ≤ Wbmin / SW ≤ 0.96, preferably within the range of 0.70 ≤ Wbmin / SW ≤ 0.94. This has the advantage of optimizing the relationship between the widths Wb1, Wb2, and Wb5 of the belt ply layers 141, 142, and 145. Specifically, by using the aforementioned lower limit, the width of the belt ply layer can be ensured, optimizing the distribution of ground pressure in the tire's contact patch area, thereby ensuring the tire's resistance to uneven wear. By using the aforementioned upper limit, deformation of the belt ply layer ends during tire rolling can be reduced, suppressing the separation of the peripheral rubber at the ends of the belt ply layer.

[0113] The width of the belt ply is the distance between the left and right ends of each belt ply in the direction of the tire's rotation axis, and is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0114] Furthermore, the width Wbmax [mm] of the widest belt ply, relative to the width Wbmin [mm] of the narrowest belt ply and the total tire width SW [mm], preferably satisfies the following formula (5). Wherein, Umin=10, Umax=30, preferably Umin=11, Umax=28.

[0115] [Formula 5]

[0116]

[0117] Furthermore, the width Wbmax [mm] of the widest belt ply, relative to the width Wbmid [mm] of the second widest belt ply, and the total tire width SW [mm] preferably satisfy the following formula (6). Wherein, Vmin=10.0, Vmax=26.0, preferably Vmin=10.5, Umax=25.0, more preferably Vmin=10.5, Umax=24.0.

[0118] [Formula 6]

[0119]

[0120] In addition, the width Wbmax [mm] of the widest belt ply among the pair of cross belts 141, 142 and the additional belt 145 (in Figure 3 In the above, the width Wb1 [mm] of the cross belt 141 on the inner diameter side or the width Wb5 [mm] of the additional belt 145 is in the range of 0.85 ≤ Wbmax / TW ≤ 1.23 relative to the tire contact width TW [mm], preferably in the range of 0.90 ≤ Wbmax / TW ≤ 1.20.

[0121] For example, in Figures 1-3 In this configuration, a wide cross belt 141 is disposed at the innermost radial layer of the tire, and a narrow cross belt 142 is disposed at the radial outer edge of the wide cross belt 141. Furthermore, an additional belt 145 is a third cross belt with a cord angle of 15 degrees or more and 80 degrees or less, disposed at the radial outer edge of the narrow cross belt 142 and having a cord angle of a different sign than that of the narrow cross belt 142. Additionally, a belt cover layer 143 is disposed at the radial outer edge of the additional belt 145, covering the entire pair of cross belts 141, 142 and the additional belt 145. Furthermore, a pair of belt edge cover layers 144, 144 are spaced apart from each other and disposed at the radial outer edge of the belt cover layer 143, respectively covering the left and right edges of the pair of cross belts 141, 142 and the additional belt 145.

[0122] [Tread profile and tread thickness]

[0123] Figure 4 It means Figure 1 An enlarged view of the tread of tire 1 as described.

[0124] exist Figure 4In this design, the tread profile drop DA [mm] at the tire contact patch T, the tire contact width TW [mm], and the tire outer diameter OD [mm] have a relationship of 0.015 ≤ TW / (DA×OD) ≤ 0.400, preferably 0.020 ≤ TW / (DA×OD) ≤ 0.250. Furthermore, the tread profile drop DA [mm] at the tire contact patch T has a relationship of 0.008 ≤ DA / TW ≤ 0.090 relative to the tire contact width TW [mm], preferably 0.013 ≤ DA / TW ≤ 0.080. This optimizes the drop angle of the tread and shoulder areas (defined by the ratio DA / (TW / 2)) and appropriately ensures the load-bearing capacity of the tread. Specifically, by using the aforementioned lower limits, the drop angle of the tread and shoulder areas can be ensured, thereby suppressing the reduction in wear life caused by excessive contact pressure in the tread and shoulder areas. By achieving the aforementioned upper limit, the tire contact patch becomes flatter, resulting in more uniform contact pressure and ensuring the tire's wear resistance. This is especially beneficial for small-diameter tires, which are designed for use under high internal pressure and heavy loads; therefore, the aforementioned configuration effectively optimizes the contact pressure distribution in the tire contact patch area. Furthermore, by enhancing the carcass breaking strength Tcs of the carcass layer 13 and the belt breaking strength Tbt of the belt layer 14 as described above, excessive contact pressure can be prevented. On the other hand, by giving the tire a rounded shoulder, heat generated in the tread area during tire rolling can be suppressed, improving tire durability and reducing the rubber volume in the tread area, thus improving the tire's low rolling resistance performance.

[0125] The drop DA is the radial distance from the intersection point C1 of the tire equatorial plane CL and the tread profile in the tire radial cross-sectional view along the tire's radial direction to the tire contact patch T. It is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0126] The tire profile is the outline of the tire in a cross-sectional view along the tire's radial direction, measured using a laser profile measuring instrument. For example, a tire profile measuring device (manufactured by Matsuo Co., Ltd.) can be used as the laser profile measuring instrument.

[0127] Furthermore, the difference in tread profile DA [mm] at the tire contact point T is preferably satisfied by the following formula (7) relative to the tire outer diameter OD [mm] and the total tire width SW [mm]. Wherein, Emin=3.5, Emax=17, preferably Emin=3.8, Emax=13, and even more preferably Emin=4.0, Emax=9.

[0128] [Formula 7]

[0129]

[0130] also, Figure 4 The code defines a point C1 on the tread profile in the tire equatorial plane CL and a pair of points C2 and C2 on the tread profile at a distance of 1 / 4 of the tire ground contact width TW from the tire equatorial plane CL.

[0131] At this point, the radius of curvature TRc [mm] of the arc passing through point C1 and a pair of points C2 is in the range of 0.15 ≤ TRc / OD ≤ 12 relative to the tire outer diameter OD [mm], preferably in the range of 0.18 ≤ TRc / OD ≤ 8.0. Furthermore, the radius of curvature TRc [mm] of the arc is in the range of 30 ≤ TRc ≤ 3000, preferably in the range of 50 ≤ TRc ≤ 2300, and even more preferably in the range of 80 ≤ TRc ≤ 2000. This ensures adequate load-bearing capacity of the tread. Specifically, by using the lower limit mentioned above, the central area of ​​the tread becomes flat, making the ground pressure in the tire contact area more uniform, thereby ensuring the tire's wear resistance. By using the upper limit mentioned above, the reduction in wear life due to excessive ground pressure in the tread and shoulder areas can be suppressed. Especially for small-diameter tires, their use under high internal pressure and high load can be anticipated, thus effectively achieving the homogenization of ground pressure under these operating conditions.

[0132] The radius of curvature of the arc is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0133] In addition, Figure 4 In this configuration, the radius of curvature TRw [mm] of the arc passing through point C1 on the tire equatorial plane CL and the left and right tire contact points T and T' is within the range of 0.20 ≤ TRw / OD ≤ 10 relative to the tire outer diameter OD [mm], preferably within the range of 0.35 ≤ TRw / OD ≤ 8. Furthermore, the radius of curvature TRw [mm] of the arc is within the range of 100 ≤ TRw ≤ 2300, preferably within the range of 150 ≤ TRw ≤ 2000. This ensures adequate load-bearing capacity of the tread area. Specifically, by using the lower limit mentioned above, the entire tire contact area becomes flat, making the contact pressure uniform, thereby ensuring the tire's wear resistance. By using the upper limit mentioned above, the reduction in wear life due to excessive contact pressure in the tread and shoulder areas can be suppressed. Especially for small-diameter tires, their use under high internal pressure and high load can be anticipated, thus the above configuration effectively optimizes the contact pressure distribution in the tire contact area.

[0134] Furthermore, the radius of curvature TRw [mm] of the first arc passing through points C1 and C2 is within the range of 0.55 ≤ TRw / TRc ≤ 1.00, preferably within the range of 0.65 ≤ TRw / TRc ≤ 0.98, and more preferably within the range of 0.75 ≤ TRw / TRc ≤ 0.96, relative to the radius of curvature TRw [mm] of the second arc passing through point C1 and the tire contact patch T. This optimizes the tire's contact patch shape. Specifically, the lower limit disperses the contact patch pressure in the central area of ​​the tread, thereby improving tire wear life. The upper limit suppresses the reduction in wear life caused by excessive contact patch pressure in the tread and shoulder areas.

[0135] also, Figure 4 The definition includes point B1 on the tire carcass layer 13 on the tire equatorial plane CL, and points B1 extending from the left and right tire contact points T and T1 down to the outermost layer of the carcass layer 13 (in... Figure 4 In the middle, the feet of the perpendicular lines of the carcass ply 13B on the outer diameter side are B2 and B2.

[0136] At this point, the radius of curvature CRw of the arc passing through point B1 and the pair of points B2, B2, relative to the radius of curvature TRw of the arc passing through point C1 and the tire contact points T, T, is in the range of 0.35 ≤ CRw / TRw ≤ 1.45, preferably in the range of 0.40 ≤ CRw / TRw ≤ 1.40, and more preferably in the range of 0.45 ≤ CRw / TRw ≤ 1.35. Furthermore, the radius of curvature CRw [mm] is in the range of 100 ≤ CRw ≤ 2500, preferably in the range of 120 ≤ CRw ≤ 2200. This allows for a more optimized tire contact shape. Specifically, the lower limit mentioned above can suppress the reduction in wear life caused by the increase in rubber thickness in the tread and shoulder areas. The upper limit mentioned above can ensure the wear life of the central area of ​​the tread.

[0137] Figure 5 It means Figure 4 An enlarged view of one side of the fetal face as described in the document.

[0138] exist Figure 1 As described above, in the configuration, the belt layer 14 has a pair of cross belts 141, 142 and an additional belt 145, and the tread rubber 15 has a crown tread 151 and a base tread 152.

[0139] In addition, Figure 5In this design, the distance Tce [mm] from the tread profile on the tire equatorial surface CL to the outer periphery of the wide cross belt 141 has a relationship of 0.008 ≤ Tce / OD ≤ 0.13 relative to the tire outer diameter OD [mm], preferably 0.012 ≤ Tce / OD ≤ 0.10, and more preferably 0.015 ≤ Tce / OD ≤ 0.07. Furthermore, the distance Tce [mm] is within the range of 5 ≤ Tce ≤ 25, preferably within the range of 7 ≤ Tce ≤ 20. This ensures adequate load-bearing capacity of the tread. Specifically, the lower limit suppresses tire deformation under high loads, thus ensuring tire wear resistance. Especially for small-diameter tires, high internal pressure and high load use are foreseeable, resulting in significantly improved wear resistance. The upper limit suppresses the decrease in rolling resistance caused by increased tread rubber mass.

[0140] The distance Tce is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0141] The outer peripheral surface of the belted cord fabric layer is defined as the entire radially outer peripheral surface of the belted cord fabric layer, which is composed of belted cords and coated rubber.

[0142] Furthermore, the distance Tce [mm] from the tread profile on the tire equatorial surface CL to the outer periphery of the wide cross belt 141 is preferably satisfied by the following formula (8) relative to the tire outer diameter OD [mm]. Wherein, Fmin=35, Fmax=207, preferably Fmin=42, Fmax=202.

[0143] [Formula 8]

[0144]

[0145] Furthermore, the distance Tsh [mm] from the tread profile at the tire contact point T to the outer periphery of the wide cross belt 141, relative to the distance Tce [mm] on the tire equatorial plane CL, is preferably within the range of 0.60 ≤ Tsh / Tce ≤ 1.70, more preferably within the range of 0.85 ≤ Tsh / Tce ≤ 1.55, and even more preferably within the range of 0.97 ≤ Tsh / Tce ≤ 1.50. This lower limit ensures sufficient tread thickness in the shoulder area, thus suppressing repeated tire deformation during rolling and ensuring tire wear resistance. Furthermore, the upper limit ensures sufficient tread thickness in the central area, thus suppressing tire deformation under the characteristic high load conditions of small-diameter tires and ensuring tire wear resistance.

[0146] The distance Tsh is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure. Furthermore, when there is no wide crossbelt directly below the tire's contact patch T, the distance Tsh is measured as the distance from the tread profile to the outer periphery of the extended belt cord.

[0147] Furthermore, the distance Tsh [mm] from the tread profile at the tire contact point T to the outer periphery of the wide cross belt 141, relative to the distance Tce [mm] on the tire equatorial plane CL, preferably satisfies the following formula (9). Wherein, Gmin=0.36, Gmax=0.72, preferably Gmin=0.37, Gmax=0.71, more preferably Gmin=0.38, Gmax=0.70.

[0148] [Formula 9]

[0149]

[0150] also, Figure 5 The document defines a range of width ΔTW that is 10% of the tire contact patch width TW. At this point, the ratio of the maximum value Ta to the minimum value Tb of the tread rubber 15 in any range of the tire contact patch area is within the range of 0% to 40%, preferably within the range of 0% to 20%. In this configuration, the variation in the rubber thickness of the tread rubber 15 in any range of the tire contact patch area (particularly including the ends of the belt ply layers 141 to 144) is set to be small, thus smoothing the distribution of contact pressure in the tire width direction and improving the tire's wear resistance.

[0151] The rubber thickness of tread rubber 15 is defined as the distance from the tread profile to the inner circumferential surface of tread rubber 15 (in Figure 5 In this context, is the distance from the outer peripheral surface of the crown tread 151 to the inner peripheral surface of the base tread 152. Therefore, excluding the grooves formed on the tread tread surface, the rubber thickness of the tread rubber 15 is measured.

[0152] In addition, Figure 5 In this embodiment, the rubber thickness UTce of the base tread 152 on the tire equatorial plane CL, relative to the distance Tce on the tire equatorial plane CL, is in the range of 0.04 ≤ UTce / Tce ≤ 0.60, and preferably in the range of 0.06 ≤ UTce / Tce ≤ 0.50. This optimizes the rubber thickness UTce of the base tread 152.

[0153] Furthermore, the distance Tsh at the tire ground contact point T mentioned above is relative to the innermost layer of belt layer 14 (in Figure 5In this context, the rubber thickness Tu [mm] from the end of the wide cross-belt 141 to the outer periphery of the carcass layer 13 is in the range of 1.50 ≤ Tsh / Tu ≤ 30.0, preferably in the range of 2.00 ≤ Tsh / Tu ≤ 6.70. This optimizes the profile of the carcass layer 13, thereby optimizing its tension. Specifically, the lower limit ensures the carcass layer tension and the tread thickness in the shoulder area, thus suppressing repeated tire deformation during rolling and ensuring the tire's wear resistance. The upper limit ensures the rubber thickness near the ends of the belt ply, thus suppressing the separation of the peripheral rubber of the belt ply.

[0154] The rubber thickness Tu is essentially the innermost layer of the inserted belt layer 14 (in Figure 5 In the middle, the rubber component between the end of the wide cross belt 141 and the carcass layer 13 (in Figure 5 The thickness of the sidewall rubber (16) was measured in the middle.

[0155] The outer peripheral surface of the carcass layer 13 is defined as the entire radially outer peripheral surface of the carcass ply composed of carcass cords and coated rubber. Furthermore, when the carcass layer 13 has a multi-layered structure composed of multiple carcass plies (see...), Figure 1 When the outermost carcass ply 13B is in the outermost position, the outer peripheral surface of the carcass ply 13 constitutes the outer peripheral surface of the carcass ply 13. Furthermore, when the upper rolled portion 132 of the carcass ply 13 (see...) Figure 1 When the upper roll portion 132 exists between the innermost end of the belt layer 14 and the carcass layer 13 (illustration omitted), the outer peripheral surface of the upper roll portion 132 constitutes the outer peripheral surface of the carcass layer 13.

[0156] For example, in Figure 5 In this configuration, the sidewall rubber 16 is inserted between the end of the wide cross-belt 141 and the carcass layer 13, thereby forming a rubber thickness Tu between the end of the wide cross-belt 141 and the carcass layer 13. However, the configuration of the sidewall rubber 16 is not limited to this. For example, the belt layer separator rubber may be used instead of the sidewall rubber 16 to be inserted between the end of the wide cross-belt 141 and the carcass layer 13 (illustration omitted). Furthermore, the inserted rubber member has a rubber hardness Hs_sp of 46 or more and 67 or less, a modulus M_sp [MPa] at 100% elongation of 1.0 or more and 3.5 or less, and a loss tangent tanδ_sp of 0.02 or more and 0.22 or less. Preferably, it has a rubber hardness Hs_sp of 48 or more and 63 or less, a modulus M_sp [MPa] at 100% elongation of 1.2 or more and 3.2 or less, and a loss tangent tanδ_sp of 0.04 or more and 0.20 or less.

[0157] In addition, Figure 1In its configuration, the tire 1 has multiple circumferential main grooves 21-23 extending along the tire circumferential direction on the tread surface (see... Figure 5 ), and the annular land portion (symbols omitted in the figure) divided by these circumferential main grooves 21-23. The main groove is defined as the groove having the display obligation of the wear indicator specified by JATMA.

[0158] At this time, as Figure 5 As shown, the groove depth Gd1 [mm] of the circumferential main groove 21, which is closest to the tire equatorial plane CL among the multiple circumferential main grooves 21 to 23, is in the range of 0.50 ≤ Gd1 / Gce ≤ 1.00 relative to the rubber thickness Gce [mm] of the tread rubber 15, preferably in the range of 0.55 ≤ Gd1 / Gce ≤ 0.98. This ensures the tire's wear resistance. Specifically, the lower limit mentioned above disperses the ground pressure in the central area of ​​the tread, thereby improving the tire's wear life. The upper limit mentioned above ensures the rigidity of the circumferential rim and the rubber thickness from the bottom of the circumferential main groove 21 to the belt layer.

[0159] The circumferential main groove closest to the tire equatorial plane CL is defined as the circumferential main groove 21 located on the tire equatorial plane CL (see [reference]). Figure 5 If there is no circumferential main groove on the tire equatorial plane CL (illustration omitted), it is defined as the circumferential main groove closest to the tire equatorial plane CL.

[0160] Furthermore, the ratio Gd1 / Gce relative to the tire outer diameter OD [mm] preferably satisfies the following formula (10). Wherein, Hmin=0.10, Hmax=0.60, preferably Hmin=0.12, Hmax=0.50, more preferably Hmin=0.14, Hmax=0.40.

[0161] [Formula 10]

[0162]

[0163] In addition, the groove depth Gd1 [mm] of the circumferential main groove 21 closest to the tire equatorial plane CL among the multiple circumferential main grooves 21 to 23 is deeper than the groove depths Gd2 [mm] and Gd3 [mm] of the other circumferential main grooves 22 and 23 (Gd2 < Gd1, Gd3 < Gd1). Specifically, when the region from the tire equatorial plane CL to the tire ground end T is bisected in the tire width direction, the groove depth Gd1 of the circumferential main groove (omitted in the figure) closest to the tire equatorial plane CL is within a range of not less than 1.00 times and not more than 2.50 times, preferably within a range of not less than 1.00 times and not more than 2.00 times, and more preferably within a range of not less than 1.00 times and not more than 1.80 times, with respect to the maximum value of the groove depths Gd2 and Gd3 of the other circumferential main grooves (omitted in the figure) in the region on the tire ground end T side. By the above lower limit, the ground pressure in the central region of the tread can be dispersed, thereby improving the wear resistance of the tire. By the above upper limit, uneven wear caused by an excessive ground pressure difference between the central region and the shoulder region of the tread can be suppressed.

[0164] [Side profile and side thickness]

[0165] Figure 6 To show Figure 1 an enlarged view of the sidewall portion and the bead portion of the tire 1 described in Figure 7 To show Figure 6 an enlarged view of the sidewall portion described in

[0166] Figure 6 defines points Au on the side profile at the same radial position with respect to the end of the innermost layer of the belt layer 14 (in Figure 6 it is the inner diameter side cross belt 141) and points Al on the side profile at the same radial position with respect to the radially outer end of the bead core 11. In addition, the distance Hu in the tire radial direction from the tire maximum width position Ac to point Au and the distance Hl in the tire radial direction from the tire maximum width position Ac to point Al are defined. In addition, points Au' on the side profile at the radial position 70 [%] of the distance Hu from the tire maximum width position Ac and points Al' on the side profile at the radial position 70 [%] of the distance Hl from the tire maximum width position Ac are defined.

[0167] At this time, the sum of the distance Hu [mm] and the distance Hl [mm] with respect to the tire section height SH [mm] (see Figure 2The value is preferably within the range of 0.45 ≤ (Hu + Hl) / SH ≤ 0.90, and more preferably within the range of 0.50 ≤ (Hu + Hl) / SH ≤ 0.85. This optimizes the radial distance from the belt layer 14 to the bead core 11. Specifically, the lower limit ensures the deformable area of ​​the sidewall, thereby suppressing sidewall defects (e.g., separation of the rubber component at the radially outer end of the bead core 12). The upper limit reduces the deflection of the sidewall during tire rolling, thus reducing rolling resistance.

[0168] Distances Hu and Hl are measured under no-load conditions while the tires are mounted on the specified rims and subjected to the specified internal pressure.

[0169] Furthermore, the sum of distances Hu [mm] and Hl [mm] is relative to the tire outer diameter OD ( Figure 1 Tire section height SH [mm] (see) Figure 2 The radius of curvature RSc [mm] of the arc passing through the maximum width position Ac, point Au' and point Al' of the tire is preferably satisfied by the following formula (11). Wherein, I1min=0.06, I1max=0.20, I2=0.70, preferably I1min=0.09, I1max=0.20, I2=0.65.

[0170] [Formula 11]

[0171]

[0172] The radius of curvature RSc of the arc is measured under no-load conditions while the tire is mounted on a specified rim and subjected to a specified internal pressure.

[0173] Furthermore, the distances Hu [mm] and Hl [mm] have a relationship of 0.30 ≤ Hu / (Hu+Hl) ≤ 0.70, and preferably a relationship of 0.35 ≤ Hu / (Hu+Hl) ≤ 0.65. This allows for optimization of the position of the maximum tire width Ac in the deformable region of the tire sidewall. Specifically, the lower limit mentioned above mitigates stress concentration near the end of the belt ply caused by the maximum tire width Ac being too close to the end of the belt ply 14, thereby suppressing the separation of the surrounding rubber. The upper limit mentioned above mitigates stress concentration near the bead portion caused by the maximum tire width Ac being too close to the end of the bead core 11, thereby suppressing the stress concentration of the reinforcing member (in the bead portion)... Figure 6 The fault is in the tire sidewall core 12.

[0174] Furthermore, the radius of curvature RSc [mm] of the arc passing through the tire's maximum width position Ac, point Au', and point Al' is in the range of 0.05 ≤ RSc / OD ≤ 1.70 relative to the tire's outer diameter OD [mm], preferably in the range of 0.10 ≤ RSc / OD ≤ 1.60. Additionally, the radius of curvature RSc [mm] of the arc is in the range of 25 ≤ RSc ≤ 330, preferably in the range of 30 ≤ RSc ≤ 300. This optimizes the radius of curvature of the sidewall profile, thereby appropriately ensuring the load-bearing capacity of the tire sidewall. Specifically, the lower limit reduces the deflection of the tire sidewall during rolling, thus reducing rolling resistance. The upper limit suppresses stress concentration caused by sidewall flattening, thereby improving tire durability. Especially for small-diameter tires, there is a tendency for greater stress to be generated on the sidewall under high internal pressure and high load, therefore, ensuring the tire's resistance to sidewall shearing is also a concern. In this respect, the lower limit mentioned above ensures the radius of curvature of the side profile and optimizes tire tension, thereby suppressing tire collapse and thus inhibiting tire sidewall cutting. Furthermore, the upper limit mentioned above can suppress tire sidewall cutting caused by excessive tension in the carcass layer 13.

[0175] Furthermore, the radius of curvature RSc [mm] of the arc is in the range of 0.50 ≤ RSc / SH ≤ 0.95 relative to the tire section height SH [mm], preferably in the range of 0.55 ≤ RSc / SH ≤ 0.90.

[0176] Furthermore, the radius of curvature RSc [mm] of the arc is preferably satisfied by the following formula (12) relative to the tire outer diameter OD [mm] and the rim diameter RD [mm]. Wherein, Jmin=15, Jmax=360, preferably Jmin=20, Jmax=330, more preferably Jmin=25, Jmax=300.

[0177] [Formula 12]

[0178]

[0179] also, Figure 6 A point Bc is defined on the main body 131 of the innermost carcass ply 13A, which is located at the same radial position relative to the tire's maximum width position Ac. Furthermore, a point Bu' is defined on the main body 131 of the innermost carcass ply 13A at a radial position 70% of the aforementioned distance Hu from the tire's maximum width position Ac. Additionally, a point Bl' is defined on the main body 131 of the innermost carcass ply 13A at a radial position 70% of the aforementioned distance Hl from the tire's maximum width position Ac.

[0180] At this point, the radius of curvature RSc [mm] of the arc passing through the maximum tire width positions Ac, Au', and Al' is in the range of 1.10 ≤ RSc / RCc ≤ 4.00, and preferably in the range of 1.50 ≤ RSc / RCc ≤ 3.50, relative to the radius of curvature RCc [mm] of the arc passing through Bc, Bu', and Bl'. Furthermore, the radius of curvature RCc [mm] of the arc passing through Bc, Bu', and Bl' is in the range of 5 ≤ RCc ≤ 300, and preferably in the range of 10 ≤ RCc ≤ 270. This optimizes the relationship between the radius of curvature RSc of the tire's side profile and the radius of curvature RCc of the side profile of the carcass layer 13. Specifically, by using the lower limit, the radius of curvature RCc of the carcass profile can be ensured, and the tire volume V (described later) can be ensured, thereby ensuring the tire's load capacity. By using the upper limit, the total thicknesses Gu and Gl of the sidewall portion (described later) can be ensured, thereby ensuring the load capacity of the sidewall portion.

[0181] Furthermore, the radius of curvature RSc [mm] of the aforementioned side profile is preferably satisfied by the following formula (13) relative to the radius of curvature RCc [mm] of the aforementioned carcass profile and the tire outer diameter OD [mm]. Wherein, Kmin=1, Kmax=130, preferably Kmin=2, Kmax=100, more preferably Kmin=3, Kmax=70.

[0182] [Formula 13]

[0183]

[0184] In addition, Figure 6 In this context, the total thickness Gu [mm] of the sidewall portion at point Au is within the range of 0.010 ≤ Gu / OD ≤ 0.080 relative to the tire outer diameter OD [mm], preferably within the range of 0.017 ≤ Gu / OD ≤ 0.070. This optimizes the total thickness Gu of the radially outer region of the sidewall. Specifically, by using the lower limit, the total thickness Gu of the radially outer region of the sidewall is ensured, suppressing tire deformation under high loads and thus ensuring tire wear resistance. Especially for small-diameter tires, their use under high internal pressure and high loads is foreseeable, thus significantly achieving the aforementioned reduction in tire rolling resistance. By using the upper limit, the reduction in tire rolling resistance caused by excessive total thickness Gu is suppressed.

[0185] The total thickness of the sidewall portion is measured as the distance from the sidewall profile to the inner surface of the tire on a vertical line drawn from a predetermined point on the sidewall profile to the main body 131 of the carcass layer 13.

[0186] In addition, Figure 6In this context, the total thickness Gu [mm] at point Au, relative to the total thickness Gc [mm] of the sidewall portion at the tire's maximum width position Ac, is within the range of 1.20 ≤ Gu / Gc ≤ 5.00, and preferably the ratio Gu / Gc is within the range of 1.30 ≤ Gu / Gc ≤ 3.00. This optimizes the thickness distribution of the sidewall portion from the tire's maximum width position Ac to the innermost layer of the belt layer 14. Specifically, by using the lower limit, the total thickness Gu in the radially outer region can be ensured, suppressing tire deformation under high loads and thus ensuring tire wear resistance. By using the upper limit, the reduction in tire rolling resistance caused by excessive total thickness Gu can be suppressed.

[0187] Furthermore, the total thickness Gu [mm] at point Au, relative to the total thickness Gc [mm] at the maximum tire width position Ac and the tire outer diameter OD [mm], preferably satisfies the following formula (14). Wherein, Lmin=0.10, Lmax=0.70, preferably Lmin=0.14, Lmax=0.70, more preferably Lmin=0.19, Lmax=0.70.

[0188] [Formula 14]

[0189]

[0190] In addition, Figure 6 In this design, the total thickness Gc [mm] of the sidewall portion at the tire's maximum width position Ac has a relationship of 0.003 ≤ Gc / OD ≤ 0.060 relative to the tire's outer diameter OD [mm], preferably 0.004 ≤ Gc / OD ≤ 0.050. This lower limit ensures the total thickness Gc at the tire's maximum width position Ac, thereby ensuring the tire's load-bearing capacity. The upper limit ensures the reduction in rolling resistance caused by thinning the total thickness Gc at the tire's maximum width position Ac.

[0191] Furthermore, the total thickness Gc[mm] at the maximum width position Ac of the tire, relative to the tire outer diameter OD[mm], preferably satisfies the following formula (15). Wherein, Mmin=70, Mmax=450, preferably Mmin=80, Mmax=400.

[0192] [Formula 15]

[0193]

[0194] Furthermore, the total thickness Gc [mm] at the maximum tire width position Ac preferably satisfies the following formula (16) relative to the tire outer diameter OD [mm] and the total tire width SW [mm]. Wherein, Nmin=0.20, Nmax=15, preferably Nmin=0.40, Nmax=15, more preferably Nmin=0.60, Nmax=12.

[0195] [Formula 16]

[0196]

[0197] Furthermore, the total thickness Gc [mm] at the maximum tire width position Ac, relative to the radius of curvature RSc [mm] of the arc passing through the maximum tire width position Ac, point Au', and point Al', preferably satisfies the following formula (17). Wherein, Omin=13, Omax=260, preferably Omin=20, Omax=200.

[0198] [Formula 17]

[0199]

[0200] In addition, Figure 6 In this context, the total thickness Gl [mm] of the sidewall at point A1 is within the range of 0.010 ≤ Gl / OD ≤ 0.150 relative to the tire outer diameter OD [mm], preferably within the range of 0.015 ≤ Gl / OD ≤ 0.100. This optimizes the total thickness Gl of the radially inner region of the sidewall. Specifically, by using the lower limit, the total thickness Gl of the radially inner region of the sidewall is ensured, suppressing tire deformation under high loads and thus ensuring tire wear resistance. Especially for small-diameter tires, their use under high internal pressure and high loads is foreseeable, thus significantly achieving the aforementioned reduction in tire rolling resistance. By using the upper limit, the reduction in tire rolling resistance caused by excessive total thickness Gl is suppressed.

[0201] In addition, Figure 6 In this context, the ratio Gl / Gc of the total thickness Gl [mm] of the sidewall portion at point A1 to the total thickness Gc [mm] of the sidewall portion at the tire's maximum width position Ac is within the range of 1.00 ≤ Gl / Gc ≤ 7.00, and preferably within the range of 2.00 ≤ Gl / Gc ≤ 5.00. This optimizes the thickness distribution of the sidewall portion from the tire's maximum width position Ac to the bead core 11. Specifically, by using the lower limit, the total thickness Gl in the radially inner region can be ensured, suppressing tire deformation under high loads and thus ensuring the tire's wear resistance. By using the upper limit, the reduction in tire rolling resistance caused by excessive total thickness Gl can be suppressed.

[0202] In addition, the total thickness Gl [mm] of the sidewall portion at the above-mentioned point Al is preferably such that it satisfies the following formula (18) with respect to the total thickness Gc [mm] at the maximum width position Ac of the tire and the outer diameter OD [mm] of the tire. Here, Pmin = 0.12, Pmax = 1.00, preferably Pmin = 0.15, Pmax = 1.00, and more preferably Pmin = 0.18, Pmax = 1.00.

[0203] [Formula 18]

[0204]

[0205] In addition, in Figure 6 , the total thickness Gl [mm] at the above-mentioned point Al is within the range of 0.80 ≤ Gl / Gu ≤ 5.00 with respect to the total thickness Gu [mm] at the above-mentioned point Au, preferably within the range of 0.85 ≤ Gl / Gu ≤ 4.00. Thereby, the ratio of the total thickness Gl in the radially outer region of the sidewall portion to the total thickness Gu in the radially inner region can be optimized.

[0206] In addition, the total thickness Gl [mm] at the above-mentioned point Al is preferably such that it satisfies the following formula (19) with respect to the total thickness Gu [mm] at the above-mentioned point Au and the outer diameter OD [mm] of the tire. Here, Qmin = 0.09, Qmax = 0.80, preferably Qmin = 0.10, Qmax = 0.70, and more preferably Qmin = 0.11, Qmax = 0.50.

[0207] [Formula 19]

[0208]

[0209] In addition, in Figure 6 , the average rubber hardness Hsc at the measurement position of the total thickness Gc, the average rubber hardness Hsu at the measurement position of the total thickness Gu, and the average rubber hardness HsI at the measurement position of the total thickness Gl have the relationship of Hsc ≤ Hsu < HsI, preferably having the relationship of 1 ≤ Hsu - Hsc ≤ 18 and 2 ≤ HsI - Hsu ≤ 27, and more preferably having the relationship of 2 ≤ Hsu - Hsc ≤ 15 and 5 ≤ HsI - Hsu ≤ 23. Thereby, the relationship between the rubber hardnesses of the sidewall portion can be optimized.

[0210] The average rubber hardnesses Hsc, Hsu, and HsI are calculated in such a way that it is the sum of the products of the cross-sectional lengths and the rubber hardnesses of the respective rubber members at the respective measurement points of the total thickness Gc [mm] at the maximum width position Ac of the tire, the total thickness Gu at the point Au, and the total thickness Gl at the point Al, divided by the total thickness.

[0211] In addition, Figure 7 In this case, the distance ΔAu' [mm] from the tire's maximum width position Ac to point Au' in the tire width direction is within the range of 0.03 ≤ ΔAu' / (Hu×0.70) ≤ 0.23, and preferably within the range of 0.07 ≤ ΔAu' / (Hu×0.70) ≤ 0.17, relative to 70% of the distance Hu [mm] from the tire's maximum width position Ac. This optimizes the curvature of the side profile in the radially outer region. Specifically, by using the lower limit, stress concentration caused by flattening of the tire sidewall can be suppressed, thereby improving tire durability. By using the upper limit, the deflection of the tire sidewall during tire rolling can be reduced, thereby reducing rolling resistance. Especially for small-diameter tires, there is a tendency for greater stress to be generated on the tire sidewall due to use under high internal pressure and high load, therefore, there is also the issue of ensuring the tire's resistance to sidewall shearing. In this respect, the lower limit mentioned above ensures the radius of curvature of the side profile and optimizes tire tension, thereby suppressing tire collapse and thus inhibiting tire sidewall cutting. Furthermore, the upper limit mentioned above can suppress tire sidewall cutting caused by excessive tension in the carcass layer 13.

[0212] Furthermore, the distance ΔAl' [mm] in the tire width direction from the maximum tire width position Ac to point Al' is within the range of 0.03 ≤ ΔAl' / (Hl×0.70) ≤ 0.28, preferably within the range of 0.07 ≤ ΔAl' / (Hl×0.70) ≤ 0.20, relative to 70% of the distance Hl [mm] from the maximum tire width position Ac. This optimizes the curvature of the side profile in the radially inner region. Specifically, by using the aforementioned lower limit, stress concentration caused by flattening of the tire sidewall can be suppressed, thereby improving tire durability. Especially for small-diameter tires, the bead core 11 can be strengthened as described above, thus effectively suppressing stress concentration near the bead core 11. By using the aforementioned upper limit, the deflection of the tire sidewall during tire rolling can be reduced, thereby reducing tire rolling resistance.

[0213] The distances ΔAu' and ΔAl' are measured under no-load conditions while the tire is mounted on the specified rim and subjected to the specified internal pressure.

[0214] Furthermore, the distance ΔAu' [mm] from the tire's maximum width position Ac to point Au' in the tire width direction, relative to the radius of curvature RSc [mm] of the arc passing through the tire's maximum width position Ac, point Au', and point Al', preferably satisfies the following formula (20). Wherein, Rmin=0.05, Rmax=5.00, preferably Rmin=0.10, Rmax=4.50.

[0215] [Formula 20]

[0216]

[0217] In addition, Figure 7 In this context, the distance ΔBu' [mm] in the tire width direction from point Bc to point Bu' is within the range of 1.10 ≤ ΔBu' / ΔAu' ≤ 8.00, and preferably within the range of 1.60 ≤ ΔBu' / ΔAu' ≤ 7.50, relative to the distance ΔAu' [mm] in the tire width direction from the maximum tire width position to point Au'. This optimizes the relationship between the curvature of the side profile and the curvature of the tire carcass in the radially outer region. Specifically, the lower limit ensures the cut resistance of the tire sidewall. The upper limit ensures the tension of the carcass layer 13, ensuring the rigidity of the tire sidewall, thereby ensuring the tire's load capacity and durability.

[0218] In addition, Figure 7 In this context, the distance ΔBl' [mm] in the tire width direction from point Bc to point Bl' is within the range of 1.80 ≤ ΔBl' / ΔAl' ≤ 11.0, and preferably within the range of 2.30 ≤ ΔBl' / ΔAl' ≤ 9.50, relative to the distance ΔAl' [mm] in the tire width direction from the maximum tire width position Ac to point Al'. This optimizes the relationship between the curvature of the side profile and the curvature of the tire carcass in the radially inner region. Specifically, the lower limit ensures the total thickness Gl of the tire sidewall, thereby ensuring the load-bearing capacity of the tire sidewall. The upper limit ensures the tension of the carcass layer 13, ensuring the rigidity of the tire sidewall, thereby ensuring the tire's load-bearing capacity and durability.

[0219] The distances ΔBu' and ΔBl' are measured under no-load conditions while the tires are mounted on the specified rims and subjected to the specified internal pressure.

[0220] Furthermore, the distance ΔBu' [mm] in the tire width direction from point Bc to point Bu' preferably satisfies the following formula (21) relative to the radius of curvature RCc [mm] of the arc passing through the aforementioned points Bc, Bu', and Bl'. Wherein, Smin=0.40, Smax=7.0, preferably Smin=0.50, Smax=6.0.

[0221] [Formula 21]

[0222]

[0223] In addition, Figure 7In this configuration, the rubber thickness Gcr [mm] of the sidewall rubber 16 at the maximum tire width position Ac is within the range of 0.40 ≤ Gcr / Gc ≤ 0.90 relative to the total thickness Gc [mm] at the maximum tire width position Ac. Furthermore, the rubber thickness Gcr [mm] of the sidewall rubber 16 is within the range of 1.5 ≤ Gcr, preferably within the range of 2.5 ≤ Gcr. By meeting these lower limits, the rubber thickness Gcr [mm] of the sidewall rubber 16 can be ensured, thereby ensuring the load-bearing capacity of the sidewall portion.

[0224] Furthermore, the rubber thickness Gcr [mm] of the sidewall rubber 16 at the maximum tire width position Ac, relative to the total thickness Gc [mm] at the maximum tire width position Ac and the tire outer diameter OD [mm], preferably satisfies the following formula (22). Wherein, Tmin=80, Tmax=0.90, preferably Tmin=120, Tmax=0.90.

[0225] [Formula 22]

[0226]

[0227] In addition, Figure 7 In this configuration, the rubber thickness Gin [mm] (illustration omitted) of the inner liner 18 at the maximum tire width position Ac is within the range of 0.03 ≤ Gin / Gc ≤ 0.50, preferably within the range of 0.05 ≤ Gin / Gc ≤ 0.40, relative to the total thickness Gc [mm] at the maximum tire width position Ac. This provides adequate protection for the inner surface of the carcass layer 13.

[0228] [Carcass ply and belt ply]

[0229] Figure 8 It means Figure 1 This diagram illustrates the laminated structure of the tire's carcass and belt layers as described in the text. The diagram shows an enlarged view of the tire's cross-sectional section along the radial direction.

[0230] exist Figure 1 In its composition, such as Figure 8 As shown, the carcass layer 13 is formed by laminating two carcass ply layers 13A and 13B made of carcass cords 13cc coated with coated rubber 13cr. Furthermore, the belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and an additional belt 145 made of belt cords 14bc coated with coated rubber 14cr. Additionally, the inner liner 18 covers the inner circumferential surface of the carcass layer 13.

[0231] In addition, Figure 8 In the middle, from the innermost carcass ply (in Figure 8In the figure, TL [mm] is the distance from the center of the outer diameter of the carcass cord 13cc of the inner diameter sidewall (13A) to the inner surface of the tire relative to the outer diameter OD [mm] of the tire (see [reference]). Figure 1 The distance TL [mm] is preferably within the range of 0.001 ≤ TL / OD ≤ 0.009, and more preferably within the range of 0.002 ≤ TL / OD ≤ 0.008. Furthermore, the distance TL [mm] is relative to the total tire width SW [mm] (see...). Figure 1 The pressure is preferably within the range of 0.003 ≤ TL / SW ≤ 0.025, and more preferably within the range of 0.004 ≤ TL / SW ≤ 0.020. The lower limit above this value can appropriately suppress air leakage; the upper limit above this value can suppress the increase in tire weight.

[0232] The distance TL [mm] is calculated for the two points B2 and B2 mentioned above (see...). Figure 4 The average value in the region between ).

[0233] In addition, the distance TL [mm] is relative to the total tire width SW [mm], tire outer diameter OD [mm], and rim diameter RD [mm] (see [reference]). Figure 1 The range is 1 / 80000≤TL / (SW×(OD-RD))≤1 / 3760.

[0234] In addition, Figure 8 In the middle, from the innermost carcass ply (in Figure 8 In this context, the distance TCSU [mm] from the center of the carcass cord 13cc of the innermost carcass ply 13A to the outer surface of the innermost carcass ply 13A, relative to the distance TL [mm] from the center of the carcass cord 13cc of the innermost carcass ply 13A to the inner surface of the tire, is within the range of 0.09 ≤ TCSU / TL ≤ 1.00, preferably within the range of 0.10 ≤ TCSU / TL ≤ 0.90. By using the lower limit mentioned above, air leakage can be appropriately suppressed; by using the upper limit mentioned above, the increase in tire weight can be suppressed.

[0235] In addition, Figure 8In this process, the modulus MC [MPa] of the coated rubber 13cr of the carcass ply 13A and 13B at 100% elongation relative to the modulus MIL [MPa] of the inner liner 18 at 100% elongation, and the modulus MB [MPa] of the coated rubber 14cr of the innermost belt ply 141 of the belt layer 14 at 100% elongation, are in the range of MIL ≤ MC ≤ MB. Furthermore, the ratio MC / MIL is in the range of 1.00 ≤ MC / MIL ≤ 3.00, preferably in the range of 1.10 ≤ MC / MIL ≤ 2.30. Furthermore, the ratio MB / MC is in the range of 1.00 ≤ MB / MC ≤ 2.40, preferably in the range of 1.00 ≤ MB / MC ≤ 2.00. Furthermore, the modulus MC [MPa] of the coating rubber 13cr of the carcass plies 13A and 13B is in the range of 1.5 ≤ MC ≤ 12.0, preferably in the range of 2.0 ≤ MC ≤ 10.0. This effectively suppresses air leakage and ensures tire durability.

[0236] In addition, Figure 8 In this tire, the product of the thickness TC [mm] of the carcass ply layers 13A and 13B and the loss tangent tanδ of the coating rubber 13cr of the carcass ply layers 13A and 13B at 60 [°C] is in the range of 0.08 ≤ TC × tanδ ≤ 0.45, preferably in the range of 0.10 ≤ TC × tanδ ≤ 0.40. This effectively suppresses heat generation in the carcass ply layer 13 and ensures tire durability.

[0237] Furthermore, when the carcass cords 13cc of the carcass ply 13A and 13B are made of organic fiber material, the cord diameter φcs [mm] of the carcass cord 13cc relative to the breaking strength Tcs [N / 50mm] of the carcass ply 13A and 13B, the number of layers Pcs [layers] of the carcass ply 13A and 13B, and the sum of the density of the carcass cords in one carcass ply 13A and 13B, Ncs [roots] preferably satisfies the following formula (23).

[0238] [Formula 23]

[0239]

[0240] Furthermore, when the carcass cords 13cc of the carcass ply 13A and 13B are made of organic fiber material, the density Ecs [cords / 50mm] relative to the cord diameter φcs [mm] of the carcass cords 13cc preferably satisfies the following formula (24).

[0241] [Formula 24]

[0242]

[0243] In addition, Figure 8 In the process, when the carcass cords 13cc of the carcass ply 13A and 13B are made of organic fiber material, the outermost carcass ply 13B of the carcass ply 13 and the innermost belt ply of the belt ply 14 (in Figure 8 In this configuration, the peel force Hpp [N / 25mm] per 25mm width of the inner diameter side cross belt 141, relative to the distance TCB [mm] from the outer diameter center of the carcass cord 13cc of the carcass ply 13B to the outer diameter center of the belt cord 14bc of the belt ply 141, is in the range of 90 ≤ Hpp / TCB ≤ 300, preferably in the range of 100 ≤ Hpp / TCB ≤ 250. Furthermore, the peel force Hpp [N / 25mm] relative to the density Ecs [roots / 50mm] of the carcass cord 13cc of the carcass ply is in the range of 1.50 ≤ Hpp / Ecs ≤ 15.0, preferably in the range of 1.80 ≤ Hpp / Ecs ≤ 10.0. This ensures the tire's durability.

[0244] Using a test sample having a rectangular shape extending in the direction of the carcass cords and having a width of 25 mm and a length of 100 mm or more (preferably 150 mm or more including a test clamping end of about 50 mm), the average of the maximum and minimum values ​​of the peak values ​​of the analyzed wavy curve is calculated and taken as the peel force Hpp [N / 25 mm]. Furthermore, it is preferable to use two or more test samples.

[0245] In addition, Figure 8 In the process, when the carcass cords 13cc of the carcass ply 13A and 13B are made of organic fiber material, the outermost carcass ply 13B of the carcass ply 13 and the innermost belt ply of the belt ply 14 (in Figure 8 In the middle, the peel force Hpp [N / 25mm] per 25 [mm] width of the inner diameter side cross belt 141) relative to the distance TCB from the center of the outer diameter of the carcass cord 13cc of the outermost carcass ply 13B of the carcass layer 13 to the center of the outer diameter of the belt cord 14bc of the innermost belt ply 141 of the belt layer 14, the cord diameter φcs [mm] of the carcass cord 13cc, and the density Ecs [roots / 50mm] preferably satisfy the following formula (25).

[0246] [Formula 25]

[0247]

[0248] also, Figure 8 The distance Hb between the cords of adjacent cord layers in a pair of cross-belt bundles 141, 142 and additional bundle 145 is defined (in Figure 8In this context, the inter-cord distance Hb1 is the distance between the cords of a pair of cross belts 141 and 142, and the inter-cord distance Hb2 is the distance between the cords of the outer diameter side cross belt and the additional belt 145. At this time, the inter-cord distance Hb_sh (not shown) at the end of at least one set of belt ply layers is in the range of 1.05 ≤ Hb_sh / Hb_ce ≤ 2.00 relative to the inter-cord distance Hb_ce (not shown) on the tire equatorial plane CL, preferably in the range of 1.50 ≤ Hb_sh / Hb_ce ≤ 1.80. Therefore, it is preferable to set the inter-cord distance Hb to be larger in the central region of the tread. With the lower limit mentioned above, the tire outer diameter increase suppression effect of the belt layer 14 can be effectively obtained; with the upper limit mentioned above, the durability of the belt layer can be ensured. This configuration is achieved, for example, by increasing the thickness of the coating rubber of the belt ply in the central region of the tread, or by inserting additional rubber plates between adjacent belt ply layers (notation omitted).

[0249] [Variation Example 1]

[0250] Figure 9 It means Figure 1 This is an explanatory diagram of a variation of tire 1 described herein. The diagram shows the laminated structure of the belt layer 14. In this diagram, the belt layer 14 is... Figure 3 Elements that are identical to those described herein shall be marked with the same symbol and their descriptions shall be omitted.

[0251] exist Figure 1 As described above, the belt layer 14 comprises a pair of cross belts 141 and 142, a belt cover layer 143, a pair of belt edge cover layers 144 and 145, and an additional belt 145. Furthermore, the cord angles θ41 and θ42 of the cross belts 141 and 142 are different in sign from each other and are in the range of 15 degrees or more and 55 degrees or less in absolute value.

[0252] In addition, such as Figure 3As shown, the additional belt 145 is stacked radially outside the pair of cross belts 141 and 142. Furthermore, the cord angle θ45 of the additional belt 145 has a different sign than the cord angle θ42 of the adjacent cross belt 142, and is in the range of 15 degrees or more and 80 degrees or less in absolute value relative to the tire circumference. Therefore, the additional belt 145 constitutes a third cross belt stacked on the pair of cross belts 141 and 142. Moreover, the width Wb5 of the additional belt 145 is wider than the width Wb2 of the adjacent cross belt 142, and is in the range of 1.03 ≤ Wb5 / Wb2 ≤ 1.40, preferably in the range of 1.05 ≤ Wb5 / Wb2 ≤ 1.25, relative to the width Wb2. Therefore, the end of the additional belt 145 is offset relative to the end of the adjacent cross belt 142 in the tire width direction. Therefore, the effect of the additional belt in suppressing the increase in tire outer diameter can be effectively obtained, and the durability of the belt layer 14 can be improved.

[0253] In contrast, Figure 9 In its configuration, the additional belt 145 is stacked radially inside a pair of cross belts 141, 142, thereby being located on the inner diameter side of the cross belt 141 and the carcass layer 13 (see...). Figure 1 The additional belt 145 is a so-called high-angle belt, and its cord angle θ45 is larger than that of the inner diameter side cross belt 141, and is preferably in the range of 45 degrees or more and 70 degrees or less, and more preferably in the range of 54 degrees or more and 68 degrees or less, in absolute value relative to the tire circumference. Furthermore, the width Wb5 of the additional belt 145 is in the range of 0.60 ≤ Wb5 / Wb1 ≤ 1.40, and preferably in the range of 0.70 ≤ Wb5 / Wb1 ≤ 1.30, relative to the width Wb1 of the inner diameter side cross belt 141. Therefore, the end of the additional belt 145 is offset relative to the end of the adjacent cross belt 141 in the tire width direction. This effectively achieves the tire outer diameter increase suppression effect of the additional belt and improves the durability of the belt layer 14.

[0254] In addition, Figure 3 and Figure 9 In the middle, the belt cord of the additional belt 145 and the cross belt adjacent to the additional belt 145 in a pair of cross belts 141, 142 (in Figure 3 In the middle, there is the outer diameter side cross belt 142; in Figure 9In this configuration, the angle Δθ [deg] (not shown) formed by the belt cords of the inner diameter side cross belt 141 is in the range of 10 [deg] ≤ Δθ [deg] ≤ 90 [deg], preferably in the range of 20 [deg] ≤ Δθ [deg] ≤ 60 [deg], and more preferably in the range of 30 [deg] ≤ Δθ [deg] ≤ 55 [deg]. This effectively suppresses the increase in the outer diameter of the tire and ensures the durability of the belt layer 14.

[0255] Furthermore, the angle Δθ formed by the aforementioned cord angles relative to the tire outer diameter OD [mm] preferably satisfies the following formula (26). Wherein, Wmin=30, Wmax=330, preferably Wmin=60, Wmax=220, more preferably Wmin=90, Wmax=210.

[0256] [Formula 26]

[0257]

[0258] Furthermore, the smallest cord angle θmin[deg] among the cord angles of the effective cord layers 141, 142, 143, and 145 constituting the cord layer 14 (in Figure 3 and Figure 9 In the above, the breaking strength Tbt [N / 50mm] of the belt cover layer 144 relative to the belt fabric layer having the cord angle θ43) preferably satisfies the following formula (27). Wherein, Xmin=3, Xmax=410, preferably Xmin=3, Xmax=310, more preferably Xmin=30, Xmax=310.

[0259] [Formula 27]

[0260]

[0261] Furthermore, the angle formed by the cord angle of the innermost belted fabric layer and the cord angle of the second belted fabric layer is defined (in Figure 3 In the middle, the angle formed by the cord angles θ41 and θ42 of a pair of crossed belts 141 and 142; in Figure 9 In this context, Δθ12 [deg] is the angle formed by the cord angle θ45 of the additional belt 145 and the cross belt 141 on the inner diameter side. Furthermore, the angle formed by the cord angle of the second belted fabric layer and the cord angle of the third belted fabric layer is defined (in...). Figure 3In this context, Δθ12 and Δθ23 represent the angles formed by the cord angles θ42 of the outer diameter side cross belt 142 and θ45 of the additional belt 145, and the angles formed by the cord angles θ41 and θ42 of a pair of cross belts 141 and 142. At this time, these angles Δθ12 and Δθ23 [deg] have the relationship 50 ≤ Δθ12 + Δθ23 ≤ 100. Therefore, the increase in the outer diameter of the tire can be effectively suppressed, and the durability of the belt layer 14 can be ensured.

[0262] [Variation Example 2]

[0263] Figure 10 It means Figure 1 The diagram illustrates a variation of tire 1 as described in Example 2. In this diagram, the tire is oriented towards... Figure 3 Elements that are identical to those described herein shall be marked with the same symbol and their descriptions shall be omitted.

[0264] exist Figure 1 As described above, the belt layer 14 comprises a pair of cross belts 141, 142, a belt cover layer 143, a pair of belt edge cover layers 144, 144 and an additional belt 145.

[0265] But it is not limited to this, such as Figure 10 As shown, the additional belt 145 can also be omitted. This configuration can also adequately ensure the load-bearing capacity and durability of the belt layer 14.

[0266] [Variation Example 3]

[0267] Figure 11 It means Figure 1 The diagram illustrates a variation of tire 1 as described in Example 3. In this diagram, the tire is oriented towards... Figure 3 Elements that are identical to those described herein shall be marked with the same symbol and their descriptions shall be omitted.

[0268] exist Figure 1 As described above, the carcass layer 13 is composed of a pair of carcass plies 13A and 13B having a radial structure and a cord angle of 80 degrees or more and 100 degrees or less in absolute terms.

[0269] In contrast, Figure 11 In its composition, the carcass layer 13 is composed of a pair of carcass plies 13A' and 13B' having an offset structure and cord angles of 45 degrees or more and 70 degrees or less in absolute terms, with different signs from each other. Furthermore, [the remaining text is omitted]. Figure 1 The belt layer 14 in the structure. Thus, the above structure can also be used in bias tires.

[0270] [Effect]

[0271] As described above, the tire 1 includes a pair of bead cores 11, 11, a carcass layer 13 mounted on the bead cores 11, 11, and a belt layer 14 disposed radially outside the carcass layer 13 (see Figure 1 Furthermore, the tire outer diameter OD [mm] is in the range of 200 ≤ OD ≤ 660, and the total tire width SW [mm] is in the range of 100 ≤ SW ≤ 400. Furthermore, the carcass layer 13 is formed by laminating two carcass ply layers 13A and 13B made of organic fiber cords coated with coated rubber. Furthermore, the organic fiber cords of the two carcass ply layers 13A and 13B have cord angles in the range of 80 [deg] or more and 100 [deg] or less relative to the tire circumference. Furthermore, the breaking strength Tcs [N / 50mm] of each 50 [mm] width of the two carcass ply layers 13A and 13B is in the range of 17 ≤ Tcs / OD ≤ 120 relative to the tire outer diameter OD [mm].

[0272] With this configuration, the load-bearing capacity of the carcass layer 13 can be adequately ensured in small-diameter tires, thus achieving the advantages of balancing tire wear resistance and low rolling resistance. Specifically, by using the aforementioned lower limit ratio Tcs / OD, tire deformation under high loads can be suppressed, thereby ensuring tire wear resistance. Furthermore, it can be used under high internal pressure, reducing tire rolling resistance. Especially for small-diameter tires, their use under high internal pressure and high loads can be anticipated, thus significantly achieving the aforementioned tire wear resistance and rolling resistance reduction effects. By using the aforementioned upper limit ratio Tcs / OD, the reduction in rolling resistance caused by the increase in the mass of the carcass layers can be suppressed.

[0273] Furthermore, in this tire 1, from the two carcass plies 13A and 13B (see...) Figure 1 The distance TL [mm] from the center of the organic fiber cord 13cc of the inner diameter sidewall carcass ply 13A to the inner surface of the tire (see...) Figure 8 ) relative to the tire outer diameter OD [mm] (see Figure 1 Within the range of 0.001 ≤ TL / OD ≤ 0.009, it has the advantage of being able to appropriately suppress air leakage by the lower limit and suppress tire weight increase by the upper limit.

[0274] Furthermore, in this tire 1, the distance TCSU [mm] from the center of the organic fiber cord 13cc of the inner diameter side carcass ply 13A to the outer surface of the inner diameter side carcass ply 13A (see...) Figure 8The distance TL [mm] from the center of the organic fiber cord 13cc of the inner diameter sidewall carcass ply 13A to the inner surface of the tire is within the range of 0.09 ≤ TCSU / TL ≤ 1.00. This design has the advantage of being able to appropriately suppress air leakage at the lower limit and suppress tire weight increase at the upper limit.

[0275] Furthermore, the tire 1 has an inner liner 18 made of rubber material and disposed on the inner surface of the tire cavity to cover the carcass layer 13 (see Figure 1 Furthermore, the belt layer 14 is an organic fiber cord (belt cord 14bc) covered with coated rubber 14bc. See also Figure 8 Multi-layered belted fabric 141-145 (see) Figure 1 It is composed of layers. In addition, the modulus MC [MPa] of the coated rubber 13cr of the carcass ply 13A and 13B at 100% elongation is relative to the modulus MIL [MPa] of the inner liner 18 at 100% elongation, and the innermost belt ply of the belt layer 14 (in Figure 8 In the case of the inner diameter side cross belt 141), the modulus MB [MPa] of the coated rubber 14br at 100% elongation is within the range of MIL≤MC≤MB. Therefore, it has the advantage of being able to appropriately suppress air leakage and ensure tire durability.

[0276] Furthermore, in this tire 1, the modulus MC [MPa] of the coating rubber 13cr of the carcass plies 13A and 13B is in the range of 1.00 ≤ MC / MIL ≤ 3.00 relative to the modulus MIL of the inner liner 18. This provides the advantage of optimizing the relationship between the moduli MC and MIL.

[0277] Furthermore, in this tire 1, the innermost belt ply 14 (in Figure 8 In the case of the inner diameter side cross belt 141), the modulus MB [MPa] of the coated rubber 14br is in the range of 1.10 ≤ MB / MC ≤ 2.40 relative to the modulus MC of the coated rubber 13cr of the carcass ply 13A and 13B. Therefore, it has the advantage of optimizing the relationship between the moduli MB and MC.

[0278] Furthermore, in this tire 1, the modulus MC [MPa] of the coating rubber 13cr of the carcass plies 13A and 13B is in the range of 4.5 ≤ MC ≤ 12.0. This provides the advantage of optimized modulus MC.

[0279] Furthermore, in this tire 1, the thickness TC [mm] of the carcass ply layers 13A and 13B (see...) Figure 8The product of the loss tangent tanδ of the tire carcass ply 13A and 13B and the coated rubber 13cr at 60°C is within the range of 0.08 ≤ TC × tanδ ≤ 0.45. Therefore, it has the advantage of optimizing the thickness TC of the tire carcass ply 13A and 13B.

[0280] Furthermore, in this tire 1, the belt layer 14 is an organic fiber cord (belt cord 14bc) wrapped with coated rubber 14cr. See also Figure 8 It is made of multiple layers of belted fabric, 141-145 layers stacked together (see...). Figure 1 Furthermore, the outermost carcass ply 13B of the carcass layer 13 and the innermost belt ply of the belt layer 14 (in Figure 8 In this context, the peel force Hpp [N / 25mm] per 25mm width of the inner diameter side cross belt 141 is within the range of 90 ≤ Hpp / TCB ≤ 300 relative to the distance TCB [mm] from the outer diameter center of the carcass cord 13cc of the carcass ply 13B to the outer diameter center of the belt cord 14bc of the belt ply 141. This provides the advantage of ensuring tire durability.

[0281] Furthermore, in this tire 1, the two carcass plies 13A and 13B each have a main body portion 131 extending along the inner surface of the tire and an up-wound portion 132 that is rolled up to the outer side of the tire width direction and extends radially along the tire in a manner that wraps around the bead core 11 (see...). Figure 2 Furthermore, the radial height Hcs [mm] from the measuring point of the rim diameter RD to the end of the upper rolled portion 132 of the carcass ply 13 is defined. At this time, at least one carcass ply (in Figure 2 In the middle section, the radial height Hcs [mm] of the upper rolled portion 132 of the inner diameter sidewall carcass ply 13A) relative to the tire section height SH [mm] is in the range of 0.49 ≤ Hcs / SH ≤ 0.80 (see... Figure 2 Therefore, it has the advantage of optimizing the radial height Hcs of the upper rolled portion 132 of the carcass layer 13. Specifically, the lower limit mentioned above ensures the load capacity of the sidewall, and the upper limit mentioned above suppresses the decrease in rolling resistance caused by the increase in the mass of the carcass layer.

[0282] Furthermore, in this tire 1, the belt layer 14 is made of steel cords coated with rubber and has cord angles (θ41, θ42; see below) that are different from each other and are 15 degrees or more and 55 degrees or less relative to the tire circumference. Figure 3 A pair of cross-belts 141 and 142 stacked together (see...) Figure 1Furthermore, the breaking strength Tbt [N / 50mm] of each 50mm width of the pair of cross belts 141 and 142 is in the range of 25 ≤ Tbt / OD ≤ 250 relative to the tire outer diameter OD [mm]. Therefore, it has the advantage of being able to adequately ensure the load-bearing capacity of each pair of cross belts 141 and 142.

[0283] In addition, the tire 1 has a pair of bead cores 11, 11, a carcass layer 13 mounted on the bead cores 11, 11, and a belt layer 14 disposed radially outside the carcass layer 13 (see Figure 11 Furthermore, the tire outer diameter OD [mm] is in the range of 200 ≤ OD ≤ 660, and the total tire width SW [mm] is in the range of 100 ≤ SW ≤ 400. Furthermore, the carcass ply 13 is formed by laminating two carcass plies 13A' and 13B' made of organic fiber cords coated with coated rubber. Furthermore, the organic fiber cords of the two carcass plies 13A' and 13B' have cord angles that differ from each other and are in the range of 45 [deg] or more and 70 [deg] or less relative to the tire circumference. Furthermore, the breaking strength Tcs [N / 50mm] of each of the two carcass plies 13A and 13B per 50 [mm] width is in the range of 17 ≤ Tcs / OD ≤ 120 relative to the tire outer diameter OD [mm].

[0284] With this configuration, the load-bearing capacity of the carcass layer 13 can be adequately ensured in small-diameter tires, thus achieving the advantages of balancing tire wear resistance and low rolling resistance.

[0285] Example

[0286] Figures 12 to 14 This is a graph showing the results of performance tests on tires according to embodiments of the present invention.

[0287] Using this performance test, various test tires were evaluated for (1) low rolling resistance performance (fuel consumption), (2) wear resistance performance, and (3) load durability performance. Furthermore, as an example of a small-diameter tire, two test tire sizes were used. Specifically, test tire [A] with a tire size of 235 / 45R10 was mounted on a rim with a rim size of 10×8, and test tire [B] with a tire size of 145 / 80R12 was mounted on a rim with a rim size of 12×4.00B.

[0288] In the evaluation related to low rolling resistance performance (1), the test tire of [A] above was subjected to an internal pressure of 230 kPa and a load of 4.2 kN, and the test tire of [B] above was subjected to an internal pressure of 80% of the JATMA specified internal pressure and a load of 80% of the JATMA specified load. In addition, a four-wheel low-floor vehicle with the test tires mounted on all wheels was driven 50 times at a speed of 100 km / h on a test track with a total length of 2 km. After that, the fuel consumption rate [km / l] was calculated and evaluated. This evaluation was carried out by an index evaluation based on a comparative example (100). The larger the value, the smaller the fuel consumption rate, the greater the tendency to reduce rolling resistance, and the more preferred.

[0289] In the evaluation of wear resistance performance (2), the test tire of [A] above was subjected to an internal pressure of 230 kPa and a load of 4.2 kN, and the test tire of [B] above was subjected to an internal pressure of 80% of the JATMA specified internal pressure and a load of 80% of the JATMA specified load. In addition, a four-wheel low-floor vehicle with the test tires mounted on all wheels was driven for 10,000 km on a dry test track. Afterwards, the wear amount and degree of uneven wear of each tire were measured and evaluated. This evaluation was carried out by an index evaluation based on a comparative example (100), with a higher value indicating better performance.

[0290] In the durability performance evaluation (3), an indoor roller testing machine with a roller diameter of 1707 mm was used. The test tire of [A] was subjected to an internal pressure of 230 kPa and a load of 4.2 kN, and the test tire of [B] was subjected to an internal pressure of 80% of the JATMA specified internal pressure and a load of 88% of the JATMA specified load. Then, at a driving speed of 81 km / h, the load was increased by 13% every 2 hours, and the driving distance before the tire failure was measured. Then, based on the measurement results, an index evaluation (100) was performed with the comparative example as the benchmark. The larger the value of this evaluation, the better the product.

[0291] The test tire in the embodiment has Figure 1 The described structure includes a pair of bead cores 11, 11; a carcass layer 13 composed of a pair of carcass ply layers 13A, 13B; a belt layer 14 composed of a pair of cross belts 141, 142; a belt cover layer 143; a pair of belt edge cover layers 144, 144; and an additional belt 145; a tread rubber 15; a sidewall rubber 16; and a rim cushioning rubber 17. Furthermore, the carcass cord angle of the carcass layer 13 (not shown) is 90 degrees, and the angle of each belt ply of the belt layer 14 (see [reference needed])... Figure 3) are θ41=20[deg], θ42=-20[deg], θ43=θ44=0 [deg], θ45=20 [deg].

[0292] Regarding the test tire of the comparative example, in the test tire of Example 1, the tire outer diameter OD=531[mm], the tire total width SW=143[mm], the tire ground contact width TW=123[mm], and it was assembled on a rim with a rim size of 12.

[0293] As the test results show, the test tires in the embodiment take into account the tire's low rolling resistance, wear resistance and durability.

[0294] Symbol Explanation

[0295] 1: Tires

[0296] 10: Wheel rim

[0297] 11: Tire bead core

[0298] 12: Tire sidewall core

[0299] 13: Fetal layer

[0300] 131: Main Body

[0301] 132: Volume 1

[0302] 13cc: Tire cord

[0303] 13cr: Coated rubber

[0304] 14: Belt layer

[0305] 141, 142: Cross-belt bundles

[0306] 143: Belt Covering Layer

[0307] 144: Belt edge cover layer

[0308] 145: Additional belt

[0309] 14bc: With cord binding

[0310] 14Cr: Coated rubber

[0311] 15: Tread rubber

[0312] 151: Crown tread

[0313] 152: Base tread

[0314] 16: Sidewall Rubber

[0315] 17: Rim cushioning rubber

[0316] 18: Lining

[0317] 21-23: Circumferential main channel

Claims

1. A tire, the tire comprising a pair of bead cores, a carcass layer mounted on the bead cores, and a belt layer disposed radially outward of the carcass layer, characterized in that, The tire outer diameter OD (mm) is in the range of 200≤OD≤660, the tire total width SW (mm) is in the range of 100≤SW≤400, the carcass layer is made of two layers of carcass ply made of coated rubber-coated organic fiber cords, the organic fiber cords of the two carcass ply have a cord angle in the range of 80 (deg) or more and 100 (deg) relative to the tire circumference, and the breaking strength Tcs (N / 50mm) of each 50 (mm) width of the two carcass ply is in the range of 17≤Tcs / OD≤120 relative to the tire outer diameter OD (mm). When A1min=-0.0017, A2min=0.9, A3min=130, A1max=-0.0019, A2max=1.4, and A3max=400, the tire outer diameter OD and the tire total width SW satisfy the conditions of the following formula (1). ， In the cross-sectional view along the tire's radial direction, the following are defined: the tire's maximum width position Ac; point Au on the side profile at the same radial position relative to the end of the innermost layer of the belt layer; the tire's radial distance Hu from the tire's maximum width position Ac to point Au; point Au' on the side profile at a radial position 70% of the distance Hu from the tire's maximum width position Ac; point Bc on the main body of the carcass layer at the same radial position relative to the tire's maximum width position Ac; and point Bu' on the main body of the carcass layer at a radial position 70% of the distance Hu from the tire's maximum width position Ac. The tire width direction distance ΔBu' (mm) from point Bc to point Bu' is within the range of 1.10 ≤ ΔBu' / ΔAu' ≤ 8.00 relative to the tire width direction distance ΔAu' (mm) from the tire's maximum width position Ac to point Au'.

2. The tire according to claim 1, wherein, The distance TL (mm) from the center of the organic fiber cord of the inner diameter side of the two carcass plies to the inner surface of the tire is in the range of 0.001 ≤ TL / OD ≤ 0.009 relative to the outer diameter OD (mm) of the tire.

3. The tire according to claim 1 or 2, wherein, The distance TCSU (mm) from the center of the organic fiber cord of the inner diameter side carcass ply to the outer surface of the inner diameter side carcass ply is in the range of 0.09 ≤ TCSU / TL ≤ 1.00 relative to the distance TL (mm) from the center of the organic fiber cord of the inner diameter side carcass ply to the inner surface of the tire.

4. The tire according to claim 1 or 2, wherein the tire comprises an inner liner made of rubber material and disposed on the inner surface of the tire cavity to cover the carcass layer, the belt layer being formed by stacking multiple layers of belt ply made of coated rubber-coated organic fiber material, and the modulus MC (MPa) of the coated rubber of the carcass ply at 100% elongation relative to the modulus MIL (MPa) of the inner liner at 100% elongation and the modulus MB (MPa) of the coated rubber of the innermost belt ply of the belt layer at 100% elongation is in the range of MIL≤MC≤MB.

5. The tire according to claim 4, wherein, The modulus MC (MPa) of the coated rubber of the carcass ply is in the range of 1.00 ≤ MC / MIL ≤ 3.00 relative to the modulus MIL (MPa) of the liner.

6. The tire according to claim 4, wherein, The modulus MB (MPa) of the coated rubber of the innermost belt ply is in the range of 1.10 ≤ MB / MC ≤ 2.40 relative to the modulus MC (MPa) of the coated rubber of the carcass ply.

7. The tire according to claim 4, wherein, The modulus MC (MPa) of the coated rubber of the carcass ply is in the range of 4.5 ≤ MC ≤ 12.

0.

8. The tire according to claim 1 or 2, wherein, The product of the thickness TC (mm) of the carcass ply and the loss tangent tanδ of the coating rubber of the carcass ply at 60 (°C) is in the range of 0.08 ≤ TC × tanδ ≤ 0.

45.

9. The tire according to claim 1 or 2, wherein, The belt layer is formed by stacking multiple belt ply layers made of organic fiber cords coated with rubber. Furthermore, the peel force Hpp (N / 25mm) per 25mm width between the outermost carcass ply layer of the carcass layer and the innermost belt ply layer of the belt layer is in the range of 90≤Hpp / TCB≤300 relative to the distance TCB (mm) from the outer diameter center of the carcass cord of the carcass ply layer to the outer diameter center of the belt cord of the belt ply layer.

10. The tire according to claim 1 or 2, wherein, Each of the two carcass plies has a main body extending along the inner surface of the tire and an upper roll portion that is rolled up to the outer side of the tire width direction and extends radially along the tire in a manner that wraps around the bead core. The radial height Hcs (mm) from the measuring point of the rim diameter RD to the end of the upper roll portion is defined, and the radial height Hcs (mm) of the upper roll portion of at least one carcass ply is in the range of 0.49 ≤ Hcs / SH ≤ 0.80 relative to the tire section height SH (mm).

11. The tire according to claim 1 or 2, wherein, The belt layer is formed by stacking a pair of cross belts made of steel cord coated with coated rubber and having different signs and cord angles relative to the tire circumference of 15 degrees and 55 degrees. The breaking strength Tbt (N / 50mm) of each 50mm width of the pair of cross belts is in the range of 25≤Tbt / OD≤250 relative to the tire outer diameter OD (mm).

12. A tire comprising a pair of bead cores, a carcass layer mounted on the bead cores, and a belt layer disposed radially outward of the carcass layer, characterized in that, The tire outer diameter OD (mm) is in the range of 200≤OD≤660, and the total tire width SW (mm) is in the range of 100≤SW≤400. The carcass is composed of two layers of carcass ply made of coated rubber-coated organic fiber cords. The organic fiber cords of the two carcass ply have different signs and cord angles relative to the tire circumference in the range of 45 (deg) to 70 (deg). The breaking strength Tcs (N / 50mm) of each 50 (mm) width of the two carcass ply is in the range of 17≤Tcs / OD≤120 relative to the tire outer diameter OD (mm). When A1min=-0.0017, A2min=0.9, A3min=130, A1max=-0.0019, A2max=1.4, and A3max=400, the tire outer diameter OD and the tire total width SW satisfy the conditions of the following formula (1). ， In the cross-sectional view along the tire's radial direction, the following are defined: the tire's maximum width position Ac; point Au on the side profile at the same radial position relative to the end of the innermost layer of the belt layer; the tire's radial distance Hu from the tire's maximum width position Ac to point Au; point Au' on the side profile at a radial position 70% of the distance Hu from the tire's maximum width position Ac; point Bc on the main body of the carcass layer at the same radial position relative to the tire's maximum width position Ac; and point Bu' on the main body of the carcass layer at a radial position 70% of the distance Hu from the tire's maximum width position Ac. The tire width direction distance ΔBu' (mm) from point Bc to point Bu' is within the range of 1.10 ≤ ΔBu' / ΔAu' ≤ 8.00 relative to the tire width direction distance ΔAu' (mm) from the tire's maximum width position Ac to point Au'.

Images