JP2010143257A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire which is excellent in riding comfort, productivity, and durability. <P>SOLUTION: Each side part includes a large number of protrusion strips 46 on its inner surface 38a. The inner surface 38a has a buttress area 40 positioned on the outside in a radial direction, and a bead area 42 positioned on the inside in the radial direction. The buttress area 40 or the bead area 42 is a high density area. The occupancy of the protrusion strips 46 in the high density area is not less than 20%. Preferably, in the high density area, the ratio of the distance between the protrusion strip 46 and another protrusion strip 46 positioned next to the protrusion strip 46 to the height of the protrusion strip 46 is 2.5 to 4.5. Preferably, the height of the protrusion strip 46 positioned in the high density area is 0.3 to 3 mm. The width of the protrusion strip 46 is 1 to 4 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire.

  When a tire climbs over a protrusion on the road surface such as a cat's eye, a portion of the tire sidewall may be sandwiched between the flange of the rim and the protrusion and compressed. This compression leads to the cutting of the cords contained in the carcass. The damage accompanied by the cutting of the cord is called a pinch cut. This pinch cut hinders the durability of the tire. An example of a tire that can suppress this pinch cut is disclosed in Japanese Patent Application Laid-Open No. 2007-168540. In this tire, a small rib extending in the circumferential direction is provided on a lumen surface located in the side region.

Japanese Patent Application Laid-Open No. 2007-161070 discloses a pneumatic tire with a noise suppressor in which the adhesion of the noise suppressor is improved while preventing molding defects. A plurality of protrusions are formed on the inner surface of the tire. These ridges are provided by a bladder when the tire is molded. This ridge includes a first ridge that extends through a fixing region to which the noise control device is fixed.
JP 2007-168540 A JP 2007-161070 A

  A ply may be added to the carcass from the viewpoint of suppressing pinch cuts. The addition of this ply can contribute to the rigidity of the carcass. This addition leads to an increase in tire mass and a decrease in ride comfort. This addition of plies also affects material costs and production time. This tire hinders productivity.

  An object of the present invention is to provide a pneumatic tire excellent in durability without impairing riding comfort and productivity.

  The pneumatic tire according to the present invention includes a tread portion and a pair of side portions. Each side portion has a large number of ridges on its inner surface. The inner surface has a buttress area located on the radially outer side and a bead area located on the radially inner side. This buttress area or bead area is a high density area. The occupancy rate of the ridges in this high density region is 20% or more.

  Preferably, in the tire, in the high density region, a ratio of a distance between the ridge and another ridge located adjacent to the ridge to a height of the ridge is 2.5 or more. 4.5 or less.

  Preferably, in this tire, the height of the ridges located in the high density region is not less than 0.3 mm and not more than 3 mm. The width of this ridge is 1 mm or more and 4 mm or less.

  In this tire, the buttress area or the bead area is a high-density area in which the occupying ratio of the ridges is 20%. Even when the tire gets over a protrusion on the road surface such as a cat's eye and is compressed by being sandwiched between the flange of the rim and the protrusion, the impact at the time of compression can be buffered. In this tire, pinch cuts can be suppressed. This tire is excellent in durability. In this tire, since it is not necessary to add a new member for suppressing pinch cuts, productivity can be maintained. Since the rigidity of the tire can be appropriately maintained, the riding comfort is not hindered.

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

  FIG. 1 is a cross-sectional view showing a part of a pneumatic tire 2 according to an embodiment of the present invention. In FIG. 1, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. The tire 2 has a substantially left-right symmetric shape centered on a one-dot chain line CL in FIG. This alternate long and short dash line CL represents the equator plane of the tire 2. The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a belt 12, a band 14, an inner liner 16, and a chafer 18. The tire 2 can be divided into a tread portion T and a pair of side portions S. The tire 2 is a tubeless type. The tire 2 is mounted on a passenger car.

  The tread 4 is made of a crosslinked rubber having excellent wear resistance. The tread 4 has a shape protruding outward in the radial direction. The tread 4 includes a tread surface 20. The tread surface 20 is in contact with the road surface. A groove 22 is carved in the tread surface 20. The groove 22 forms a tread pattern. The groove 22 may not be cut in the tread 4.

  The sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The side wool has a shape protruding outward in the axial direction. The sidewall 6 is made of a crosslinked rubber. The sidewall 6 absorbs an impact from the road surface by bending. Furthermore, the sidewall 6 prevents the carcass 10 from being damaged.

  The bead 8 is located substantially inward of the sidewall 6 in the radial direction. The bead 8 includes a core 24 and an apex 26 that extends radially outward from the core 24. The core 24 has a ring shape. The core 24 includes a plurality of non-stretchable wires (typically steel wires). The apex 26 is tapered outward in the radial direction. The apex 26 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a ply 28. The ply 28 is spanned between the beads 8 on both sides, and extends along the inside of the tread 4 and the sidewall 6. The ply 28 is folded around the core 24 from the inner side to the outer side in the axial direction.

  Although not shown, the ply 28 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 usually 70 ° to 90 °. In other words, the carcass 10 has a radial structure. The cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. A carcass 10 having a bias structure may be employed.

  The belt 12 is located on the radially outer side of the carcass 10. The belt 12 is laminated with the carcass 10. The belt 12 reinforces the carcass 10. The end 30 of the belt 12 is located in the vicinity of the end of the tread 4. The belt 12 includes an inner layer 32 and an outer layer 34. Although not shown, each of the inner layer 32 and the outer layer 34 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 absolute value of the tilt angle is not less than 10 ° and not more than 35 °. The cord inclination direction of the inner layer 32 is opposite to the cord inclination direction of the outer layer 34. A preferred material for the cord is steel. An organic fiber may be used for the cord.

  The band 14 covers the belt 12. In the tire 2, the position of the end 36 of the band 14 coincides with the position of the end 30 of the belt 12 in the axial direction. Although not shown, the band 14 is composed of a cord and a topping rubber. The cord extends substantially in the circumferential direction and is wound spirally. The band 14 has a so-called jointless structure. Since the belt 12 is restrained by this cord, lifting of the belt 12 is suppressed. The cord is usually made of organic fibers. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 16 is joined to the inner peripheral surface of the carcass 10. The inner liner 16 is made of a crosslinked rubber. For the inner liner 16, rubber having excellent air shielding properties is used. The inner liner 16 serves to maintain the internal pressure of the tire 2.

  The chafer 18 is located in the vicinity of the bead 8. When the tire 2 is incorporated into the rim, the chafer 18 comes into contact with the rim. By this contact, the vicinity of the bead 8 is protected. The chafer 18 is usually made of cloth and rubber impregnated in the cloth. A chafer 18 made of a single rubber may be used.

  In FIG. 1, a solid line LM is a straight line passing through the end 30 of the belt 12 and is orthogonal to the inner surface 38 of the tire 2. This solid line LM is the boundary between the tread portion T and the side portion S. In FIG. 1, a point PA is an intersection between the solid line LA and the inner surface 38. The point PA is also an end (outer end) located on the radially outer side of the inner surface 38 of the side portion S. A solid line BBL is a bead base line. This bead base line is a line that defines the rim diameter (see JATMA) of the rim on which the tire 2 is mounted. The solid line L0 is a straight line passing through the point PA and parallel to the bead base line. A double arrow line HA represents the height in the radial direction from the bead base line to the solid line L0. The height HA is the radial height of the inner surface 38a of the side portion S. The double arrow line HB represents the height in the radial direction from the bead base line to the equator plane. This height HB is the tire height. From the viewpoint that the tire 2 can stably exhibit performance, the ratio of the height HA to the height HB is more preferably 60% or more, and particularly preferably 70% or more. This ratio is more preferably 95% or less, and particularly preferably 90% or less.

  In FIG. 1, the solid line L1 is located at a position away from the solid line L0 in the radial direction by a distance corresponding to 20% of the height HA. Point PB is the intersection of this solid line L1 and inner surface 38a. The solid line L2 is located away from the bead base line by a distance corresponding to 55% of the height HA in the radial direction. Point PC is an intersection of this solid line L2 and the inner surface 38a. The solid line L3 is at a position away from the bead base line by a distance corresponding to 10% of the height HA in the radial direction. A point PD is an intersection of the solid line L3 and the inner surface 38a. In the tire 2, a portion from the point PA to the point PB is the buttress region 40 and a portion from the point PC to the point PD is the bead region 42 on the inner surface 38 a. A portion located between the buttress area 40 and the bead area 42 is a boundary area 44. In the tire 2, the inner surface 38 a of the side portion S has a buttress area 40 located on the radially outer side and a bead area 42 located on the radially inner side.

  FIG. 2 is a development view showing a part of the inner surface 38 of the tire 2 of FIG. 1. In FIG. 2, the vertical direction is the radial direction, the horizontal direction is the circumferential direction, and the direction perpendicular to the paper surface is the axial direction. A solid line LA represents the position of the point PA. A solid line LB represents the position of the point PB. A solid line LC represents the position of the point PC. A solid line LD represents the position of the point PD.

  As shown in the figure, in the tire 2, the side portion S further includes a plurality of ridges 46 on the inner surface 38 a. In the tire 2, the ridges 46 are formed by a first ridge 46a positioned on the tread portion T side of the inner surface 38a and an end 48 (inner end) positioned radially inward of the inner surface 38a. It is comprised from the 2nd protruding item | line 46b located in the side, and the 3rd protruding item | line 46c extended toward the outer end from the inner end 48 of this inner surface 38a.

  One end 50a of the first ridge 46a is located on the straight line LA. The first protrusion 46a extends downward from the one end 50a inward in the radial direction. The first ridge 46a is inclined with respect to the circumferential direction. The other end 50 b of the first ridge 46 a is located in the boundary region 44. In the tire 2, the first ridges 46 a are disposed in part of the buttress area 40 and the boundary area 44.

  One end 52a of the second ridge 46b is located on the radially inner side of the other end 50b of the first ridge 46a. The second ridge 46b is separated from the first ridge 46a in the radial direction. The second protrusion 46b extends downward from the one end 52a inward in the radial direction. The second ridge 46b is inclined with respect to the circumferential direction. One end 52 a and the other end 52 b of the second ridge 46 b are located in the bead region 42. In the tire 2, the second ridge 46 b is located in the bead region 42.

  One end 54 of the third ridge 46 c is located at the inner end 48 of the inner surface 38 a of the side portion S. The third ridge 46c extends upward from the one end 54 in the radial direction outward. The third ridge 46c is inclined with respect to the circumferential direction. In the tire 2, the inclination direction of the third protrusion 46c is opposite to the inclination direction of the first protrusion 46a. The inclination direction of the third protrusion 46c is opposite to the inclination direction of the second protrusion 46b. As shown in the drawing, in the tire 2, the third protrusion 46c is disposed on the entire inner surface 38a.

  FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. FIG. 3 shows a cross section of the first ridge 46a. The first ridge 46a protrudes from the inner surface 38a. As shown in the drawing, the first ridge 46a and another first ridge 46a located next to the first ridge 46a are arranged at a predetermined interval. The line III-III in FIG. 2 is orthogonal to the longitudinal direction of the first ridge 46a.

  In the tire 2, the outline of the cross section of the first ridge 46a is an arc. As shown in the drawing, the cross-sectional shape of the first ridge 46a is tapered from the base 56a toward the tip 58a. In the tire 2, the cross section may be shaped like a trapezoid, a semicircle, a triangle, or the like.

  FIG. 4 is an enlarged cross-sectional view taken along line IV-IV in FIG. FIG. 4 shows a cross section of the second ridge 46b. The second ridge 46b protrudes from the inner surface 38a. As shown in the drawing, the second ridge 46b and another second ridge 46b located next to the second ridge 46b are arranged at a predetermined interval. The line IV-IV in FIG. 2 is orthogonal to the longitudinal direction of the second ridge 46b.

  In the tire 2, the contour of the cross section of the second ridge 46b is an arc. As shown in the drawing, the cross-sectional shape of the second ridge 46b has a tapered shape from the base 56b toward the tip 58b. The cross-sectional shape of the second ridge 46b is the same as that of the first ridge 46a. In the tire 2, the cross section may be shaped like a trapezoid, a semicircle, a triangle, or the like.

  FIG. 5 is an enlarged cross-sectional view taken along line VV in FIG. FIG. 5 shows a cross section of the third ridge 46c. The third ridge 46c protrudes from the inner surface 38a. As shown in the figure, the third ridge 46c and another third ridge 46c located next to the third ridge 46c are arranged at a predetermined interval. 2 is orthogonal to the longitudinal direction of the third ridge 46c.

  In the tire 2, the contour of the cross section of the third ridge 46c is an arc. As shown in the drawing, the cross-sectional shape of the third ridge 46c has a tapered shape from the base 56c toward the tip 58c. The cross-sectional shape of the third ridge 46c is the same as that of the first ridge 46a. In the tire 2, the cross section may be shaped like a trapezoid, a semicircle, a triangle, or the like.

  When the tire 2 gets over a protrusion on the road surface such as a cat's eye, the side portion S is sandwiched between the flange of the rim and the protrusion and compressed. Since the side portion S has a shape protruding outward in the axial direction, the side portion S bends at a portion having the maximum width. Due to this bending, on the inner surface 38 a of the side portion S, the portion located in the buttress region 40 and the portion located in the bead region 42 come into contact with each other.

  As described above, in the tire 2, the ridges 46 protrude from the inner surface 38a. The ridge 46 can buffer the impact during compression. In the tire 2, pinch cuts can be suppressed. The tire 2 is excellent in durability.

  In the tire 2, the buttress area 40 is appropriately occupied by a large number of ridges 46. The buttress area 40 is an area where the ridges 46 exist at a high density (a high density area). In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be suppressed. The tire 2 is excellent in durability.

  In the tire 2, the ratio in which the buttress area 40 is occupied by the ridges 46 is larger than the ratio in which the boundary area 44 is occupied by the ridges 46. In the tire 2, the impact during compression can be effectively buffered while suppressing an increase in mass. In the tire 2, pinch cuts can be suppressed. The tire 2 is excellent in durability. In the tire 2, since the rigidity can be appropriately maintained, the riding comfort is not hindered. In the present specification, this ratio is referred to as the occupation ratio of the ridges 46.

  In the tire 2, the bead region 42 is appropriately occupied by a large number of ridges 46. The bead region 42 is a region (high-density region) where the ridges 46 are present at high density. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be suppressed. The tire 2 is excellent in durability.

  In the tire 2, the occupancy rate of the ridges 46 in the bead region 42 is larger than the occupancy rate of the ridges 46 in the boundary region 44. In the tire 2, the impact during compression can be effectively buffered while suppressing an increase in mass. In the tire 2, pinch cuts can be suppressed. The tire 2 is excellent in durability. In the tire 2, since the rigidity can be appropriately maintained, the riding comfort is not hindered.

  The tire 2 is manufactured as follows. First, a rubber member constituting the tire 2 such as a tread 4 and a sidewall 6 is supplied to a former (not shown). Next, in the former, these rubber members are assembled. With this assembly, a low cover (also referred to as an uncrosslinked tire) is obtained. Next, this raw cover is put into the opened mold. When thrown, the bladder is contracted. When thrown, the bladder is positioned inside the raw cover. Next, the bladder expands due to gas filling. Due to this expansion, the raw cover is deformed. This deformation is called shaping. Next, the mold is tightened. Next, the internal pressure of the bladder is increased. The raw cover is pressed between the cavity surface of the mold and the outer surface of the bladder. The raw cover is heated by heat conduction from the bladder and the mold. The rubber composition of the raw cover flows by pressurization and heating. The rubber composition causes a crosslinking reaction by heating, and the tire 2 is obtained.

  The bladder (not shown) used for manufacturing the tire 2 is provided with a groove. In the tire 2, the rubber composition of the low cover flows into the groove, and the rubber composition causes a crosslinking reaction, whereby the ridges 46 are formed. In the tire 2, it is not necessary to add a new member for suppressing pinch cuts. In the tire 2, an increase in production cost can be suppressed. The tire 2 can be manufactured by an existing production process. In the tire 2, productivity can be maintained.

  As described above, in the tire 2, the ridges 46 are inclined with respect to the circumferential direction. Grooves for forming the ridges 46 provided in the bladder used for manufacturing the tire 2 are also inclined with respect to the circumferential direction. In the tire 2, since this groove can contribute to the discharge of air existing between the low cover and the bladder, the generation of bears can be suppressed. The tire 2 is excellent in appearance quality.

  In the tire 2, the occupancy rate of the ridges 46 in the buttress region 40 is 20% or more. By setting the occupation ratio to 20% or more, the ridges 46 positioned in the buttress area 40 can effectively buffer the impact during compression. In the tire 2, the ridge 46 positioned in the buttress region 40 can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. From the viewpoint that the mass of the tire 2 can be appropriately maintained, the occupation ratio is more preferably 95% or less, and particularly preferably 90% or less.

  In the tire 2, the occupancy ratio of the ridges 46 in the buttress region 40 can be obtained as follows. First, the buttress area 40 is partitioned into 1 cm square small areas. Next, for this small region, the area of the portion where the ridge 46 is present is measured based on the contour of the root 56 of the ridge 46. Next, an average value is calculated based on the obtained measurement value. A numerical value indicating the average value thus obtained as a percentage is the occupation ratio of the ridges 46 in the buttress region 40. In the tire 2, the occupancy ratio of the ridges 46 in the bead area 42 and the boundary area 44 described later can be obtained in the same manner.

  In the tire 2, the occupancy rate of the ridges 46 in the bead region 42 is 20% or more. By setting the occupation ratio to 20% or more, the ridges 46 located in the bead region 42 can effectively buffer the impact during compression. In the tire 2, the ridge 46 positioned in the bead region 42 can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. From the viewpoint that the mass of the tire 2 can be appropriately maintained, the occupation ratio is more preferably 95% or less, and particularly preferably 90% or less.

  In the tire 2, from the viewpoint that excessive mass of the tire 2 can be suppressed, the occupation ratio of the ridges 46 in the boundary region 44 is preferably less than 20%, more preferably 15% or less, and particularly preferably 10% or less. preferable. The occupation ratio is preferably 3% or more from the viewpoint that air discharge during the manufacture of the tire 2 is promoted and appearance quality can be maintained.

  In the tire 2, the difference between the occupation ratio of the ridges 46 in the buttress region 40 and that in the boundary region 44 is 10% from the viewpoint that the impact during compression can be effectively buffered while the increase in mass is suppressed. The above is preferable, and 20% or more is more preferable. Since the upper limit of the occupation ratio of the ridges 46 is 100%, the upper limit value of this difference is 100%.

  In the tire 2, the difference between the occupation ratio of the ridges 46 in the bead region 42 and that in the boundary region 44 is 10% from the viewpoint that the impact during compression can be effectively buffered while the increase in mass is suppressed. The above is preferable, and 20% or more is more preferable. Since the upper limit of the occupation ratio of the ridges 46 is 100%, the upper limit value of this difference is 100%.

  In FIG. 3, the double arrow line H1 represents the height from the inner surface 38a to the tip 58a of the first protrusion 46a. This height H1 is the radial height of the first protrusion 46a. A double arrow line W1 represents the width of the first ridge 46a. The width W1 is obtained by measuring the length from one root 56a of the first ridge 46a to the other root 56a. A double arrow line D1 is a distance between one first ridge 46a and another first ridge 46a located next to the first first ridge 46a. This distance D1 is obtained by measuring the length from the root 56a of one first ridge 46a to the root 56a of the other first ridge 46a.

  In the tire 2, the height H1 is preferably not less than 0.3 mm and not more than 3 mm. By setting the height H1 to be equal to or greater than 0.3 mm, the first ridge 46a can effectively buffer the impact during the compression. In the tire 2, the first protrusion 46a can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. From this viewpoint, the height H1 is more preferably 0.4 mm or more. By setting the height H1 to 3 mm or less, the mass of the tire 2 can be appropriately maintained. In this respect, the height H1 is more preferably equal to or less than 1.0 mm, and particularly preferably equal to or less than 0.6 mm.

  In the tire 2, the width W1 is preferably 1 mm or greater and 4 mm or less. By setting the width W1 to be 1 mm or more, the first ridge 46a can effectively buffer the impact during compression. In the tire 2, the first protrusion 46a can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. From this viewpoint, the width W1 is more preferably 1.5 mm or more. By setting the width W1 to 4 mm or less, the mass of the tire 2 can be appropriately maintained. In this respect, the width W1 is more preferably 2 mm or less.

  In the tire 2, the distance D1 is preferably 4 mm or less. By setting the distance D1 to be 4 mm or more, the occupation ratio of the ridges 46 in the buttress region 40 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be effectively suppressed. The tire 2 is excellent in durability. From this viewpoint, the distance D1 is more preferably 2 mm or more. From the viewpoint that the mass of the tire 2 can be appropriately maintained, the distance D1 is more preferably 1.5 mm or more.

  In the tire 2, the ratio of the distance D1 to the height H1 is preferably 2.5 or more and 4.5 or less. By setting this ratio to 2.5 or more, the mass of the tire 2 can be appropriately maintained. By setting this ratio to 4.5 or less, the occupation ratio of the ridges 46 in the buttress region 40 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be effectively suppressed. The tire 2 is excellent in durability.

  In FIG. 4, the double arrow line H2 represents the height from the inner surface 38a to the tip 58b of the second ridge 46b. This height H2 is the height in the radial direction of the second ridge 46b. A double arrow line W2 represents the width of the second ridge 46b. This width W2 is obtained by measuring the length from one root 56b of the second ridge 46b to the other root 56b. A double arrow line D2 is an interval between one second ridge 46b and another second ridge 46b located next to the one second ridge 46b. This distance D2 is obtained by measuring the length from the root 56b of one second ridge 46b to the root 56b of the other second ridge 46b.

  In the tire 2, the height H2 is preferably not less than 0.3 mm and not more than 3 mm. By setting the height H2 to be 0.3 mm or more, the second ridge 46b can effectively buffer the impact during compression. In the tire 2, the second ridge 46b can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. From this viewpoint, the height H2 is more preferably 0.4 mm or more. By setting the height H2 to 3 mm or less, the mass of the tire 2 can be appropriately maintained. In this respect, the height H2 is more preferably equal to or less than 1.0 mm, and particularly preferably equal to or less than 0.6 mm.

  In the tire 2, the width W2 is preferably 1 mm or greater and 4 mm or less. By setting the width W2 to be 1 mm or more, the second ridge 46b can effectively buffer the impact during the compression. In the tire 2, the second ridge 46b can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. In this respect, the width W2 is more preferably 1.5 mm or more. By setting the width W2 to 4 mm or less, the mass of the tire 2 can be appropriately maintained. In this respect, the width W2 is more preferably 2 mm or less.

  In the tire 2, the distance D2 is preferably 4 mm or less. By setting the distance D2 to be 4 mm or more, the occupation ratio of the ridges 46 in the bead region 42 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be effectively suppressed. The tire 2 is excellent in durability. From this viewpoint, the distance D2 is more preferably 2 mm or more. From the viewpoint that the mass of the tire 2 can be appropriately maintained, the distance D2 is more preferably 1.5 mm or more.

  In the tire 2, the ratio of the distance D2 to the height H2 is preferably 2.5 or more and 4.5 or less. By setting this ratio to 2.5 or more, the mass of the tire 2 can be appropriately maintained. By setting this ratio to 4.5 or less, the occupancy rate of the ridges 46 in the bead region 42 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be effectively suppressed. The tire 2 is excellent in durability.

  In FIG. 5, the double arrow line H3 represents the height from the inner surface 38a to the tip 58c of the third protrusion 46c. This height H3 is the radial height of the third protrusion 46c. A double arrow line W3 represents the width of the third ridge 46c. This width W3 is obtained by measuring the length from one root 56c of the third ridge 46c to the other root 56c. A double arrow line D3 is a distance between one third ridge 46c and another third ridge 46c located next to the one third ridge 46c. This distance D3 is obtained by measuring the length from the root 56c of one third ridge 46c to the root 56c of the other third ridge 46c.

  In the tire 2, the height H3 is preferably not less than 0.3 mm and not more than 3 mm. By setting the height H3 to be 0.3 mm or more, the third protrusion 46c can effectively buffer the impact during the compression. In the tire 2, the third protrusion 46c can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. From this viewpoint, the height H3 is more preferably 0.4 mm or more. By setting the height H3 to 3 mm or less, the mass of the tire 2 can be appropriately maintained. In this respect, the height H3 is more preferably equal to or less than 1.0 mm, and particularly preferably equal to or less than 0.6 mm.

  In the tire 2, the width W3 is preferably 1 mm or more and 4 mm or less. By setting the width W3 to be 1 mm or more, the third protrusion 46c can effectively buffer the impact during compression. In the tire 2, the third protrusion 46c can contribute to the suppression of pinch cuts. The tire 2 is excellent in durability. In this respect, the width W3 is more preferably 1.5 mm or more. By setting the width W3 to 4 mm or less, the mass of the tire 2 can be appropriately maintained. In this respect, the width W3 is more preferably 2 mm or less.

  In the tire 2, the distance D3 is preferably 4 mm or less. By setting the distance D3 to be 4 mm or more, the occupation ratio of the ridges 46 in the buttress area 40 and the bead area 42 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be effectively suppressed. The tire 2 is excellent in durability. From this viewpoint, the distance D3 is more preferably 2 mm or more. From the viewpoint that the mass of the tire 2 can be appropriately maintained, the distance D3 is more preferably 1.5 mm or more.

  In the tire 2, the ratio of the distance D3 to the height H3 is preferably 2.5 or more and 4.5 or less. By setting this ratio to 2.5 or more, the mass of the tire 2 can be appropriately maintained. By setting this ratio to 4.5 or less, the occupation ratio of the ridges 46 in the buttress area 40 and the bead area 42 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be effectively suppressed. The tire 2 is excellent in durability.

  In FIG. 2, the double arrow line HC represents the height in the radial direction from the solid line LA indicating the boundary between the tread portion T and the side portion S to the other end 50b of the first protrusion 46a. The double arrow line HD represents the height in the radial direction from the bead base line to one end 52a of the second ridge 46b. In FIG. 2, the double arrow line HA is the height in the radial direction of the inner surface 38 a of the side portion S. In the tire 2, the portion indicated by the height HC and the portion indicated by the height HD are referred to as a buffer portion.

  In the tire 2, the ratio of the height HC to the height HA is preferably 10% or more and 30% or less. By setting this ratio to 10% or more, the occupation ratio of the ridges 46 in the buttress region 40 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be suppressed. The tire 2 is excellent in durability. From this viewpoint, the ratio is more preferably 15% or more. By setting this ratio to 30% or less, the mass of the tire 2 can be appropriately maintained. In this respect, the ratio is more preferably equal to or less than 25%.

  In the tire 2, the ratio of the height HD to the height HA is preferably 30% or more and 70% or less. By setting this ratio to 10% or more, the occupation ratio of the ridges 46 in the bead region 42 can be appropriately maintained. In the tire 2, the impact at the time of compression can be effectively buffered. In the tire 2, pinch cuts can be suppressed. The tire 2 is excellent in durability. In this respect, the ratio is more preferably equal to or greater than 50%. By setting this ratio to 70% or less, the mass of the tire 2 can be appropriately maintained. In this respect, the ratio is more preferably equal to or less than 60%.

  In the present invention, the dimensions and angles of the tire 2 and each member of the tire to be described later are measured in a state in which 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.

  FIG. 6 is a development view showing a part of a pneumatic tire 60 according to another embodiment of the present invention. In FIG. 6, the vertical direction is the radial direction, the horizontal direction is the circumferential direction, and the direction perpendicular to the paper surface is the axial direction. FIG. 6 shows an inner surface 62 of the side portion S that constitutes the tire 60. A large number of ridges 64 are provided on the inner surface 62. The tire 60 is the same as the tire 2 of FIG. 1 except for the configuration of the ridges 64. The tire 60 also includes a tread portion T and a pair of side portions S.

  In FIG. 6, the solid line LA represents the boundary between the tread portion T and the side portion S. This boundary is also the outer end of the inner surface 62 of the side portion S. A solid line BBL is a bead base line. A double arrow line HA represents the height in the radial direction from the bead base line to the solid line LA. This height HA is the radial height of the inner surface 62 of the side portion S. The solid line LB is located away from the solid line LA in the radial direction by a distance corresponding to 20% of the height HA. The solid line LC is located at a distance from the bead base line in the radial direction corresponding to 55% of the height HA. The solid line LD is at a position away from the bead base line by a distance corresponding to 10% of the height HA in the radial direction. In the tire 60, a portion from the solid line LA to the solid line LB is a buttress region 66 on the inner surface 38, and a portion from the solid line LC to the solid line LD is a bead region 68. A portion located between the buttress area 66 and the bead area 68 is a boundary area 70. In the tire 60, the inner surface 62 of the side portion S has a buttress area 66 located on the radially outer side and a bead area 68 located on the radially inner side.

  As shown in the drawing, in the tire 60, the ridge 64 provided on the inner surface 62 includes a first ridge 64a extending from the inner end 72 toward the left in the radial direction, and an inner end thereof. A second ridge 64b extending rightwardly outward from 72, a third ridge 64c located on the tread portion T side of the inner surface 62, and an inner end of the inner surface 62 It is comprised from the 4th protruding item | line 64d located in the 48 side.

  The first ridge 64a is inclined with respect to the circumferential direction. The first ridge 64 a is disposed on the entire inner surface 62 of the side portion S. Although not shown, the first protrusion 64a protrudes from the inner surface 62. The outline of the cross section of the first ridge 64a is an arc.

  The second ridge 64b is inclined with respect to the circumferential direction. The second ridge 64b is disposed on the entire inner surface 62 of the side portion S. Although not shown, the second ridge 64 b protrudes from the inner surface 62. The outline of the cross section of the second ridge 64b is an arc. The second ridge 64b and the first ridge 64a intersect each other. These ridges 64 are arranged in a lattice pattern.

  The third ridge 64 c is disposed in part of the buttress area 66 and the boundary area 70. The third ridge 64c extends from one second ridge 64b toward another second ridge 64b parallel to the one second ridge 64b. The third ridge 64c is along the first ridge 64a. The third ridge 64c is inclined with respect to the circumferential direction. Although not shown, the third protrusion 64c protrudes from the inner surface 62. The outline of the cross section of the third ridge 64c is an arc.

  The fourth ridge 64d is disposed in the bead region 68. The fourth ridge 64d extends from one second ridge 64b toward another second ridge 64b parallel to the one second ridge 64b. The fourth ridge 64d is along the first ridge 64a. The fourth ridge 64d is inclined with respect to the circumferential direction. Although not shown, the fourth protrusion 64 d protrudes from the inner surface 62. The outline of the cross section of the fourth ridge 64d is an arc.

  As described above, in the tire 60, the ridge 64 protrudes from the inner surface 62. The ridge 64 can buffer the impact during compression. In the tire 60, the pinch cut can be suppressed. The tire 60 is excellent in durability.

  In the tire 60, the buttress area 66 is appropriately occupied by a large number of ridges 64. The buttress area 66 is an area where the ridges 64 exist at a high density (a high density area). In the tire 60, the impact during compression can be effectively buffered. In the tire 60, the pinch cut can be suppressed. The tire 60 is excellent in durability.

  In the tire 60, the occupancy rate of the ridges 64 in the buttress region 66 is larger than the occupancy rate of the ridges 64 in the boundary region 70. In the tire 60, an impact during compression can be effectively buffered while an increase in mass is suppressed. In the tire 60, the pinch cut can be suppressed. The tire 60 is excellent in durability. In the tire 60, the rigidity can be appropriately maintained, so that the riding comfort is not hindered.

  In the tire 60, the occupancy rate of the ridges 64 in the buttress region 66 is 20% or more. By setting the occupation ratio to 20% or more, the ridges 64 positioned in the buttress area 66 can effectively buffer the impact during compression. In the tire 60, the ridges 64 positioned in the buttress region 66 can contribute to the suppression of pinch cuts. The tire 60 is excellent in durability. From the viewpoint that the mass of the tire 60 can be appropriately maintained, the occupation ratio is more preferably 95% or less, and particularly preferably 90% or less.

  In the tire 60, the bead region 68 is appropriately occupied by a large number of ridges 64. The bead area 68 is an area where the ridges 64 exist at a high density (a high density area). In the tire 60, the impact during compression can be effectively buffered. In the tire 60, the pinch cut can be suppressed. The tire 60 is excellent in durability.

  In the tire 60, the occupancy rate of the ridges 64 in the bead region 68 is larger than the occupancy rate of the ridges 64 in the boundary region 70. In the tire 60, the impact during compression can be effectively buffered while the increase in mass is suppressed. In the tire 60, the pinch cut can be suppressed. The tire 60 is excellent in durability. In the tire 60, the rigidity can be appropriately maintained, so that the riding comfort is not hindered.

  In the tire 60, the occupancy rate of the ridges 64 in the bead region 68 is 20% or more. By setting this occupation ratio to 20% or more, the ridges 64 positioned in the bead region 68 can effectively buffer the impact during compression. In the tire 60, the ridges 64 positioned in the bead region 68 can contribute to suppression of pinch cuts. The tire 60 is excellent in durability. From the viewpoint that the mass of the tire 60 can be appropriately maintained, the occupation ratio is more preferably 95% or less, and particularly preferably 90% or less.

  The bladder (not shown) used for manufacturing the tire 60 is also provided with a groove in the same manner as the bladder used for manufacturing the tire 60 of FIG. In the tire 60, the rubber composition flows into the groove, and the rubber composition causes a crosslinking reaction, whereby the ridges 64 are formed. In the tire 60, it is not necessary to add a new member for suppressing pinch cuts. In the tire 60, an increase in production cost can be suppressed. The tire 60 can be manufactured by an existing production process. In the tire 60, productivity can be maintained.

  As described above, in the tire 60, the ridges 64 are inclined with respect to the circumferential direction. The grooves for forming the ridges 64 provided in the bladder used for manufacturing the tire 60 are also inclined with respect to the circumferential direction. In the tire 60, since this groove can contribute to the discharge of air existing between the low cover and the bladder, the generation of bears can be suppressed. The tire 60 is excellent in appearance quality.

  In the tire 60, the portion from the solid line LA indicating the boundary between the tread portion T and the side portion S to the end 74 (inner end) located on the radially inner side of the third protrusion 64c is referred to as a first buffer portion. Is done. In FIG. 6, a double arrow line HE represents the radial height of the first buffer portion. In the tire 60, the portion from the bead base line to the end 76 (outer end) located on the radially outer side of the fourth protrusion 64d is referred to as a second buffer portion. In FIG. 6, a double arrow line HF represents the height in the radial direction of the second buffer portion.

  In the tire 60, the ratio of the height HE to the height HA is preferably 10% or more and 30% or less. By setting this ratio to 10% or more, the occupation ratio of the ridges 64 in the buttress region 66 can be appropriately maintained. In the tire 60, the impact during compression can be effectively buffered. In the tire 60, the pinch cut can be suppressed. The tire 60 is excellent in durability. From this viewpoint, the ratio is more preferably 15% or more. By setting this ratio to 30% or less, the mass of the tire 60 can be appropriately maintained. In this respect, the ratio is more preferably equal to or less than 25%.

  In the tire 60, the ratio of the height HF to the height HA is preferably 30% or more and 70% or less. By setting this ratio to 10% or more, the occupancy rate of the ridges 64 in the bead region 68 can be appropriately maintained. In the tire 60, the impact during compression can be effectively buffered. In the tire 60, the pinch cut can be suppressed. The tire 60 is excellent in durability. In this respect, the ratio is more preferably equal to or greater than 50%. By setting this ratio to 70% or less, the mass of the tire 60 can be appropriately maintained. In this respect, the ratio is more preferably equal to or less than 60%.

  FIG. 7 is a developed view showing a part of a pneumatic tire 78 according to another embodiment of the present invention. In FIG. 7, the vertical direction is the radial direction, the horizontal direction is the circumferential direction, and the direction perpendicular to the paper surface is the axial direction. FIG. 7 shows the inner surface 80 of the side portion S that constitutes the tire 78. A large number of ridges 82 are provided on the inner surface 80. The tire 78 is the same as the tire 2 in FIG. 1 except for the configuration of the ridges 82. The tire 78 also includes a tread portion T and a pair of side portions S.

  In FIG. 7, the solid line LA represents the boundary between the tread portion T and the side portion S. This boundary is also the outer end of the inner surface 80 of the side portion S. A solid line BBL is a bead base line. A double arrow line HA represents the height in the radial direction from the bead base line to the solid line LA. This height HA is the radial height of the inner surface 80 of the side portion S. The solid line LB is located away from the solid line LA in the radial direction by a distance corresponding to 20% of the height HA. The solid line LC is located at a distance from the bead base line in the radial direction corresponding to 55% of the height HA. The solid line LD is at a position away from the bead base line by a distance corresponding to 10% of the height HA in the radial direction. In the tire 78, a portion from the solid line LA to the solid line LB on the inner surface 80 is a buttress region 84, and a portion from the solid line LC to the solid line LD is a bead region 86. A portion located between the buttress area 84 and the bead area 86 is a boundary area 88. In the tire 78, the inner surface 80 of the side portion S has a buttress area 84 located on the radially outer side and a bead area 86 located on the radially inner side.

  As shown in the figure, in this tire 78, the ridges 82 provided on the inner surface 80 are located on the first ridge 82a located on the tread portion T side and on the inner end 90 side. And the second ridge 82b.

  One end 92a of the first ridge 82a is located on the straight line LA. The first ridge 82a extends downward from the one end 92a inward in the radial direction. The first ridge 82a is inclined with respect to the circumferential direction. The other end 92 b of the first ridge 82 a is located in the boundary region 88. In the tire 78, the first ridge 82 a is disposed in part of the buttress area 84 and the boundary area 88. Although not shown, the first ridge 82 a protrudes from the inner surface 80. The outline of the cross section of the first ridge 82a is an arc.

  One end 94a of the second ridge 82b is located on the radially inner side of the other end 94b of the first ridge 82a. The second ridge 82b is separated from the first ridge 82a in the radial direction. The second protrusion 82b extends downward from the one end 94a inward in the radial direction. The second ridge 82b is inclined with respect to the circumferential direction. One end 94 a and the other end 94 b of the second ridge 82 b are located in the bead region 86. In the tire 78, the second ridge 82 b is located in the bead region 86. Although not shown, the second protrusion 82b protrudes from the inner surface 80. The outline of the cross section of the second ridge 82b is an arc.

  As described above, in the tire 78, the ridge 82 projects from the inner surface 80. The ridge 82 can buffer the impact during compression. In the tire 78, pinch cuts can be suppressed. The tire 78 is excellent in durability.

  In the tire 78, the buttress area 84 is appropriately occupied by a large number of ridges 82. The buttress area 84 is an area where the ridges 82 exist at a high density (a high density area). In the tire 78, the impact during compression can be effectively buffered. In the tire 78, pinch cuts can be suppressed. The tire 78 is excellent in durability.

  In the tire 78, the occupancy rate of the ridges 82 in the buttress region 84 is larger than the occupancy rate of the ridges 82 in the boundary region 88. In the tire 78, the impact during compression can be effectively buffered while suppressing an increase in mass. In the tire 78, pinch cuts can be suppressed. The tire 78 is excellent in durability. In the tire 78, the rigidity can be appropriately maintained, so that the riding comfort is not hindered.

  In the tire 78, the occupation ratio of the ridges 82 in the buttress region 84 is 20% or more. By setting the occupation ratio to 20% or more, the ridges 82 positioned in the buttress area 84 can effectively buffer the impact during compression. In the tire 78, the ridge 82 located in the buttress area 84 can contribute to the suppression of pinch cuts. The tire 78 is excellent in durability. From the viewpoint that the mass of the tire 78 can be appropriately maintained, the occupation ratio is more preferably 95% or less, and particularly preferably 90% or less.

  In the tire 78, the bead region 86 is appropriately occupied by a large number of ridges 82. The bead area 86 is an area where the ridges 82 exist at a high density (a high density area). In the tire 78, the impact during compression can be effectively buffered. In the tire 78, pinch cuts can be suppressed. The tire 78 is excellent in durability.

  In the tire 78, the occupancy rate of the ridges 82 in the bead region 86 is larger than the occupancy rate of the ridges 82 in the boundary region 88. In the tire 78, the impact during compression can be effectively buffered while the increase in mass is suppressed. In the tire 78, pinch cuts can be suppressed. The tire 78 is excellent in durability. In the tire 78, the rigidity can be appropriately maintained, so that the riding comfort is not hindered.

  In the tire 78, the occupation ratio of the ridges 82 in the bead region 86 is 20% or more. By setting this occupation ratio to 20% or more, the ridge 82 located in the bead region 86 can effectively buffer the impact during compression. In the tire 78, the ridge 82 located in the bead region 86 can contribute to suppression of pinch cuts. The tire 78 is excellent in durability. From the viewpoint that the mass of the tire 78 can be appropriately maintained, the occupation ratio is more preferably 95% or less, and particularly preferably 90% or less.

  The bladder (not shown) used for manufacturing the tire 78 is also provided with a groove in the same manner as the bladder used for manufacturing the tire 78 of FIG. In the tire 78, the rubber composition flows into the groove, and the rubber composition causes a crosslinking reaction, whereby the ridge 82 is formed. In the tire 78, it is not necessary to add a new member for suppressing pinch cuts. In the tire 78, an increase in production cost can be suppressed. The tire 78 can be manufactured by an existing production process. In the tire 78, productivity can be maintained.

  As described above, in the tire 78, the ridges 82 are inclined with respect to the circumferential direction. The grooves for forming the ridges 82 provided in the bladder used for manufacturing the tire 78 are also inclined with respect to the circumferential direction. In the tire 78, since this groove can contribute to the discharge of air existing between the low cover and the bladder, the generation of bears can be suppressed. The tire 78 is excellent in appearance quality.

  In FIG. 7, the double arrow line HG represents the height in the radial direction from the solid line LA indicating the boundary between the tread portion T and the side portion S to the other end 92b of the first protrusion 82a. The double arrow line HH represents the height in the radial direction from the bead base line to one end 94a of the second ridge 82b. In the tire 78, the portion indicated by the height HG and the portion indicated by the height HH are referred to as a buffer portion.

  In the tire 78, the ratio of the height HG to the height HA is preferably 10% or more and 30% or less. By setting this ratio to 10% or more, the occupation ratio of the ridges 82 in the buttress region 84 can be appropriately maintained. In the tire 78, the impact during compression can be effectively buffered. In the tire 78, the pinch cut can be suppressed. The tire 78 is excellent in durability. From this viewpoint, the ratio is more preferably 15% or more. By setting this ratio to 30% or less, the mass of the tire 78 can be appropriately maintained. In this respect, the ratio is more preferably equal to or less than 25%.

  In the tire 78, the ratio of the height HH to the height HA is preferably 30% or more and 70% or less. By setting this ratio to 10% or more, the occupation ratio of the ridges 82 in the bead region 86 can be appropriately maintained. In the tire 78, the impact during compression can be effectively buffered. In the tire 78, pinch cuts can be suppressed. The tire 78 is excellent in durability. In this respect, the ratio is more preferably equal to or greater than 50%. By setting this ratio to 70% or less, the mass of the tire 78 can be appropriately maintained. In this respect, the ratio is more preferably equal to or less than 60%.

  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 of Example 1 having the basic configuration shown in FIG. 1 and having the specifications shown in Table 1 below was obtained. The tire size is 225 / 45R18. A large number of ridges having the configuration shown in FIG. 2 are provided on the inner surface of the tire. The cross-sectional shape of these ridges is a semicircle. The height in the radial direction of these ridges is 2 mm. In this tire, the ridge occupation ratio in the buttress area is 60%, the ridge occupation ratio in the bead area is 60%, and the ridge occupation ratio in the boundary area is 7%.

[Examples 2 to 3 and Comparative Example 3]
A tire was obtained in the same manner as in Example 1 except that the occupancy ratio of the ridges was as shown in Table 1 below.

[Example 10]
A tire was obtained in the same manner as in Example 1 except that the height of the ridges in the radial direction was 4 mm.

[Examples 4 to 8 and Comparative Example 4]
A tire was obtained in the same manner as in Example 1 except that a large number of ridges having the configuration shown in FIG. 7 were provided on the inner surface of the main body and the occupancy of the ridges was changed.

[Example 9]
A tire was obtained in the same manner as in Example 1 except that a large number of ridges having the configuration shown in FIG. 6 were provided on the inner surface of the main body and the occupancy of the ridges was changed.

[Comparative Example 1]
Comparative Example 1 is a conventional tire that is commercially available. In the comparative example 1, a large number of ridges extending outward in the radial direction from the inner end of the inner surface of the side portion S are provided. The occupancy ratio of the ridges in the buttress area, the occupancy ratio of the ridges in the boundary area, and the occupancy ratio of the ridges in the bead area are all 10%.

[Comparative Example 2]
Comparative Example 2 is a conventional tire that is commercially available. In this comparative example 2, a large number of ridges extending radially outward from the inner end of the inner surface of the side portion S are provided. The occupancy ratio of the ridges in the buttress area, the occupancy ratio of the ridges in the boundary area, and the occupancy ratio of the ridges in the bead area are all 15%.

[Appearance evaluation]
The appearance of the prototype tire was visually observed. The results are shown in Table 1 and Table 2 below as “G” when the appearance quality is excellent and “B” when the appearance quality is inferior.

[Productivity evaluation]
Productivity was evaluated by calculating the cost required to produce a single prototype tire. The results are shown in Tables 1 and 2 below as “G” when the production cost is equal to or lower than that of Comparative Example 1 and “B” when the production cost is higher than that of Comparative Example 1. Has been.

[Riding comfort evaluation]
The prototype tire was mounted on a passenger car (FR car) having a displacement of 2500 cc. The internal pressure of this tire was 240 kPa. The size of the wheel is 18 × 8J. This passenger car was subjected to a running test on an asphalt road surface and a driver's sensory evaluation was performed on the ride comfort. This result is expressed as an index value with Comparative Example 1 as 100. Larger values indicate better results. The results are shown in Tables 1 and 2 below.

[Cut resistance evaluation]
The prototype tire was mounted on the rim and secured to the horizontal fixed shaft of the cut resistance evaluation device. The rim size was 18 × 8 J, and the tire internal pressure was 230 kPa. A block-shaped weight (mass 300 kg) was freely dropped and collided with the tread surface (the portion from the tire equator surface to the end of one tread) of the prototype tire. The sidewall was locally bent by the collision of the weight. The appearance of the side wall after the collision was visually observed to check for the occurrence of pinch cuts (side wall swelling). If there was no pinch cut, the weight was allowed to fall freely from a higher position and hit the tire. The product (fracture energy) of the height of the weight and the mass when the occurrence of this pinch cut was confirmed was calculated, and cut resistance was evaluated based on this calculated value. This result is expressed as an index value with Comparative Example 1 as 100. It shows that it is excellent in cut resistance, so that this value is large. The results are shown in Tables 1 and 2 below.

  As shown in Tables 1 and 2, the tires of the examples are excellent in productivity, ride comfort and cut resistance. From this evaluation result, the superiority of the present invention is clear.

  The tire according to the present invention can be mounted on various vehicles. .

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 part of the inner surface of the tire of FIG. 1. FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. FIG. 4 is an enlarged cross-sectional view taken along line IV-IV in FIG. FIG. 5 is an enlarged cross-sectional view taken along line VV in FIG. FIG. 6 is a development view showing a part of a pneumatic tire according to another embodiment of the present invention. FIG. 7 is a development view showing a part of a pneumatic tire according to still another embodiment of the present invention.

Explanation of symbols

2, 60, 78 ... tire 4 ... tread 6 ... sidewall 8 ... bead 10 ... carcass 12 ... belt 14 ... band 16 ... inner liner 18 ... Chafer 20 ... Tread surface 22 ... Groove 24 ... Core 26 ... Apex 28 ... Ply 32 ... Inner layer 34 ... Outer layer 38, 38a, 62, 80 ... Inner surface 40, 66, 84 ... buttress area 42, 68, 86 ... bead area 44, 70, 88 ... boundary area 46, 46a, 46b, 46c, 64, 64a, 64b, 64c, 82, 82a, 82b, 82c ... ridge

Claims (3)

It consists of a tread part and a pair of side parts,
Each side part has a large number of ridges on its inner surface,
This inner surface has a buttress area located radially outward and a bead area located radially inside,
This buttress area or bead area is a high density area,
A pneumatic tire in which the occupancy ratio of the ridges in the high density region is 20% or more.   In the high-density region, a ratio of a distance between the ridge and another ridge located next to the ridge to a height of the ridge is 2.5 or more and 4.5 or less. Item 14. The tire according to Item 1. The height of the ridges located in the high density region is 0.3 mm or more and 3 mm or less,
The tire according to claim 1 or 2, wherein a width of the ridge is 1 mm or more and 4 mm or less.

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