Tire

Abstract

To provide a tire which comprises a display object depicting a character, a graphic form, or a symbol on an exterior surface of a side wall part, and which is manufactured through a process of a polishing the surface of the display object, and in which a surface state of the display object is excellent.SOLUTION: A tire comprises a display object 10 on an exterior surface of a side wall part 2. In the tire, at least a part of a top face of a recess 11 constituting a contour line of a character, a graphic form, or a symbol exposes different color rubber embedded in a portion of the side wall part 2, and therefore, the display object 10 has a color different from that of the exterior surface of the side wall part 2. When a radial direction element 11r denotes a portion extending along the tire radial direction of the recess 11 constituting the display object 10, and a circumferential direction element 11c denotes a portion extending along the tire circumferential direction of the recess 11 constituting the display object 10, a width Wr of a top face of the radial direction element 11r and a width Wc of a top face of the circumferential direction element 11c satisfy a relationship of Wr / Wc≥1.2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tire having indicia depicting letters, figures or symbols on the outer surface of the sidewall portion. [Background technology]

[0002] Indications for displaying the manufacturer's name, brand name, etc., may be formed on the outer surface of the sidewall of a tire. In particular, in order to improve the visibility and decorativeness of the indications, the indications are formed from a different-colored rubber (e.g., white rubber) that is a different color from the color of the sidewall (usually black) (so-called "white letters"). When manufacturing such tires, at least a part of the portion corresponding to the sidewall of a green tire (the portion corresponding to the indications) is structured by laminating a different-colored rubber layer (white rubber layer) and a cover rubber layer (black rubber layer) that covers the different-colored rubber layer, the green tire is vulcanized, the indications are formed as convex portions protruding from the surface of the sidewall, and then the surface of the convex portions (cover rubber layer) is polished and removed to expose the white rubber layer, forming the indications made of different-colored rubber (see, for example, Patent Document 1).

[0003] In such tires, the process of polishing the surface of the markings (protruding parts) is performed by a dedicated polishing machine (buffing machine) or the like. This device rotates a polishing body (such as a grindstone) against the side of the tire that is mounted on a stand and rotates, and polishes the sidewall part (markings) of the tire in the thickness direction (the direction of the protruding height of the protruding parts) by an interval that is preset for each type of tire, so as to expose the embedded different color rubber on the tire surface (see, for example, Patent Document 2). When performing the polishing process (buffing process) with such a device, if the dimensions of the markings formed as the protruding parts are small, the rigidity of the markings (protruding parts) cannot be ensured, and problems such as the markings collapsing during polishing occur, which may cause the surface condition of the markings to deteriorate after polishing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-114732 A [Patent Document 2] Japanese Patent Application Publication No. 05-277925 Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a tire which has markings depicting letters, figures or symbols on the outer surface of the sidewall portion and is manufactured through a process of polishing the surface of the markings, and which makes it possible to improve the surface condition of the markings. [Means for solving the problem]

[0006] In order to achieve the above object, a tire of the present invention includes a tread portion extending circumferentially of the tire to form an annular shape, and a pair of sidewall portions arranged on either side of the tread portion, and an indicia depicting the outline of a letter, figure, or symbol is formed on the outer surface of the sidewall portion by the shape of the top surface of a protrusion protruding from the outer surface of the sidewall portion, and at least a portion of the top surface of the protrusion has a different color from the outer surface of the sidewall portion by exposing a different color rubber embedded in a portion of the sidewall portion, wherein, in the tire, when a portion of the protrusion constituting the indicia extending along the tire radial direction is defined as a radial element, and a portion of the protrusion constituting the indicia extending along the tire circumferential direction is defined as a circumferential element, a width Wr of the top surface of the radial element and a width Wc of the top surface of the circumferential element satisfy the relationship Wr / Wc ≧ 1.2. Effect of the Invention

[0007] The present inventors have conducted extensive research into the appearance defects of markings in tires manufactured through a process of polishing the surface of the convex parts that constitute the markings, and as a result have found that if the dimensions of the markings formed as the convex parts are small, when the polishing body rotates and comes into contact with the markings (convex parts), defects such as the markings (convex parts) collapsing in the rotation direction (polishing direction) of the polishing body occur, which causes the surface condition of the markings to deteriorate after polishing (the surface of the markings does not become smooth, and for example, scale-like irregularities occur).The present invention is based on this finding, and prevents the markings (convex parts) from collapsing by increasing the strength of the parts of the convex parts that are susceptible to load in the polishing direction (the parts extending in the direction perpendicular to the polishing direction, i.e., along the tire radial direction) that constitute the markings, thereby improving the surface condition of the markings after polishing. Specifically, in a display object of the type in which the protrusion depicts the outline of a character, figure, or symbol, the width of the top face of the protrusion (the width of the outline) was conventionally constant, whereas in the tire of the present invention, the width Wr of the top face of the radial element is configured to be larger than the width Wc of the top face of the circumferential element, and the ratio of these satisfies the relationship Wr / Wc≧1.2, so that the rigidity of the radial element that is susceptible to load in the polishing direction is ensured and the display object (protrusion) can be prevented from collapsing. As a result, the appearance defect of the display object caused by the collapse of the display object (protrusion) can be suppressed, and the surface of the display object after polishing can be made smooth.

[0008] In the tire of the present invention, the width Wr of the top surface of the radial element is preferably 2.5 mm or more. Also, the width Wc of the top surface of the circumferential element is preferably 2.0 mm or less. This ensures sufficient rigidity of the radial element that is susceptible to load in the grinding direction, which is advantageous in preventing the display object (protrusion) from collapsing.

[0009] In the tire of the present invention, the angle that the radial element forms with respect to the tire radial direction is preferably within a range of ±30°. By using a portion extending in the tire radial direction within such an angle range as the radial element, it is possible to effectively reinforce a portion that is likely to collapse when the surface of the indicia is polished, which is advantageous for improving the surface condition of the indicia.

[0010] In the tire of the present invention, it is preferable that the angle θr that the side surface of the protrusion makes with the normal direction of the outer surface of the sidewall portion in a cross section perpendicular to the radial element is larger than the angle θc that the side surface of the protrusion makes with the normal direction of the outer surface of the sidewall portion in a cross section perpendicular to the circumferential element. This ensures the thickness and volume of the radial element that is susceptible to load in the grinding direction, and further increases the rigidity, which is advantageous in preventing the display object (protrusion) from collapsing.

[0011] In the tire of the present invention, it is preferable that in a cross section perpendicular to the radial element, the side of the convex portion and the outer surface of the sidewall portion are smoothly connected via an arc-shaped connecting portion, and in a cross section perpendicular to the circumferential element, the side of the convex portion and the outer surface of the sidewall portion are smoothly connected via an arc-shaped connecting portion, and the radius of curvature Rr of the connecting portion in the radial element is larger than the radius of curvature Rc of the connecting portion in the circumferential element. This ensures the thickness and volume of the radial element that is susceptible to load in the grinding direction, and further increases the rigidity, which is advantageous in preventing the display object (convex portion) from collapsing.

[0012] In the present invention, the minimum width of the portion surrounded by the outline of the convex portion is preferably 2.0 mm or more. In an indication in which the convex portions depict the outline of a character, figure, or symbol, if the spacing between the convex portions is narrow, the bones of the mold for molding the portion surrounded by the convex portions (outline) become fine, making it difficult to properly mold the intended character, figure, or symbol.

[0013] In the present invention, it is preferable that the length L of the indicia in the tire radial direction is 25 mm or less. When the size of the indicia in the tire radial direction is small like this, the dimensions such as the width W of the top surface of the indicia are also small, and the indicia is likely to collapse when the surface is polished, so that the effect of the present invention can be more efficiently achieved by applying the present invention described above. [Brief description of the drawings]

[0014] [Figure 1]1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment of the present invention. [Diagram 2] FIG. 1 is an explanatory diagram showing an example of an indicia of a tire according to an embodiment of the present invention. [Diagram 3] 1A to 1C are explanatory diagrams illustrating the states of an object before and after polishing. [Figure 4] 1 is a cross-sectional view showing a display object according to an embodiment of the present invention. [Diagram 5] FIG. 11 is a cross-sectional view showing a display according to another embodiment of the present invention. [Figure 6] FIG. 2 is an explanatory diagram showing radial portions of an indicia of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

[0016] When the tire of the present invention is a pneumatic tire as shown in FIG. 1, it includes a tread portion 1 that contacts the road surface, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3 arranged on the tire radial inner side of the sidewall portions 2. In FIG. 1, the symbol CL indicates the tire equator, and the symbol E indicates the ground contact edge. Although not depicted in FIG. 1 because it is a meridian cross section, the tread portion 1, the sidewall portions 2, and the bead portions 3 each extend in the tire circumferential direction to form an annular shape, thereby forming a toroidal basic structure of a pneumatic tire. The following explanation using FIG. 1 is basically based on the meridian cross section shown in the figure, but each tire component extends in the tire circumferential direction to form an annular shape.

[0017] A carcass layer 4 is installed between a pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inner side to the outer side in the tire width direction around the bead cores 5 arranged in each bead portion 3. A bead filler 6 is arranged on the outer periphery of the bead cores 5, and the bead filler 6 is wrapped by the main body and folded back parts of the carcass layer 4. Meanwhile, a plurality of belt layers 7 (two layers in FIG. 1) are embedded on the outer periphery side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set to, for example, a range of 10° to 40°. Furthermore, at least one belt reinforcing layer 8 (two layers in FIG. 1) is provided on the outer periphery side of the belt layer 7. The belt reinforcing layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcing layer 8, the organic fiber cords are set at an angle of, for example, 0° to 5° with respect to the tire circumferential direction.

[0018] As described below, the present invention relates to indicia formed on the surface of the sidewall portion 2 of a tire, and therefore the basic structure (cross-sectional structure) of the tire is not limited to the general structure described above. In addition, the following description will be based on a pneumatic tire (a tire filled with air, an inert gas such as nitrogen, or other gases) as shown in Fig. 1 etc., but the present invention can be applied to various tires, including non-pneumatic tires, as long as the tire is provided with indicia depicting letters, figures, or symbols on the outer surface of the sidewall portion and is manufactured through a process of polishing the surface of the indicia.

[0019] In the present invention, as shown in Figures 1 and 2, a display 10 is provided on the outer surface of at least one of the pair of sidewall portions 2. The display 10 depicts a letter, figure, or symbol by the shape of the top surface of a protrusion 11 protruding from the outer surface of the sidewall portion 2. The display 10 of the present invention has a color different from that of the outer surface of the sidewall portion by exposing a different color rubber 12 embedded in a part of the sidewall portion 2 at least in part of the top surface of the protrusion 11 constituting the display 10. Since the outer surface of the sidewall portion of a tire is generally black, it is preferable that the different color rubber be white rubber from the viewpoints of visibility and decorativeness.

[0020] In more detail, the protrusion 11 constituting the display 10 is formed as a protrusion 11 in which a different color rubber 12 embedded in the sidewall portion 2 and a cover rubber 13 covering the different color rubber 12 are laminated as shown in Fig. 3(a), and then the surface of this protrusion 11 (a part of the cover rubber 13 and the different color rubber 12) is polished and removed to expose the different color rubber 12 as shown in Fig. 3(b), forming the display 10 in which at least a part of the top surface of the display 10 is made of the different color rubber 12. Note that Fig. 3(b) shows the state in which the upper part above the dashed line in Fig. 3(a) has been polished and removed. Since it is manufactured as described above, strictly speaking, the top surface of the protrusion 11 of the present invention is made of the different color rubber 12 in the region excluding the peripheral portion derived from the cover rubber 13.

[0021] The example shown in FIG. 2 depicts the letter "N." More specifically, the contour of the letter "N" is formed by the convex portion 11 whose top surface is made of a different color rubber 12, and the letter "N" is depicted as a whole by this contour (the convex portion 11) and the portion surrounded by the contour (the surface of the sidewall portion 2). The dashed line in FIG. 2 depicts the lower end of the convex portion 11 (the portion connected to the outer surface of the sidewall portion 2), and the area between the dashed line and the solid line in FIG. 2 corresponds to the side of the convex portion 11. In the following description, of the convex portion 11 constituting such an indication 10, the portion extending along the tire radial direction (the up-down direction in the figure) is referred to as the radial element 11r, and the portion extending along the tire circumferential direction (the left-right direction in the figure) is referred to as the circumferential element 11c.

[0022] In the present invention, as shown in the figure, the width Wr of the top surface of the radial element 11r is configured to be larger than the width Wc of the top surface of the circumferential element 11c, and the ratio Wr / Wc of these widths Wr and Wc satisfies the relationship Wr / Wc≧1.2, preferably 1.25≦Wr / Wc≦1.75. Note that these widths Wr and Wc are the widths of the top surface of each element measured along a direction perpendicular to the extension direction of the radial element 11r or the circumferential element 11c.

[0023] By setting the width of the top surface in this manner, the thickness of the radial element 11r is ensured, and the rigidity of the radial element 11r, which is susceptible to load in the polishing direction in the process of polishing the surface of the convex portion 11 constituting the display object 10, can be ensured, thereby preventing the display object 10 (convex portion 11) from collapsing, suppressing the resulting appearance defects of the display object 10, and making the surface of the display object 10 after buffing smooth. In particular, if the ratio Wr / Wc is less than 1.2, the thickness of the radial element 11r, which is susceptible to the above-mentioned load, cannot be sufficiently ensured, and the display object 10 (convex portion 11) cannot be prevented from collapsing.

[0024] In the display object 10 to which the present invention is applied, the width Wc of the top surface of the circumferential element 11c is preferably 2.0 mm or less, more preferably 1.5 mm to 2.0 mm. That is, in the conventional display object 10 (where the width of the top surface of the radial element 11r and the circumferential element 11c is common), when the width of the top surface is 2.0 mm or less (i.e., when the display object 10 is small), the above-mentioned collapse is likely to occur, so it is effective to apply the present invention to a tire in which the relatively narrower width Wc is 2.0 mm or less (a dimension in which collapse was likely to occur in the past). When the width Wc of the top surface of the circumferential element exceeds 2.0 mm, the collapse of the display object 10 (protrusion 11) is unlikely to occur even without applying the present invention, so the effect of applying the present invention is limited.

[0025] The width Wr of the top surface of the radial element 11r is preferably 2.5 mm or more, and more preferably 2.5 mm to 3.5 mm. By making the width Wr of the top surface of the radial element 11r sufficiently large in this way, it is advantageous to ensure the rigidity of the radial element 11r and prevent the display object 10 (protrusion 11) from falling down. In particular, when the width Wc of the top surface of the circumferential element 11c is 2.0 mm or less as described above, the balance between these widths Wr and Wc is good, and the display object (protrusion) can be effectively prevented from falling down.

[0026] The width Wc of the top surface of the circumferential element 11c preferably satisfies the relationship Wc / H≦1.0, more preferably 0.5≦Wc / H≦0.8, relative to the protruding height H of the protruding portion 11. When the protruding height H is large relative to the top surface width Wc, the display object 10 (protruding portion 11) is likely to collapse, and the effect of the present invention can be effectively achieved by applying the above-mentioned configuration of the present invention. When the ratio Wc / H of the width Wc and the protruding height H is in the relationship Wc / H>1.0, the protruding height H is small relative to the width Wc of the top surface of the protruding portion 11, and the rigidity of the protruding portion 11 is easily ensured, and the effect of applying the above-mentioned configuration of the present invention is limited.

[0027] In the present invention, from the viewpoint of increasing the rigidity of the radial element 11r, the angle (wall angle θr) formed by the side of the protrusion 11 with the normal direction of the outer surface of the sidewall portion 2 in a cross section perpendicular to the radial element 11r can be set to be larger than the angle (wall angle θc) formed by the side of the protrusion 11 with the normal direction of the outer surface of the sidewall portion 2 in a cross section perpendicular to the circumferential element 11c. This specification can ensure the thickness of the protrusion 11 on the lower side (part close to the surface of the sidewall portion 2) of the radial element 11r, and can further increase the rigidity of the radial element 11r, which is advantageous for preventing the display object 10 (protrusion 11) from falling down. In this specification, it is preferable to set the wall angle θr to, for example, 15° or more and 30° or less, the wall angle θc to, for example, 5° or more and 15° or less, and the difference between these wall angles to, for example, 5° or more and 20° or less.

[0028] Alternatively, from the viewpoint of increasing the rigidity of the radial element 11r, the side surface of the protrusion 11 and the outer surface of the sidewall portion 2 are smoothly connected via the arc-shaped connecting portion 14 in a cross section perpendicular to the radial element 11r, and the side surface of the protrusion 11 and the outer surface of the sidewall portion 2 are smoothly connected via the arc-shaped connecting portion 14 in a cross section perpendicular to the circumferential element 11c, and the radius of curvature Rr of the connecting portion 14 in the radial element 11r is larger than the radius of curvature Rc of the connecting portion 14 in the circumferential element 11c. Even in this specification, the thickness of the protrusion 11 on the lower side (the portion close to the surface of the sidewall portion 2) of the radial element 11r can be secured, and the rigidity of the radial element 11r can be further increased, which is advantageous in preventing the display object 10 (protrusion 11) from falling over. In this specification, it is preferable to set the radius of curvature Rr to, for example, 2.5 mm or more and 4.0 mm or less, the radius of curvature Rc to, for example, 1.5 mm or more and 2.0 mm or less, and the difference between these radii of curvature to, for example, 1.0 mm or more and 2.0 mm or less.

[0029] 4(a) and (b) are for explaining the wall angles θr and θc, and therefore the distinction between the different color rubber 12 and the cover rubber 13 is omitted. Similarly, FIG. 5(a) and (b) are for explaining the curvature radii Rr and Rc, and therefore the distinction between the different color rubber 12 and the cover rubber 13 is omitted.

[0030] As described above, the radial element 11r refers to a portion of the protrusion 11 constituting the display object 10 that extends along the tire radial direction (the vertical direction in the figure), and it is particularly preferable that the angle α that the radial element 11r forms with respect to the tire radial direction is within the range of ±30°. For example, in the example of FIG. 6 (depicting the alphabet "N" as in FIG. 2), the shaded portion corresponds to the radial element 11r, and the angle α that it forms with respect to the tire radial direction is all within the range of ±30°. By regarding the portion extending in the tire radial direction within such an angle range as the radial element 11r, it is possible to effectively reinforce the portion that is likely to collapse when the surface of the display object 10 is polished, which is advantageous for improving the surface condition of the display object 10. The angle α is measured based on the widthwise center of the top surface of the protrusion 11.

[0031] The tire indicia 10 to which the present invention is applied preferably has a length L along the tire radial direction of 25 mm or less. If the size of the indicia 10 in the tire radial direction is small, the dimensions of the widths Wr, Wc, etc. of the top surface of the indicia 10 are also small, and the indicia 10 is more likely to collapse when its surface is polished, so that the effect of the present invention can be more efficiently achieved by applying the present invention described above. The length L of the indicia 10 along the tire radial direction is the size of each character, figure, or symbol contained in the indicia 10, and is measured as the length along the tire radial direction between the upper end and lower end of the indicia 10 in the tire radial direction, as shown in Figures 1 and 2.

[0032] The cross-sectional height SH of the tire to which the present invention is applied is preferably 150 mm or less, and more preferably 120 mm to 140 mm. In a tire having such a small cross-sectional height, the size of the indicia 10 provided on the sidewall portion 2 in the tire radial direction tends to be small, and the dimensions such as the width W of the top surface of the indicia 10 also become small, and the indicia 10 is likely to collapse when the surface is polished. Therefore, by applying the present invention described above, the effects of the present invention can be exhibited more efficiently.

[0033] As described above, the present invention is an invention intended to reinforce the portions (radial elements 11r) where collapse is likely to occur by increasing the width of the top surface, and therefore it is not necessary to apply the above-mentioned setting to all radial elements 11r depending on the shape of the character, figure, or symbol depicted in the display object 10. In other words, in the portions where the protrusions 11 are close to each other and densely packed due to the shape of the depicted character, figure, or symbol, and the strength of the protrusions 11 can be ensured, the shape is already such that collapse is unlikely to occur, and the force applied during polishing is distributed, so the above-mentioned setting does not necessarily need to be applied.

[0034] In the present invention, as described above, the top surface of the protrusion 11 forms a contour line, thereby depicting a character, figure, or symbol. In the mold for forming such an indicia 10, a recessed portion corresponding to the protrusion 11 and a protrusion corresponding to the portion surrounded by the contour line (the protrusion 11) (the surface of the sidewall portion 2) are provided. In this case, if the width of the portion surrounded by the contour line (the protrusion 11) in the molded indicia 10 is too small, it becomes difficult to properly depict the intended character, figure, or symbol. In addition, if the protrusion for molding in the portion surrounded by the contour line becomes fine, there is a risk of a problem occurring in the white letter targeted by the present invention in which the mold (protrusion) breaks through the cover rubber layer covering the surface of the different color rubber layer (white rubber layer). From this viewpoint, in the present invention, the minimum width of the portion surrounded by the contour line formed by the protrusion 11 is preferably 2.0 mm or more, more preferably 2.5 mm to 3.5 mm.

[0035] The present invention will be further described below with reference to examples, but the scope of the present invention is not limited to these examples. EXAMPLES

[0036] Tires were produced as Conventional Example 1, Comparative Examples 1-2, and Examples 1-4, each having a tire size of 225 / 60R17 99T and a basic structure (cross-sectional structure) as illustrated in FIG. 1. With regard to the structure of the object, the Wr of the top surface of the radial element, the width Wc of the top surface of the circumferential element, and the ratio Wr / Wc thereof were set as shown in Table 1.

[0037] In all cases, the process of polishing the surface of the display object (convex portion) was carried out by mounting each tire on a wheel with a rim size of 17 x 6.5, inflating it to an internal pressure of 200 kPa, and then mounting it on a dedicated polishing machine (buffing machine).

[0038] The surface condition of the markings and the amount of rubber used for these pneumatic tires were evaluated by the following evaluation methods. The results are shown in Table 1.

[0039] Surface condition of the display The surface condition of the markings formed on each tire was visually inspected. The evaluation results were rated as "good" if the surface of the markings (the tops of the protrusions) was smooth, and "poor" if the surface of the markings was not smooth (having a hill in the middle or being worn down on one side) or had fine scale-like irregularities on the surface of the markings.

[0040] Amount of rubber used The amount (volume) of rubber used in the markings formed on each tire was calculated based on the measured dimensions, etc. The evaluation results are shown as an index with Conventional Example 1 being 100. The smaller the index value, the less rubber was used.

[0041] [Table 1]

[0042] As is clear from Table 1, the tires of Examples 1 to 4 were able to improve the surface condition of the indicia while suppressing an increase in the amount of rubber used, compared to Conventional Example 1. On the other hand, in Comparative Example 1, the ratio Wr / Wc was small, so the surface condition of the indicia could not be sufficiently improved. In Comparative Example 2, the width Wr of the top face of the radial element was smaller than the width Wc of the top face of the circumferential element, so the surface condition of the indicia could not be sufficiently improved.

[0043] The present disclosure includes the following inventions. Invention [1] A tire comprising a tread portion extending in a circumferential direction of the tire and forming an annular shape, and a pair of sidewall portions disposed on both sides of the tread portion, wherein an indicia depicting the outline of a letter, figure, or symbol is formed on the outer surface of the sidewall portion by the shape of the top surface of a protrusion protruding from the outer surface of the sidewall portion, and at least a part of the top surface of the protrusion has a different color from the outer surface of the sidewall portion by exposing a different color rubber embedded in a part of the sidewall portion, A tire characterized in that, when a portion of the protrusion constituting the indicia extending along the tire radial direction is defined as a radial element, and a portion of the protrusion constituting the indicia extending along the tire circumferential direction is defined as a circumferential element, a width Wr of a top face of the radial element and a width Wc of a top face of the circumferential element satisfy the relationship Wr / Wc≧1.2. Invention [2] The tire according to invention [1], characterized in that the width Wr of the top surface of the radial element is 2.5 mm or more. Invention [3] The tire according to invention [1] or [2], characterized in that the width Wc of the top surface of the circumferential element is 2.0 mm or less. Invention [4] The tire according to any one of inventions [1] to [3], characterized in that the angle that the radial element forms with respect to the tire radial direction is within the range of ±30°. Invention [5] A tire according to any one of inventions [1] to [4], characterized in that the angle θr that the side of the protrusion makes with the normal direction to the outer surface of the sidewall portion in a cross section perpendicular to the radial element is greater than the angle θc that the side of the protrusion makes with the normal direction to the outer surface of the sidewall portion in a cross section perpendicular to the circumferential element. Invention [6] A tire according to any one of inventions [1] to [5], characterized in that in a cross section perpendicular to the radial elements, a side surface of the protrusion and an outer surface of the sidewall portion are smoothly connected via an arc-shaped connecting portion, and in a cross section perpendicular to the circumferential elements, a side surface of the protrusion and an outer surface of the sidewall portion are smoothly connected via an arc-shaped connecting portion, and a radius of curvature Rr of the connecting portion in the radial elements is larger than a radius of curvature Rc of the connecting portion in the circumferential elements. Invention [7] The tire according to any one of inventions [1] to [6], wherein the minimum width of a portion surrounded by a contour line constituting the convex portion is 2.0 mm or more. Invention [8] The tire according to any one of inventions [1] to [7], wherein the length L of the indicia along the tire radial direction is 25 mm or less. [Explanation of symbols]

[0044] 1 Tread section 2 Sidewall 3 Bead section 4 Carcass layer 5 Bead Core 6 Bead Filler 7 Belt layer 8 Belt reinforcement layer 10 Display items 11 Convex 11r radial element 11c Circumferential element 12 Different Rubber 13 Cover rubber 14 Connection CL Tire Equator E Ground end

Claims

1. A tire comprising a tread portion extending in a circumferential direction of the tire to form an annular shape, and a pair of sidewall portions disposed on both sides of the tread portion, wherein an indicia depicting the outline of a letter, figure or symbol is formed on an outer surface of the sidewall portion by the shape of the top surface of a protrusion protruding from the outer surface of the sidewall portion, and at least a part of the top surface of the protrusion has a different color from the outer surface of the sidewall portion by exposing a different color rubber embedded in a part of the sidewall portion, When a portion of the protrusion constituting the display object extending along the tire radial direction is defined as a radial element, and a portion of the protrusion constituting the display object extending along the tire circumferential direction is defined as a circumferential element, a width Wr of a top surface of the radial element and a width Wc of a top surface of the circumferential element satisfy a relationship of Wr / Wc≧1.

2.

2. 2. The tire according to claim 1, wherein the width Wr of the top surface of the radial element is 2.5 mm or more.

3. The tire according to claim 1 or 2, wherein a width Wc of the top surface of the circumferential element is 2.0 mm or less.

4. 3. The tire according to claim 1, wherein an angle formed by the radial element with respect to the tire radial direction is within a range of ±30°.

5. The tire according to claim 1 or 2, characterized in that an angle θr that the side surface of the protrusion makes with a normal direction to the outer surface of the sidewall portion in a cross section perpendicular to the radial element is larger than an angle θc that the side surface of the protrusion makes with a normal direction to the outer surface of the sidewall portion in a cross section perpendicular to the circumferential element.

6. 3. The tire according to claim 1, wherein in a cross section perpendicular to the radial element, a side surface of the protrusion and an outer surface of the sidewall portion are smoothly connected via an arc-shaped connecting portion, and in a cross section perpendicular to the circumferential element, a side surface of the protrusion and an outer surface of the sidewall portion are smoothly connected via an arc-shaped connecting portion, and a radius of curvature Rr of the connecting portion in the radial element is larger than a radius of curvature Rc of the connecting portion in the circumferential element.

7. The tire according to claim 1 or 2, characterized in that a minimum width of a portion surrounded by a contour line constituting the protruding portion is 2.0 mm or more.

8. 3. The tire according to claim 1, wherein the length L of the indicia in the tire radial direction is 25 mm or less.

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