pneumatic tires

Abstract

Pneumatic tires (10), including: a pair of left and right bead sections (12); side wall sections (14) connected to an outer surface in the radial direction of the bead sections (12); a running surface section (16) extending between the side wall sections (14); a carcass (22), including at least one carcass ply extending in a torus shape between the pair of left and right bead sections (12); a belt (24), including at least one belt layer (24a, 24b, 24c) arranged on an outer surface in a tire radial direction of the carcass (22) and enclosing cord threads; and a tread rubber (26) arranged on an outer side in the tire radial direction of the belt (24) and forming a section of the tread section (16), in a state in which the pneumatic tire (10) is mounted on a normal rim and inflated to 5% of a specified internal pressure, when a tread width is TW and a total tire width is SW in a tire meridian cross-sectional view, a relationship of 0.80 ≤ TW / SW ≤ 0.95 is satisfied, and when a ground contact width at a load of 100% of a maximum load capacity is CW100 and a ground contact width at a load of 70% of the maximum load capacity is CW70, a relationship of 1.04 ≤ CW100 / CW70 ≤ 1.15 is satisfied.

Description

Technical area

[0001] The present invention relates to a pneumatic tire having reduced rolling resistance in a normal load condition and improved dry braking performance. State of the art

[0002] Various techniques have been proposed to reduce rolling resistance, which is an important factor for lower fuel consumption and the like.

[0003] For example, a technique for reducing the thickness of a rubber forming a shoulder portion has been proposed to achieve lightweight performance and thus reduce rolling resistance (JP 5469692 B2). Furthermore, a technique has been proposed in which the ratio TR3 / TR2 of the curvature radius TR3 at 300 kPa—the high internal pressure setting—to the curvature radius TR2 at 230 kPa—the internal pressure approaching normal internal pressure—and the specified tire inflation pressure for a passenger car is set to 1.10 to 1.50, so that the center tread portion TC curves in a well-balanced manner even when the tire is inflated to a high internal pressure to reduce rolling resistance (JP 5952587 B2). The prior art also includes the documents EP 3 023 270 B1, EP 3 132 950 B1, DE 11 2017 003 571 T5 and DE 11 2014 002 102 T5. Brief description of the inventionTechnical problem

[0004] In recent years, there has been an increasing demand for faster and more accurate stopping in a braking load condition, as well as reduced rolling resistance under normal load and lower fuel consumption performance.

[0005] From this perspective, as in the case of the technique of JP 5469692 B2, if the thickness of the rubber constituting the shoulder portion is reduced, sufficient ground contact is ensured. Thus, there is a risk that sufficient frictional force may not be achieved under a braking load condition. If the ratio TR3 / TR2 is set to 1.10 to 1.50, as in the technique in JP 5952587 B2, the tread center portion TC bulges excessively when inflated to the specified air pressure or higher. Thus, there is a risk that sufficient ground contact width may not be ensured and sufficient frictional force may not be achieved under a braking load condition. As described above, there is room for improvement in JP 5469692 B2 and JP 5952587 B2 in increasing the frictional force under a braking load condition and improving dry braking performance.

[0006] In view of the foregoing, it is an object of the present invention to provide a pneumatic tire having reduced rolling resistance under normal load conditions and improved dry braking performance. Solution to the problem

[0007] The pneumatic tire according to the invention includes a pair of left and right bead portions; sidewall portions connected to an outer side in a radial direction of the bead portions; a tread portion extending between the sidewall portions; a carcass including at least one carcass ply extending in a toroidal shape between the pair of left and right bead portions; a belt including at least one belt layer disposed on an outer side in a tire radial direction of the carcass and including cords;and a tread rubber disposed on an outer side in the tire radial direction of the belt and constituting a portion of the tread portion, in a state where the pneumatic tire is mounted on a normal rim and inflated to 5% of a predetermined internal pressure, when a tread width is W and a total tire width is SW in a tire meridian cross-sectional view, a relationship of 0.80 ≤ TW / SW ≤ 0.95 is satisfied, and when a ground contact width at a load of 100% of a maximum load capacity is CW100 and a ground contact width at a load of 70% of the maximum load capacity is CW70, a relationship of 1.04 ≤ CW100 / CW70 ≤ 1.15 is satisfied.; Advantageous effects of the invention

[0008] In the pneumatic tire according to an embodiment of the present invention, improvements are added to the ratio of the tread width to the total tire width and the ratio of the ground contact width in the braking load state to the ground contact width in the normal load state. As a result, according to the pneumatic tire according to an embodiment of the present invention, it is possible to improve the rolling resistance in the normal load state and the dry braking performance in a balanced manner. Brief description of the drawings Fig. 1 is a meridian cross-sectional view illustrating a pneumatic tire according to an embodiment of the present invention. Fig. 2 is a tire meridian cross-sectional view of the Fig.1, illustrating only one side in the tire width direction of an equatorial plane of the tire CL extending from a sidewall portion to a tread portion. Fig. 3 is a tire meridian cross-sectional view of the Fig. 1, illustrating only one side in the tire width direction from the equatorial plane of the tire CL extending from a tread portion to a shoulder portion. Fig. 4 is a tire meridian cross-sectional view of the Fig. 1, illustrating only one side in the tire width direction of the tire equatorial plane CL extending from the tread portion to the shoulder portion. Fig. 5 is a tire meridian cross-sectional view of the Fig.1, illustrating only one side in the tire width direction from the tire equatorial plane CL extending from the bead portion to the tread portion. Fig. 6 is a tire meridian cross-sectional view of the Fig. 1, illustrating only one side in the tire width direction of the tire equatorial plane CL extending from the tread portion to the shoulder portion. Description of embodiments

[0009] Pneumatic tires according to embodiments (including the basic embodiments and additional embodiments 1 to 8) of the present invention will be described below based on the drawings. Note that the present invention is not limited to these embodiments. Components of the embodiments include components that are substantially identical or that can be substituted or easily conceived by a person skilled in the art. Furthermore, various modes described in this embodiment can be combined as desired by those skilled in the art within the scope of obviousness. Basic embodiment

[0010] The following is a description of the basic mode of the pneumatic tire according to an embodiment of the present invention. Herein, "tire radial direction" refers to the direction perpendicular to the rotation axis of the pneumatic tire. "Tire radial inward" refers to the direction facing the rotation axis in the tire radial direction. "Tire radial outward" refers to the direction away from the rotation axis in the tire radial direction. "Tire circumferential direction" refers to the circumferential direction, with the center axis being the rotation axis.In addition, "tire width direction" refers to a direction parallel to the rotation axis; "tire width direction inner side" refers to a side facing the tire's equatorial plane (tire equator line) in the tire width direction; and "tire width direction outer side" refers to a side farther from the tire's equatorial plane in the tire width direction. Note that "tire equatorial plane" refers to the plane perpendicular to the tire's rotation axis and passing through the tire's center width.

[0011] Fig.1 is a meridian cross-sectional view illustrating a pneumatic tire according to an embodiment of the present invention. A pneumatic tire 10 illustrated in the same drawing includes a pair of left and right bead portions 12, sidewall portions 14 connected to radially outer sides of the bead portions 12, and a tread portion 16 extending between the sidewall portions 14.

[0012] The Fig.1 includes a carcass 22 including at least one carcass ply (one carcass ply is shown in the same drawing) extending in a torus shape between the pair of left and right bead portions 12 and 12, a belt 24 including at least one belt layer 24a to 24c (three layers are shown in the same drawing) disposed on the outer side in the tire radial direction of the carcass 22 and including cords, and a tread rubber 26 disposed on the outer side in the tire width direction of the belt 24 and constituting a portion of the tread portion 16.

[0013] Under the assumptions described above, the pneumatic tire 10 satisfies in a state in which the pneumatic tire 10 is mounted on a normal rim and inflated to 5% of a predetermined internal pressure as shown in Fig.1, satisfies a relationship of 0.80 ≤ TW / SW ≤ 0.95 when the tread width is TW and the tire total width is SW in a tire meridian cross-sectional view, and a relationship of 1.04 ≤ CW100 / CW70 ≤ 1.15 when the ground contact width (a dimension in the tire width direction of the ground contact surface) at a load of 100% of the maximum load capacity is CW100 and the ground contact width at a load of 70% of the maximum load capacity is CW70.

[0014] Here, "specified rim" refers to an "applicable rim" as defined by the Japan Automobile Tire Manufacturers Association (JATMA), a "design rim" as defined by the Tire and Rim Association (TRA), and a "measuring rim" as defined by the European Tire and Rim Technical Organization (ETRTO). Furthermore, "specified internal pressure" refers to a "maximum air pressure" as defined by JATMA, the maximum value in "tire load limits at various cold inflation pressures" as defined by the TRA, and "inflation pressures" as defined by the ETRTO.In addition, “maximum load capacity” refers to the “maximum load capacity” as defined by JATMA, the maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” as defined by TRA or “LOAD CAPACITY” as defined by ETRTO. Effects

[0015] In general, it is desirable to reduce the ground contact area and thus rolling resistance in a normal load condition to reduce fuel consumption. On the other hand, it is desirable to increase the ground contact area and improve braking performance in a braking load condition to achieve reliable stopping.

[0016] In the present embodiment, improvements are added to the ratio between the tread width TW and the tire overall width SW and the ratio of the ground contact width CW100 in the braking load condition to the ground contact width CW70 in the normal load condition.

[0017] By setting the ratio TW / SW of the tread width TW to the overall tire width SW to 0.80 or more, a sufficient ground contact width and a sufficient ground contact area of ​​the so-called shoulder portion 18 at or near the boundary between the sidewall portion 14 and the tread portion 16 can be ensured, and the friction force in the braking load state can be increased (Effect 1). In contrast, by setting the ratio TW / SW of the tread width TW to the overall tire width SW to 0.95 or less, the ground contact pressure at the shoulder portion 18 is not excessive, and the rolling resistance in the normal load state can be reduced (Effect 2).

[0018] It should be noted that the ratio TW / SW of the tread width TW to the total tire width SW is preferably set to 0.83 or more and 0.92 or less, and more preferably to 0.85 or more and 0.90 or less.

[0019] By setting the ratio CW100 / CW70 of the ground contact width (ground contact width in the braking load condition) CW100 at a load of 100% of the maximum load capacity to the ground contact width (ground contact width in the normal load condition) CW70 at a load of 70% of the maximum load capacity to 1.04 or more, sufficient ground contact width can be ensured in the braking load condition, thus increasing the friction force in the braking load condition (Effect 3). In contrast, by setting the ratio CW100 / CW70 to 1.15 or less, the rolling resistance in the braking load condition can be reduced without excessively increasing the ground contact length (a dimension in the tire circumferential direction in the ground contact condition) in the braking load condition (Effect 4).

[0020] It should be noted that the ratio CW100 / CE70 of the ground contact width CW100 to the ground contact width CW70 is preferably set to 1.06 or more and 1.13 or less, and more preferably set to 1.08 or more and 1.11 or less.

[0021] As described above, in the pneumatic tire according to the present embodiment, since improvements are added to the TW / SW ratio and the CW100 / CW70 ratio, it is possible to reduce the rolling resistance in the normal load loading state due to Effect 2, and it is possible to increase the friction force in the braking load loading state and thus the dry braking performance due to the combination of Effects 1, 3 and 4.

[0022] The pneumatic tire according to the present embodiment is obtained through various general manufacturing processes, in other words, a step of mixing tire materials, a step of processing the tire materials, a step of molding a green tire, a vulcanization step, a post-vulcanization inspection step, and the like. In manufacturing the pneumatic tire according to the present embodiment, for example, land portions and recess portions corresponding to grooves and land portions formed in the Fig. 1 are formed in the inner wall of a vulcanization mold, and vulcanization is carried out using this mold. Additional embodiments

[0023] Descriptions will now be given of additional embodiments 1 to 9 which can be optionally implemented instead of the basic embodiment of the pneumatic tire according to the present invention described above. Additional embodiment 1

[0024] Fig. 2 is a tire meridian cross-sectional view of the Fig. 1 of the pneumatic tire of the present embodiment, which illustrates only one side in the tire width direction from the equatorial plane of the tire CL, which extends from the sidewall portion 14 to the tread portion 16. In the basic embodiment, as shown in the Fig. 1 and Fig.2, it is desirable that when the tire radial direction dimension between an outermost point P1 of the equatorial plane of the tire CL in the tire radial direction and an end point P2 of the tread rubber 26 in the tire width direction is D, a tire section height is SH, a tire radial direction height up to the position of the maximum tire width is SWH, and the radius of curvature of the arc of the shoulder portion is R1, a relationship of TW × 0.04-(SWH / SH - 0.5) × 15 ≤ D ≤ TW × 0.07-(SWH / SH - 0.5) × 15 is satisfied, a relationship of 5 mm ≤ R1 ≤ 30 mm is satisfied, the ratio BW / TW of the width BW of the effective belt layer 24c to the tread width TW has a relationship of 0.80 ≤ BW / TW ≤ 0.90, and the belt cover 28 is formed on the outer side in the tire width direction of the belt layer 24a with the maximum width (additional embodiment 1). It should be noted that in the Fig.2, the belt cover 28 includes two belt cover layers 28a and 28b connected in the tire radial direction.

[0025] Here, "tire section height SH" refers to the tire radial direction dimension from a portion of contact between the bead portion 12 and the rim to the outermost position of the tread portion 16 in the tire radial direction. "Tire radial direction height SWH" to the tire maximum width position refers to the tire radial direction dimension from a portion of contact between the bead portion 12 and the rim to the tire maximum width position. The arc of the shoulder portion refers to an arc forming the outer contour of the shoulder portion 18, which is in the Fig. 1 and Fig. 2 is illustrated.

[0026] "Effective belt layer" refers to the belt layer 24c whose outermost position in the tire width direction is located on the innermost side in the tire width direction among the belt layers (24a, 24b and 24c) constituting the belt 24.

[0027] By setting the tire radial direction dimension D to [TW × 0.04 - (SWH / SH - 0.5) × 15] or more, the rolling resistance in the normal load loading state can be further reduced without excessively increasing the ground contact width (the tire width direction dimension in the ground contact state).

[0028] In contrast, by setting the tire radial direction dimension D to be equal to or less than [TW × 0.04 - (SWH / SH - 0.5) × 15], a sufficient ground contact width and thus a sufficient ground contact area of ​​the shoulder portion can be ensured, the friction force in the braking load loading state can be further increased, and thus the dry braking performance can be further improved.

[0029] By setting the radius of curvature R1 of the arc of the shoulder portion to 5 mm or more, the rolling resistance in the normal load loading state can be further reduced without excessively increasing the ground contact width (a dimension in the tire width direction in the ground contact state).

[0030] In contrast, by setting the radius of curvature R1 of the arc of the shoulder portion to 30 mm or less, a sufficient ground contact width and thus a sufficient ground contact area of ​​the shoulder portion can be ensured, the friction force in the braking load state can be further improved, and the dry braking performance can be further increased.

[0031] It should be noted that the radius of curvature R1 is more preferably 8 mm or more and 27 mm or less, and most preferably 10 mm or more and 25 mm or less.

[0032] Since the BW / TW ratio is 0.80 or more, the belt 24 can be sufficiently secured on the outer side in the tire width direction of the tread portion 16, and durability performance can be improved. On the other hand, since the BW / TW ratio is 0.90 or less, it is possible to prevent the belt 24 from becoming unnecessarily long.

[0033] It should be noted that the BW / TW ratio is more preferably 0.82 or more and 0.88 or less, and most preferably 0.83 or more and 0.87 or less.

[0034] Since the belt cover 28 is formed on the outer side in the tire width direction of the belt layer 24a with a maximum width, deflection of the shoulder portion 18 during tire rolling is suppressed, and occurrence of cracking originating from the end portion of the belt 24 can be suppressed. Additional embodiment 2

[0035] Fig. 3 is a tire meridian cross-sectional view of the Fig.1, illustrating only one side in the tire width direction from the equatorial plane of the tire CL extending from the tread portion 16 to the shoulder portion 18. In a basic embodiment and an embodiment in which the additional embodiment 1 is added to the basic embodiment, as shown in Fig.3, the tread portion 16 preferably includes at least two main grooves extending in the tire circumferential direction (in the same drawing, two main grooves 32a and 32b on one side in the tire width direction from the equatorial plane of the tire), and the tire width-direction center position P3 of the main groove 32b on the outermost side in the tire width direction among the main grooves 32a and 32b is preferably present at a position at a distance of 1 / 4 or less of the tread width TW from the tire equatorial plane CL (Additional Embodiment 2).

[0036] "Main groove" here refers to a groove in which a wear indicator must be provided according to JATMA and which typically has a width of 2% or more of the tread width TW. Furthermore, the tire width-direction center position P3 of the main groove 32b on the outermost side in the tire width direction refers to the tire width-direction center position of the groove bottom of the main groove 32b.

[0037] Since the center position P3 in the tire width direction of the main groove 32b is present on the outermost side in the tire width direction at a position at a distance of 1 / 4 or less of the tread width TW from the equatorial plane of the tire CL, a sufficient ground contact area of ​​the shoulder portion 18 can be ensured without forming the main groove on the tread surface near the shoulder portion 18, the friction force in the braking load loading state can be further increased, and thus the dry braking performance can be further increased.

[0038] It should be noted that the tire width direction center position P3 is more preferably located at a position at a distance of 23 / 100 or less of the tread width TW from the tire equatorial plane CL, and most preferably located at a position at a distance of 21 / 100 or less. Additional embodiment 3

[0039] Fig. 4 is a tire meridian cross-sectional view of the Fig. 1, illustrating only one side in the tire width direction from the equatorial plane of the tire CL extending from the tread portion 16 to the shoulder portion 18. In the basic embodiment or an embodiment in which at least one of the additional embodiments 1 and 2 is added to the basic embodiment, as shown in Fig.4, an outer contour 42 of the tread portion 16 preferably includes a center portion arc 42a located at a center portion in the tire width direction, and a pair of shoulder arcs 42b connected to the outer side in the tire width direction of the center portion arc 42a, and a relationship of 0.40 ≤ L / (TW / 2) ≤ 0.70 is preferably satisfied when the tire width direction length of the center portion arc 42a is 2L (Additional Embodiment 3). It should be noted that, although the center portion arc 42a in Fig. 4 is shown only in a section on one side of the equatorial plane of the tire CL, one half of which is actually present on the other side of the equatorial plane of the tire CL.

[0040] By setting the ratio L / (TW / 2) to 0.40 or more, the ground contact width and thus the ground contact area of ​​the shoulder portion can be further ensured, the friction force in the braking load state can be further improved, and the dry braking performance can be further increased.

[0041] In contrast, by setting the ratio L / (TW / 2) to 0.70 or less, the rolling resistance in the normal load loading condition can be further reduced without excessively increasing the ground contact width.

[0042] It should be noted that the ratio L / (TW / 2) is preferably 0.45 or more and 0.65 or less, and most preferably 0.50 or more and 0.60 or less. Additional embodiment 4

[0043] In the basic embodiment or an embodiment in which at least one of the additional embodiments 1 to 3 is added to the basic embodiment, it is preferable that the tire outer diameter is equal to or larger than the standard mean value (additional embodiment 4).

[0044] Here, "standard" refers to JATMA, TRA, or ETRTO, as described above. Furthermore, "standard mean" refers to a value located in the middle in a case where a plurality of outer diameters listed in JATMA or the like are arranged in ascending order.

[0045] By adjusting the tire outer diameter to be equal to or smaller than the standard mean value, in other words, by increasing the tire outer diameter to a certain extent, a sufficient volume of the cavity inside the tire can be ensured, both the deflection of the tire in the braking load loading condition and the deflection of the tire in the normal load loading condition can be reduced, and thus the rolling resistance in both load loading conditions can be reduced.

[0046] It should be noted that by setting the tire outer diameter to be equal to or larger than a value 3 mm smaller than the standard maximum value, the effect described above can be achieved at a higher level. Additional embodiment 5

[0047] In the basic embodiment or an embodiment in which at least one of the additional embodiments 1 to 4 is added to the basic embodiment, it is preferable that the tire total width is equal to or larger than a standard average value (additional embodiment 5).

[0048] Here, "standard" refers to JATMA, TRA, or ETRTO, as described above. Furthermore, "standard mean" refers to a value located in the middle in a case where a plurality of overall tire widths listed in JATMA or the like are arranged in ascending order.

[0049] By adjusting the total tire width to be equal to or smaller than the standard mean value, in other words, by increasing the tire outer diameter to a certain extent, a sufficient volume of the cavity inside the tire can be ensured, both the deflection of the tire in the braking load loading condition and the deflection of the tire in the normal load loading condition can be reduced, and thus the rolling resistance in both load loading conditions can be reduced.

[0050] It should be noted that by setting the total tire width to be equal to or greater than a value 3 mm smaller than the standard maximum value, the effect described above can be achieved at a higher level. Additional embodiment 6

[0051] Fig. 5 is a tire meridian cross-sectional view of the Fig.1 of the pneumatic tire of the present embodiment, which illustrates only one side in the tire width direction from the equatorial plane of the tire CL, which extends from the bead portion 12 to the tread portion 16. It should be noted that the Fig. 5 is a type in which the bead portion 12 includes a bead core 12a and a bead filler 12b formed on the outer side in the tire radial direction of the bead core 12a.

[0052] In a basic embodiment or an embodiment in which at least one of the additional embodiments 1 to 5 is added to the basic embodiment, as in Fig. 5, it is preferable that a relationship of 0.50 ≤ F1 / SH ≤ 0.80 is satisfied when the tire radial direction dimension from the belt edge P4 to the bead filler top P5 is F1 (Additional Embodiment 6).

[0053] By setting the ratio F1 / SH to 0.50 or greater, a region extending from the sidewall portion 14 to the shoulder portion 18, which is likely to be deformed due to the influence of a load, is sufficiently deflected. This can ensure a sufficient ground contact width and thus a sufficient ground contact area of ​​the shoulder portion, further improve the friction force under braking load conditions, and further enhance dry braking performance. In contrast, by setting the ratio F1 / SH to 0.80 or less, it is possible to suppress excessive deflection of the region. This can further reduce rolling resistance under normal load conditions without unnecessarily increasing the ground contact width.

[0054] It should be noted that the ratio F1 / SH is more preferably 0.55 or more and 0.75 or less, and most preferably 0.60 or more and 0.70 or less. Additional embodiment 7

[0055] In the basic embodiment or an embodiment in which at least one of Additional Embodiments 1 to 5 is added to the basic embodiment, it is preferable that a relationship of 0.50≤F2 / SH≤0.80 is satisfied when only the tire bead core is present in the bead portion, the bead filler is not present, and the tire radial direction dimension from the belt edge to the bead core is defined as F2 (Additional Embodiment 7). Note that this embodiment is a modified example of Additional Embodiment 6.

[0056] By setting the ratio F2 / SH to 0.50 or greater, a region extending from the sidewall portion 14 to the shoulder portion 18, which is likely to be deformed due to the influence of a load, is sufficiently deflected. This can ensure a sufficient ground contact width and thus a sufficient ground contact area of ​​the shoulder portion, further improve the friction force under braking load conditions, and further enhance dry braking performance. In contrast, by setting the ratio F2 / SH to 0.80 or less, it is possible to suppress excessive deflection of the region. This can further reduce rolling resistance under normal load conditions without unnecessarily increasing the ground contact width.

[0057] It should be noted that the ratio F2 / SH is more preferably 0.55 or more and 0.75 or less, and most preferably 0.60 or more and 0.70 or less. Additional embodiment 8

[0058] Fig. 6 is a tire meridian cross-sectional view of the Fig. 1, which illustrates only one side in the tire width direction from the equatorial plane of the tire CL, extending from the tread portion 16 to the shoulder portion 18. In the basic embodiment or an embodiment in which at least one of the additional embodiments 1 to 7 is added to the basic embodiment, as shown in Fig.6, preferably, a belt edge interval ES between the belt layer 24a having a maximum width and the belt layer 24c having a minimum width satisfies a relationship of 5 mm < ES < 15 mm (additional embodiment 8).

[0059] Here, "belt layer width" refers to the tire width-direction dimension of the belt layer. The belt edge distance ES refers to the distance between the outermost point in the tire width direction of the belt layer 24a with the maximum width and the outermost point in the tire width direction of the belt layer 24c with the minimum width.

[0060] By setting the belt edge pitch ES to more than 5 mm, it is possible to sufficiently ensure a region where only the belt layer with the maximum width exists in the outer portion in the tire width direction. This can sufficiently realize the deflection of the shoulder portion 18, and the ground contact width can be further reduced. As a result, the rolling resistance under normal load loading conditions can be further reduced.

[0061] In contrast, by setting the belt edge pitch ES to less than 15 mm, there is no excessively large area in the tire width direction where the belt layer with the maximum width is formed but the belt layer with the smallest width is not formed. Thus, the occurrence of cracks originating from the end portion of the belt 24 when the sidewall portion 14 is deflected can be further suppressed.

[0062] It should be noted that the belt edge spacing ES is more preferably 7 mm or more and 13 mm or less, and most preferably 8 mm or more and 12 mm or less. Additional embodiment 9

[0063] In the basic embodiment or an embodiment in which at least one of the additional embodiments 1 to 8 is added to the basic embodiment, it is preferable that a relationship of 4.5 mm ≤ GD ≤ 7.5 mm is satisfied when the depth of at least one main groove including the equatorial plane of the tire or one main groove (for example, the main grooves 32a and 32b shown in Fig. 3) which is closest to the equatorial plane of the tire among the main grooves GD (additional embodiment 9).

[0064] Here, the groove depth GD of the main groove refers to the dimension of the longest line segment from the tire tread line to the groove bottom under the vertical lines with respect to the tire tread line (the outer contour of the tire when the main groove is not present).

[0065] By setting the main groove depth (GD) to 4.5 mm or more, the wear life of the main groove can be sufficiently ensured until the main groove is worn and the wear indicator is exposed, thus maintaining the drainage performance for a long period of time. In contrast, by setting the main groove depth (GD) to 7.5 mm or less, it is possible to further reduce rolling resistance under normal load loading without unnecessarily increasing the amount of tread rubber.

[0066] It should be noted that the groove depth GD of the main groove is more preferably 5.0 mm or more and 7.0 mm or less, and most preferably 5.5 mm or more and 6.5 mm or less. Example

[0067] Pneumatic tires according to Examples 1 to 9 and Comparative Examples 1 to 3 with a tire size of 205 / 60R16 92 V and a Fig.1 (including bead fillers and bead cores in the bead portions) are manufactured. The detailed specifications of these pneumatic tires are shown in Tables 1 and 2 below. Note that in Tables 1 and 2, TW indicates the tread width, SW indicates the tire's overall width, CW100 indicates the ground contact width at a load of 100% of the maximum load capacity, CW70 indicates the ground contact width at a load of 70% of the maximum load capacity, D indicates a tire radial dimension between the outermost point in the tire's equatorial plane in the tire radial direction and the end point in the tire width direction of the tread rubber, SH indicates a tire section height, SWH indicates a tire radial height up to a tire maximum width position, and R1 indicates the radius of curvature of the arc of the shoulder portion.BW indicates the width of the effective belt layer, GC indicates the distance from the equatorial plane of the tire to a center position in the tire width direction of the outermost main groove in the tire width direction, L indicates the length of half the length in the tire width direction of the center section arc, F1 indicates a tire radial direction dimension from the belt edge to the bead filler top, ES indicates a belt edge inter-distance between the belt layer with the maximum width and the belt layer with the minimum width, and GD indicates the depth of the main groove.

[0068] Pneumatic tires of Examples 1 to 9 and Comparative Examples 1 to 3 thus prepared were evaluated for rolling resistance and dry braking performance according to the following methods. Rolling resistance

[0069] The test tires were mounted on wheels with a rim size of 16 × 6 J mounted on a drum testing machine, and a rolling resistance coefficient (RRC) was measured according to ISO 25280 under conditions of an air pressure of 210 kPa and an applied load of 4.94 kN. The evaluation results are shown by index values ​​relative to 100 of Comparative Example 1 using the reciprocals of the measured values. The higher the index value, the lower the rolling resistance. The results are also presented in Tables 1 and 2. Dry braking performance

[0070] The test tires were mounted on wheels with a rim size of 16 × 6 J, mounted on a passenger car, inflated to an air pressure (F / R) of 240 kPa / 240 kPa after warming up, and a braking distance from an initial speed of 100 km / h to a complete stop on dry road surfaces was measured. The evaluation results are shown by index values ​​relative to 100 of Comparative Example 1 using the reciprocals of the measured values. The higher the index value, the better the braking performance on dry road surfaces. The results are also presented in Tables 1 and 2. [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 TW (mm) 166 180 180 180 180 190 SW (mm) 206 206 206 206 206 215 TW / SW 0,81 0,87 0,87 0,87 0,87 0,88 CW100 (mm) 160 170 170 170 170 176 CW70 (mm) 150 160 160 160 160 154 CW100 / CW70 1,07 1,06 1,06 1,06 1,06 1,14 SH (mm) 121,8 121,8 121,8 121,8 124,8 124,8 SWH (mm) 59 59 59 59 59 59 TW × 0.04 - (SWH / SH - 0.5) × 15 6,9 7,4 7,4 7,4 7,6 8,0 TW × 0.07 - (SWH / SH - 0.5) × 15 11,9 12,8 12,8 12,8 13,0 13,7 D (mm) 6 8 8 8 8 10 R1 (mm) 35 25 25 25 25 15 BW (mm) 160 155 155 155 155 155 BW / TW 0,96 0,86 0,86 0,86 0,86 0,82 Presence / absence of a belt cover No Yes Yes Yes Yes Yes TW × 1 / 4 (mm) 41,5 45 45 45 45 47,5 GC (mm) 46 46 42 42 42 42 L (mm) 30 35 35 42 42 42 L / (TW / 2) 0,36 0,39 0,39 0,47 0,47 0,47 Standard mean tire outer diameter (mm) 652 652 652 652 652 652 Tire outer diameter (mm) 650 650 650 650 656 656 Standard mean total tire width (mm) 209 209 209 209 209 209 Total tire width (mm) 206 206 206 206 206 215 F1 (mm) 60 60 60 60 60 60 F1 / SH 0,49 0,49 0,49 0,49 0,48 0,48 ES (mm) 5 5 5 5 5 5 GD (mm) 8 8 8 8 8 8 Rolling resistance 100 100 100 101 103 103 Dry braking performance 101 102 102,5 102,5 102,5 104 [Table 2] Example 7 Example 8 Example 9 Comparison example 1 Comparison example 2 Comparison example 3 TW (mm) 190 190 190 160 166 158 SW (mm) 215 215 215 206 206 206 TW / SW 0,88 0,88 0,88 0,78 0,81 0,77 CW100 (mm) 176 176 176 154 159 153 CW70 (mm) 154 154 154 150 155 147 CW100 / CW70 1,14 1,14 1,14 1,03 1,03 1,04 SH (mm) 124,8 124,8 124,8 122 122 122 SWH (mm) 59 59 59 59 59 59 TW × 0.04 - (SWH / SH - 0.5) × 15 8,0 8,0 8,0 6,6 6,9 6,6 TW × 0.07 - (SWH / SH - 0.5) × 15 13,7 13,7 13,7 11,4 11,9 11,3 D (mm) 10 10 10 6 6 6 R1 (mm) 15 15 15 35 35 35 BW (mm) 155 155 155 155 160 155 BW / TW 0,82 0,82 0,82 0,97 0,96 0,98 Presence / absence of a belt cover Yes Yes Yes No No No TW × 1 / 4 (mm) 47,5 47,5 47,5 40 41,5 39,5 GC (mm) 42 42 42 46 46 40 L (mm) 42 42 42 30 32 30 L / (TW / 2) 0,44 0,44 0,44 0,38 0,39 0,38 Standard mean tire outer diameter (mm) 652 652 652 652 652 652 Tire outer diameter (mm) 656 656 656 650 650 650 Standard mean total tire width (mm) 209 209 209 209 209 209 Total tire width (mm) 215 215 215 206 206 206 F1 (mm) 80 80 80 60 60 60 F1 / SH 0,64 0,64 0,64 0,49 0,49 0,49 ES (mm) 5 10 10 5 5 5 GD (mm) 8 7 7 8 8 8 Rolling resistance 104 105 106 100 95 101 Dry braking performance 104 104 104,5 100 101 98

[0071] It is apparent from Table 1 that the pneumatic tires of Examples 1 to 9 belonging to the technical scope of the present invention (that is, improvements are added to TW / SW and CW100 / CW70) are superior in both rolling resistance and dry braking performance compared to the pneumatic tires of Comparative Examples 1 to 3 not belonging to the technical scope of the present invention. List of reference symbols 10 pneumatic tires 12 bead section 14 Side wall section 16 Tread section 18 shoulder section 22 Carcass 24 belts 24a, 24b, 24c Belt layer 26 Tread rubber TW tread width SW tire overall width SH tire section height SWH Height in tire radial direction up to the position with maximum tire width

Claims

[1] Pneumatic tire (10), comprising: a pair of left and right bead portions (12); sidewall portions (14) connected to an outer side in the radial direction of the bead portions (12); a tread portion (16) extending between the sidewall portions (14); a carcass (22) including at least one carcass ply extending in a torus shape between the pair of left and right bead portions (12); a belt (24) including at least one belt layer (24a, 24b, 24c) arranged on an outer side in a tire radial direction of the carcass (22) and including cords; and a tread rubber (26) disposed on an outer side in the tire radial direction of the belt (24) and constituting a portion of the tread portion (16), in a state where the pneumatic tire (10) is mounted on a normal rim and inflated to 5% of a predetermined internal pressure, when a tread width is TW and a tire total width is SW in a tire meridian cross-sectional view, a relationship of 0.80 ≤ TW / SW ≤ 0.95 is satisfied, and when a ground contact width at a load of 100% of a maximum load capacity is CW100 and a ground contact width at a load of 70% of the maximum load capacity is CW70, a relationship of 1.04 ≤ CW100 / CW70 ≤ 1.15 is satisfied. [2] A pneumatic tire (10) according to claim 1, wherein when a tire radial direction dimension between an outermost point (P1) in the tire radial direction of an equatorial plane (CL) of the tire (10) and an end point (P2) in the tire width direction of the tread rubber is D, a tire section height is SH, a tire radial direction height up to a tire maximum width position is SWH, and a radius of curvature of an arc of the shoulder portion (18) is R1, a relationship of TW × 0.04 - (SWH / SH - 0.5) × 15 ≤ D ≤ TW × 0.07 - (SWH / SH - 0.5) × 15 and a relationship of 5 mm ≤ R1 ≤ 30 mm are satisfied, and a ratio BW / TW of a width BW of an effective belt layer (24c) and the tread width TW satisfy a relationship of 0.80 ≤ BW / TW ≤ 0.90 and a belt cover (28) is formed on an outer side in the tire width direction of a belt layer (24a) having a maximum width. [3] The pneumatic tire (10) according to claim 1 or 2, wherein the tread portion (16) includes at least two main grooves (32a, 32b) extending in a tire circumferential direction, and a center position (P3) in the tire width direction of the main groove (32b) is present on an outermost side in the tire width direction of the main grooves (32a, 32b) at a position at a distance of 1 / 4 or less of the tread width TW from the equatorial plane (CL) of the tire (10). [4] The pneumatic tire (10) according to any one of claims 1 to 3, wherein an outer contour (42) of the tread portion (16) includes a center portion arc (42a) located at a center portion in the tire width direction and a pair of shoulder arcs (42b) connected to the outer side in the tire width direction of the center portion arc (42a), and when a length in the tire width direction of the center portion arc (42a) is 2L, a relationship of 0.40 ≤ L / (TW / 2) ≤ 0.70 is satisfied. [5] A pneumatic tire (10) according to any one of claims 1 to 4, wherein a tire outer diameter is equal to or larger than a standard average value. [6] A pneumatic tire (10) according to any one of claims 1 to 5, wherein the overall tire width (SW) is equal to or greater than a standard mean value. [7] The pneumatic tire (10) according to any one of claims 1 to 6, wherein the bead portion (12) includes a bead core (12a) and a bead filler (12b) formed on a tire radial direction outer side of the bead core (12a), and when a tire radial direction dimension from a belt edge (P4) to a bead filler top (P5) is F1, a relationship of 0.50 ≤ F1 / SH ≤ 0.80 is satisfied. [8] The pneumatic tire (10) according to any one of claims 1 to 6, wherein the bead portion (10) includes a bead core (12a) and a rubber layer formed on an outer side in the tire radial direction of the bead core (12a), and when a tire radial direction dimension from a belt edge (P4) to a bead core (12a) is F2, a relationship of 0.50 ≤ F2 / SH ≤ 0.80 is satisfied. [9] A pneumatic tire (10) according to any one of claims 1 to 8, wherein a belt edge distance ES between a belt layer (24a) having a maximum width and a belt layer (24c) having a minimum width satisfies a relationship of 5 mm < ES < 15 mm. [10] A pneumatic tire (10) according to any one of claims 1 to 9, wherein when a depth of at least one main groove (32a, 32b) including the equatorial plane (CL) of the tire (10), or a main groove (32a, 32b) closest to the equatorial plane (CL) of the tire (10) among the main grooves (32a, 32b) is GD, a relationship of 4.5 mm ≤ GD ≤ 7.5 mm is satisfied.

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