WO2000024598A1

WO2000024598A1 - Vehicle wheel with anti-flattening means

Info

Publication number: WO2000024598A1
Application number: PCT/IB1999/001712
Authority: WO
Inventors: Rino Rossi
Original assignee: Rino Rossi
Priority date: 1998-10-23
Filing date: 1999-10-20
Publication date: 2000-05-04
Also published as: AU6116999A; IT1304231B1; ITBO980605A1; ITBO980605A0

Abstract

Wheel for a vehicle, comprising a tyre (40) in the form of a container made of elastic polymeric material comprising an external circumferential band (46) realising a tread (48) in contact with the roadway (18), a rim (22) having a circumferential surface (24) for supporting said tyre defining therewith a chamber (14) for the inflation of the tyre itself, and anti-flattening means (50) with circumferential development in the form of elastically yielding means supported by said rim and positioned inside said inflation chamber, between the circumferential surface of the rim that supports said tyre and said external circumferential band realising the tread of the tyre, to sustain said circumferential band in a flattened condition of the tyre itself, said anti-flattening means presenting a gradual and progressive elastic pliancy in the radial direction, being greater in the central area, where they also present a greater outer diameter, whereas in the lateral areas they present a lesser outer diameter and a lesser elastic pliancy.

Description

Vehicle Wheel with Anti-flattening Means

Technical Field

The present invention relates to a vehicle wheel provided with means that prevent the tyre from totally flattening.

Background Art

In a substantially known manner, the wheel of the aforesaid type essentially comprises a tyre in the form of a container made of elastic polymeric material comprising an outer circumferential portion realising a tread in contact with the roadway, a rim having a circumferential surface for supporting said tyre defining therewith an inflation chamber, and anti-flattening means with circumferential development supported by said rim and positioned, within said inflation chamber, between said rim and said outer circumferential band of the tyre, for sustaining the circumferential band itself in a flattened condition of the tyre itself. According to a known type, said anti-flattening means are provided elastically yielding in the radial direction and present a modest elastic pliability, such as to make the known wheel behave, when in the flattened condition, in a manner similar to that of a solid wheel.

Thus, whilst regularly inflated wheels are able considerably to dampen the repercussions from the impacts that are imparted by the irregularities and asperities present on the roadway, since the tyre can yield in the area in contact with said asperities, known types of the aforesaid type, like solid wheels, in a flattened condition are able to dampen such repercussions only to a minimal extend and induce a perpendicular upward motion or displacement of said wheel, rendering the travel of the vehicle irregular with the presence of undesired impacts and vibrations.

Disclosure of Invention

The present invention provides a wheel having the characteristics of claim 1. In particular a vehicle wheel, comprising a tyre in the form of a container made of elastic polymeric material comprising an outer circumferential band realising a tread in contact with the roadway, a rim having a circumferential surface for supporting said tyre defining therewith an inflation chamber of the tyre itself, and anti-flattening means with circumferential development in the form of elastically yielding means supported by said rim and positioned within said inflation chamber, between said circumferential surface of the rim which supports said tyre and said outer circumferential band realising the tread of the tyre, to sustain the same circumferential band in a flattened condition of the tyre itself, characterised in that said anti-flattening means present a gradual and progressive elastic pliability in the radial direction to a great degree in the central area, where they also present a greater outer diameter, whereas in the lateral areas they present a lesser outer diameter and a reduced elastic pliancy. Further features and technical advantages of the invention shall become more readily apparent in the detailed description that follows, made with reference to the accompanying drawings.

Description of the Drawings - Figure 1 schematically shows, in its entirety, a cross section view of a portion of wheel according to the present invention;

- Figures 2, 5, 7, 8 and 9 show cross section views of a portion of wheel according to different possible embodiments;

- Figure 3 shows a cross section view according to the embodiment of Figure 2 in a condition of regularly inflated tyre;

- Figure 4 shows a cross section view according to the embodiment of Figure 2 in a condition of flattened tyre;

- Figure 6 shows a perspective view of a detail according to the embodiment of Figure 5; - Figure 10 shows a cross section view of a further embodiment presenting some variations with respect to the embodiment of Figure 9.

Description of the Illustrative Embodiments

Figure 1 schematically shows a cross section of vehicle wheel 10 according to the present invention. The wheel 10 essentially comprises a tyre 40, of traditional form, in the form of a container made of elastic polymeric material, which comprises an outer circumferential band 46 in correspondence with whose external superficial portion is realised a realising a tread 48 in rolling contact with the roadway, and lateral bands 43, 44, extending inwards from opposite sides of said circumferential band, realising the side walls of the tyre, at whose ends they present keying edges or beads 41, 42.

The wheel 10 further presents a part 20 for supporting said tyre 40 comprising a radial portion or supporting disc 21, extending from the central hub of the wheel, which in turn supports a circumferential portion or rim 22.

Said rim 22 comprises a first and a second part 22' and 22", joined by appropriate screws, and presents a circumferential surface 24 for supporting the tyre 40 with cylindrical shape. The present rim does not present the traditional projection which serves to retain the outer edge 42 of the tyre in its seat and the traditional throat for mounting the tyre itself, thereby allowing to have inside the rim a useful space with a greater diameter Dl for the same keying diameter of the tyre.

Said circumferential surface 24 presents at the opposite extremities projecting lateral edges 27, 28 for coupling with the edges or beads 41,

42 of the tyre 40 and defines with the tyre itself a chamber 14 into which pressurised air is introduced for inflating the tyre itself.

In the present wheel, to prevent the tyre from totally flattening as a consequence of the lack of the regular inflation pressure, are provided, within said inflation chamber 14, between the circumferential surface 24 of the rim 22 which supports said tyre 40 and said outer circumferential band 46 of the tyre, elastically yielding means 50, supported by said circumferential surface 24, in such a way as to define anti-flattening means able to support said circumferential band 46 in a condition of flattened tyre, caused for instance by a puncture or by the bursting of the tyre, or by other events.

Said anti-flattening means 50 bear solidly on the circumferential surface 24 of the rim 22 only in the lateral areas 51, 52, whereas in the central area 54 under resting conditions a certain space HI always remains between said circumferential surface and said anti-flattening means.

In correspondence with the area bearing on the circumferential surface 24, said anti-flattening means 50 present a width equal to the internal space of the tyre 40, and thanks to their shape, bearing on the circumferential surface only in the lateral areas 51, 52 and suspended in the central area 54, under flattened tyre conditions by compressing they tend to widen and optimally guarantee that the edges or beads 41, 42 of the tyre retain their position bearing on the edges 27, 28 of the rim 22.

In the cross section view said anti-flattening means 50 presents an outer shape with an arched profile 56 in correspondence with the central portion and a profile substantially inclined at the sides; moreover, they present a greater height H3 in the central area, such as to be located in proximity with the circumferential band 46 of the tyre 40 under conditions of travel with the tyre regularly inflated, so that in the presence of marked irregularities on the roadway they come in contact with the circumferential band itself.

The width of said anti-flattening means is not and need not be constant over the entire height. The thickness H2 in the central area 54 is greater than the thickness H5, H6 of the respective lateral areas 51, 52. Said anti-flattening means 50, although formed by a single body, are essentially constituted by a first and a second elastically yielding component 60, 70 with different characteristics of radial pliancy; the first component 60, with a greater rigidity and hardly yielding under compression, bears solidly on the circumferential surface 24 in the lateral areas 51, 52, where it also presents a greater thickness, and works by flexion in correspondence with the central area 54 exploiting the space HI, whilst the second component 70 more elastic and yielding under compression is normally positioned in the outer part of said anti- flattening means 50, in such a way as to come in contact with the circumferential band 46 of the tyre 40, and is such as to present a lesser thickness in the lateral areas and a greater thickness in the central area, thereby allowing this invention to offer a high degree of elasticity.

Said components are defined by their characteristics and functions, and may in turn be replaced with one or more elements. The present invention offers advantages under all conditions of travel, in that even with the tyre regularly inflated in case of insidious localised stresses due to a particularly irregular roadway it limits any damages which the structure of the tyre might incur, whilst in case of uniform and regular roadway, if the inflation pressure is lower than it should be, contact between said anti-flattening means and the tyre serves as a warning to restore regular pressure and use the tyres more properly.

In the case wherein said wheel is used under conditions of total lack of inflation pressure, the present invention is able to offer nearly optimal conditions of travel, inasmuch as the tyre is normally in contact with the central part of said anti-flattening means, thus the most elastic part, which by yielding in a variable manner in the same way as a regularly inflated tyre according to the size of the asperities of the roadway, gradually dampens any impacts or bumps received, whereas in the presence of considerable irregularities on the roadway the lateral areas realising a particularly effect support serve the purpose of limiting deflection to protect the flanks of the tyre. Moreover, in case of stresses of high intensity, said anti-flattening means are in contact with the circumferential band of the tyre over the entire width and in this way they distribute the localised stresses on a wider surface. Advantageously, the present anti-flattening means provide a particularly effective response to the functions they are called upon to perform, and particularly thanks to the comfortable travel they are able to offer even under conditions of flattened tyre on roadways in imperfect conditions and to the safeguard they offer to the flanks of the tyre in case of particularly insidious stresses.

Said invention globally provides a high and gradual elastic pliancy in the radial direction, inasmuch as the present anti-flattening means are activated as soon as the deflection of the tyre exceeds the deflection due to the elasticity of a regularly inflated tyre on a slightly irregular route, and allow a considerable excursion before behaving like a solid wheel.

This excursion, due to the elastic resources available to said anti- flattening means, in addition to using the space HI in full until said anti- flattening means come in contact with the circumferential surface 24, benefits from the capability of the second component 70, thicker in the central area and more yielding under compression, of flattening under the same stress.

The elastic resources available to said anti-flattening means manifest themselves progressively as a function of the stresses whereto they are subjected, and specifically the elastic pliability decreases progressively as deflection increases, obtaining a response of the wheel that is differentiated according to the intensity of the stress.

With the present anti-flattening means, if the stress is modest, the response of the tyre will take place in a softer manner with slower reaction times and a behaviour substantially comparable to that of a regularly inflated tyre, whereas for greater stresses it will gradually grow in intensity according to the stresses themselves.

Therefore, in case of a modest stress, for instance caused by a small asperity, only the more elastic and yielding part of the tyre intervenes, yielding in a manner that is recovered with a certain delay, generally after the asperity has been overtaken, without transmitting any stress to the vehicle, in a manner substantially similar to what occurs for a regularly inflated tyre.

By contrast, if the stress is greater, after the more yielding part has dampened part of the stress and has exhausted its elastic resources, the more rigid part comes into play which provides a more solid reaction, but since it intervenes only for the residual part of the stress, the reaction transmitted to the vehicle is rather small.

By suitably regulating the elasticity of these anti-flattening means, a gradual and progressive response is obtained, such as to have a uniform behaviour, with a level of impacts and vibrations that is definitely reduced with respect to the vehicles that employ anti-flattening means according to the prior art.

Figure 2 shows a second preferred embodiment 100 of the present invention. The parts which are similar or equivalent to parts of the first preferred embodiment are identified with the same numerical references and are not commented in detail again.

According to this embodiment 100 the first and the second part of the rim 22' and 22" are joined by a plurality of screws 136 distributed circumferentially and inserted transversely in appropriate through holes 138 on the part 22" in correspondence with the disk and corresponding threaded holes 137 on the part 22" in correspondence with an annular shoulder 135 extending radially inwards. Moreover, to offer the inflation chamber 14 a better seal guarantee, a sealing gasket 130 is provided, housed in an appropriate seat 132, which is located in correspondence with an indentation 134 on the part 22" able to house a transversely extended projection 133 presented by the part 22' with the function of coming in contact with said gasket.

Said rim 22 also presents in the extreme areas of said circumferential surface 24, in proximity with the projecting lateral edges 27, 28, portions of cylindrical surfaces 125, 126 with an increased diameter serving as seats for the keying and sealing of said tyre 40.

In a preferred manner, said anti-flattening means 50 comprise a first elastically yielding element 160 corresponding to said first component 60 of the first embodiment, preferably made of elastomeric material and with low elastic pliancy, constituted by a central portion 164, are in the form of a circumferential band yielding radially by flexion, at whose extremities, for its support, are positioned projections 161, 162 extending radially inwards and bearing on the circumferential surface 24 of the rim 22 in correspondence with the lateral areas 51, 52; moreover, in correspondence with said projections 161, 162 extending inwards, are present other radial projections 167, 168, extending outwards.

According to a further advantageous feature of the present invention, said anti-flattening means comprise a second elastically yielding element 170 corresponding to said component 70 of the first embodiment, also preferably made of elastomeric material but with greater elastic pliancy and positioned externally to said first element 160, which from the external side, which comes directly in contact with the circumferential band 46 of the tyre 40, though it presents a profile substantially corresponding with the illustration in Figure 1 , is traversed by several circumferential notches.

These notches go to generate a plurality of elastic radial projections 175, 173, 171, 172, 174, 176 extending radially, which present a tapered shape, having a cross section which starting form the outer face in contact with the circumferential band 46 increases radially inwards.

Said radial projections 175, 173, 171, 172, 174, 176, which could also be in a different number, to contact in a deferred manner the circumferential band 46 present different heights, and more specifically the radial projections 171, 172 positioned at the centre, present a greater height and come in contact with the tyre at a first time, subsequently the radial projections 173, 174 come into play, having intermediate height and being positioned to the sides of said radial projections 171, 172, lastly in the lateral areas are positioned the radial projections 175, 176, which present a lesser height and a greater width with respect to the others.

Taking into account that this second element 170 is sufficiently elastic by deformation, in case of flattening said radial projections 175, 173, 171, 172, 174, 176, able to be compressed radially, have the capability of expanding laterally allowing a high and gradually decreasing pliancy, which is due not only to the deferred manner of coming in contact with the circumferential band 46, but also to the fact that part of the radial projections are positioned in correspondence with the circumferential band 164, radially yielding by flexion, of said first element 160. In case of particularly intense stresses, the greater rigidity provided in the lateral areas by the projections 175, 176, due to their greater width and especially to the lesser thickness of said second, more elastic component 170 of said anti-flattening means, offers a more solid support to the tyre to safeguard its flanks more effectively. According to the present embodiment, a further third elastically yielding element 180 is provided, which could however also not be present, while the use of a greater quantity of elements could also be imagined.

Said third element 180 is interposed with a substantially constant thickness between said first element 160 and said second element 170, preferably made of elastomeric material, has an elastic pliancy that is lesser than said first element 160 and different, preferably lesser, than that of said second element 170, and contributes to make the present system even more elastic. Said anti-flattening means 50, though constituted by different element 160, 170, 180, are not necessarily constituted by different parts coupled by means of mitring, but could also be realised in a single body, in which case the various elements identify portions of material having different plastic characteristics. Figure 3 shows the embodiment 100 according to Figure 2 under conditions of use with the tyre regularly inflated and in the condition wherein the wheel has to support the weight that is normally applied. The contact of the tread 48 with the roadway 18 causes a deformation of the circumferential band 46 such as to reduce the distance between said circumferential band of the tyre 40 and said anti-flattening means 50 particularly in correspondence with said projections 171, 172 of said second element 170.

The subsequent Figure 4 shows the embodiment according to

Figure 2 under conditions of use with the tyre deflated, in which one can clearly observe the behaviour of said anti-flattening means 50 for supporting the tyre 40 in the condition wherein the wheel has to support the weight that is normally applied.

Under this condition, a reduction is noted of the space between the circumferential surface 24 of the rim 22 and the central area of said anti- flattening means 50 due to the radial yielding by flexion of said circumferential band 164 of the first element 160, and the deformation of the radial projections 173, 171, 172, 174 which are in contact with said circumferential band 46 of the tyre.

Said anti-flattening means 50 under this condition have further elastic resources available, particularly useful in case of travel over a roadway 18 in broken conditions, since a certain space still remains between the central area of said anti-flattening means and the circumferential surface 24 of the rim, the radial projections 173, 171, 172, 174 can compress further until the total saturation of the interposed spaces, while the lateral projections 175, 176 are not yet in contact with the circumferential band 46.

Figure 5 shows a third preferred embodiment 200 of the present invention. Parts which are similar or equivalent to parts of the previous figures are identified with the same numerical references and are not commented again in detail.

This third preferred embodiment differs 200 from the second embodiment 100 in that it has said anti-flattening means 50 composed by a first elastically yielding element 260 and a second elastically yielding element 270, which although they have substantially the same profile and the same behaviour of the corresponding elements 160, 170 according to the second embodiment 100, are nonetheless realised in a different manner.

In particular, said first element 260, corresponding to the components 60 and 160 of the previous embodiments, is in the form of a thin shaped metal lamina, preferably made of spring steel and possibly coated on the outer side of the profile with a layer of elastomeric material to avoid direct contact of the metal part with the circumferential surface 24 of the rim 22, so shaped as to present a circumferential central portion 264 for flexural support at whose sides it presents circumferential portions 267, 268 with a greater diameter, in such a way as to obtain a mitre joint for coupling with said second element 270.

The profile of said first element 260 extends radially inwards from the lateral extremities of said circumferential portions 267, 268 until coming in contact with the rim 22 where it presents circumferential portions 261, 262 bearing on the circumferential surface 24 in correspondence with the lateral areas 51, 52.

Said second element 270, corresponding to the components 70, 170 of the previous embodiments, differs in particular from the corresponding element 170 according to the embodiment 100 only in the lesser depth of the circumferential notches which are interposed to the radial projections

175, 173, 171, 172, 174, 176, and in the presence of additional circumferential notches 273, 271, 272, 274 in the inner part in correspondence with the radial projections; in this case the external radial projections have a lesser height with the advantage of diminishing the free lateral inflexion when loaded at their tip.

With reference to the subsequent Figure 6, it can be observed that said metal lamina defining the first element 260, of said anti-flattening means of the present second preferred embodiment 200, presents, starting from a central band or area 263 which extends over the entire circumferential length of said metal lamina, a first and a second series of transverse notches 265, 266 which extend transversely in opposite directions to said central band and are able to allow the circumferential folding back of the metal lamina itself.

Figure 7 shows a fourth preferred embodiment 300 of the present invention. Parts which are similar or equivalent to parts of the previous figures are identified by the same numerical references and are not commented again in detail.

This fourth preferred embodiment 300 presents the first elastic element wholly similar to that of the second embodiment 200 and differs therefrom mainly in that it employs a second elastically yielding element

370 corresponding to said second component of the previous embodiments which, instead of being in the form of a plurality of radial projections made of material that is elastically yielding by deformation as in the previous embodiment, is in the form of a single compressible elastic pad made of elastomeric material, with a different elastic module, which extends circumferentially, with an external profile corresponding to the definition of Figure 1 and extends transversely to the sides of the central portion, realising an arched profile 56, with lateral portions 375,

376, beyond the width of said first elastically yielding element 260 which supports it.

In correspondence with the projection of said portions 375, 376 with respect to said first element 260, respective circumferential portions

377, 378 extend radially inwards to improve coupling with said first element 260. Figure 8 shows a fifth preferred embodiment 400 of the present invention. Parts which are similar or equivalent to parts of the previous figures are identified by the same numerical references and are not commented again in detail.

This fifth preferred embodiment 400 provides a first element 260 of said anti-flattening means 50 corresponding to said first element of the previous embodiments which is substantially comparable to the corresponding element according to the embodiments 200 and 300.

In the upper part of the section view is positioned a second elastically yielding element 470 corresponding to the second component of the previous embodiments, preferably made of elastomeric material and with moderate elastic pliancy, which externally presents an arched profile 476 realised by a circumferential band 475 at whose sides internal projections 471, 472 and external projections 473, 474 extending radially inwards realise mitring means with said first element 260. In the inner part of said band 475 are positioned projections 477,

478, 479, extending radially inwards, for contact with the underlying third elastically yielding element 480 of said anti-flattening means 50.

Said third element 480, made of particularly elastic and compressible elastomeric material, positioned between said first element 260 and said second element 470, is in the form of a pad, which instead of having a circumferential shape could also have a linear development and then wrap internally around said second element 470, in the same way as said first element 260.

Figure 9 shows a sixth preferred embodiment 500 of the present invention. Parts which are similar or equivalent to parts of the previous figures are identified by the same numerical references and are not commented again in detail.

This sixth preferred embodiment 500 provides, in the section view, a first elastically yielding element 560 of said anti-flattening means 50, corresponding to said first component of the previous embodiments, preferably made of elastomeric material with a modest pliancy, having a central band 564 with circumferential development of arched shape, concave outwards, radially yielding by flexion, at whose extremities extend projections 561, 562 inwards until reaching the circumferential surface 24 and bearing thereon in correspondence with the lateral areas

51, 52.

Externally to said first element 560 is positioned a second elastically yielding element 570, corresponding to said second component of the previous embodiments, elastically yielding by compression, in such a way as to be interposed with the circumferential band 46, in the form of a pad bearing on said first element 560, with a substantially constant thickness.

Moreover, in the central area, internally to said first element 560, between it and the circumferential surface 24 a further elastically yielding element 590 extends, which could also be considered as a detached portion of said second element 570 in that it presents corresponding characteristics, in the form of a tapered projection prolonging from the interior of said arched band 564 in radial direction inwards.

Figure 10 shows a seventh embodiment 500B similar to the sixth embodiment according to Figure 9. This seventh embodiment shows, by way of example, some possible variations, which can be proposed individually also for the other embodiments already described.

Said rim 22 is divided in a different manner in that the radial portion or disk 21 forms a single element with the part 22' of said rim. The seat 132 for the gasket 130 and the related indentation 134 are obtained on the part 22' of said rim.

The portions serving as seats for the keying of the tyre instead of presenting cylindrical circumferential surfaces present portions of conical surfaces 125B, 126B to allow for better mounting. In the central area of the circumferential surface 24 a throat 523B is provided to allow a greater excursion of said anti-flattening means 50.

Said second elastic element 570B, instead of being in the form of a pad made of compressible elastomeric material, is made with a different elastomeric material which is non compressible, but yielding by deformation; the notches provided, which do not necessarily have the same size, serve to allow lateral expansion to permit such a compression as to offer a behaviour substantially corresponding to that of the elastically compressible pad.

This concept can also be applied to the additional element 590B, as it has corresponding characteristics.

Based on the embodiments provided purely by way of non limiting example and illustrated above, additional configurations are in any case imaginable.

The invention thus conceived can be subject to numerous modifications and variations, without thereby departing from the scope of the inventive concept. Moreover, all details can be replaced by technically equivalent elements.

Claims

1. Wheel for a vehicle, comprising a tyre (40) in the form of a container made of elastic polymeric material comprising an external circumferential band (46) realising a tread (48) in contact with the roadway (18), a rim (22) having a circumferential surface (24) for supporting said tyre defining therewith a chamber (14) for the inflation of the tyre itself, and anti-flattening means (50) with circumferential development in the form of elastically yielding means supported by said rim and positioned inside said inflation chamber, between the circumferential surface of the rim that supports said tyre and said external circumferential band realising the tread of the tyre, to sustain said circumferential band in a flattened condition of the tyre itself, characterised in that said anti-flattening means present a gradual and progressive elastic pliancy in the radial direction, being greater in the central area, where they also present a greater outer diameter, whereas in the lateral areas they present a lesser outer diameter and a lesser elastic pliancy.

2. Wheel according to claim 1, characterised in that said rim (22) comprises a first and a second part (22', 22") able to be associated by means of suitable connecting means (136).

3. Wheel according to claim 2, characterised in that said first part (22') of the rim (22) presents a circumferential projection (133) transversely extended which is housed in a corresponding indentation (134) provided on said second part (22") of the rim, in such a way as to realise a surface (24) for supporting said anti-flattening means (50) which is circumferentially uniform over the entire width of said inflation chamber (14).

4. Wheel according to claim 3, characterised in that in correspondence with the indentation (134) on said second part (22") of the rim (22) a seat (132) is provided for a sealing gasket (130).

5. Wheel according to any of the previous claims, characterised in that in correspondence with the central area of the circumferential surface (24), a throat (523) is provided to allow a greater excursion to said anti- flattening means (50).

6. Wheel according to any of the previous claims, characterised in that in the extreme areas of the circumferential surface (24) in proximity to the lateral edges (27, 28) and in correspondence with the keying areas of the tyre (40) portions of circumferential surfaces (125, 126) with an increased diameter are provided.

7. Wheel according to any of the previous claims, characterised in that in correspondence with the keying areas of the tyre (40) on the rim (22), portions of conical surfaces (125B, 126B) are provided.

8. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) are supported by the circumferential surface (24) of said rim (22).

9. Wheel according to claim 8, characterised in that said anti- flattening means (50) bear solidly on said circumferential surface (24) only in correspondence with the lateral areas (51, 52).

10. Wheel according to any of the previous claims, characterised in that in correspondence with the central area (54), in a condition of rest, a certain space (HI) always remains between the circumferential surface (24) and said anti-flattening means (50).

11. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) extend over the entire width between the edges or beads (41, 42) for keying the tyre (40).

12. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) are such that, in a condition wherein the tyre is deflated, they solidly maintain, when compressed, the edges of beads (41, 42) for keying the tyre (40) in contact with the respective lateral edges (27, 28) of the rim (22).

13. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) present a greater height (H3) in the central area (54) than in the lateral areas (51, 52).

14. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50), in a condition wherein the tyre is regularly inflated, in the central area extend in proximity to the circumferential band (46) of the tyre (40).

15. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) present a greater thickness (H2) in the central area (54) with respect to the thickness (H5, H6) of the respective lateral areas (51, 52).

16. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) comprise a first and a second component having different elastic characteristics.

17. Wheel according to claim 16, characterised in that said first component (60) sufficiently rigid and yielding by flexion in the central area (54) bears on the circumferential surface in correspondence with the lateral areas (51 , 52) where it presents a greater thickness.

18. Wheel according to either of the previous claims 16 and 17, characterised in that said second component presents a greater elastic pliancy than the first component and a greater thickness in correspondence with the central area (54).

19. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) present a greater elastic pliancy in correspondence with the central area (54) with respect to the lateral areas (51 , 52) where the more limited compression is allowed.

20. Wheel according to any of the previous claims, characterised in that said anti-flattening means (50) comprise a first elastic element (160) extending circumferentially and having a central band (164) able to yield by flexion in a radial direction.

21. Wheel according to claim 20, characterised in that said first element (160) presents in extension from the opposite transverse sides of said central band (164), a pair of projections (161, 162) extending radially inwards until reaching the circumferential surface (24).

22. Wheel according to claim 21 , characterised in that said first element (160) presents in correspondence with said projections (161, 162) further projections (167, 168) extending outwards.

23. Wheel according to any of the previous claims from 20 to 22, characterised in that said anti-flattening means (50) comprise a second elastic element (170), positioned radially outwards of said first element (160) and more elastic, in the form of a plurality of elastic radial projections (175, 173, 171, 172, 174, 176) extending circumferentially which present a cross section which, starting from the outer contact face, increases radially inwards.

24. Wheel according to claim 22, characterised in that said radial projections (175, 173, 171, 172, 174, 176) present different heights, greater at the centre and gradually smaller at the sides, such as to allow contacting said circumferential band (46) at deferred times.

25. Wheel according to claim 24, characterised in that said radial projections (175, 173, 171, 172, 174, 176) are able to be compressed radially and are transversely distanced from each other in such a way as to allow their free lateral expansion.

26. Wheel according to claim 25, characterised in that part of said radial projections (173, 171, 172, 174) are positioned in correspondence with said central band (164), yielding by flexion, of said first element

(160) and when compressed are able to provide a particularly high and gradually decreasing elastic pliancy.

27. Wheel according to claim 25, characterised in that the radial projections (175, 176) positioned at the sides, in correspondence with the underlying projections (167, 168), present a lesser height and a greater width than the others, such as to provide the tyre with a more solid support.

28. Wheel according to any of the previous claims from 16 to 27, characterised in that said anti-flattening means (50) comprise a third elastic element (180), radially yielding and positioned between said first element (160) and said second element (170).

29. Wheel according to any of the previous claims from 16 to 28, characterised in that said first elastic element (260) is in the form of a thin metal lamina, preferably made of spring steel, so shaped as to present a circumferential central portion (264) for flexural support.

30. Wheel according to any of the previous claims from 16 to 29, characterised in that said first element (260) presents, at the sides of said circumferential central portion (264), circumferential portions (267, 268) with a greater diameter in such a way as to realise a seat for said second elastic element (270).

31. Wheel according to claim 30, characterised in that the profile of said first element (260) extends radially from the extremities of said circumferential portions (267, 268) until reaching the circumferential surface (24), whereon in correspondence with the lateral areas (51, 52) it bears with circumferential portions (261 , 262).

32. Wheel according to claim 31, characterised in that starting from the central area (263) and extending over the entire development, said first element (260) presents a first and a second series of transverse notches (265, 266) which extend in opposite directions and allow its circumferential folding.

33. Wheel according to claim 30, characterised in that in correspondence with the lower surface of said second element (270), coinciding with part of said radial projections (173, 171, 172, 174), circumferential notches (273, 271, 272, 274) are provided.

34. Wheel according to any of the previous claims from 16 to 33, characterised in that said second elastic element (370) is in the form of a pad, made of elastomeric material elastically yielding by compression extending circumferentially with an external surface having an arched profile (59) in the central area.

35. Wheel according to claim 34, characterised in that said second element (370) presents at the sides of said arched profile (59) lateral portions (375, 376) beyond the width of said first element (260) and in correspondence with such projections are positioned radial portions (377, 378) extending inwards.

36. Wheel according to any of the previous claims from 16 to 35, characterised in that said second elastic element (470) is in the form of a circumferential band (475) with an arched profile at whose sides projections (473, 472, 472, 474) for coupling with said element (260) extend inwards.

37. Wheel according to claim 34, characterised in that from said circumferential band (475) projections (477, 478, 479) for contact with said third elastic element (480) extend radially inwards.

38. Wheel according to claim 37, characterised in that said third elastic element (480), in the form of a compressible pad is positioned between said first element (260) and said second element (470).

39. Wheel according to any of the previous claims from 16 to 38, characterised in that said first elastic element (560) presents a central band (564) with arched shape radially yielding by flexion at whose extremities are positioned projections (561, 562) extending radially inwards until reaching the circumferential surface (24) of the rim.

40. Wheel according to claim 39, characterised in that said second elastic element (570) is in the form of a pad realised by a circumferential band of substantially constant thickness laid on said first element (560) and made of elastically yielding and compressible material.

41. Wheel according to any of the previous claims from 16 to 40, characterised in that said anti-flattening means (50) present an elastically yielding element (590) in the form of a projection extending inwards from said circumferential band (564) made of material corresponding to said second element (570).

42. Wheel according to claim 41 characterised in that said second element (570B) is made of elastic material and is provided with circumferential notches (570B') to allow a greater elasticity by compression.

43. Wheel according to claim 42 characterised in that said element (590B) parallel to said second element (570B) is made of elastic material and is provided with circumferential notches (590B').