Tire

Abstract

To provide a tire capable of suppressing poor appearance of a tire side part.SOLUTION: The tire 1 includes a pair of bead cores 11, 11, a carcass layer 13 stretched between the pair of bead cores 11, 11, and a tire side portion formed of a rubber member including a sidewall rubber 16. Additionally, the carcass layer 13 includes at least one carcass ply 131 that is turned up outward in the tire lateral direction so as to wrap around the pair of bead cores 11, 11. The tire side part includes a reference profile Pf formed by connecting a plurality of circular arcs having a center inside the tire, and a recessed part 4 recessed with respect to the reference profile Pf. Further, the recess portion 4 is arranged so as to cover the wound-up end portion 131e of at least one layer of the carcass ply 131 in the plan view of the tire side portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tire, and more particularly to a tire that can suppress poor appearance of the tire side portion. [Background technology]

[0002] In recent years, tires have adopted a structure in which the rubber gauge of the tire side portion is thinned in order to reduce the tire weight. A technology described in Patent Document 1 is known as a conventional tire adopting such a structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 05-193311 Summary of the Invention [Problem to be solved by the invention]

[0004] However, a structure in which the rubber gauge of the tire side portion is thinned has the problem that irregularities in the structure inside the tire can cause poor appearance (so-called light failure) in the tire side portion.

[0005] Therefore, the present invention has been made in view of the above, and has an object to provide a tire that can suppress poor appearance of the tire side portions. [Means for solving the problem]

[0006] In order to achieve the above object, the tire of the present invention is a tire comprising a pair of bead cores, a carcass layer spanning the pair of bead cores, and a tire side portion made of a rubber member including sidewall rubber, wherein the carcass layer includes at least one carcass ply wound back outward in the tire width direction so as to encase the pair of bead cores, and the tire side portion comprises a reference profile formed by connecting a plurality of arcs having a center inside the tire, and a recessed portion that is recessed relative to the reference profile, and the recessed portion is arranged to cover the turned-up end of the at least one carcass ply in a plan view of the tire side portion. [Effects of the Invention]

[0007] In the tire of this invention, the recess is positioned to cover the turned-up end of the carcass ply, which has the advantage of reducing residual air near the turned-up end of the carcass ply during the tire vulcanization molding process, thereby suppressing poor appearance of the tire side portion due to residual air. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view in the tire meridian direction showing a tire according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view showing a tire side portion of the tire shown in FIG. [Figure 3] FIG. 3 is an enlarged view showing the recessed portion in the tire side portion shown in FIG. [Figure 4] FIG. 4 is a plan view showing the tire side portion shown in FIG. [Figure 5] FIG. 5 is an explanatory view showing a modified example of the recess shown in FIG. [Figure 6] FIG. 6 is an explanatory diagram showing a modified example of the recess shown in FIG. [Figure 7] FIG. 7 is a table showing the results of performance tests on the tire according to the embodiment of the present invention. [Figure 8]FIG. 8 is a table showing the results of performance tests on the tire according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the components of these embodiments include those that can be substituted and are obvious substitutes while maintaining the identity of the invention. Furthermore, the multiple modifications described in these embodiments can be arbitrarily combined within the scope obvious to those skilled in the art.

[0010] [tire] 1 is a cross-sectional view in the tire meridian direction showing a tire 1 according to an embodiment of the present invention. The figure shows a cross-sectional view of one side region in the tire radial direction. In this embodiment, a pneumatic radial tire for passenger cars will be described as an example of a tire.

[0011] In the figure, the tire meridian cross section is defined as a cross section of the tire cut by a plane including the tire rotation axis (not shown). The tire equatorial plane CL is defined as a plane that passes through the midpoint of the tire section width defined by JATMA and is perpendicular to the tire rotation axis. The tire width direction is defined as the direction parallel to the tire rotation axis, and the tire radial direction is defined as the direction perpendicular to the tire rotation axis. Point T is the tire contact edge, and point A is the tire's maximum width position.

[0012] The tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair of rim cushion rubbers 17, 17 (see Figure 1).

[0013] The pair of bead cores 11, 11 are formed by winding one or more steel bead wires in an annular and multiple pattern and are embedded in the bead portions to form the cores of the left and right bead portions. The pair of bead fillers 12, 12 are disposed on the outer periphery of the pair of bead cores 11, 11 in the tire radial direction, respectively, to reinforce the bead portions.

[0014] The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies 131, 132 stacked together, and is toroidally laid between the left and right bead cores 11, 11 to form the tire framework. At least one carcass ply 131 is wrapped around and secured to the outside in the tire width direction so as to envelop the bead cores 11 and the bead fillers 12. The carcass plies 131, 132 are formed by coating multiple carcass cords made of steel or organic fiber material (e.g., aramid, nylon, polyester, rayon, etc.) with coating rubber and rolling them, and have a cord angle (defined as the inclination angle of the carcass cords in the longitudinal direction with respect to the tire circumferential direction) of 80 degrees or more and 100 degrees or less.

[0015] 1, for example, the carcass layer 13 has a two-layer structure formed by laminating first and second carcass plies 131 and 132. The first carcass ply 131 is wound back and secured to the outside in the tire width direction so as to encase the bead core 11 and the bead filler 12. The second carcass ply 132 has a so-called turndown structure and is disposed on the outer periphery of the first carcass ply 131 so as to cover the turned-up end 131e of the first carcass ply 131, and is disposed outside the bead core 11 and the bead filler 12 in the tire width direction.

[0016] However, this is not limited to this, and multiple carcass plies may be wrapped around the bead core 11 and bead filler 12 and secured to the outside in the tire width direction, or the second carcass ply 132 having a turndown structure may be omitted (not shown).

[0017] The belt layer 14 is formed by laminating a plurality of belt plies 141 to 144, and is disposed by being wound around the outer periphery of the carcass layer 13. The belt plies 141 to 144 include a pair of cross belts 141, 142, a belt cover 143, and a pair of belt edge covers 144, 144.

[0018] The pair of cross belts 141, 142 are formed by coating a plurality of belt cords made of steel or organic fiber material with coating rubber and rolling them, and have a cord angle (defined as the inclination angle of the belt cords in the longitudinal direction with respect to the tire circumferential direction) of 15 degrees or more and 55 degrees or less in absolute value. The pair of cross belts 141, 142 have cord angles of opposite signs to each other, and are layered with the longitudinal directions of the belt cords crossing each other (so-called cross-ply structure). The pair of cross belts 141, 142 are layered and arranged on the outer side of the carcass layer 13 in the tire radial direction.

[0019] The belt cover 143 and the pair of belt edge covers 144, 144 are configured by covering belt cover cords made of steel or organic fiber material with coating rubber, and have a cord angle of 0 degrees or more and 10 degrees or less in absolute value. The belt cover 143 and the belt edge cover 144 are, for example, strip materials made by covering one or more belt cover cords with coating rubber, and are configured by spirally winding this strip material multiple times around the outer circumferential surfaces of the cross belts 141, 142 in the tire circumferential direction. The belt cover 143 is disposed to cover the entire area of ​​the cross belts 141, 142, and the pair of belt edge covers 144, 144 are disposed to cover the left and right edge portions of the cross belts 141, 142 from the outside in the tire radial direction.

[0020] The tread rubber 15 is disposed on the outer periphery of the carcass layer 13 and the belt layer 14 in the tire radial direction to form the tread portion of the tire 1. The tread rubber 15 is made of a rubber material with excellent ground contact characteristics and weather resistance, and is exposed over the entire outer periphery of the tire to form the tread surface. A pair of sidewall rubbers 16, 16 are disposed on the outer sides of the carcass layer 13 in the tire width direction to form left and right sidewall portions. A pair of rim cushion rubbers 17, 17 extend from the inner side in the tire radial direction of the left and right bead cores 11, 11 and the turned-up portions of the carcass layer 13 to the outer side in the tire width direction to form the rim fitting surface of the bead portion.

[0021] The loss tangent tanδ of the sidewall rubber 16 at 60°C is in the range of 0.005 to 0.20, preferably 0.005 to 0.10. This suppresses deterioration of load durability due to recesses 4 in the tire side portions, which will be described later. The rubber hardness Hs of the sidewall rubber 16 is in the range of 40 to 60, preferably 50 to 55. The modulus M [MPa] of the sidewall rubber 16 at 100% elongation is in the range of 1.0 to 3.0, preferably 1.0 to 2.0.

[0022] The loss tangent tanδ is measured using a viscoelasticity spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd. under the conditions of a temperature of 60°C, a shear strain of 10%, an amplitude of ±0.5%, and a frequency of 20Hz.

[0023] Rubber hardness Hs is measured at a temperature of 20°C in accordance with JIS K6253.

[0024] The modulus (breaking strength) is measured by a tensile test using a dumbbell-shaped test piece at a temperature of 20°C in accordance with JIS K6251 (using a No. 3 dumbbell).

[0025] [Depression on tire side] Fig. 2 is an enlarged view showing a tire side portion of the tire 1 shown in Fig. 1. The figure shows one side region of the tire 1 bounded by the tire equatorial plane CL. Fig. 3 is an enlarged view showing a recess 4 in the tire side portion shown in Fig. 2. Fig. 4 is a plan view showing the tire side portion shown in Fig. 2.

[0026] 2 and 3, the tire side portion of this tire 1 has a recessed portion 4. The recessed portion 4 is defined as a depression or groove that is recessed with respect to the reference profile Pf, that is, the profile that is the reference for tire design.

[0027] The reference profile Pf is a contour line that approximates the outer surface of the sidewall from the bead portion to the buttress portion in a cross-sectional view in the tire meridian direction, using multiple continuous arcs, and is measured excluding partial unevenness formed on the tire side (for example, surface finishes such as patterns, stampings such as letters, side blocks, rim protectors, mold split marks, etc.).

[0028] The tire profile is the outline of the tire in a cross section taken along the tire meridian, and is measured using a laser profiler, such as a tire profile measuring device (manufactured by Matsuo Corporation).

[0029] As shown in FIGS. 2 and 4, the recessed portion 4 is disposed so as to cover the turned-up end portion 131e of at least one carcass ply 131 in a plan view of the tire side portion.

[0030] In the above configuration, the recess 4 is disposed so as to cover the turned-up end 131e of the carcass ply 131, thereby reducing residual air near the turned-up end 131e of the carcass ply 131 during the tire vulcanization-molding process, thereby suppressing poor appearance of the tire side portion due to residual air (so-called light failure). Specifically, near the turned-up end 131e of the carcass ply 131, rubber flow tends to deteriorate during the tire vulcanization-molding process, resulting in residual air. This tendency is particularly pronounced in structures in which the rubber gauge of the tire side portion is thinned for the purpose of reducing tire weight. Therefore, the tire vulcanization-molding mold has a protrusion for forming the recess 4 of the tire 1, and this protrusion is disposed at the position of the turned-up end 131e of the carcass ply 131, thereby promoting rubber flow near the turned-up end 131e of the carcass ply 131 and reducing residual air.

[0031] For example, in the configuration of FIG. 2, as shown in FIG. 4, the recessed portion 4 extends continuously around the entire circumference of the tire side portion, covering the entire circumference of the turned-up end portion 131e of the carcass ply 131. Also, a single, band-shaped recessed portion 4 is arranged in a smooth area having a smooth surface and extends in the tire circumferential direction. This configuration is preferable because the recessed portion 4 effectively reduces residual air. However, the configuration is not limited to this. The tire side portion may have multiple recessed portions (not shown), and at least one of these recessed portions may be arranged to cover the turned-up end portion 131e of at least one layer of carcass ply 131 in a plan view of the tire side portion.

[0032] Also, it is preferable that the turned-up end 131e of the carcass ply 131 is disposed in the radial center of the recessed portion 4. Specifically, in Fig. 3, the radial height He from the radially inner edge of the recessed portion 4 to the turned-up end 131e of the carcass ply 131 is in the range of 0.25 ≦ He / H4 ≦ 0.75 with respect to the radial height H4 of the recessed portion 4, and preferably in the range of 0.30 ≦ He / H4 ≦ 0.70.

[0033] The radial heights He and H4 are measured as the distance in the radial direction of the tire when the tire is mounted on a specified rim, pressurized to a specified internal pressure, and in an unloaded state.

[0034] The specified rim refers to the "applicable rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressure" specified by ETRTO. The specified load refers to the "maximum load capacity" specified by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" specified by TRA, or the "load capacity" 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.

[0035] 2, the distance H31 from the rim diameter measurement point to the turned-up end 131e of at least one carcass ply 131 is in the range of 0.20≦H31 / SH≦0.60 relative to the tire cross-sectional height SH. Since residual air is likely to be generated in the region where the ratio H31 / SH is in the above range, by applying this structure to a tire, the recess 4 can effectively reduce residual air.

[0036] The tire section height SH is half the distance between the tire outer diameter and the rim diameter, and is measured with the tire mounted on a specified rim, with the specified internal pressure applied, and with no load applied.

[0037] In addition, it is preferable that the tire cross-sectional height SH is 100 [mm]≦SH.

[0038] 2, the first carcass ply 131 is wound around the entire bead core 11 and the bead filler 12 and is in self-contact with the main body portion 131m. Also, a turned-up end portion 131e of the first carcass ply 131 is located between the radially outer end portion of the bead filler 12 and the tire maximum width position A.

[0039] 2, the distance H4A from the rim diameter measurement point to the radially inner edge of the recessed portion 4 is in the range of 0.10≦H4A / SH relative to the tire cross-sectional height SH. It is also preferable that the radially inner edge of the recessed portion 4 is located radially outward of the rim check line (not shown). This suppresses interference between the recessed portion 4 and the rim flange.

[0040] Furthermore, it is preferable that the recess 4 is disposed so as to cover the radially outer end of the bead filler 12 in a plan view of the tire side portion (not shown). Specifically, the radially inner edge of the recess 4 is located radially inner in the tire direction than the radially outer edge of the bead filler 12. This reduces the amount of residual air near the edge of the bead filler 12, thereby suppressing poor appearance of the tire side portion due to residual air.

[0041] 2, the distance H4B from the rim diameter measurement point to the radially outer edge of the recessed portion 4 is in the range of H4B / SH≦0.70 relative to the tire cross-sectional height SH. The radially outer edge of the recessed portion 4 is located radially inward of the tire ground contact edge T and radially inward of the mold parting position M of the tire vulcanization mold. In the configuration of FIG. 2, the radially outer edge of the recessed portion 4 is located radially inward of the tire maximum width position A. Therefore, the recessed portion 4 does not intersect with the tire maximum width position A.

[0042] The distances H4A and H4B of the recessed portion 4 are measured as distances in the tire radial direction when the tire is mounted on a specified rim, a specified internal pressure is applied, and the tire is in an unloaded state.

[0043] 3, the radial height H4 of the recessed portion 4 relative to the tire cross-sectional height SH is in the range of 0.05≦H4 / SH≦0.20, and preferably in the range of 0.10≦H4 / SH≦0.18. The above lower limit ensures the radial height H4 of the recessed portion 4, ensuring the effect of the recessed portion 4 in reducing residual air. The above upper limit prevents a decrease in rigidity of the tire side portion caused by the recessed portion 4 being excessively large.

[0044] 3, the radial height He from the radially inner edge of the recess 4 to the turned-up end 131e of the carcass ply 131 is in the range of 0.25≦He / H4≦0.75, and preferably 0.30≦He / H4≦0.70, relative to the radial height H4 of the recess 4. Therefore, the turned-up end 131e of the carcass ply 131 is positioned in the center of the recess 4. This improves the effect of the recess 4 in reducing residual air.

[0045] 3, the distance T1 from the turned-up end 131e of the carcass ply 131 to the bottom of the recess 4, relative to the distance T2 from the turned-up end 131e to the reference profile Pf, is in the range of T1 / T2≦0.80, and preferably T1 / T2≦0.60. This ensures the depth of the recess 4 at the turned-up end 131e of the carcass ply 131 (dimension symbol omitted in the figure: corresponds to the difference T2−T1), ensuring the effect of the recess 4 in reducing residual air. There is no particular lower limit for the ratio T1 / T2, but it is constrained by the lower limit of the rubber gauge T1, which will be described later.

[0046] The distance T1 from the turned-up end 131e to the bottom surface of the recess 4 is measured as the thickness of the sidewall rubber 16 on a perpendicular line (see FIG. 3; reference numerals are omitted in the figure) drawn from the turned-up end 131e to the reference profile Pf. Therefore, the distance T1 is measured excluding the coating rubber of the carcass plies 131, 132.

[0047] The distance T2 from the turned-up end 131e to the reference profile Pf is measured as the reference thickness of the sidewall rubber 16 on a perpendicular line (see FIG. 3; reference numerals are omitted in the figure) drawn from the turned-up end 131e to the reference profile Pf, i.e., the thickness of the sidewall rubber 16 in the absence of the recess 4. Therefore, the distance T1 is measured excluding the coating rubber of the carcass plies 131, 132.

[0048] 3, the distance T1 from the turned-up end 131e of the carcass ply 131 to the bottom surface of the recess 4 is in the range of 1.0 mm ≦ T1, and preferably in the range of 1.5 mm ≦ T1. This ensures the thickness of the sidewall rubber 16 and prevents the carcass layer 13 from being exposed. There is no particular upper limit to the distance T1, but it is restricted by the ratio T1 / T2. From the perspective of reducing the tire weight, it is preferable that the distance T1 be in the range of T1 ≦ 2.0 mm.

[0049] 3, the distance T2 from the turned-up end 131e of the carcass ply 131 to the reference profile Pf is in the range of 2.5 mm≦T2≦3.5 mm, and preferably in the range of 2.5 mm≦T2≦3.0 mm. The lower limit ensures durability of the tire sidewalls, and the upper limit prevents deterioration of rolling resistance due to an increase in tire weight.

[0050] [Variations] Figures 5 and 6 are explanatory diagrams showing modified examples of the recess 4 shown in Figure 3. In these figures, the same components as those shown in Figure 3 are given the same reference numerals, and their description will be omitted.

[0051] In the configuration shown in FIG. 3, the recess 4 has an inner surface (reference numeral omitted in the drawing) formed by connecting a flat bottom surface and a pair of side surfaces in a cross section taken along the tire meridian direction. The flat bottom surface is disposed to cover the turned-up end portion 131e of the carcass ply 131. The flat bottom surface has a flat surface without any irregularities and is preferably disposed parallel to the main body portion 131m of the carcass ply 131. The radial height H43 of the flat bottom surface, relative to the radial height H4 of the recess 4, is in the range of 0.20≦H43 / H4≦0.80, preferably 0.30≦H4 / H4≦0.70. The lower limit ensures the radial height H43 of the flat bottom surface, improving the effect of the recess 4 in reducing residual air. The upper limit ensures the connection angle between the flat bottom surface and the pair of side surfaces, suppressing the occurrence of cracks at the connection between them.

[0052] In the configuration shown in FIG. 3, the connection between the flat bottom surface of the recessed portion 4 and the pair of side surfaces, as well as the connection between the recessed portion 4 and the reference profile Pf, have an R-shape in cross section in the tire meridian direction. That is, each connection is R-chamfered. This promotes the flow of rubber to the inner surface of the recessed portion 4 during tire vulcanization, improving the effect of the recessed portion 4 in reducing residual air. Furthermore, the occurrence of cracks originating from these connection points is suppressed. Furthermore, the radius of curvature of the R-shape is preferably in the range of 5 mm to 50 mm.

[0053] In contrast, in the configuration shown in Fig. 5, the recess 4 has a V-shaped inner surface in a cross section taken along the tire meridian. Therefore, the radial height H43 of the flat bottom surface described above is 0. In this case, it is preferable that the position where the depth of the recess 4 (dimension symbols omitted in the drawing) is at its maximum, i.e., the radial distance Dc between the apex of the V-shape and the turned-up end 131e of the carcass ply 131, is in the range of -0.10 ≤ Dc / SH ≤ 0.10 relative to the tire cross-sectional height SH. This ensures that the recess 4 effectively reduces residual air.

[0054] 6, the recess 4 has a rectangular inner surface in a cross section taken along the tire meridian. Therefore, the radial height H43 of the flat bottom surface is set large. Even with this configuration, the recess 4 can still reduce residual air.

[0055] 3, the recess 4 has the flat bottom surface described above. This configuration is preferable because the recess 4 can effectively reduce residual air. However, this is not limiting, and the recess 4 may have an uneven portion on the bottom surface (not shown). Even with this configuration, the recess 4 can still reduce residual air.

[0056] [effect] As described above, [1] the tire 1 includes a pair of bead cores 11, 11, a carcass layer 13 spanning the pair of bead cores 11, 11, and a tire side portion made of a rubber member including a sidewall rubber 16 (see FIG. 2). The carcass layer 13 includes at least one carcass ply 131 wound back toward the outside in the tire width direction so as to encase the pair of bead cores 11, 11 (see FIG. 2). The tire side portion includes a reference profile Pf formed by connecting multiple arcs having a center inside the tire, and a recessed portion 4 recessed relative to the reference profile Pf. The recessed portion 4 is disposed to cover a turned-up end portion 131e of at least one carcass ply 131 in a plan view of the tire side portion (see FIGS. 2 to 4).

[0057] In the above configuration, the recess 4 is positioned to cover the turned-up end 131e of the carcass ply 131, which has the advantage of reducing residual air near the turned-up end 131e of the carcass ply 131 during the tire vulcanization molding process, thereby suppressing poor appearance of the tire side portion due to residual air.

[0058] [2] In the tire 1 described in [1] above, the radial height He (see FIG. 3) from the radially inner edge of the recess 4 to the turned-up end 131e of at least one carcass ply 131 is in the range of 0.25≦He / H4≦0.75 relative to the radial height H4 of the recess 4. This has the advantage of improving the effect of the recess 4 in reducing residual air.

[0059] [3] In the tire 1 described in [1] or [2] above, the distance T1 (see FIG. 3) from the turned-up end 131e of at least one carcass ply 131 to the bottom of the recess 4 is in the range of T1 / T2≦0.80, where T2 is the distance from the turned-up end 131e to the reference profile Pf. This ensures the depth of the recess 4 at the turned-up end 131e of the carcass ply 131 (dimension symbol omitted in the drawing: corresponds to the difference T2−T1), which has the advantage of ensuring the effect of reducing residual air by the recess 4.

[0060] [4] In the tire 1 described in [3] above, the distance T1 (see FIG. 3) from the turned-up end 131e of at least one carcass ply 13 to the bottom surface of the recess 4 is in the range of 1.0 mm≦T1. This ensures the thickness of the sidewall rubber 16, which has the advantage of ensuring the durability of the tire sidewall.

[0061] [5] In the tire 1 described in [3] above, the distance T2 (see FIG. 3) from the turned-up end 131e of at least one carcass ply 131 to the reference profile Pf is in the range of 2.5 mm≦T2≦3.5 mm. The lower limit ensures durability of the tire sidewall, and the upper limit has the advantage of suppressing deterioration in rolling resistance due to an increase in tire weight.

[0062] [6] In the tire 1, in the tire 1 described in any one of the above [1] to [5], the distance H31 from the measurement point of the rim diameter to the turned-up end 131e of at least one carcass ply 131 is in the range of 0.20≦H31 / SH≦0.60 with respect to the tire cross-sectional height SH (see FIG. 2). Since residual air is likely to be generated in the region where the ratio H31 / SH is in the above range, applying a tire with such a structure has the advantage that the residual air can be effectively reduced by the recess 4.

[0063] [7] In the tire 1, in the tire 1 described in any one of the above [1] to [6], the radial height H4 of the recessed portion 4 (see FIG. 3) is in the range of 0.05≦H4 / SH≦0.20 relative to the tire cross-sectional height SH (see FIG. 2). The above lower limit ensures the radial height H4 of the recessed portion 4, and ensures the effect of the recessed portion 4 in reducing residual air. The above upper limit has the advantage of suppressing a decrease in rigidity of the tire side portion caused by the recessed portion 4 being excessively large.

[0064] [8] In the tire 1, in the tire 1 described in any one of [1] to [7] above, the recessed portion 4 has an inner surface shape (reference numerals omitted in the drawing: see FIG. 3) formed by connecting a flat bottom surface and a pair of side surfaces in a cross section seen in the tire meridian direction. The radial height H43 of the flat bottom surface is in the range of 0.20≦H43 / H4≦0.80 relative to the radial height H4 of the recessed portion 4. The lower limit ensures the radial height H43 of the flat bottom surface, improving the effect of the recessed portion 4 in reducing residual air. The upper limit ensures the connecting angle between the flat bottom surface and the pair of side surfaces, advantageously suppressing the occurrence of cracks at the connecting portions.

[0065] [9] In the tire 1 according to any one of the above [1] to [8], the connection portion between the flat bottom surface and the pair of side surfaces and the connection portion between the recessed portion 4 and the reference profile Pf have an R-shape in a cross section viewed in the tire meridian direction. This has the advantage of promoting the flow of rubber to the inner surface of the recessed portion 4 during vulcanization molding of the tire, thereby improving the effect of the recessed portion 4 in reducing residual air.

[0066]

[10] In the tire 1 according to any one of the above [1] to [9], the loss tangent tanδ of the sidewall rubber 16 (see FIG. 2) at 60°C is 0.10 or less, which has the advantage of suppressing deterioration in load durability caused by the recessed portion 4 in the tire side portion.

[0067]

[11] In the tire 1 according to any one of the above items [1] to

[10] , the recessed portion 4 extends continuously around the entire circumference of the tire side portion (see FIG. 4). This has the advantage that the effect of the recessed portion 4 in reducing residual air is properly ensured.

[0068]

[12] In the tire 1 according to any one of the above items [1] to

[11] , a single, band-shaped recess 4 is arranged in a smooth region having a smooth surface and extends in the tire circumferential direction (see FIGS. 2 and 4). This has the advantage that the recess 4 can effectively reduce residual air. [Example]

[0069] 7 and 8 are tables showing the results of performance tests of the tire according to the embodiment of the present invention.

[0070] In this performance test, several types of test tires were evaluated for (1) appearance performance and (2) durability performance. Test tires with a tire size of 235 / 60R18 107V were also prepared.

[0071] (1) In the evaluation of appearance performance, 1,000 test tires are produced, and the appearance defects of the tire sidewalls near the wrap-up end of the carcass layer are observed, and the incidence rate is calculated. In this evaluation, the smaller the numerical value, the lower the incidence rate of appearance defects, and therefore the more preferable it is.

[0072] (2) In the evaluation of durability performance, a test vehicle runs over a curb 110 mm high at a speed of 10 km / h and an approach angle of 30 degrees. Cracks (length and depth) in the sidewall of 1,000 tire samples are observed. Based on these observations, an index rating is then given, with the comparative example being assigned a standard rating of 100. The higher the rating, the better; a rating of 95 or higher indicates adequate performance.

[0073] 1 to 4, and includes a recess 4 disposed to cover a turned-up end 131e of a carcass ply 131 in a plan view of the tire side portion. The tire cross-sectional height SH is 137 mm.

[0074] The test tire of the comparative example is the test tire of Example 1, but does not have the recessed portion 4 in the tire side portion, and has a tire side surface that follows the reference profile Pr.

[0075] As the test results show, it is clear that the test tires of the examples can improve the appearance performance of the tire while maintaining the durability performance of the tire. [Explanation of symbols]

[0076] 1 tire; 4 recess; 11 bead core; 12 bead filler; 13 carcass layer; 131, 132 carcass ply; 131m main body; 131e turned-up end; 14 belt layer; 141, 142 cross belt; 143 belt cover; 144 belt edge cover; 15 tread rubber; 16 sidewall rubber; 17 rim cushion rubber; Pr reference profile

Claims

1. A tire comprising a pair of bead cores, a carcass layer spanning the pair of bead cores, and a tire side portion made of a rubber member including a sidewall rubber, the carcass layer includes at least one carcass ply wound back on the outer side in the tire width direction so as to enclose the pair of bead cores, The tire side portion has a reference profile formed by connecting a plurality of arcs having a center inside the tire, and a recessed portion that is recessed relative to the reference profile, and A tire characterized in that the recess is arranged to cover a turned-up end portion of the at least one carcass ply in a plan view of the tire side portion.

2. 2. The tire according to claim 1, wherein a radial height He from a radially inner edge portion of the recess to the turned-up end portion of the at least one carcass ply is in a range of 0.25≦He / H4≦0.75, relative to a radial height H4 of the recess.

3. 2. The tire according to claim 1, wherein a distance T1 from the turned-up end of the at least one carcass ply to a bottom surface of the recess is in a range of T1 / T2≦0.80, relative to a distance T2 from the turned-up end to the reference profile.

4. The tire according to claim 3, wherein a distance T1 from the turned-up end of the at least one carcass ply to a bottom surface of the recess is in a range of 1.0 mm≦T1.

5. The tire according to claim 3, wherein a distance T2 from the turned-up end of the at least one carcass ply to the reference profile is in a range of 2.5 mm≦T2≦3.5 mm.

6. 2. The tire according to claim 1, wherein a distance H31 from a measurement point of the rim diameter to the turned-up end of the at least one carcass ply is in a range of 0.20≦H31 / SH≦0.60 relative to a tire section height SH.

7. The tire according to claim 1, wherein a radial height H4 of the recessed portion and a tire cross-sectional height SH are in a range of 0.05≦H4 / SH≦0.

20.

8. 2. The tire according to claim 1, wherein the recess has an inner surface shape formed by connecting a flat bottom surface and a pair of side surfaces in a cross section seen in the tire meridian direction, and a radial height H43 of the flat bottom surface relative to a radial height H4 of the recess is in a range of 0.20≦H43 / H4≦0.

80.

9. The tire according to claim 8 , wherein a connection portion between the flat bottom surface and the pair of side surfaces, and a connection portion between the recessed portion and the reference profile, have an R-shape when viewed in a cross section in the tire meridian direction.

10. 2. The tire according to claim 1, wherein the sidewall rubber has a loss tangent tanδ at 60° C. of 0.10 or less.

11. The tire according to claim 1 , wherein the recessed portion extends continuously around the entire circumference of the tire side portion.

12. The tire according to claim 11, wherein the single band-shaped recess is arranged in a smooth region having a smooth surface and extends in the tire circumferential direction.

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