1 INNER MULTI-PIECE RIM Technical Field [0001] The present invention relates to an inner multi-piece rim for a dual wheel structure used for a construction vehicle and the like. Background [0002] FIG. 11 illustrates a dual wheel structure, which makes a tire T2 mounted onto an inner multi-piece rim 2 of a dual wheel structure removable from a rim base 2a of the inner multi-piece rim 2 without removing a rim base 1 a of an outer multi-piece rim 1 of the dual wheel structure from a hub 3, when a tire T1 mounted onto the outer multi-piece rim 1 has been removed from the rim base 1 a of the outer multi-piece rim 1. [0003] An outward end portion in an axial direction of the rim base la, that is, an outboard end portion in a width direction of a vehicle, of the outer multi-piece rim 1 is formed in a form of an outer gutter lb having a lock-ring groove and an O-ring groove. An outer lock-ring 4a and an outer bead seat band 5a are mounted onto the outer gutter lb. An outer side ring 6a is mounted onto the outer bead seat band 5a. An outer 0 ring 7a is disposed between the outer gutter lb and the outer bead seat band 5a. An inward end portion in the axial direction of the rim base la, that is, an inboard end portion in the width direction of the vehicle, of the outer multi-piece rim 1 is formed in a form of an inner gutter lc having a lock-ring groove and an O-ring groove. An inner lock-ring 4b and an inner bead seat band 5b are mounted onto the inner gutter 1c. An inner side ring 6b is mounted onto the inner bead seat band 5b. An inner O-ring 7b is disposed between the inner gutter Ic and the inner bead seat band 5b. [0004] An outward end portion in an axial direction of the rim base 2a, that is, an outboard end portion in a width direction of a vehicle, of the inner multi-piece rim 2 is formed in a form of an outer gutter 2b having a lock-ring groove and an O-ring groove. An outer lock-ring 4a' and an outer bead seat band 5a' are mounted onto the outer gutter 2b. An outer side ring 6a' is mounted onto the outer bead seat band 5a'. An outer O-ring 7a' is disposed between the outer gutter 2b and the outer bead seat band 5a'. An inward end portion in the axial direction of the rim base 2a, that is, an inboard end 2 portion in the width direction of the vehicle, of the inner multi-piece rim 2 is formed in a form of a back flange 2c. Only an inner side ring 6b' is mounted onto the back flange 2c. The outer lock-ring 4a', the outer bead seat band 5a', the outer side ring 6a', the outer O-ring 7a' and the inner side ring 6b' of the inner multi-piece rim 2 are the same configuration as the outer lock-ring 4a, the outer bead seat band 5a, the outer side ring 6a, the outer O-ring 7a and the inner side ring 6b of the outer multi-piece rim 1, respectively. [0005] As illustrated in FIG. 12, when the tire T1 mounted on the outer multi-piece rim 1 and the tire T2 mounted on the inner multi-piece rim 2 are removed from the rim base l a and the rim base 2a, respectively, the tire TI is removed in a form of an assembly with the outer bead seat band 5a, the outer side ring 6a, the inner bead seat band 5b and the inner side ring 6b, and the tire T2 is removed in a form of an assembly with the outer bead seat band 5a' and the outer side ring 6a'. Therefore, the assembly structure of the tire T2 is different from the assembly structure of the tire T1. [0006] However, there are the following problems with the conventional inner multi piece rim: As described above, the assembly structure of the tire T2 is different from the assembly structure of the tire TI. Thus, when the tires TI and T2 are removed from the respective rim bases and then the tires T1 and T2 are exchanged each other (that is, when the tire TI is mounted onto the rim base 2a of the inner multi-piece rim 2 and the tire T2 is mounted onto the rim base la of the outer multi-piece rim 1), the inner bead seat band 5b and the inner side ring 6b are required to be removed from the tire TI and the inner bead seat band 5b and then the inner side ring 6b are required to be mounted onto the tire T2. This needs a relatively large amount of work and period of time. Further, between when the tire TI is exchanged with a spare tire and when the tire T2 is exchanged with the spare tire, assembly states of the spare tires are to be different from each other. This also needs a relatively large amount of work amount and period of time. Related Art Document Patent Document 3 [0007] Document 1: Patent Publication No. US 2002/0149256 Object of the Invention [0008] It is the object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages. Summary of the Invention [0009] The present invention provides an inner multi-piece rim comprising: (a) a rim base including a central portion, an outer gutter and an inner gutter, the outer gutter being located outward of the central portion in an axial direction of the rim, which corresponds to, outboard of the central portion in a width direction of a vehicle, and an inner gutter being located inward of the central portion in the axial direction of the rim, which corresponds to, inboard of the central portion in the width direction of the vehicle, the central portion having a radially inside surface, the outer gutter having an outer lock-ring groove, the inner gutter having a radially outside surface and a radially inside surface; (b) an outer lock-ring mounted at the outer lock-ring groove; (c) an outer bead seat band mounted onto the outer gutter; (d) an outer O-ring disposed between the outer gutter and the outer bead seat band; (e) an outer side ring mounted onto the outer bead seat band; (f) an inner bead seat band mounted onto the inner gutter; (g) an inner O-ring disposed between the inner gutter and the inner bead seat band; and (h) an inner side ring mounted onto the inner bead seat band, wherein the radially outside surface of the inner gutter includes: a horizontal surface, an inclined surface located inward of the horizontal surface in the axial direction of the rim and inclined in an axially inward and radially outward direction of the rim so that the inclined surface contacts the inner bead seat band and receives an axial force loaded onto the inclined surface from the inner bead seat band, and an O-ring axially supporting surface for supporting the inner O-ring from an inward side of the inner O-ring in the axial direction of the rim, wherein the O-ring axially supporting surface is located between an axially inward end of the horizontal surface and an axially inward end of the inclined surface in the axial direction of the rim, and at least a portion of the O-ring axially supporting surface is located radially outside the horizontal surface in a radial direction of the rim, 4 wherein the radially inside surface of the inner gutter has the same diameter as the radially inside surface of the central portion, wherein the radially outside surface of the inner gutter further includes an 0-ring radially supporting surface for supporting the inner 0-ring from a radial inside of the inner O-ring in the radial direction of the rim, wherein the inner bead seat band includes a contact portion contacting the horizontal surface of the inner gutter, a first inclined surface extending in the axially inward and radially outward direction of the rim from the contact portion and a second inclined surface connected to the first inclined surface and contacting the inclined surface of the inner gutter, wherein the second inclined surface extends in the axially inward and radially outward direction of the rim at an angle larger than an inclination angle of the first inclined surface, and wherein the inner O-ring is pushed and deformed by the first inclined surface, the O-ring axially supporting surface and the O-ring radially supporting surface so that a clearance between the inner gutter and the inner bead seat band is sealed. Preferably, the O-ring axially supporting surface is connected to the inclined surface. Preferably, the outer side ring has an axially inward surface and the inner side ring has an axially outward surface, and wherein a thickness of the rim base at a portion being located inward of the axially inward surface of the outer side ring in the axial direction of the rim and located outward of the axially outward surface of the inner side ring in the axial direction of the rim is constant. [0010] According to an inner multi-piece rim in an embodiment of the present invention, the following technical advantages can be obtained: Since the inner multi-piece rim includes the outer bead seat band, the outer side ring, the inner bead seat band and the inner side ring, when a tire is removed from the rim base of the inner multi-piece rim, the tire can be removed in a form of an assembly with the outer bead seat band, the outer side ring, the inner bead seat band and the inner side ring. Thus, the assembly structure of the tire removed from the rim base of the inner multi-piece rim can be the same as an assembly structure of a tire removed from a rim base of an outer multi-piece rim. Therefore, when the tire removed from the rim base of the inner multi-piece rim and the tire removed from the rim base of the outer multi-piece rim are exchanged to each other, it is possible to change the 5 positions only, without changing each assembly structure. Further, between a case of exchanging the tire removed from the rim base of the inner multi-piece rim to a spare tire and a case of exchanging the tire removed from the rim base of the outer multi-piece rim to the spare tire, it is not necessary to change the assembly structure of the spare tire. As a result, it is possible to reduce an amount of work and a period of time required for exchanging tires, compared with the conventional tire. [0011] According to an inner multi-piece rim in an embodiment of the present invention, the following technical advantages can be further obtained: The radially outside surface of the inner gutter includes the O-ring axially supporting surface for supporting the inner O-ring from an inward side of the inner O-ring in the axial direction of the rim, and at least a portion of the O-ring axially supporting surface is located radially outside the horizontal surface in the radial direction of the rim. Thus, when an O-ring groove is provided at the inner gutter, a depth of the O-ring groove can be small, compared with a case where an entirety of the O-ring axially supporting surface is located radially inside the horizontal surface. Therefore, a strength of the inner gutter can be ensured, even in a case where (i) an inside surface of the inner gutter is larger in diameter than an inside surface of the outer gutter and (ii) the inside surface of the inner gutter is the same in diameter as an inside surface of the central portion of the rim base or is smaller in diameter than the inside surface of the central portion of the rim base to an extent that the rim base can be fitted to a vehicle hub without interfering with the hub. [0012] The radially outside surface of the inner gutter includes the inclined surface located axially inward of the horizontal surface, inclined in a radially outward and axially inward direction of the inner multi-piece rim and contacting the inner bead seat band, thereby receiving an axial force loaded on the inclined surface from the inner bead seat band. Thus, it is unnecessary to provide a lock-ring (an inner lock-ring) for receiving an axial force from the inner bead seat band. Therefore, unlike a case where the inner lock-ring is required to be provided and a slit for enabling the inner lock-ring to be removed from or fitted to the rim base is provided at the inner lock-ring, the inner O-ring will not be deformed into the slit, whereby the inner O-ring is prevented from being damaged so that air is prevented from leaking. Therefore, unlike the case where the inner lock-ring is provided, a disposition of the inner 0 ring is not influenced and restricted by the inner lock-ring. As a result, the O-ring axially supporting surface can be located between the axially inward end of the horizontal surface and the axially inward end of the inclined surface.
6 [0013] According to an inner multi-piece rim in an embodiment of the present invention, the following technical advantages can be obtained: Since the O-ring axially supporting surface is connected to the inclined surface, the O-ring axially supporting surface can be formed relatively easily by, for example, recessing a portion of the inclined surface in the axially inward direction of the inner multi-piece rim. [0014] According to an inner multi-piece rim in an embodiment of the present invention, the inner O-ring is disposed in a triangular cross-sectional space defined by the at least one of the first inclined surface and the second inclined surface of the inner bead seat band, the O-ring axially supporting surface and the O-ring radially supporting surface, so that the inner O-ring is deformed in a radial direction and an axial direction of the inner multi-piece rim. Thus, when the inner multi-piece rim is subjected to a load and when the inner bead seat band and the rim base are elastically deformed whereby the triangular cross-sectional space is deformed, the inner O-ring can easily follow the deformation. Therefore, a seal effect of the inner O-ring is highly ensured. Brief Description of Drawings [0014a] Preferred embodiments of the invention will be described hereinafter, by way of examples only, with reference to the accompanying drawings: [0015] FIG. 1 is a cross-sectional view of a dual wheel structure including an inner multi-piece rim according to a first embodiment of the present invention. FIG. 1 is applicable to second to sixth embodiments of the present invention by changing a configuration of an inner O-ring supporting portion of the inner multi-piece rim is reversed. FIG. 2 is a partial, enlarged cross-sectional view of an inner gutter and its vicinity of the inner multi-piece rim according to the first embodiment of the present invention. FIG. 2 is applicable to the second to sixth embodiments of the present invention by changing a configuration of an inner O-ring supporting portion of the inner multi-piece 7 rim. FIG. 3 is a partial, enlarged cross-sectional view of an outer gutter and its vicinity of the inner multi-piece rim according to the first embodiment of the present invention. FIG. 3 is applicable to the second to sixth embodiments of the present invention. FIG. 4 is a cross-sectional view of the dual wheel structure including the inner multi piece rim according to the first embodiment of the present invention, where tires are removed from the inner multi-piece rim and an outer multi-piece rim, respectively. FIG. 4 is applicable to the second to sixth embodiments of the present invention by changing the configuration of the inner O-ring supporting portion of the inner multi piece rim. FIG. 5 is a partial, enlarged cross-sectional view of an O-ring axially supporting surface and its vicinity of the inner gutter of the inner multi-piece rim according to the first embodiment of the present invention. FIG. 6 is a partial, enlarged cross-sectional view of an O-ring axially supporting surface and its vicinity of an inner gutter of an inner multi-piece rim according to the second embodiment of the present invention. FIG. 7 is a partial, enlarged cross-sectional view of an O-ring axially supporting surface and its vicinity of an inner gutter of an inner multi-piece rim according to the third embodiment of the present invention. FIG. 8 is a partial, enlarged cross-sectional view of an O-ring axially supporting surface and its vicinity of an inner gutter of an inner multi-piece rim according to the fourth embodiment of the present invention. FIG. 9 is a partial, enlarged cross-sectional view of an O-ring axially supporting surface and its vicinity of an inner gutter of an inner multi-piece rim according to the fifth embodiment of the present invention. FIG. 10 is a partial, enlarged cross-sectional view of an O-ring axially supporting 8 surface and its vicinity of an inner gutter of an inner multi-piece rim according to the sixth embodiment of the present invention. FIG. 11 is a cross-sectional view of a dual wheel structure including a conventional inner multi-piece rim. FIG. 12 is a cross-sectional view of the dual wheel structure including the conventional inner multi-piece rim, where tires are removed from the inner multi-piece rim and an outer multi-piece rim, respectively. Detailed Description of the Preferred Embodiments [0016] FIGS. 1 - 5 illustrate an inner multi-piece rim according to a first embodiment of the present invention. FIG. 6 illustrates an inner multi-piece rim according to a second embodiment of the present invention. FIG. 7 illustrates an inner multi-piece rim according to a third embodiment of the present invention. FIG. 8 illustrates an inner multi-piece rim according to a fourth embodiment of the present invention. FIG. 9 illustrates an inner multi-piece rim according to a fifth embodiment of the present invention. FIG. 10 illustrates an inner multi-piece rim according to a sixth embodiment of the present invention. In the drawings, "IN" shows an axially inward direction of a rim, which corresponds to, an inboard direction of the rim in a width direction of a vehicle, and "OUT" shows an axially outward direction of the rim, which corresponds to, an outboard direction of the rim in the width direction of the vehicle. Portions common to all embodiments of the present invention are denoted with the same reference numerals throughout the all embodiments of the present invention. First, portions common to the all embodiments of the present invention will be explained. [0017] As illustrated in FIG. 1, an inner multi-piece rim 20 according to any embodiment of the present invention is used for construction vehicles, etc. and has a plurality of pieces. The inner multi-piece rim 20 is used for an inner wheel (which is an inboard wheel in a width direction of a vehicle) of a dual wheel structure (a rear dual wheel structure). Alternatively, the inner multi-piece rim 20 may be used for a front wheel which is not a dual wheel structure. In the embodiments of the present invention described below, a case where the inner multi-piece rim 20 is used for the 9 inner wheel of the dual wheel structure will be explained. An outer multi-piece rim 10 which is an outboard wheel of the dual wheel structure (rear dual wheel structure) is disposed outboard of the inner multi-piece rim 20 in the width direction of the vehicle. [0018] The outer multi-piece rim 10 includes a rim base 11, an outer lock-ring 12, an outer bead seat band 13, an outer O-ring 14, an outer side ring 15, an inner lock-ring 16, an inner bead seat band 17, an inner O-ring 18 and an inner side ring 19. [0019] The rim base 11 is formed separately from a hub 30 of the vehicle and is fixed to the hub 30. An inside diameter of the rim base 11 is larger than a diameter of an outside surface of a portion of the hub 30 at which the rim base 11 is disposed. The rim base 11 includes a central portion 11a, an outer gutter 11b and an inner gutter 1Ic. The outer gutter 11 b is located axially outward of the central portion 1 la, i.e., outboard of the central portion 11 a in the width direction of the vehicle. The inner gutter 11 c is located axially inward of the central portion 11a, i.e., inboard of the central portion l Ia in the width direction of the vehicle. The outer gutter 1Ib and the inner gutter i1c may be formed integral with the central portion Ila. Alternatively, the outer gutter 11b and the inner gutter I1c may be formed separately from the central portion la and then may be fixed to the central portion Ila by welding. A radially outside surface (hereinafter, outside surface) 11d of the outer gutter 11 b and an outside surface I1e of the inner gutter 11 c are connected to an outside surface Ilk of the central portion I la. A radially inside surface (hereinafter, inside surface) 11 f of the outer gutter I 1b and an inside surface I 1g of the inner gutter 11 c are connected to an inside surface 11 h of the central portion I 1a. The outside surface I1d of the outer gutter 11 b and the outside surface I1e of the inner gutter I 1c have a lock-ring groove and an 0 ring groove which are concave radially inwardly, respectively. The inside surface l1 f of the outer gutter I Ib includes a portion IIi located radially inner than the inside surface 11 h of the central portion l la. The inside surface 11 g of the inner gutter II c includes a portion 11 j located radially inner than the inside surface I 1h of the central portion 11 a. The outside surface 11d of the outer gutter I 1b and the outside surface I1e of the inner gutter I 1c are the same (or substantially the same) in diameter to each other except the lock-ring grooves and the O-ring grooves. The outside surface 11k of the central portion 11 a has the same (or substantially the same) diameter as the 10 outside surface 11d of the outer gutter I 1b and the outside surface I1e of the inner gutter 1 Ic except the lock-ring grooves and the O-ring grooves. However, the outside surface I 1k of the central portion l la may be smaller in diameter than the outside surface I 1d of the outer gutter I 1b and the outside surface I1e of the inner gutter II c except the lock-ring grooves and the O-ring grooves. The outside surface I 1d of the outer gutter 11 b and the outside surface I1e of the inner gutter 11 c except the lock-ring grooves and the O-ring grooves may be larger in diameter than the outside surface 11k of the central portion Ila to an extent that all the bead seat bands 13, 17, 23 and 26 can slide without interfering with the surfaces. [0020] The outer lock-ring 12 having at least one slit in a circumferential direction is mounted in the lock-ring groove of the outer gutter lb. The outer bead seat band 13 which is axially supported by the outer lock-ring 12 is mounted onto the outer gutter 1lb. The outer side ring 15 which is axially supported by the outer bead seat band 13 is mounted onto the outer bead seat band 13. [0021] The outer O-ring 14 is disposed between the outer gutter 11 b and the outer bead seat band 13. A clearance between the outer gutter 1Ib and the outer bead seat band 13 is sealed by the outer O-ring 14. The outer O-ring 14 may be a belt ring capable of sealing. The outer O-ring 14 is disposed at a position axially inwardly spaced from the outer lock-ring 12 in order that the outer O-ring 14 is prevented from interfering with an edge of the slit of the outer lock-ring 12 and being damaged. The outer O-ring 14 is mounted in the O-ring groove of the outer gutter 1lb. The outer O ring 14 is supported in the axially outward direction and the axially inward direction of the outer multi-piece rim by a surface of the O-ring groove of the outer gutter 11b. [0022] The inner lock-ring 16 having at least one slit in a circumferential direction is mounted in the lock-ring groove of the inner gutter 1Ic. The inner bead seat band 17 axially supported by the inner lock-ring 16 is mounted onto the inner gutter 11 c. The inner side ring 19 axially supported by the inner bead seat band 17 is mounted onto the inner bead seat band 17. [0023] The inner O-ring 18 is disposed between the inner gutter 1Ic and the inner bead seat band 17. A clearance between the inner gutter 1Ib and the inner bead seat band 11 17 is sealed by the inner O-ring 18. The inner O-ring 18 may be a belt ring capable of sealing. The inner O-ring 18 is disposed at a portion axially outwardly spaced from the inner lock-ring 16 in order that the inner O-ring 18 is prevented from interfering with an edge of slit of the inner lock-ring 16 and being damaged. The inner O-ring 18 is mounted in the O-ring groove of the inner gutter 11 c. The inner 0 ring 18 is supported in the axially inward direction and the axially outward direction of the outer multi-piece rim by a surface of the O-ring groove of the inner gutter 11 c. [0024] Each of the rim base 11, the outer bead seat band 13, the outer O-ring 14, the outer side ring 15, the inner bead seat band 17, the inner O-ring 18 and the inner side ring 19 is continuous in a circumferential direction. Each of the outer lock-ring 12 and the inner lock-ring 16 has at least one slit in the circumferential direction so that mounting and removing of the lock-rings onto and from the rim base is possible. Each of the outer lock-ring 12 and the inner lock-ring 16 has opposite ends opposing each other and spaced from each other in the circumferential direction at the slit. [0025] The inner multi-piece rim 20 according to the embodiment of the present invention includes a rim base 21, an outer lock-ring 22, an outer bead seat band 23, an outer O-ring 24, an outer side ring 25, an inner bead seat band 26, an inner O-ring 27 and an inner side ring 28. [0026] The rim base 21 is formed separately from the hub 30 of the vehicle and is fixed to the hub 30. An diameter of the rim base 21 is larger than a diameter of an outside surface of a portion of the hub 30 at which the rim base 21 is disposed. The rim base 21 includes a central portion 21a, an outer gutter 21b and an inner gutter 21c. The outer gutter 21b is located axially outward of the central portion 21a, i.e., outboard of the central portion 21a in the width direction of the vehicle. The inner gutter 21c is located axially inward of the central portion 21a, i.e., inboard of the central portion 21a in the width direction of the vehicle. The outer gutter 21b and the inner gutter 21c may be formed integral with the central portion 21a. Alternatively, as illustrated in FIGS. 2 and 3, the outer gutter 21b and the inner gutter 21c may be formed separately from the central portion 21 a and then may be fixed to the central portion 21a by welding.
12 [0027] As illustrated in FIG. 1, an outside surface 21 d of the central portion 21 a of the rim base 21 of the inner multi-piece rim 20 may be the same (or substantially the same) diameter as the outside surface I1k of the central portion 11 a of the rim base 11 of the outer multi-piece rim 10. Alternatively, the outside surface 21d of the central portion 21 a of the rim base 21 may be larger or smaller than the outside surface I1k of the central portion 11 a of the rim base 11 to an extent that the inner bead seat bands 17 and 26 can slide without interfering with the outside surfaces Ilk and 21a. At least one of the outside surface 21d of the central portion 21a of the inner multi-piece rim 20 and the outside surface 11k of the central portion 11 a of the outer multi-piece rim 10 may be smaller in diameter than the outside surfaces I1d, I1e, 21 f of the gutters I 1b, 11 c, 21 b and a horizontal surface 21 q (which will be post-explained) of the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20. An inside surface 21e of the central portion 21a of the rim base 21 of the inner multi piece rim 20 may be the same (or substantially the same) in diameter as the inside surface llh of the central portion lla of the rim base II of the outer multi-piece rim 10. Alternatively, the inside surface 21e of the central portion 21a may be larger in diameter than the inside surface 11 h of the central portion l la, so long as a strength of the rim base 21 can be ensured. [0028] As illustrated in FIG. 3, the outside surface 21f of the outer gutter 21b is connected to the outside surface 21d of the central portion 21a. The outside surface 21f of the outer gutter 21b has an outer lock-ring groove 21k and an outer O-ring groove 21m which are radially inwardly concave. The outside surface 21f of the outer gutter 21b has the same (substantially the same) diameter as the outside surface 21d of the central portion 21a, except the outer lock-ring groove 21k and the outer 0 ring groove 21m. However, the outside surface 21d of the central portion 21a may be smaller in diameter than the outside surface 21 f of the outer gutter 21 b except the outer lock-ring groove 21k and the outer O-ring groove 21m. The outside surface 21f of the outer gutter 21b except the outer lock-ring groove 21k and the outer O-ring groove 21m may be larger in diameter than the outside surface 21d of the central portion 21a to an extent that all the bead seat bands 13, 17, 23 and 26 can slide without interfering with the outside surface 21f. An inside surface 21i of the outer gutter 21b is connected to the inside surface 21e of the central portion 21 a. The inside surface 21i of the outer gutter 21b includes a portion 21j located radially inner than the inside 13 surface 21e of the central portion 21a. [0029] The outer lock-ring 22 having at least one slit in a circumferential direction is mounted in the outer lock-ring groove 21k of the outer gutter 21b. The outer bead seat band 23 axially supported by the outer lock-ring 22 is mounted onto the outer gutter 21b. The outer side ring 25 axially supported by the outer bead seat band 23 is mounted onto the outer bead seat band 23. [0030] The outer O-ring 24 is disposed between the outer gutter 21b and the outer bead seat band 23. A clearance between the outer gutter 21b and the outer bead seat band 23 is sealed by the outer O-ring 24. The outer O-ring 24 may be a belt ring capable of sealing. The outer O-ring 24 is disposed at a position axially inwardly spaced from the outer lock-ring 22 in order that the outer O-ring 24 is prevented from interfering with an edge of the slit of the outer lock-ring 12 and being damaged. The outer O-ring 24 is mounted in the outer O-ring groove 21m. The outer O-ring 24 is supported from the axially outward direction and the axially inward direction of the inner multi-piece rim by a surface of the outer O-ring groove 21m of the outer gutter 21b. [0031] As illustrated in FIG. 2, an inside surface 21n of the inner gutter 21c is connected to the inside surface 21e of the central portion 21a. The inside surface 21n of the inner gutter 21c has the same (substantially the same) diameter as the inside surface 21e of the central portion 21a. However, the inside surface 21n of the inner gutter 21c may be smaller in diameter than the inside surface 21e of the central portion 21a so long as the rim base 21 can be fitted to the hub 30. The inside surface 21n of the inner gutter 21c may be larger in diameter than the inside surface 21i of the outer gutter 21b except the portion 21j. [0032] An outside surface 21p of the inner gutter 21c includes the horizontal surface 21q, an inclined surface 21r, an O-ring axially supporting surface 21s and an O-ring radially supporting surface 21w. [0033] The horizontal surface 21q is connected to the outside surface 21d of the central portion 21a. The horizontal surface 21q has the same (or substantially the 14 same) diameter as the outside surface 21d of the central portion 21a. However, the outside surface 21d of the central portion 21a may be smaller in diameter than the horizontal surface 21q. The horizontal surface 21q may be larger in diameter than the outside surface 21d of the central portion 21a so long as the bead seat bands 17, 26 can slide. The horizontal surface 21q is the same (substantially the same) in diameter as the outside surface 21f of the outer gutter 21b. [0034] The inclined surface 21r is a surface inclined in a radially outward and axially inward direction of the inner multi-piece rim. At least a portion of the inclined surface 21r is located axially inward of the horizontal surface 21q. The inclined surface 21r is located radially outer than (radially outside) the horizontal surface 21q. The inclined surface 21r is caused to contact a second inclined surface 26a formed at the inner bead seat band 26, thereby receiving an axial force loaded onto the inclined surface 21r from the inner bead seat 26. [0035] As illustrated in FIG. 5, the inner O-ring 27 is supported by the O-ring axially supporting surface 21s from an axially inward side of the inner O-ring 27. The 0 ring axially supporting surface 21s is located between an axially inward end 21t of the horizontal surface 21q and an axially inward end 21u of the inclined surface 21r (including at any one of the ends 21t and 21u). At least a portion of the O-ring axially supporting surface 21s is located outside the horizontal surface 21q in the radial direction of the rim. The 0-ring axially supporting surface 21s may be (i) a flat surface (i.e., as illustrated in FIG. 5, a straight surface in cross section), (ii) a surface having one or more bent portions, (iii) a curved surface or (iv) a composite surface of two or more of these surfaces. The O-ring axially supporting surface 21s is connected to the inclined surface 21r. [0036] The O-ring radially supporting surface 21w is located axially outward of the 0 ring axially supporting surface 21s. The inner O-ring 27 is supported by the O-ring radially supporting surface 21w from a radially inside of the inner 0-ring. The O ring radially supporting surface 21w may be (i) a flat surface (i.e., as illustrated in FIG. 5, a straight surface in cross section), (ii) a surface having one or more bent portions, (iii) a curved surface or (iv) a composite surface of two or more these surfaces. The O-ring radially supporting surface 21w is connected to an axially outward end of the 15 O-ring axially supporting surface 21s. [0037] As illustrated in FIG.2, the inner bead seat band 26 which is axially supported by the inclined surface 21r is mounted onto the inner gutter 21c. The inner side ring 28 which is axially supported by the inner bead seat band 26 is mounted onto the inner bead seat band 26. The inner bead seat band 26 includes a first inclined surface 26b and a second inclined surface 26a. The first inclined surface 26b extends in a radially outward and axially inward direction of the inner multi-piece rim from a contact portion 26c contacting the horizontal surface 21q of the inner gutter 21c. The second inclined surface 26a is connected to the first inclined surface 26b and contacts the inclined surface 21 r of the rim base 21. [0038] The inner O-ring 27 is disposed between the inner gutter 21c and the inner bead seat band 26 so that a clearance between the inner gutter 21c and the inner bead seat band 26 is sealed by the inner O-ring 27. The inner O-ring 27 may be a belt ring capable of sealing. As illustrated in FIGS. 5-7, 9 and 10, in a case where a space between the inner gutter 21c and the inner bead seat band 26 is small, a groove 21v causing the space between the inner gutter 21c and the inner bead seat band 26 to be enlarged may be formed at the inner gutter 21c. A groove (not shown) causing the space between the inner gutter 21c and the inner bead seat band 26 to be enlarged may be formed not only at the inner gutter 21c but also at the inner bead seat band 26. The groove 21v may be provided (i) between the horizontal surface 21q and the inclined surface 21r in an axial direction of the inner multi-piece rim as illustrated in FIGS. 5-7, (ii) between the horizontal surface 21q and the inclined surface 21r in a radial direction of the inner multi-piece rim as illustrated in FIG. 9 or (iii) at an intermediate portion of the inclined surface 21r. The inner O-ring 27 includes a portion which is located outside the horizontal surface 21q in the radial direction of the inner multi-piece rim and which is supported by the O-ring axially supporting surface 21s from an axial inside of the inner O-ring. The inner O-ring 27 is supported by the O-ring radially supporting surface 21w from a radial inside of the inner 0-ring. [0039] Each of the rim base 21, the outer bead seat band 23, the outer O-ring 24, the 16 outer side ring 25, the inner bead seat band 26, the inner O-ring 27 and the inner side ring 28 is continuous in a circumferential direction. The outer lock-ring 22 has at least one slit in a circumferential direction so that the outer O-ring can be removed from and fitted to the rim base 21. The outer lock-ring 22 has opposite ends opposing each other in the circumferential direction at the slit. [0040] As illustrated in FIG. 1, the outer lock-ring 22, the outer bead seat band 23, the outer side ring 25 and the outer O-ring 24 of the inner multi-piece rim 20 are the same in configuration as the outer lock-ring 12, the outer bead seat band 13, the outer side ring 15 and the outer O-ring 14 of the outer multi-piece rim 10, respectively. The inner bead seat band 26 and the inner side ring 28 of the inner multi-piece rim 20 are the same in configuration as the inner bead seat band 17 and the inner side ring 19 of the outer multi-piece rim 10, respectively. [0041] Next, operation and technical advantages of the above structures common to all of the embodiments of the present invention will be explained. (A-I) The outside surface 11d of the outer gutter 1Ib and the outside surface I1e of the inner gutter 11 c of the rim base 11 of the outer multi-piece rim 10 are the same in diameter to each other except the lock-ring grooves and the O-ring grooves which are radially inwardly concave. The outside surface I1d and the outside surface 11e are the same in diameter as the outside surface 11k of the central portion 11a or are larger in diameter than the outside surface I1k of the central portion I 1a to an extent that all the bead seat bands 13, 17, 23 and 26 can slide without interfering with the outside surfaces I1d and I1e. Therefore, by removing the outer lock-ring 12 from the rim base 11, a tire T10 mounted onto the outer multi-piece rim 10 can be removed from the rim base 11 without removing the rim base II from the hub 30. [0042] (A-2) The outside surface 21f of the outer gutter 21b and the horizontal surface 21q of the outside surface 21p of the inner gutter 21c, of the rim base 21 of the inner multi-piece rim 20 are the same in diameter to each other except the outer lock-ring groove 21k and the outer O-ring groove 21m which are radially inwardly concave. The outside surface 21 f and the horizontal surface 21 q are the same in diameter as the outside surface 21d of the central portion 21a or are larger in diameter than the outside surface 21d of the central portion 21a to an extent that all the bead seat bands 13, 17, 17 23, 26 can slide without interfering with the outside surface 21f and the horizontal surface 2lq. Therefore, by removing the outer lock-ring 22 from the rim base 21, a tire T20 mounted onto the inner multi-piece rim 20 can be removed from the rim base 21. [0043] (A-3) The outside surface I1d of the outer gutter 1lb and the outside surface lIe of the inner gutter 11 c, of the rim base 11 of the outer multi-piece rim 10 are the same in diameter to each other except the lock-ring grooves and the O-ring grooves. The outside surface 11d of the outer gutter 11 b and the outside surface I1e of the inner gutter 11 c, of the rim base II of the outer multi-piece rim 10 are the same in diameter as the outside surface I1k of the central portion 11 a or are larger in diameter than the outside surface I 1k of the central portion I 1a to an extent that all the bead seat bands 13, 17, 23, 26 can slide without interfering with the outside surfaces 11d and I1e. The outside surface 21d of the central portion 21a of the rim base 21 of the inner multi-piece rim 20 is (i) the same in diameter as the outside surface I1k of the central portion 11a of the rim base II of the outer multi-piece rim 10, (ii) larger in diameter than the outside surface I1k of the central portion 11 a to an extent that the bead seat bands 17 and 26 can slide without interfering withe the outside surface 21d, or (iii) smaller in diameter than the outside surface I1k of the central portion I a. The outside surface 21f of the outer gutter 21b and the horizontal surface 21q of the outside surface 21p of the inner gutter 21c, of the rim base 21 of the inner multi-piece rim 20 are the same in diameter to each other except the outer lock-ring groove 21k and the outer O-ring groove 21m. The outside surface 21f of the outer gutter 21b except the outer lock-ring groove 21k and the outer O-ring groove 21m is the same in diameter as the outside surface 21d of the central portion 21a of the rim base 21 of the inner multi-piece rim 20 or is larger in diameter than the outside surface 21d of the central portion 21a to the extent that all the bead seat bands 13, 17, 23, 26 can slide without interfering with the outside surface 21 f. The outside surface I1d of the outer gutter 1lb and the outside surface 1le of the inner gutter 1Ic of the outer multi-piece rim 10 except the lock-ring grooves and the O-ring grooves, the outside surface 21 f of the outer gutter 21b of the inner multi-piece rim 20 except the outer lock-ring groove 21k and the outer O-ring groove 21m, and the horizontal surface 21q of the inner multi-piece rim 20 are the same (substantially the same) in diameter. Therefore, as illustrated in FIG. 4, when the tire T10 mounted onto the outer multi- 18 piece rim 10 is removed from the rim base 11 of the outer multi-piece rim 10, the tire T20 mounted onto the inner multi-piece rim 20 can be removed from the rim base 21 of the inner multi-piece rim 20 without removing the rim base 11 of the outer multi piece rim 10 from the hub 30, by removing the inner lock-ring 16 of the outer multi piece rim 10 from the rim base 11 of the outer multi-piece rim 10 and removing the outer lock-ring 22 of the inner multi-piece rim 20 from the rim base 21 of the inner multi-piece rim 20. [0044] (B-1) The outer multi-piece rim 10 includes the outer bead seat band 13, the outer side ring 15, the inner bead seat band 17 and the inner side ring 19. Thus, the tire T10 mounted onto the outer multi-piece rim 10 is removed from the rim base 11 as an assembly with the outer bead seat band 13, the outer side ring 15, the inner bead seat band 17 and the inner side ring 19 by removing the outer lock-ring 12 from the rim base 11. [0045] (B-2) The inner multi-piece rim 20 includes the outer bead seat band 23, the outer side ring 25, the inner bead seat band 26 and the inner side ring 28. Thus, when the tire T20 is removed from the rim base 21 of the inner multi-piece rim 20, the tire T20 can be removed as an assembly with the outer bead seat band 23, the outer side ring 25, the inner bead seat band 26 and the inner side ring 28. Therefore, the assembly structure of the tire T20 removed from the rim base 21 of the inner multi piece rim 20 can be the same as the assembly structure of the tire T10 removed from the rim base 11 of the outer multi-piece rim 10. Therefore, when the tire T20 removed from the rim base 21 of the inner multi-piece rim 20 and the tire T10 removed from the rim base 11 of the outer multi-piece rim 10 are exchanged to each other, it is possible to exchange the positions without changing each assembly structure. Further, in a case of exchanging the tire T20 removed from the rim base 21 of the inner multi piece rim 20 to a spare tire and in a case of exchanging the tire T1O removed from the rim base 11 of the outer multi-piece rim 10 to the spare tire, it is not necessary to change the assembly structure of the spare tire. As a result, it is possible to reduce a work amount and time period required for exchanging tires compared with a conventional one. [0046] (C) The inside surface 21n of the inner gutter 21c of the rim base 21 of the 19 inner multi-piece rim 20 is larger in diameter than the hub 30. The inside surface 21n is the same diameter as the inside surface 21e of the central portion 21a or is smaller in diameter than the inside surface 21e of the central portion 21a to the extent that the rim base 21 can be fitted to the hub 30 without interfering with the hub. Therefore, the rim base 21 can be mounted onto the hub 30. [0047] (D) The outside surface 21p of the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20 includes the O-ring axially supporting surface 21s by which the inner O-ring 27 is supported from an axial inside of the inner multi-piece rim, and at least a portion of the O-ring axially supporting surface 21s is located radially outside the horizontal surface 21q. Thus, when the groove 21v for the O-ring 27 is provided at the inner gutter 21c, a depth of the groove 21v can be small compared with a case where an entirety of the O-ring axially supporting surface 21s is located radially inside the horizontal surface 21 q. Therefore, a strength of the inner gutter 21c can be ensured, even in a case where (i) the inside surface 21n of the inner gutter 21c is larger in diameter than the inside surface 21i of the outer gutter 21b except the portion 21j and (ii) the inside surface 21n of the inner gutter 21c is the same in diameter as the inside surface 21e of the central portion 21a or is smaller in diameter than the inside surface 21e of the central portion 21a to the extent that the rim base 21 can be fitted to the hub 30 without interfering with the hub. [0048] (E) The outside surface 21p of the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20 includes the inclined surface 21r located axially inward of the horizontal surface 21q, inclined in a radially outward and axially inward direction of the inner multi-piece rim and contacting with the inner bead seat band 26, whereby the inner bead seat band 26 is axially supported by the inclined surface 21r. Thus, the assembly of the tire T20 including the inner bead seat band 26 can be fitted onto the inner multi-piece rim 20 unlike a conventional one. Since it is unnecessary to provide a lock-ring for axially supporting the inner bead seat band 26 unlike the outer multi-piece rim 10, the O-ring axially supporting surface 21s can be located between the axially inward end 21t of the horizontal surface 21q and the axially inward end 21u of the inclined surface 21r. [0049] (F) Since the O-ring axially supporting surface 21s is connected to the inclined 20 surface 21r, the O-ring axially supporting surface 21s can be formed relatively easily by, for example, recessing a portion of the inclined surface 21r in the axially inward direction of the inner multi-piece rim. [0050] Next, portions unique to respective embodiments of the present invention will be explained. [First Embodiment] (FIGS. 1-5) As illustrated in FIG. 5, in the first embodiment of the present invention, the groove 21v is provided at the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20. Only a portion of the 0-ring axially supporting surface 21s is located radially outside the horizontal surface 21q. The 0-ring axially supporting surface 21s except a boundary with the groove 21v is a flat surface perpendicular to the axial direction of the inner multi-piece rim. [0051] The groove 21v is provided between the horizontal surface 21q and the inclined surface 21r in the axial direction of the inner multi-piece rim. The groove 21v is radially inwardly concave. The groove 21 v includes the 0-ring radially supporting surface 21w by which the inner O-ring 27 is supported from a radial inside of the 0 ring. Only a radially inner end portion of the inner O-ring 27 is located in the groove 21v. [0052] [Second Embodiment] (FIG. 6) In the second embodiment of the present invention, the groove 21v is provided at the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20. Only a portion of the O-ring axially supporting surface 21s is located radially outside the horizontal surface 21q. A configuration of a cross section of the O-ring axially supporting surface 21s except a boundary with the groove 21v is straight. The O-ring axially supporting surface 21s except the boundary with the groove 21v is an inclined surface (a conical surface) inclined in a radially outward and axially inward direction of the inner multi-piece rim. [0053] The groove 21v is located between the horizontal surface 21q and the inclined surface 21r in the axial direction of the rim. The groove 21v is radially inwardly concave. Only a radially inward end portion of the inner O-ring 27 is in the groove 21 21v. The groove 21v includes the O-ring radially supporting surface 21w by which the inner O-ring 27 is supported from a radial inside of the O-ring 27. An inclination angle of the O-ring axially supporting surface 21s is closer to a direction perpendicular to the axial direction of the inner multi-piece rim (larger) than an inclination angle of the inclined surface 21r. [0054] [Third Embodiment] (FIG. 7) In the third embodiment of the present invention, the groove 21v is provided at the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20. The groove 21v includes the 0-ring radially supporting surface 21w by which the inner 0-ring 27 is supported from a radial inside of the inner O-ring. Only a portion of the O-ring axially supporting surface 21s is located radially outside the horizontal surface 21q. The O-ring axially supporting surface 21s is a composite surface including a flat surface and a curved surface. An inclination angle of the flat surface is closer to a direction perpendicular to the axial direction of the inner multi-piece rim (larger) than an inclination angle of the inclined surface 21r. [0055] The groove 21v is located between the horizontal surface 21q and the inclined surface 21r in the axial direction of the inner multi-piece rim. The groove 21v is radially inwardly concave. Only a portion of the inner O-ring 27 in the radial and axial direction of the inner O-ring, located at the radially inner portion of the inner 0 ring, is received in the groove 21v. A portion of the horizontal surface 21q acts as the O-ring radially supporting surface 21w by which the inner 0-ring 27 is supported from a radial inside of the O-ring. [0056] [Fourth Embodiment] (FIG. 8) In the fourth embodiment of the present invention, no groove 21v is provided at the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20. An entirety of the 0-ring axially supporting surface 21s is located radially outside the horizontal surface 21q. The O-ring axially supporting surface 21s is a flat surface perpendicular to the axial direction of the inner multi-piece rim. Alternatively, as illustrated in FIG. 6, the O-ring axially supporting surface 21s may be an inclined surface inclined in a radially outward and axially inward direction of the inner multi-piece rim.
22 [0057] [Fifth Embodiment] (FIG. 9) In the fifth embodiment of the present invention, the groove 21v is located at the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20. An entirety of the 0 ring axially supporting surface 21 s is located radially outside the horizontal surface 21q. The O-ring axially supporting surface 21s is a composite surface including a flat surface and a curved surface. An inclination angle of the flat surface is closer to a direction perpendicular to the axial direction of the rim (larger) than an inclination angle of the inclined surface 21r. A portion of the horizontal surface 21q is the 0 ring radially supporting surface 21w by which the inner O-ring 27 is supported from a radially inside of the O-ring. The groove 21v includes the O-ring radially supporting surface 21w by which the inner O-ring 27 is supported from a radially inside of the 0 ring. [0058] The groove 21v is located between the horizontal surface 21q and the inclined surface 21r in the radial direction of the inner multi-piece rim. The groove 21v is axially inwardly concave. Only a radially inward end portion of the inner O-ring 27 is in the groove 21v. [0059] [Sixth Embodiment] (FIG. 10) In the sixth embodiment of the present invention, the groove 21v is provided at the inner gutter 21c of the rim base 21 of the inner multi-piece rim 20. An entirety of the O-ring axially supporting surface 21s is located radially outside the horizontal surface 21q. The O-ring axially supporting surface 21s is substantially a flat surface perpendicular to the axial direction of the inner multi-piece rim. Alternatively, as illustrated in FIG. 6, the O-ring axially supporting surface 21s may be an inclined surface. [0060] The groove 21v is provided at an intermediate (axially and radially intermediate) portion of the inclined surface 21r. The groove 21v is axially inwardly concave. The inner O-ring 27 contacts both of the first inclined surface 26b and the second inclined surface 26a of the inner bead seat band 26. Explanation of Reference Numerals [0061] 10 outer multi-piece rim 23 11 rim base of the outer multi-piece rim 12 outer lock-ring of the outer multi-piece rim 13 outer bead seat band of the outer multi-piece rim 14 outer O-ring of the outer multi-piece rim 15 outer side ring of the outer multi-piece rim 16 inner lock-ring of the outer multi-piece rim 17 inner bead seat band of the outer multi-piece rim 18 inner O-ring of the outer multi-piece rim 19 inner side ring of the outer multi-piece rim 20 inner multi-piece rim 21 rim base of the inner multi-piece rim 21a central portion of the rim base 21b outer gutter 21c inner gutter 21d radially outside surface of the central portion of the rim base 21e radially inside surface of the central portion of the rim base 21f radially outside surface of the outer gutter 21i radially inside surface of the outer gutter 21k outer lock-ring groove 21m outer O-ring groove 21n radially inside surface of the inner gutter 21p radially outside surface of the inner gutter 21q horizontal surface 21r inclined surface 21s O-ring axially supporting surface 21v groove 21w O-ring radially supporting surface 22 outer lock-ring of the inner multi-piece rim 23 outer bead seat band of the inner multi-piece rim 24 outer O-ring of the inner multi-piece rim 25 outer side ring of the inner multi-piece rim 26 inner bead seat band of the inner multi-piece rim 26a second inclined surface 26b first inclined surface 24 26c contact portion 27 inner O-ring of the inner multi-piece rim 29 inner side ring of the inner multi-piece rim 30 hub