JP2008201384A - Pneumatic tire - Google Patents

Abstract

The present invention provides a pneumatic tire that is excellent in visibility of a mark displayed on a sidewall surface and can maintain the effect of improving the visibility for a long period of time.
In a pneumatic tire 1 in which a mark 12 is provided on a side wall 3, a mark region 10 including the mark 12 and a background portion 11 of the mark 12 has a tire axial direction from the side wall surface. A concave surface is formed on the inside, and a mark 12 is formed in the mark region 10 with a convex surface projecting from the concave surface, and the surface of the mark 12 has an arithmetic average roughness (Ra) of 0.4 to 0.4. It consists of a mirror surface part having a surface roughness of 1.5 μm, and the background part 11 consists of a rough surface part exceeding the surface roughness of Ra 1.5 μm.
[Selection] Figure 1

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire excellent in the visibility of marks such as letters, numbers, symbols, or figures provided on a sidewall surface.

  Conventionally, a mark consisting of letters, numbers, symbols indicating the manufacturer name, brand name, tire size, etc., and the shape of the tire rotation direction, design pattern for dressing up the side, etc. on the tire sidewall surface. Is displayed.

  Usually, the mark is displayed by protruding the mark from the sidewall surface. In addition, a decorative body is formed by carving a number of fine grooves called ridges on the surface of the sidewall of the tire, and marks such as characters are displayed on the decorative body. For example, a ridge is engraved only on the character to be the mark, and the mark is displayed using the fact that the reflection of light is different from the background where the ridge is not engraved, and the background surrounding the mark and the mark Different ridges were formed in the part to improve the visibility of the mark (for example, Patent Document 1).

  However, when the mark is composed of the above ridge, if the tire is used for a long period of time, fine dirt such as dust and dirt will accumulate on the groove bottom of the ridge, deteriorating the appearance of the tire and reducing the visibility of the mark. I was letting. Furthermore, it is not easy to clean the dust and dirt accumulated on the bottom of the fine ridge groove, and it also requires complicated work to remove the scale such as the release agent accumulated on the groove bottom on the mold side. It was.

  Further, as for improving the appearance of the tire, the surface roughness is specified to be 1.5 to 20 μm to increase the glossiness of the tire surface (such as Patent Document 2), and the surface roughness is comparatively 5 to 500 μm. Specified in a large range, the light is diffusely reflected on the rough surface portion to make the tire surface color black (Patent Document 3 etc.), and the surface roughness is made extremely small to increase the surface glossiness and added Various techniques have been proposed in the past, such as a technique for improving the appearance by delaying diffusion of the agent to the surface (Patent Document 4).

However, what specifies the surface roughness of the tire is to adjust the molding surface to a specific roughness by injecting abrasive materials such as metal and glass beads onto the molding surface of the tire. Although it is suitable for adjusting the roughness of a wide area, it is possible to make specific parts of sidewalls such as the above-mentioned marks, particularly dense characters and graphic parts, to a specific roughness even if abrasive materials and injection conditions are selected. It was difficult. Further, when the surface roughness is made very small and the glossiness is made large, for example, when the tire comes into contact with a curbstone, it is easy to be noticeable, and conversely, the appearance may be deteriorated.
Japanese Patent Laid-Open No. 11-20416 JP 2000-142026 A JP 2003-252012 A JP 2004-17964 A

  In view of the above-mentioned problems, the present invention is excellent in the visibility of the mark displayed on the sidewall surface, prevents the mark from being attached to dust and dirt, and is less susceptible to trauma. The present invention provides a pneumatic tire capable of maintaining the effect of improving the visibility of a mark for a long period of time by maintaining the appearance of the tire well over a long period of time.

  The present inventor has intensively studied to solve the above problems, and has a mirror surface portion that specifies the surface roughness in the mark display region on the side surface of the tire, and devise the arrangement height in the tire axial direction. It has been found that the above problems can be solved.

  That is, according to the present invention, in a pneumatic tire in which a mark is provided on a sidewall, a mark region including the mark and a background portion of the mark is formed as a concave surface on the inner side in the tire axial direction from the sidewall surface. The pneumatic tire is characterized in that a mirror surface portion having a surface roughness of arithmetic mean roughness (Ra) of 0.4 to 1.5 μm is provided in at least a part of the mark region.

  In the pneumatic tire of the present invention, it is preferable that the surface of the mark is composed of the mirror surface portion, and the background portion of the mark is composed of a rough surface portion exceeding a surface roughness of Ra 1.5 μm.

  Moreover, the pneumatic tire of the present invention can be formed of a convex surface protruding from a mark region where the mark forms the concave surface.

  In the pneumatic tire of the present invention, the background portion of the mark may be a mirror surface portion, and the surface of the mark may be a rough surface portion having a surface roughness of Ra 1.5 μm.

  Also in this case, the mark portion can be formed by a convex surface protruding from the mark area forming the concave surface.

  Furthermore, in the pneumatic tire of the present invention, it is preferable that the difference in Ra between the mirror surface portion and the rough surface portion is 1 μm or more.

  According to the pneumatic tire of the present invention, the difference between the mark displayed on the sidewall and the glossiness of the background portion makes the mark stand out and has excellent visibility. Prevent dust and dirt from sticking, make it less susceptible to trauma, improve ozone resistance and maintain the tire's appearance for a long time, and maintain the effect of improving the visibility of the mark for a long time Can do. In addition, maintenance such as polishing of the molding surface of the mold is easy, and tire productivity and maintenance efficiency can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view of a tire half cross section showing a sidewall surface of a pneumatic tire T1 (hereinafter, the pneumatic tire may be simply referred to as “tire”) according to the first embodiment of the present invention. 2 (a) to (e) are cross-sectional views taken along line XX in FIG. In FIGS. 2A to 2E, the aspect of the sidewall surface is shown in a flat plane for convenience.

  The tire T1 includes a tread portion 2, a sidewall 3 extending outward in the tire radial direction from both ends, and a bead portion 4 connected to the outer end of the sidewall 3 and fixed to a rim flange. A radial structure carcass 6 with the carcass ply end folded back and locked around the bead core 5, a belt layer 7 disposed on the outer periphery of the tread portion 2 of the carcass 6, and a belt reinforcing layer wound around the outer periphery of the belt layer 7 A passenger car radial tire having 8 is illustrated.

  On the surface of the sidewall 3 of the tire T1, there is a mark 12 made up of characters, numbers, symbols indicating the manufacturer name, brand name, tire size, and the like, such as the rotation direction of the tire, and a design pattern for dressing up the side. Is displayed. In FIG. 1, the mark 12 shows a character string (TOYO) as an engraved character.

  Around the mark 12, a background portion 11 made of a solid surface is provided as a background for enhancing the visibility of the mark 12, and a mark region 10 is formed by the mark 12 and the background portion 11. Yes.

  In the tire T <b> 1, the mark region 10 is formed of a concave plane that is recessed inward in the tire axial direction from the surface 3 a of the sidewall 3.

  Although the depth L in the tire axial direction and the width W in the tire radial direction with respect to the sidewall surface 3a of the mark region 10 are not particularly limited, for example, the depth L is about 0.5 to 3.0 mm. As the width W, about 4 to 40 mm is shown as a preferable range (see FIG. 2A).

  If the depth L is less than 0.5 mm, scratches are likely to be caused when contacting the curbstone, and if it exceeds 3.0 mm, stress during running concentrates on the bottom edge of the concave surface, and cracks are likely to occur. In addition, if the width W is less than 4 mm, the width of the mark area 10 is narrowed, and the area of the mark portion is inevitably reduced, so that it is difficult to obtain the effect of improving the visibility. It becomes easy to receive, and the appearance is deteriorated.

  In the tire T1, the surface portion 12a of the mark 12 is made of a mirror surface having an arithmetic average roughness (Ra) of 0.4 to 1.5 μm, and the background portion 11 has an Ra of 1.5 μm. It is composed of a rough surface exceeding the surface roughness.

  As a result, the light reflectivity differs depending on the difference in glossiness between the mirror-finished mark surface 12a and the rough background surface 11a, and the visibility of the mark 12 is improved by conspicuous. be able to.

  Ra of the mirror surface portion is set in a range of 0.4 to 1.5 μm. When Ra is less than 0.4 μm, the light reflectivity of the mark surface 12a is increased, and the glare tends to be white. On the contrary, the visibility of the mark 12 may be reduced, and if mud, oil or the like adheres to the surface, cleaning becomes easier, but small trauma such as rubbing with the curb tends to be noticeable. Furthermore, a special surface treatment (for example, plating treatment of chromium or the like) is required for the tire molding die, which is not preferable because the tire manufacturing cost increases. On the other hand, when Ra exceeds 1.5 μm, fine dust such as dust and dirt such as oil enter the fine irregularities on the surface, and the cleaning property is deteriorated and the dirt is not removed forever and the appearance is deteriorated.

  Moreover, it is preferable that the difference of Ra of the surface 12a which consists of the said mirror surface, and the background part surface 11a which consists of rough surfaces is 1 micrometer or more. When this difference is 1 μm or more, a remarkable difference is obtained in the glossiness between the two, and the visibility of the mark 12 can be effectively enhanced.

  The upper limit of Ra of the rough surface portion is not particularly limited, but is preferably less than 2 μm. When Ra is 2 μm or more, the surface becomes textured, and the rubber surface becomes uneven, whereby dust and the like are likely to adhere, and ozone resistance is disadvantageous, and ozone cracks are likely to occur due to long-term use.

  The surface roughness (Ra) is the degree of surface unevenness of the area per unit length measured in accordance with JIS B0601 (stylus type surface roughness measuring instrument) using a stylus type surface roughness meter. Is the arithmetic average roughness.

  Ra of the mark area 10 can be formed by a tire vulcanization mold having a molding surface having a surface roughness substantially equal to the roughness of the tire surface. That is, the surface roughness of the mold is transferred to the outer surface of the tire by vulcanization molding with substantially the same surface roughness.

  The surface roughness of the mold forming surface can be adjusted by using a known method such as a shot blasting method or a mirror polishing method.

  The tire T1 of the present invention may be formed of a convex surface protruding in the surface of the mark area 10 where the mark 12 portion is recessed from the sidewall surface. Alternatively, the mark 12 and the background portion 11 may be formed by partitioning a mirror surface and a rough surface in the mark area 10 on the same plane.

  In the example shown in FIG. 2A, the mark region 10 is formed of a concave plane that is recessed inward in the tire axial direction from the surface of the sidewall 3, and the mark 12 (the vertical cross-section portion of the letter “O”) is It is formed of a convex surface projecting with respect to the background portion 11, and its surface 12a is made of a mirror surface portion having a surface roughness of Ra 0.4 to 1.5 μm. The background portion 11 has a surface roughness of Ra of 1.5 μm. It consists of a rough surface part exceeding.

  The protruding height of the mark 12 is preferably provided on the inner side in the tire axial direction with respect to the sidewall surface 3a, and the mark surface 12a can be hardly damaged. The protruding height in this case is preferably about 20 to 80% of the concave surface depth L.

  According to the above configuration, by making the mark 12 a relief character, the gloss of the mark surface 12a made of a mirror surface is made to appear in the mark area 10 made of a rough surface so that the mark 12 can be seen. It is possible to enhance the visibility.

  In the example shown in FIG. 2B, the mark 12 and the background portion 11 are formed in the mark area 10 in the same plane. The surface of the mark 12 is a mirror surface 12a and the background portion 11 is formed. The surface is formed with a rough surface and partitioned, and cracks due to stress concentration do not occur at the rising edge of the protruding portion when the mark 12 protrudes from the mark region 10.

  In the example shown in FIG. 2C, the mark 12 and the background portion 11 are formed in the mark area 10 in the same plane. The surface of the mark 12 is a mirror surface 12a and the background portion 11 is formed. The surface of the mark is formed with a rough surface, and a narrow groove 13 is provided around the mark 12 (characters) to divide both of them. Thus, the background portion 11 made of a rough surface can be further enhanced.

  In the example shown in FIG. 2D, the mark 12 and the background portion 11 are formed in the mark area 10 in the same plane. The surface of the mark 12 is a mirror surface 12a and the background portion 11 is formed. The surface is formed with a rough surface, and protrusions 14 are provided around the mark 12 (characters) to divide the two, and there are the same effects as in FIG. Can protect the mark area 10 and improve the trauma resistance.

  In the example shown in FIG. 2 (e), the mark region 10 is formed of a concave plane that is recessed inward in the tire axial direction from the surface of the sidewall 3, and the mark 12 is further recessed with respect to the background portion 11. The surface portion 12a is a mirror surface, and the background portion 11 is a rough surface.

  According to this configuration, by making the mark 12 a sinking character, the glossiness of the surface 12a made of a mirror surface is submerged in the mark area 10 made of a rough surface, giving a bottoming impression. The visibility of the mark 12 is improved and the mark surface 12 is less susceptible to trauma. Furthermore, since the molding surface for forming the mark surface 12a is a convex surface, the mirror polishing operation is easy.

  The character string “TOYO” shown in the present example is a solid character with no border at the character peripheral portion, but may be a character with a border.

[Second Embodiment]
3 is a perspective view of a tire judgment surface showing a sidewall surface of a tire T2 according to a second embodiment of the present invention, and FIGS. 4 (a) to 4 (e) are cross-sectional views taken along line YY in FIG. It is. 4A to 4E, the side surfaces of the sidewalls are developed in a plane for convenience.

  The tire T2 is a radial tire for passenger cars having the same internal structure as the tire T1 (the same part as the tire T1 and the same reference numerals are assigned to the same members), and the name of the manufacturer is provided on the surface of the sidewall 3 of the tire T2. Marks 22 such as letters, numbers and symbols indicating brand names, tire sizes, and the like, tire rotation directions, and design figures for side dressing are displayed. In FIG. 3, the mark 22 shows a character string (TOYO) as an engraved character.

  Around the mark 22, a background portion 11 is provided as a background for enhancing the visibility of the mark 22, and the mark 22 and the background portion 11 form a mark area 20.

  In the tire T <b> 2, the mark region 20 is formed of a concave plane that is recessed inward in the tire axial direction from the surface 3 a of the sidewall 3.

  The depth L in the tire axial direction and the width W in the tire radial direction with respect to the sidewall surface 3a of the mark region 20 are not particularly limited. For example, as the depth L, as in the first embodiment, About 0.5 to 3.0 mm and a width W of about 4 to 40 mm are shown as preferable ranges (see FIG. 4A), and the reason is the same.

  In the tire T2, the surface portion 22a of the mark 22 has a rough surface where Ra exceeds a surface roughness of 1.5 μm, and the background portion 21 of the mark 22 has a surface roughness of Ra 0.4 to 1.5 μm. It has a mirror surface.

  As a result, the light reflectivity differs depending on the difference in gloss between the mirror surface of the background portion 21a and the rough mark surface 22a. By giving the background portion 21 gloss, Thus, the mark 22 appears to be lifted, and the visibility can be improved.

  Ra of the said mirror surface part is the range of 0.4-1.5 micrometers. When Ra is less than 0.4 μm, it becomes easy to wash when mud, oil, or the like adheres to the background surface 21a, but it is easy to receive a small external damage due to rubbing with a curb or the like, and the damage becomes conspicuous. Furthermore, a special surface treatment (for example, plating treatment of chromium or the like) is required for the tire molding die, which is not preferable because the tire manufacturing cost increases. On the other hand, when Ra exceeds 1.5 μm, fine dust such as dust and dirt such as oil enter the fine irregularities on the surface, and the cleaning property is deteriorated and the dirt is not removed forever and the appearance is deteriorated.

  Further, the difference in Ra between the rough marking surface 22a and the mirror background surface 21a is preferably 1 μm or more. When this difference is 1 μm or more, a remarkable difference is obtained in the glossiness between the two, and the visibility of the mark 22 can be enhanced.

  Ra of the mark area 20 can be formed by a tire vulcanization mold having a molding surface having a surface roughness substantially equal to the roughness of the tire surface. That is, the surface roughness of the mold is transferred to the outer surface of the tire by vulcanization molding with substantially the same surface roughness.

  The surface roughness of the mold forming surface can be adjusted by using a known method such as a shot blasting method or a mirror polishing method.

  Further, since the background portion 21 is formed on a convex surface on the tire mold side, it is easy to polish the mold surface, and for removing scale such as a release agent deposited on the mold surface through tire vulcanization molding. Maintenance such as re-grinding is easy, and tire productivity and maintenance efficiency can be improved.

  The tire T2 of the present invention may be formed of a convex surface protruding in the surface of the mark region 20 where the mark 22 portion is recessed from the sidewall surface. Alternatively, the mark 22 and the background portion 21 may be divided and formed by a mirror surface and a rough surface in the mark area 20 on the same plane.

  In the example shown in FIG. 4A, the mark region 20 is formed by a concave plane that is recessed inward in the tire axial direction from the surface 3 a of the sidewall 3, and the mark 22 (longitudinal section of the letter “O”). Is formed of a convex surface projecting with respect to the background portion 21, the surface portion 22 a is made of a rough surface portion having a surface roughness Ra exceeding 1.5 μm, and the background portion 21 has a Ra of 0.4 to 1.. It consists of a 5 μm mirror.

  However, the protruding height of the mark 22 is preferably provided on the inner side in the tire axial direction with respect to the sidewall surface 3a, so that the mark surface 22a can be hardly damaged. The protruding height in this case is preferably about 20 to 80% of the concave surface depth L.

  According to the above configuration, by using the mark 22 as the embossed character, the mark surface 22a made of a rough surface can be raised in the mark area 20 made of a glossy mirror surface and be made to stand out. In addition, the scenery around the tire is projected on the background portion 21 and the effect of further improving the tire appearance is expected.

  In the example shown in FIG. 4B, the mark 22 and the background portion 21 are formed in the mark area 20 in the same plane, and the surface of the mark 22 is a rough surface 22a and the background portion. The surface of 21 is formed with a mirror surface and is partitioned, and cracks due to stress concentration do not occur at the rising edge of the protruding portion when the mark 22 protrudes from the mark region 20.

  In the example shown in FIG. 4C, the mark 22 and the background portion 21 are formed in the mark area 20 in the same plane, and the surface of the mark 22 is a rough surface 22a and the background portion. The surface of 21 is formed as a mirror surface, and a narrow groove 23 is provided around the mark 22 (character) to divide both, and the mark surface 22a made of a rough surface passes through the shadow of the narrow groove 23, The mark 22 can be emphasized by appearing to be raised with respect to the background portion 21 made of a mirror surface.

  In the example shown in FIG. 4D, the mark 22 and the background portion 21 are formed in the mark area 20 in the same plane, and the surface of the mark 22 is a rough surface 22a and the background portion. The surface of 21 is formed as a mirror surface, and a ridge 24 is provided around the mark 22 (character) to divide both of them. The effect is the same as in the case of FIG. However, it can protect the mark area 20 and improve the trauma resistance.

  In the example shown in FIG. 4 (e), the mark region 20 is formed by a concave plane that is recessed inward in the tire axial direction from the surface of the sidewall 3, and the mark 22 is further recessed with respect to the background portion 21. The surface portion 22a is a rough surface, and the background portion 21 is a mirror surface.

  According to the above configuration, by using the mark 22 as the engraved character, the rough mark surface 22a is submerged in the mirror mark area 20 to give a deep impression and the background portion 21 The glossiness is emphasized, the visibility of the mark 22 is improved, and the mark surface 22a is less likely to be damaged.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the examples.

  A rubber composition for sidewalls having the following formulation was kneaded and prepared by a conventional method using a Banbury mixer with a capacity of 200 liters.

[Rubber composition for sidewall]
・ Natural rubber (50 parts by weight: RSS # 3 made in Thailand) ・ Butadiene rubber (50 parts by weight: Ube Industries, Ltd. BR150B) ・ Carbon black FEF (60 parts by weight: Tokai Carbon Co., Ltd. Seest SO) ・ Aroma oil ( 10 parts by weight: Japan Energy Co., Ltd. X-140), paraffin wax (2 parts by weight: Nippon Seiwa Co., Ltd. OZOACE-0355), anti-aging agent 6C (2 parts by weight: Ouchi Shinsei Chemical Co., Ltd. Nocrack) 6C), stearic acid (2 parts by weight: Kao Corp. Lunac S-20), zinc oxide (3 parts by weight: Mitsui Kinzoku Co., Ltd., Zinc Hua 1), sulfur (2 parts by weight: Hosoi Chemical Co., Ltd.) ) 5% oil-treated powder sulfur) ・ Vulcanization accelerator NS (1.5 parts by weight: Ouchi Shinsei Chemical Co., Ltd. Noxeller NS-P)

  A radial tire having a size of 225 / 45R17, in which the obtained rubber composition was applied to the sidewall portion, was prototyped. The prototype tire uses a steel sidewall mold, and the surface roughness of the marking area molding surface of the sidewall is adjusted to a predetermined range by a known shot blasting method or mirror polishing method. Each prototype tire was vulcanized and molded under the same vulcanization conditions. The mark area is composed of a mark character and a plain or ridge background as shown in FIG.

  Example 1 and Comparative Examples 1, 2, and 4 have the mark area cross section shown in FIG. 2A, and Example 2 has the mark region cross section shown in FIG. 4A. And a triangular section ridge extending in parallel and linearly with a crest interval of 2.5 mm in the background and inclined at an angle of 20 degrees with respect to the tire radial direction, and provided in the mark area. In the tire of Comparative Example 3, the mark region was provided on the plane of the sidewall surface, and the character of the mark was protruded from the sidewall surface.

  The surface roughness Ra of the mark area of the prototype tire is measured by the following method, and then the visibility of the mark, after running the actual tire, after contacting the curb, and after running the ozone irradiation drum by the following method. evaluated. The results are shown in Table 1.

[Surface roughness Ra]
In accordance with the method of JIS B0601, the arithmetic average surface roughness Ra of the mark portion and the background portion of the prototype tire was measured using a stylus type surface roughness meter “E-35A” manufactured by Tokyo Seimitsu Co., Ltd. .

[Visibility of mark]
The tire sidewalls were visually observed by 10 panelists. The visibility of the mark was sensory-evaluated by a five-point method, and the average of the results was rounded to the nearest five and shown in Table 1 as an integer. The larger the value, the better.

[Appearance after running the vehicle]
Visually observe the appearance of the mark area after a prototype tire is assembled with a JIS-defined rim (internal pressure 220 kPa), mounted on a domestic passenger car with a displacement of 2500 cc, and running on a 3000 km actual road on a dry asphalt road. Then, sensory evaluation was performed by a five-point method. The larger the value, the better.

[Appearance after curb contact]
The prototype tire is assembled with a JIS stip rim (internal pressure 220 kPa) and mounted on a domestic passenger car with a displacement of 2500 cc. The front tire is brought into contact with a concrete curb at a speed of 5 km / h and an entrance angle of 5 degrees. After that, the appearance of the mark area when moving 50 cm was visually observed, and sensory evaluation was performed by a five-point method. The larger the value, the better.

[Appearance after running the ozone irradiation drum]
Trial tire is assembled with JIS specified rim (internal pressure 220 kPa), JIS maximum load is applied, ozone concentration is 80 pphm and temperature is 38 ° C, using drum tester at 30 km / h for 3 weeks After running, the state of ozone crack generation in the mark area was visually observed and evaluated by a five-point method. The larger the value, the better.

  As shown in the results of Table 1, the tires of Examples 1 and 2 according to the present invention are not only excellent in the visibility of the mark, but also are difficult to get dirt due to running the vehicle in the mark area, Ozone crack resistance can be improved by making the surface roughness smaller than that of conventional satin (Comparative Example 1). It can be seen that can be maintained well over a long period of time.

  The present invention can be applied to pneumatic tires for various sizes and uses such as for passenger cars, light trucks, large tires for buses and trucks.

It is a perspective view of the tire half section of a 1st embodiment. It is sectional drawing in the XX line of FIG. It is a perspective view of the tire half section of a 2nd embodiment. It is sectional drawing in the YY line of FIG.

Explanation of symbols

T1 …… Pneumatic tire 2 …… Tread part 3 …… Side wall 4 …… Bead part 5 …… Bead core 6 …… Carcass 7 …… Belt 10 …… Mark area 11 …… Background part 12 …… Mark

Claims (6)

In a pneumatic tire with a mark on the sidewall,
A mark region including the mark and a background portion of the mark is formed as a concave surface in the tire axial direction from the sidewall surface,
A pneumatic tire characterized in that a mirror surface portion having a surface roughness of an arithmetic average roughness (Ra) of 0.4 to 1.5 μm is provided in at least a part of the mark region. The pneumatic tire according to claim 1, wherein the surface of the mark is made of the mirror surface portion, and the background portion of the mark is made of a rough surface portion having a surface roughness of Ra 1.5 μm. The pneumatic tire according to claim 2, wherein the mark is formed by a convex surface protruding from a mark region forming the concave surface. 2. The pneumatic tire according to claim 1, wherein a background portion of the mark is made of the mirror surface portion, and a surface of the mark is made of a rough surface portion exceeding a surface roughness of Ra 1.5 μm. The pneumatic tire according to claim 4, wherein the mark portion is formed by a convex surface protruding from a mark region forming the concave surface. The pneumatic tire according to claim 1, wherein a difference in Ra between the mirror surface portion and the rough surface portion is 1 μm or more.

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