Pneumatic tire

Abstract

To provide a pneumatic tire capable of improving low fuel consumption by suppressing air resistance during traveling while securing a decorative effect by serrations.SOLUTION: Serrations 30 having ridges 31 arranged thereon are formed in an outer peripheral region that is located in the outer side in a tire radial direction of the maximum tire width position on an outer surface of at least one of a pair of sidewall portions, and the serrations 30 are arranged in recessed portions 50 that are recessed inward in a tire axial direction from a profile surface PF of the sidewall portion, and protrude from the profile surface PF at protrusion height Ph of 0.1 mm or less.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires.

Background Art

[0002] In recent years, due to environmental issues and the increasing interest in the EV (Electric Vehicle) shift, there has been an increasing demand for improving the low fuel consumption of tires. The low fuel consumption of tires is affected not only by rolling resistance but also by air resistance during driving. From the perspective of suppressing air resistance, it is preferable that the outer surface of the sidewall portion is formed smoothly.

[0003] On the other hand, a design including a serration with ridges arranged may be given to the outer surface of the sidewall portion. The serration produces a shadow due to its unevenness and exhibits a decorative effect of improving the appearance of the tire. Therefore, a tire that can suppress air resistance during driving and improve low fuel consumption while ensuring the decorative effect of the serration is desired.

[0004] Patent Documents 1 and 2 describe pneumatic tires having serrations formed on the outer surface of the sidewall portion, respectively.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the tire described in Patent Document 1, the deepest part of the serration is located on the virtual outer surface of the tire or outside the tire in the axial direction. According to such a configuration, since the serration protrudes greatly from the profile surface of the sidewall portion, the air resistance tends to increase.

[0007] In the tire described in Patent Document 2, the serration is arranged in a recess formed on the outer surface of the sidewall portion, and the height of the ridge is smaller than the depth of the recess. According to such a configuration, although the ridge does not protrude from the profile surface, a recess having a depth larger than the height of the ridge is inevitably provided, so that a relatively large undulation is formed. As a result, a large air vortex is likely to be generated during running, and air separation occurs at or near the serration, increasing the pressure resistance. Therefore, it is considered that the effect of suppressing air resistance is not sufficient.

[0008] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire capable of suppressing air resistance during running and improving fuel efficiency while ensuring a decorative effect by serrations.

Means for Solving the Problems

[0009] The pneumatic tire of the present disclosure includes a pair of sidewall portions, and serrations in which ridges are arranged are formed in an outer peripheral side region outside the tire in the radial direction from the maximum width position of the tire on at least one of the outer surfaces of the pair of sidewall portions. The serration is arranged in a recess recessed inward in the axial direction of the tire from the profile surface of the sidewall portion and protrudes with a protrusion height of 0.1 mm or less from the profile surface.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0011] Embodiments of the pneumatic tire of the present disclosure will be described with reference to the drawings.

[0012] FIG. 1 is a cross-sectional view schematically showing the pneumatic tire T of the present embodiment. The cross-sectional view shows a cross-section cut along a plane including the central axis of the tire, that is, a tire meridian cross-section. The tire T is a pneumatic tire for automobiles including a pair of bead portions 1, a pair of sidewall portions 2 extending radially outward in the tire diameter direction from the bead portions 1, and a tread portion 3 connected to each outer end in the tire diameter direction of the sidewall portions 2. The tire T is preferably a pneumatic tire for passenger cars, but may also be a tire of other categories.

[0013] An annular bead core 1a is embedded in the bead portion 1. The bead core 1a is formed by covering a converging body such as a steel wire with rubber. A bead filler 1b is disposed on the outer side in the tire diameter direction of the bead core 1a. The bead filler 1b is formed of rubber having a triangular cross-section extending radially outward in the tire diameter direction from the bead core 1a.

[0014] Here, the tire radial direction is the direction along the diameter of the tire T and corresponds to the vertical direction in FIG. 1. In FIG. 1, the upper side is the outside in the tire radial direction, and the lower side is the inside in the tire radial direction. The tire axial direction is the direction parallel to the rotation axis of the tire T and corresponds to the left-right direction in FIG. 1. The inner side in the tire axial direction is the side approaching the tire equator line (not shown) and corresponds to the left side in FIG. 1. The outer side in the tire axial direction is the side away from the tire equator line and corresponds to the right side in FIG. 1. The tire equator line is located at the center of the tire T in the tire axial direction and is an imaginary line perpendicular to the tire rotation axis in a plan view. The tire circumferential direction is the direction around the rotation axis of the tire T.

[0015] The tire T includes a carcass 4 extending in a toroidal shape across between a pair of bead portions 1. The carcass 4 is wound up from the inner side to the outer side in the tire axial direction so as to sandwich the bead core 1a and the bead filler 1b. The carcass 4 is formed by a carcass ply formed by rubber-coating a carcass cord. The carcass cords are aligned in a direction intersecting the tire circumferential direction (for example, a direction forming an angle of 75 to 90 degrees with respect to the tire circumferential direction). As the material of the carcass cord, a metal such as steel or an organic fiber such as polyester, rayon, nylon, or aramid is preferably used.

[0016] The tire T includes a belt 5 laminated on the outer side in the tire radial direction of the carcass 4. The belt 5 is formed by a plurality (two in this embodiment) of belt plies laminated on each other. Each belt ply is formed by rubber-coating a belt cord. The belt cords are aligned in a direction inclined with respect to the tire circumferential direction (for example, a direction forming an angle of 20 to 30 degrees with respect to the tire circumferential direction). As the material of the belt cord, a metal such as steel is preferably used. The plurality of belt plies are laminated such that the belt cords cross each other in opposite directions therebetween.

[0017] Although not adopted in this example, a structure in which a belt reinforcing material is laminated on the outer side in the tire radial direction of the belt 5 may be used. The belt reinforcing material is formed by a belt reinforcing ply formed by rubber-coating a belt reinforcing cord. The belt reinforcing cords are aligned substantially parallel to the tire circumferential direction. The belt reinforcing ply is formed, for example, by spirally winding one or a plurality of rubber-coated belt reinforcing cords along the tire circumferential direction. As the material of the belt reinforcing cord, the above-described organic fiber is preferably used. The belt reinforcing material may be in a form that entirely covers the belt 5, or may be in a form that partially covers the belt 5 (for example, only at both ends).

[0018] On the inner surface of the tire T, an inner liner rubber 6 formed of a rubber excellent in air barrier properties such as butyl rubber is provided. On the outer side in the tire axial direction of the bead core 1a and the bead filler 1b, a rim strip rubber 7 that forms the outer surface of the bead portion 1 is provided. On the outer side in the tire axial direction of the carcass 4, a sidewall rubber 8 that forms the outer surface of the sidewall portion 2 is provided. On the outer side in the tire radial direction of the belt 5, a tread rubber 9 that forms the outer surface of the tread portion 3 is provided. The tread rubber 9 has a tread pattern formed according to required tire performance and usage conditions.

[0019] The tire maximum width position Pm is the position where the profile surface PF of the sidewall portion 2 is farthest from the tire equator line in the tire axial direction. The profile surface PF is a surface that forms the basic contour of the sidewall portion 2 excluding protrusions such as ridges. The profile surface PF is formed by a smooth curved surface that curves convexly outward in the tire axial direction.

[0020] On the outer surface of the sidewall portion 2, the outer peripheral region Ro is a region radially outside the tire in the tire radial direction with respect to the tire maximum width position Pm, and the inner peripheral region Ri is a region radially inside the tire in the tire radial direction with respect to the tire maximum width position Pm. Around the tire during running, the air flowing from the front side to the rear side in the traveling direction contacts the outer peripheral region Ro of the tread portion 3 and the sidewall portion 2, and then tends to peel off in the vicinity of the tire maximum width position Pm. For this reason, in the outer peripheral region Ro, the contribution to the air resistance during running, particularly the pressure resistance, is larger than that in the inner peripheral region Ri.

[0021] The mold parting position Ps is set radially outside the tire in the tire radial direction with respect to the tire maximum width position Pm. The mold parting position Ps is the boundary (division position) between the tread mold for molding the tread portion 3 and the side mold for molding the sidewall portion 2. The mold parting position Ps is identified from the parting line generated on the outer surface of the sidewall portion 2. The parting line is a protruding mold mark generated at the division position. The outer peripheral region Ro is the region between the tire maximum width position Pm and the mold parting position Ps.

[0022] The rim line RL is set radially inside the tire in the tire radial direction with respect to the tire maximum width position Pm. The rim line RL is formed by a protrusion extending annularly along the tire circumferential direction. The rim line RL is used to confirm that the bead portion 1 is correctly mounted on the rim when the tire T is assembled to the wheel. The inner peripheral region Ri is the region between the tire maximum width position Pm and the rim line RL. Although not shown in FIG. 1, in the present embodiment, three circumferential protrusions 41 to 43 protruding outward in the tire axial direction are provided between the mold parting position Ps and the rim line RL.

[0023] FIG. 2 is a view showing a part of the outer surface of the sidewall portion 2, and is a view of the region between the mold parting position Ps and the circumferential protrusion 43 as seen from the outer side in the tire axial direction. FIG. 3 is an enlarged view showing the main part of FIG. 2. FIG. 4 is a cross-sectional view taken along the line X-X of FIG. 3, and shows a cross-section along a direction orthogonal to the extending direction of the ridge 31. FIG. 5 is a cross-sectional view taken along the line Y-Y of FIG. 3, and shows a cross-section along a direction parallel to the extending direction of the ridge 31.

[0024] As shown in FIGS. 2 to 5, in this tire T, a serration 30 in which ridges 31 are arranged is formed in the outer peripheral side region Ro on the outer side in the tire radial direction with respect to the tire maximum width position Pm on at least one of the outer surfaces of the pair of sidewall portions 2. The serration 30 is disposed in a recess 50 that is recessed inward in the tire axial direction from the profile surface PF of the sidewall portion 2, and protrudes with a protrusion height Ph of 0.1 mm or less from the profile surface PF.

[0025] In the present embodiment, a part of the serration 30 is disposed in the inner peripheral side region Ri. In a single serration 30, the area of the portion disposed in the outer peripheral side region Ro is larger than the area of the portion disposed in the inner peripheral side region Ri. However, the present invention is not limited to this, and all of the serration 30 may be disposed in the outer peripheral side region Ro.

[0026] The recess 50 has a depth D50 with respect to the profile surface PF. The ridge 31 bulges outward in the tire axial direction from the bottom surface of the recess 50. The ridge 31 has a height H31 from the bottom to the top connected to the bottom surface of the recess 50. The height H31 is set to be substantially constant along the extending direction of the ridge 31. The height H31 of the ridge 31 is larger than the depth D50 of the recess 50 (i.e., H31 > D50), and the difference therebetween corresponds to the protrusion height Ph. The protrusion height Ph is the height of the serration 30 (the ridge 31 forming the serration 30) with respect to the profile surface PF.

[0027] In the serration 30, the unevenness associated with the ridge 31 creates a shadow of the color (black) of the sidewall rubber 8, thereby achieving a decorative effect. Since the shadow becomes thinner as the height H31 becomes smaller, it is effective to ensure the height H31 of the ridge 31 in order to ensure the decorative effect. In this tire T, since the serration 30 is arranged in the recess 50, the height H31 can be ensured without significantly protruding the ridge 31 from the profile surface PF, and it is easy to ensure the decorative effect by the serration 30.

[0028] In this tire T, although the serration 30 protrudes from the profile surface PF, the protruding height Ph is slight, specifically 0.1 mm or less. Therefore, compared with a form in which the serration protrudes significantly from the profile surface, the air resistance during running can be suppressed. Further, as described with reference to FIGS. 6 and 7, the structure in which the serration 30 protrudes slightly is also effective in suppressing the air resistance during running as compared with a structure in which the serration does not protrude from the profile surface (a comparative example described later). Therefore, according to this tire T, while ensuring the decorative effect by the serration 30, the air resistance during running can be suppressed to improve fuel efficiency.

[0029] FIG. 6 shows the serration 30c in the comparative example. The serration 30c is arranged in the recess 50c recessed from the profile surface PF and does not protrude from the profile surface PF. FIG. 7 shows the serration 30 in the present embodiment. As described above, the serration 30 is arranged in the recess 50 recessed from the profile surface PF and slightly protrudes from the profile surface PF. FIGS. 6 and 7 respectively show (A) a cross-sectional view along a direction orthogonal to the extending direction of the ridge, (B) a perspective view, and (C) a cross-sectional view along a direction parallel to the extending direction of the ridge.

[0030] In Figures 6 and 7, the air flow is shown diagrammatically with arrows. Around the tire when it is moving, air flows from the front to the rear in the direction of travel, and the orientation of the ridges relative to that direction of travel changes as the tire rolls, so the situation is divided into two: when the air flows perpendicular to the direction of extension of the ridges, and when the air flows parallel to the direction of extension of the ridges. The behavior of the air in the former case is shown in (A), and the behavior of the air in the latter case is shown in (B) and (C).

[0031] From the viewpoint of ensuring a decorative effect, the ridge 31c of the comparative example is set to a height equivalent to that of the ridge 31 of the present embodiment. Therefore, the depth D50c of the recess 50c in the comparative example is greater than the depth D50 of the recess 50 in the present embodiment (i.e., D50c>D50). In the comparative example, the undulations are relatively large and the serrations 30c do not protrude, so air tends to penetrate deeply into the recess 50c. In contrast, in the present embodiment, the undulations are relatively small and the serrations 30 protrude, so air is less likely to penetrate deeply into the recess 50 compared to the comparative example.

[0032] FIG. 6(A) shows how air that has penetrated deep into the recess 50c rises along the ridge 31c and becomes a relatively large air vortex. FIG. 6(B) shows how air turbulence occurs inside the recess 50c because the serration 30c does not protrude. FIG. 6(C) shows how air rises along the wall surface of the recess 50c, which has large undulations, and becomes a relatively large air vortex. In the comparative example, this behavior tends to make the air flow unstable, and if this causes air separation at or near the serration 30c, this can cause an increase in pressure resistance.

[0033] FIG. 7(A) shows a state in which air contacts the top of the ridge 31 and is slightly lifted before diving into the recess 50, forming a relatively small air vortex. FIG. 7(B) shows a state in which the serration 30 (ridge 31 thereof) protruding from the profile surface PF functions as a guide, and air rectification occurs inside the recess 50. FIG. 7(C) shows a state in which air is lifted along the wall surface of the recess 50 with small undulations, forming a relatively small air vortex. In the present embodiment, due to such behavior, the air flow is likely to be stabilized, and by peeling off the air further rearward, the pressure resistance can be suppressed more than in the comparative example.

[0034] From the viewpoint of reducing undulations and suppressing air resistance during running, the depth D50 of the recess 50 is preferably 0.4 mm or less. Also, from the viewpoint of appropriately increasing the height H31 of the ridge 31 to ensure the decorative effect by the serration 30, the depth D50 is preferably 0.2 mm or more. The height H31 of the ridge 31 is set, for example, to 0.3 to 0.5 mm. From the viewpoint of appropriately exerting the above-described effects, the protrusion height Ph is preferably 0.03 mm or more, and more preferably 0.06 mm or more. The protrusion height Ph is set, for example, to 10% or more and less than 50% of the height H31 of the ridge 31.

[0035] The shape of the ridge 31 as viewed along the extending direction is preferably a shape in which the width gradually increases toward the inner side in the tire axis direction, and particularly preferably a triangular shape. With such a configuration, the shadow can be made prominent (darkened) to ensure a good decorative effect. This triangular shape also includes a triangular shape with a rounded top (see FIG. 4), and the radius of curvature R31 of the top is, for example, 0.3 mm or less. The opening angle θs is, for example, 90 ± 45 degrees. In the present embodiment, the adjacent ridges 31 are arranged to be in contact with each other, but the present invention is not limited thereto, and they may be arranged with a gap therebetween.

[0036] As shown in FIG. 3, in the present embodiment, the ridge 31 extends in a direction intersecting the tire circumferential direction. According to such a configuration, since a shadow is likely to be generated, it is convenient for ensuring the decorative effect by the serration 30.

[0037] The tire T of this embodiment is configured as a so-called rotation direction specified type tire in which the rotation direction is specified. The specification of the rotation direction is performed by a display attached to the outer surface of the sidewall portion 2. The arrow RD1 in the drawing indicates the front side in the rotation direction, and the arrow RD2 indicates the rear side in the rotation direction. Note that the tire T is not limited to the rotation direction specified type tire.

[0038] As shown in FIG. 3, in the outer peripheral side region Ro, the concave portion 50 has a contour curved in a direction convex toward the front side RD1 in the rotation direction. According to such a configuration, a small air vortex can be generated in the outer peripheral side region Ro where the contribution to air resistance is large, and the separation of air can be suppressed. In the outer peripheral side region Ro, the concave portion 50 extends in a direction inclined radially outward of the tire in the direction toward the rear side RD2 in the rotation direction, and is tapered toward the rear side RD2 in the rotation direction. In the outer peripheral side region Ro, a plurality (three in this embodiment) of the concave portions 50 having such a shape are arranged at intervals in the tire circumferential direction.

[0039] As shown in FIG. 4, the wall surface 51 of the concave portion 50 is inclined in a direction to expand the opening of the concave portion 50. The angle θ51 of the wall surface 51 with respect to the normal line of the profile surface PF is preferably 15 degrees or more. Thereby, air can easily escape smoothly from the concave portion 50, and the generation of a reverse flow vortex starting from the wall surface 51 can be suppressed, which is advantageous for suppressing air resistance during traveling. From the viewpoint of clarifying the contour of the concave portion 50 and ensuring the visibility of the design, the angle θ51 is preferably 45 degrees or less.

[0040] As shown in FIG. 3, in the present embodiment, in the outer peripheral region Ro, the ridge 31 extends in a direction inclined with respect to the tire radial direction. Further, the ridge 31 extends in a direction inclined inward in the tire radial direction toward the rear side RD2 in the rotational direction, and is inclined in the opposite direction to the concave portion 50. That is, the ridge 31 extends in a direction inclined in the opposite direction to the concave portion 50 with respect to the tire radial direction. According to such a configuration, since the appearance of the shadow changes due to different reflections of light depending on the viewing direction, the visibility of the design formed by the concave portion 50 can be improved.

[0041] In the present embodiment, a pattern composed of a plurality of concave portions 50 as shown in FIG. 3 is formed at a plurality of locations (specifically, four locations) in the tire circumferential direction as shown in FIG. 2. Therefore, while ensuring the decorative effect by the serration 30, the effect of suppressing the air resistance during running and improving the low fuel consumption can be obtained more favorably. In the present embodiment, the serration 30 is provided in a belt-like region BR extending along the tire circumferential direction. The belt-like region BR is set between the circumferential protrusion 41 and the circumferential protrusion 42.

[0042] While referring to FIGS. 8 and 9, another configuration regarding the outer surface of the sidewall portion 2 will be described. FIG. 8 shows a part of the outer surface of the sidewall portion 2 and is substantially the same drawing as FIG. 2. As shown in FIG. 8, on the outer surface of the sidewall portion 2, a logo portion 10 and a decoration portion 20 arranged side by side in the tire circumferential direction with the logo portion 10 are provided. The logo portion 10 is composed of a logo such as letters, numbers, symbols, or figures, and displays information such as tire size, manufacturer name, and variety. The decoration portion 20 is composed of a decorative figure, pattern, etc., and does not include the information as described above. The decoration portion 20 is formed by the concave portion 50, and the serration 30 is disposed inside the concave portion 50.

[0043] The emblem part 10 and the decoration part 20 are each provided in the strip-shaped region BR. The emblem part 10 and the decoration part 20 are each provided at a plurality of positions (four positions in this embodiment) in the tire circumferential direction, and they are alternately arranged along the tire circumferential direction. The sum of the opening angles θ10 of each of the emblem parts 10 provided at a plurality of positions and the sum of the opening angles θ20 of each of the decoration parts 20 provided at a plurality of positions are, for example, 120 degrees or more.

[0044] FIG. 9(A) is a cross-sectional view taken along the line A-A of FIG. 8, showing the cross-section of the emblem that constitutes the emblem part 10. As shown in FIG. 9(A), the emblem part 10 is formed by a concave portion 50 that is recessed inward in the tire axial direction from the profile surface PF. Each of the other emblem parts 10 has the same cross-section as this. FIG. 9(B) is a cross-sectional view taken along the line B-B of FIG. 8 (see also FIG. 4), showing the cross-section of the pattern that constitutes the decoration part 20. As shown in FIG. 9(B), the decoration part 20 is formed by a concave portion 50 that is recessed inward in the tire axial direction from the profile surface PF. Each of the other decoration parts 20 has the same cross-section as this.

[0045] Therefore, in the outer peripheral side region Ro that is radially outside the tire diameter from the tire maximum width position Pm, all the emblem parts 10 and all the decoration parts 20 are formed by the concave portion 50 that is recessed inward in the tire axial direction from the profile surface PF. In other words, all the portions of the emblem part 10 and the decoration part 20 arranged in the outer peripheral side region Ro are formed by the concave portion 50. According to such a configuration, in the outer peripheral side region Ro where the contribution to the air resistance during running is large, all the undulations caused by the emblem part 10 and the decoration part 20 become concave shapes, so that the air resistance during running can be suppressed and the improvement of low fuel consumption can be achieved.

[0046] The belt-like region BR is provided as an annular region having a constant width and extending over the entire circumference in the tire circumferential direction. The belt-like region BR is formed in a constant region in the tire radial direction including the tire maximum width position Pm. The emblem portion 10 and the decoration portion 20 are arranged straddling the tire maximum width position Pm in the tire radial direction. In the present embodiment, all the emblem portions 10 and all the decoration portions 20 provided in the belt-like region BR are formed by the recessed portions 50. In other words, all portions of the emblem portion 10 and the decoration portion 20 provided in the belt-like region BR are formed by the recessed portions 50.

[0047] FIG. 9(C) is a cross-sectional view taken along the C-C arrow in FIG. 8, showing a cross-section of a portion surrounding the emblem portion 10 and the decoration portion 20. As shown in FIG. 9(C), the periphery of the emblem portion 10 and the decoration portion 20 is formed by the smooth surface 60. The smooth surface 60 is a smooth surface without irregularities such as protrusions, and no decoration by ridges or the like is applied. Although not shown in the drawing, the smooth surface 60 is curved along the profile surface PF. In the present embodiment, the smooth surface 60 substantially coincides with the profile surface PF.

[0048] Outside the tire radial direction from the tire maximum width position Pm, the periphery of all the emblem portions 10 and all the decoration portions 20 is formed by the smooth surface 60. In other words, in all portions of the emblem portion 10 and the decoration portion 20 arranged outside the tire radial direction from the tire maximum width position Pm, the periphery thereof is formed by the smooth surface 60. According to such a configuration, in a region that makes a large contribution to the air resistance during running, the undulations around the emblem portion 10 and the decoration portion 20 are reduced, so that the air resistance during running can be suppressed and the improvement of low fuel consumption can be achieved. In the present embodiment, in the belt-like region BR, all portions except the emblem portion 10 and the decoration portion 20 are formed by the smooth surface 60.

[0049] Reducing the undulations of the outer surface by the smooth surface 60 is effective in suppressing air resistance during driving. However, when the surface roughness of the smooth surface 60 is excessively small, the viscous resistance increases due to the adhesion of the air flowing along the outer surface of the sidewall portion 2, and the air flow velocity tends to decrease. As a result, the velocity difference between the air layer close to the outer surface of the sidewall portion 2 and the air layer far from it becomes large, air separation occurs early, and there is a risk of an increase in pressure resistance. From this perspective, it is desirable to moderately increase the surface roughness of the smooth surface 60. For example, the arithmetic mean roughness Ra of the smooth surface 60 is preferably 1.0 μm or more.

[0050] Also, in order not to generate reverse flow vortices of air due to minute irregularities on the smooth surface 60, it is desirable to moderately reduce the surface roughness of the smooth surface 60. For example, the arithmetic mean roughness Ra of the smooth surface 60 is preferably 2.4 μm or less. Therefore, the arithmetic mean roughness Ra of the smooth surface 60 is set to, for example, 1.7 ± 0.7 μm. The arithmetic mean roughness Ra is defined in JIS B0601:2013, and the evaluation method and procedure conform to the provisions of JIS B0633:2001.

[0051] In the outer peripheral side region Ro, a circumferential protrusion 41 extending annularly along the tire circumferential direction is provided. The belt region BR is provided radially inward of the tire diameter of the circumferential protrusion 41. The circumferential protrusion 41 is disposed radially inward of the tire diameter of the mold split position Ps. In the inner peripheral side region Ri, circumferential protrusions 42 and 43 extending annularly along the tire circumferential direction are provided. The belt region BR is provided radially outward of the tire diameter of the circumferential protrusion 42. The belt region BR is provided between a pair of circumferential protrusions 41 and 42 protruding outward in the tire axial direction.

[0052] In the inner peripheral side region Ri, since the contribution to air resistance during driving is small, a logo portion or a decorative portion protruding outward in the tire axial direction from the profile surface PF may be provided. In the present embodiment, a logo portion 70 for displaying information such as the manufacturing year week is provided radially inward of the circumferential protrusion 42, and this logo portion 70 protrudes outward in the tire axial direction from the profile surface PF.

[0053] The selection 30 as described above may be provided on the outer surface of at least one of the pair of side wall portions 2.

[0054] Unless otherwise specified, the dimensions, angles, positional relationships, etc. of each part of the tire shall be determined in a no-load state where the tire mounted on the regular rim is filled with the regular internal pressure. The regular rim is the rim determined for each tire in the standard system including the standard on which the tire is based. For example, it is the standard rim in JATMA, and it is the "Measuring Rim" in TRA and ETRTO.

[0055] The regular internal pressure is the air pressure determined for each tire in the standard system including the standard on which the tire is based. In the case of truck and bus tires and light truck tires, in JATMA, it is the maximum air pressure; in TRA, it is the value corresponding to the Load Index described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; in ETRTO, it is the "INFLATION PRESSURE". In the case of passenger car tires, it is usually 250 kPa, but in the case of tires marked as Extra Load or Reinforced, it is 290 kPa.

[0056] It is understood by those skilled in the art that the above-described embodiments are specific examples of the following aspects.

[0057] [1] The pneumatic tire of the present disclosure includes a pair of sidewall portions, and a serration in which ridges are arranged is formed in an outer peripheral side region that is radially outside the tire at the maximum tire width position on the outer surface of at least one of the pair of sidewall portions. The serration is disposed in a recess that is recessed inward in the tire axial direction from the profile surface of the sidewall portion, and protrudes with a protrusion height of 0.1 mm or less from the profile surface. According to such a configuration, while ensuring the decorative effect by the serration, it is possible to suppress the air resistance during running and improve the low fuel consumption.

[0058] [2] In the pneumatic tire of the above [1], it is preferable that the depth of the recess with respect to the profile surface is 0.4 mm or less. By reducing the undulation caused by the recess, the effect of suppressing the air resistance during running is enhanced.

[0059] [3] In the pneumatic tire of the above [1] or [2], the rotation direction is specified, and in the outer peripheral side region, the recess may have a curved contour that is convex toward the front side in the rotation direction. According to such a configuration, small air vortices are generated in the outer peripheral side region where the contribution to air resistance is large, and air separation can be suppressed, which is convenient for suppressing the air resistance during running.

[0060] [4] In the pneumatic tire according to any one of the above [1] to [3], the recess extends in a direction inclined with respect to the tire radial direction, and the ridge may extend in a direction inclined in the opposite direction to the recess with respect to the tire radial direction. According to such a configuration, since the way of seeing the shadow changes due to the different reflection of light depending on the viewing direction, the visibility of the design formed by the recess can be improved.

[0061] The pneumatic tire T of the present disclosure can be configured in the same manner as a normal pneumatic tire except that the sidewall portion 2 is configured as described above, and any of the conventionally known shapes and materials can be adopted.

[0062] Although the embodiments of the present disclosure have been described with reference to the drawings, the specific configuration should not be considered to be limited to these embodiments. The scope of the present disclosure is shown not only by the description of the above embodiments but also by the scope of the claims, and further includes all modifications within the meaning and scope equivalent to the scope of the claims.

[0063] The pneumatic tire of the present disclosure is not limited to the above-described embodiments at all, nor is it limited to the above-described effects. The tire of the present disclosure can be variously improved and modified without departing from the gist thereof. Further, each configuration adopted in the above-described embodiments can be arbitrarily combined and adopted.

Description of Reference Numerals

[0064] 2 Sidewall portion 30 Siping 31 Ridge 50 Recess 51 Wall surface

Claims

**Claim 1** A pneumatic tire having a pair of sidewall portions, wherein a serration having ridges arranged therein is formed in an outer peripheral side region on the outer diameter side in the tire radial direction with respect to the tire maximum width position on the outer surface of at least one of the pair of sidewall portions, the serration is disposed in a recess recessed inward in the tire axial direction with respect to the profile surface of the sidewall portion and protrudes with a protrusion height of 0.1 mm or less from the profile surface. **Claim 2** The pneumatic tire according to claim 1, wherein the depth of the recess with respect to the profile surface is 0.4 mm or less. **Claim 3** The rotational direction is specified, in the outer peripheral side region, the recess has a curved contour that is convex toward the front side in the rotational direction, the pneumatic tire according to claim 1. **Claim 4** the recess extends in a direction inclined with respect to the tire radial direction, the ridge extends in a direction inclined in the opposite direction to the recess with respect to the tire radial direction, the pneumatic tire according to any one of claims 1 to 3.

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