tire

Abstract

This tire comprises, on a tire side surface, a ridge region 5 formed by arranging a plurality of ridge units U (UA to UD). Each of the plurality of ridge units U includes, in plan view of the tire side surface, a first ridge 52 having an annular structure, and a second ridge 53 having a linear structure and extending along an inner periphery of the first ridge 52. The first ridge 52 is formed by connecting two or more annular projecting parts 521a-521c projecting radially from a ridge center and at least one of annular recessed parts 522a-522c which are recessed toward the ridge center.

Description

tire

[0001] The present invention relates to a tire, and more particularly to a tire that can improve the blackening performance and visual angle uniformity performance of a ridge region.

[0002] Recent tires have adopted a configuration in which a ridge region consisting of multiple ridges is used to blacken markings such as side brands, thereby improving their visibility. A known conventional tire employing such a configuration is the technology described in Patent Document 1. However, there is also the issue of making the blackening effect of the ridge region uniform when the tire side surface is viewed from different directions. A known conventional tire addressing this issue is the technology described in Patent Document 2.

[0003] European Patent Application Publication No. 3030432 Japanese Patent Application Laid-Open No. 2016-215700

[0004] An object of the present invention is to provide a tire that can improve the blackening performance and the visual angle uniformity performance of the ridge region.

[0005] In order to achieve the above-mentioned object, the tire of the present invention is a tire having a ridge region on the tire side surface which is composed of an arrangement of a plurality of ridge units, and each of the plurality of ridge units is characterized in that, in a plan view of the tire side surface, it has a first ridge having a ring-shaped structure and a second ridge having a linear structure and extending along the inner circumference of the first ridge.

[0006] In the tire according to the present invention, (1) the tire side surface includes a ridge region formed by an array of multiple ridge units, so that in a plan view of the tire side portion, the light absorption rate in the ridge region is relatively higher than that in other regions. This makes the ridge region relatively dark, creating a clear contrast on the tire side surface. Furthermore, (2) the second ridge extends along the inner circumference of the curved first ridge, promoting the light absorption rate and diffuse reflection between the first ridge and the second ridge. These advantages result in improved visibility of the tire side surface.

[0007] FIG. 1 is a cross-sectional view in the tire meridian direction showing a tire according to an embodiment of the present invention. FIG. 2 is a plan view showing a tire side portion of the tire shown in FIG. 1. FIG. 3 is an enlarged view showing a marking portion of the tire side portion shown in FIG. 2. FIG. 4 is an explanatory diagram showing a ridge region of the tire side portion shown in FIG. 2. FIG. 5 is an explanatory diagram showing a ridge region of the tire side portion shown in FIG. 2. FIG. 6 is an explanatory diagram showing a ridge region of the tire side portion shown in FIG. 2. FIG. 7 is an explanatory diagram showing a ridge region of the tire side portion shown in FIG. 2. FIG. 8 is an explanatory diagram showing a modified example of the ridge region shown in FIG. 5. FIG. 9 is an explanatory diagram showing a modified example of the ridge region shown in FIG. 5. FIG. 10 is an explanatory diagram showing a modified example of the ridge region shown in FIG. 5. FIG. 11 is an explanatory diagram showing a modified example of the ridge region shown in FIG. 5. FIG. 12 is an explanatory diagram showing a modified example of the ridge region shown in FIG. 5. FIG. 13 is an explanatory diagram showing a modified example of the ridge region shown in FIG. 5. FIG. 14 is an explanatory diagram showing a modified example of the ridge region shown in FIG. 5. Fig. 15 is an explanatory diagram showing a modified example of the ridge region shown in Fig. 5. Fig. 16 is an explanatory diagram showing a modified example of the ridge region shown in Fig. 5. Fig. 17 is an explanatory diagram showing a modified example of the ridge region shown in Fig. 5. Fig. 18 is an explanatory diagram showing a modified example of the ridge region shown in Fig. 2. Fig. 19 is a table showing the results of performance tests on tires according to embodiments of the present invention.

[0008] 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.

[0009] [Tire] Fig. 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 of the tire 1 mounted on a rim 20. In this embodiment, a pneumatic radial tire for passenger cars will be described as an example of a tire.

[0010] 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 a direction parallel to the tire rotation axis, and the tire radial direction is defined as a direction perpendicular to the tire rotation axis. Point T is the tire ground contact edge, and point Ac is the tire's maximum width position.

[0011] 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).

[0012] The pair of bead cores 11, 11 are formed by winding one or more steel bead wires in an annular and multiple manner, 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 peripheries of the pair of bead cores 11, 11 in the tire radial direction, respectively, to reinforce the bead portions.

[0013] The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies stacked together, and is toroidally laid between the left and right bead cores 11, 11 to form the tire framework. Both ends of the carcass layer 13 are wrapped around and secured to the outside in the tire width direction so as to enclose the bead cores 11 and the bead fillers 12. The carcass ply of the carcass layer 13 is 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 has 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.

[0014] The belt layer 14 is formed by laminating a plurality of belt plies 141 to 143, and is disposed by being wound around the outer periphery of the carcass layer 13. The belt plies 141 to 143 each include a pair of cross belts 141, 142 and a belt cover 143.

[0015] 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 belt cords' longitudinal directions crossing each other (a so-called cross-ply structure). The pair of cross belts 141, 142 are layered on the tire radially outer side of the carcass layer 13.

[0016] The belt cover 143 is formed by covering a belt cover cord made of steel or organic fiber material with coating rubber, and has a cord angle of 0 degrees or more and 10 degrees or less in absolute value. The belt cover 143 is, for example, a strip material formed by covering one or more belt cover cords with coating rubber, and is formed by winding this strip material spirally around the outer circumferential surfaces of the cross belts 141, 142 multiple times in the tire circumferential direction. The belt cover 143 is disposed to cover the entire area of ​​the cross belts 141, 142.

[0017] 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.

[0018] [Tire Side Portion] Fig. 2 is a plan view showing the tire side portion of the tire shown in Fig. 1. Fig. 3 is an enlarged view showing the marking portion 2 of the tire side portion shown in Fig. 2. In these figures, Fig. 2 shows a plan view of the tire 1 as seen from the axial direction, and Fig. 3 shows a part of the marking portion 2.

[0019] As shown in FIG. 2, the tire 1 includes a marking portion 2 and a peripheral region 3 on the tire side.

[0020] The marking portion 2 includes a mark consisting of letters, figures, symbols, or a combination thereof, and particularly includes a trademark that functions as an identification sign indicating the tire manufacturer, tire brand, etc. Furthermore, multiple marking portions 2, 2 are arranged spaced apart in the tire circumferential direction. For example, in the configuration shown in Fig. 2, a mark consisting of a combination of the character string "YOKOHAMA" indicating the tire manufacturer and a logo with a stylized "Y," the initial letter of the name, is stamped on the surface of the tire side. Furthermore, a pair of marking portions 2, 2 are arranged in opposing positions in the tire circumferential direction.

[0021] 3, the radial height H2 of the elements 2A to 2E constituting the marking portion 2 is in the range of 0.05≦H2 / SH≦0.80 relative to the tire cross-sectional height SH, and preferably in the range of 0.10≦H2 / SH≦0.70. This improves the visibility of the marking portion 2.

[0022] The radial height H2 of the elements 2A to 2E is measured as the maximum extension length of the elements 2A to 2E in the tire radial direction.

[0023] The tire section height SH is the distance half the difference between the tire outer diameter and the rim diameter, and is measured with the tire mounted on a specified rim, with a specified internal pressure applied, and in an unloaded state.

[0024] 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 pressures" 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.

[0025] The peripheral region 3 is an area surrounding the marking portion 2 and is formed on the surface of the tire side portion. The peripheral region 3 may be a smooth surface having a smooth surface, or may be an uneven surface that has been subjected to a surface treatment.

[0026] For example, in the configuration of Fig. 2, the peripheral region 3 is a smooth, continuous, smooth surface without grooves or unevenness. The peripheral region 3 is disposed to surround the entire marking portion 2, thereby enhancing the visibility of the marking portion 2. The peripheral region 3 is formed between a pair of narrow ribs 41, 42 extending in the tire circumferential direction, thereby enhancing the design of the tire side portion. The single peripheral region 3 has an annular structure extending around the entire circumference of the tire side portion, thereby surrounding the pair of marking portions 2, 2.

[0027] 2 , the marking portion 2 and the peripheral region 3 are disposed radially outward of the tire maximum width position Ac. More specifically, a pair of narrow ribs 41, 42 extending in the tire circumferential direction are disposed in the region from the tire ground contact edge T to the tire maximum width position Ac (see FIG. 1 ), and the marking portion 2 and the peripheral region 3 are disposed between these narrow ribs 41, 42. This improves the visibility of the marking portion 2. However, this is not limiting, and the marking portion 2 and the peripheral region 3 may be disposed so as to intersect with the tire maximum width position Ac or may be disposed radially inward of the tire maximum width position Ac (not shown).

[0028] The tire maximum width position Ac is defined as the maximum width position of the tire section width.

[0029] The tire cross-sectional width is measured as the straight-line distance between the sidewalls, excluding any patterns or letters on the side of the tire, when the tire is mounted on a specified rim, pressurized to a specified internal pressure, and under no load.

[0030] The tire ground contact edge T is defined as the widest position in the axial direction of the tire at the contact surface between the tire and a flat plate when the tire is mounted on a specified rim, pressurized to a specified internal pressure, and placed perpendicular to a flat plate in a stationary state and subjected to a load corresponding to a specified load.

[0031] The pair of thin ribs 41, 42 have a width of 0.4 mm to 0.8 mm and a height of 0.1 mm to 1.0 mm, and function as a path for discharging residual air during tire vulcanization. This prevents vulcanization defects from occurring in the marking portion 2 and the surrounding area 3. In the configuration shown in Figure 2, the thin rib 41 on the outer diameter side is located at the mold split position of the tire molding die.

[0032] 3, the radial height H2 [mm] of the elements 2A to 2E constituting the marking portion 2, relative to the arrangement interval H4 [mm] of the thin ribs 41, 42 in the tire radial direction, is in the range of 0.30≦H2 / H4≦0.80, and preferably in the range of 0.40≦H2 / H4≦0.70. Also, as shown in FIG. 3, it is preferable that the marking portion 2 is arranged at a distance from the pair of thin ribs 41, 42. This improves the visibility of the marking portion 2.

[0033] [Ridge Region] Figures 4 to 7 are explanatory diagrams showing the ridge region 5 of the tire side portion shown in Figure 2. In these figures, Figure 4 shows one element 2A constituting the marking portion 2 shown in Figure 3, Figure 5 is an enlarged plan view showing a portion of the ridge region 5 shown in Figure 4, Figure 6 is an enlarged view showing a single ridge unit U (UA to UD) shown in Figure 5, and Figure 7 is a cross-sectional view taken along line A showing the ridge unit U shown in Figure 6. Here, as an example, a configuration in which the marking portion 2 is made up of the ridge region 5 will be described.

[0034] As shown in FIG. 7, the ridge region 5 is made up of a housing 51 and first and second ridges 52 and 53 .

[0035] The housing 51 is a frame-shaped recess formed in the tire side surface, and in a plan view of the tire side, forms the outline of the marking portion 2. The depth H51 of the housing 51 (see FIG. 7) is in the range of 0.10 mm≦H51≦3.00 mm, and preferably in the range of 0.20 mm≦H51≦1.50 mm.

[0036] The depth H51 of the housing 51 is defined as the distance from the edge of the housing 51 (the surface of the peripheral region 3 in FIG. 7) to the bottom surface of the housing 51.

[0037] As shown in Fig. 7, the first and second ridges 52, 53 are rib-like convex portions that protrude from the bottom surface of the housing 51 and have a cross-sectional shape that narrows toward the top. Also, as shown in Fig. 5, a plurality of ridge units U each consisting of the first and second ridges 52, 53 are arranged in a predetermined direction and filled into the housing 51. The planar shape and arrangement pattern of the ridge units U will be described in detail later.

[0038] For example, in the configuration of FIG. 3, the marking portion 2 is formed by a ridge region 5 as shown in FIG. 4. Specifically, the logo 2A constituting the marking portion 2 is composed of a combination of multiple thin lines arranged in parallel. The outlines of these thin lines are formed by the edges of the housing 51 (see FIG. 7), which will be described later. Similarly, other components constituting the marking portion 2 (e.g., elements 2B to 2E in FIG. 3) are composed of thick lines representing letters, and the outlines of the thick lines are formed by the edges of the housing 51 (not shown). Also, as shown in FIG. 7, the first and second ridges 52 and 53 have uniform trapezoidal or triangular cross sections. A plurality of ridge units U, each consisting of the first and second ridges 52 and 53, are arranged in a predetermined arrangement pattern within the housing 51, filling the entire area of ​​the housing 51. As a result, the marking portion 2 is represented by the housing 51 and the ridge units U.

[0039] In the above configuration, the tire side surface includes a ridge region 5 formed by an arrangement of multiple ridge units U, and therefore, in a plan view of the tire side portion, the light absorption rate in the ridge region 5 (marking portion 2 in FIG. 3 ) is relatively higher than the light absorption rate in other regions (peripheral region 3 in FIG. 3 ). This makes the ridge region 5 relatively black, providing a clear contrast to the tire side surface and improving the visibility of the tire side surface.

[0040] 7 , the heights H52 and H53 of the first and second ridges 52 and 53, relative to the depth H51 of the housing 51, are within the ranges of 0.30≦H52 / H51<1.00 and 0.30≦H53 / H51<1.00, and preferably within the ranges of 0.50≦H52 / H51≦0.95 and 0.50≦H53 / H51≦0.95. Therefore, the tops of the first and second ridges 52 and 53 are embedded within the housing 51. This configuration is preferable in that it suppresses deterioration of the air resistance of the tire side portion due to the ridges 52 and 53 protruding from the tire side surface. However, the present invention is not limited to this configuration, and the ridges 52, 53 may protrude from the tire side surface (not shown) by having the heights H52, H53 of the ridges 52, 53 be within the ranges of 1.00≦H52 / H51 and 1.00≦H53 / H51 relative to the depth H51 of the housing 51. In this configuration, when wax is applied to the tire side surface, the wax is more easily applied to the tops of the ridges 52, 53, improving the retention of wax on the tire side surface.

[0041] The heights H52, H53 of the ridges 52, 53 are defined as the distance from the top of the ridges 52, 53 to the bottom surface of the housing 51, as shown in Figure 7, and more specifically, are measured as the distance from the top of the ridges 52, 53 to the bottom of the valley between adjacent ridges 52, 52; 52, 53.

[0042] 7 , the widths W52A, W53A of the tops of the ridges 52, 53, relative to the widths W52B, W53B of the bases of the ridges 52, 53, are in the ranges of 0≦W52A / W52B≦0.90 and 0≦W53A / W53B≦0.90, and preferably in the ranges of 0.10≦W52A / W52B≦0.70 and 0.10≦W53A / W53B≦0.70. The above lower limits prevent deterioration in the processability of the ridges 52, 53, which would otherwise be caused by the tops of the ridges being too thin, and the above upper limits improve the blackening effect of the ridges 52, 53 on the tire side surfaces.

[0043] The widths W52A, W52B, W53A, and W53B of the ridges 52 and 53 are measured as widths in a cross section perpendicular to the longitudinal direction of the ridges 52 and 53. The widths W52B and W53B of the bases of the ridges 52 and 53 are defined as the widths of the bottom surfaces of the ridges 52 and 53 (in FIG. 7 , the contact surfaces between the bases of the ridges 52 and 53 and the bottom surface of the housing 51), and are specifically measured as the distance between imaginary lines connecting the valley bottoms of adjacent ridges 52 and 53.

[0044] 2, as described above, the ridge region 5 is made up of the housing 51 and the first and second ridges 52, 53 arranged within the housing 51 (see FIGS. 5 and 7). However, this is not limiting, and the housing 51 may be omitted, and the ridge region 5 may be made up of only the first and second ridges 52, 53 (not shown). For example, the first and second ridges 52, 53 may protrude from the same plane as the peripheral region 3. Even with such a configuration, the visibility of the marking portion 2 can be improved.

[0045] 2, the peripheral region 3 is a smooth surface. This configuration is preferable because it improves the visibility of the marking portion 2, which is composed of the housing 51 and the first and second ridges 52, 53. However, this is not limiting, and the peripheral region 3 may also be a textured surface with a surface treatment (not shown). The textured surface may be configured with an array of multiple textured portions, for example, an array of multiple longitudinal ridges or multiple grooves, or an array of multiple hemispherical or conical protrusions or multiple depressions.

[0046] [Planar Shape of Ridge] As shown in Fig. 5, the ridge region 5 includes a plurality of ridge units U (UA to UD). The figure shows four adjacent ridge units U. In the ridge region 5, a large number of ridge units U are repeatedly arranged in a predetermined arrangement pattern in the planar direction of the tire side portion.

[0047] The ridge unit U, i.e., the ridge per unit that serves as the motif of the ridge region 5, is made up of first and second ridges 52, 53. In addition, in a plan view of the tire side surface, the first ridge 52 has a ring-shaped structure, and the second ridge 53 has a linear structure. Therefore, the ridge unit U is made up of a combination of the ring-shaped first ridge 52 and the linear second ridge 53.

[0048] The annular structure of the first ridge 52 is a structure formed by connecting both ends of a linear or longitudinal shape in plan view, and is not limited to a complete annular shape, but includes a substantially annular shape with a minute gap of less than 0.50 mm, preferably less than 0.40 mm. This ensures the arrangement density of the first ridges 52 in the ridge region 5 and ensures the blackening effect of the ridge region 5.

[0049] The first ridge 52 is formed by connecting two or more annular protrusions 521a to 521c and at least one annular recess 522a to 522c.

[0050] The annular protrusions 521a-521c have a smoothly curved arch shape. Specifically, as shown in FIG. 6 , a portion of the first ridge 52 having the above-described annular structure or notched annular structure bulges in a direction away from the ridge center O, thereby forming the annular protrusions 521a-521c. This configuration promotes diffuse reflection of light between the ridges, improving the visual angle uniformity of the ridge region 5, i.e., the uniformity of the blackening effect of the ridge region 5 when viewed from different directions. This improves the visibility of the tire side surface.

[0051] 6, the annular protrusions 521a to 521c have a widened portion (reference numeral omitted in the figure) that widens from the ridge center O toward the maximum protrusion position. Therefore, the annular protrusions 521a to 521c have a constricted portion between the ridge center O and the maximum protrusion position, and also have an end portion that bulges out in an arc toward the protrusion side. The maximum width D21 of the annular protrusions 521a to 521c is in the range of 0.30 mm≦D21≦5.00 mm, and preferably in the range of 0.50 mm≦D21≦4.00 mm. In this configuration, compared to a configuration (not shown) in which a pair of ridge portions constituting each of the annular protrusions 521a to 521c extend at a constant distance from each other, the periphery length of the curved portion in the annular protrusions 521a to 521c is increased, improving the blackening effect of the ridge region 5 and the viewing angle uniformity of the ridge region 5.

[0052] The maximum width D21 of the annular convex portions 521a to 521c is measured as the maximum value of the width in the direction perpendicular to the protruding direction of the annular convex portions 521a to 521c.

[0053] Furthermore, two or more annular protrusions 521a to 521c protrude radially from the ridge center O, i.e., in mutually different directions. Furthermore, the two or more annular protrusions 521a to 521c are arranged at predetermined circumferential intervals θa to θc. In this case, the ratio of the maximum value to the minimum value of the circumferential intervals θa to θc of the annular protrusions 521a to 521c is in the range of 1.00 to 1.50, and preferably in the range of 1.00 to 1.30. This distributes the protruding directions of the annular protrusions 521a to 521c, improving the viewing angle uniformity of the ridge region 5.

[0054] The ridge center O is defined as the center of the smallest circle that contains the first ridge 52, i.e., the smallest containing circle M.

[0055] The circumferential intervals θa to θc between the annular convex portions 521a to 521c are defined as angles formed by an imaginary line passing through the ridge center O and the maximum protruding positions of the annular convex portions 521a to 521c.

[0056] The outer diameter Rm of the smallest including circle M is in the range of 0.80 mm≦Rm≦20.00 mm, and preferably in the range of 1.00 mm≦Rm≦10.00 mm.

[0057] The annular recesses 522a to 522c have a shape recessed toward the ridge center O and are disposed between adjacent annular protrusions 521a, 521b; 521b, 521c; 521c, 521a. Specifically, as shown in FIG. 6, the annular recesses 522a to 522c are formed so as to be concave with respect to the tangents to adjacent annular protrusions 521a, 521b; 521b, 521c; 521c, 521a. The annular recesses 522a to 522c also have smoothly curved arch shapes. With this configuration, the first ridge 52 has at least one annular recess 522a to 522c, which increases the periphery length of the first ridge 52 and improves the blackening effect of the ridge region 5.

[0058] The first ridge 52 preferably includes one or more, more preferably two or more, annular recesses 522a to 522c. The recess amount D22 of the annular recesses 522a to 522c, relative to the outer diameter Rm of the smallest including circle M, is in the range of 0.05≦D22 / Rm≦0.50, and preferably in the range of 0.10≦D22 / Rm≦0.40.

[0059] The recess amount D22 of the annular recesses 522a to 522c is defined as the distance between a tangent line contacting the adjacent annular protrusions 521a, 521b; 521b, 521c; 521c, 521a and the maximum recess position of the annular recesses 522a to 522c.

[0060] 6, for example, in a plan view of the tire side surface, the first ridge 52 has an annular structure formed by three annular convex portions 521a to 521c and three annular concave portions 522a to 522c alternately connected in the circumferential direction. Each of the three annular convex portions 521a to 521c is inscribed in the minimum including circle M and is arranged at circumferential intervals θa to θc of 120 degrees. Therefore, the three annular convex portions 521a to 521c are arranged point-symmetrically with respect to the ridge center O.

[0061] 5, multiple ridge units U are repeatedly arranged in the planar direction of the tire side portion and are arranged in close proximity to each other. In this case, the separation distance Dr between adjacent first ridges 52 is in the range of 0.10 mm≦Dr≦1.10 mm, and preferably in the range of 0.20 mm≦Dr≦0.80 mm. The lower limit ensures the light absorption effect due to the gap between adjacent first ridges 52, while the upper limit ensures the light absorption rate between adjacent first ridges 52, thereby ensuring the blackening effect of the ridge region 5. As will be described later, adjacent first ridges 52 may be connected to each other (see FIG. 17).

[0062] The separation distance Dr between adjacent first ridges 52, 52 is measured as the distance between the center lines of the first ridges 52, 52 in a plan view. However, in a configuration in which adjacent ridges have a connection portion, the separation distance Dr is measured excluding this connection portion.

[0063] 5 , the annular convex portion 521a of one first ridge 52 of a pair of adjacent first ridges 52, 52 is inserted into the annular concave portion 522b of the other first ridge 52. Specifically, the annular convex portion 521a of one first ridge 52 crosses a tangent line that contacts the adjacent annular convex portions 521b, 521c of the other first ridge 52 and is inserted into the annular concave portion 522b of the other first ridge 52. In this configuration, the adjacent first ridges 52, 52 are arranged so as to overlap each other, thereby increasing the arrangement density of the ridges 52 and improving the blackening effect of the ridge region 5.

[0064] Furthermore, the overlap amount Do between the annular convex portion 521a of one first ridge 52 and the annular concave portion 522b of the other first ridge 52 is in the range of 0.10≦Do / Rm, and preferably in the range of 0.20≦Do / Rm, relative to the outer diameter Rm of the smallest including circle M. At the upper limit of the ratio Do / Rm, the annular convex portion 521a of one first ridge 52 and the annular concave portion 522b of the other first ridge 52 are in contact with each other, and the overlap amount Do is equal to the concave amount D22 (see FIG. 6 ) of the annular concave portions 522a to 522c (Do=D22).

[0065] Furthermore, it is preferable that two or more annular convex portions 521a to 521c of one first ridge 52 are inserted into the annular recessed portions 522a to 522c of two or more other adjacent first ridges 52. That is, it is preferable that one first ridge 52 has a first annular convex portion 521a of two or more annular convex portions 521a to 521c inserted into the annular recessed portion 522b of one adjacent first ridge 52, and a second annular convex portion 521c inserted into the annular recessed portion (reference numeral omitted in the figure) of the other adjacent first ridge 52.

[0066] For example, in the configuration of FIG. 5 , each of the first ridges 52 of the multiple ridge units U (UA to UD) has three annular convex portions 521a to 521c and three annular concave portions 522a to 522c (see FIG. 6 ). Furthermore, by arranging a large number of ridge units U in a predetermined arrangement pattern, one first ridge 52 is surrounded by six adjacent first ridges 52 (not shown). At this time, the three annular convex portions 521a to 521c (see FIG. 6 ) of one first ridge 52 are inserted into the annular concave portions 522a to 522c of the three first ridges 52, and the annular convex portions 521a to 521c of the remaining three first ridges 52 are inserted into the three annular concave portions 522a to 522c of one first ridge 52. As a result, one first ridge 52 and the six surrounding first ridges 52 are arranged to overlap each other.

[0067] 6, the first ridge 52 has a shape formed by curving a single line, a so-called unicursal shape. Such a configuration is preferable in that it improves the workability of the first ridge 52. However, the first ridge 52 is not limited to this, and may have a branch portion that branches off in a T-shape or a Y-shape from a main portion that forms the above-mentioned annular structure or notched annular structure (not shown). Such a configuration is preferable in that it increases the linear density of the ridge 52 and enhances the blackening effect of the ridge region 5.

[0068] 6, the entire first ridge 52 has a curved shape with a continuous curvature. That is, the first ridge 52 has a shape formed by smoothly connecting multiple arcs, and therefore does not have any straight portions or L-shaped bent corners. This configuration is preferable in that it improves the viewing angle uniformity of the ridge region 5. However, this is not limiting, and a portion of the first ridge 52 may have a straight portion (not shown). In this case, the length of the straight portion is within a range of 70% or less, preferably 65% ​​or less, of the outer diameter Rm of the smallest encompassing circle M of the first ridge 52. Also, a portion of the first ridge 52 may have a corner (not shown).

[0069] 6, the first ridge 52 has a curved shape with a continuous curvature as described above, and therefore does not have a pair of straight line portions arranged in parallel. Furthermore, as shown in FIG. 5, adjacent first ridges 52, 52 do not have a pair of straight line portions arranged in parallel. This configuration is preferable in that the absence of parallel straight line portions improves the viewing angle uniformity of the ridge region 5. Even in a configuration in which adjacent curved lines are spaced a fixed distance apart (see FIG. 5), the blackening effect of the ridge region 5 when viewed from different directions is properly ensured.

[0070] As described above, the second ridge 53 has a linear structure, i.e., an open structure with two ends, and extends along the inner periphery of the first ridge 52 as shown in Fig. 6. Specifically, the second ridge 53 extends parallel to the first ridge 52 while being spaced a predetermined distance from the inner periphery wall surface of the first ridge 52, thereby forming a double ridge structure. This promotes the light absorption rate and diffuse reflection between the first ridge 52 and the second ridge 53, improving the blackening effect of the ridge region 5.

[0071] Furthermore, the distance Dr' (see FIG. 6) between the first ridge 52 and the second ridge 53 is in the range of 0.10 mm≦Dr'≦1.10 mm, and preferably in the range of 0.20 mm≦Dr'≦0.80 mm. The lower limit ensures the light absorption effect due to the gap between the first and second ridges 52, 53, while the upper limit ensures the light absorption rate between the first and second ridges 52, 53, thereby ensuring the blackening effect of the ridge region 5. As will be described later, the first and second ridges 52, 53 may be partially connected to each other (not shown).

[0072] The distance Dr' between adjacent ridges 52, 53 is measured as the distance between the center lines of the ridges 52, 53 in a plan view. However, in a configuration in which adjacent ridges have a connection, the distance Dr' is measured excluding this connection.

[0073] Furthermore, the periphery length L2 (dimension symbols omitted in the drawing) of the second ridge 53 is in the range of 0.10≦L2 / L1≦0.80, and preferably in the range of 0.20≦L2 / L1≦0.60, relative to the periphery length L1 of the first ridge 52. The above lower limit ensures the length over which the first ridge 52 and the second ridge 53 extend in parallel, ensuring the light absorption effect of the gap between the first ridge 52 and the second ridge 53, and the above upper limit prevents deterioration in the cleaning ability of the tire side portion due to the second ridge 53 being long.

[0074] The periphery lengths L1 and L2 of the ridges 52 and 53 are measured as the extension lengths of the center lines in a plan view of the ridges 52 and 53. In addition, in a configuration in which the second ridge 53 is composed of a plurality of short linear portions 531a to 531c and 532a to 532b as shown in Figure 6, the periphery length L2 of the second ridge 53 is calculated as the sum of the lengths of these short linear portions 531a to 531c and 532a to 532b.

[0075] As shown in FIG. 6, the second ridge 53 has two or more main linear portions 531a to 531c and at least one sub-linear portion 532a to 532c.

[0076] In a plan view of the tire side surface, the main linear portions 531a to 531c extend along the two or more annular convex portions 521a to 521c of the first ridge 52. Specifically, the main linear portions 531a to 531c have curved shapes that follow the wall shapes of the ends of the protruding sides of the annular convex portions 521a to 521c, and extend parallel to the inner circumferential surfaces of the annular convex portions 521a to 521c. This increases the arrangement density of the ridges at the ends of the annular convex portions 521a to 521c, improving the blackening effect of the ridge region 5.

[0077] In a plan view of the tire side surface, the secondary linear portions 532a to 532c extend in the longitudinal direction of each of the two or more annular convex portions 521a to 521c of the first ridge 52. Specifically, the secondary linear portions 532a to 532c are arranged in the region between the end of each of the annular convex portions 521a to 521c and the center of the minimum including circle M, and extend parallel to the trunk portions of the annular convex portions 521a to 521c. This increases the arrangement density of the ridges in the trunk portions of the annular convex portions 521a to 521c, improving the blackening effect of the ridge region 5.

[0078] 6, the first ridge 52 has an annular structure formed by alternatingly connecting three annular convex portions 521a to 521c and three annular concave portions 522a to 522c, as described above. Furthermore, the annular convex portions 521a to 521c have widened portions (reference numerals omitted in the figure) that widen from the ridge center O toward the maximum protrusion position. Therefore, the annular convex portions 521a to 521c have end portions that bulge in an arc toward the protrusion side, and also have a constricted portion between the ridge center O and the maximum protrusion position.

[0079] Furthermore, the second ridge 53 includes three main linear portions 531a to 531c and three sub-linear portions 532a to 532c, so that a set of main linear portions 531a to 531c and three sub-linear portions 532a to 532c is arranged on each of the annular convex portions 521a to 521c of the first ridge 52. Specifically, the main linear portions 531a to 531c of the second ridge 53 have an arc shape that follows the curvature of the ends of the annular convex portions 521a to 521c of the first ridge 52, and are arranged one at a time on the bulging ends of the three annular convex portions 521a to 521c. This increases the arrangement density of ridges on the bulging ends of the annular convex portions 521a to 521c.

[0080] Additionally, the secondary linear portions 532a to 532c of the second ridge 53 extend along the center lines of the trunks of the annular convex portions 521a to 521c of the first ridge 52. The ridges are arranged at a higher density in the intermediate regions of the trunks of the annular convex portions 521a to 521c. Additionally, each of the secondary linear portions 532a to 532c is spaced apart from each of the main linear portions 531a to 531c. This prevents deterioration in the cleaning performance of the tire sidewalls, which would otherwise be caused by the two portions being contiguous.

[0081] It is to be noted that, without being limited to the above, the main linear portions 531a to 531c of the second ridge 53 may be omitted, or the secondary linear portions 532a to 532c may be omitted (not shown). Furthermore, the second ridge 53 may be disposed on only a portion of the annular convex portions 521a to 521c of the first ridge 52 (not shown). Furthermore, the second ridge 53 may have linear portions different from the above-described main linear portions 531a to 531c and secondary linear portions 532a to 532c (not shown).

[0082] [Tire Manufacturing Method] The tire 1 is manufactured using a tire molding die capable of transferring the above-described ridge region 5 onto the tire side surface.

[0083] Specifically, the tire 1 is manufactured, for example, by the following manufacturing process. First, tire components such as bead wires that form the bead cores, carcass plies that form the carcass layer, belt plies that form the belt layer, tread rubber, sidewall rubber, and rim cushion rubber are placed in a molding machine to form a green tire (not shown). Next, the green tire is loaded into a tire vulcanization mold (not shown) that includes a tire molding die. Next, the green tire is expanded radially outward by a pressure device and abuts against the tire molding die. Next, the tire vulcanization mold is heated, causing rubber molecules and sulfur molecules in the green tire to bond and vulcanization to proceed. At this time, the shape of the molding surface of the tire molding mold is transferred to the outer peripheral surface of the green tire, thereby forming the tire side surface. Then, the tire after vulcanization is pulled out and removed from the tire vulcanization mold.

[0084] The ridge region 5 on the tire side surface is formed by irregularities formed on the molding surface of the tire mold. The irregularities on the molding surface of the tire mold are formed by, for example, laser processing.

[0085] 8 to 17 are explanatory diagrams showing modified examples of the ridge region 5 shown in Fig. 5. Fig. 18 is an explanatory diagram showing a modified example of the ridge region 5 shown in Fig. 2. In these diagrams, the same components as those described above are given the same reference numerals, and their description will be omitted.

[0086] 5, as described above, the first ridge 52 (see FIG. 6) has an annular structure formed by alternatingly connecting three annular convex portions 521a-521c and three annular concave portions 522a-522c. Furthermore, a plurality of ridge units U (UA-UD) are arranged vertically and horizontally at predetermined intervals with the annular convex portions 521a-521c oriented in the same direction.

[0087] 8, the first row in which the annular protrusions 521a to 521c are aligned in one direction and the second row in which the annular protrusions 521a to 521c are aligned in the other direction are alternately arranged. In this way, the annular protrusions 521a to 521c do not need to be aligned in the same direction.

[0088] 5, the first ridge 52 has a ring-shaped structure formed by alternately connecting three ring-shaped protrusions 521a to 521c and three ring-shaped recesses 522a to 522c, and has a structure that is point-symmetric with respect to the ridge center O, which is the center of the minimum inclusive circle M, as shown in FIG. 6. The ridge center O is located within the region surrounded by the ring-shaped structure of the first ridge 52.

[0089] 9, as shown in Fig. 10, one of the three annular recesses 522a to 522c (annular recess 522b) is recessed more than the other two (annular recesses 522a, 522c), and the recess amount D22 is set to approximately 0.40% of the outer diameter Rm of the minimum including circle M. In addition, the ridge center O is outside the region surrounded by the annular structure of the first ridge 52.

[0090] 5, the first ridge 52 has an annular structure formed by alternately connecting three annular convex portions 521a to 521c and three annular concave portions 522a to 522c, and the circumferential intervals θa to θc between the three annular convex portions 521a to 521c are set to approximately 120 degrees, as shown in Fig. 6. The three first ridges 52 adjacent to each other in a truss shape are arranged with the annular convex portions 521a to 521c inserted into the annular concave portions 522a to 522c.

[0091] 11, the first ridge 52 has an annular structure formed by alternately connecting four annular convex portions 521a to 521d and four annular concave portions 522a to 522d, and the circumferential intervals θa to θd between the four annular convex portions 521a to 521d are set to approximately 90 degrees, as shown in Fig. 12. The four first ridges 52 adjacent to each other in a lattice pattern are arranged with the annular convex portions 521a to 521d inserted into the annular concave portions 522a to 522d, as shown in Fig. 11.

[0092] Similarly, in the configuration of Fig. 13, the first ridge 52 has an annular structure formed by alternately connecting six annular convex portions 521a to 521f and six annular concave portions 522a to 522f, and the circumferential intervals θa to θd between the six annular convex portions 521a to 521d are set to approximately 60 degrees, as shown in Fig. 14. Then, as shown in Fig. 13, four first ridges 52 adjacent to each other in a lattice pattern are arranged with the annular convex portions 521a to 521f inserted into the annular concave portions 522a to 522f.

[0093] 15, on the other hand, the first ridge 52 has an annular structure formed by alternately connecting two annular convex portions 521a, 521b and two annular concave portions 522a, 522b, and the circumferential distance θa between the two annular convex portions 521a, 521b is set to approximately 180 degrees, as shown in Fig. 16. In addition, in a pair of adjacent ridge units UA, UB, the annular convex portion 521a of one first ridge 52 is inserted into the annular concave portion 522a of the other first ridge 52, as shown in Fig. 15.

[0094] In the configuration of FIG. 5, the first ridge 52 has a continuous annular structure (see FIG. 6), and a plurality of ridge units UA to UD are arranged at intervals from one another in a predetermined arrangement pattern.

[0095] In contrast, in the configuration of Fig. 17, the arranged multiple ridge units UA-UD are connected to one another and are also partially separated so that the ridge region 5 can be formed in a single stroke. Specifically, the molding surface of the tire molding die has irregularities for forming the ridge region 5, and the arrangement structure of the multiple ridge units UA-UD in the ridge region 5 is designed so that the irregularities of this tire molding die can be formed in a single stroke by laser processing. For example, in the configuration of Fig. 17, adjacent ridge units UA, UB; UC, UD are connected to one another and each of the ridge units UA-UD is divided into two so that the ridge portion represented by the solid line is the outgoing path and the ridge portion represented by the dashed line is the returning path. In this case, if the ridge division width is less than 0.50 [mm], it can be said that the ridge units UA-UD are substantially continuous. Furthermore, without being limited to the above, each ridge unit UA to UD may have a ring-shaped structure that is not divided into two by having the outward and return paths of the ridge portion come into contact with or overlap each other (not shown). Note that the ridge portion shown by the dashed dotted line in Figure 17 is formed in a process separate from the outward and return paths described above.

[0096] 2, as described above, the marking portion 2 is made up of the ridge region 5, and the peripheral region 3 surrounding the marking portion 2 is made up of a smooth surface. This configuration is preferable in that the marking portion 2 is colored black, improving the visibility of the marking portion 2.

[0097] 18, the mark portion 2 is made up of a smooth surface, and the peripheral region 3 surrounding the mark portion 2 is made up of a ridge region 5. Specifically, the ridge region 5 is made up of a housing 51 (not shown; see FIG. 7) that surrounds the outline of the mark portion 2 within an area defined by a pair of thin ribs 41, 42, and a plurality of ridge units UA to UD arranged in this housing 51. In this configuration, the peripheral region 3 is colored black, and the mark portion 2 appears with an appearance in which the contrast is reversed.

[0098] As described above, [1] the tire 1 includes a ridge region 5 on the tire side surface (see FIG. 2) that is formed by an arrangement of a plurality of ridge units U (UA to UD: see FIG. 5). Each of the plurality of ridge units U includes, in a plan view of the tire side surface, a first ridge 52 that has an annular structure and a second ridge 53 that has a linear structure and extends along the inner periphery of the first ridge 52 (see FIG. 6).

[0099] In this configuration, (1) the tire side surface includes a ridge region 5 formed by an array of multiple ridge units U. Therefore, in a plan view of the tire side portion, the light absorption rate in the ridge region 5 (marking region 2 in FIG. 3 ) is relatively higher than the light absorption rate in other regions (peripheral region 3 in FIG. 3 ). This makes the ridge region 5 relatively darker, creating a clear contrast on the tire side surface. Furthermore, (2) the second ridge 53 extends along the inner periphery of the curved first ridge 52, promoting light absorption and diffuse reflection between the first ridge 52 and the second ridge 53. These advantages result in improved visibility of the tire side surface. Furthermore, (3) the second ridge 53 has a linear structure, resulting in improved cleaning performance of the tire side portion compared to a double structure in which the first and second ridges have an annular structure.

[0100] [2] In the tire 1 described in [1] above, the first ridge 52 is configured by connecting two or more annular convex portions 521a-521c that protrude radially from the ridge center and at least one annular concave portion 522a-522c that is concave toward the ridge center O. With this configuration, the first ridge 52 has two or more annular convex portions 521a-521c, which promotes diffuse reflection of light between the ridges, advantageously improving the visual angle uniformity of the ridge region 5, i.e., the uniformity of the blackening effect of the ridge region 5 when the tire side surface is viewed from different directions. Furthermore, the first ridge 52 has at least one annular concave portion 522a-522c, which advantageously increases the periphery length of the first ridge 52 and improves the blackening effect of the ridge region 5.

[0101] [3] In addition, in the tire 1 described in [2] above, the two or more annular protrusions 521 a to 521 c have a smoothly curved arch shape (see FIG. 6 ). This configuration has the advantage of promoting diffuse reflection of light between the ridges and improving the visual angle uniformity of the ridge region 5.

[0102] [4] In addition, in the tire 1 described in [2] or [3] above, two or more annular protrusions 521a to 521c have widened portions that widen from the ridge center O toward the maximum protrusion position (see FIG. 6 ). Compared to a configuration (not shown) in which a pair of ridge portions constituting each of the annular protrusions 521a to 521c extend at a constant distance from each other, this configuration has the advantage that the periphery length of the curved portions in the annular protrusions 521a to 521c is increased, improving the blackening effect of the ridge region 5 and also improving the visual angle uniformity of the ridge region 5.

[0103] [5] In the tire 1 according to any one of the above items [2] to [4], at least one of the annular recesses 522 a to 522 c has a smoothly curved arch shape (see FIG. 6 ). This configuration has the advantage of promoting diffuse reflection of light between the ridges and improving the visual angle uniformity of the ridge region 5.

[0104] [6] In the tire 1 according to any one of the above [2] to [5], the distance Dr between adjacent first ridges 52 is in the range of 0.10 mm≦Dr≦1.10 mm (see FIG. 5 ). This ensures the density of the ridges, and has the advantage of improving the blackening effect of the ridge region 5.

[0105] [7] The tire 1 is the tire 1 described in any one of the above [2] to [6], wherein one of the three or more annular convex portions 521a to 521c of one of the adjacent first ridges 52, 52 (in FIG. 5, the annular convex portion 521a) is inserted into at least one annular concave portion 522b of the other first ridge 52. With this configuration, the adjacent first ridges 52, 52 are arranged to overlap each other, which has the advantage of increasing the ridge arrangement density and improving the blackening effect of the ridge region 5.

[0106] [8] In addition, in the tire 1 described in any one of [2] to [7] above, the recess amount D22 of the annular recesses 522a to 522c is in the range of 0.05≦D22 / Rm≦0.50, relative to the outer diameter Rm of the smallest encompassing circle M of the first ridge 52. The lower limit ensures the periphery length of the first ridge 52, ensuring the blackening effect of the ridge region 5, while the upper limit has the advantage of avoiding imbalance in the shape of the first ridge 52 caused by the annular recesses 522a to 522c being excessively large.

[0107] [9] In the tire 1 according to any one of the above items [2] to [8], the second ridge 53 has, in a plan view of the tire side surface, two or more main linear portions 531a to 531c extending along the two or more annular convex portions 521a to 521c of the first ridge 52 (see FIG. 6 ). This increases the arrangement density of the ridges at the ends of the annular convex portions 521a to 521c, which has the advantage of improving the blackening effect of the ridge region 5.

[0108]

[10] In the tire 1 according to any one of the above [2] to [9], the second ridge 53 has, in a plan view of the tire side surface, at least one sub-linear portion 532a to 532c extending in the longitudinal direction of each of the two or more annular convex portions 521a to 521c of the first ridge 52. This increases the ridge arrangement density in the trunk portions of the annular convex portions 521a to 521c, which has the advantage of improving the blackening effect of the ridge region 5.

[0109]

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

[10] , the plurality of ridge units UA to UD are connected to one another (see FIG. 17 ), which has the advantage of facilitating the processing of a vulcanization mold for forming the ridge region 5.

[0110]

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

[11] , the outer diameter Rm of the smallest encompassing circle M of the first ridges 52 is in the range of 0.80 mm≦Rm≦20.00 mm. The lower limit ensures the workability of the first ridges 52, while the upper limit has the advantage of ensuring the arrangement density of the first ridges 52 in the ridge region 5.

[0111]

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

[12] , the distance Dr' (see FIG. 6) between the first ridge 52 and the second ridge 53 is in the range of 0.10 mm≦Dr'≦1.10 mm. The lower limit ensures the light absorption effect due to the gap between the first and second ridges 52, 53, while the upper limit ensures the light absorption rate between the first and second ridges 52, 53, thereby ensuring the blackening effect of the ridge region 5.

[0112]

[14] In addition, in the tire 1 described in any one of the above [1] to

[13] , the periphery length L2 (dimension symbols omitted in the drawing) of the second ridge 53 is in the range of 0.10≦L2 / L1≦0.80 relative to the periphery length L1 of the first ridge 52. The above lower limit ensures the length over which the first ridge 52 and the second ridge 53 extend in parallel, ensuring the light absorption effect of the gap between the first ridge 52 and the second ridge 53, while the above upper limit has the advantage of suppressing deterioration in the cleaning ability of the tire side portion caused by the second ridge 53 being long.

[0113] [Applicable Objects] In this embodiment, as described above, a pneumatic tire has been described as an example of a tire. However, the present invention is not limited to this, and the configuration described in this embodiment can be applied to other tires as desired within the scope of what is obvious to those skilled in the art. Examples of other tires include airless tires and solid tires.

[0114] FIG. 19 is a table showing the results of performance tests of the tire according to the embodiment of the present invention.

[0115] In this performance test, several types of test tires were evaluated for (1) the blackening performance of the ridge region and (2) the visual angle uniformity performance of the ridge region. Also, a test tire having a tire size of 255 / 35R19 (96Y) was mounted on a rim having a rim size of 19x9J, and an internal pressure specified by JATMA was applied to this test tire.

[0116] (1) In the evaluation of the visibility of the marking, an inspector visually inspects the tire side of the test tire from a distance of 5 m and performs a sensory evaluation of the visibility of the ridge region, particularly the degree of blackening of the ridge region (contrast with the surrounding area). This evaluation is performed using an index evaluation with the comparative example as the standard (100), and the higher the value, the better.

[0117] (2) In the evaluation of the visual angle uniformity performance of the ridge region, an inspector visually inspects the tire side of the test tire from a distance of 5 m while rotating it by 120 degrees at a time, and performs a sensory evaluation of the visibility of the ridge region, particularly whether the degree of blackening of the ridge region is uniform. This evaluation is performed using an index evaluation with the comparative example as the standard (100), and the higher the value, the better.

[0118] 1 to 7, the marking portion 2 is composed of a ridge region 5 formed by an arrangement of multiple ridge units UA to UD. The first ridge 52 has an annular structure formed by alternatingly connecting three annular convex portions 521a to 521c and three annular concave portions 522a to 522c, and the second ridge 53 has three main linear portions 531a to 531c and three sub-linear portions 532a to 532c. The ratio L2 / L1 of the periphery length L2 of the second ridge 53 to the periphery length L1 of the first ridge 52 is 0.20. The outer diameter Rm of the minimum encompassing circle M is 7.0 mm.

[0119] The test tire of the comparative example has six straight branch portions branching out in an asterisk shape from the center of the ridge.

[0120] As the test results show, the test tires of the examples have improved blackening performance in the ridge area and visual angle uniformity performance.

[0121] 1 tire; 11 bead core; 12 bead filler; 13 carcass layer; 14 belt layer; 141, 142 cross belt; 143 belt cover; 15 tread rubber; 16 sidewall rubber; 17 rim cushion rubber; 20 rim; 2 marking portion; 2A to 2E elements; 3 peripheral region; 41, 42 narrow rib; 5 ridge region; 51 housing; 52 first ridge; 521a to 521f annular convex portion; 522a to 522f annular concave portion; 523 second ridge; 531a to 531f main linear portion; 532a to 532f secondary linear portion; U, UA to UD ridge unit

Claims

1. A tire having a ridge region formed by arranging a plurality of ridge units on a tire side surface, wherein each of the plurality of ridge units includes a first ridge having an annular structure and a second ridge having a linear structure and extending along the inner circumference of the first ridge in a plan view of the tire side surface.

2. The tire according to claim 1, wherein the first ridge is formed by connecting two or more annular convex portions protruding radially from a ridge center and at least one annular concave portion recessed toward the ridge center.

3. The tire according to claim 2, wherein the two or more annular convex portions have a smoothly curved arch shape.

4. The tire according to claim 2 or 3, wherein the two or more annular convex portions have a widened portion that widens from the ridge center toward a maximum protruding position.

5. The tire according to any one of claims 2 to 4, wherein the at least one annular concave portion has a smoothly curved arch shape.

6. The tire according to any one of claims 2 to 5, wherein a separation distance Dr between adjacent first ridges is in the range of 0.10 [mm] ≦ Dr ≦ 1.10 [mm].

7. The tire according to any one of claims 2 to 5, wherein one of the three or more annular convex portions of one of the adjacent first ridges is inserted into the at least one annular concave portion of the other first ridge.

8. The tire according to any one of claims 2 to 7, wherein a recess amount D22 of the annular concave portion is in the range of 0.05 ≦ D22 / Rm ≦ 0.50 with respect to an outer diameter Rm of a minimum enclosing circle M of the first ridge.

9. The tire according to any one of claims 2 to 8, wherein the second ridge has two or more main linear portions extending along each of the two or more annular convex portions of the first ridge in a plan view of the tire side surface.

10. The tire according to any one of claims 2 to 9, wherein the second ridge has at least one sub-linear portion extending in a longitudinal direction of each of the two or more annular convex portions of the first ridge in a plan view of the tire side surface.

11. The tire according to any one of claims 1 to 10, wherein the plurality of ridge units are connected to each other.

12. The tire according to claim 1, wherein an outer diameter Rm of a minimum enclosing circle M of the first ridge is in the range of 0.80 [mm] ≦ Rm ≦ 20.00 [mm].

13. The tire according to any one of claims 1 to 11, wherein the separation distance Dr' between the first ridge and the second ridge is in the range of 0.10 [mm] ≦ Dr' ≦ 1.10 [mm].

14. The tire according to any one of claims 1 to 12, wherein the peripheral length L2 of the second ridge is in the range of 0.10 ≦ L2 / L1 ≦ 0.80 with respect to the peripheral length L1 of the first ridge.

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