Tire, tire manufacturing method and vehicle

Abstract

To provide a tire that achieves reduced rolling resistance of the tire for increased fuel efficiency, a method for producing a tire and a vehicle.SOLUTION: A tire is attached to a prescribed rim and receives prescribed internal pressure. At no load, the relationship between the outer diameter OD and the total width SW of the tire satisfies following formula(1): OD≤-0.0019×SW2+1.4×SW+400.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tire, a tire manufacturing method, and a vehicle. [Background technology]

[0002] A known technology for reducing the rolling resistance of a tire and improving fuel efficiency is the technology disclosed in Patent Document 1. In Patent Document 1, the rolling resistance of a tire is reduced by defining the relationship between the tire cross-sectional width and the bead diameter, and by defining the belt cord angle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-33984 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology disclosed in Patent Document 1 leaves room for improvement in terms of reducing the rolling resistance of tires and improving fuel efficiency.

[0005] The present invention has been made in view of the above, and an object of the present invention is to provide a tire, a tire manufacturing method, and a vehicle that can improve fuel efficiency performance. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, a tire according to an embodiment of the present invention is a tire that is mounted on a specified rim, has a specified internal pressure, and is in an unloaded state, and has a relationship between a tire outer diameter OD and a total width SW that satisfies the following formula (1): When the length SWD is twice the radial length from the tire rotation axis to the measurement position of the total width SW, the total strength T [kg] of the carcass satisfies the following formula (2). It's a tire. OD≦-0.0019×SW 2 +1.4×SW+400 …(1) T≧α×[(OD / 2) 2 -(SWD / 2) 2 ] …(2) However, in equation (2), the constant α is 0.224.

[0008] It is preferable that the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (3). OD≦-0.0024×SW 2 +1.6×SW+362 …(3)

[0009] When the total width SW is 150 mm or less, it is preferable that the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (4). OD≦-0.0060×SW 2 +5.9×SW-183 …(4) In another aspect of the present invention, a tire is mounted on a specified rim, a specified internal pressure is applied, and the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (1) when the tire is in an unloaded state: When the total width SW is 150 mm or less, the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (4). OD≦-0.0019×SW 2 +1.4×SW+400 …(1) OD≦-0.0060×SW 2 +5.9×SW-183 …(4)

[0010] In the above formula (2), the constant α is preferably 0.448.

[0011] It is preferable that the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (5). OD≧-0.0017×SW 2 +0.9×SW+350 …(5)

[0012] It is preferable that the maximum load capacity W [kgf] satisfies the following formula (6). W≧β×10 -4 ×Sd 1.39 ×(D-12.7+Sd) …(6) However, in formula (6), The constant β is 7.1, The value Sd=0.93×SW−0.637×d, Value d = (0.9 - aspect ratio) x SW - 6.35, The value D = inner diameter x 25.4.

[0013] It is preferable that the maximum load capacity when an internal pressure of 250 kPa is applied is a value exceeding the load capacity defined by the nominal value, aspect ratio and inner diameter of the JATMA standard for automobile tires.

[0014] It is preferable that the maximum load capacity when an internal pressure of 250 kPa is applied be 102% or more and 400% or less of the load capacity defined by the nominal value, aspect ratio and inner diameter of the JATMA standard for automobile tires.

[0015] It is preferable that the maximum allowable air pressure is set to be higher than 180 [kPa], the value set by the JATMA standard for automobile tires, and equal to or lower than 1200 [kPa].

[0016] It is preferable that the maximum speed used is 120km / h or less.

[0017] The tire outer diameter OD is preferably 480 mm or more.

[0018] In order to solve the above problems and achieve the object, a method for manufacturing a tire according to one aspect of the present invention comprises the steps of: A manufacturing method for a tire, in which the relationship between the tire outer diameter OD and total width SW satisfies the following formula (1) when the tire is mounted on a specified rim and a specified internal pressure is applied, and in an unloaded state, the total strength T [kg] of the carcass satisfies the following formula (2) when the length SWD is twice the length in the tire radial direction from the tire rotation axis to a measurement position of the total width SW, A tire manufacturing method including: a first step of designing a molding die so that the relationship between the tire outer diameter OD and total width SW satisfies the following formula (1); a second step of determining a carcass to be used for a tire to be molded using the molding die designed in the first step so that the total strength T [kg] of the following formula (2) is satisfied; a third step of molding a primary green tire; a fourth step of molding a belt and tread assembly; a fifth step of bonding the primary green tire obtained in the third step and the belt and tread assembly obtained in the fourth step to mold a secondary green tire; and a sixth step of vulcanizing and molding the secondary green tire obtained in the fifth step. OD≦-0.0019×SW 2 +1.4×SW+400 …(1) T≧α×[(OD / 2)2 -(SWD / 2) 2 ] …(2) However, in equation (2), the constant α is 0.224.

[0019] In order to solve the above problems and achieve the object, a vehicle according to an embodiment of the present invention includes any one of the above tires and has at least one motor as a power source. In addition, the vehicle preferably includes five or more of any one of the above tires. Effect of the Invention

[0020] The tire, tire manufacturing method, and vehicle of the present invention can improve fuel efficiency. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a meridian cross-sectional view showing an example of a tire according to the present embodiment. [Diagram 2] FIG. 2 is an enlarged view of a portion of FIG. [Diagram 3] FIG. 3 is a flowchart showing the tire manufacturing method according to this embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a shaping process. [Diagram 5] FIG. 5 is a diagram showing an example of tire arrangement on a vehicle. [Figure 6] FIG. 6 is a diagram showing an example of tire arrangement on a vehicle. [Figure 7] FIG. 7 is a diagram showing an example of tire arrangement on a vehicle. [Figure 8] FIG. 8 is a diagram showing an example of tire arrangement on a vehicle. [Figure 9] FIG. 9 is a diagram showing an example of tire arrangement on a vehicle. [Figure 10] FIG. 10 is a diagram showing an example of tire arrangement on a vehicle. [Figure 11] FIG. 11 is a diagram showing an example of tire arrangement on a vehicle. [Figure 12] FIG. 12 is a diagram showing an example of tire arrangement on a vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In the following description of each embodiment, the same or equivalent components as those in other embodiments are given the same reference numerals, and their description will be simplified or omitted. The present invention is not limited to each embodiment. In addition, the components of each embodiment include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same. The configurations described below can be appropriately combined. In addition, the configurations can be omitted, replaced, or modified within the scope of the gist of the invention.

[0023] (tire) FIG. 1 is a meridian cross-sectional view showing an example of a tire 1 according to the present embodiment. FIG. 2 is an enlarged view of a part of FIG. 1. In the following description, the meridian cross-section of the tire refers to a cross-section of the tire cut by a plane including the rotation axis AX of the tire. The tire radial direction refers to a direction perpendicular to the rotation axis AX of the tire 1, the tire radial inner side refers to a side facing the rotation axis AX in the tire radial direction, and the tire radial outer side refers to a side away from the rotation axis AX in the tire radial direction. The tire circumferential direction refers to a direction around the rotation axis AX as a central axis. The tire width direction refers to a direction parallel to the rotation axis AX, the tire width inner side refers to a side facing the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the tire width outer side refers to a side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane perpendicular to the rotation axis AX of the tire 1 and passing through the center of the tire width of the tire 1. The tire width is the width in the tire width direction between the portions located on the outer sides in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line refers to a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the tire 1. In this embodiment, the tire equatorial line is given the same symbol "CL" as the tire equatorial plane.

[0024] The tire 1 according to the present embodiment is preferably a pneumatic tire. As the gas to be filled into the tire 1, in addition to normal air or air with an adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium can be used.

[0025] The tire 1 according to this embodiment has an annular structure centered on a rotation axis AX and is rotatable about the rotation axis AX. The tire 1 has a tread portion 2, shoulder portions 3 on both sides of the tread portion 2, and sidewall portions 4 and bead portions 5 successively continuing from each shoulder portion 3. The tire 1 also includes a carcass layer 6, a belt layer 7, a belt reinforcing layer 8, and an inner liner 9.

[0026] The tread portion 2 is formed in an annular shape extending in the tire circumferential direction at the outermost part in the tire radial direction when viewed in a tire meridian section, and is exposed at the outermost part in the tire radial direction of the tire 1, with its outer peripheral surface forming the contour of the tire 1. The outer peripheral surface of the tread portion 2 is formed as a contact surface 10 that is a surface that may come into contact with the road surface mainly during running, and the contact surface 10 has a plurality of grooves formed therein, such as circumferential grooves 16 extending in the tire circumferential direction and lug grooves (not shown) extending in the tire width direction. The tread portion 2 also has a tread rubber 18 that is a rubber composition. The tread rubber 18 may be formed by laminating a plurality of rubber compositions having different physical properties in the tire radial direction.

[0027] The shoulder portions 3 are the portions on both outer sides of the tread portion 2 in the tire width direction. The sidewall portions 4 are located on the inner side of the shoulder portions 3 in the tire radial direction, and a pair of sidewall portions 4 are disposed on both sides in the tire width direction. That is, the pair of sidewall portions 4 are disposed on both sides of the tread portion 2 in the tire width direction, in other words, the sidewall portions 4 are disposed at two locations on both sides of the tire 1 in the tire width direction. The sidewall portions 4 thus formed are curved in a direction that convex outward in the tire width direction when viewed in a tire meridian cross section, and are the portions of the tire 1 that are exposed on the outermost sides in the tire width direction.

[0028] The bead portions 5 are disposed on the radially inner side of each of the pair of sidewall portions 4, and like the sidewall portions 4, a pair are disposed on both sides of the tire equatorial plane CL in the tire width direction. Each bead portion 5 has a bead core 11 and a bead filler 12. The bead core 11 is formed by winding a bead wire, which is a steel wire, into a ring shape. The bead filler 12 is a rubber material disposed in a space formed by folding back the tire width direction end portion of the carcass layer 6 at the position of the bead core 11.

[0029] The sidewall portion 4 and the bead portion 5 are included in a tire side portion 20 located on both sides in the tire width direction. In this embodiment, the tire side portion 20 refers to a region between a position on the inner side in the tire radial direction of the tread rubber 18 and a bead heel 14 which is an end portion on the outer side in the tire width direction of the inner circumferential surface of the bead portion 5.

[0030] Moreover, the total width SW of the tire 1 refers to the linear distance between the sides of the tire 1 when the tire 1 is mounted on a specified rim, inflated to a specified air pressure, and in an unloaded state, including all patterns or letters on the side of the tire 1. In other words, the total width of the tire 1 refers to the distance in the tire width direction between the outermost portion of the structure constituting the tire 1 located on one side of the tire equatorial plane CL and the outermost portion of the structure constituting the tire 1 located on the other side. Note that the distance SWD is twice the distance from the rotation axis AX to the measurement position of the total width SW.

[0031] Here, the specified rim is the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure is the "maximum air pressure" specified by JATMA, the maximum value listed in the "tire load limits at various cold inflation pressures" specified by TRA, or the "inflation pressures" specified by ETRTO. For example, the specified internal pressure is 250 kPa.

[0032] The carcass layer 6 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies stacked together. The carcass layer 6 is toroidally stretched between the left and right bead cores 11, 11 to form the framework of the tire 1. In addition, both ends of the carcass layer 6 are wound back and secured to the outside in the tire width direction so as to envelop the bead cores 11 and the bead fillers 12. In addition, the carcass ply of the carcass layer 6 is formed by covering multiple carcass cords made of steel or organic fiber material with coating rubber and rolling them, and has a cord angle of 80 degrees or more and 100 degrees or less. The cord angle is defined as the inclination angle of the longitudinal direction of the carcass cord with respect to the tire circumferential direction.

[0033] The belt layer 7 has a multi-layer structure in which at least two layers of belts 7a, 7b are laminated. The belt layer 7 is disposed on the outer periphery of the carcass layer 6 in the tread portion 2 in the radial direction of the tire. The belt layer 7 covers the carcass layer 6 in the circumferential direction of the tire. The belts 7a, 7b have a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20° to 30°) with respect to the circumferential direction of the tire. The cords are covered with a coating rubber. The cords are made of, for example, steel or organic fibers such as polyester, rayon, or nylon. The overlapping belts 7a, 7b are disposed so that the cords cross each other.

[0034] The belt reinforcing layer 8 is disposed on the outer side in the tire radial direction, which is the outer periphery of the belt layer 7, and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is formed by covering a plurality of cords (not shown) arranged in parallel in the tire circumferential direction and in the tire width direction with a coating rubber. The cords are made of, for example, steel or organic fibers such as polyester, rayon, or nylon, and the angle of the cords is within a range of ±5° with respect to the tire circumferential direction. In this embodiment, the belt reinforcing layer 8 is formed by laminating two layers: a belt cover 8a arranged so as to cover the entire belt layer 7 in the tire width direction, and an edge cover 8b arranged only near the tire width direction end of the belt layer 7 on the tire radial outer side of the belt cover 8a. The belt reinforcing layer 8 may have a configuration other than this, and may be composed of only the belt cover 8a arranged so as to cover the entire belt layer 7, or only the edge cover 8b arranged so as to cover the tire width direction end of the belt layer 7. The belt reinforcing layer 8 may be arranged so as to overlap at least the tire width direction end of the belt layer 7. The belt reinforcing layer 8 thus constructed is disposed by winding a belt-shaped strip material having a width of, for example, about 10 mm in the circumferential direction of the tire.

[0035] The inner liner 9 is disposed along the carcass layer 6 on the inner cavity surface of the tire 1. The inner liner 9 is an air permeation preventing layer that covers the carcass layer 6. The inner liner 9 suppresses oxidation due to exposure of the carcass layer 6, and also prevents leakage of air filled in the tire 1. The inner liner 9 is composed of, for example, a rubber composition mainly composed of butyl rubber, a thermoplastic resin, or a thermoplastic elastomer composition in which an elastomer component is blended into a thermoplastic resin.

[0036] The above-described internal structure of the tire 1 is a representative example of the tire 1, and the internal structure is not limited to this.

[0037] (Relationship between tire outer diameter and total width, total strength of carcass layer) When the tire 1 of the present embodiment is mounted on a specified rim, given a specified internal pressure, and in an unloaded state, it is preferable that the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (1). OD≦-0.0019×SW 2 +1.4×SW+400 …(1)

[0038] A tire 1 that satisfies the relationship of formula (1) can reduce rotational inertia and weight, thereby improving fuel economy. Here, it is possible to narrow the tire and increase its outer diameter in order to improve fuel economy. However, such a tire can reduce rolling resistance, but increases rotational inertia. For this reason, it may not be possible to improve fuel economy. On the other hand, a tire 1 with a small outer diameter has a small rotational inertia and a small tire mass, thereby improving fuel economy.

[0039] In addition, since the tire 1 that satisfies the relationship of formula (1) has a small outer diameter, the vehicle on which the tire 1 is mounted can have a low floor, thereby ensuring space inside the vehicle. Here, the space inside the vehicle refers to the living space and luggage carrying space inside the vehicle.

[0040] Furthermore, in the tire 1 of this embodiment, when the length SWD is twice the radial length from the rotation axis AX to the measurement position of the total width SW, it is preferable that the total strength T [kg] of the carcass layer 6 satisfies the following formula (2). T≧α×[(OD / 2) 2 -(SWD / 2) 2 ] …(2) However, in equation (2), the constant α is 0.224.

[0041] By satisfying formula (2), the total strength of the carcass layer 6, which is the tire framework, can be increased, and the load-bearing capacity of the tire 1 can be ensured even when the load increases. In other words, by making the outer diameter of the tire 1 smaller while setting the total strength T of the carcass layer 6 to a predetermined value or more, it is possible to achieve both a smaller diameter and improved load-bearing capacity.

[0042] The carcass ply of the carcass layer 6 can be selected arbitrarily as long as the total strength satisfies the specified value. In addition to rayon and polyester, high-strength steel, nylon, aramid, hybrids, etc. can be selected. By using high-strength cords, weight reduction is possible, which is more effective. By increasing the strength of the carcass layer 6, it can be used at high internal pressures such as 500 [kPa] and 900 [kPa], and the load capacity can be further increased. The total strength T is calculated by multiplying the strength per cord by the number of cords. The above tire outer diameter OD, total width SW, and length SWD are values ​​measured when the tire 1 is mounted on a specified rim, the specified internal pressure is applied, and no load is applied.

[0043] In addition, in the tire 1 of the present embodiment, when the total width SW is 150 mm or less, it is preferable that the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (3). OD≦-0.0024×SW 2 +1.6×SW+362 …(3)

[0044] The tire 1 that satisfies formula (3) can have a smaller outer diameter, which can further improve fuel efficiency, lower the floor of the vehicle on which it is mounted, and ensure a larger space inside the vehicle.

[0045] Furthermore, in the tire 1 of the present embodiment, when the total width SW is 150 mm or less, it is preferable that the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (4). OD≦-0.0060×SW 2 +5.9×SW-183 …(4)

[0046] If the total width SW is 150 mm or less, the outer diameter will grow larger during inflation, and the contact length will become longer, resulting in increased rolling resistance. By making the diameter smaller, the rolling resistance will decrease and the rolling resistance performance will improve.

[0047] In the above formula (2), the constant α is more preferably 0.448. This can further increase the load capacity and improve the fuel efficiency of the vehicle equipped with the tire 1. The constant α is more preferably 0.672, and further preferably 0.896.

[0048] The tire outer diameter OD is preferably 480 mm or more. If the tire outer diameter OD is too small, the load capacity described below may be insufficient. By making the tire outer diameter OD larger than 480 mm, a large space can be secured inside the vehicle and a high load capacity can be achieved.

[0049] Furthermore, it is preferable that the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (5): If the tire outer diameter OD and the total width SW have such a relationship, fuel efficiency performance can be improved. OD≧-0.0017×SW 2 +0.9×SW+350 …(5)

[0050] (Maximum load capacity) It is preferable that the maximum load capacity W [kgf] of the tire 1 satisfies the following formula (6). W≧β×10 -4 ×Sd 1.39 ×(D-12.7+Sd) …(6)

[0051] In the formula (6), the constant β is 7.1, the value Sd = 0.93 × SW - 0.637 × d [mm], the value d = (0.9 - aspect ratio) × SW - 6.35 [mm], and the value D = inner diameter × 25.4 [mm]. Note that the maximum load capacity W [kgf] is the load index defined by JATMA.

[0052] By increasing the total strength T of the carcass layer 6, the maximum load capacity W can be set in a high range as shown in the above formula (5). The constant β is 9.1, more preferably 10.1, and even more preferably 12.8. By setting the constant β in this way, the effect of reducing transportation costs is further increased.

[0053] Here, the maximum load capacity W when an internal pressure of 250 kPa is applied to the tire 1 may be set to a value exceeding the load capacity defined by the nominal size, aspect ratio, and inner diameter of automobile tire standards (e.g., JATMA). Since the total strength T of the carcass layer 6 is large, the tire 1 can be used in a high load capacity range.

[0054] In addition, it is preferable that the value of the maximum load capacity W when the tire 1 is applied with an internal pressure of 250 [kPa] is set to a value in the range of 102 [%] or more and 400 [%] or less of the load capacity defined by the nominal, aspect ratio, and inner diameter of the standard for automobile tires (for example, JATMA). Since the total strength T of the carcass layer 6 is large, the load capacity can be used at a high value. If the value of the maximum load capacity W is smaller than the above range, the effect of reducing the transportation cost is small, which is not preferable. If the value of the maximum load capacity W is larger than the above range, the deformation of the tire 1 is significantly large, which is not preferable, and the effect of reducing the transportation cost is small. It is more preferable that the value of the maximum load capacity W when the tire 1 is applied with an internal pressure of 250 [kPa] is set to a value in the range of 114% or more and 330% or less of the load capacity defined by the nominal, aspect ratio, and inner diameter of the standard for automobile tires (for example, JATMA).

[0055] (Maximum air pressure) It is preferable that the maximum usable air pressure of the tire 1 is greater than the stipulated value of 180 [kPa] in the standards for automobile tires (for example, JATMA) and is equal to or less than 1200 [kPa]. Since the total strength T of the carcass layer 6 is large, the air pressure applied to the tire 1 can be set in a high range. By increasing the air pressure, the load capacity can be increased, and the effect of reducing transportation costs can be further increased. Increasing the air pressure above the range is undesirable because it creates a risk in the internal pressure filling operation. It is more preferable that the maximum usable air pressure of the tire 1 is equal to or less than 1000 [kPa].

[0056] (maximum speed used) The maximum speed at which the tire 1 is used is preferably 120 km / h or less. The maximum speed at which the tire 1 is used is preferably 100 km / h or less, more preferably 80 km / h or less, and even more preferably 60 km / h or less. The tire 1 can have a larger load capacity when used at low speeds.

[0057] (Tire manufacturing method) Fig. 3 is a flowchart showing a method for manufacturing a tire according to this embodiment. Fig. 3 shows a method for manufacturing the tire 1 shown in Figs. 1 and 2. In the flowchart shown in Fig. 3, first, a molding die is designed (step ST11) so that the relationship between the tire outer diameter OD and the total width SW satisfies formula (1). Designing the molding die is the first step in the method for manufacturing the tire 1. The designed molding die is produced and set in a vulcanizer (not shown).

[0058] Next, a carcass to be used for the tire to be molded using the molding die designed in step ST11 is determined (step ST12). Determining the carcass is the second step in the manufacturing method of tire 1. At this time, the carcass is determined so that the total strength T of the carcass layer 6 satisfies formula (2). The material of the carcass used for the carcass layer 6 is a material suitable for the small tire outer diameter OD and total width SW. For example, a steel carcass is used.

[0059] Next, a primary green tire is molded (step ST13). Molding the primary green tire is the third step in the manufacturing method of the tire 1. When molding the primary green tire, materials for forming each part of the bead member, the carcass layer 6, the sidewall portion 4, and the inner liner 9 are set on a molding drum that is expandable and contractible in the axial direction. The bead member includes a pair of bead cores 11, a pair of bead fillers 12, and a rim cushion rubber. Then, the left and right carcass layers are rolled up to mold a cylindrical primary green tire (step ST13). In other words, the primary green tire does not include the belt layer 7, and is the part that is radially inward of the belt layer 7.

[0060] Next, the belt-tread assembly is molded (step ST14). Molding the belt-tread assembly is the fourth step in the manufacturing method of the tire 1. The belt-tread assembly includes the belt layer 7, a material corresponding to the belt reinforcing layer 8, and a tread rubber corresponding to the tread portion 2. In other words, the belt-tread assembly includes the belt layer 7 and is a portion on the outer side of the belt layer 7 in the tire radial direction.

[0061] Then, shaping is performed (step ST15). Shaping is the fifth step in the manufacturing method of tire 1. Shaping is a process of bonding the primary green tire obtained in step ST13 and the belt-tread assembly obtained in step ST14 together to form a secondary green tire.

[0062] FIG. 4 is a diagram showing an example of a shaping process. In the shaping process of step ST15, a bladder 26 for crimping is used when bonding the primary green tire and the belt-tread assembly. In the shaping process, the primary green tire X and the belt-tread assembly Y are crimped to form a green tire Z having a toroidal shape. More specifically, as shown in FIG. 4A, the primary green tire X is held on the left and right beadlock drums 25, 25, and the belt-tread assembly Y is held from the circumferential outside by a transfer (not shown). Then, as shown in FIG. 4B, while the interval between the left and right beadlock drums 25, 25 is narrowed, the primary green tire X is expanded in diameter by the bladder 26 for crimping and pressed against the belt-tread assembly Y. At this time, the internal pressure of the bladder 26 is set higher to apply pressure, and the interval between the beads is narrowed to form a vertically elongated shape, thereby achieving both a smaller diameter and improved load capacity. In this manner, the primary green tire X and the belt-tread assembly Y are pressed together to form the secondary green tire Z.

[0063] Thereafter, the secondary green tire Z is put into a molding die set in a vulcanizer in step ST11 and vulcanized (step ST16). The vulcanization is the sixth step in the manufacturing method of the tire 1. In the vulcanization, a bladder for vulcanization (not shown) separate from the bladder 26 for pressing is used.

[0064] (vehicle) Here, a vehicle on which the tire 1 is mounted will be described. Figs. 5 to 12 are diagrams showing examples of the arrangement of the tires 1 on the vehicle. The vehicle on which the tires 1 are mounted preferably includes five or more tires 1. The vehicle on which the tires 1 are mounted may have, for example, three axles and include five tires 1. The vehicle on which the tires 1 are mounted may also have, for example, three axles and include six tires 1. Furthermore, since the tire 1 has a small outer diameter, increasing the number of wheels has little effect on the space inside the vehicle. By employing the tire 1, the load capacity can be improved, which greatly reduces transportation costs.

[0065] The number of wheels of the vehicle on which the tire 1 is mounted, i.e., the number of tires 1, is preferably in the range of 6 to 12. Fewer than 5 wheels is not preferred because the load capacity is insufficient. More than 12 wheels is not preferred because the space inside the vehicle becomes narrow.

[0066] Fig. 5 is a side view of a vehicle 100A on which the tire 1 is mounted. Fig. 6 is a tire arrangement diagram of the vehicle 100A shown in Fig. 5. As shown in Figs. 5 and 6, the vehicle 100A has four axles J1 to J4 and eight tires 11 to 18. Tires 11 and 12 are connected to the axle J1. Tires 13 and 14 are connected to the axle J2. Tires 15 and 16 are connected to the axle J3. Tires 17 and 18 are connected to the axle J4.

[0067] The vehicle 100A also has a power unit 101. The power unit 101 provides power to at least one of the axles J1 to J4. The power unit 101 is, for example, an internal combustion engine or a motor that operates using electrical energy. In other words, the vehicle 100A on which the tire 1 is mounted preferably has at least a motor as one of its power sources. When a motor is the power source, reducing the rotational inertia has a significant effect of reducing fuel consumption (power consumption), which also leads to an increase in the life of the motor itself. When the motor output of the tire 1 is reduced, for example with an in-wheel motor, the effect of reducing fuel consumption (power consumption) is extremely large.

[0068] Fig. 7 is a side view of a vehicle 100B on which the tire 1 is mounted. Fig. 8 is a tire arrangement diagram of the vehicle 100B shown in Fig. 7. As shown in Figs. 7 and 8, the vehicle 100B has three axles J1 to J3 and six tires 11 to 16. Tires 11 and 12 are connected to the axle J1. Tires 13 and 14 are connected to the axle J2. Tires 15 and 16 are connected to the axle J3.

[0069] The vehicle 100B also includes a power unit 101. The power unit 101 provides power to at least one of the axles J1 to J3. The power unit 101 is, for example, an internal combustion engine or a motor that operates using electrical energy.

[0070] Fig. 9 is a side view of a vehicle 100C on which the tire 1 is mounted. Fig. 10 is a tire arrangement diagram of the vehicle 100C shown in Fig. 9. As shown in Figs. 9 and 10, the vehicle 100C has three axles J1, J2 and JC and five tires 11 to 15. Tires 11 and 12 are connected to the axle J1. Tires 13 and 14 are connected to the axle J2. Tire 15 is connected to the axle JC.

[0071] The vehicle 100C also includes a power unit 101. The power unit 101 provides power to at least one of the axles J1, J2, and JC. The power unit 101 is, for example, an internal combustion engine or a motor that operates using electrical energy.

[0072] Fig. 11 is a side view of a vehicle 100D on which the tire 1 is mounted. Fig. 12 is a tire arrangement diagram of the vehicle 100D shown in Fig. 11. As shown in Figs. 11 and 12, the vehicle 100D has six axles J1 to J6 and twelve tires 11 to 12. 12 The axle J1 has tires 11 and 12 connected thereto. The axle J2 has tires 13 and 14 connected thereto. The axle J3 has tires 15 and 16 connected thereto. The axle J4 has tires 17 and 18 connected thereto. The axle J5 has tires 19 and 10 connected thereto. 10 Axle J6 has one tire. 11 and 1 12 is connected.

[0073] The vehicle 100D also includes a power unit 101. The power unit 101 provides power to at least one of the axles J1 to J6. The power unit 101 is, for example, an internal combustion engine or a motor that operates using electrical energy.

[0074] The tires 1 on the vehicle may be arranged in a manner other than that shown in Figures 5 to 12. For example, a double tire arrangement in which four tires are mounted on one axle may be used.

[0075] Each of the vehicles 100A to 100D described with reference to Fig. 5 to Fig. 12 may be an autonomous vehicle. An autonomous vehicle is a vehicle that can travel autonomously without human driving.

[0076] (Example) Tables 1 and 2 show the results of performance tests of tire 1 according to the present invention. In these performance tests, different tires were evaluated for fuel economy and maximum load support capacity. In these performance tests, tires of sizes such as 145 / 80R12 were mounted on rims of 12×4.00B. The above-mentioned "145 / 80R12" is an example, and evaluation was performed on tires with different outer diameters and total widths as shown in Tables 1 and 2. The air pressures shown in Tables 1 and 2 were applied.

[0077] To evaluate fuel economy, an evaluation vehicle fitted with test tires was driven 50 times around a 2km test course at 100km / h, and the fuel consumption (km / l) during the test run was measured. Fuel economy was calculated by expressing the reciprocal of the measured fuel consumption as an index, with the conventional example (described below) set as the standard (100). The higher the figure, the lower the fuel consumption and the better the fuel economy.

[0078] The maximum load-bearing capacity is calculated by multiplying the load capacity by the number of wheels fitted. It is shown as an index with the conventional example described below as the standard (100). The higher the index, the higher the load capacity. The total strength of the carcass layer is calculated by multiplying the strength of one cord by the number of cords. The strength of one cord was determined by removing the carcass cord from the sidewall and measuring the breaking strength of the carcass cord in accordance with JIS L1017, and then calculating the strength of the carcass layer from this breaking strength. The breaking strength was calculated as the average value of a total of 30 carcass cords, 10 cords taken from each of three tires.

[0079] In Tables 1 and 2, "◯" indicates that the condition is met, and "×" indicates that the condition is not met.

[0080] In Table 1, the conventional tire has an outer diameter OD of 559 mm, an overall width SW of 139 mm, a length SWD of 421 mm, a value Sd of 124 mm, an aspect ratio of 80, an inner diameter of 12 inches, a value D of 305 mm, and a value d of 8 mm.

[0081] As shown in Tables 1 and 2, the tires of Examples 1 to 12 exhibited better results in terms of fuel economy performance than the conventional tire. Also, as shown in Tables 1 and 2, the tires of Examples 1 to 12 exhibited better results in terms of maximum load support capacity than the conventional tire.

[0082] [Table 1]

[0083] [Table 2] [Explanation of symbols]

[0084] 1, 11~1 12 tire 2 Tread section 3 Shoulder section 4 Sidewall 5 Bead section 6 Carcass layer 7 Belt layer 8 Belt reinforcement layer 9 Inner Liner 10 Ground plane 11 Bead core 12 Bead filler 14 Bead Heel 16 Circumferential groove 18 Tread rubber 20 Tire side 100A~100D Vehicles 101 Power section AX Rotation Axis CL Tire Equatorial Plane J1~J6, JC axle OD Tire outer diameter SW Overall width SWD Distance T Total Strength X Primary Green Tire Y-belt and tread assembly Z Secondary Green Tire Z

Claims

1. When the tire is mounted on a specified rim and has a specified internal pressure, and is in an unloaded state, the relationship between the tire outer diameter (OD) and the total width (SW) satisfies the following formula (1): A tire in which the total strength T [kg] of the carcass satisfies the following formula (2), where SWD is twice the radial length from the tire rotation axis to the measurement position of the total width SW. OD≦-0.0019×SW ２ +1.4×SW+400 …(1) T≧α×[(OD / 2) 2 - (SWD / 2) 2 ] …(2) However, in equation (2), the constant α is 0.

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2. The tire according to claim 1 , wherein the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (3): OD≦-0.0024×SW ２ +1.6×SW+362 …(3)

3. 2. The tire according to claim 1, wherein in said formula (2), the constant α is 0.

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4. 4. The tire according to claim 1, wherein, when the total width SW is 150 mm or less, a relationship between the tire outer diameter OD and the total width SW satisfies the following formula (4): OD≦-0.0060×SW ２ +5.9×SW-183 …(4)

5. When the tire is mounted on a specified rim and has a specified internal pressure, and when the tire is in an unloaded state, the relationship between the tire outer diameter (OD) and the total width (SW) satisfies the following formula (1): A tire in which, when the total width SW is 150 mm or less, a relationship between the tire outer diameter OD and the total width SW satisfies the following formula (4): OD≦-0.0019×SW2+1.4×SW+400 … (1) OD≦-0.0060×SW2+5.9×SW−183 … (4)

6. The tire according to claim 1 , wherein a relationship between the tire outer diameter OD and the total width SW satisfies the following formula (5): OD≧-0.0017×SW ２ +0.9×SW+350 …(5)

7. The tire according to any one of claims 1 to 6, wherein a maximum load capacity W [kgf] satisfies the following formula (6): W≧β×10 －４ ×Sd １．３９ ×(D-12.7+Sd) …(6) However, in the formula (6), The constant β is 7.1, The value Sd=0.93×SW−0.637×d, Value d = (0.9 - aspect ratio) x SW - 6.35, The value D = inner diameter x 25.

4.

8. 7. The tire according to claim 1, wherein the maximum load capacity when an internal pressure of 180 kPa is applied is set to a value exceeding the load capacity defined by the nominal size, aspect ratio and inner diameter of the JATMA standard for automobile tires.

9. 9. The tire according to claim 1, wherein the maximum load capacity when an internal pressure of 180 kPa is applied is 102% or more and 400% or less of the load capacity defined by the nominal, aspect ratio and inner diameter of the JATMA standard for automobile tires.

10. 10. The tire according to claim 1, wherein the maximum allowable air pressure is higher than 180 kPa and equal to or lower than 1200 kPa, the specified value of the JATMA standard for automobile tires.

11. The tire according to any one of claims 1 to 10, wherein the maximum speed at which the tire is used is 120 km / h or less.

12. The tire according to claim 1 , wherein the tire outer diameter OD is equal to or greater than 480 mm.

13. When the tire is mounted on a specified rim and a specified internal pressure is applied, and when no load is applied, the relationship between the tire outer diameter OD and the total width SW satisfies the following formula (1): A method for manufacturing a tire, in which a total strength T [kg] of a carcass satisfies the following formula (2), when a length SWD is twice the length in the tire radial direction from the tire rotation axis to a measurement position of the total width SW, A first step of designing a molding die so that a relationship between a tire outer diameter (OD) and a total width (SW) satisfies the following formula (1); A second step of determining a carcass to be used for a tire to be molded using the molding die designed in the first step so as to satisfy the total strength T [kg] of the following formula (2); a third step of forming a primary green tire; a fourth step of forming the belt-tread assembly; a fifth step of laminating the primary green tire obtained in the third step with the belt-tread assembly obtained in the fourth step to form a secondary green tire; A sixth step of vulcanizing and molding the secondary green tire obtained by the fifth step; A method for manufacturing a tire comprising the steps of: OD≦-0.0019×SW ２ +1.4×SW+400 …(1) T≧α×[(OD / 2) ２ -(SWD / 2) ２ ] …(2) However, in equation (2), the constant α is 0.

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14. A vehicle including the tire according to any one of claims 1 to 12, and using at least a motor as one of its power sources.

15. 13. A vehicle comprising five or more tires according to any one of claims 1 to 12.

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