JP2017024714A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire 2 suppressing generation of bare.SOLUTION: A tire 2 comprises a tread 4 whose outer surface forms a tread surface 24. A main groove 50 extending in a circumferential direction is engraved on the tread 4. The depth of the main groove 50 is 6 mm or more. A width WG of the main groove 50 is equal to a depth DG of the main groove 50, or the width WG of the main groove 50 is larger than the depth DG of the main groove 50. A ratio of the width WG of the main groove 50 to the width of the tread surface 24 is 6% or more. The main groove 50 is provided with a wear indicator 60. The wear indicator 60 protrudes radially outward from a bottom 54 of the main groove 50. Thin film-like bridges 66 are provided outside the wear indicator 60 in a radially outward direction. The bridges 66 connect the wear indicator 60 and side walls 56 of the main groove 50.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a pneumatic tire.

  Grooves are carved into the tread of the tire. This groove contributes to the discharge of water existing between the road surface and the tire during rainy weather. Thereby, the occurrence of the hydroplaning phenomenon is prevented.

  The tread is made of a crosslinked rubber. The tread wears with use. Wear results in shallow grooves. Shallow grooves affect drainage. If drainage is reduced, hydroplaning may occur.

  It is important to know the degree of wear in a tire. For this purpose, a wear indicator may be provided on the tire.

  The wear indicator is usually provided in a groove extending in the circumferential direction (hereinafter referred to as a main groove). The wear indicator projects outward from the bottom of the main groove. The wear indicator has a height.

  As the tread wears, the wear indicator will eventually be exposed. The height of the wear indicator is adjusted to the depth of the groove, which may reduce the drainage as the wear progresses further. The driver can grasp the degree of wear by checking the degree of exposure of the wear indicator.

  The outer surface of the tire is shaped by the cavity surface of the mold. In the tire mold having the above-described wear indicator, the cavity surface has a protrusion to cut the main groove in the tread. In order to provide a wear indicator in the main groove, the protrusion of the mold has a recess. The ridge has a top surface corresponding to the bottom of the main groove. The depression is recessed from this top surface.

  In the manufacture of tires, the raw cover (uncrosslinked tire) is put into an open mold. After charging, the mold is closed. The raw cover is pressurized and heated in the mold. The cavity surface is in contact with the raw cover. The ridges go into the raw cover.

  In the manufacture of this tire, when the ridge sinks into the raw cover, the top surface of the ridge contacts the raw cover. As described above, the depression is recessed from this top surface. For this reason, air tends to remain between the recess and the raw cover.

  The remaining air invites the bear. In a tire having a wear indicator, a bear is likely to be generated in the wear indicator. Bears detract from the appearance of the wear indicator, in other words, the tires.

  Various studies have been made from the viewpoint of suppressing the generation of bears and obtaining a tire having a good appearance. An example of this study is disclosed in JP2013-180707A. In the tire described in this publication, the wear indicator is provided with a recess. Thereby, the volume of the wear indicator is reduced.

  In the manufacture of tires, the rubber causes a crosslinking reaction by heating. This crosslinking reaction is accompanied by the formation of by-products. In the mold, many tires are manufactured. For this reason, by-products tend to accumulate on the cavity surface of the mold. If the by-product accumulates excessively, the deposit will impair the appearance quality of the tire. From the viewpoint of the appearance quality of the tire, the mold is periodically cleaned. In this cleaning, an abrasive is sprayed from the spray gun toward the cavity surface, and dirt on the cavity surface is scraped off by the sprayed abrasive. Such a cleaning method is called blast cleaning.

JP 2013-180707 A

  In the mold for a tire described in the above publication, a cavity for a wear indicator is provided on the cavity surface. Further, because of the concave portion of the wear indicator, a convex portion is provided at the bottom of the depression.

  As described above, in the mold cleaning, the abrasive is sprayed onto the cavity surface. The aforementioned convex part is thin and small. For this reason, the convex portion may be worn away by this cleaning. When the convex portion wears out, the concave portion cannot be formed in the wear indicator. In this tire, when the mold is used over a long period of time while cleaning the mold, there is a possibility that the effect of the concave portion cannot be maintained. Moreover, the effect of suppressing the bear by the recess is not sufficient.

  In a tire having a wear indicator, the generation of bears is not sufficiently and stably suppressed. In this tire, a technique for suppressing the generation of bears is in the process of being established.

  An object of the present invention is to provide a pneumatic tire in which generation of bears is suppressed.

  The pneumatic tire according to the present invention includes a tread whose outer surface forms a tread surface. The tread has a main groove extending in the circumferential direction. The depth of the main groove is 6 mm or more. The width of the main groove is equal to the depth of the main groove, or the width of the main groove is larger than the depth of the main groove. The ratio of the width of the main groove to the width of the tread surface is 6% or more. A wear indicator is provided in the main groove. The wear indicator protrudes radially outward from the bottom of the main groove. The wear indicator is provided with a thin-film connection. This tether is located radially outward of the wear indicator. This tether is connected to the wear indicator and the side wall of the main groove.

  Preferably, in the pneumatic tire, the connection includes an edge that bridges between the wear indicator and the side wall. The outline of the edge is an arc. The radius of curvature of the arc is 4 mm or more.

  Preferably, in the pneumatic tire, the thickness of the connection is 0.3 mm or more and 1.2 mm or less.

  Preferably, in this pneumatic tire, the wear indicator is provided with a plurality of the linkages. These linkages are arranged at intervals in the circumferential direction. This interval is 2 mm or more.

  Preferably, in the pneumatic tire, the plurality of links connect the wear indicator and one side wall of the main groove, and connect the wear indicator and the other side wall of the main groove. Includes a second binder.

  Preferably, in the pneumatic tire, when the tire is configured to be attached to the vehicle such that one end of the tread surface is located inside the vehicle, the number of the second nails is More than the number of first nails.

  Preferably, the pneumatic tire further includes a reinforcing layer on a radially inner side of the tread. The thickness from the bottom of the main groove to the reinforcing layer is 1.3 mm or more.

  Preferably, the pneumatic tire includes an edge that bridges the link between the wear indicator and the side wall. The edge comprises two planes that are inclined with respect to the side wall. The angle formed by one plane near the side wall with respect to the side wall is smaller than the angle formed by the other plane with respect to the side wall.

  A mold for manufacturing a pneumatic tire according to the present invention has a toroidal cavity surface. The cavity surface has a protrusion extending in the circumferential direction. The said protrusion has the main hollow dented from the top surface. The main recess has a sub-recess further recessed from the bottom. A corner is formed by the bottom of the main recess and the side surface of the protrusion. The sub-recess is located at the corner.

A method for manufacturing a pneumatic tire according to the present invention includes:
(1) A step of preparing a raw cover (2) a step of putting the raw cover into a mold, and (3) a step of pressurizing and heating the raw cover in the mold. The mold includes a toroidal cavity surface. The cavity surface has a protrusion extending in the circumferential direction. The said protrusion has the main hollow dented from the top surface. The main recess has a sub-recess further recessed from the bottom. A corner is formed by the bottom of the main recess and the side surface of the protrusion. The sub-recess is located at the corner.

  In the pneumatic tire according to the present invention, the connection connecting the wear indicator and the side wall of the main groove contributes to the discharge of air. In this tire, residual air is suppressed. Since the rubber flow failure due to the remaining air is suppressed, the occurrence of bear due to the rubber flow failure is effectively suppressed. According to the present invention, a pneumatic tire in which generation of bears is suppressed can be obtained.

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 a development view showing a tread surface of the tire of FIG. 1. FIG. 3 is a schematic view showing the wear indicator of the tire of FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a plan view showing a part of a mold for manufacturing the tire of FIG. 1. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a schematic diagram showing a wear indicator having an aspect different from the aspect of the wear indicator shown in FIG. 3. FIG. 9 is an enlarged cross-sectional view showing a part of a pneumatic tire according to another embodiment.

  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 2. In FIG. 1, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In FIG. 1, an alternate long and short dash line CL represents the equator plane of the tire 2. The shape of the tire 2 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 2 includes a tread 4, a pair of sidewalls 6, a pair of clinch 8, a pair of beads 10, a carcass 12, a belt 14, a band 16, an inner liner 18, a pair of cushion layers 20, and a pair of chafers 22. ing. The tire 2 is a tubeless type. The tire 2 is mounted on a passenger car.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 24 that contacts the road surface. In other words, the outer surface of the tread 4 forms a tread surface 24.

  In FIG. 1, the symbol TE represents a specific position on the outer surface of the tire 2. The position TE is a boundary between the tread 4 and the sidewall 6 on the outer surface of the tire 2. In the present invention, this position TE is the end of the tread surface 24.

  The tread 4 has a base layer 26 and a cap layer 28. The cap layer 28 is located on the outer side in the radial direction of the base layer 26. The cap layer 28 is laminated on the base layer 26. The base layer 26 is made of a crosslinked rubber having excellent adhesiveness. A typical base rubber of the base layer 26 is natural rubber. The cap layer 28 is made of a crosslinked rubber having excellent wear resistance, heat resistance, and grip properties.

  The tread 4 further includes a pair of wings 30. Each wing 30 is located between the main body 32 of the tread 4 including the cap layer 28 and the base layer 26 and the sidewall 6. The wing 30 is joined to each of the main body 32 and the sidewall 6 of the tread 4. The wing 30 is made of a crosslinked rubber having excellent adhesiveness.

  In FIG. 1, the double arrow TT is the thickness of the tread 4. In the present invention, the thickness TT is represented by the length from the inner surface of the tread 4 to the outer surface (tread surface 24) on the equator plane. In addition, in the case where a main groove described later is provided on the equator of the tire 2 (position on the tread surface 24 indicated by the symbol EQ in FIG. 1), in a place near the equator surface and without this main groove, The measured thickness of the tread 4 is used as the thickness TT.

  In the tire 2, the thickness TT of the tread 4 is preferably 7.3 mm or more from the viewpoint of exhibiting the performance. From the viewpoint of suppressing the influence on mass and rolling resistance due to the large thickness TT, the thickness TT is preferably 11 mm or less. From the viewpoint of suppressing heat generation in the tread 4 and further improving high-speed durability, the thickness TT is more preferably 10 mm or less, further preferably 9 mm or less, and particularly preferably 8 mm or less.

  Each sidewall 6 extends substantially inward in the radial direction from the tread 4. This sidewall 6 is made of a crosslinked rubber having excellent cut resistance and weather resistance. This sidewall 6 prevents the carcass 12 from being damaged.

  Each clinch 8 is located substantially inside the sidewall 6 in the radial direction. The clinch 8 is located outside the beads 10 and the carcass 12 in the axial direction. The clinch 8 is made of a crosslinked rubber having excellent wear resistance. Although not shown, the clinch 8 contacts the rim flange.

  Each bead 10 is located inside the clinch 8 in the axial direction. The bead 10 includes a core 34 and an apex 36 that extends radially outward from the core 34. The core 34 is ring-shaped and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 36 is tapered outward in the radial direction. The apex 36 is made of a highly hard crosslinked rubber.

  The carcass 12 includes a first ply 38 and a second ply 40. The first ply 38 and the second ply 40 are bridged between the beads 10 on both sides, and extend along the tread 4 and the sidewall 6. Each of the first ply 38 and the second ply 40 is folded around the core 34 from the inner side to the outer side in the axial direction.

  Although not shown, each of the first ply 38 and the second ply 40 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 12 has a radial structure. The cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. The carcass 12 may be formed from a single ply.

  The belt 14 is located on the inner side in the radial direction of the tread 4. The belt 14 is laminated with the carcass 12. The belt 14 reinforces the carcass 12. The belt 14 includes an inner layer 42 and an outer layer 44. As apparent from FIG. 1, the width of the inner layer 42 is slightly larger than the width of the outer layer 44 in the axial direction. Although not shown, each of the inner layer 42 and the outer layer 44 is composed of a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equator plane. The general absolute value of the tilt angle is 10 ° or more and 35 ° or less. The inclination direction of the cord of the inner layer 42 with respect to the equator plane is opposite to the inclination direction of the cord of the outer layer 44 with respect to the equator plane. A preferred material for the cord is steel. An organic fiber may be used for the cord. The axial width of the belt 14 is preferably 0.7 times or more the maximum width of the tire 2. The belt 14 may include three or more layers.

  The band 16 is located on the radially outer side of the belt 14. In the axial direction, the width of the band 16 is larger than the width of the belt 14. Although not shown, the band 16 is composed of a cord and a topping rubber. The cord is wound in a spiral. The band 16 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is 5 ° or less, and further 2 ° or less. Since the belt 14 is restrained by this cord, lifting of the belt 14 is suppressed. The cord is made of organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The belt 14 and the band 16 constitute a reinforcing layer 46. The reinforcing layer 46 is located inside the tread 4 in the radial direction. In other words, the tire 2 includes a reinforcing layer 46 located on the inner side in the radial direction of the tread 4. In the tire 2, the reinforcing layer 46 may be configured only from the belt 14. The reinforcing layer 46 may be formed only from the band 16.

  The inner liner 18 is located inside the carcass 12. The inner liner 18 is joined to the inner surface of the carcass 12. The inner liner 18 is made of a crosslinked rubber having excellent air shielding properties. A typical base rubber of the inner liner 18 is butyl rubber or halogenated butyl rubber. The inner liner 18 maintains the internal pressure of the tire 2.

  Each cushion layer 20 is laminated with the carcass 12 in the vicinity of the end of the belt 14. The cushion layer 20 is made of a soft crosslinked rubber. The cushion layer 20 absorbs stress at the end of the belt 14. The cushion layer 20 suppresses lifting of the belt 14.

  Each chafer 22 is located in the vicinity of the bead 10. When the tire 2 is incorporated into the rim, the chafer 22 comes into contact with the rim. By this contact, the vicinity of the bead 10 is protected. In this embodiment, the chafer 22 is made of cloth and rubber impregnated in the cloth. The chafer 22 may be made of the same material as that of the clinch 8. In this case, the chafer 22 is integral with the clinch 8.

  FIG. 2 shows a part of the tread surface 24 of the tire 2. In FIG. 2, the vertical direction is the circumferential direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the radial direction of the tire 2.

  A plurality of grooves 48 are formed in the tread 4 of the tire 2. These grooves 48 form a tread pattern. A portion of the tread surface 24 other than the groove 48 is also referred to as a land.

  As apparent from FIG. 2, the tread pattern in the zone Z1 (hereinafter referred to as the first zone) from the equator plane to one end TE1 (hereinafter referred to as the first end) of the tread 4 and the other side of the tread 4 from the equator plane. This is different from the tread pattern in the zone Z2 (hereinafter referred to as the second zone) up to the end TE2 (hereinafter referred to as the second end). The tread pattern of the tire 2 is not symmetric with respect to the equator plane. This tread pattern is asymmetric with respect to the equator plane. The tire 2 is attached to the vehicle such that the first end TE1 of the tread surface 24 is located inside the vehicle and the second end TE2 of the tread surface 24 is located outside the vehicle.

  In the tire 2, the plurality of grooves 48 constituting the tread pattern include a plurality of main grooves 50 extending continuously in the circumferential direction. In other words, a plurality of main grooves 50 extending in the circumferential direction are carved in the tread 4 of the tire 2. In the case of the tire 2, three main grooves 50 are carved in the tread 4. In the present specification, the main groove 50a located on the rightmost side in FIG. 2 is also referred to as a first main groove, and the main groove 50b located on the left side of the first main groove 50a is referred to as a second main groove. The main groove 50c located further to the left of the second main groove 50b is also referred to as a third main groove.

  In the tire 2, the number of main grooves 50 included in the first zone Z1 is larger than the number of main grooves 50 included in the second zone Z2. This is because the ground contact surface is formed so that the ground contact area in the first zone Z1 inside the vehicle is larger than the ground contact area in the second zone Z2 outside the vehicle when the tire 2 is traveling straight ahead. Because.

  In FIG. 2, the double arrow WT is the width of the tread surface 24. The width WT is represented by the length from the first end TE1 of the tread surface 24 to the second end TE2. A double-headed arrow WG is the width of the main groove 50. This width WG is represented by the length from one edge 52 of the main groove 50 to the other edge 52.

  In the tire 2, the ratio of the width WG of the main groove 50 to the width WT of the tread surface 24 is 6% or more. As a result, a sufficient width WG is secured in the main groove 50. In the tire 2, the main groove 50 contributes to drainage. In the tire 2, good drainage is achieved. The width WG of the main groove 50 affects the contact area of the tread surface 24. From the standpoint of sufficiently securing the ground contact surface, this ratio is preferably 15% or less.

  FIG. 3 shows a part of the first main groove 50a in FIG. In FIG. 3, the vertical direction is the circumferential direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the radial direction of the tire 2. FIG. 4 shows a cross section taken along line IV-IV in FIG. In FIG. 4, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2.

  The main groove 50 includes a bottom 54 and a pair of side walls 56. Each side wall 56 extends from the bottom 54 substantially outward in the radial direction. The side wall 56 and the bottom 54 form a corner 58. In other words, there is a corner 58 between the side wall 56 and the bottom 54. As is apparent from FIG. 4, the corner 58 between the side wall 56 and the bottom 54, that is, the corner 58 of the main groove 50 is rounded. In FIG. 4, an arrow Ra is the radius of curvature of the corner 58. In the tire 2, the radius of curvature Ra of the arc representing the corner 58 is not less than 1 mm and not more than 4 mm.

  In FIG. 4, the double arrow DG is the depth of the main groove 50. This depth DG is represented by the length from the tread surface 24 to the bottom 54 of the main groove 50. If the bottom 54 is not flat, this depth DG is represented by the maximum depth. In FIG. 4, the double arrow TG represents the thickness from the bottom 54 of the main groove 50 to the reinforcing layer 46. This thickness TG is also referred to as a groove bottom gauge. When the bottom 54 of the main groove 50 is not flat, the thickness TG is expressed as a minimum thickness.

  In the tire 2, the depth DG of the main groove 50 is 6 mm or more. Thereby, a sufficient depth DG is ensured in the main groove 50. In the tire 2, the main groove 50 contributes to drainage. In the tire 2, good drainage is achieved. In this respect, the depth DG is preferably 6.0 mm or more, and more preferably 7.0 mm or more.

  As described above, the reinforcing layer 46 is located inside the tread 4 in the radial direction. If a large depth DG is adopted for the main groove 50, the bottom 54 of the main groove 50 may be broken, and the reinforcing layer 46 may be exposed. In the tire 2, the thickness TG is preferably set to 1.3 mm or more. Thereby, the thickness from the bottom 54 of the main groove 50 to the reinforcement layer 46 is ensured appropriately, and exposure of the reinforcement layer 46 is prevented. From this viewpoint, in the tire 2, the depth DG of the main groove 50 is appropriately adjusted in consideration of the thickness of the tread 4 so that the thickness TG can be secured to 1.3 mm or more. Since the depth DG of the main groove 50 is determined in consideration of the thickness TG, a preferable upper limit of the depth DG of the main groove 50 is not set.

  In the tire 2, the width WG of the main groove 50 is equal to the depth DG of the main groove 50, or the width WG of the main groove 50 is larger than the depth DG of the main groove 50. In the tire 2, even when the tread 4 having a small thickness TT is employed, the main groove 50 effectively contributes to drainage. In the tire 2, further improvement in high-speed durability is achieved while maintaining good drainage. From this point of view, the width WG of the main groove 50 is preferably larger than the depth DG of the main groove 50. More specifically, the ratio of the width WG to the depth DG is more preferably 1.1 or more, and further preferably 1.2 or more. From the viewpoint of suppressing the influence of the main groove 50 on the ground contact area, this ratio is preferably 2.0 or less, and more preferably 1.8 or less.

  In the tire 2, a wear indicator 60 (hereinafter referred to as an indicator) is provided in the main groove 50. A single main groove 50 is usually provided with a plurality of indicators 60. These indicators 60 are arranged at intervals in the circumferential direction. This interval is appropriately determined according to the specifications of the tire 2.

  The indicator 60 protrudes radially outward from the bottom 54 of the main groove 50. In other words, the indicator 60 is formed by raising a part of the bottom 54 of the main groove 50. As is apparent from FIG. 4, the indicator 60 bridges one side wall 56 of the main groove 50 and the other side wall 56. In the tire 2, the top surface 62 of the indicator 60 is flat. The top surface 62 is substantially parallel to the bottom 54 of the main groove 50. The top surface 62 and the side wall 56 form a corner 64. In other words, there is a corner 64 between the top surface 62 and the side wall 56. As is apparent from FIG. 4, the corner 64 between the top surface 62 and the side wall 56, that is, the corner 64 of the indicator 60 is rounded. In FIG. 4, the arrow Rb is the radius of curvature of the corner 64. In the tire 2, the radius of curvature Rb of the arc representing the corner 64 is 1 mm or more and 4 mm or less.

  In FIG. 4, a double arrow HW is the height of the indicator 60. This height HW is represented by the height from the bottom 54 of the main groove 50 to the top surface 62 of the indicator 60. When the bottom 54 of the main groove 50 is not flat, the height HW is represented by the maximum height.

  As described above, the tread 4 is made of a crosslinked rubber. The tread 4 is worn by use. Wear results in a shallow main groove 50. The shallow main groove 50 affects drainage. If drainage is reduced, hydroplaning may occur.

  In the tire 2, the top surface 62 of the indicator 60 is located radially inward of the tread surface 24. When the tread 4 is worn, the top surface 62 of the indicator 60 is eventually exposed on the surface of the tire 2. In the tire 2, the height HW of the indicator 60 is adjusted to the depth of the groove 48, specifically the main groove 50, which may reduce drainage as the wear further proceeds. The driver can grasp the degree of wear by checking the degree of exposure of the wear indicator 60. In the normal tire 2, the height HW is set in a range of 1.5 mm to 2.0 mm. In the tire 2, the height HW of the indicator 60 is 1.7 mm.

  In the tire 2, the indicator 60 is provided with a thin-film connection 66. In detail, the indicator 60 of the tire 2 is provided with four tethers 66. As is apparent from FIG. 4, these linkages 66 are located on the radially outer side of the indicator 60. Each tether 66 is connected to the indicator 60 and the side wall 56 of the main groove 50.

  The tether 66 includes an edge 68 that spans between the side wall 56 and the indicator 60. The contour of the edge 68 has an inwardly convex shape in the radial direction. In the tire 2, the outline of the edge 68 is an arc.

  In the tire 2, a plurality of linkages 66 are provided in the indicator 60. In the tire 2 shown in FIG. 1-4, four linkages 66 are provided for one indicator 60. Of these linkages 66, two linkages 66 a are connected to the indicator 60. Furthermore, the two tethers 66a are also connected to a side wall 56a (hereinafter referred to as a first side wall) located on the first end TE1 side of the tread surface 24. The remaining two linkages 66 b are connected to the indicator 60. Further, the remaining two linkages 66b are also connected to a side wall 56b (hereinafter referred to as a second side wall) located on the second end TE2 side of the tread surface 24. In the present invention, the connection 66a positioned on the first side wall 56a side is referred to as a first connection, and the connection 66b positioned on the second side wall 56b is referred to as a second connection.

  In the tire 2, the plurality of linkages 66 provided in one indicator 60 includes a plurality of first linkages 66a and a plurality of second linkages 66b. As shown in FIG. 3, these first nails 66 a are arranged at intervals in the circumferential direction. These second nails 66b are arranged at intervals in the circumferential direction. The number of first nails 66 a and the number of second nails 66 b provided in one indicator 60 is appropriately determined according to the size of the indicator 60 provided in the tire 2.

  In FIG. 3, a double-headed arrow D1 represents a distance between one first link 66a and another first link 66a positioned next to the one first link 66a in the circumferential direction. In the tire 2, the distance D1 is preferably 2 mm or more from the viewpoint of easy formation of the first nails 66a. Since the distance D1 is determined by the size of the indicator 60 and the number of first nails 66a provided in the indicator 60, a preferable upper limit of the distance D1 is not particularly set.

  In FIG. 3, a double-headed arrow D2 represents a distance between one second joint 66b and another second joint 66b positioned next to the one second joint 66b in the circumferential direction. In the tire 2, the distance D2 is preferably 2 mm or more from the viewpoint of easy formation of the second nails 66b. Note that the distance D2 is determined by the size of the indicator 60 and the number of second nails 66b provided in the indicator 60. Therefore, a preferable upper limit of the distance D2 is not particularly set.

  In FIG. 4, the symbol P1a is a boundary between the edge 68 of the first joint 66a and the first side wall 56a. Reference symbol P1b is a boundary between the edge 68 of the first joint 66a and the top surface 62 of the indicator 60.

  In the tire 2, the edge 68 of the first nail 66a is in contact with the first side wall 56a at the boundary P1a. The edge 68 of the first joint 66a is in contact with the top surface 62 of the indicator 60 at the boundary P1b. The center position of the arc representing the contour of the edge 68 of the first link 66a is such that the edge 68 of the first link 66a contacts the first side wall 56a at the boundary P1a and contacts the top surface 62 of the indicator 60 at the boundary P1b. Is set.

  In FIG. 4, the symbol P2a is a boundary between the edge 68 of the second joint 66b and the second side wall 56b. Reference symbol P <b> 2 b is a boundary between the edge 68 of the second joint 66 b and the top surface 62 of the indicator 60.

  In the tire 2, the edge 68 of the second tie 66b is in contact with the second side wall 56b at the boundary P2a. The edge 68 of the second joint 66b is in contact with the top surface 62 of the indicator 60 at the boundary P2b. The center position of the arc representing the contour of the edge 68 of the second link 66b is such that the edge 68 of the second link 66b contacts the second side wall 56b at the boundary P2a and contacts the top surface 62 of the indicator 60 at the boundary P2b. Is set.

  In the present invention, unless otherwise specified, the dimensions and angles of the respective members of the tire 2 are measured in a state where the tire 2 is incorporated in a regular rim and the tire 2 is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire 2. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 depends. “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 2 relies. “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. In the case of the passenger car tire 2, the dimensions and angles are measured in a state where the internal pressure is 180 kPa.

  The tire 2 described above is manufactured as follows. In manufacturing the tire 2, a plurality of rubber members such as the inner liner 18, the carcass 12, and the beads 10 are assembled to prepare a raw cover (unvulcanized tire 2). This raw cover is put into a mold. The mold has a toroidal cavity surface. This cavity surface forms the outer surface of the tire 2. The outer surface of the raw cover is in contact with the cavity surface. The inner surface of the raw cover contacts the bladder or the core. The raw cover is pressurized and heated in the mold. The rubber composition of the raw cover flows by pressurization and heating. The rubber causes a crosslinking reaction by heating, and the tire 2 is obtained. The manufacturing method of the tire 2 includes (1) a step of preparing a raw cover, (2) a step of putting the raw cover into a mold, and (3) a step of pressurizing and heating the raw cover in the mold.

  FIG. 5 shows a part of the cavity surface 72 of the mold 70 used for manufacturing the tire 2. In FIG. 5, the vertical direction corresponds to the circumferential direction of the tire 2, the horizontal direction corresponds to the axial direction of the tire 2, and the direction perpendicular to the paper surface corresponds to the radial direction of the tire 2. The part of the mold 70 shown in FIG. 5 forms the part of the indicator 60 shown in FIG. 5 corresponds to the inside in the radial direction of the tire 2, and the back side of this paper corresponds to the outside in the radial direction of the tire 2.

  FIG. 6 shows a cross section of the mold 70 taken along the line VI-VI in FIG. FIG. 7 shows a cross section of the mold 70 taken along the line VII-VII in FIG. In FIG. 6, the vertical direction corresponds to the radial direction of the tire 2, the horizontal direction corresponds to the axial direction of the tire 2, and the direction perpendicular to the paper surface corresponds to the circumferential direction of the tire 2. In FIG. 7, the vertical direction corresponds to the circumferential direction of the tire 2, the horizontal direction corresponds to the radial direction of the tire 2, and the direction perpendicular to the paper surface corresponds to the axial direction of the tire 2.

  In this mold 70, the cavity surface 72 includes a protrusion 74. The protrusion 74 extends in the circumferential direction. The protrusion 74 protrudes inward in the radial direction. The ridge 74 includes a top surface 76 and a pair of side surfaces 78. Each side surface 78 extends from the top surface 76 substantially outward in the radial direction. Specifically, the side surface 78 is inclined with respect to the radial direction. The absolute value of the inclination angle of the side surface 78 (angle α1 and angle α2 shown in FIG. 6) is normally set in the range of 5 ° to 25 °. In the mold 70, the top surface 76 and the side surface 78 form a corner 80. As apparent from FIG. 6, the corner 80 between the top surface 76 and the side surface 78, that is, the corner 80 of the protrusion 74 is rounded. The protrusion 74 forms the main groove 50 of the tire 2. The top surface 76 forms the bottom 54 of the main groove 50. The side surface 78 forms the side wall 56 of the main groove 50.

  The protrusion 74 further includes a main recess 82. The main recess 82 is recessed radially outward from the top surface 76 of the protrusion 74. The main recess 82 includes a bottom 84 and a pair of inclined surfaces 86. Each inclined surface 86 extends from the bottom 84 toward the top surface 76 of the ridge 74. The slope 86 is inclined with respect to the radial direction. The absolute value of the inclination angle of the slope 86 (angle β1 and angle β2 shown in FIG. 7) is normally set in the range of 50 ° to 70 °. The bottom 84 of the main recess 82 and the side surface 78 of the ridge 74 form a corner 88. As is apparent from FIG. 6, the corner 88 between the bottom 84 of the recess 82 and the side surface 78 of the protrusion 74, that is, the corner 88 of the main recess 82 is rounded. In this mold 70, the main recess 82 forms the indicator 60 of the tire 2.

  The main recess 82 further includes a sub-recess 90. The sub-recess 90 is recessed further outward in the radial direction from the bottom 84 of the main recess 82. This sub-recess 90 forms the tether 66 of the indicator 60. The sub-recess 90 has a bottom 92 for forming the edge 68 of the tether 66. As described above, the outline of the edge 68 of the joint 66 is represented by an arc. Therefore, the bottom 92 of the sub-recess 90 is also represented by an arc.

  As described above, in the manufacture of the tire 2, the raw cover is put into the mold 70 and is pressurized and heated in the mold 70. At this time, the cavity surface 72 of the mold 70 contacts the raw cover. The protrusions 74 on the cavity surface 72 sink into the raw cover.

  In the manufacture of the tire 2, when the protrusion 74 is fitted into the raw cover, the top surface 76 of the protrusion 74 comes into contact with the raw cover. In the conventional mold, the main recess of the ridge is blocked by the raw cover by this contact. However, in the mold 70 of the present invention, as described above, the main recess 82 includes the sub-recess 90. The sub-recess 90 is located at a corner 88 formed by the bottom 84 of the main recess 82 and the side surface 78 of the protrusion 74. In other words, the sub-recess 90 is located at a corner 88 between the bottom 84 of the main recess 82 and the side surface 78 of the ridge 74. The sub-recess 90 is located closer to the outside of the mold 70 than the main recess 82. For this reason, the timing at which the space between the main recess 82 and the raw cover is sealed is slightly delayed as compared with the conventional mold. Air in the space is discharged to the outside of the mold 70 through the sub-recess 90. In the mold 70, the air in the space is sufficiently replaced with rubber. In this mold 70, the rubber flow failure due to the remaining air is suppressed. As described above, the sub-recess 90 forms the connection 66 of the indicator 60. That is, the connection 66 of the tire 2 contributes to air discharge. In the tire 2, the remaining of air is suppressed. Since the rubber flow failure due to the remaining air is suppressed, the occurrence of bear due to the rubber flow failure is effectively suppressed. According to the present invention, the pneumatic tire 2 in which the generation of bears is suppressed can be obtained.

  As described above, in the tire 2, the depth DG of the main groove 50 is 6 mm or more. The width WG of the main groove 50 is equal to the depth DG of the main groove 50, or the width WG of the main groove 50 is larger than the depth DG of the main groove 50. Moreover, the ratio of the width WG of the main groove 50 to the width WT of the tread surface 24 is 6% or more. The main groove 50 of the tire 2 has a width WG larger than the width of the main groove of the conventional tire. The main groove 50 having a large width WG invites a large indicator 60. For this reason, in the mold 70 of the tire 2, the main recess 82 for the indicator 60 is larger than that of the conventional tire mold. The large main recess 82 adversely affects the discharge of air. However, as described above, the mold 70 is further provided with the sub-recess 90 in the main recess 82. For this reason, although the large width WG is adopted for the main groove 50, the air is sufficiently discharged. In the tire 2, the remaining of air is suppressed. Since the rubber flow failure due to the remaining air is suppressed, the occurrence of bear due to the rubber flow failure is effectively suppressed. The tether 66 of the present invention functions more effectively in the tire 2 in which the main groove 50 has a large width WG. Even if a large width WG is adopted for the main groove 50, the generation of bears can be suppressed, so that the tread 4 having a small thickness can be adopted, and the high-speed durability can be further improved.

  As described above, in the tire 2, the connection 66 effectively suppresses the generation of bears. For this reason, it is not necessary to provide discharge means such as a vent hole in the mold 70 for manufacturing the tire 2 in order to prevent bears. Since it is not necessary to provide such discharge means, the tire 2 can be obtained without spew formation, and maintenance of the discharge means is not required in cleaning the mold 70. The tire 2 also contributes to improvement of productivity.

  In the tire 2, the contour of the edge 68 of the joint 66 is not particularly limited. However, like the tire 2, the joint 66 having the edge 68 whose contour is represented by an arc is stably formed and contributes to effective guidance of air to the outside of the mold 70. From this point of view, the outline of the edge 68 of the link 66 is preferably represented by an arc.

  As described above, in the tire 2, the link 66 is connected to the indicator 60 and the side wall 56 of the main groove 50. This tether 66 restrains the movement of the side wall 56. In the tire 2 in the traveling state, the connection 66 suppresses the change in the shape of the main groove 50. In the tire 2, since the fluctuation in drainage is small, good drainage is stably maintained. Since changes in the shape of the ground plane can be suppressed, fluctuations in performance such as steering stability are small. In the tire 2, performance such as steering stability is good and stably maintained.

  As described above, the tire 2 is configured to be attached to the vehicle such that the first end TE1 of the tread surface 24 is located inside the vehicle. A force tends to easily act on the tread 4 of the tire 2 in a direction from the first end TE1 of the tread surface 24 toward the second end TE2. From the viewpoint of stably forming the ground contact surface and maintaining good and stable performance such as steering stability, the number of the second nails 66b provided on the second end TE2 side is on the first end TE1 side. The number is preferably larger than the number of first nails 66a provided. More specifically, the difference between the number of the second nails 66b and the number of the first nails 66a is preferably 1 or more, and more preferably 2 or more. This difference is preferably 5 or less, more preferably 4 or less, from the viewpoint of easy formation of the connection 66. FIG. 8 shows a wear indicator 94 in which the number of first nails 66a is 1 and the number of second nails 66b is 2 as another mode of the indicator 60.

  In FIG. 3, the double-headed arrow T1 represents the thickness of the first joint 66a. A double-headed arrow T2 represents the thickness of the second tie 66b.

  In the tire 2, the thickness T1 is preferably 0.3 mm or greater and 1.2 mm or less. By setting the thickness T1 to be equal to or greater than 0.3 mm, the first nails 66a effectively contribute to air discharge and restraint of the first side wall 56a. In this respect, the thickness T1 is more preferably equal to or greater than 0.4 mm. By setting the thickness T1 to be equal to or less than 1.2 mm, the first nails 66a can be formed without being applied, and the influence of the first nails 66a on the mass can be suppressed. In this respect, the thickness T1 is more preferably 1.1 mm or less.

  In the tire 2, the thickness T2 is preferably 0.3 mm or greater and 1.2 mm or less. By setting the thickness T2 to be 0.3 mm or more, the second joint 66b effectively contributes to the discharge of air and the restraint of the second side wall 56b. In this respect, the thickness T2 is more preferably equal to or greater than 0.4 mm. By setting the thickness T2 to be equal to or less than 1.2 mm, the second binder 66b can be formed without being applied, and the influence of the second binder 66b on the mass can be suppressed. In this respect, the thickness T2 is more preferably 1.1 mm or less.

  In FIG. 4, an arrow Rc1 is the radius of curvature of the arc representing the contour of the edge 68 of the first link 66a. The arrow Rc2 is the radius of curvature of the arc representing the contour of the edge 68 of the second link 66b.

  In the tire 2, the curvature radius Rc1 is preferably 4 mm or more. Thereby, the 1st tie 66a contributes effectively to discharge | emission of air and restraint of the 1st side wall 56a. In this respect, the curvature radius Rc1 is more preferably 5 mm or more. A large curvature radius Rc1 invites a large first nail 66a. With the large first nail 66a, the sub-recess 90 cannot be sufficiently filled with rubber, and there is a possibility that the hook will occur, and this first nail 66a affects the mass. In this respect, the curvature radius Rc1 is preferably 10 mm or less, and more preferably 9 mm or less.

  In the tire 2, the radius of curvature Rc2 is preferably 4 mm or more. Thereby, the second tie 66b effectively contributes to the discharge of air and the restraint of the second side wall 56b. In this respect, the curvature radius Rc2 is more preferably 5 mm or more. The large curvature radius Rc2 invites a large second joint 66b. In the large second tie 66b, the sub-recess 90 cannot be sufficiently filled with rubber, and there is a possibility that the hook is generated, and the second tie 66b affects the mass. In this respect, the curvature radius Rc2 is preferably 10 mm or less, and more preferably 9 mm or less.

  As described above, in the manufacture of the tire 2, a plurality of rubber members are assembled, and a raw cover (unvulcanized tire 2) is prepared. In the raw cover preparation step, the tread 4 as a rubber member may be formed by extruding the rubber composition. In this case, the shape of the mouth of the extruder is made to correspond to the cross-sectional shape of the tread 4. Although not shown, the cross-sectional shape of the tread 4 formed by extrusion is provided with a recess corresponding to the main groove 50. The width of the bottom of the recess is set equal to or less than the width of the bottom 54 of the main groove 50. As shown in FIG. 4, the bottom 54 of the main groove 50 is substantially flat. For this reason, it is normal that the bottom of this recessed part is also finished flat.

  As described above, according to the present invention, the formation of the bear is effectively suppressed by providing the connection 66 on the tire 2. A projection having a height of 0.3 to 0.6 mm may be provided on the bottom of the concave portion from the viewpoint of further promoting the discharge of air and more effectively suppressing the generation of the bear. Furthermore, the cross-sectional shape of this protrusion may be a triangle. Thereby, since the rubber flow failure due to the remaining air is further suppressed, the occurrence of bear due to this rubber flow failure is further effectively suppressed.

  FIG. 9 shows a part of a pneumatic tire 102 according to another embodiment of the present invention. FIG. 9 corresponds to FIG. 4 described above. In FIG. 9, the vertical direction is the radial direction of the tire 102, the horizontal direction is the axial direction of the tire 102, and the direction perpendicular to the paper surface is the circumferential direction of the tire 102.

  The tire 102 has the same configuration as that of the tire 2 shown in FIG. 1 except for the connection described later. For this reason, in this FIG. 9, the same code | symbol is attached | subjected to the member same as the member of the tire 2 of FIG. 1, and the detailed description is abbreviate | omitted.

  The indicator 60 of the tire 102 is provided with a thin-film connection 104 as in the tire 2 shown in FIG. The connection 104 connects the side wall 56 of the main groove 50 and the indicator 60. The connection 104 includes an edge 106 that bridges between the side wall 56 and the indicator 60. The contour of the edge 106 has an inwardly convex shape in the radial direction. As is clear from FIG. 9, the contour of the side wall 56 and the top surface 62 of the indicator 60 is a straight line. The side wall 56 and the top surface 62 are constituted by planes. The main groove 50 includes the side wall 56 and the bottom 54. There is a corner 58 between the side wall 56 and the bottom 54. The contour of the corner 58 is an arc, and the radius of curvature Ra of the arc is 1 mm or greater and 4 mm or less. Further, there is a corner 64 between the side wall 56 and the top surface 62, and the contour of the corner 64 is an arc. The radius of curvature Rb of this arc is 1 mm or greater and 4 mm or less.

  In the tire 102, the edge 106 of the joint 104 includes two flat surfaces 108. In other words, the contour of the edge 106 of the joint 104 includes two straight lines corresponding to the two planes 108, respectively. These flat surfaces 108 are inclined with respect to the side wall 56 or the top surface 62. The angle formed by one plane 108 p (hereinafter referred to as the first plane) near the side wall 56 with respect to the side wall 56 is smaller than the angle formed by the other plane 108 q (hereinafter referred to as the second plane) with respect to the side wall 56. Alternatively, the angle formed by the first plane 108p with respect to the top surface 62 is larger than the angle formed by the second plane 108q with respect to the top surface 62.

  In the tire 102, the first plane 108p and the second plane 108q are directly connected. A portion between the first plane 108p and the second plane 108q may be rounded. Another plane may be provided between the first plane 108p and the second plane 108q. In the tire 102, the side wall 56 and the first plane 108p are directly connected. In the tire 102, the space between the side wall 56 and the first plane 108p may be rounded, or another plane may be provided between the side wall 56 and the first plane 108p. In the tire 102, the second flat surface 108q and the top surface 62 are directly connected. The space between the second plane 108q and the top surface 62 may be rounded, or another plane may be provided between the second plane 108q and the top surface 62.

  Although not shown, this tire 102 is also manufactured using a mold in the same manner as the tire 2 shown in FIG. This mold has the same configuration as the mold 70 shown in FIG. 6 except for the bottom of the sub-dent corresponding to the edge 106 of the joint 104. Although not specifically shown and described, the bottom of the sub-indent includes two planes corresponding to the two planes 108 included in the edge 106 of the tether 104, in other words, the contour of the bottom of the sub-indent. Corresponds to the contour of the edge 106 of the tether 104.

  In the tire 102 as well, as in the tire 2 shown in FIG. 1, the joint 104 that connects the wear indicator 60 and the side wall 56 of the main groove 50 contributes to the discharge of air. In the tire 102, residual air is suppressed. Since the rubber flow failure due to the remaining air is suppressed, the occurrence of bear due to the rubber flow failure is effectively suppressed. Since the edge 106 of the tether 104 includes two planes 108, the machining of the mold for the tire 102 compared to the mold 70 for the tire 2 where the edge 68 of the tether 66 is represented by an arc. Is even easier. This effect is particularly remarkable when the mold is processed by hand carving. Since the connection 104 restrains the movement of the side wall 56, the connection 104 suppresses a change in the shape of the main groove 50 in the tire 102 in the traveling state. In the tire 102, since the fluctuation in drainage is small, good drainage is stably maintained. Since changes in the shape of the ground plane can be suppressed, fluctuations in performance such as steering stability are small. In the tire 102, performance such as steering stability is good and stable.

  In FIG. 9, symbol PA is a boundary between the side wall 56 and the first plane 108p. When a rounded surface or the like is provided between the side wall 56 and the first plane 108p, the position where the extension line of the first plane 108p intersects the side wall 56 (or the extension line of the side wall 56) is the boundary PA. Identified as The symbol PB is a boundary between the second plane 108q and the top surface 62. When a rounded surface or the like is provided between the second plane 108q and the top surface 62, a position where an extension line of the second plane 108q intersects the top surface 62 (or an extension line of the top surface 62). Is identified as the boundary PB. The solid line LAB is an imaginary straight line that extends with an inclination with respect to the side wall 56 or the top surface 62. The straight line LAB passes through the boundary PA and the boundary PB. In this paragraph, the boundary PA and the boundary PB and the straight line LAB have been described based on the bridge 104b that bridges one side wall 56b and the indicator 60. However, the bridge 104a that bridges the other side wall 56a and the indicator 60. Similarly, the boundary PA and the boundary PB and the straight line LAB are specified.

  In FIG. 9, a double-headed arrow HH is a radial distance from the top surface 62 to the tread surface 24. A double arrow HA is a radial distance from the top surface 62 to the boundary PA.

  In the tire 2, the ratio of the distance HA to the distance HH is preferably 0.4 or more and 0.6 or less. By setting this ratio to 0.4 or more, the link 104 effectively contributes to the discharge of air. Since this connection 104 restrains the side wall 56, the shape change of the main groove 50 is suppressed. In addition, the connection 104 can be easily processed. In this respect, the ratio is more preferably 0.45 or more. By setting this ratio to 0.6 or less, the size of the link 104 is appropriately maintained. Since the sub-recess for the connection 104 is sufficiently filled with rubber, the connection 104 is less likely to be chipped. In this respect, the ratio is more preferably equal to or less than 0.55. Particularly preferably, this ratio is 0.50.

  In FIG. 9, the symbol PT is a position where the top surface 62 intersects the main groove 50. Specifically, it is a position where an extended line of a straight line representing the outline of the top surface 62 intersects a line representing the outline of the main groove 50. A double-headed arrow WW is an axial distance from one position PT to the other position PT2. This distance WW is also the length of the top surface 62. A double arrow WB is an axial distance from the position PT to the boundary PB.

  In the tire 2, the ratio of the distance WB to the distance WW is preferably 0.1 or more and 0.4 or less. By setting this ratio to 0.1 or more, the link 104 effectively contributes to the discharge of air. Since this connection 104 restrains the side wall 56, the shape change of the main groove 50 is suppressed. In addition, the connection 104 can be easily processed. In this respect, the ratio is more preferably equal to or greater than 0.20. By setting this ratio to 0.4 or less, the size of the link 104 is appropriately maintained. Since the sub-recess for the connection 104 is sufficiently filled with rubber, the connection 104 is less likely to be chipped. In this respect, the ratio is preferably equal to or less than 0.30. Particularly preferably, this ratio is 0.25.

  In FIG. 9, the angle γ is an angle formed by the straight line LAB with respect to the side wall 56. The angle γa is an angle formed by the first plane 108p with respect to the side wall 56.

  In the tire 2, the ratio of the angle γa to the angle γ is preferably 0.4 or more and 0.6 or less. By setting this ratio to 0.4 or more, the link 104 effectively contributes to the discharge of air. Since this connection 104 restrains the side wall 56, the shape change of the main groove 50 is suppressed. In addition, the connection 104 can be easily processed. In this respect, the ratio is more preferably 0.45 or more. By setting this ratio to 0.6 or less, the size of the link 104 is appropriately maintained. Since the sub-recess for the connection 104 is sufficiently filled with rubber, the connection 104 is less likely to be chipped. In this respect, the ratio is more preferably equal to or less than 0.55. Particularly preferably, this ratio is 0.50.

  In FIG. 9, the angle η is an angle formed by the straight line LAB with respect to the top surface 62. The angle ηa is an angle formed by the second plane 108q with respect to the top surface 62.

  In the tire 2, the ratio of the angle ηa to the angle η is preferably 0.4 or more and 0.6 or less. By setting this ratio to 0.4 or more, the link 104 effectively contributes to the discharge of air. Since this connection 104 restrains the side wall 56, the shape change of the main groove 50 is suppressed. In addition, the connection 104 can be easily processed. In this respect, the ratio is more preferably 0.45 or more. By setting this ratio to 0.6 or less, the size of the link 104 is appropriately maintained. Since the sub-recess for the connection 104 is sufficiently filled with rubber, the connection 104 is less likely to be chipped. In this respect, the ratio is more preferably equal to or less than 0.55. Particularly preferably, this ratio is 0.50.

  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]
The tire shown in FIGS. 1-4 was manufactured. The size of this tire is 225 / 45ZR17. In Example 1, nine wear indicators were formed for one main groove. Each wear indicator was provided with first and second nails. This is represented by “SC” in the column of discharging means in Table 1 below. The specifications of the first and second nails are shown in Table 1.

[Comparative Example 1]
Comparative Example 1 is a conventional tire. In this comparative example 1, no connection is provided. This is indicated by “-” in the column of discharging means in Table 1 below.

[Comparative Example 2]
A tire of Comparative Example 2 was obtained in the same manner as in Example 1 except that a vent hole was provided in a portion of the mold corresponding to the wear indicator without providing a joint. The adoption of a vent hole as the discharging means is indicated by “VP” in the column of discharging means in Table 1 below.

[Comparative Example 3]
A tire of Comparative Example 3 was obtained in the same manner as in Example 1 except that a recess was provided in the wear indicator without providing a tie. The fact that the concave portion is adopted as the discharging means is represented by “recessed portion” in the column of the discharging means in Table 1 below.

[Comparative Example 4]
A tire of Comparative Example 4 was obtained in the same manner as in Example 1 except that a protrusion was provided on the wear indicator without providing a joint. This convex portion is not connected to the side wall of the main groove as in the connection of the first embodiment. In Comparative Example 4, the fact that the convex portion is adopted as the discharging means is represented by “convex portion” in the column of discharging means in Table 1 below.

[Example 2-6]
Example 1 except that the radius of curvature Rc1 of the arc representing the contour of the first edge and the radius of curvature Rc2 of the arc representing the contour of the second edge are as shown in Table 2 below. The tire of Example 2-6 was obtained.

[Example 7-10]
Tires of Examples 7-10 were obtained in the same manner as in Example 1, except that the thickness of the first joint T1 and the thickness of the second joint T2 were as shown in Table 3 below.

[Examples 11-14]
Tires of Examples 11-14 were obtained in the same manner as in Example 1 except that the number of first nails and the number of second nails were as shown in Table 4 below.

[Bear and spew generation]
The appearance of the trial tires (10 tires) was visually observed to confirm the occurrence of bears and spews in the wear indicator. For bears, the ratio of the number of wear indicators in which the occurrence of bears was confirmed to the total number of wear indicators was calculated as the defect rate. For spews, the presence or absence of occurrence was confirmed. These results are shown in Tables 1-4 below. Regarding the defect rate, the smaller the value, the better the generation of bears is preferable. As for the spew, “G” indicates that no spew has occurred, and “NG” indicates that this spew has occurred.

[Drainage]
A prototype tire was incorporated into a regular rim, and the tire was filled with air so that the internal pressure was 230 kPa. This tire was mounted on an inside drum tester, and a running test was conducted on an asphalt wet road surface with a load of 5 kN, a slip angle of 1 °, and a water depth of 5 mm. The rate of occurrence of hydroplaning was measured. The results are shown in Tables 1-4 below as indices. The larger the value, the better the drainage and the better.

[Steering stability]
A prototype tire was assembled in a regular rim, and the tire was filled with air so that the internal pressure was 230 kPa. This tire was mounted on a passenger car having a displacement of 4300 cc. The driver was driven on the racing circuit to evaluate the driving stability. The results are shown in Tables 1 and 4 below as indices. Larger numbers are preferable. In this evaluation, the prototype tire is attached to the passenger car so that the first end TE1 of the tread surface is located inside the passenger car. Accordingly, the first nails of the respective wear indicators are located on the inner side in the width direction of the passenger car, and the second nails are located on the outer side in the width direction of the passenger car.

  As shown in Table 1-4, 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 wear indicator linkage described above can also be applied to tires for various vehicles.

2 ... Tire 4 ... Tread 6 ... Sidewall 8 ... Clinch 10 ... Bead 12 ... Carcass 14 ... Belt 16 ... Band 24 ... Tread surface 46 ... -Reinforcing layer 48 ... Groove 50 ... Main groove 52 ... Edge of main groove 54 ... Bottom of main groove 56, 56a, 56b ... Side wall of main groove 60 ... Wear indicator 62- ··· Wear indicator top surface 64 ··· Wear indicator corners 66, 66a, 66b · · · Connection 68 · · · Edge of connection 70 · · · Mold 72 · · · Cavity surface 74 · · · Projection 76 · · · ..Top surface 78 ... Side side surface 82 ... Main depression 84 ... Bottom 88 ... Main depression corner 90 ... Sub depression 92 ... Bottom 94 ... As another aspect Wear indicator 102 ... Tire 10 , 104a, 104b ... tie 106 ... edge 108,108p, 108q ··· plane

Claims (10)

It has a tread whose outer surface forms a tread surface,
The tread has carved main grooves extending in the circumferential direction,
The depth of the main groove is 6 mm or more,
The width of the main groove is equal to the depth of the main groove, or the width of the main groove is larger than the depth of the main groove,
The ratio of the width of the main groove to the width of the tread surface is 6% or more,
A wear indicator is provided in the main groove, and the wear indicator protrudes radially outward from the bottom of the main groove.
The wear indicator is provided with a thin-film joint, the joint is located radially outside the wear indicator, and the joint is connected to the wear indicator and the side wall of the main groove. tire. The tether has an edge that spans between the wear indicator and the side wall;
The outline of the edge is an arc,
The pneumatic tire according to claim 1, wherein a radius of curvature of the arc is 4 mm or more.   The pneumatic tire according to claim 1 or 2, wherein a thickness of the connection is 0.3 mm or more and 1.2 mm or less.   The pneumatic according to any one of claims 1 to 3, wherein a plurality of the linkages are provided in the wear indicator, and the linkages are arranged at intervals in the circumferential direction, and the intervals are 2 mm or more. tire.   The plurality of linkages include a first linkage connecting the wear indicator and one side wall of the main groove, and a second linkage connecting the wear indicator and the other side wall of the main groove. The pneumatic tire according to claim 4.   When the tire is configured to be mounted on the vehicle so that one end of the tread surface is located inside the vehicle, the number of the second nails is larger than the number of the first nails. The pneumatic tire according to claim 5. It further includes a reinforcing layer on the inner side in the radial direction of the tread,
The pneumatic tire according to any one of claims 1 to 6, wherein a thickness from the bottom of the main groove to the reinforcing layer is 1.3 mm or more. The tether has an edge that spans between the wear indicator and the side wall;
The edge comprises two planes, which are inclined with respect to the side wall;
The pneumatic tire according to claim 1, wherein an angle formed by one plane close to the side wall with respect to the side wall is smaller than an angle formed by the other plane with respect to the side wall. It has a toroidal cavity surface,
The cavity surface has a protrusion extending in the circumferential direction,
The ridge has a main recess recessed from its top surface,
The main recess has a sub-recess further recessed from the bottom,
A corner is formed by the bottom of the main depression and the side surface of the protrusion,
The mold for manufacturing a pneumatic tire, wherein the sub-dent is located at the corner. Preparing the raw cover;
Introducing the raw cover into a mold;
And pressurizing and heating the raw cover in the mold,
The mold has a toroidal cavity surface,
The cavity surface has a protrusion extending in the circumferential direction,
The ridge has a main recess recessed from its top surface,
The main recess has a sub-recess further recessed from the bottom,
A corner is formed by the bottom of the main depression and the side surface of the protrusion,
The method for manufacturing a pneumatic tire, wherein the sub-dent is located at the corner.

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