pneumatic tires

Abstract

Pneumatic tires (1), comprising: a plurality of survey sections (9) extending along a tire sidewall (Sa) of a tire sidewall section (S) in a direction that intersects a tire circumferential direction and a tire radial direction; the majority of survey sections (9), each of which includes the following: a section (9A) in the middle of a direction of travel, which includes a highest point (hH) of a projection height (h) from the tire sidewall (Sa), and in the direction of travel peak sections (9B) on each side of the middle section (9A), which include a lowest point (hL) of a projection height (h) from the tire sidewall (Sa), wherein at least the central section (9A) is arranged in the tire radial direction only outwards from a widest point (H) of the tire; and where a ratio of a total width SW to an outer diameter OD satisfies the relationship SW / OD ≤ 0.3, where a ratio of an inner diameter RD to the outer diameter OD satisfies the relationship RD / OD ≥ 0.7, and where a change in the mass of the survey section (9) in the tire circumferential direction per 1 degree in the tire circumferential direction is 0.1 g / degree or less.

Description

[0001] The present invention relates to a pneumatic tire. State of the art

[0002] JP 2013-018474 A describes a vehicle tire having a sidewall formed with curved ridge portions. JP 2013-018474 A describes how the airflow against the sidewall does not flow naturally along the sidewall. Instead, the air moves within a wheel house, creating a downforce that pushes the upper part of a tread portion downward. Note that the downforce generated reduces lift, a force that lifts the vehicle upward.

[0003] Furthermore, WO 2014 / 024587 A1 describes a circumferential ridge portion extending longitudinally along mainly a tire circumferential direction, wherein the ridge portion is arranged outward from the widest point of the tire in the tire radial direction on at least one tire side portion. In WO 2014 / 024587 A1, since the air flowing through the tire side portion is swirled by the circumferential ridge portion, a boundary layer of turbulent flow is generated around the pneumatic tire. This suppresses the expansion of the air flowing outward from the rear of the vehicle on the vehicle outer side. As a result, the spreading of the flowing air can be suppressed, the air resistance of the pneumatic tire can be reduced, and fuel economy can be improved.

[0004] It should be noted that WO 2011 / 135774 A1 describes technology in which the air resistance around the tire can be reduced by lowering the overall width of the pneumatic tire and thus lowering the front protruding surface (i.e. the protruding surface when viewed from the direction of travel of the pneumatic tire).

[0005] US 2015 / 0 114 538 A1 discloses a pneumatic tire with land portions extending radially along the tire side surface. The land portions include center portions and tip portions. US 2015 / 0 114 538 A1 also shows land portions, wherein at least the center portion is located only outwardly of a widest point of the tire in the tire radial direction.

[0006] US 2011 / 0 088 826 A1 discloses a pneumatic tire with land portions that optionally extend along the tire side surface in a direction intersecting a tire circumferential direction and a tire radial direction. The land portions include center portions and tip portions and extend along the entire tire side surface of the tire.

[0007] DE 11 2016 001 636 T5 discloses a pneumatic tire capable of providing reduced lift and drag while maintaining good uniformity. The pneumatic tire includes a plurality of land portions extending along a tire side surface of a tire side portion in a direction intersecting a tire circumferential direction and a tire radial direction. Summary of the inventionTechnical problem

[0008] However, the pneumatic tires described in JP 2013-018474 A and WO 2014 / 024587 A1 may experience a decrease in uniformity in the tire circumferential direction due to the land portions, ridges, or land portions arranged in the circumferential direction, resulting in a loss of good uniformity.

[0009] In view of the above, an object of the present invention is to provide a pneumatic tire capable of providing reduced lift and drag while maintaining good uniformity. Solution to the problem

[0010] In order to solve the problems described above and to achieve the objects described above, a pneumatic tire according to the present invention comprises a plurality of land portions extending along a tire side surface of a tire side portion in a direction intersecting a tire circumferential direction and a tire radial direction; wherein the plurality of land portions each include a central portion in an extending direction including a highest point of a protrusion height from the tire side surface, and tip portions on both sides of the central portion in the extending direction including a lowest point of the protrusion height from the tire side surface; wherein at least the central portion is located only outward in the tire radial direction from a widest point of the tire; and a ratio of a total width SW to an outer diameter OD satisfies the relationship SW / OD ≤ 0.3.

[0011] At this time, a ratio of an inner diameter RD to the outer diameter OD satisfies the relationship RD / OD ≥ 0.7, and a change in the mass of the land portion in the tire circumferential direction per 1 degree in the tire circumferential direction is 0.1 g / degree or less.

[0012] According to the pneumatic tire, the lobe portions that rotate when the vehicle is traveling cause the air to swirl and minimize the slow airflow around the pneumatic tire. More specifically, in the lower portion of the pneumatic tire, when the pneumatic tire rotates, the speed of the air flowing along the lower portion of the vehicle is increased. This reduces the airflow from the bottom to the top, suppressing the upward air pressure. As a result, lift can be suppressed, the contact of the pneumatic tire with the ground can be improved, and steering stability, which is a measure of the vehicle's driving performance, can be improved. In addition, when the pneumatic tire rotates, a boundary layer of turbulent flow is generated in the upper portion of the pneumatic tire. This promotes the airflow around the pneumatic tire.As a result, the expansion of the air flow is suppressed, which reduces the tire's aerodynamic drag. This reduction in aerodynamic drag leads to an improvement in the vehicle's fuel consumption.

[0013] Furthermore, according to the pneumatic tire, the central portion in the extending direction intersecting the tire circumferential direction and the tire radial direction in the land portion includes the highest point of the protrusion height from the tire side surface, and the tip portions provided on both sides of the central portion in the extending direction each include the lowest point of the protrusion height from the tire side surface. Accordingly, the mass of the land portion is lower at the tip portions. As a result, a sudden change in the mass from the tire side surface is prevented in the area near the tip portions of the land portion, thereby improving uniformity in the tire circumferential direction, and thereby improving uniformity.

[0014] Furthermore, according to the pneumatic tire, the center portion of the land portion, which includes the highest point of the protrusion height, is located just outward from the widest point of the tire in the tire radial direction. Thus, the air resistance is reduced near the widest point of the tire, where the pneumatic tire is widest in the tire transverse direction, making the air resistance there also high. As a result, the air resistance is further reduced.

[0015] Furthermore, according to the pneumatic tire of the present invention, since the ratio of the total width SW to the outer diameter OD satisfies the relationship SW / OD ≤ 0.3, the total width is smaller and the outer diameter is larger than that of a typical pneumatic tire. Thus, the rolling resistance and air resistance during running can be reduced. While large-diameter tires, in particular, tend to have increased air resistance caused by the failure to generate turbulent airflow due to a decrease in the relative speed between the side portion on the upper portion of the tire and the air, the pneumatic tire of the present embodiment has a land portion and satisfies the relationship of the ratio of the total width SW to the outer diameter OD.Thus, the air flow at the side portion can be swirled at the upper portion of the tire, thereby maintaining an effect of reducing air resistance.

[0016] Thus, the pneumatic tire can provide reduced lift and drag while maintaining good uniformity.

[0017] In the pneumatic tire according to another embodiment of the present invention, the center portion and the tip portions of the land portion are arranged outward in the tire radial direction from the widest part of the tire.

[0018] According to the pneumatic tire, by arranging the tip portions not beyond the widest point of the tire, the air resistance is reduced at the widest point of the tire, where the pneumatic tire is widest in the tire transverse direction, and where the air resistance is also high. As a result, the effect of significantly reducing air resistance can be achieved.

[0019] In the pneumatic tire according to the present invention, a change in the mass of the land portion in the tire circumferential direction per 1 degree in the tire circumferential direction is 0.1 g / degree or less.

[0020] According to the pneumatic tire, by specifying the change in the mass of the land portion in the tire circumferential direction, the uniformity in the tire circumferential direction is improved. As a result, the effect of significantly improving the uniformity can be achieved. In the pneumatic tire according to another embodiment of the present invention, the central portion of the

[0021] The elevation section has a projection height in the range of 1 mm to 10 mm.

[0022] If the protrusion height of the center section is less than 1 mm, the effect of accelerating the airflow flowing along the lower section of the vehicle and generating a boundary layer of turbulent flow is difficult to achieve. If the protrusion height of the center section is greater than 10 mm, the amount of airflow colliding with the lobe section will increase. As a result, drag is likely to increase. Therefore, to achieve the effect of significantly reducing lift and drag, the protrusion height of the center section is preferably in the range of 1 mm to 10 mm.

[0023] In the pneumatic tire according to another embodiment of the present invention, the land portion protrudes 5 mm or less in a tire transverse direction from a tire section width at the widest part of the tire when the pneumatic tire is mounted on a normal rim, inflated to a normal internal pressure, in an unloaded state, and viewed in a meridian cross section.

[0024] If the land portion protrudes more than 5 mm outward in the tire transverse direction from the tire cross-sectional width at the widest point, the amount of airflow colliding with the land portion is increased. As a result, the air resistance of the land portion is likely to increase. Thus, by specifying the range in which the land portion protrudes outward in the tire transverse direction from the tire cross-sectional width at the widest point, an increase in air resistance caused by the land portion can be suppressed, and the effect of the land portion significantly improving low-speed airflow can be achieved.

[0025] In the pneumatic tire according to another embodiment of the present invention, a groove is formed on a surface of the land portion.

[0026] According to the pneumatic tire, the rigidity of the land portion is reduced by forming the groove. As a result, a decrease in ride comfort due to the land portions making the tire side portion a rigid structure can be suppressed. In addition, the formation of the groove reduces the mass of the land portion. As a result, a decrease in uniformity due to the land portions increasing the mass of the tire side portion can be suppressed.

[0027] In the pneumatic tire according to another embodiment of the present invention, a depressed portion is formed on a surface of the land portion.

[0028] According to the pneumatic tire, the rigidity of the land portion is reduced by forming the depressed portion. As a result, a decrease in ride comfort due to the tire side portion being made into a rigid structure by the land portions can be suppressed. In addition, by forming the depressed portion, the mass of the land portion is reduced. As a result, a decrease in the uniformity of the tire side portion due to the land portions can be suppressed. In addition, by forming the depressed portion and the groove, the above-described effects can be further improved.

[0029] In the pneumatic tire according to another embodiment of the present invention, the plurality of land portions are arranged at uneven intervals in the tire circumferential direction.

[0030] According to the pneumatic tire, by counteracting the periodicity of the land portions in the tire circumferential direction with respect to the airflow along the tire side surface of the tire side portion, the difference in frequency disperses and equalizes the sound pressure generated by the land portions. As a result, noise can be reduced.

[0031] In the pneumatic tire according to another embodiment of the present invention, an orientation with respect to a vehicle inside / outside is prescribed when the pneumatic tire is mounted on a vehicle, and the plurality of land portions are formed at least on a tire side portion corresponding to a vehicle outside.

[0032] According to the pneumatic tire, the tire side portion on the outer side of the vehicle protrudes beyond the tire housing when the pneumatic tire is mounted on the vehicle. By providing the raised portions on the tire side portion on the outer side of the vehicle, the airflow can be forced toward the outer side of the vehicle. This can achieve the effect of significantly reducing lift and drag. Advantageous effects of the invention

[0033] The pneumatic tire according to an embodiment of the present invention can provide reduced lift and drag while maintaining good uniformity. Brief description of the drawings Fig. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment of the present invention. Fig. 2 is a meridian cross-sectional view of the entire pneumatic tire according to an embodiment of the present invention. Fig. Figure 3 is a table showing the coefficients defined by aspect ratios. Fig. 4 is a table giving the specified rim widths, which are the values ​​corresponding to the values ​​obtained by the products of the coefficients as shown in the table of Fig. 3 defined, obtained, are closest. Fig. 5 is a side view of another example of a pneumatic tire according to an embodiment of the present invention. Fig. 6 is an enlarged view of a bump portion as seen from the side of a pneumatic tire. Fig. 7 is a side view of a survey section. Fig. 8 is a side view of another example of a pneumatic tire according to an embodiment of the present invention. Fig. 9 is a side view of another example of a pneumatic tire according to an embodiment of the present invention. Fig. 10 is a side view of another example of a pneumatic tire according to an embodiment of the present invention. Fig. 11 is a side view of another example of a pneumatic tire according to an embodiment of the present invention. Fig. 12 is a cross-sectional view of a bump portion in the transverse direction. Fig. 13 is a cross-sectional view of a bump portion in the transverse direction. Fig. 14 is a cross-sectional view of a bump portion in the transverse direction. Fig. 15 is a cross-sectional view of a bump portion in the transverse direction. Fig. 16 is a cross-sectional view of a bump portion in the transverse direction. Fig. 17 is a cross-sectional view of a bump portion in the transverse direction. Fig. 18 is a cross-sectional view of a bump portion in the transverse direction. Fig. 19 is a cross-sectional view of a bump portion in the transverse direction. Fig. 20 is a cross-sectional view of a bump portion in the transverse direction. Fig. 21 is a cross-sectional view of a bump portion in the transverse direction. Fig. 22 is a cross-sectional view of a bump portion in the transverse direction. Fig. 23 is a cross-sectional view of a bump portion in the transverse direction. Fig. 24 is a diagram for explaining the function of a pneumatic tire according to an embodiment of the present invention. Fig. 25 is a diagram for explaining the function of a pneumatic tire according to an embodiment of the present invention. Fig. 26 is a meridian cross-sectional view of a portion of a pneumatic tire according to an embodiment of the present invention. Fig. 27 is an enlarged view of a land portion in which grooves are formed, viewed from the side of a pneumatic tire. Fig. 28 is a cross-sectional view taken along a line AA of Fig. 27. Fig. 29 is an enlarged view of another example of a land portion in which grooves are formed, as seen from the side of a pneumatic tire. Fig. 30 is an enlarged view of a land portion in which recessed portions are formed, as seen from the side of a pneumatic tire. Fig. 31 is a cross-sectional view taken along a line BB of Fig. 30. Fig. 32 is an enlarged view of a land portion in which grooves and depressed portions are formed, as seen from the side of a pneumatic tire. Fig. 33 is a table showing results of performance tests of pneumatic tires according to Examples of the present invention. Fig. 34 is a side view of a portion of a pneumatic tire according to an example of the prior art. Description of embodiments

[0034] Embodiments of the present invention will be explained in detail below with reference to the drawings.

[0035] Fig. 1 is a meridian cross-sectional view of a pneumatic tire according to the present embodiment. Fig. 2 is a meridian cross-sectional view of the entire pneumatic tire according to the present embodiment.

[0036] In the following description, “tyre radial direction” means the direction perpendicular to the rotation axis P of a pneumatic tire 1 (see Fig. 2). “Tire radial inward” refers to the direction toward the rotation axis P in the tire radial direction. “Tire radial outward” refers to the direction away from the rotation axis P in the tire radial direction. “Tire circumferential direction” means the circumferential direction whose central axis is the rotation axis P. Furthermore, “tire transverse direction” means the direction parallel to the rotation axis P. “Tire transverse inward” refers to the direction toward a tire equatorial plane CL (a tire equator line) in the tire transverse direction. “Tire transverse outward” refers to the direction away from the rotation axis in the tire equatorial plane CL. “Tire equatorial plane CL” means a plane perpendicular to the rotation axis P of the pneumatic tire 1 and passing through a center in the tire transverse direction of the pneumatic tire 1."Tire width" is a width in the tire transverse direction between components located outward in the tire transverse direction, or in other words, the distance between the components farthest from the tire equatorial plane CL in the tire transverse direction. "Tire equator line" refers to the line along the tire circumferential direction of the pneumatic tire 1 that lies on the tire equatorial plane CL. In the present embodiment, the tire equator line and the tire equatorial plane CL are both denoted by reference symbol CL.

[0037] As in Fig. As shown in Figure 1, the pneumatic tire 1, which is mainly used as a passenger car, includes a tread portion 2, shoulder portions 3 on opposite sides of the tread portion 2, and sidewall portions 4 and bead portions 5 arranged in this order from the respective shoulder portions 3. Furthermore, the pneumatic tire 1 includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

[0038] The tread portion 2 is formed of rubber material (tread rubber) and is exposed on the outermost side of the pneumatic tire 1 in the tire radial direction, and its surface forms the pattern of the pneumatic tire 1. A tread surface 21 is formed on an outer peripheral surface of the tread portion 2, or in other words, on a road contact surface that comes into contact with a road surface during running. The tread surface 21 is provided with a plurality (four in the present embodiment) of main grooves 22, which are straight main grooves extending in the tire circumferential direction parallel to the tire equator line CL. Further, in the tread surface 21, a plurality of rib-like land portions 23 extending along the tire circumferential direction and parallel to the tire equator line CL are formed by the plurality of main grooves 22.In addition, although not explicitly shown in the drawings, lug grooves that intersect with the main grooves 22 in each of the land portions 23 are provided in the tread surface 21. The land portions 23 are divided into a plurality of segments in the tire circumferential direction by the lug grooves. Furthermore, lug grooves are formed on the outermost side of the tread portion 2 in the tire transverse direction so as to open outward in the tire transverse direction of the tread portion 2. Note that the lug grooves may have a shape where they are connected to the main grooves 22 or a shape where they are not connected to the main grooves 22.

[0039] The shoulder portions 3 are areas of the tread portion 2 located on both sides in the tire transverse direction. Furthermore, the sidewall portions 4 are exposed at the outermost sides of the pneumatic tire 1 in the tire transverse direction. The bead portions 5 each include a bead core 51 and a bead filler 52. The bead core 51 is formed by a bead wire, which is a steel wire, wound into a ring shape. The bead filler 52 is a rubber material arranged in a space formed by folding one end of the carcass layer 6 in the tire transverse direction at the position of the bead core 51.

[0040] The end portions of the carcass layer 6 in the tire transverse direction are folded around the pair of bead cores 51 from the inside to the outside in the tire transverse direction, and the carcass layer 6 is stretched in an annular shape in the tire circumferential direction to form the skeleton of the tire. The carcass layer 6 is formed of a plurality of carcass cords with rubber coating (not shown) arranged in alignment at an angle with respect to the tire circumferential direction that coincides with the tire meridian direction. The carcass cords are made of organic fibers (e.g., polyester, rayon, nylon, or the like). At least one carcass layer 6 is provided.

[0041] The belt layer 7 has a multi-layer structure, with at least two belts 71, 72 superimposed on one another. In the tread portion 2, the belt layer 7 is arranged outside the carcass layer 6 in the tire radial direction, i.e., on the outer circumference thereof, and covers the carcass layer 6 in the tire circumferential direction. The belts 71 and 72 include a plurality of cords (not shown) arranged in alignment at a predetermined angle (e.g., from 20° to 30°) to the tire circumferential direction and covered with a coating of rubber. The cords are made of steel or organic fibers (polyester, rayon, nylon, or the like). In addition, the belts 71 and 72 overlap each other and are arranged so that the direction of the cords of the respective belts intersects.

[0042] The belt reinforcing layer 8 is arranged outside the belt layer 7 in the tire radial direction, ie, on its outer circumference, and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 includes a plurality of cords (not shown) arranged in the tire transverse direction and substantially parallel (±5°) to the tire circumferential direction, and covered with a coating rubber. The cords are made of steel or organic fibers (polyester, rayon, nylon, or the like). Fig. The belt reinforcing layer 8 shown in FIG. 1 is arranged to cover end portions of the belt layer 7 in the tire transverse direction. The configuration of the belt reinforcing layer 8 is not limited to that described above. Although not shown in the drawings, a configuration in which the belt reinforcing layer 8 is arranged to cover the entire belt layer 7 may be adopted. Alternatively, for example, a two-reinforcing layer configuration may be adopted in which the reinforcing layer inner in the tire radial direction is formed larger in the tire transverse direction than the belt layer 7 so as to cover the entire belt layer 7, and the reinforcing layer outer in the tire radial direction is arranged to cover only the end portions of the belt layer 7 in the tire transverse direction.In another example, a two-reinforcement layer configuration may be used, in which each of the reinforcing layers is arranged to cover only the end portions of the belt layer 7 in the tire transverse direction. In other words, the belt reinforcing layer 8 overlaps at least the end portions of the belt layer 7 in the tire transverse direction. Furthermore, the belt reinforcing layer 8 is made of a band-shaped strip material (e.g., with a width of 10 mm) wound in the tire circumferential direction.

[0043] Fig. Figure 3 is a table showing the coefficients defined by the aspect ratios. Fig. 4 is a table giving the specified rim widths, which are the values ​​corresponding to the values ​​obtained by the products of the coefficients as shown in the table of Fig. 3 defined, obtained, are closest. Fig. 5 is a side view of a pneumatic tire according to an embodiment of the present invention. Fig. 6 is an enlarged view of a bump portion as seen from the side of the pneumatic tire. Fig. 7 is a side view of a survey section. Fig. 8 to 11 are side views of other examples of a pneumatic tire according to the present embodiment. Fig. 12 to 23 are cross-sectional views of a raised section in the transverse direction. Fig. 24 and Fig. 25 are explanatory diagrams of the function of a pneumatic tire according to the present embodiment. Fig. 26 is a meridian cross-sectional view of a portion of the pneumatic tire according to the present embodiment. Fig. 27 is an enlarged view of a land portion in which grooves are formed, viewed from the side of a pneumatic tire. Fig. 28 is a cross-sectional view taken along a line AA of Fig. 27. Fig. 29 is an enlarged view of another example of a land portion in which grooves are formed, as seen from the side of a pneumatic tire. Fig. 30 is an enlarged view of a land portion in which recessed portions are formed, as seen from the side of a pneumatic tire. Fig. 31 is a cross-sectional view taken along a line BB of Fig. 30. Fig. 32 is an enlarged view of a land portion in which grooves and depressed portions are formed, as seen from the side of a pneumatic tire.

[0044] Herein, the total width SW is the interval between the sidewall portions 4, including any designs (patterns or alphanumeric characters on the tire side surface) on the sidewall portions 4 when the pneumatic tire 1 is mounted on a regular rim, inflated to a regular internal pressure (for example, 230 kPa), and in an unloaded state. The outer diameter OD is the outer diameter of the tire under the same conditions, and an inner diameter RD is the inner diameter of the tire under the same conditions. Note that the internal pressure of 230 kPa described above is selected to indicate the dimensions of the pneumatic tire, such as the total width SW. All tire dimensional parameters specified in this specification are determined based on an internal pressure of 230 kPa and in an unloaded state.However, it should be clarified that inflation to an internal pressure of 230 kPa is not necessary for the application of the present invention, and the pneumatic tire 1 according to the present invention exhibits the effects of the present invention when inflated to an internal pressure within the normally used range.

[0045] In addition, as in Fig. 1, "tire side portion S" refers to the surface that extends smoothly from a ground contact edge T of the tread portion 2 outward in the tire radial direction, or in other words, a range from a rim inspection line R outward in the tire radial direction. Furthermore, "ground contact edge T" refers to both outermost edges in the tire transverse direction of a range where the tread surface 21 of the tread portion 2 of the pneumatic tire 1 comes into contact with the road surface when the pneumatic tire 1 is mounted on a normal rim, inflated to the normal internal pressure, and loaded with 70% of the regular load. The ground contact edge T is formed continuously in the tire circumferential direction.Furthermore, “rim inspection line R” refers to a line used to confirm whether the tire has been correctly mounted on the rim, and is generally an annular convex line that is closer to the outer side in the tire radial direction than a rim flange and continues in the tire circumferential direction along a portion near the rim flange on a front surface of the tire bead portions 5.

[0046] As in Fig. 1, "tire widest point H" refers to the ends of the tire section width HW where the width in the tire transverse direction is the largest. The "tire section width HW" is the maximum overall tire width SW in the tire transverse direction, excluding any patterns or alphanumeric characters on a tire side surface, when the pneumatic tire 1 is mounted on a normal rim, inflated to normal internal pressure, and in an unloaded state. For tires provided with a rim protector (provided in the tire circumferential direction and projecting outward in the tire radial direction) for rim protection, the rim protector represents the outermost portion in the tire transverse direction, but the tire section width HW in the present embodiment does not include the rim protector.

[0047] Here, "normal rim" refers to a "standard rim" as defined by the Japan Automobile Tire Manufacturers Association (JATMA), a "design rim" as defined by the Tire and Rim Association (TRA), or a "measuring rim" as defined by the European Tire and Rim Technical Organization (ETRTO). "Normal internal pressure" refers to a "maximum air pressure" as defined by JATMA, a maximum value in "tire load limits at various cold inflation pressures" as defined by TRA, or "inflation pressures" as defined by ETRTO. “Regular load” refers to “Maximum Load Capacity” as defined by JATMA, a maximum value in “TIRE ROAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” as defined by TRA and “LOAD CAPACITY” as defined by ETRTO.

[0048] In a pneumatic tire 1 of the present embodiment, as shown in Fig. As shown in Figure 2, according to the present invention, the ratio of the total width SW to the outer diameter OD satisfies the relationship SW / OD ≤ 0.3. In the pneumatic tire 1 of the present embodiment, the ratio of the inner diameter RD to the outer diameter OD satisfies the relationship RD / OD ≥ 0.7.

[0049] The rim used in the present embodiment has a rim diameter compatible with the inner diameter of the pneumatic tire 1 and has a nominal rim width corresponding to the Fig. 4, which is the value closest to the value (Rm = K1 × Sn) obtained by the product of the nominal tyre section width Sn and the coefficient K1 obtained according to the aspect ratio of the tyre mounted on the rim in accordance with ISO 4000-1:2001 in the correspondence table of Fig. 3 is described.

[0050] In the pneumatic tire 1 of the present embodiment, as shown in Fig. 5 to 7, at least one side portion S is provided with a ridge portion 9 that protrudes outward beyond a side surface Sa corresponding to the profile of the surface of the tire side portion S. The ridge portion 9 is formed of a rubber material (the same rubber material as that constituting the tire side portion S or a different rubber material) as a ridge that extends along the tire side surface Sa of the tire side portion S in a direction intersecting the tire circumferential direction and the tire radial direction. In the present embodiment, the ridge portion 9 shown in the drawings curves into a C-shape when viewed from the side of the pneumatic tire 1.The bump portion 9 is not limited to being curved, and may be linear when viewed from the side of the pneumatic tire 1, may be formed in a V-shape, may be formed in an S-shape, may have a meander configuration, or may have a zigzag shape.

[0051] As in Fig. 6 and Fig. As shown in Fig. 7, the land portion 9 includes a central portion 9A in the extending direction and tip portions 9B provided to extend from the central portion 9A on each side in the extending direction. The central portion 9A is the portion within 25% of the length L of the land portion 9 in the extending direction from a center 9C on each side in the extending direction. The tip portions 9B are portions extending from the central portion 9A on both sides in the extending direction, excluding 5% of the length L of the land portion 9 in the extending direction from ends 9D in the extending direction. The length L of the land portion 9 in the extending direction is the shortest distance between the ends 9D of the land portion 9.

[0052] The middle portion 9A also includes a highest point hH at which the projection height h from the tire side surface Sa is the greatest. The tip portion 9B also includes a lowest point hL at which the projection height h from the tire side surface Sa is the smallest. Fig. 7, the projection height h of the raised portion 9 gradually increases in the direction from one end 9D to the center 9C and gradually decreases from the center 9C to the other end 9D. In such a configuration, the highest point hH of the projection height h corresponds to the center 9C, and the lowest point hL corresponds to the ends of the tip portions 9B, ie, the points corresponding to 5% of the length L from the ends 9D. Note that the Fig. 7, the protrusion height h of the raised portion 9 is shown with an arcuate change in the direction of extension. However, this is not intended as a limitation, and the change may also be linear. Furthermore, the highest point hH may encompass the entire central portion 9A, and with such a configuration, the tip portions 9B may have a protrusion height h that gradually decreases from the central portion 9A.

[0053] As in Fig. 5, the land portion 9 is arranged in the region of the tire side portion S in the tire radial direction outward from a widest point of the tire H. A plurality of land portions 9 are arranged at predetermined intervals in the tire circumferential direction.

[0054] As in Fig. 8, the raised portion 9 may extend inward in the tire radial direction partially beyond the widest point of the tire H. In such a configuration, the central portion 9A is arranged outward in the tire radial direction from the widest point of the tire H, and at least one of the tip portions 9B (or the area of ​​5% of the length L from the end 9D) extends inward in the tire radial direction beyond the widest point of the tire H. In Fig. 8, all the raised portions 9 extend partially inward in the tire radial direction beyond the widest point of the tire H, but in another embodiment, this may apply only to a portion of the raised portions 9. Therefore, the raised portions 9 are arranged in the region of the tire side portion S such that the main portion (the central portion 9A) is positioned outward in the tire radial direction from a widest point of the tire H.

[0055] As in Fig. 5, Fig. 9, Fig. 10 and Fig. 11, the number of the protrusion portions 9 arranged in the tire circumferential direction is not limited to a specific number. As shown in Fig. 10 and Fig. 11, the elevation portions 9 may also vary in inclination in the direction of extension with respect to the tire circumferential direction and the tire radial direction.

[0056] The Fig. 12 has a four-sided cross-sectional shape in the transverse direction, which is perpendicular to the direction of the elevation section 9. The Fig. The elevation section 9 shown in Figure 13 has a triangular cross-sectional shape in the transverse direction. Fig. The elevation section 9 shown in Figure 14 has a trapezoidal cross-sectional shape in the transverse direction.

[0057] Likewise, the cross-sectional shape of the raised sections 9 in the transverse direction may have an external shape based on curved lines. Fig. The raised portion 9 shown in Figure 15 has a semicircular cross-sectional shape in the transverse direction. Although not shown in the drawings, the cross-sectional shape of the raised portion 9 in the transverse direction may also have a semi-oval shape, a semi-elliptical shape, or any other arc shape.

[0058] Furthermore, the cross-sectional shape of the raised portion 9 in the transverse direction may have an external shape based on a combination of straight and curved lines. Fig. The elevation portion 9 shown in Figure 16 has a cross-sectional shape in the transverse direction which is a quadrilateral shape with rounded corners. Fig. The elevation portion 9 shown in Figure 17 has a cross-sectional shape in the transverse direction which is a triangular shape with rounded corners. Furthermore, as shown in Figures Fig. 16 to 18, the cross-sectional shape in the lateral direction of the tire ridges 9 may have a shape in which the base portion protruding from the tire side portion S is curved.

[0059] In addition, the cross-sectional shape of the raised portion 9 in the transverse direction may be a combination of different shapes. Fig. 19 includes a quadrilateral upper section formed by a plurality of triangular shapes (two in Fig. 19) is given a zigzag shape. Fig. The elevation section 9 shown in Figure 20 includes a four-sided upper section tapered by a single triangular shape. Fig. The elevation section 9 shown in Figure 21 includes a four-sided upper section which is formed as a four-sided depression. Fig. The elevation section 9 shown in Figure 22 includes a four-sided upper section formed as a four-sided depression, wherein the projection height is different on each side of the depression. Fig. 23 includes a four-sided platform portion 9a formed to protrude from the tire side portion S. On the platform portion 9a, a plurality of four-sided shapes (two in Fig. 23) protrudes. Although not shown in the drawings, the cross-sectional shape of the raised portion 9 in the transverse direction may further include a quadrilateral upper portion having a wave-like shape or have another shape.

[0060] Furthermore, in the present embodiment, the cross-sectional area of ​​the cross-sectional shape in the transverse direction of the land portion 9, such as the one described above, is largest at the highest point hH of the protrusion height h of the middle portion 9A, and the cross-sectional area is small at the lowest points hL of the protrusion height h of the tip portions 9B. A width W in the transverse direction may follow the change in the protrusion height h and be largest at the highest point hH and smallest at the lowest point hL, or sometimes may not change at all in this way.

[0061] The function of the pneumatic tire 1 is in Fig. 24. When the pneumatic tire 1 is mounted on a rim 50 and then on a vehicle 100, the pneumatic tire 1 is arranged in a tire housing 101 of the vehicle 100. When the pneumatic tire 1 rotates in this position in the direction Y1, the vehicle 100 travels in the direction Y2. When the vehicle 100 is traveling, the air flow in the vicinity of the pneumatic tire 1 has a low speed. In response to the slow air flow, an air flow is generated from the bottom to the top in the wheel housing 101. This, in turn, generates lift, i.e., a force that lifts the vehicle 100 upward. In addition, in response to the slow air flow, an air cushion that separates from the vehicle 100 is formed outside the tire housing 101, thereby causing air resistance.

[0062] In view of this phenomenon, the pneumatic tire 1 of the present embodiment includes land portions 9 that rotate in the rotational direction Y1 when the vehicle 100 travels. The land portions 9 cause the air around the tire 1 to swirl and minimize the above-described slow airflow. More specifically, in the lower portion of the pneumatic tire 1, when the pneumatic tire 1 rotates (on the side below a rotation axis P), the speed of the air flowing along the lower portion of the vehicle 100 increases. This reduces the airflow from the bottom to the top in the tire casing 101, thereby suppressing the upward air pressure. As a result, lift can be suppressed.By suppressing lift (the lift-reducing property), a downward force is increased, ground contact of the pneumatic tire 1 is improved, and steering stability is improved, which is an indicator of the driving performance of the vehicle 100. Furthermore, when the pneumatic tire 1 rotates, a boundary layer of turbulent flow is generated in the upper portion of the pneumatic tire 1 (on the side above the rotation axis P). This promotes airflow around the pneumatic tire 1. As a result, the spreading of the air flowing along is suppressed, so that the air resistance of the pneumatic tire 1 can be reduced. The reduction in air resistance leads to an improvement in the fuel consumption of the vehicle 100. As shown in FIG. Fig. 25, this effect can be obtained by adjusting the inclination of the raised portions 9 with respect to the tire circumferential direction and the tire radial direction relative to Fig. 24 is reversed.

[0063] Furthermore, according to the pneumatic tire 1 of the present embodiment, in the land portion 9 provided in the extending direction intersecting the tire circumferential direction and the tire radial direction, the center portion 9A includes the highest point hH of the protrusion height h from the tire side surface Sa, and the tip portions 9B provided on both sides of the center portion 9A in the extending direction each include the lowest point hL of the protrusion height h from the tire side surface Sa. Accordingly, the mass of the land portion 9 is smaller at the tip portions 9B. As a result, a sudden change in the mass from the tire side surface Sa is prevented in the area near the tip portions 9B of the land portion 9, thereby improving the uniformity in the tire circumferential direction, and thereby improving the uniformity.

[0064] Furthermore, according to the pneumatic tire 1 of the present embodiment, the central portion 9A in the land portion 9, which includes the highest point hH of the protrusion height h, is located just outward from the widest point of the tire H in the tire radial direction. Thus, the air resistance is reduced at the widest point of the tire H, where the pneumatic tire 1 is widest in the tire transverse direction, thereby also making the air resistance high there. As a result, the air resistance is further reduced.

[0065] Furthermore, according to the pneumatic tire 1 of the present embodiment, since the ratio of the total width SW to the outer diameter OD satisfies the relationship SW / OD ≤ 0.3, the total width is smaller and the outer diameter is larger than that of a typical pneumatic tire. Thus, the rolling resistance and air resistance during driving can be reduced. While large-diameter tires in particular tend to have increased air resistance caused by the failure to generate turbulent airflow due to a decrease in the relative speed between the side portion on the upper portion of the tire (the upper position on the tire side portion S when the tire is mounted on a vehicle) and the air, the pneumatic tire 1 of the present embodiment has a land portion 9 and satisfies the relationship of the ratio of the total width SW to the outer diameter OD.Thus, the air flow at the side portion can be swirled at the upper portion of the tire, thereby maintaining an effect of reducing air resistance.

[0066] Thus, the pneumatic tire 1 of the present embodiment can provide reduced lift and drag while maintaining good uniformity.

[0067] In the pneumatic tire 1 of the present embodiment, the center portion 9A and the tip portions 9B of the land portion 9 are preferably arranged outward from the widest part of the tire H in the tire radial direction.

[0068] According to the pneumatic tire 1, since the tip portions 9B are not arranged beyond the widest part of the tire H, the air resistance is reduced at the widest part of the tire H, where the pneumatic tire 1 is widest in the tire transverse direction, and the air resistance is also high there. As a result, the effect of significantly reducing the air resistance can be achieved.

[0069] In addition, as in Fig. 5, in the pneumatic tire 1 of the present embodiment, according to the invention, the change in the mass of the land portion 9 in the tire circumferential direction per 1 degree in the tire circumferential direction, divided by lines extending from the rotation axis P in the tire radial direction, is 0.1 g / degree or less.

[0070] According to the pneumatic tire 1, by specifying the change in the mass of the land portion 9 in the tire circumferential direction, the uniformity in the tire circumferential direction is improved. As a result, the effect of significantly improving the uniformity can be achieved.

[0071] Furthermore, in the pneumatic tire 1 of the present embodiment, the central portion 9A of the land portion 9 preferably has a protrusion height h in the range of 1 mm to 10 mm.

[0072] If the protrusion height h of the central portion 9A is less than 1 mm, the effect of accelerating the airflow flowing along the lower portion of the vehicle 100 and generating a boundary layer of turbulent flow is difficult to achieve. If the protrusion height h of the central portion 9A is greater than 10 mm, the amount of airflow colliding with the lobe portion 9 is increased. As a result, air resistance is likely to increase. Therefore, in order to achieve the effect of significantly reducing lift and drag, the protrusion height h of the central portion 9A is preferably in the range of 1 mm to 10 mm.

[0073] As with the Fig. 1, the raised portion 9 preferably protrudes 5 mm or less beyond a tire cross-sectional width HW at the widest point of the tire H when mounted on a normal rim, inflated to the normal internal pressure, and in an unloaded state. In other words, the protrusion dimension G by which the raised portion 9 protrudes outward in the tire transverse direction is, as shown in Fig. 26, from a reference line HL extending in the tire radial direction based on the widest point of the tire H of the tire side surface Sa, preferably 5 mm or less.

[0074] When the land portion 9 protrudes outward in the tire transverse direction from the tire section width HW at the widest point of the tire H by more than 5 mm, the amount of airflow colliding with the land portion 9 is increased. As a result, the air resistance of the land portion 9 is likely to increase. Thus, by specifying the range in which the land portion 9 protrudes outward in the tire transverse direction from the tire section width HW at the widest point of the tire H, an increase in air resistance caused by the land portion 9 can be suppressed, and the effect of the land portion 9 significantly improving the low-speed airflow can be obtained.In order to achieve these effects to a significant extent, the raised portion 9 preferably does not protrude in the tire transverse direction beyond the tire section width HW at the widest point of the tire H and may protrude 0 mm or less.

[0075] As in Fig. 27 to 29, the pneumatic tire 1 of the present embodiment has a groove 9E preferably formed in the surface of the land portion 9.

[0076] According to the pneumatic tire 1, the rigidity of the land portion 9 is reduced because the groove 9E is formed. As a result, a decrease in ride comfort due to the tire side portion S being made into a rigid structure by the land portions 9 can be suppressed. In addition, by forming the groove 9E, the mass of the land portion 9 is reduced. As a result, the uniformity of the tire side portion S can be suppressed by the land portions 9.

[0077] Note that a plurality of the grooves 9E are provided at predetermined intervals with respect to the length L, as shown in Fig. 27, so that they intersect the extending direction of the raised portion 9. An angle θ at which the grooves 9E intersect the extending direction of the raised portion 9 is not particularly specified. However, the grooves 9E preferably have the same angle θ so that an extreme change in the mass of the raised portion 9 in the extending direction is suppressed. As shown in Fig. 29, the grooves 9E preferably have the same angle θ (for example, θ = 90°) with respect to a tangent GL of a center line SL passing through the center of the ridge portion 9 in the transverse direction, so that an extreme change in the mass of the ridge portion 9 in the extending direction is suppressed. The grooves 9E preferably have a groove width of 2 mm or less, so that they have little aerodynamic influence, that is, their influence on the effect of enhancing the airflow along the lower portion of the vehicle 100 and generating a boundary layer of turbulent flow is minimal. As shown in Fig. 28, the grooves 9E preferably have a groove depth d1 equal to or less than the protrusion height h of the ridge portion 9, so that the ridge portion 9 is not divided halfway along the ridge portion 9, and the effect of enhancing the airflow along the lower portion of the vehicle 100 and generating a boundary layer of turbulent flow can be obtained. For example, the groove depth d1 of the grooves 9E is preferably equal to or less than 90% of the protrusion height h of the ridge portion 9. Note that the triangular shape of the ridge portion 9, viewed in a cross section in the transverse direction in Fig. 28, is just one example.

[0078] As in Fig. 30 and Fig. 31, the pneumatic tire 1 of the present embodiment has a depressed portion 9F preferably formed in the surface of the land portion 9.

[0079] According to the pneumatic tire 1, the rigidity of the land portion 9 is reduced by forming the depressed portion 9F. As a result, a decrease in ride comfort due to the tire side portion S being made into a rigid structure by the land portions 9 can be suppressed. In addition, by forming the depressed portion 9F, the mass of the land portion 9 is reduced. As a result, a decrease in uniformity due to the land portions 9 increasing the mass of the tire side portion S can be suppressed.

[0080] Note that a plurality of the recessed portions 9F are provided at predetermined intervals in the extending direction of the raised portion 9, as shown in Fig. 30. In embodiments in which the width W of the raised portion 9 changes in the extending direction, the recessed portions 9F preferably change their size according to the change in the width W, so that an extreme change in the mass of the raised portion 9 in the extending direction is suppressed. The recessed portions 9F preferably have an opening diameter of 2 mm or less, so that they have little aerodynamic influence, that is, their influence on the effect of enhancing the airflow along the lower portion of the vehicle 100 and generating a boundary layer of turbulent flow is minimal. As shown in Fig. 31, the recessed portions 9F preferably have a groove depth d2 equal to or less than the protrusion height h of the land portion 9, so that the land portion 9 is not divided halfway along the land portion 9, and the effect of enhancing the airflow along the lower portion of the vehicle 100 and generating a boundary layer of turbulent flow can be obtained. For example, the groove depth d2 of the recessed portions 9F is preferably equal to or less than 90% of the protrusion height h of the land portion 9. Note that the triangular shape of the land portion 9, viewed in a cross-section in the transverse direction in Fig. 31 is only one example. Furthermore, the position where the recessed portions 9F are provided is not limited to the upper portion of the land portion 9 and may be located at a side portion. The opening shape and the depth shape of the recessed portion 9F are not limited to a circular shape and may have various shapes. However, the opening edge and the bottom portion are preferably arc-shaped so that they are not elements that tend to generate cracks in the land portion 9.

[0081] As in Fig. 32, the grooves 9E and the depressed portions 9F in the pneumatic tire 1 of the present embodiment are preferably formed in the surface of the land portion 9.

[0082] According to the pneumatic tire 1, the rigidity of the land portion 9 is reduced because the grooves 9E and the depressed portion 9F are formed. As a result, a decrease in ride comfort due to the tire side portion S being made into a rigid structure by the land portions 9 can be suppressed. In addition, by forming the grooves 9E and the depressed portion 9F, the mass of the land portion 9 is reduced. As a result, a decrease in uniformity due to the land portions 9 increasing the mass of the tire side portion S can be suppressed.

[0083] Note that the grooves 9E and the recessed portions 9F in Fig. 32 are provided alternately in the direction of extension of the raised portion 9, but this is not intended as a limitation and they may be arranged in any suitable mixed manner.

[0084] In the pneumatic tire 1 of the present embodiment, the land portions 9 are preferably arranged at uneven intervals in the tire circumferential direction.

[0085] According to the pneumatic tire 1, by counteracting the periodicity of the land portions 9 in the tire circumferential direction with respect to the airflow along the tire side surface Sa of the tire side portion S, the difference in frequency disperses and equalizes the sound pressure generated by the land portions 9. As a result, noise (sound pressure level) can be reduced.

[0086] Note that the pitches of the land portions 9, viewed from the side of the pneumatic tire 1, are given as angles between auxiliary lines (not shown) of the land portions 9, the auxiliary lines being drawn from the rotation axis P to the ends 9D of the land portions 9 in the tire radial direction.In addition, in order to make the intervals between the land portions 9 uneven, various measures may be taken, such as maintaining the shape (projection height h, width W, and length L in the extending direction) of the land portions 9 and the inclination at which the land portions 9 intersect the tire circumferential direction and the tire radial direction while changing the pitch in the tire circumferential direction; changing the shape (projection height h, width W, and length L in the extending direction); and changing the inclination at which the land portions 9 intersect the circumferential direction and the tire radial direction.

[0087] Further, the pneumatic tire 1 of the present embodiment, when mounted on the vehicle, has a prescribed orientation with respect to the vehicle inside / outside, and the tire circumferential direction land portions 9 are preferably formed at least on the tire side portion S corresponding to the vehicle outside.

[0088] In other words, the orientation of the pneumatic tire 1 of the present embodiment when mounted on the vehicle 100 (see Fig. 24 and Fig. 25), with respect to the inside and outside of the vehicle 100 in the tire transverse direction. The prescribed orientation is not shown in the drawings, but may be indicated, for example, by indications provided on the sidewall portions 4. Therefore, the side facing the inside of the vehicle 100 when mounted on the vehicle 100 is the “vehicle inside,” and the side facing the outside of the vehicle 100 is the “vehicle outside.” It should be noted that the vehicle inside and vehicle outside markings are not limited to cases when mounted on the vehicle 100. For example, in cases where the pneumatic tire 1 is mounted on a rim, the orientation of the rim 50 (see Fig. 24 and Fig. 25) with respect to the inside and outside of the vehicle 100 in the tire width direction. Therefore, in cases where the pneumatic tire 1 is mounted on a rim, the orientation with respect to the inside and outside of the vehicle in the tire transverse direction is required.

[0089] The tire side portion S on the vehicle outer side is exposed to the outside of the tire housing 101 when the pneumatic tire 1 is mounted on the vehicle 100. By providing the raised portions 9 on the tire side portion S on the vehicle outer side, the airflow can be forced toward the vehicle outer side. This can achieve the effect of significantly reducing lift and drag.

[0090] Note that, in the pneumatic tire 1 of the above-described embodiment, the land portion 9 preferably has the width W in the transverse direction ranging from 0.5 mm to 10.0 mm. When the width W of the land portion 9 in the transverse direction is smaller than the above-described range, the area of ​​the land portion 9 that comes into contact with the airflow is small. As a result, the effect of the land portions 9 improving the low-speed airflow is difficult to obtain. When the width W of the land portion 9 in the transverse direction is larger than the above-described range, the area of ​​the land portion 9 that comes into contact with the airflow is large. This causes the land portions 9 to increase air resistance and increase the tire weight.By appropriately adjusting the width W of the ridge portion 9 in the transverse direction, the effect that the ridge portions 9 significantly improve the slow airflow can be obtained.

[0091] Furthermore, the pitch of the land portions 9 in the tire circumferential direction may be the same as or different from the pitch of lug grooves in the tread portion 2 in the tire circumferential direction. By making the pitch of the land portions 9 in the tire circumferential direction different from the pitch of the lug grooves in the tread portion 2 in the tire circumferential direction, sound pressure generated by the land portions 9 and sound pressure from the lug grooves are dispersed and counteract each other due to the different frequencies. As a result, the pattern noise generated by the lug grooves can be reduced. Note that the lug grooves having a different pitch than the land portions 9 in the tire circumferential direction include all the lug grooves in the rib-like land portions 23 formed by the main grooves 22 in the tire transverse direction.However, in order to obtain the effect of significantly reducing the pattern noise generated from the lug grooves, the pitch of the land portions 9 in the tire circumferential direction is preferably different from the pitch of the laterally outermost lug grooves located closest to the land portions 9. Examples

[0092] For example, tests on lift reduction performance, drag reduction performance, uniformity, bump section consistency, ride comfort and sound pressure level reduction performance were conducted on pneumatic tires with different configurations (see Fig. 33).

[0093] In the lift reduction performance and drag reduction performance test, a wind tunnel simulation test was conducted using a vehicle model with tire models mounted on a vehicle body model of a motor-assisted passenger car.

[0094] The driving speed was set to the equivalent of 80 km / h. Using fluid analysis software, the aerodynamic properties (lift reduction performance and drag reduction performance) were obtained using Lattice Boltzmann methods, for which the drag coefficient was used. The evaluation results are expressed as index values ​​based on the obtained results, with the results of the prior art example defined as the reference value (100). In the evaluation, higher values ​​indicate better lift reduction performance and better drag reduction performance.

[0095] In the uniformity tests, the test tires were inflated to normal internal pressure. The test tires were then measured for radial force variation (LFV) according to the method specified in JASO C607 (Test Procedures for Automobile Tire Uniformity). Evaluations were performed by expressing the measurement results as index values, with the results of the prior art example defined as the reference value (100). Higher scores indicate better uniformity.

[0096] In the bump durability performance tests, using an indoor drum endurance test, the test tires were rotated at a speed of 240 km / h for a specified period of time while monitoring the condition of the bumps. The absence of cracks and failure of the bumps is required, with "pass" indicating the absence of cracks and failure of the bumps, and "fail" indicating cracks or failure of the bumps.

[0097] In the ride comfort test, the test tires were mounted on the test vehicle, and the test vehicle was driven at 50 km / h on a straight test track with 10 mm undulations. Three members of a panel of testers conducted a feel test for ride comfort. In the evaluation, the average values ​​of three test results are expressed as index values, with the result of the prior art example defined as the reference value (100). In the evaluation, higher values ​​indicate better ride comfort.

[0098] In the sound pressure reduction performance test, the test tires were mounted on the test vehicle, and the sound pressure level of external noise (the sound pressure reduction performance) was measured when the test vehicle was driven at a speed equivalent to 80 km / h. The evaluation values ​​are expressed as index values ​​based on the measurement results, with the result of the prior art example defined as the reference value (100). In the evaluation, higher index values ​​indicate better sound pressure reduction performance.

[0099] Referring to Fig. 33, the pneumatic tire of the prior art example has a ratio SW / OD of the total width SW to the outer diameter OD of 0.33, the configuration shown in Fig. 34, and includes a raised portion 10 provided on the tire side portion S. The raised portion 10 has a triangular shape when viewed in a cross section in the transverse direction, as shown in Fig. 13, extends in the tire radial direction, has a uniform protrusion height in the extending direction and width in the transverse direction, is arranged in a direction intersecting the widest part of the tire H, and is arranged at equal intervals in the tire circumferential direction.

[0100] Furthermore, with reference to Fig. 33, the pneumatic tire of Comparative Example 1 has a ratio SW / OD of the total width SW to the outer diameter OD of 0.24, but provides protrusions similar to those of the prior art example. The pneumatic tire of Comparative Example 2 has the Fig. 5 shown configuration and closes the Fig. 7 shown elevation section with a triangular shape when viewed in a cross-section in the transverse direction of the elevation section, as in Fig. 13; however, the ratio SW / OD of the total width SW to the outer diameter OD is 0.33.

[0101] Furthermore, with reference to Fig. 33 the pneumatic tyres of Examples 1 to 11 have a ratio SW / OD of the total width SW to the outer diameter OD of 0.24, which in Fig. 5 shown configuration and close the Fig. 7 shown elevation section with a triangular shape, as in a cross-section of the Fig. 13 in the transverse direction. The pneumatic tire of Example 12 has the Fig. 8 shown configuration and closes the Fig. 7 shown elevation section with a triangular shape when viewed in a cross-section in the transverse direction of the elevation section, as in Fig. 13. From other perspectives, the examples are given as appropriate.

[0102] As can be seen from the test results of Fig. 33, the pneumatic tires of the examples have excellent lift reduction performance, drag reduction performance, uniformity, consistency of bump portions, ride comfort, and sound pressure level reduction performance. List of reference symbols 1 pneumatic tire 9 Survey section 9A Middle Section 9B peak section 9E groove 9F In-depth section S Tire side section Sa tire sidewall SW total width OD outer diameter

Claims

[1] Pneumatic tyre (1), comprising: a plurality of elevation portions (9) extending along a tire side surface (Sa) of a tire side portion (S) in a direction intersecting a tire circumferential direction and a tire radial direction; the plurality of survey sections (9), each of which includes: a central portion (9A) in a direction of extension, which includes a highest point (hH) of a projection height (h) from the tire side surface (Sa), and in the direction of travel, tip portions (9B) on each side of the central portion (9A) enclosing a lowest point (hL) of a projection height (h) from the tire side surface (Sa), wherein at least the central portion (9A) is arranged in the tire radial direction only outwardly from a widest point (H) of the tire; and where a ratio of a total width SW to an outer diameter OD satisfies the relationship SW / OD ≤ 0.3, wherein a ratio of an inner diameter RD to the outer diameter OD satisfies the relationship RD / OD ≥ 0.7, and wherein a change in the mass of the bump portion (9) in the tire circumferential direction per 1 degree in the tire circumferential direction is 0.1 g / degree or less. [2] A pneumatic tire according to claim 1, wherein the central portion (9A) and the tip portions (9B) of the land portion (9) are arranged outward in the tire radial direction from the widest point (H) of the tire. [3] A pneumatic tire according to claim 1 or 2, wherein the central portion (9A) of the land portion (9) has a projection height (h) in a range of 1 mm to 10 mm. [4] A pneumatic tire according to any one of claims 1 to 3, wherein the land portion (9) protrudes 5 mm or less in a tire transverse direction from a tire cross-sectional width at the widest point (H) of the tire when the pneumatic tire (1) is mounted on a normal rim, inflated to a normal internal pressure, in an unloaded state, and viewed in a meridian cross-section. [5] A pneumatic tire according to any one of claims 1 to 4, wherein a groove (9E) is formed on a surface of the land portion (9). [6] A pneumatic tire according to any one of claims 1 to 5, wherein a depressed portion (9F) is formed on the surface of the land portion (9). [7] A pneumatic tire according to any one of claims 1 to 6, wherein the plurality of land portions (9) are arranged at uneven intervals in the tire circumferential direction. [8] A pneumatic tire according to any one of claims 1 to 7, wherein an orientation with respect to a vehicle inside / outside is prescribed when the pneumatic tire (1) is mounted on a vehicle (100), and the plurality of land portions (9) are formed at least on a tire side portion (S) corresponding to a vehicle outside.

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