JP2013147065A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire with excellent durability.SOLUTION: A tire 2 includes a pair of sidewalls 6, a pair of clinches 8, a pair of beads 10, a pair of fillers 64, a pair of inner sidewalls 28, and a carcass 12. The bead 10 has a core 44 and an apex 46. The carcass 12 has a ply 48. Surroundings of the core 44 of the ply 48 are folded from the axial direction inside toward the outside. With the folding made, a main part 50 and a folded part 52 are formed in the ply 48. A filler 64 is located outside the folded part 52 in the axial direction. The radial direction height from a bead base line to an inner end 76 of the inner sidewall 28 is 23 mm or less. A ratio of a thickness T of the clinch 8 to a reference width W of the bead 10 portion is 34% or more, and 50% or less.

Description

  The present invention relates to a pneumatic tire.

  The tire supports the vehicle. A load is applied to the tire. The tire mounted on the small truck is subjected to a load larger than the load applied to the tire mounted on the passenger car.

  The tire is fitted on the rim. At this time, the bead portion of the tire contacts the rim. As described above, a large load is applied to the tire for a light truck. Large loads can cause looseness in the bead portion of the tire. From the viewpoint of improving durability, various studies have been made on reinforcing the bead portion. An example of this study is disclosed in Japanese Patent Laid-Open No. 06-191240.

Japanese Patent Laid-Open No. 06-191240

  From the viewpoint of improving durability, a filler may be provided between the folded portion of the carcass ply and the clinch. In this case, distortion may occur between the clinch and the filler. This distortion hinders durability.

  An inner sidewall may be provided between the clinch and the filler. This inner side wall can relieve the distortion generated between the clinch and the filler. However, the end of the inner side wall may become a starting point of looseness, and there is a problem that sufficient durability cannot be obtained even though the inner side wall is provided.

  An object of the present invention is to provide a pneumatic tire having excellent durability.

  The pneumatic tire according to the present invention has a tread whose outer surface forms a tread surface, a pair of sidewalls that extend substantially inward in the radial direction from the end of the tread, and each that is substantially radially inward from the end of the sidewall. A pair of clinches extending inward, a pair of beads each positioned axially inward of the clinches, a pair of fillers positioned between the beads and the clinches, and A pair of inner sidewalls positioned between the clinch and a carcass spanned between one bead and the other bead along the inside of the tread and the sidewall. The bead includes a core and an apex extending radially outward from the core. The carcass includes a ply. The ply is folded around the core from the inner side toward the outer side in the axial direction. By this folding, a main portion and a folding portion are formed on the ply. The filler is located outside the folded portion in the axial direction. The height in the radial direction from the bead base line to the inner end of the inner sidewall is 23 mm or less. The ratio of the clinch thickness to the reference width of the bead portion is 34% or more and 50% or less.

  Preferably, the pneumatic tire further includes a chafer folded around the bead from the inner side toward the outer side in the axial direction. The chafer is composed of a cloth and a rubber impregnated in the cloth. When the tire is incorporated into the rim, the chafer contacts the rim.

  In the pneumatic tire according to the present invention, the inner end of the inner sidewall is in an appropriate position. In this tire, the inner end of the inner sidewall is less likely to be a starting point of looseness. Moreover, the clinch has an appropriate thickness. This clinch can contribute to suppression of distortion. In this tire, the occurrence of looseness in the bead portion is effectively prevented. This tire is excellent in durability.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a part of the tire of FIG.

  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 sidewall 6, a clinch 8, a bead 10, a carcass 12, a belt 14, a band 16, an edge band 18, an edge strip 20, a first installation 22, a second installation 24, and a filler portion 26. The inner side wall 28, the chafer 30 and the inner liner 32 are provided. The tire 2 is a tubeless type. The tire 2 is attached to a truck, a bus or the like.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 34 that contacts the road surface. A groove 36 is carved in the tread surface 34. The groove 36 forms a tread pattern. The tread 4 has a base layer 38 and a cap layer 40. The cap layer 40 is located on the radially outer side of the base layer 38. The cap layer 40 is laminated on the base layer 38. The base layer 38 is made of a crosslinked rubber in which heat generation due to deformation is suppressed. The cap layer 40 is made of a crosslinked rubber having excellent wear resistance, heat resistance, and grip properties.

  The sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. A radially outer end of the sidewall 6 is joined to the tread 4. The radially inner end of the sidewall 6 is joined to the clinch 8. 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.

  The 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. The clinch 8 is in contact with the flange of the rim on which the tire 2 is mounted. The protrusion provided at the boundary between the clinches 8 and the sidewalls 6 is a clincher line 42. When the tire 2 is mounted on a rim on which the tire 2 is mounted, the inner portion of the clincher line 42 is accommodated in the flange of the rim in the radial direction.

  The bead 10 is located inside the clinch 8 in the axial direction. The bead 10 includes a core 44 and an apex 46 that extends radially outward from the core 44. The core 44 is ring-shaped and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 46 is tapered outward in the radial direction. The apex 46 is made of a highly hard crosslinked rubber.

  The carcass 12 includes a first ply 48a, a second ply 48b, and a third ply 48c. The first ply 48 a, the second ply 48 b, and the third ply 48 c are bridged between the beads 10 on both sides and are along the tread 4 and the sidewall 6. The first ply 48a is folded around the core 44 from the inner side to the outer side in the axial direction. By this folding, a main portion 50a and a folding portion 52a are formed in the first ply 48a. The second ply 48b is folded around the core 44 from the inner side to the outer side in the axial direction. By this folding, the main portion 50b and the folding portion 52b are formed in the second ply 48b. The end 54a of the folded portion 52a of the first ply 48a is located outside the end 54b of the folded portion 52b of the second ply 48b in the radial direction. The third ply 48c is located outside the first ply 48a and the second ply 48b. The third ply 48 c extends from the equator plane toward the bead 10. An end 54c of the third ply 48c is located outside the bead 10 in the axial direction. The third ply 48 c is not folded back around the core 44. In the tire 2, the folded portion 52a of the first ply 48a is located on the axially outer side of the folded portion 52b of the second ply 48b. A portion of the end 54c of the third ply 48c is located outside the folded portion 52a of the first ply 48a in the axial direction.

  Each ply 48 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, and aramid fibers. Particularly preferred organic fibers are polyester fibers. From the viewpoint of the rigidity of the tire 2, the carcass 12 is preferably formed from two or more plies 48.

  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 56a and an outer layer 56b. As is apparent from FIG. 1, the width of the inner layer 56a is slightly larger than the width of the outer layer 56b in the axial direction. Although not shown, each of the inner layer 56a and the outer layer 56b 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 usually 10 ° to 35 °. The inclination direction of the cord of the inner layer 56a with respect to the equator plane is opposite to the inclination direction of the cord of the outer layer 56b 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 56.

  In the tire 2, the end of the inner layer 56a is covered with a first cover 58a. The end of the outer layer 56b is covered with a second cover 58b. In other words, the belt 14 of the tire 2 includes a first cover 58a and a second cover 58b in addition to the inner layer 56a and the outer layer 56b. The first cover 58a and the second cover 58b are made of a crosslinked rubber. Each cover 58 constrains the end of each layer 56.

  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 substantially equal to 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, and aramid fibers.

  The edge band 18 is located radially outside the belt 14 and in the vicinity of the end of the belt 14. The edge band 18 of the tire 2 is located inside the band 16 in the radial direction. Although not shown, the edge band 18 is made 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 end of the belt 14 is restrained by this cord, the 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 edge strip 20 is located radially outside the band 16 and in the vicinity of the end of the band 16. The edge strip 20 of the tire 2 is located between the tread 4 and the band 16. The edge strip 20 is made of a crosslinked rubber. The edge strip 20 restrains the end portion of the band 16, in other words, the end portion of the belt 14. The edge strip 20 can contribute to high speed durability.

  The first insulation 22 is made of a crosslinked rubber. The first insulation 22 is laminated on the second ply 48 b that constitutes the carcass 12. The first insulation 22 is spanned between the beads 10 on both sides, and extends along the tread 4 and the sidewall 6. The first insulation 22 is folded around the core 44 from the inner side toward the outer side in the axial direction. By this folding, the main portion 60a and the folding portion 60b are formed in the first installation 22. In the portion of the equator surface of the tire 2, a third ply 48 c constituting the carcass 12 is laminated on the first insulation 22.

  The second insulation 24 is made of a crosslinked rubber. The second insulation 24 is located outside the carcass 12 in the axial direction. The portion of the inner end 62 of the second insulation 24 overlaps with the apex 46 of the bead 10 in the axial direction. The second insulation 24 extends in the radial direction along the third ply 48c. In the tire 2, the inner end 62 portion of the second insulation 24 is located between the carcass 12 and the filler portion 26. The second insulation 24 can relieve distortion generated between the carcass 12 and the filler portion 26.

  The filler part 26 is located outside the bead 10 in the axial direction. The filler portion 26 is located inside the clinch 8 in the axial direction. In other words, the filler part 26 is located between the bead 10 and the clinch 8.

  In the tire 2, the filler portion 26 is composed of a first filler 64a and a second filler 64b. The first filler 64a forms an axially inner portion of the filler portion 26. The second filler 64 b forms an outer portion in the axial direction of the filler portion 26.

  The first filler 64a is located outside the carcass 12 in the axial direction. More specifically, the first filler 64a is located outside the third ply 48c in the axial direction. A folded portion 52a of the first ply 48a is positioned on the inner side in the axial direction of the third ply 48c. Accordingly, the first filler 64a is located outside the folded portion 52a of the first ply 48a in the axial direction.

  In the tire 2, the first filler 64 a extends in the radial direction along the carcass 12. The outer end 66a of the first filler 64a is located inside the outer end 66b of the second filler 64b in the radial direction. The inner end 68a of the first filler 64a is located outside the inner end 68b of the second filler 64b in the radial direction. The first filler 64a is covered with a second filler 64b. The inner end 68a of the first filler 64a is located inside the upper surface 70 of the core 44 of the bead 10 in the radial direction. The portion of the inner end 68a of the first filler 64a overlaps with the core 44 in the axial direction.

  The second filler 64b is located outside the first filler 64a in the axial direction. As described above, the first filler 64a is located outside the folded portion 52a of the first ply 48a in the axial direction. Accordingly, the second filler 64b is also located outside the folded portion 52a of the first ply 48a in the axial direction.

  In the tire 2, the second filler 64 b extends in the radial direction along the carcass 12. The outer end 66b of the second filler 64b is located inside the tip 72 of the apex 46 of the bead 10 in the radial direction. The outer end 66b of the second filler 64b is located outside the outer end 74 of the clinch 8 in the radial direction. In the tire 2, the inner end 68b of the second filler 64b is located inside the end 54c of the third ply 48c in the radial direction. The inner end 68b of the second filler 64b is located inside the upper surface 70 of the core 44 of the bead 10 in the radial direction. The portion of the inner end 68b of the second filler 64b overlaps with the core 44 in the axial direction. In the tire 2, the inner end 68b of the second filler 64b is located inside the inner end 68a of the first filler 64a in the radial direction. In the tire 2, the inner end 68 b of the second filler 64 b is the inner end of the filler portion 26.

  Although not shown, each of the first filler 64a and the second filler 64b includes a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the radial direction. The inclination direction with respect to the radial direction of the cord of the first filler 64a is opposite to the inclination direction with respect to the radial direction of the cord of the second filler 64b. The cord is made of organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, and aramid fibers. Particularly preferred organic fibers are nylon fibers. In the tire 2, the filler portion 26 can contribute to the rigidity of the bead 10 portion of the tire 2.

  The inner sidewall 28 is located between the filler portion 26 and the clinch 8. More specifically, the inner sidewall 28 is located between the second filler 64 b and the clinch 8.

  In the tire 2, the inner side wall 28 extends in the radial direction along the second filler 64b. The inner end 76 of the inner sidewall 28 is located in the vicinity of the core 44 of the bead 10. The outer end 78 of the inner side wall 28 is located inside the outer end 74 of the clinch 8 in the radial direction. In the tire 2, the inner sidewall 28 is made of a crosslinked rubber. As is clear from FIG. 1, the inner sidewall 28 is sandwiched between the second filler 64 b and the clinch 8. The inner side wall 28 can alleviate distortion generated between the clinch 8 and the filler portion 26.

  The chafer 30 is located in the vicinity of the bead 10. The chafer 30 is folded around the core 44 of the bead 10 from the inner side to the outer side in the axial direction. When the tire 2 is incorporated in the rim, the chafer 30 comes into contact with the rim. In the tire 2, the chafer 30 is made of a cloth and rubber impregnated in the cloth. The chafer 30 is also called a canvas chafer. The chafer 30 can appropriately maintain the shape of the bead 10 when the tire 2 is manufactured. The chafer 30 can effectively prevent a defect such as a long toe from occurring in the bead 10 portion of the tire 2.

  The inner liner 32 is located inside the carcass 12. The inner liner 32 is joined to the inner surface of the carcass 12. The inner liner 32 is made of a crosslinked rubber. For the inner liner 32, rubber having excellent air shielding properties is used. A typical base rubber of the inner liner 32 is butyl rubber or halogenated butyl rubber. The inner liner 32 holds the internal pressure of the tire 2.

  In the tire 2, the inner end 76 of the inner sidewall 28 is located inside the clincher line 42 in the radial direction. In the tire 2, the inner end 76 of the inner sidewall 28 is disposed at a position that fits in the flange of the rim when the tire 2 is mounted on the rim. In the tire 2, it is possible to prevent looseness starting from the inner end 76 of the inner sidewall 28. The tire 2 is excellent in durability.

  In the tire 2, the clinch 8 has an appropriate thickness. The clinch 8 can contribute to alleviation of distortion generated at the inner end 76 of the inner sidewall 28. The clinch 8 can contribute to improvement of durability.

  FIG. 2 shows a portion of the bead 10 of the tire 2 of FIG. In FIG. 1, a solid line BBL represents a bead base line. The bead baseline is a line that defines a rim diameter (see JATMA) of a rim (not shown) on which the tire 2 is mounted. A double-headed arrow H1 represents the height in the radial direction from the bead base line to the inner end 76 of the inner sidewall 28. A double-headed arrow H2 represents the height in the radial direction from the bead base line to the inner end 68b of the second filler 64b. A double-headed arrow H3 represents the height in the radial direction from the bead base line to the outer end 78 of the inner sidewall 28. A double-headed arrow H4 represents the height in the radial direction from the bead base line to the outer end 74 of the clinch 8.

  In the tire 2, the height H1 is 23 mm or less. By setting the height H1 to be equal to or less than 23 mm, the inner end 76 of the inner sidewall 28 is disposed at a position that fits within the flange of the rim to which the tire 2 is mounted. In the tire 2, the occurrence of loose starting from the inner end 76 of the inner sidewall 28 is effectively suppressed. The tire 2 is excellent in durability. From this viewpoint, the height H1 is more preferably 12 mm or less, and further preferably 10 mm or less. Since the inner end is preferably located on the inner side in the radial direction, the lower limit of the height H1 is 0 mm.

  In the tire 2, the inner end 76 of the inner sidewall 28 is located outside the inner end 68 b of the second filler 64 b, in other words, the inner end of the filler portion 26. The inner end 76 of the inner sidewall 28 does not protrude from the filler portion 26. Thereby, the distortion which arises in the inner end 76 of this inner side wall 28 is relieved effectively. In the tire 2, the occurrence of loose starting from the inner end 76 of the inner sidewall 28 is effectively suppressed. The tire 2 is excellent in durability. In this respect, the height H2 is preferably smaller than the height H1. More specifically, the difference (H1−H2) between the height H1 and the height H2 is preferably larger than 0 mm, and more preferably 3 mm or more. From the viewpoint that the inner side wall 28 can effectively contribute to alleviation of distortion generated between the filler portion 26 and the clinch 8, the difference (H1−H2) is preferably 18 mm or less, and more preferably 10 mm or less.

  In the tire 2, the ratio of the height H3 to the height H4 is 80% or more from the viewpoint that the inner sidewall 28 can effectively contribute to alleviation of distortion generated between the filler portion 26 and the clinch 8. Preferably, it is 95% or less. The tire 2 is excellent in durability.

  In FIG. 2, the double arrow T represents the thickness of the clinch 8. This thickness T is represented by the maximum thickness of the clinch 8. Reference numeral BG represents a position on the outer surface of the tire 2 corresponding to the upper surface 70 of the core 44 forming the bead 10. The symbol BT represents bead toe. A double arrow W represents the axial distance from the bead toe BT to the position BG. In this specification, this distance W is the reference width of the bead 10 portion of the tire 2.

  In the tire 2, the ratio of the thickness T to the reference width W is 34% or more and 50% or less. By setting this ratio to 34% or more, the clinch 8 can effectively contribute to alleviation of distortion generated at the inner end 76 of the inner sidewall 28. The clinch 8 can contribute to improvement of durability. In this respect, the ratio is more preferably equal to or greater than 37%. By setting this ratio to 50% or less, the thickness T of the clinch 8 is appropriately maintained. Since the portion of the bead 10 has an appropriate thickness, heat generation in this portion can be effectively suppressed. The tire 2 is excellent in durability. In this respect, the ratio is preferably equal to or less than 46%. In the tire 2 mounted on a truck, a bus or the like, the reference width W is set to 18 mm or more and 24 mm or less.

  In the present invention, the size and angle of each member 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.

  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 was LT245 / 75R16 120 / 116Q. The clinch thickness T was 9.0 mm. The reference width W of the bead portion of the tire was 23 mm. Therefore, the ratio of the thickness T to the reference width W was 39.1%. The radial height H1 from the bead base line to the inner edge of the inner sidewall was set to 12 mm. The radial height H2 from the bead base line to the inner end of the filler portion was 7 mm.

[Example 2-4 and Comparative Example 3]
Tires were obtained in the same manner as in Example 1 except that the thickness T was changed and the ratio T / W was changed as shown in Table 1 below.

[Comparative Example 4]
A tire was obtained in the same manner as in Example 1 except that the height H1 was as shown in Table 2 below.

[Examples 5-7 and Comparative Example 5]
A tire was obtained in the same manner as in Example 1 except that the height H1 and the height H2 were as shown in Table 2 below.

[Comparative Example 1-2]
A tire was obtained in the same manner as in Example 1 except that the thickness T was changed and the ratio T / W was as shown in Table 1 below, and the heights H1 and H2 were as shown in Table 1.

[durability]
The tire was incorporated into a regular rim (size = 7J), and the tire was filled with air to adjust the internal pressure to 550 kPa. This tire was mounted on a drum-type running test machine, and a longitudinal load of 27.04 kN was applied to the tire. This tire was run on a drum having a radius of 1.7 m at a speed of 20 km / h. The running time until the bead portion of the tire broke was measured. The results are shown in Tables 1 and 2 below as indices. A larger numerical value is preferable.

  As shown in Tables 1 and 2, 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 pneumatic tire described above can be applied to various vehicles.

DESCRIPTION OF SYMBOLS 2 ... Tire 4 ... Tread 6 ... Side wall 8 ... Clinch 10 ... Bead 12 ... Carcass 26 ... Filler part 28 ... Inner side wall 30 ... Chafer 44 ... Core 46 ... Apex 48a, 48b, 48c, 48 ... Ply 50a, 50b ... Main part 52a, 52b ... Folded part 64a, 64b ... Filler

Claims (2)

A tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from the end of the tread, and a pair of clinch each extending substantially inward in the radial direction from the end of the sidewall; A pair of beads each positioned axially inward of the clinch, a pair of fillers positioned between the bead and the clinch, and a pair of fillers positioned between the filler and the clinch, respectively. An inner sidewall, and a carcass spanned between one bead and the other bead along the inside of the tread and the sidewall;
The bead includes a core and an apex extending radially outward from the core;
The carcass has a ply,
The ply is folded around the core from the inside in the axial direction to the outside,
By this folding, the main part and the folding part are formed in this ply.
The filler is located outside the folded portion in the axial direction,
The radial height from the bead base line to the inner edge of the inner sidewall is 23 mm or less,
A pneumatic tire having a ratio of clinch thickness to a reference width of the bead portion of 34% or more and 50% or less. It further comprises a chafer folded around the bead from the inside in the axial direction to the outside,
This chafer consists of cloth and rubber impregnated in this cloth,
The pneumatic tire according to claim 1, wherein when the tire is incorporated in a rim, the chafer contacts the rim.

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