Tire, tire manufacturing method, and tire design method

Abstract

To provide a tire capable of improving high speed durability while suppressing an increase in rolling resistance.SOLUTION: A tire band 20 is composed of a center part 74 and a pair of side parts 72. A center part 74 is composed of a body 76 and a pair of boundaries 78 positioned between the body 76 and a side part 72. Winding tension Ts of a band strip 48 in the side part 72 is higher than winding tension Tc of the band strip 48 in the body 76. In an axial direction, ends 42a, 42b of the band 20 are positioned outside a grounding reference position. Width Wc of the center part 74 is the same as width CW of a ground plane. Of the band 20, a part protruding outside in the axial direction from the ground reference position is composed of the side part 72.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] The band provided between the tread and the belt includes a band cord extending substantially in the circumferential direction. As this band, a full band that restrains the entire belt and an edge band that restrains the end of the belt or the full band are known. The band suppresses expansion during high-speed running.

[0003] A band strip including a band cord is used to form the band. The band is formed by spirally winding the band strip on a belt formed on a cylindrical drum. The band strip is wound while applying tension. Patent Document 1 below discloses a tire in which the tension of the winding of the band strip is controlled on the tread surface that comes into contact with the road surface, in other words, on the contact surface of the tire with the road surface, in order to improve durability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-1432 A Summary of the Invention [Problem to be solved by the invention]

[0005] A tire with a full band and a pair of edge bands can improve high-speed durability compared to a tire with only a full band. However, the contour of the contact area of ​​this tire tends to be rounded, which promotes heat generation in the shoulder area. There is a concern that the rolling resistance of this tire will increase.

[0006] The drum body used to form the band is usually configured with a flat profile. By configuring the profile of this drum body with a curved surface like the profile of the tread surface, it is possible to improve high-speed durability. However, even in this case, the outline of the contact surface tends to be rounded, and there is a concern that the rolling resistance will increase.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a tire, a tire manufacturing method, and a tire design method that can improve high-speed durability while suppressing an increase in rolling resistance. [Means for solving the problem]

[0008] A tire according to one aspect of the present invention includes a tread that comes into contact with a road surface, a band that is located inside the tread in the radial direction and is formed by spirally winding a band strip including a plurality of parallel band cords, and a belt that is located inside the band in the radial direction. The band includes a center portion and a pair of side portions that are located outside the center portion in the axial direction, and the center portion includes a main body and a pair of boundary portions that are located between the main body and the side portions. The tension Ts of the winding of the band strip in the side portions is higher than the tension Tc of the winding of the band strip in the main body. The tire is mounted on a regular rim, the internal pressure of the tire is adjusted to the regular internal pressure, and the camber angle of the tire is set to 0°. The position on the outer surface of the tread that corresponds to the edge of the contact surface is the contact reference position, which is obtained by applying a vertical load of 80% of the regular load to the tire and contacting the tire with a flat road surface. In the axial direction, the end of the band is located outside the contact reference position. The width of the center portion is the same as the width of the ground contact surface, and the portion of the band that protrudes axially outward from the ground contact reference position comprises the side portion.

[0009] Preferably, in the tire, a ratio of a tension Tc of the winding of the band strip in the main body to a tension Ts of the winding of the band strip in the side portion is equal to or greater than 0.05 and is equal to or less than 0.90.

[0010] Preferably, in the tire, a tension Ts of the winding of the band strip in the side portion is equal to or greater than 40N and equal to or less than 150N.

[0011] Preferably, in the tire, a ratio of a width of the side portion to a width of the center portion is equal to or greater than 2.5% and is equal to or less than 20.0%.

[0012] Preferably, in the tire, the band comprises a full band covering the entire belt.

[0013] Preferably, in the tire, an end of the belt is located, in the axial direction, between a boundary between the center portion and the side portion and an end of the band.

[0014] Preferably, in the tire, a winding tension Tb of the band strip at the boundary portion decreases stepwise from the side portion side toward the main body side.

[0015] Preferably, the tire has a speed rating of V or higher in the JATMA standard.

[0016] A method for manufacturing a tire according to one aspect of the present invention is a method for manufacturing a tire having a tread that comes into contact with a road surface, a band positioned radially inward of the tread, and a belt positioned radially inward of the band. This manufacturing method includes the steps of: (1) providing a green tire for the tire; and (2) A process for vulcanizing the raw tire In the preparation process of the raw tire, the band is formed by spirally winding a band strip including a plurality of parallel band cords while applying tension to the band strip. The band comprises a center portion and a pair of side portions located outside the center portion in the axial direction, and the center portion comprises a main body and a pair of boundary portions located between the main body and the side portions. The tension Ts of the winding of the band strip around the side portions is higher than the tension Tc of the winding of the band strip around the main body. The center portion has the same width as the width of the contact patch obtained by mounting the tire on a regular rim, adjusting the internal pressure of the tire to the regular internal pressure, and contacting the tire with a flat road surface while applying a vertical load of 80% of the regular load with the tire in a state where the camber angle of the tire is set to 0°.

[0017] A tire design method according to one embodiment of the present invention is a method for designing a tire comprising: a tread that comes into contact with a road surface; a band located radially inside the tread and formed by spirally winding a band strip including a plurality of parallel band cords; and a belt located radially inside the band, the band comprising a center portion and a pair of side portions located axially outside the center portion, the center portion comprising a main body and a pair of boundary portions located between the main body and the side portions, and a winding tension Ts of the band strip around the side portions being higher than a winding tension Tc of the band strip around the main body. This design method comprises the steps of: (1) mounting the tire on a standard rim, adjusting the internal pressure of the tire to the standard internal pressure, and applying a vertical load of 80% of the standard load to the tire with the tire in contact with a flat road surface with the tire at a camber angle of 0° to obtain a width of the contact patch; (2) applying the width of the contact surface to the width of the center portion to determine the boundary position between the center portion and the side portion; Includes. Effect of the Invention

[0018] According to the present invention, a tire can be obtained that achieves improved high-speed durability while suppressing an increase in rolling resistance. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a tire according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a band strip. [Diagram 3] FIG. 3 is a side view showing an example of a molding machine used to form the band. [Figure 4] FIG. 4 is an explanatory diagram for explaining a method for forming the band. [Diagram 5] FIG. 5 is an explanatory diagram for explaining an example of a tension profile when the band strip is wound. [Figure 6] FIG. 6 is an image diagram showing the contact surface of a tire. [Figure 7] FIG. 7 is an explanatory diagram illustrating another example of the tension profile of the winding of the band strip. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

[0021] In this disclosure, a state in which a tire is mounted on a standard rim, the internal pressure of the tire is adjusted to a standard internal pressure, and no load is applied to the tire is referred to as a standard state. In the present invention, unless otherwise specified, the dimensions and angles of each part of the tire are measured in the standard state.

[0022] Genuine rims are rims that are specified in the standards on which the tires are based. "Standard rims" in the JATMA standard, "Design Rim" in the TRA standard, and "Measuring Rim" in the ETRTO standard are genuine rims.

[0023] Normal internal pressure means the internal pressure specified in the standard on which the tire is based. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are normal internal pressures. If the tire is for passenger cars, the normal internal pressure is 180kPa unless otherwise specified.

[0024] The normal load means the load specified in the standard on which the tire is based. The "maximum load capacity" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are normal loads. If the tire is for passenger cars, the normal load is a load equivalent to 88% of the above load, unless otherwise specified.

[0025] In the present disclosure, the winding tension of the band strip is expressed as the load (N) per one band cord included in the band strip.

[0026] FIG. 1 shows an example of a tire 2 according to an embodiment of the present invention. This tire 2 is mounted on a passenger vehicle. In FIG. 1, the tire 2 is mounted on a rim R. This rim R is a regular rim. Air is filled inside the tire 2, and the internal pressure of the tire 2 is adjusted to a regular internal pressure. This tire 2 is in a regular condition. The tire 2 mounted on the rim R is also called a tire-rim complex. The tire-rim complex includes the rim R and the tire 2 mounted on the rim R.

[0027] Fig. 1 shows a part of a cross section of the tire 2 taken along a plane including the rotation axis of the tire 2. In Fig. 1, the left-right direction is the axial direction of the tire 2, and the up-down direction is the radial direction of the tire 2. The direction perpendicular to the plane of Fig. 1 is the circumferential direction of the tire 2. In Fig. 1, a dashed dotted line CL represents the equatorial plane of the tire 2.

[0028] The tire 2 includes a tread 4 , a pair of sidewalls 6 , a pair of clinches 8 , a pair of beads 10 , a carcass 12 , a belt 14 , a pair of chafers 16 , an inner liner 18 , and a band 20 .

[0029] The tread 4 is made of a crosslinked rubber in consideration of wear resistance and grip performance. The tread 4 comes into contact with the road surface at its outer surface 22 (also called the tread surface). The tread 4 has grooves 24 formed therein.

[0030] 1, the position indicated by the symbol TE represents a position on the outer surface 22 of the tread 4 that corresponds to the end of the contact patch with the road surface, specifically, the axially outer end of the contact patch. In the tire 2, the position TE is also referred to as the contact reference position.

[0031] The contact patch (also referred to as the reference contact patch) for identifying the contact reference position TE is obtained, for example, by using a contact patch shape measuring device (not shown). This reference contact patch is obtained by mounting the tire 2 on the rim R, adjusting the internal pressure of the tire 2 to the normal internal pressure, and placing the tire 2 in contact with a flat road surface while applying a vertical load of 80% of the normal load with the tire 2 at a camber angle of 0°.

[0032] Each sidewall 6 is continuous with an end of the tread 4. The sidewall 6 is located radially inward of the tread 4. The sidewall 6 extends from the end of the tread 4 toward the clinch 8. The sidewall 6 is made of crosslinked rubber in consideration of cut resistance.

[0033] Each clinch 8 is located radially inward of the sidewall 6. The clinch 8 contacts the rim R. The clinch 8 is made of crosslinked rubber in consideration of wear resistance.

[0034] Each bead 10 is located axially inside the clinch 8. The bead 10 includes a core 26 and an apex 28. The core 26 includes a steel wire. The apex 28 is located radially outside the core 26. The apex 28 is made of crosslinked rubber having high rigidity.

[0035] The carcass 12 is located on the inside of the tread 4, the pair of sidewalls 6, and the pair of clinches 8. The carcass 12 bridges between one bead 10 and the other bead 10. This carcass 12 has a radial structure.

[0036] The carcass 12 includes at least one carcass ply 30. The carcass 12 of the tire 2 is made of one carcass ply 30. The carcass ply 30 is folded back around each of the cores 26.

[0037] Although not shown, the carcass ply 30 includes a number of carcass cords arranged in parallel. These carcass cords are covered with a topping rubber. Each carcass cord crosses the equator plane. The carcass cord is a cord made of an organic fiber. Examples of the organic fiber include nylon fiber, rayon fiber, polyester fiber, and aramid fiber.

[0038] The belt 14 is located radially inside the band 20. The belt 14 is laminated on the carcass 12 on the inside of the tread 4.

[0039] The belt 14 is composed of at least two layers 32 laminated in the radial direction. The belt 14 of the tire 2 is composed of two layers 32 laminated in the radial direction. Of the two layers 32, the layer 32 located on the inside is an inner layer 34, and the layer 32 located on the outside is an outer layer 36. As shown in FIG. 1, the inner layer 34 has a width wider than that of the outer layer 36. In the axial direction, an end 38 of the inner layer 34 is located outside an end 40 of the outer layer 36.

[0040] Although not shown, each of the inner layer 34 and the outer layer 36 includes a number of belt cords arranged in parallel. These belt cords are covered with a topping rubber. Each belt cord is inclined with respect to the equator plane. The material of the belt cord is steel.

[0041] Each chafer 16 is located radially inside the bead 10. The chafer 16 contacts the rim R. In the tire 2, the chafer 16 is made of a cloth and rubber impregnated into the cloth.

[0042] The inner liner 18 is positioned inside the carcass 12. The inner liner 18 constitutes the inner surface of the tire 2. The inner liner 18 is made of a crosslinked rubber having a low gas permeability coefficient. The inner liner 18 maintains the internal pressure of the tire 2.

[0043] The band 20 is located radially inside the tread 4. The band 20 is located radially outside the belt 14 and is laminated on the belt 14. As shown in Fig. 1, an end 42 of the band 20 is located axially outside the end 38 of the inner layer 34, i.e., an end 44 of the belt 14. The band 20 is a full band 46 that covers the entire belt 14. The band 20 of the tire 2 is composed of the full band 46.

[0044] The band 20 includes a band cord. A cord made of an organic fiber is used as the band cord. Examples of the organic fiber include nylon fiber, rayon fiber, polyester fiber, and aramid fiber. The band cord is covered with a topping rubber.

[0045] Although not shown, the band cord extends substantially in the circumferential direction. Specifically, the angle that the band cord forms with the circumferential direction is 5° or less, preferably 2° or less. The band 20 has a jointless structure.

[0046] Next, a method for manufacturing the tire 2 will be described. In manufacturing the tire 2, the tread 4, the beads 10, the carcass 12, the belt 14, etc. are combined to prepare the tire 2 in an unvulcanized state, that is, the green tire for the tire 2 shown in Fig. 1. The manufacturing method for the tire 2 includes a step of preparing a green tire.

[0047] In the manufacture of this tire 2, the band 20 is formed in the preparation process of the raw tire. Since the steps other than the formation of this band 20 are performed in the same manner as in the conventional preparation process, a description thereof will be omitted.

[0048] In manufacturing the tire 2, a band strip 48 shown in Fig. 2 is used to form the band 20. The band strip 48 includes a plurality of band cords 50 arranged in parallel, and these band cords 50 are covered with a topping rubber 52. The band strip 48 is belt-shaped. The band cords 50 included in the band strip 48 extend in the longitudinal direction of the band strip 48.

[0049] 2 includes four band cords 50. The number of band cords 50 included in this band strip 48 is not limited to four. The number of band cords 50 included in the band strip 48 is determined as appropriate in the range of 2 to 15, taking into consideration the specifications of the tire 2, etc.

[0050] 3 shows an example of a molding machine 54. This molding machine 54 is a typical molding machine for forming the band 20. This molding machine 54 includes a drum 56, a reel 58, a delivery roller 60, a guide 62, and a winding roller 64.

[0051] In this forming machine 54, the band strip 48 wound around the reel 58 is supplied to the drum 56. A feed roller 60 feeds the band strip 48 wound around the reel 58 towards the drum 56. A guide 62 guides the band strip 48 to a winding position. A winding roller 64 presses the band strip 48 against the drum 56. This forming machine 54 can spirally wind the band strip 48 around a body portion 66 of the drum 56 by rotating the drum 56 and moving the winding position in the axial direction.

[0052] In the forming machine 54, the band strip 48 is wound while applying tension to the band strip 48. The forming machine 54 includes a tension controller 68 for controlling the tension of the winding of the band strip 48. The tension controller 68 controls the tension of the winding of the band strip 48.

[0053] In the manufacture of the tire 2, the band strip 48 is wound spirally while applying tension to the band strip 48 to form the band 20. There is no particular limitation on the configuration of the tension controller 68 as long as the tension of the winding of the band strip 48 can be controlled. In the manufacture of the tire 2, the tension controller 68 adjusts the rotation speed of the drum 56 and the rotation speed of the delivery roller 60 to control the tension of the winding of the band strip 48.

[0054] In this molding machine 54, the band strip 48 is wound around a body portion 66 of a drum 56. The outer peripheral surface of this body portion 66 is a molding surface 70. In this molding machine 54, the profile of the molding surface 70 is represented by a straight line in a cross section along a plane including the rotation axis of the drum 56. This molding surface 70 has a flat profile in the axial direction.

[0055] Although not described in detail, the drum 56 of the molding machine 54 is used to form the belt 14 and the tread 4 in addition to the band 20. In the manufacture of the tire 2, in a preparation step, the belt 14, the band 20, and the tread 4 are combined on the drum 56 to prepare a tread ring. This preparation step includes a molding step of the tread ring.

[0056] In the tread ring molding process, the belt 14 is formed. In forming the belt 14, an inner sheet for the inner layer 34 and an outer sheet for the outer layer 36 are prepared as preforms of the inner layer 34 and the outer layer 36, which are components of the belt 14. The inner sheet and the outer sheet are wound around the body 66 of the drum 56 in order and processed into a ring shape. As a result, the belt 14 consisting of the inner layer 34 and the outer layer 36 is formed as shown in FIG. 4(a).

[0057] When the belt 14 is formed, the band 20 is formed. In forming the band 20, the band strip 48 is supplied to the drum 56. The drum 56 is rotated, and the winding position of the band strip 48 is moved from one end 44a side of the belt 14 to the other end 44b side. As a result, as shown in FIG. 4(b), the band strip 48 is wound spirally from one end 44a side of the belt 14 to the other end 44b side. As shown in FIG. 4(c), the band 20 is formed on the belt 14. In manufacturing the tire 2, the band 20 is formed by winding one band strip 48 spirally. The band 20 may be formed by using two band strips 48. In this case, the band 20 is formed by winding each band strip 48 spirally from the equatorial plane toward the end 44 of the belt 14, or the band 20 is formed by winding each band strip 48 spirally from the end 44 of the belt 14 toward the equatorial plane.

[0058] As described above, the band cord 50 included in the band 20 of the tire 2 extends substantially in the circumferential direction. The band 20 is formed by the band strip 48 including the band cord 50. The band strip 48 constituting the band 20 also extends substantially in the circumferential direction. The angle that the band strip 48 forms with respect to the circumferential direction is 5° or less, preferably 2° or less.

[0059] When the band 20 is formed, the tread 4 is formed. Although not shown, in forming the tread 4, a tread sheet, which is a preform of the tread 4, is prepared. The tread sheet is wound around the band 20 formed on the body 66 of the drum 56 and processed into a ring shape. In this way, the tread 4 is formed. Alternatively, a tread strip processed into a band shape may be prepared as the preform of the tread 4, and the tread 4 may be wound around the band 20 to form the tread 4.

[0060] Although not described in detail, in the manufacture of this tire 2, a green tire base is prepared by combining elements such as an inner liner 18, a pair of chafers 16, a carcass 12, a pair of beads 10, etc. in a separate molding machine 54. A green tire is obtained by combining the above-mentioned tread ring with this green tire base. A green tire may be prepared by forming a belt 14, a band 20, and a tread 4 in this order on the green tire base.

[0061] In the manufacture of this tire 2, the green tire prepared in the preparation step is placed in a mold (not shown). The green tire is pressurized and heated in the mold. This causes the green tire to be vulcanized, and the tire 2 shown in FIG. 1 is obtained. The manufacturing method of this tire 2 includes a step of vulcanizing the green tire. In the manufacture of this tire 2, the vulcanization step is performed in the same manner as a conventional vulcanization step, and therefore a description thereof will be omitted.

[0062] In the tire 2, the band 20 is formed by spirally winding the band strip 48. Since the molding machine 54 can change the winding tension of the band strip 48 in the middle of forming the band 20, the band 20 can have a plurality of parts with different winding tensions of the band strip 48. Below, the winding tension profile of the band strip 48 of the tire 2 will be described with reference to FIG. 5.

[0063] Fig. 5(a) is a graph conceptually showing the relationship between the winding tension of the band strip 48 and the position of each part of the band 20. The vertical axis represents the magnitude of the tension, and the horizontal axis represents the distance from one end 42a of the band 20. Fig. 5(b) is a schematic diagram showing the band 20 corresponding to the tension profile shown in Fig. 5(a) together with the belt 14. Fig. 5(c) is an image of the reference contact surface of the tire 2.

[0064] In Fig. 5, the left-right direction corresponds to the axial direction of the tire 2. In Fig. 5, the left-right length in Fig. 5(a), the left-right length in Fig. 5(b), and the left-right length in Fig. 5(c) are expressed on the same scale.

[0065] 5, the symbol SE denotes the axial outer end of the reference ground contact surface, in other words, the ground contact end of the reference ground contact surface. The position on the outer surface of the tread 4 corresponding to this ground contact end SE is the above-mentioned ground contact reference position TE.

[0066] In FIG. 5, the double arrow CW is the width of the reference ground plane. This width CW is represented by the axial distance from one ground edge SE to the other ground edge SE. This width CW is identified in the image of this reference ground plane. This width CW is equal to the axial distance from one ground reference position TE to the other ground reference position TE measured along the tread surface.

[0067] In FIG. 5, the double arrow SW is the width of the outer layer 36. The width SW of the outer layer 36 is represented by the axial distance from one end 40a to the other end 40b of the outer layer 36, measured along the outer surface of the outer layer 36. The double arrow UW is the width of the inner layer 34. The width UW of the inner layer 34 is represented by the axial distance from one end 38a to the other end 38b of the inner layer 34, measured along the outer surface of the inner layer 34. The double arrow BW is the width of the band 20. The width BW of the band 20 is represented by the axial distance from one end 42a to the other end 42b of the band 20, measured along the molding surface 70 of the drum 56. The width SW of the outer layer 36, the width UW of the inner layer 34, and the width BW of the band 20 may be specified in the tire 2. In this case, the width BW of the band 20 is measured along the outer surface of the carcass 12.

[0068] The tension profile of the winding of the band strip 48 will be described below using as an example the case where the band strip 48 is wound spirally from one end 42a to the other end 42b of the band 20.

[0069] In a first zone from position P1 to position P2 corresponding to one end 42a of the band 20, the tension T (hereinafter, tension T) of the band strip 48 is maintained at tension Ts. In a second zone from position P2 to position P3, the tension T is lowered from tension Ts to tension Tc. In a third zone from position P3 to position P4, the tension T is maintained at tension Tc. In a fourth zone from position P4 to position P5, the tension T is increased from tension Tc to tension Ts. And in a fifth zone from position P5 to position P6 corresponding to the other end 42b of the band 20, the tension T is maintained at tension Ts.

[0070] In the tire 2, the portion corresponding to the first zone where the tension T is maintained at tension Ts and the portion corresponding to the fifth zone are the side portions 72 of the band 20. The portion located between the side portions 72 and corresponding to the portion consisting of the second zone, the third zone, and the fourth zone is the center portion 74 of the band 20. In the center portion 74, the portion corresponding to the third zone where the tension T is maintained at tension Tc lower than tension Ts is the main body 76 of the center portion 74, and the portion located between the main body 76 and the side portions 72 and corresponding to the second zone where the tension T is changed between tension Ts and tension Tc and the portion corresponding to the fourth zone is the boundary portion 78 of the center portion 74.

[0071] In the tire 2, the band 20 is composed of a center portion 74 and a pair of side portions 72 located outside the center portion 74 in the axial direction. The center portion 74 is composed of a main body 76 and a pair of boundary portions 78 located between the main body 76 and the side portions 72. The tension Ts of the winding of the band strip 48 around the side portions 72 is higher than the tension Tc of the winding of the band strip 48 around the main body 76 of the center portion 74.

[0072] In the tire 2, the tension Tb of the band strip 48 around the boundary portion 78 on the one end 42a side of the band 20 drops from tension Ts to tension Tc in a single go. The tension Tb of the band strip 48 around the boundary portion 78 on the other end 42b side rises from tension Tc to tension Ts in a single go. The tension Tb of the band strip 48 around the boundary portion 78 is changed from tension Ts to tension Tc or from tension Tc to tension Ts until the band strip 48 is wound one turn.

[0073] As described above, the tension Ts of the winding of the band strip 48 around the side portion 72 is higher than the tension Tb of the winding of the band strip 48 around the main body 76. The tension Ts of the winding of the band strip 48 around the side portion 72 is higher than the tension Tb of the winding of the band strip 48 around the boundary portion 78. In the tire 2, the tension T of the winding of the band strip 48 is high in the side portion 72 and low in the center portion 74.

[0074] In FIG. 5, the double-headed arrow Wc indicates the width of the center portion 74, and the double-headed arrow Ws indicates the width of the side portion 72. The widths Wc and Ws are specified in a tread ring formed on the body portion 66 of the drum 56 in the green tire preparation process. The width Wc of the center portion 74 is represented by the axial distance from position P2 to position P5 measured along the molding surface 70 of the drum 56. The width Ws of one side portion 72 is represented by the axial distance from position P1 to position P2 measured along the molding surface 70 of the drum 56. The width Ws of the other side portion 72 is represented by the axial distance from position P5 to position P6 measured along the molding surface 70 of the drum 56. In FIG. 5, the symbol PB indicates the boundary between the center portion 74 and the side portion 72. This boundary PB is both the inner end of the side portion 72 and the outer end of the center portion 74. In addition, when the boundary PB can be specified by the edge of the band strip 48, the width Wc and the width Ws may be measured in the tire 2. In this case, a position on the outer surface of the carcass 12 corresponding to the boundary PB is specified on a normal line of the outer surface of the carcass 12 that passes through the boundary PB, and the width Wc and the width Ws are measured along the outer surface of the carcass 12.

[0075] In this tire 2, the band 20 is formed so that the center portion 74 has the same width as the width CW of the reference ground contact surface. In other words, the width Wc of the center portion 74 is the same as the width CW of the reference ground contact surface. Here, the width Wc of the center portion 74 being the same as the width CW of the reference ground contact surface means that the ratio (Wc / CW) of the width Wc to the width CW is 0.98 or more and 1.02 or less.

[0076] As shown in FIG. 1, in the tire 2, the end 42 of the band 20 is located outside the ground contact reference position TE in the axial direction. In other words, the band 20 is configured such that a portion thereof protrudes axially outward from the ground contact reference position TE. In the tire 2, the portion of the band 20 protruding axially outward from the ground contact reference position TE is made up of the side portion 72. As described above, the tension Ts of the winding of the band strip 48 around the side portion 72 is high. The side portion 72 sufficiently restrains the shoulder portion Sh. In the tire 2, the high-speed durability is improved.

[0077] In this tire 2, in order to improve high-speed durability, for example, there is no need to provide the edge band 20. This band 20 contributes to reducing the number of parts.

[0078] Figure 6 shows an image of the reference contact surface of the tire 2. The image of this reference contact surface is the same as the image of the reference contact surface shown in Figure 5(c). In Figure 6, the up-down direction corresponds to the circumferential direction of the tire 2, and the left-right direction corresponds to the axial direction of the tire 2. The direction perpendicular to the paper surface corresponds to the radial direction of the tire 2.

[0079] In Fig. 6, the dashed dotted line LP is a straight line corresponding to the equatorial plane of the tire 2 on the reference contact surface. When it is difficult to identify the equatorial plane on the reference contact surface, the axial center line of the reference contact surface is used as the straight line corresponding to the equatorial plane. The double-headed arrow P100 is the length of the intersection line between a plane including the line LP and the reference contact surface. In this tire 2, the length P100 of this intersection line is the equatorial contact length measured along the equatorial plane on the reference contact surface.

[0080] In FIG. 6, the solid line LM is a straight line that passes through the ground edge SE of the reference ground surface and is parallel to the straight line LP. The solid line L80 is a straight line that is located between the straight lines LM and LP and is parallel to the straight lines LM and LP. The double-headed arrow A100 represents the axial distance from the straight line LP to the straight line LM. This distance A100 corresponds to the maximum width of the reference ground surface, i.e., half of the maximum ground contact width. The double-headed arrow A80 represents the axial distance from the straight line LP to the straight line L80. In FIG. 6, the ratio of the distance A80 to the distance A100 is set to 80%. That is, the straight line L80 represents a position that corresponds to 80% of the maximum ground contact width of the reference ground surface. The double-headed arrow P80 is the length of the intersection line between the plane including the straight line L80 and the reference ground surface. In this tire 2, the length P80 of this intersection line is the reference ground contact length at a position on the reference ground surface that corresponds to 80% of the maximum ground contact width.

[0081] In this tire 2, by specifying the equatorial contact length P100 and the reference contact length P80 in the reference contact patch shown in Fig. 6, a shape index F expressed as the ratio (P100 / P80) of the equatorial contact length P100 to the reference contact length P80 is obtained. A larger value of this shape index F indicates that the reference contact patch has a rounder contour.

[0082] If the contact patch is rounded, the deformation amount of the shoulder portion Sh increases, and there is a concern that the rolling resistance increases. The inventors have intensively studied the correlation between the shape index F and the rolling resistance, and have found that if the shape index F of the reference contact patch is less than 1.38, the increase in rolling resistance can be suppressed, and that controlling the tension of the winding of the band strip 48 in consideration of the width CW of the reference contact patch is effective for controlling the contour of the reference contact patch. These findings are applied to the tire 2.

[0083] As described above, in this tire 2, the width Wc of the center portion 74 is the same as the width CW of the reference contact surface, and the band 20 is configured so that the winding tension Ts of the band strip 48 in the side portion 72 located axially outboard of this center portion 74 is higher than the winding tension Tc of the band strip 48 in the main body 76 of the center portion 74. As a result, a shape index F of 1.37 or less is achieved in this tire 2. In this tire 2, the contour of the contact surface is prevented from becoming rounded, in other words, the rounding of the contact surface is suppressed.

[0084] In this tire 2, rounding of the contact patch is suppressed even though the shoulder portion Sh is sufficiently restrained by the band 20. Since heat generation accompanying deformation of the shoulder portion Sh is suppressed, an increase in rolling resistance is suppressed in this tire 2. This tire 2 can improve high-speed durability while suppressing an increase in rolling resistance.

[0085] The contour of the reference contact patch also affects the wear resistance of tire 2. In tire 2, the shape index F is 1.30 or more. In tire 2, good wear resistance is maintained.

[0086] In the tire 2, the ratio (Tc / Ts) of the winding tension Tc of the band strip 48 in the main body 76 of the center portion 74 to the winding tension Ts of the band strip 48 in the side portion 72 is preferably 0.05 or more and 0.90 or less.

[0087] By setting the ratio (Tc / Ts) to be equal to or greater than 0.05, the side portion 72 sufficiently restrains the shoulder portion Sh. This improves the high-speed durability of the tire 2. From this viewpoint, the ratio (Tc / Ts) is more preferably equal to or greater than 0.13, further preferably equal to or greater than 0.17, and particularly preferably equal to or greater than 0.25.

[0088] By setting the ratio (Tc / Ts) to be equal to or less than 0.90, the band 20 effectively suppresses rounding of the contact patch. An increase in rolling resistance is suppressed in the tire 2. From this viewpoint, the ratio (Tc / Ts) is more preferably equal to or less than 0.75, further preferably equal to or less than 0.50, and particularly preferably equal to or less than 0.40.

[0089] In the tire 2, the tension Ts of the band strip 48 wrapped around the side portion 72 is preferably 40N or more and 150N or less.

[0090] By setting the tension Ts to 40 N or greater, the side portion 72 sufficiently restrains the shoulder portion Sh. This improves high-speed durability in the tire 2. From this viewpoint, the tension Ts is more preferably 50 N or greater, and further preferably 60 N or greater.

[0091] By setting the tension Ts to 150 N or less, the band 20 effectively suppresses rounding of the contact surface. An increase in rolling resistance is suppressed in the tire 2. From this viewpoint, the tension Ts is more preferably 100 N or less, and further preferably 80 N or less.

[0092] In the tire 2, from the viewpoint of improving high-speed durability while suppressing an increase in rolling resistance, the ratio (Ws / Wc) of the width Ws of the side portion 72 to the width Wc of the center portion 74 is preferably 2.5% or more, more preferably 5.0% or more, and even more preferably 7.5% or more. This ratio (Ws / Wc) is preferably 20.0% or less, more preferably 15.0% or less, and even more preferably 10.0% or less.

[0093] 1, in the tire 2, the end 44 of the belt 14 is located between the boundary PB between the center portion 74 and the side portion 72 and the end 42 of the band 20 in the axial direction. In the tire 2, the belt 14 also effectively contributes to the rigidity control of the tread 4, so that the band 20 can more effectively restrain the shoulder portion Sh and more effectively suppress rounding of the contact patch. From this viewpoint, in the tire 2, it is preferable that the end 44 of the belt 14 is located between the boundary PB between the center portion 74 and the side portion 72 and the end 42 of the band 20 in the axial direction.

[0094] In this tire 2, from the viewpoint of allowing the belt 14 to more effectively contribute to improving high-speed durability while suppressing an increase in rolling resistance, it is more preferable that, in the axial direction, the end 40 of the outer layer 36 forming a part of the belt 14 is located outside the boundary PB, the end 38 of the inner layer 34 forming another part of the belt 14 is located outside the end 40 of the outer layer 36, and the end 42 of the band 20 is located outside the end 38 of the inner layer 34. In other words, it is more preferable that the width SW of the outer layer 36 is wider than the width CW of the reference ground contact surface, the width UW of the inner layer 34 is wider than the width SW of the outer layer 36, and the width BW of the band 20 is wider than the width UW of the inner layer 34.

[0095] In this tire 2, from the viewpoint of improving high-speed durability while suppressing an increase in rolling resistance, the ratio (SW / CW) of the width SW of the outer layer 36 to the width CW of the reference contact surface is preferably 1.01 or more and preferably 1.03 or less. From the same viewpoint, the ratio (UW / SW) of the width UW of the inner layer 34 to the width SW of the outer layer 36 is preferably 1.06 or more and preferably 1.10 or less. From the same viewpoint, the ratio (BW / UW) of the width BW of the band 20 to the width UW of the inner layer 34 is preferably 1.03 or more and preferably 1.07 or less.

[0096] FIG. 7 shows another example of the tension profile of the winding of the band strip 48. FIG. 7(a) is a graph conceptually showing the relationship between the tension of the winding of the band strip 48 and the position of each part of the band 20. The vertical axis represents the magnitude of the tension, and the horizontal axis represents the distance from one end 42a of the band 20. FIG. 7(b) is a schematic diagram showing the band 20 corresponding to the tension profile shown in FIG. 7(a) together with the belt 14. FIG. 7(c) is an image of the reference ground contact surface of the tire 2. Since the contents are the same as those shown in FIG. 5 except for the tension profile of the winding of the band strip 48 and the image of the reference ground contact surface, the description thereof will be omitted.

[0097] 7(a), in the tension profile of the winding of the band strip 48, in the first zone from position P1 to position P2 corresponding to one end 42a of the band 20, the tension T is maintained at tension Ts. In the second zone from position P2 to position P3, the tension T is lowered from tension Ts to tension Tc. In the third zone from position P3 to position P4, the tension T is maintained at tension Tc. In the fourth zone from position P4 to position P5, the tension T is increased from tension Tc to tension Tc. And in the fifth zone from position P5 to position P6 corresponding to the other end 42b of the band 20, the tension T is maintained at tension Ts.

[0098] 7(a), the portion corresponding to the first zone where the tension T is maintained at tension Ts and the portion corresponding to the fifth zone are side portions 72. The portion located between the side portions 72 and corresponding to the portion consisting of the second zone, third zone, and fourth zone is a center portion 74. In the center portion 74, the portion corresponding to the third zone where the tension T is maintained at tension Tc lower than tension Ts is a main body 76 of the center portion 74, and the portion located between the main body 76 and the side portions 72 and corresponding to the second zone where the tension T is changed between tension Ts and tension Tc and the portion corresponding to the fourth zone is a boundary portion 78 of the center portion 74.

[0099] This band 20 also consists of a center portion 74 and a pair of side portions 72 located outside the center portion 74 in the axial direction. The center portion 74 consists of a main body 76 and a pair of boundary portions 78 located between the main body 76 and the side portions 72. The tension Ts of the winding of the band strip 48 around the side portions 72 is higher than the tension Tc of the winding of the band strip 48 around the main body 76 of the center portion 74.

[0100] In this band 20, the tension Tb of the band strip 48 around the boundary portion 78 on the one end 42a side is gradually decreased from tension Ts to tension Tc. The tension Tb of the band strip 48 around the boundary portion 78 on the other end 42b side is gradually increased from tension Tc to tension Ts. In other words, in this band 20, the tension of the band strip 48 around the boundary portion 78 is gradually decreased from the side portion 72 side toward the main body 76 side.

[0101] Even if the winding tension Tb of the band strip 48 at the boundary portion 78 is reduced stepwise, rather than all at once, from the side portion 72 side toward the main body 76 side, in the tire 2, the end 42 of the band 20 is located outside the ground contact reference position TE in the axial direction, and the portion of the band 20 protruding axially outward from the ground contact reference position TE consists of the side portion 72. Since the winding tension Ts of the band strip 48 at the side portion 72 is high, this side portion 72 sufficiently restrains the shoulder portion Sh. In this tire 2, the high-speed durability is improved.

[0102] Even if the tension of the band strip 48 around the boundary 78 is gradually reduced from the side 72 toward the main body 76, the width Wc of the center 74 is the same as the width CW of the reference ground contact surface, and the tension Ts of the band strip 48 around the side 72 located axially outside the center 74 is higher than the tension Tb of the band strip 48 around the boundary 78. As described above, the tension Ts of the band strip 48 around the side 72 is higher than the tension Tc of the band strip 48 around the main body 76. Since the tension T of the band strip 48 around the side 72 is higher than the tension Tc of the band strip 48 around the main body 76, the band 20 also contributes to suppressing the rounding of the ground contact surface. Since the heat generation caused by the deformation of the shoulder portion Sh is suppressed, the increase in rolling resistance is suppressed.

[0103] In this way, even when the tension T of the band strip 48 is configured with the tension profile shown in Fig. 7(a), the increase in rolling resistance is suppressed and high-speed durability is improved. In this case, the tension Tb is gradually reduced while the band strip 48 is wound, and the number of turns of the band strip 48 wound in the process of changing the tension Tb from tension Ts to tension Tc or from tension Tc to tension Ts is preferably 7 times or less, more preferably 5 times or less, and even more preferably 3 times or less. From the viewpoint of effectively improving high-speed durability while sufficiently suppressing the increase in rolling resistance, the tension profile shown in Fig. 5(a) is particularly preferable as the tension profile of the band strip 48 wound in the tire 2.

[0104] The tire 2 described above is designed as follows. The design method of this tire 2 is a method for designing a tire 2 including a tread 4 that comes into contact with the road surface, a band 20 located on the inside of the tread 4 in the radial direction and formed by spirally winding a band strip 48 including a plurality of parallel band cords 50, and a belt 14 located on the inside of the band 20 in the radial direction, the band 20 comprising a center portion 74 and a pair of side portions 72 located on the outside of the center portion 74 in the axial direction, the center portion 74 comprising a main body 76 and a pair of boundary portions 78 located between the main body 76 and the side portions 72, and the winding tension Ts of the band strip 48 around the side portions 72 is higher than the winding tension Tc of the band strip 48 around the main body 76. This design method is as follows: (1) A step of mounting the tire 2 on a standard rim (rim R), adjusting the internal pressure of the tire 2 to the standard internal pressure, and placing the tire 2 in contact with a flat road surface while applying a vertical load of 80% of the standard load to the tire 2 with the tire 2 at a camber angle of 0°, thereby confirming the width CW of the contact surface, i.e., the reference contact surface; (2) A step of applying the width CW of the reference ground plane to the width Wc of the center portion 74 to determine the position of the boundary PB between the center portion 74 and the side portion 72. By applying this design method to the above-mentioned manufacturing method, a tire 2 is obtained having a band 20 in which the center portion 74 has the same width Wc as the width CW of the reference ground contact surface, and the winding tension T of the band strip 48 is high in the side portion 72 and low in the center portion 74. This band 20 sufficiently restrains the shoulder portion Sh and effectively suppresses rounding of the ground contact surface. This tire 2 can improve high-speed durability while suppressing an increase in rolling resistance.

[0105] As described above, according to the present invention, it is possible to obtain a tire 2, a manufacturing method for the tire 2, and a design method for the tire 2, which are capable of improving high-speed durability while suppressing an increase in rolling resistance. The present invention is particularly effective for a tire 2 having a speed rating of V or higher according to the JATMA standard. EXAMPLES

[0106] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0107] [Example 1] A pneumatic tire for passenger cars (tire size=225 / 45R17 91V) having the basic structure shown in FIG. 1 and the specifications shown in Table 1 below was obtained.

[0108] In this Example 1, the width CW of the reference ground plane was 179 mm. The ratio (Wc / CW) of the width Wc of the center portion to the width CW of the reference ground plane was set to 1.01. The width Wc of the center portion was substantially the same as the width CW of the reference ground plane. The ratio (Ws / Wc) of the width Ws of the side portion to the width Wc of the center portion was 7.5%.

[0109] The tension Ts of the band strip around the side portion was set to 60 N, and the tension Tc of the band strip around the body in the center portion was set to 20 N. Therefore, the ratio of the tension Tc to the tension Ts (Tc / Ts) was 0.33.

[0110] In this Example 1, the ratio of the outer layer width SW to the reference ground plane width CW (SW / CW) was set to 1.02, and the ratio of the inner layer width UW to the outer layer width SW (UW / SW) was set to 1.08.

[0111] [Comparative Example 1] A tire of Comparative Example 1 was obtained in the same manner as in Example 1, except that the winding tension of the band strip was set to 20 N to form the entire band, and the ratio (BW / CW) of the width BW of the band to the width CW of the reference ground contact surface was set to 1.01. This Comparative Example 1 is a conventional tire.

[0112] [Comparative Example 2] A tire of Comparative Example 2 was obtained in the same manner as in Example 1, except that the tension Tc and the tension Ts were changed to make the ratio (Tc / Ts) as shown in Table 1 below.

[0113] [Comparative Example 3] A tire of Comparative Example 3 was obtained in the same manner as in Example 1, except that the winding tension of the band strip was set to 60 N to form the entire band, and the ratio (BW / CW) of the width BW of the band to the width CW of the reference contact surface was set to 1.15.

[0114] [Comparative Example 4] A tire of Comparative Example 4 was obtained in the same manner as in Example 1, except that the ratio (Wc / CW) was set as shown in the following Table 1. In this Comparative Example 4, the band was configured so that the width Wc of the center portion was narrower than the width CW of the reference contact patch.

[0115] [Comparative Example 5] A tire of Comparative Example 5 was obtained in the same manner as in Example 1, except that the ratio (Wc / CW) was as shown in Table 1 below. In this Comparative Example 5, the band was configured so that the width Wc of the center portion was wider than the width CW of the reference ground contact surface. In this Comparative Example 5, the center portion was included in the portion of the band that protruded axially outward from the ground contact reference position TE.

[0116] [Example 2-5] Tires of Examples 2 to 5 were obtained in the same manner as in Example 1, except that the tension Tc and the tension Ts were changed to make the ratio (Tc / Ts) as shown in Table 2 below.

[0117] [Examples 6-7] The tires of Examples 6-7 were obtained in the same manner as Example 1, except that the tensions Tc and Ts were changed so that the ratio (Tc / Ts) was as shown in Tables 2 and 3 below, and the ratio (Ws / Wc) was as shown in Tables 2 and 3.

[0118] [Examples 8-11] Tires of Examples 8 to 11 were obtained in the same manner as in Example 1, except that the ratio (Ws / Wc) was set as shown in Table 3 below.

[0119] [Rolling resistance coefficient (RRC)] Using a rolling resistance tester, the rolling resistance coefficient (RRC) was measured when the prototype tire was running on a drum at a speed of 80 km / h under the following conditions. The results are shown in Table 1-3 below as an index based on Comparative Example 1. The smaller the value, the smaller the rolling resistance. In this evaluation, an index of 0.3 or less is acceptable as it is considered that the increase in rolling resistance is suppressed. Rim: 7.5J Internal pressure: 250kPa Vertical load: 5.26kN

[0120] [High speed durability (H / S)] Using a drum tester, high-speed durability was evaluated by the step speed method under the following conditions. In this evaluation, the running speed was increased stepwise, and the speed and time at which the tire broke were measured. The speed at which Comparative Example 1 broke was set as the reference step, and the number of steps changed from this reference step is shown in Table 1-3 below. The larger the value, the better the high-speed durability. If the breakage time at the breakage step was more than half the set time for that step, 0.5 steps were added. Rim: 7.5J Internal pressure: 250kPa Vertical load: 5.26kN Camber angle: 3° Temperature: 25℃

[0121] [Table 1]

[0122] [Table 2]

[0123] [Table 3]

[0124] As shown in Table 1-3, in the examples, improvement in high-speed durability was achieved while suppressing an increase in rolling resistance. From these evaluation results, the superiority of the present invention is clear. [Industrial Applicability]

[0125] The above-described technology for improving high-speed durability while suppressing an increase in rolling resistance can be applied to various types of tires. [Explanation of symbols]

[0126] 2. Tires 4. Tread 12. Carcass 14. Belt 20. Band 22...Outer surface of tread 4 34...inner layer 36...outer layer 46...Full Band 48···Band strip 50···Band cord 54...Molding machine 56 Drums 60... Feed roller 66 - Body of drum 56 68...Tension controller 70...molding surface 72 Side section 74 Center section 76...Main unit 78...Border

Claims

1. A tread that comes into contact with the road surface; A band is positioned radially inside the tread and is formed by spirally winding a band strip including a plurality of band cords arranged in parallel; A belt located radially inside the band; Equipped with The band includes a center portion and a pair of side portions located outside the center portion in the axial direction, the center portion comprises a main body and a pair of boundary portions located between the main body and the side portions, A tension Ts of the band strip around the side portion is higher than a tension Tc of the band strip around the main body, a tension Tb of the band strip around the boundary portion is lower than a tension Ts of the band strip around the side portion and higher than a tension Tc of the band strip around the main body; The tire is mounted on a regular rim, the internal pressure is adjusted to the regular internal pressure, the camber angle is set to 0°, and a vertical load of 80% of the regular load is applied to the tire when the tire is brought into contact with a flat road surface. The position on the outer surface of the tread that corresponds to the edge of the contact patch is the contact reference position. an end of the band is located outside the ground reference position in the axial direction; a ratio of the width of the center portion to the width of the ground contact surface is 0.98 or more and 1.02 or less; The tension Ts of the band strip around the side portion is 50 N or more and 150 N or less, A tire in which a portion of the band protruding axially outward from the ground contact reference position constitutes the side portion.

2. The tire according to claim 1, wherein a ratio of a tension Tc of the winding of the band strip in the main body to a tension Ts of the winding of the band strip in the side portion is equal to or greater than 0.05 and is equal to or less than 0.

90.

3. The tire according to claim 1 or 2, wherein a ratio of a width of the side portion to a width of the center portion is 2.5% or more and 20.0% or less.

4. The tire according to claim 1 , wherein the band is a full band that covers the entire belt.

5. The tire according to claim 1 , wherein an end of the belt is located axially between a boundary between the center portion and the side portion and an end of the band.

6. The tire according to claim 1 , wherein a tension Tb of the winding of the band strip at the boundary portion decreases stepwise from the side portion side toward the main body side.

7. The tire according to claim 1 , having a speed rating of V or higher according to the JATMA standard.

8. 1. A method for manufacturing a tire having a tread in contact with a road surface, a band radially inward of the tread, and a belt radially inward of the band, comprising the steps of: providing a green tire for the tire; vulcanizing the raw tire; Including, In the raw tire preparation step, The band strip including the plurality of parallel band cords is wound spirally while applying tension to the band strip to form the band; The band includes a center portion and a pair of side portions located outside the center portion in the axial direction, the center portion comprises a main body and a pair of boundary portions located between the main body and the side portions, A tension Ts of the band strip around the side portion is higher than a tension Tc of the band strip around the main body, a tension Tb of the band strip around the boundary portion is lower than a tension Ts of the band strip around the side portion and higher than a tension Tc of the band strip around the main body; The tension Ts of the band strip around the side portion is 50 N or more and 150 N or less, a tire manufacturing method in which the tire is mounted on a normal rim, the internal pressure of the tire is adjusted to a normal internal pressure, and the camber angle of the tire is set to 0° while a vertical load of 80% of a normal load is applied to the tire and the tire is brought into contact with a flat road surface, so that the ratio of the width of the center portion to the width of the contact patch is 0.98 or more and 1.02 or less.

9. A method for designing a tire comprising: a tread that comes into contact with a road surface; a band located radially inside the tread and formed by spirally winding a band strip including a plurality of parallel band cords; and a belt located radially inside the band, wherein the band comprises a center portion and a pair of side portions located outside the center portion in the axial direction, the center portion comprises a main body and a pair of boundary portions located between the main body and the side portions, a winding tension Ts of the band strip around the side portions is higher than a winding tension Tc of the band strip around the main body, and a winding tension Tb of the band strip around the boundary portions is lower than a winding tension Ts of the band strip around the side portions and higher than a winding tension Tc of the band strip around the main body, a step of mounting the tire on a standard rim, adjusting the internal pressure of the tire to a standard internal pressure, and applying a vertical load of 80% of a standard load to the tire with a camber angle of 0° and bringing the tire into contact with a flat road surface to obtain a width of the contact patch; applying the width of the ground contact surface to the width of the center portion to determine a boundary position between the center portion and the side portion; Including, The tension Ts of the band strip around the side portion is 50 N or more and 150 N or less, A method for designing a tire, wherein a ratio of a width of the center portion to a width of the contact patch is 0.98 or greater and 1.02 or less.

Images