JP6058294B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention relates to a pneumatic tire for a motorcycle.

  FIG. 9 shows a conventional pneumatic tire 2 for a two-wheeled vehicle. The tire 2 includes a tread 4, a sidewall 6, a wing 8, a bead 10, a carcass 12, an inner liner 14, a chafer 16, and a band 18.

  The band 18 is laminated with the carcass 12 on the radially inner side of the tread 4. The band 18 includes a cord. The cord is wound in a spiral. The band 18 has a jointless structure. The cord extends substantially in the circumferential direction.

  The band 18 of the tire 2 is formed using the ribbon 20 shown in FIG. The ribbon 20 includes three cords 22 and a topping rubber 24. The ribbon 20 is spirally wound on the carcass 12. Thereby, the band 18 is obtained.

  FIG. 11 shows a cross section of the cord 22 included in the band 18. The code 22 includes nine strands 26. The material of each strand 26 is steel. This cord 22 is called a steel cord.

  In the tire 2, the cord 22 of the band 18 is formed by preparing three strands 28 formed by twisting three strands 26 and further twisting these strands 28. The cord 22 has a double twist structure. The configuration of the code 22 is expressed as “3 × 3”.

  The configuration of the cord 22 affects the performance of the tire 2. From this point of view, various studies have been made on the configuration of the code 22. Examples of this study are disclosed in Japanese Patent Laid-Open Nos. 2000-096467 and 2007-056403.

JP 2000-096467 A JP 2007-056403 A

  FIG. 12 shows a cross section of a cord 30 different from the cord 22 shown in FIG. The cord 30 is formed by twisting five strands 32. The cord 30 has a single twist structure. The configuration of the code 30 is represented as “1 × 5”. This cord 30 is lighter than the double twisted cord 22 shown in FIG. From the viewpoint of weight reduction, the cord 30 may be used for the band 18 instead of the double twisted cord 22.

  FIG. 13 shows the state of the tire 2 fitted to the rim 34. In FIG. 13, what is indicated by a two-dot chain line is a state of the tire 2 before being fitted to the rim 34.

  As shown in the drawing, when the tire 2 is mounted on the rim 34, the position of the core 36 of the bead 10 moves inward in the axial direction from the position of the core 36 before mounting. Thereby, the end portion (shoulder) of the tread 4 moves inward in the radial direction. An arrow A in the figure represents this moving direction.

  The cord 30 of the band 18 is wound spirally. In the cross section along the radial direction of the tire 2, the cord 30 forms a ring. For this reason, when the shoulder of the tire 2 moves inward in the radial direction, the diameter of the ring made of the cord 30 on the shoulder is reduced. As a result, a compressive force acts on the cord 30 in the length direction.

  The elongation of the single stranded cord 30 in FIG. 13 is smaller than the elongation of the double stranded cord 22 in FIG. The compression rigidity in the length direction of the single twist cord 30 is larger than the compression rigidity in the length direction of the double twist cord 22. For this reason, when a compressive force acts on the cord 30, the cord 30 may be buckled because the compressive force cannot be buffered.

  The cord 30 of the band 18 extends substantially in the circumferential direction. For this reason, when the cord 30 is buckled, the shoulder of the tire 2 may wave along the circumferential direction. This undulation generates vibrations in the tire 2. This undulation affects the wear resistance and the ground contact feeling of the tire 2. The tire 2 is inferior in handling stability.

  An object of the present invention is to provide a pneumatic tire for a two-wheeled vehicle in which weight reduction is achieved without impairing steering stability.

  The pneumatic tire according to the present invention has a tread whose outer surface forms a tread surface, a pair of sidewalls that extend substantially inward in the radial direction from the end of the tread, and each of which is substantially inward in the radial direction from the sidewall. A pair of beads positioned on the inside of the tread and the side walls along the inside of the side wall, between the one bead and the other bead, and on the radially inner side of the tread, on the radially outer side of the carcass And a band located at. The carcass has a radial structure. The band includes a cord that is spirally wound and extends substantially circumferentially. The cord density in this band is 45 ends / 5 cm or less. The outer diameter of this cord is 0.75 mm or less. This cord is formed by twisting a plurality of strands. This cord has a single twist structure. The material of each strand is steel. In the above cord, two or more strands are wavy. The wave height of the corrugated element wire is 0.15 mm or more.

  Preferably, in this pneumatic tire, the ratio of the height in the radial direction of the tread to half the axial width of the tread is not less than 0.25 and not more than 1.0.

  Preferably, in the pneumatic tire, the band is laminated on the carcass.

  Preferably, in the pneumatic tire, the wave height is 0.50 mm or less.

  Preferably, in the pneumatic tire, the cord density in the band is 25 ends / 5 cm or more.

  Preferably, in this pneumatic tire, the outer diameter of the cord is 0.40 mm or more.

  In the pneumatic tire for a motorcycle according to the present invention, the cord included in the band is light. In addition, the wires constituting the cord include a wire having a wavy waveform. This cord has moderate compression rigidity. When the tire is mounted on the rim, the cord sufficiently cushions the compression force. In this tire, the shoulder does not wavy. With this tire, weight reduction is achieved without impairing steering stability.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a part of the tire of FIG. FIG. 3 is a cross-sectional view showing a cord included in the band of the tire of FIG. FIG. 4 is a side view showing a part of the strands included in the cord of FIG. FIG. 5 is a schematic diagram showing a state of adding a wave shape to a strand. FIG. 6 is a perspective view showing a sample for measuring the compression stiffness of the cord. FIG. 7 is a schematic view showing a state in which the compression stiffness of the cord is measured. FIG. 8 is a graph showing the measurement results of the compression stiffness of the cord. FIG. 9 is a cross-sectional view showing a part of a conventional tire. 10 is a cross-sectional perspective view showing a ribbon used for forming the band of the tire of FIG. FIG. 11 is a cross-sectional view showing a cord included in the tire band of FIG. 9. 12 is a cross-sectional view showing a cord different from the cord of FIG. FIG. 13 is a cross-sectional view showing a state where the tire of FIG. 9 is mounted on a rim.

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

  FIG. 1 shows a pneumatic tire 38. In FIG. 1, the vertical direction is the radial direction of the tire 38, the horizontal direction is the axial direction of the tire 38, and the direction perpendicular to the paper surface is the circumferential direction of the tire 38. In FIG. 1, an alternate long and short dash line CL represents the equator plane of the tire 38. The shape of the tire 38 is symmetrical with respect to the equator plane except for the tread pattern. As shown in the drawing, the tire 38 is attached to the rim 40. The rim 40 is a regular rim described later.

  The tire 38 includes a tread 42, a sidewall 44, a wing 46, a bead 48, a carcass 50, an inner liner 52, a chafer 54, and a band 56. The tire 38 is a tubeless type. The tire 38 is attached to a two-wheeled passenger car.

  The tread 42 is made of a crosslinked rubber having excellent wear resistance, heat resistance, and grip properties. The tread 42 has a shape protruding outward in the radial direction. The tread 42 forms a tread surface 58 that contacts the road surface. In the tire 38, the tread surface 58 is not grooved. Grooves may be cut into the tread surface 58 to form a tread pattern.

  As described above, the tire 38 is mounted on a two-wheeled vehicle. In straight running, the equator portion (center) of the tire 38 is mainly in contact with the road surface. When turning, the rider tilts the vehicle. In cornering, the end portion (shoulder) of the tread 42 of the tire 38 mainly contacts the road surface.

  In FIG. 1, the symbol E represents the end of the tire 38 in the axial direction. This end E is a reference point that defines the profile of the tread surface 58. A double-headed arrow W represents the axial width from the equator plane to the end E. In the present application, this width W represents half of the axial width of the tread 42. A double-headed arrow H represents the height in the radial direction from the equator to this end E. In the present application, the height H represents the radial height of the tread 42. In addition, when the groove | channel is carved in the tread surface 58, the height H is represented based on the tread surface 58 when this groove | channel is not provided.

  In the tire 38, from the viewpoint that an appropriate profile of the tread surface 58 is obtained, the ratio of the height H to the width W is preferably 0.25 or more, and more preferably 1.0 or less.

  The sidewall 44 extends from the end of the tread 42 substantially inward in the radial direction. The sidewall 44 is made of a crosslinked rubber having excellent cut resistance and weather resistance. The side wall 44 prevents the carcass 50 from being damaged.

  The wing 46 is located between the tread 42 and the sidewall 44. The wing 46 is joined to each of the tread 42 and the sidewall 44. The wing 46 is made of a crosslinked rubber having excellent adhesiveness.

  The bead 48 is located substantially inward of the sidewall 44 in the radial direction. The bead 48 includes a core 60 and an apex 62 that extends radially outward from the core 60. The core 60 is ring-shaped and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 62 is tapered outward in the radial direction. The apex 62 is made of a highly hard crosslinked rubber.

  The carcass 50 is located inside the tread 42 and the sidewalls 44. The carcass 50 of the tire 38 includes a ply 64. The ply 64 is spanned between the beads 48 on both sides, and extends along the tread 42 and the sidewall 44. The ply 64 is folded around the core 60 from the inner side to the outer side in the axial direction. By this folding, the ply 64 is formed with a main portion 64a and a folding portion 64b.

  In the tire 38, the ply 64 includes a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane is 75 ° to 90 °. In other words, the carcass 50 has a radial structure. The cord is made of organic fiber. Preferred organic fibers include polyethylene terephthalate fiber, nylon fiber, rayon fiber, polyethylene naphthalate fiber and aramid fiber. The carcass 50 may be formed from two or more plies 64.

  The inner liner 52 is located inside the carcass 50. The inner liner 52 is joined to the inner surface of the carcass 50. The inner liner 52 is made of a crosslinked rubber. For the inner liner 52, rubber having excellent air shielding properties is used. A typical base rubber of the inner liner 52 is butyl rubber or halogenated butyl rubber. The inner liner 52 holds the internal pressure of the tire 38.

  The chafer 54 is located in the vicinity of the bead 48. When the tire 38 is incorporated into the rim 40, the chafer 54 contacts the rim 40. By this contact, the vicinity of the bead 48 is protected. The chafer 54 is made of cloth and rubber impregnated in the cloth. The chafer 54 may be formed from a single rubber.

  The band 56 is located on the radially inner side of the tread 42 and on the radially outer side of the carcass 50. The band 56 extends along the carcass 50 from the equator plane toward the end of the tread 42. In the tire 38, the band 56 is laminated on the carcass 50 without interposing other members.

  FIG. 2 is an enlarged view of a part of the band 56 of FIG. 1 together with other members. In FIG. 2, the direction perpendicular to the paper surface is the circumferential direction of the tire 38. As shown, the band 56 includes a cord 66 and a topping rubber 68. The cord 66 is wound spirally. The band 56 has a so-called jointless structure. The cord 66 extends substantially in the circumferential direction. The angle of the cord 66 with respect to the circumferential direction is 5 ° or less, and further 2 ° or less.

  The band 56 can contribute to the radial rigidity of the tire 38. The band 56 can suppress the influence of centrifugal force that acts during traveling. The tire 38 is excellent in high speed stability.

  Shown in FIG. 3 is a cross section of a cord 66 included in a band 56. The code 66 is composed of a plurality of strands 70. The material of each strand 70 is steel. This cord 66 is called a steel cord. The outer diameter of the strand 70 is not less than 0.10 mm and not more than 0.40 mm. In the tire 38, from the viewpoint of the rigidity of the cord 66, the number of the strands 70 constituting the cord 66 is preferably 3 or more, and more preferably 4 or more. In view of the mass of the cord 66, the number of the strands 70 constituting the cord 66 is preferably 10 or less, and more preferably 7 or less.

  In the tire 38, the cord 66 of the band 56 is formed by twisting five strands 70. The cord 66 has a single twist structure. The configuration of the code 66 is expressed as “1 × 5”. The cord 66 is lighter than the double twisted cord 22 shown in FIG. The cord 66 can contribute to weight reduction of the tire 38. In FIG. 3, a circumscribed circle of the cord 66 is indicated by a two-dot chain line DM. In the present application, the outer diameter D of the cord 66 is represented by the diameter of the circumscribed circle DM.

  In the tire 38, the cord 66 of the band 56 includes an element wire 70a with a corrugation. In the cord 66 shown in FIG. 3, the two strands 70 are corrugated strands 70a. In FIG. 3, what is indicated by a two-dot chain line SCa is a circumscribed circle of the strand 70a.

  In the present invention, a wire 70a having a waveform is obtained using the device 72 shown in FIG. This device 72 includes two rollers 74. Each of the rollers 74 includes a main body 76 and a plurality of convex portions 78. The main body 76 has a disk shape. The plurality of convex portions 78 are arranged on the side surface of the main body 76 with a space therebetween. In the device 72, the shape of the convex portion 78 is not particularly limited. The shape of the convex portions 78 and the interval between the convex portions 78 are appropriately determined according to the specification of the waveform of the strand 70a. In the apparatus 72 shown in FIG. 4, each convex part 78 is comprised so that the outer surface may be rounded.

  In this device 72, the roller 74 located on the upper side rotates around the point P1 in the direction indicated by the arrow D1. The roller 74 located on the lower side rotates around the point P2 in the direction indicated by the arrow D2. In this device 72, a concave portion 80 is formed between one convex portion 78 and another convex portion 78 located next to the one convex portion 78. When both rollers 74 rotate, for example, the convex portion 78 of the upper roller 74 is fitted into the concave portion 80 of the lower roller 74. The convex portion 78 of the lower roller 74 is fitted into the concave portion 80 of the upper roller 74.

  In this device 72, an uncorrugated wire 70 b is passed between both rollers 74. Thereby, the linear strand 70b is processed into a zigzag shape. In this way, the strand 70a having the wavy shape shown in FIG. 5 is obtained.

  As shown in FIG. 5, the wire 70 a with a wavy corrugation has a form in which a plurality of peaks 82 are connected in the length direction. In the strand 70 a, a valley 84 is formed between one mountain 82 and another mountain 82 located next to the one mountain 82. The crest 82 of the strand 70a is formed by sandwiching an uncorrugated strand 70b between the concave portion 80 of the upper roller 74 and the convex portion 78 of the lower roller 74. The trough 84 of the strand 70a is formed by sandwiching a strand 70b having no waveform between the concave portion 80 of the lower roller 74 and the convex portion 78 of the upper roller 74.

  As described above, in the tire 38, the cord 66 of the band 56 includes the strand 70a having a wavy shape. The corrugated element wire 70 a can contribute to buffering the compressive force in the length direction of the cord 66. The wire 70a having this waveform affects the compression rigidity of the cord 66 in its length direction. In the tire 38, the cord 66 of the band 56 includes the corrugated element wire 70a, so that the compression rigidity of the cord 66 is appropriately adjusted.

  In the present application, the compression rigidity of the cord 66 is obtained by measuring the stress strain curve of the cord 66. The stress strain curve of the cord 66 is measured as follows.

  A sample 86 shown in FIG. 6 is prepared for the measurement of the stress distortion curve. This sample 86 is a cylindrical block composed of a cord 66 and a crosslinked rubber 88. The outer diameter of the sample 86 is about 25 mm. The length of the cord 66 used for this measurement is 25 mm.

  In this sample 86, the cord 66 is covered with a crosslinked rubber 88. The crosslinked rubber 88 supports the cord 66. In this measurement, the crosslinked rubber 88 is not particularly limited. The cross-linked rubber 88 of the sample 86 shown in FIG. 6 is formed from a rubber composition equivalent to the rubber composition that forms the topping rubber 68 of the band 56.

  As shown, the cord 66 is located at the center of the sample 86. The cord 66 extends from one end surface 90 of the sample 86 toward the other end surface 90. In other words, the cord 66 extends in the length direction of the sample 86.

  A test machine is used to measure the stress strain curve. The tester is not particularly limited as long as it has a stage and a load cell and can perform a compression test. As this testing machine, for example, trade name “MODEL-2005” manufactured by INTESCO is listed.

  In the measurement of the stress strain curve, the sample 86 is set on a testing machine. The state at this time is shown in FIG. In this measurement, a jig 92 is disposed between the stage of the testing machine and the load cell. In FIG. 7, the stage of the testing machine and the load cell are not shown. In the present application, this measurement is performed at room temperature.

  The jig 92 includes an upper plate 94 and a lower plate 96. The upper plate 94 is fixed to the load cell of the testing machine. The lower plate 96 is placed on the stage of the testing machine. The sample 86 is placed on the lower plate 96 with one end face 90 thereof facing down. The other end surface 90 of the sample 86 is brought into contact with the upper plate 94. As a result, the sample 86 is sandwiched between the upper plate 94 and the lower plate 96. As described above, the cord 66 extends from one end surface 90 toward the other end surface 90. Therefore, when the sample 86 is set in the testing machine, the cord 66 extends from the upper plate 94 toward the lower plate 96.

  In the measurement of the stress strain curve, the upper plate 94 is lowered toward the lower plate 96. The state at this time is shown in FIG. In FIG. 7B, the moving direction of the upper plate 94 is indicated by an arrow B. As the upper plate 94 is lowered, the sample 86 is compressed. In this measurement, the lowering speed of the upper plate 94 is set to 2.0 mm / min.

  In the measurement of the stress strain curve, the moving direction of the upper plate 94 coincides with the length direction of the cord 66 in the sample 86 set in the testing machine. Therefore, the cord 66 is compressed in the length direction by the lowering of the upper plate 94. In this testing machine, the load applied to the strain applied by compressing the cord 66 in its length direction is measured by a load cell. As a result, a stress strain curve of the cord 66 is obtained.

  FIG. 8 is a graph showing the relationship of the load (N) to the strain (%) applied to the cord 66. In this graph, a stress strain curve 98 of the cord 66 is drawn. As shown in the figure, the stress strain curve 98 of the cord 66 has a portion where the load rapidly increases with respect to the strain change. In this part, the relationship between strain and load is approximated by a linear function (solid line L1 in FIG. 8). In the present application, the slope of this linear function is used as the compression stiffness of the cord 66. The unit of this compression rigidity is N / mm.

  In the tire 38, the cord 66 of the band 56 has appropriate compression rigidity. Specifically, the compression stiffness of the cord 66 is smaller than the compression stiffness of a cord formed by twisting a plurality of uncorrugated strands, for example, the cord 30 shown in FIG. . Therefore, when the tire 38 is mounted on the rim 40, the cord 66 sufficiently buffers the compression force generated by the mounting. In the tire 38, the shoulder does not wavy. In the tire 38, steering stability is appropriately maintained. As described above, the cord 66 of the tire 38 is lighter than the double twisted cord 22 shown in FIG. In the tire 38, weight reduction is achieved without impairing steering stability.

  In the tire 38, the compression rigidity of the cord 66 is preferably 400 N / mm or less from the viewpoint that the occurrence of undulations in the shoulder is effectively prevented. From the viewpoint of maintaining the rigidity of the band 56 appropriately, the compression rigidity of the cord 66 is preferably 200 N / mm or more.

  In the tire 38, the cord 66 of the band 56 has two or more strands 70 that are corrugated. The cord 66 has an appropriate compression rigidity. The cord 66 sufficiently cushions the compressive force generated when the tire 38 is attached to the rim 40. In the tire 38, the shoulder does not wavy. The tire 38 is excellent in handling stability. From the standpoint that the rigidity of the band 56 is appropriately maintained, at least one of the plurality of strands 70 forming the cord 66 of the band 56 is preferably a strand 70b that is not wavy. . More preferably, two or more strands 70b that are not wavy are included. Therefore, in the cord 66 shown in FIG. 3, the number of the strands 70a having a wavy shape is preferably 4 or less, and more preferably 3 or less.

  In the tire 38, from the viewpoint that the cord 66 included in the band 56 has appropriate compression rigidity, the ratio of the number of the corrugated strands 70a to the total number of the strands 70 constituting the cord 66 is 40% or more. Is preferred. This ratio is preferably 80% or less, and more preferably 60% or less.

  In the tire 38, the outer diameter D of the cord 66 of the band 56 is 0.75 mm or less. Thereby, the compression rigidity of the cord 66 is appropriately maintained. In the tire 38, the cord 66 sufficiently cushions the compression force generated when the tire 38 is mounted on the rim 40. In the tire 38, the shoulder does not wavy. The tire 38 is excellent in handling stability. In this respect, the outer diameter D is more preferably 0.70 mm or less. From the viewpoint that the rigidity of the band 56 is appropriately maintained, the outer diameter D is preferably 0.35 mm or more, and more preferably 0.40 mm or more.

  In FIG. 5, a double-headed arrow hw represents the height of the wave in the waveform wire 70a. The height hw is represented by the swing width from the top 100 of the peak 82 of the strand 70a to the bottom 102 of the valley 84 of the strand 70a. The double arrow P represents the pitch of the waveform. This pitch P is represented by the length from the top 100 of one mountain 82 to the top 100 of another mountain 82 located next to this one mountain 82. The height hw and the pitch P are measured before being twisted with the other strands 70.

  In the tire 38, the height hw is 0.15 mm or more. Thereby, the cord 66 has an appropriate compression rigidity. In the tire 38, the cord 66 sufficiently cushions the compression force generated when the tire 38 is mounted on the rim 40. In the tire 38, the shoulder does not wavy. The tire 38 is excellent in handling stability. From this viewpoint, the height hw is preferably 0.20 mm or more. From the viewpoint that the rigidity of the band 56 is appropriately maintained, the height hw is preferably 0.60 mm or less, and more preferably 0.50 mm or less.

  In the tire 38, the pitch P is preferably 2.0 mm or more and preferably 5.0 mm or less from the viewpoint that the cord 66 of the band 56 has an appropriate compression rigidity.

  In the tire 38, the density of the cord 66 in the band 56 is 45 ends / 5 cm or less. Thereby, the rigidity of the band 56 is appropriately maintained. In addition, the cord 66 included in the band 56 can sufficiently contribute to buffering the compression force generated when the tire 38 is attached to the rim 40. In the tire 38, the shoulder does not wavy. The tire 38 is excellent in handling stability. From the viewpoint that the band 56 has an appropriate rigidity, the density of the cord 66 is preferably 20 ends / 5 cm or more, and more preferably 25 ends / 5 cm or more. This density is obtained by measuring the number (ends) of the cross sections of the cords 66 existing around the 5 cm width of the band 56 in the cross section perpendicular to the longitudinal direction of the cords 66 of the band 56.

  In the present invention, the size and angle of each member of the tire 38 are measured in a state where the tire 38 is incorporated in a normal rim and the tire 38 is filled with air so as to have a normal internal pressure. During the measurement, no load is applied to the tire 38. In the present specification, the normal rim means a rim defined in a standard on which the tire 38 is based. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In the present specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 38 is based. “Maximum air pressure” in JATMA standard, “maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “INFLATION PRESSURE” in ETRTO standard are normal internal pressures.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
A pneumatic tire for a motorcycle according to Example 1 having the basic configuration shown in FIG. 1 and having the specifications shown in Table 1 below was obtained. The size of the tire was 180 / 55ZR17. The cord density in the tire band was 35 ends / 5 cm. The outer diameter D of the band cord was 0.50 mm. The configuration of this code was “1 × 5”. Of the five strands that make up this cord, two strands were corrugated. The wave height of the corrugated element wire was 0.25 mm. The compression rigidity of this cord was 330 N / mm.

[Example 2-4 and Comparative Example 2]
Tires of Examples 2-4 and Comparative Example 2 were obtained in the same manner as in Example 1 except that the number of corrugated wires included in the cord was as shown in Table 1 below.

[Examples 5-9 and Comparative Example 3]
Tires of Examples 5-9 and Comparative Example 3 were obtained in the same manner as in Example 1 except that the wave height hw was as shown in Table 2 below.

[Examples 10-12 and Comparative Example 4]
Tires of Examples 10-12 and Comparative Example 4 were obtained in the same manner as Example 1 except that the outer diameter D was as shown in Table 3 below.

[Examples 13-15 and Comparative Example 5]
Tires of Examples 13-15 and Comparative Example 5 were obtained in the same manner as in Example 1 except that the cord density in the band was as shown in Table 4 below.

[Comparative Example 1]
A tire of Comparative Example 1 was obtained in the same manner as in Example 1 except that the cord shown in FIG. 11 was used as the cord of the band. This code does not include a waveform wire. This comparative example 1 is a conventional tire.

[Appearance when wearing]
The tire was mounted on a rim (size = 17 × MT5.50). The tire was filled with air so that the internal pressure was 290 kPa. By observing and palpating the surface of the tire, the occurrence of undulation was confirmed. The results are shown in Tables 1 to 4 below, where “G” indicates no undulation and “NG” indicates undulation.

[Steering stability, feeling of ground contact, vibration and wear resistance]
The tire was assembled in a rim (size = 17 × MT5.50), and the tire was filled with air so that the internal pressure was 290 kPa. This tire was mounted on a motorcycle having a displacement of 1000 cm ³ . Riders were allowed to drive the motorcycle on a racing circuit to evaluate steering stability, ground contact and vibration. The results are shown in Tables 1 to 4 below as indices. Larger numbers are preferable. The reference point is 3.0.

  The appearance of the tire after running was observed to confirm the occurrence of uneven wear. The results are shown in Tables 1 to 4 below, where “G” indicates no occurrence of uneven wear and “NG” indicates occurrence of uneven wear.

[Mass of tire]
The mass of the tire was measured. The results are shown in the following Tables 1 to 4 as index values with Comparative Example 1 as 100. The smaller the value, the lighter.

  As shown in Tables 1 to 4, the tire of the example has a higher evaluation than the tire of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The method described above can be applied to various pneumatic tires.

2, 38 ... Tire 4, 42 ... Tread 6, 44 ... Sidewall 10, 48 ... Bead 12, 50 ... Carcass 18, 56 ... Band 22, 30, 66 ...・ Code 26, 32, 70, 70a, 70b ...

Claims (7)

A tread whose outer surface forms a tread surface; a pair of sidewalls each extending substantially inward in the radial direction from an end of the tread; a pair of beads each positioned substantially inward in the radial direction from the sidewall; A carcass spanned between one bead and the other bead along the inside of the tread and the sidewall, and a band located radially outside the carcass inside the tread ,
The carcass has a radial structure,
The band includes a cord wound in a spiral and extending substantially circumferentially;
The cord density in this band is 25 ends / 5 cm or more and 45 ends / 5 cm or less,
The outer diameter of this cord is 0.75 mm or less,
This cord is formed by twisting multiple strands,
This cord has a single twist structure,
The material of each strand is steel,
In the above cord, two or more strands are wrinkled with a waveform at a constant pitch,
The wave height in the wire of this waveform is 0.15 mm or more,
Among a plurality of wires constituting the cord, at least one, Ri wires der the habit of the waveform is not attached,
Compressive stiffness of the cord, Ru der below 315N / mm or more 335n / mm, two-wheel pneumatic tires for motor vehicles.   The pneumatic tire for a motorcycle according to claim 1, wherein a ratio of a radial height of the tread to a half of an axial width of the tread is 0.25 or more and 1.0 or less.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the band is laminated on the carcass.   The pneumatic tire for a two-wheeled vehicle according to any one of claims 1 to 3, wherein the wave height is 0.50 mm or less. The pneumatic tire for a motorcycle according to any one of claims 1 to 4 , wherein an outer diameter of the cord is 0.40 mm or more. The pneumatic tire for a two-wheeled vehicle according to any one of claims 1 to 5 , wherein a ratio of the number of strands of the waveform to the total number of strands constituting the cord is 40% or more and 80% or less. The pneumatic tire for a motorcycle according to any one of claims 1 to 6 , wherein a pitch of the waveform is 2.0 mm or greater and 5.0 mm or less.

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