CA1094436A - Tyre and wheel rim assemblies - Google Patents

Abstract

ABSTRACT

A tyre and wheel rim assembly wherein the wheel rim includes adjacent to at least one bead seat a circumferentially extending groove and the tyre bead has a radially and axially ally projecting extended toe portion which is axially and radially located within said groove. The toe is flexible in a direc-tion substantially perpendicular to its length and substan-tially rigid in the direction of its length and provides an effective bead lock to retain the tyre bead in position on the rim.

Description

q~ ~4~;

This invention relates to tyre and wheel rim assemblies and in particular to tubeless tyre and wheel rim assemblies.
In conventional tyre an,d wheel rim assemblies the tyre beads are retained on the!ir respective bead seats by means of the internal air pressure and frictional restraint due to the compression in the elastomer under the bead wire when fitted onto the tapered seat of the rim. Lowering the air pressure in the tyre, however, lessene the retention force from internal air pressure and eventually at a qufficiently low internal pressure the asqembly reaches an unsafe condition in which the tyre beads may be displaced from their seats by sideways force such 'as i9 generated in an accident avoidance manoeuvre.

The European motor industry uses a variety of test3 to check bead dislodgement. A typical test is caxried out b,y testing a tyre and wheel rim as~embl,y as the outer front wheel i.e~ a left-hand or near side in a right-hand J turn test at 25 mph. The test comprisee straight running at 25 mph and then the sudden application of full steering lock. The test is repeated at progressiv01y reducing tyre in~lation pressure~ until dislodgement occur~. Usually the pre~sure reduction steps are 2 p9i. Typical production radial ply car tyres normall~ dislodge a bead at air pressures of ~he order of 5-15 psi in such A test.
Typical tubeless radial ply car tyres normally dislodge a bead at pressures of the order of 5-15 psi in such a test.
~i~

~09~436 Dislodgement of a tyre bead from its seat affects vehicle control. In the use of wheels which include a well to allow tyre fitting there is generally a grave danger of complete separation of the tyre from its wheel rim.
In the use of a vehicle, cornering generates sideways forces which displace the tread laterally with respect to the wheel rim. These forces are transmitted by the tyre carcass to the tyre bead. In the region of the tyre adjacent to the ground contact area axial forces ~i.e. in the direction of the tyre axis) and turning moments (i.e. about a circumferential line through the bead) are generated. In the absance of air pressure these forces may be sufficient to produce lifting of the heel of the bead thus reducing the frictional force between the bead base and the bead seat on the rim which, in said deflated state, is the only force which retains the bead on its seat~ As a result the bead moves down its tapered bead seat laterally inwardly of the rim flange reducing the tension in the bead wire and, very rapidly the residual bead retaining force b~comes less than the dislodging forces and the bead leaves its seat and falls into the well.
Previou~ attempts to solve thiC problem have centrad around the use of wheel rim~ which do not have a well. The resultant flat-based rim obviat6s the danger of tyre wheel ~eparation but has the disadvantage that the ~yre beads are u~ually able to move axially between the spaced-apart flanges.
Thus the ~ideways force which can b~ transmitted between the wheel and the ground changes suddenly from zero when a bead is moving across the rim to a maximum when both beads are -- 2 ~

1~4~36 together against a flange. Ihi8 may, ln the extreme, cause 1098 of control of the vehicle,.
This is equally true for a well based rim having a filling device, a wheel rim which has a fitting well closed by crimping after tyre fitting or a divided wheel rim a~embly.
A divided wheel rim system requires ~everal extra components with conqequent disadvantage~ in sealing the air chamber of the tyre, increased co~t, increased weight ~nd increased complexity for servicing. The well ~illing system also increases the a~sembly weight, cost and complicates servicing even though a one-piece wheel rim may then be utilised. None of the~e previous attempts, however, overcome the problems of ~ide force tran~mis~ion when a bead moves axially acros 9 the rim r Bead spacer rings which are rigid circumferentially extending ring~ filling the space between ~he two beads have been proposed for use with divided wheel rim~ to hold both beads in place, see for example, U.K. Patent No. 222,768.
Such devices provide the required properties but add yet another component to the already complex divided wheel rim as~embly.
Another modification to a divided wheel rim having a fl~t base and no w211 iS disclosed in U.K. Patent No.
1,395,714 in which a notch is formed between two wheel rim ~5 components at the outboard bead side of the flat base rim and an extended rubber toe i~ provided on the bead which rest~ freely in the notch. This assembly is still subject to all the complications of divided wheel rims including the 109443~;

air sealing problem and u~es a flat ba~ed wheel rim for safety in high side force con~itions.
~et another system is shown in U.K. Patent No.
890,959 where a divided wheel rim is proposed in which a fabric reinforced, rubber covered extension of the bead is clamped between the rim parts to seal the assembly. Whilst this may xetain the bead, effective sealing depends on accurate assembly and clamping of the bead extension.
The system is also still subject to the general dis-advantages of divided wheel rims.
One piece flat based wheel rims are known and one such assembly is di~closed in U.K. Patent No. 1,348,891 where a one-piece wheel rim has provided a well for tyre fitting which is subsequently closed by permanently crimping it closed so as to provide a flat based rim. Such an a~sembly has the further disadv~ntage of it being nece~sary to destroy the rim to repair the tyre or check the inRide for damage.
Still another system i9 to provida a well in the normal bead seat area at one ~ide of a ~lat based wheel rim and having fitted the tyre over the flanges using thi~ well to press both bead~ against the ~lange furthe~t from the well and insert a well filler which ~ubsequently forms the bead seat. Such a system i5 disclosed in U.S. Pa~ent No.
3,884,286.
Attempts to overcome the problem~ of bead retentisn and yet allow the use of a normal well in a wheel rim have included small circumferentially extending humps formed in the rim adjacent to the bead. Such humps can be 1.7 mm in 10~'1436 height relative to the bead seat toe diameter but, in any case, these must be lilnited to dimensions which permit a tyre to be fitted to its seats by inflation pressure without damage. The sideways forces generated by the road when the tyre is deflated greatly exceed the force generated by the inflation pressure and thus any hump which allows tyre fitting cannot prevent bead dislodgement and thus the tyre bead is able to enter the well.
One-piece wheel rims having radially movable stops adjacent to the bead seat are also known but here again to provide the necessary stop movement adds complication, cost and air sealing problems to the assembly.
More recently in U.S. Patent ~o. 3,951,192 it has been proposed to provide hook-like extensions formed on the outer lower sidewall areas of the tyre and shaped to engage around the wheel rim flange so as to resist bead movement.
However, sideways orce~ rotate the bead with resulting heel lifting and thus this con~truction cannot, in our experience, be satisfactory. In addition they are ~ubject to the like-lihood of damage from kerbstones.
Thus all known previou attempts to provide for positive bead retention and thus the ability to control a vehicle even when a tyre is deflated have either not provided a solution or have been complex and therefore too costly.
The automobile industry currently its tyres to rims automatically using firstly a machine which rolls bo~h ~eads over one flange using the well to give the neces3ary clearance and secondly a so-called 'explosion' inflation device which 10~4436 almost instantaneously inflates the tyre and forces the beads onto their respective bead seat~. This means that the industry requires tyre and wheel rims compatible with this machinery.
We have investigated the phenomena of the forces involved in dislodging the beads of a tyre from a wheel rim when on a vehicle. We have also investigated the phenomena of the forces involved in fitting tyres to and removing tyres from wheel rims. We have found that the road generated forces involved in tyre bead dislodgement are quite different from the forces involved in the removal of a tyre from the wheel rim with the wheel tyre aæsembly removed from the vehicle or tyre replacement or repair.
Accordingly we have utilised the difference between the road generated dislodgement forces and the tyre removal forcec to provide a bead lock which obviates the above problems and allows for the safe use of a one-piece wheel rim.

~0 ~0~4436 According to one aspect of the present invention is pro~7ided a tyre and wheel rim assembly wherein the tyre comprises a tread portion, sidewalls and a pair of beads each containing a substantially inextensible annular reinforcement and heing seated upon a bead seat one a~
each side of the wheel rim, the wheel rim including a tyre fitting well and being formed axially inward of and adjacent to at least one bead seat to provide a circumferentially extending groove which axially and radially locates at least the radially inward extremity or tip of an extended toe portion of the associated tyre bead, the said toe portion comprising elastomeric material, extending length-wise from the annular reinforcement to the tip in a direction radially and axially inwards of the annular reinforcement, being flexible in a direction perpendicular to its length to allow tyre fitting and being substantially rigid in the direction of its length such that when an axially inward force at the tread portion is applied to the bead by the tyre sidewall in the ground contacting portion of the tyre circumference, a substantial radially and axially outwardly directed force is generated at the annular reinforcement the generated force tightening the annular reinforcement and retaining the bead.
Preferably the toe rigidity is enhancPd by means of a reinforcement layer adjacent to the outer surface of the toe.
The reinforcement layer may extend part of the way around the toe or all of the way around the toe and may comprise one or more plies of material. Preferably the reinforcement ply -~ lOg4436 comprises a fabric which may k,e cross-woven or ~nitted.
The elastomeric material of the toe preferably has a hardness measured under laboratory conditions greater than 50 ShoreO More preferably the hardness is in the range 60-96 Shore.
It is preferred that the radially inward edge of the bead seat of the wheel rim is smoothly radiused into the circum-ferential groove and the grooves may have a symmetrical cross-section about a radial line taken through the point o~ maximum groove depth.
So that the toe will enter into engagement with the groove when the tyre is fitted to the wheel rim the axial length of the bead seat and toe of the tyre~ when the tyre is straightened is preferably less than the distance from the heel point onthe rim measured along the bead seat to the nearest point on the axially inboard face of the groove.
Whilst a groove and toe may be provided at either side of the wheel rim and tyre preferably a groove and toe is provided at both sides.
According to another aspect of the present invention a tyre for a tyre and wheel rim assembly comprises a tread portion, sidewalls, and a pair of beads each containing a substantially inextensible annular reinforcement and an extended toe portion comprising elastomeric material and projecting axially and radially inwards of said tyre bead seat toe portion being adapted to be flexible in a direction substantially perpend-icular to its length and to be substantially rigid in the direction of its length.
~ccording to another aspect of the present invention a wheel rim for a tyre and wheel rim assembly as described comprises a pair of spaced-apart flanges~ bead seats, a well and adjacent at least one bead seat a circumferentially extending groove.
_ g _ 10~44~36 Several embodiments of the present invention will now be described, by way of example only, to show the scope of application of the present invention. The embodiments will each be described in conjunction with diagrammatic drawings which relate to each embodiment as follows:-The first embodiment is a 180 65 SR 340 radial tyreand wheel rim assembly. A cross~sectional profile of the assembly is shown in Figure 1, a detalled half-section of the tyre is shown in Figure 2 and the rim is shown in detailed cross-section in Figure 5.
The second embodiment is a 180 65 SR 340 'Denovo' (Registered Trade Mark) run-flat type of tyre/wheel rim assembly and a cross-sectional profile of the aqsembly is ~ shown in Figure ~ a detailed half-section of the tyre is shown in Figure 4 and the wheel rim is shown in detailed cross-section in Figure 5.
Figures 6, 7, 8, 9, and lO are shown to assist in the following description of the operation of the invention based on the current understanding of said invention and show respectively a cross-section of a tyre and wheel rim assembly in the ground-contacting area running deflated, an enlarged detail o~ the bead and wheel rim bead seat area in the condition of Figure 6, a similar enlarged detail of the bead and wheel ~m bead seat area with a side face applied to the tyre tread, the tyre bead fitting operation and the tyre bead removal operatiOn.
A third embodiment which is a 150/65 SR 320 radial ply tyre and wheel rim assembly is shown in cross-sectional 10~ L~ 4 36 profile in Figure 11, a detail.ed half-section of the tyre is shown in Figure ~ and the wheel rim dimensions are to be described in relation to the wheel rim in cross-sectional profile of Figure 13.
A fourth embodiment is a 150/65 SR 320 'Denovo' (Registered Trade Mark) run-fl.at type tyre and wheel rim assembly. Figure 14 is a detailed half~section of the tyre and the wheel rim profile is again to be described with reference to Figure 13.
A fifth embodiment is a 240/65 395 radial ply tyre wheel rim assembly the cross-sectional profile of which is shown in Figure 15, a detailed half-cross-section of the tyre is shown in Figure 16 and the wheel rim is to be described with reference to Figure 13.
A sixth embodiment is a 240/65 395 'Denovo' (Registered Trade Mark) run-flat type tyre and wheel rim assembly shown in cross-sectional profile in Figure 17.
A de~ailed half-section of the tyre is shown in Figure 18 and again the wheel rim is to be described wi~h reference to Figure 13.
A seventh embodiment, a 200/50-395 radial ply tyre and wheel rim assembly, is shown in cross-sectional profile in Figure 19, a detailed cross-section of the tyre is shown in Figure 20 and the wheel rim is to be described with reference to Figure 13.
An eighth embodiment is a 560 x 13 tubeless cross-ply tyre/wheel rim assembly shown in cross-section in Figure 21. The wheel rim of this embodiment is to be ~094436 described with reference to Figure 13.
Figure 22 shows in cross-section an alternative known wheel rim having a substantially straight portion outwardly of the normal flange face.
The sixth embodiment is a radial ply tyre mounted upon the wheel rim of Figure 22 and Figure 23 shows the assembly in cross-section.
Figure 24 is a cross-section of a tenth embodiment which is a run-flat 'Denovo' (Registered Trade Mark) tyre mounted upon the wheel rim of Figure 22.
Figure 25 is a cross-sec~ion of a final described embodiment which is an alternative radial ply tyre known in the art to that of Figure 23 having a con~truction particularly adapted to suit the wheel rim of Figure 22.

109~436 The embodiment of Figure 1 is a 180 65 SR 340 radial ply tyre with a steel breaker and fitted to a llo mm wide wheel rim having a diameter of 342 mm.
As shown in Figure 2 the tyre has a single radial carcass ply 1 of rayon and a ~reaker comprising two cut steel plies 2,3 which are at 18 to either side of the mid-circumferential plane of the tyre. The first ply 2 has an axial width of 126 mm. Each tyre bead wire 4 comprises a 6 x 6 (strands x turns) of 0.038" diameter steel rubber coated. An apex strip 5 is positioned above each bead and has a length of 30 mm and is made ~rom rubber of 80 Shore hardness. A filler 6 of rubb~r coated nylon tyre fabric is poæitioned around the bead wire with the nylon cords at 45 to the radial direction. A clinch strip 7 of rubber material is positioned in the outer part of the bead and extends to a radial height of 42 mm. An additional strip 8 of hard rubber material is positioned radially and axially inwards of the bead wire to form a toe 10. A toe reinforcement strip 9 of cross-woven nylon fabric is pQsitioned with the cords of the fabric at 45 to the radial direction so as to extend from the clinch ~trip 7 around the outer surface of the bead and the toe 10 as shown in Figure 2.
The tyre i~ cured using a clip ring shaped to the required toe shape shown in Figure 2 and the completed tyre has an extended toe of hard rubber incorporating a rein-forcement strip 9. The toe has an axial length A* of 20 mm, an end width B* of 5 mm and a radial length C* of 6 mm.
The hard rubber material of the toe strip 8 has a ~og~436 nominal hardness of 80 Shore.
The tyre assembly shown in Figure 3 is a 180 65 SR 340 'Denovo' (Registered Trade Mark) tyre mounted on a 110 mm wide wheel rim. Such a tyre/wheel rim assembly is designed to be able to run deflated for substantial distances.
The tyre is shown in more detail in Figure 4 and comprises a single radial carcass ply 11 of rayon and a breaker of two cut-steel plies 12,13 one at 18 to either side of the mid-circumferential plane of the tyre. The inner steel breaker ply has a width of 126 mm. A high resilience rubber composition 14 is used in the shoulder and upper side wall portions of the tyre as described in ~n.
Patent ~o. 964,9~1.
The tyre has a lubricant/sealant material coated on the inner surface of the tyre in the region of the tyre crown which provides a sealant to re3eal a puncture and a lubricant to avoid internal damage and reduce heat build-up when running flat. Further details of ~uch a coating are given in Can. Patent Application No.-271,398 filed Feb. 2, 1977.
The tyre lower sidewall and bead is constructed the same as that for Example 1 and in both cases the tyres are fitted to a 110 mm wide wheel rim as shown in Figure 5.
The wheel rim i~ rolled from .092" thick steel and the dimensions are as follow~:-- 25 ~ 110 mm ~ 21 mm Q 41 mm V 29.5 mm 10~436 p 20 mm U 37 mm B 12 mm H 13 mm T 5 mm Dl 340 mm G 12 mm D 342 mm Rg 7 mm rad R4 6 mm rad R5 4 mm rad R85 mm rad max R7 3 mm rad T 5 mm w 5 + 1 11 9 mm rad Tha above described tyre/wheel assemblies are suitable for a vehicle ha~ing an axle load of 1840 lbs.
Figures 6-10 relate to the operation of the bead lock and will be described later.
The tyre/wheel rim as~embly of Figure 11 is a smaller tyre/wheel assembly being a 150/65 SR 320 radial ply tyre fitted to a 95 mm wide rim.
The rim dimensions are as followso-A 95 mm B 12 mm Dl 318 mm D2 320 mm ~.0'~^~436 G 12 mm P 18 mm H 13 mm L 20 mm Q 37.5 mm T 5 mm U 27 mm V 27 mm R4 6 mm R5 4 mm 7 3 mm 8 5 mm Rg 7 mm W 5 + 1 The material thickness is .092".
The radial ply tyre shown in Figure 12 comprises a single radial carcass ply 1 of rayon and a breaker comprising two cut-steel plies 2,3 which are at 18 to either side of the mid-circumferential plane of the tyre. The first ply 2 has an axial width of 96 mm.
The bead wire 4 comprises a 5 x 4 (strands x turns) of .038 diameter steel wire rubber coated. An apex strip 5 made from hard rubber compound as above is positioned above the bead and has a length of 25 mm. A filler ply 6 of rubber coated weftless nylon fanric is positioned over the bead wires with the nylon cords at 45 to the radial direction and a clinch strip 7 of hard rubber is positioned outwardly overlapping the apex strip 5 and extends to a radial height of 36 mm.

.: .

1~0'~4~36 An additional strip of 80 Shore hardness rubber compound is used to form the toe lO and a toe reinforcement strip of cross-woven nylon fabric to the same specification as the first example is positioned to form the outer toe surface. The toe construction is the same as in the first example except that the axial toe length A* in this case is 18 mm whereas in the first example A* was 20 mm.
The tyre shown in Figure 14 is a run-flat 'Denovo' (Registered Trade Mark) type cf tyre of the same overall 150 65 SR 320 dimensions as the tyre in Figure 2. It is fitted to the same rim as the tyre of Figure 12. The tyre differs from the radial tyre in that the sidewalls are thickened and include a high resilience rubber compound 14 in the shoulder.
A lubricant sealant layer is utilised for run-flat performance.
Both these features are the same as for the second embodiment.
The tyres of Figures 10-14 are suitable for small cars having an axle load of 1280 lbs.
The tyre/wheel assembly of Figure 15 is a 240/65 - 395 radial ply tyre fitted to a 395 mm diameter rim. The tyre constructional details are ~hown in Figure 16 and the rim dimensions, using the same nomenclature as Figure 13 are as follows:-A 170 mm B 12 mm Dl 393 mm D2 395 mm G 13 mm ~OS3^~436 P 20 mm H 14 mm L 21 mm Q 47 mm T 7 mm U 50 mm V 33.5 mm R4 8 mm 5 mm R7 5 mm R8 8 mm W 5 + 1 The material thickness is .144".
The tyre comprises a two ply radial casing 50 of rayon and two folded edge steel breaker plies 51. The tyre beads 54 each comprise a 6 x 6 (strands x turns) winding of steel wires having a diameter of .038" coated with rubber. An apex strip 55 of 80 Shore hardness rubber is provided having a length of 42 mm. A filler ply 56 of rubber coated nylon fabric is positioned around the bead wire and extends to a radial height of 42 mm on the inside o~ the bead and 28 mm on the outside of the bead. The two carcass plies 50 are arranged around the bead assembly in the usual manner and a ; climch strip 57 of 80 Shore hardness rubber compound is positioned outwardly of and overlapping the apex strip 55 so as to extend to a radial height of 48 mm.
The toe 60 is formed from a strip 58 of 80, Shore hardness rubber compound and a toe reinforcement strip 59 of , . . .

cross-woven nylon material as used in the first example is positioned around the outer surface of the toe and bead as shown. The finished tyre has the shape shown in Figure 16 and the axial toe length A* ir this case is 20 mm as in the first embodiment.
The tyre and wheel assembly of Figure 17 is a 240/65 -3g5 'Denovo' (Registered Trade Mark) type tyre fitted to a 395 mm diameter wheel rim. The tyre construction is shown in Figure 1~ and its overall dim~lnsions are the same as the tyre of Figure 16. The wheel rim is also ~he same as that described for the embodiment of Figures 15 and 16. The tyre structuxe is basically the same as that of the tyre of Figure 16 except that the sidewalls are thickened by a layer 61 of high resilience rubber. The details of the reinforcement ma~erial are the same as for the first example but in this case the material is 15 mm thick rom the carcass ply in the tyre shoulder, 10 mm thick in the mid-sidewall region and tap~rs to the carcass under the breaker and at the apex strip as shown. The outer sidewall and clinch strip 57 are also thiclcer than in the radial tyre of Figure 16 the sidewall rubber being 8 mm thick in the mid-sidewall region.
The tyre/wheel assemblies of Figures 15-18 are suitable for a vehicle havin~ an axle load of 3200 lbs.
The above described examples are all 65 series tyres i e. each have an aspect ratio of 65%. The invention has also been applied to other aspect ratio radial tyres and the embodiments of ~igures 19 and 20 is a 50 series radial ply tyre having dimensions of 200/50 - 395 and which is fitted ~.0~ 6 to a 395 mm diameter wheel rim having the same dimensions as the embodiments of Figures 15-18.
The tyre has a two-ply rayon carcass 61 and two folded ply steel breakers 62 having a width of 150 mm. The bead area is the same as that of Figures 15-18 in relation to construction, dimensions and materials.
The invention has also been applied to a cross-ply tyre one example of which, shown in Figure 21, is a 560/13 tubeless tyre which is mounted on the same tyre rim section as 'che third embodiment i.e. a 110 mm wide wheel rim but with a diameter of 13". The tyre carcass comprises two plies 63, 64 of rayon.
The beads in cross-section are dimensionally the same as the first embodim~nt and comprise 6 x 6 (strands x turns) of .03~" diameter rubber coated steel wire. An apex strip of 80 Shore hardness rubber material extends to a length of 30 mm and a clinch strip ~ of 80 Shore hardness rubber compound extending to a radial height of 42 mm iq positioned in the outer regions of the bead. The bead toe ~S includes a reinforcement strip of cross-woven material exactly ~he same as the first embodiment.
Another known car tyre assembly uses a different rim profile to the abov~ standard radial, cross-ply and 'Denovo' run-flat types of tyres. The rim is shown in Figure 22 and comprises at each edge a portion 71 which is substantially straight when viewed in cro~5-section as shown, and which provides a flat surface which may contact a tyre fitted to th0 rim. The rim having this feature is modified according - 19 ~

~09443~i to the present invention and thus the remainder of the rim comprises at each side flange 72 connecting the straight portion 71 to a bead seat region 73~ Immediately inboard of the bead seat region 73 is formed a groove 74 which extends circumferentially around the rim, one groove 74 being provided at either side of the rim. Between the two gxooves 74 is provided a well 75 for tyre fitting in the usual manner. Typical rim dimensions are as follows:-A 125 mm B 17.6 mm U 42 mm L 29 mm 0 40 mm V 29.8 mm P 20 mm G 13.5 mm D 395 mm Dl 393 mm T 5 mm H 13 mm X 5.7 mm W 5 ~ 1 R5 4 mm rad R4 6 mm rad R8 5 mm rad R7 3 mm rad R11 4 mm rad ~09'~6 Rl2 7 mm rad The tyre and wheel rim assembly shown in Figure 23 comprises a radial ply tyre having a steel breaker 76 and a textile carcass reinforcement 77 fitted to the rim of Figure 22. The tyre is of the ~ame construction as the first embodiment. The textile carcass reinforcement 77 follows the standard shape from the mid-sidewall region to the bead region i.e. the initial portion A of the textile carcass reinforcement 77 is convex and the second portion B
of the textile carcass reinforcement is concave (both when considered from the outside of the tyre). The tyre has an outer bead profile to correspond with the wheel rim and in particular to the straight portions 71 so that the tyre then matche~ the wheel rim as shown. Each tyre bead includes a bead wire 78 and an extended toe 79 which is formed from hard rubber material (for example 70-90 Shore).
The toe shape i~ such that the assembled tyre and wheel is as shown in Figure 23 and the toe i9 the same ac that de~cribed for the fir~t embodiment.
The tyre and wheel rim ~sembly 3hown in Figure 24 i9 a run-flat ver~ion of the tyre ~hown in Figure 23 and compri~es a ~ingle xadial carca~s ply 80 of rayon and a breaker 81 of two cut-steel plies. The tyre i9 of the same con~txuction a~ the second embodiment and the tyre beads are con~tructed a~ described to provide the required toe 79 to engage the groove6 74 in the rim. Once again the outer profile of the tyre in the region of the bead and ~0~36 lower sidewall is moulded so that the tyre again matches the wheel rim as shown in Figure 24 as described in the previous embodiment.
The assembly shown in Figure 25 comprises a tyre which has a ratio of height to width less than 1.0, in this case 0065 and a carcass reinforcement having a neutral fibre that follows, at least between the mid~height of each of the sidewalls and their respective bead wire, the natural equilibrium curve of a single ply carcass having no breaker when such a carcass is subjected to inflation pressure. The curv~ is tangential to the bead rings, passes through the edges of the breaker and passeæ through the points in the sidewalls at which tangents drawn to the reinforcement are perpendicular to the tyre axis.
The tyre comprises a carcass reinforcement ply 82 which is folded around each tyre bead wire 83,84 and a breaker structure 85 to rein~orce the tread region. The carcass ply 82 in the lower sidewall zone is shaped to d~
U 3 remain ~ ~Y~ when viewed from out~ide the tyre until it 0 becomes a tangent to the bead wire 83. Thus the reinforce-C~V~*~
ment ply is ~e~e~ throughout the zone indicated C. Above the lower ~idewall zone C the carcass ply 8~ follows the neutxal equilibrium curve referred to until in the ~houlder zone 86 it is blended to curve smoothly to become a tangent 5 to the breaker structure 85 as shown.
The tyre carcass ply 82 in the lower sidewall zone C is particularly shaped so as to be substantially parallel to the straight portion of the wheel rim ~ . ~urther .

10~4~6 details of the tyre carcass are published in U.S. Patent Specification No. 3,910,336.
According to the present invention, howevçr, the lower bead region 87 is shaped the same as in the first embodiment so as to provide a toe 79 which engages the circumferentially extending groove 74 in the wheel rim to provide a bead lock according to the present invention.
As published in U.S. Patent No. 3,910,336 are property of this type of tyre is that the ~yre character-10 istics may be modified by changing the rim width for agiven tyre width. This may be done as long as the flange, bead seat and circumferential groove shapes are maintained as shown without impairing the bead locking.

105~436 The operation of the invention will now be described with reference to the first ~mbodiment. The discu~sion is for the tyre section in the ground contact area. The bead toe 10 is longer in the radial direction than the groove depth t6 and 5 mm respectively, see Figures 2 and 5) and thus when assembled by the method which will be described later the toe 10 is under a degree of precompression between the groove 15 in the wheel rim and the bead wire 4. The tyre is retained on the wheel rim by the normal bead wire tension o force applied to the bead seat and the tyre/wheel rim assembly may be run inflated as normal.
Figure 6 shows the tyre and wheel assembly of Figure 1 in the tyre/ground contact area deflated but with no side force applied. In a cornering or turning manoeuvr0 a side force SF is developed increasing in intensity as the lateral acceleration increases. This side force distorts the tyre sidewa~s relative to the rim and causes the outboard bead to rotate. As a toe is provided according to the present invention, the centre of rotation of the bead is the end 10 of the bead toe which is located axially and radially in the groove 15 formed in the wheel rim and thus the moment i~
SF x Xl where Xl i~ the distance measured radially from the tread contact area to the centre of rotation.
The tyre bead is retained against thi~ rotation by the moment o the bead wire tension about the same centre of bead rotation = Tl x X2 where X2 = the axial distance of the bead wire from the centre of rotation. It should be noted that there is no retention force due to air pressure as the

- 2~ -~0~ 36 tyre is being considered in the deflated condition.
Figure 7 shows on an er,larged scale the forces applied to the outboard bead seat on the onset of bead rotation. In the condition shown the fitted bead tension rrl which pre-compresses the rubber in the area under the bead wire issufficient to retain the bead on its seat by frictional grip, any momenk due to the precompression force in the toe then being small.
Increased side force generates an increased moment lo SF x xl. This initiates the bead rotation and the bead wire 4 begins to move in the direction I inwardly of ~he wheel rim.

The bead wire 4 is a subs~antially inex~en~ible hoop around the wheel rim and thus cannot follow the required circular locus to . rotate about the centre of rotation. Thus the bead wire 4 rotates and moves axially inwards to the position shown in Figure 8. The complete toe of the tyre, which has an effective length Dl in Figure 7 is thereforP compre~ed to a ~maller effective length D2 in Figure 8 which shows the po~ition when the tyre is subjected t:o a degree of side force.
The toe is substantially rigid in the direction of its effective length being made from hard rubber and having a reinforcement ply and being dimen~ioned to have a substantial compression stiffness or form stiffness along its length.
The reaction forces have a resultant force F3 generated by the toe against the bead wire 4 which has an axially outward component F4 and a radially outward component F5. The force F5 greatly increases the tension in the bead wire 4. The latter tension adds to the tension force Tl an additional ~ 25 -~0~4~36 component T2. Thus the retair,ing moment Tl x X2 is increased to Tl X3 + T2 X3 and rotation of the bead section has occurred about the centre of rotation to provide a balanced force condition and no further bead movement.
The above force balance occurs in the ground contact area only where the high side force is in fact applied to the tyre by the ground. However, the increased bead wire tension affects the compl~te hoop of the bead wire 4 and tightens it onto the rim. This increases the grip of the tyre bead to the bead seat of the wheel rim. sead rotation in the ground contact area may be of the order of go when considered as the angle Of rotation of the normal boad seating portion 18-18 of the bead.
The bead toe between ~he bead wire 4 and the groove 15 may be given the required form stiffnesq by various means apart from the construction de~cribed. It may for example be made entirely from hard rubber composition or other elastomeric compositions and it has been shown that a toe of the same shape but made of rubber having a hardne~s of greater than 80 Shore gives a satisfactory bead lock. The composition may include known additive~ for providing the required properties for example fibrous reinforcements which may be linearly or randomly orientated.
The toe may have more than one reinforcement ply 9 and/or in addition the reinforcement ply may comprise separate sections of fabric. The fabric may be woven, non-woven or knitted and made from various reinforcement material~ known in the art. The fabric of the reinforcement ply 9 is selected for two purposes, fir~tly to prevent bulging ~0~ 36 of the toe and thus contributing to the form stiffness when the toe is under lengthwise compression, and secondly to assist fitting as will be described. It should be noted that the toe materials are not under any substantial load S except in the side force conditions which occur when steering of the vehicle is effected with the tyre deflated or substantially deflated.
The toe end 10 must be radially and axially inwards of the head coil 4, so that it comes under increasing compression when the bead is subjected to a rotational moment as described. The moment applied by the side force to the outboard bead may be increased in the ground contact area so as to generate the maximum incr~ased compression and the greatest bead wire tension. The moment may be increased by using a stiffer lower sidewall area for example by a larger bead apex 5 than in conventional tyres and such a stiffened apex is used in the examples. By lower sidewall is meant the sidewall between the bead wire and a horizontal line drawn through the widest portion of the tyre when inflated to normal inflation pressure and unloaded.
The shape of the end 10 of the toe is not critical although the flat-ended construction shown in the Figures showing tyres is conveniently manufactured ueing a modified clip ring and using the moulding diaphragm to form the inner curved toe surface. When assembled to the rim the centre of pressure between the toe end and the groove; moves around the base of the groove 15 so that the toe does not readily buckle when the bead is rotated by the side force. Thus the 10'~436 preferred groove shape has a radiused based as sh~own although other shapes may be utilised.
The wheel rim may be rolled by the conventional wheel manufacturing process.
The initial location or grip of the toe end 10 in the groove base 15 before rotation begins may be further improved by means of roughening the groove e.g. by knurling although with the above described embodiments this is not necessary.
Tyre fitting to the rim is conventional. The tyre may be fitted over the flanges by hand tools, normal service equipment, or automatic tyre fitting machinery. Upon inflation the bead slides onto its seat under the inflation pressure I.P.
as shown in Figure 9. The toe being made of elastomeric material is able to bend to the position shown and when the bead reaches its fully home po~ition on its bead seat 18-18 the tce is able to snap into the groove using the recovery properties of the rubber of the toe in combination with the reinforcement ply 9 . When fully inflated the toe positively engages in the groove as shown in Figures 1 and 3 so that the toe end 10 is radially and axially located in the groove base 15 and the toe is under a degree of precompression between the groove and the bead wire 4.
To ensure correct fitting the straightened toe length Hl mea ured from the heel point H.P.l to the toe end 10 must be less than the distance from the heel point H.P.2 of the xim along the bead seat 18-18 and to the nearest point on the inboard face 19 of the groove 15 i.e. the length of the line H2.

109~436 In the embodiments described to ensure tyre fitting the distance measured in the axial direction from the vertical part of the flange to the centre line of the groove must be at least the same as the axial distance from the end of the toe to the flange contacting vertical part of the bead before the tyre is fitted. These dimensions are both 20 mm in the examples.
Tyre bead removal is shown in Figure 10. Conventional tyre removal tools comprise a spade ended tool 20 which is engaged between the wheel rim flange 21 and is then forced towards the centre of the tyre wheel assembly in the axial direction. The force does not produce any substantial bead rotation and the tyre bead can be successfully dislodged with the toe flexing sideways and without any damage to the tyre bead or toe.
The tyre wheel assemblies described above in relation to Figures 1 -5 were tested as the outer front wheel in a J
turn test (i.e. straight running followed by a full steering lock application) with the valve core removed. The test was ~0 repeated at successively higher speeds on a high grip tarmac surface. Neither of the embodiments dislodged at 40 mph which represents an applied side acceleration of the order of 1 g.
~igher speeds do not apply greater side force to the tyre since under such condition~ the vehicle slide~. In Slalom testing at speeds in excess of 70 mph when the direction of the side force changed bead dislodgement did not occur. The assemblies were ~imilarly proved on all other wheel positions.
Accordingly the assemblies were absolutely safe from - 2~ -10~ 36 dislodgement at the maximum sideforce available even under extreme test conditions.
Even after the above tests the tyres were readily removed from the rims using a conventional hand-operated tyre demounting machine.
Filmed evidence of the tyre behaviour on the rim confirmed that the tyre bead moves in the ground contact area to lock the tyre to the wheel rim in the manner described.

~0~436 Different rim widths and tyre sizes have been tested successfully using bead locks to the present invention. In the case of different rim widths different material thicknesses may be required for wheel rim strength and to allow convenient rolling the groove dimensions are changed accordingly. The tyre toe dimensions are also changed in proportion and the invention operates precisely as in the detailed case described above~
The invention operates with different tyre section widths, aspect ratios and bead diameters and applies also to all other known tyre constructions tubed or tubeless including radial ply tyres, belted bias tyres, cross-ply tyres and run-flat 'Denovo' (Registered Trade Mark) type tyres.
The bead lock is preferably applied to both tyre beads although it may be applied to only the inboard or outboard bead.

Claims (99)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows :-

1. A tyre and wheel rim assembly wherein the tyre comprises a tread portion, sidewalls and a pair of beads each containing a substantially inextensible annular reinforcement and being seated upon a bead seat one at each side of the wheel rim; the wheel rim including a tyre fitting well and being formed,axially inward of and adjacent to at least one bead seat,to provide a circumferentially extending groove which axially and radially locates at least the radially inward extremity or tip of an extended toe portion of the associated tyre bead, the said toe portion comprising elastomeric material, extending length-wise from the annular reinforcement to the tip in a direction radially and axially inwards of the annular reinforcement, being flexible in a direction perpendicular to its length to allow tyre fitting and being substantially rigid in the direction of its length such that when an axially inward force at the tread portion is applied to the bead by the tyre sidewall, in the ground contacting portion of the tyre circumference, a substantial radially and axially outwardly directed force is generated at the annular reinforcement the generated force tightening the annular reinforcement and retaining the bead.

2. A tyre and wheel rim assembly according to claim 1 wherein the toe rigidity is enhanced by means of a reinforcement layer adjacent to the outer surface of said toe.

3. A tyre and wheel rim assembly according to claim 2 wherein the reinforcement layer extends from the tip of the toe around the axially inwards surface of the toe to at least the radial height of the centre of the annular reinforcement.

4. A tyre and wheel rim assembly according to claim 2 wherein the reinforcement layer extends from the bead seat region of the bead around the toe and upwards along the axially inner surface of the toe to at least the radial height of the centre of the annular reinforcement.

5. A tyre and wheel rim assembly according to claim 2, wherein the reinforcement layer comprises at least one ply of material.

6. A tyre and wheel rim assembly according to claim 5 wherein the reinforcement ply comprises a fabric.

7. A tyre and wheel rim assembly according to claim 6 wherein the fabric is a cross-woven fabric.

8. A tyre and wheel rim assembly according to claim 7 wherein the fabric is of nylon.

9. A tyre and wheel rim assembly according to claim 6 wherein the fabric is a knitted fabric.

10. A tyre and wheel rim assembly according to C 1 a i m 1, wherein the elastomeric material of the toe has a hardness when measured under laboratory conditions greater than 50° Shore.

11. A tyre and wheel rim assembly according to claim 10 wherein the hardness is in the range of 60 - 96° Shore.

12. A tyre and wheel rim assembly according to C 1 a i m 1, wherein the radially inward edge of the bead seat of the wheel rim is smoothly radiused into the circumferential groove and the toe is profiled to a complementary shape.

13. A tyre and wheel rim assembly according to Claim 1, wherein the groove has a symmetrical cross-section about a radial line taken through the point of maximum groove depth.

14. A tyre and wheel rim assembly according to claim 1 or 13 wherein the groove has a smooth profile.

15. A tyre and wheel rim assembly according to Claim 1, wherein at least the base of the groove is roughened to increase the grip and thus the initial radial and axial location of the tip of the toe.

16. A tyre and wheel rim assembly according to Claim 1, wherein the axial length of the bead seat and toe of the tyre when the toe is straightened to extend in the axial direction for tyre fitting measured from the tip of the toe to the heel point, which point is the point of intersection of a line along the bead seating portion of the tyre and a line along the flange contacting portion of the bead, is less than the distance from the heel point on the rim measured along the bead seat and to the nearest point on the axially inboard face of the groove so that the toe will enter into engagement with the groove.

17. A tyre and wheel rim assembly according to Claim 1, wherein the axial distance from the vertical part of the flange to the centre line of the groove is at least as great as the axial distance from the flange contacting vertical part of the tyre bead to the end of the toe measured before the tyre is fitted to the wheel rim so that the toe will enter into engagement with the groove.

18. A tyre and wheel rim assembly according to Claim 17 wherein the said axial distances are in the range of 16 - 23 mm.

19. A tyre and wheel rim assembly according to Claim 17 wherein the said axial distances are both 20 mm.

20. A tyre and wheel rim assembly according to Claim 17 wherein the said axial distances are both 18 mm.

21. A tyre and wheel rim assembly according to Claim 1, 16, or 17 wherein a flat ledge is provided between the groove and the well.

22. A tyre and wheel rim assembly according to Claim 1, 16, or 17 wherein a groove is provided at either side of the wheel rim and a toe is provided on both tyre beads.

23. A tyre for mounting on a wheel rim having a pair of bead seats arranged one at each side thereof, a tyre fitting well, a circumferentially extending groove in said rim between at least one of said seats and the well, said tyre comprising a tread por-tion, side walls, and a pair of beads each containing a substan-tially inextensible annular reinforcement and each including an extended toe portion comprising elastomeric material and projecting axially and radially inwards of said tyre bead said toe portion being adapted to be flexible in a direction substantially perpendicular to its length and to be substantially rigid in the direction of its length.

24. A tyre according to Claim 23 wherein the toe portion includes a reinforcement layer extending around and adjacent to the outer surface of said toe portion.

25. A tyre according to Claim 24 wherein the reinforcement layer comprises a woven fabric.

26. A tyre according to claim 25 wherein the fabric is a cross-woven fabric and has both the warp and weft directions substantially at 45° to the radial direction.

27. A tyre according to Claim 24, 25 and 26 wherein the reinforcement layer comprises nylon.

28. A tyre according to Claim 23, 24 or 25 wherein the sidewall from the annular reinforcement towards the mid-sidewall region is reinforced so that said region resists bending.

29. A tyre according to Claim 23 wherein the tyre is a cross-ply tyre.

30. A tyre according to Claim 23 wherein the tyre is a radial ply having a radial ply carcass of steel or textile material and a breaker assembly of steel or textile material.

31. A tyre according to Claim 23 wherein the tyre is a belted bias tyre.

32. A tyre according to Claim 29, 30 or 31 wherein the tyre has an aspect ratio between 50 and 65%.

33. A tyre according to Claim 23, 24 or 25 wherein the tyre is of the type capable of running in a deflated condition without damage to the tyre.

34. A tyre and wheel rim combination capable of operating in a substantially deflated condition without the tyre becoming dislodged from its position on the rim comprising:
(a) a circular wheel rim having, in cross-section, a pair of radially outwardly extending flanges; a pair of bead seats immediately adjacent the flanges having a bead seat diameter in a first annular plane; a radially inwardly extending open well located between said bead seats, the depth of the open well from said first annular plane being at least as great as the radial height of the flanges above said plane so that a tyre can be mounted on the rim by use of the open well;
(b) a tyre mounted on said rim and defining there-with a chamber for inflation, said tyre having a tread portion and a pair of sidewalls terminating in a pair of beads fitted upon the rim bead seats, each tyre bead having a substantially inextensible annular bead reinforcement embedded therein; and a bead toe;
(c) means on said rim and tyre to prevent at least one of the tyre beads from being dislodged from its rim bead seat into the open rim well when the tyre is operated at normal driving speed in a deflated condition but permitting the tyre to be mounted on the rim bead seats by inflation pressure and demounted therefrom by exerting an axially directed force against the tyre bead, said means comprising a circumferential groove in the rim adjacent at least one bead seat in the area between the bead seat and the open well;
said means further comprising the bead toe extending axially inward of the bead and radially inwardly of said first annular plane and into its associated rim groove, said toe being flexible in a direction perpendicular to its length to allow tyre fitting and having substantial form stiffness in the direction of its length such that when an axially inward force at the tread portion is applied to the bead by the tyre sidewall in the ground contacting portion of the tyre cir-cumference, a substantial radially and axially outwardly directed force is generated at the annular reinforcement, the generated force tightening the annular reinforcement and retaining the bead.

35. A tyre and wheel rim assembly according to claim 34 wherein the toe form stiffness is enhanced by means of a reinforcement layer adjacent to the outer surface of said toe.

36. A tyre and wheel rim assembly according to claim 35 wherein the reinforcement layer extends from the tip of the toe around the axially inward surface of the toe to at least the radial height of the centre of the annular reinforcement.

37. A tyre and wheel rim assembly according to claim 35 wherein the reinforcement layer extends from the bead seat region of the bead around the toe and upwards along the axially inner surface of the toe to at least the radial height of the centre of the annular reinforcement.

38. A tyre and wheel rim assembly according to claim 35 wherein the reinforcement layer comprises at least one ply of material.

39. A tyre and wheel rim assembly according to claim 38 wherein the reinforcement ply comprises a fabric.

40. A tyre and wheel rim assembly according to claim 39 wherein the fabric is a cross-woven fabric.

41. A tyre and wheel rim assembly according to claim 40 wherein the fabric is of nylon.

42. A tyre and wheel rim assembly according to claim 39 wherein the fabric is a knitted fabric.

43. A tyre and wheel rim assembly according to claim 34 wherein the toe comprises an elastomeric material having a hardness when measured under laboratory conditions greater than 50° Shore.

44. A tyre and wheel rim assembly according to claim 43 wherein the hardness is in the range of 60 - 96° Shore.

45. A tyre and wheel rim assembly according to claim 34 wherein the radially inward edge of the bead seat of the wheel rim is smoothly radiused into the circumferential groove and the toe is profiled to a complementary shape.

46. A tyre and wheel rim assembly according to claim 34 wherein the circumferential groove has a symmetrical cross-section about a radial line taken through the point of maximum groove depth.

47. A tyre and wheel rim assembly according to claim 45 wherein the groove has a smooth profile.

48. A tyre and wheel rim assembly according to claim 34 wherein at least the base of the circumferential groove is roughened to increase the grip and thus maintain the initial radial and axial location of the tip of the toe.

49. A tyre and wheel rim assembly capable of operating in a substantially deflated condition without the tyre becoming dislodged from its position on the rim comprising;
(a) a circular wheel rim having, in cross-section a pair of radially outwardly extending flanges; a pair of bead seats immediately adjacent the flanges and at a first annular plane; a radially inwardly extending open well located between said bead seats, the depth of the open well from said first annular plane being at least as great as the radial height of the flanges above said plane so that a tyre can be mounted on the rim by use of the open well;
(b) a tyre mounted on said rim and defining there-with a chamber for inflation, said tyre having a tread portion and a pair of sidewalls terminating in a pair of beads fitted upon the rim bead seats, each tyre bead having a substantially inextensible annular bead reinforcement embedded therein; and a bead toe;
(c) means on said rim and tyre to prevent the tyre beads from being dislodged from the rim bead seats into the open well when the tyre is operated at normal driving speed in a deflated condition but permitting the tyre to be mounted on the rim bead seats, said means comprising a circumferential groove in the rim immediately adjacent at least one bead seat in the area between the bead seat and the open well; said means further comprising a bead toe extending axially and radially inwardly of said first annular plane and into its associated rim groove, said toe being flexible in a direction perpendicular to its length to allow tyre fitting and having substantial rigidity in the direction of its length, the axial length of the bead seat and toe of the tyre when the toe is straight-ened to extend in the axial direction for tyre fitting measured from the tip of the toe to the heel point, which point is the point of intersection of a line along the bead seating portion of the tyre and a line along the flange contacting portion of the bead being less than the distance from the heel point on the rim measured along the bead seat and to the nearest point on the axially inboard face of the groove so that the toe will enter into engagement with the groove when the tyre bead is positioned on its bead.

50. A tyre and wheel rim assembly according to claim 34 wherein said flanges are formed with a vertically oriented part and said tyre has a flange contacting vertical part, the axial distance from the vertically oriented part of the flange to the centre line of the groove is at least as great as the axial distance from the flange contacting vertical part of the tyre bead to the end of the toe measured before the tyre is fitted to the wheel rim so that the toe will enter into engagement with the groove.

51. A tyre and wheel rim assembly according to claim 50 wherein the said axial distances are in the range of 16 -23 mm.

52. A tyre and wheel rim assembly according to claim 50 wherein the said axial distances are both 20 mm.

53. A tyre and wheel rim assembly according to claim 50 wherein the said axial distances are both 18 mm.

54. A tyre and wheel rim assembly according to claim 34 wherein a flat ledge is provided between the groove and the well.

55. A tyre and wheel rim assembly according to claim 34 wherein a circumferential groove is provided at either side of the wheel rim and a toe is provided on both tyre beads.

56. A tyre and wheel rim assembly according to claim 34 wherein the radius of the tip of the toe measured before the tyre is fitted to the wheel rim is less than the radius of the base of the groove in the wheel rim such that upon assembly the tyre toe is precompressed into the groove.

57. A tyre and wheel rim combination capable of running when the tyre is in a substantially deflated condition without bead dislodgement comprising a tyre includ-ing a tread, sidewalls, a pair of beads, a substantially inextensible annular bead reinforcement embedded in each said bead, at least one of said beads having an axially and radially inwardly extending toe of generally triangular configuration, a circular one piece wheel rim having, in cross-section, a pair of radially outwardly extending flanges;
a pair of bead seats immediately adjacent the flanges having a bead seat diameter in a first annular plane; a redially inwardly extending open well located between said bead seats, the depth of the well from said first annular plane being at least as great as the radial height of the flanges above said plane so that a tyre can be mounted on the rim by use of the open well; means on said rim and tyre to prevent the tyre beads from being dislodged from the rim bead seats into the open rim well when the tyre is operated at normal driving speed in a deflated condition but permitting the tyre to be mounted on the rim bead seats by inflation pressure and demounted therefrom by exerting an axially directed force against the tyre bead, said means comprising a circumferential groove in said rim between a bead seat and the well for receiving said toe, said toe being made of elastomeric material having contour retaining capability so as to maintain its position in said groove against migration toward the well under the influence of forces transmitted to it from the tread by rotation of the annular bead reinforcement when the tyre is operated in deflated condition.

58. The combination of claim 57 in which the bead toe is of a material at least as hard as the elastomeric material of any other portion of the tyre.

59. The combination of claim 57 in which the bead toe is encased with a reinforcing material.

60. The combination of claim 59 in which the reinforcing material is a cross-woven fabric.

61. The combination of claim 60 in which the cross-woven fabric is of nylon and is positioned at a 45°
bias to the radial direction.

62. The combination of claim 57 in which the bead toe has in cross-section, the shape of a truncated triangle.

63. The combination of claim 62 in which the bead toe is at an angle to its bead seat so that a line extending from the projected apex of said truncated triangle and through the centre of said triangle will intersect the respective tyre bead reinforcement.

64. The combination of claim 57 in which the bead reinforcement in cross-section, is of generally square con figuration.

65. The combination of claim 57 including a triangular apex strip in the tyre sidewall and attached to the bead reinforcement.

66. A tyre and wheel rim combination capable of running when the tyre is in a substantially deflated condition without bead dislodgement comprising a tyre including a tread, sidewalls, a bead on each sidewall, a substantially inextensible annular bead reinforcement embedded in said bead, at least one of said beads having a toe portion of generally triangular configuration extending axially and radially inwardly of said bead;

said wheel rim having, in cross-section, a pair of radially outwardly extending flanges and an open well between said flanges of a radial depth at least as great as the radial height of said flanges so that a tyre can be mounted on the rim by use of the open well;
a pair of bead seats immediately adjacent the flanges;
at least one circumferential groove in the rim immediately adjacent a bead seat and positioned to receive said toe portion;
an intermediate rim portion between the groove and the well having a diameter equal to that of the bead seat;
said toe being flexible in a direction perpendicular to its length to allow fine fitting but having such form integrity in the direction of its length that when the tyre is operated in deflated condition with forces transmitted from the tread tending to rotate said annular bead reinforce-ment and move said at least one bead toward the open well, said form integrity will prevent the toe portion from deforming so that the bead region takes up a diameter large enough to move over said intermediate rim portion.

67. A tyre and wheel rim combination capable of operating in a substantially deflated condition without the tyre becoming dislodged from its position on the rim comprising;
(a) a circular wheel rim having, in cross-section, a pair of radially outwardly extending flanges; a pair of bead seats immediately adjacent the flanges having a bead seat diameter in a first annular plane; a radially inwardly extending open well located between said bead seats, the depth of the open well being at least as great as the radial height of the flanges above the bead seats so that a tyre can be mounted on the rim by use of the well;
(b) a tyre mounted on said rim defining therewith a single chamber for inflation, said tyre having a tread portion and a pair of sidewalls terminating in a pair of beads fitted upon the rim bead seats, each tyre bead having a substantially inextensible annular bead reinforcement embedded therein; and a bead toe;
(c) means on said rim and tyre to prevent at least one of the tyre bead from being dislodged from its rim bead seat into the open rim well when the tyre is operated at normal driving speed in a deflated condition but permitting the tyre to be mounted on the rim bead seats by inflation pressure and demounted therefrom by exerting an axially directed force against the tyre beads, said means comprising a circumferential groove in the rim, said groove being positioned immediately adjacent a bead seat with one side of said groove being formed as a radially inwardly curved extension of the adjacent bead seat, the groove having a smoothly curved bottom and being substantially symmetrical about a circumferential plane passing through the centre of its bottom; a rim portion between the groove and the open well approximately at the level of said first annular plane;
said means further comprising a radially and axially inwardly extended portion on the bead toe of the tyre, said toe portion extending radially inwardly of said first annular plane and into the adjacent rim groove so as to contact at least the axially outer side of the groove when the beads are normally seated on the rim bead seats; said toe portion being of an elastomeric material at least as hard as any other elastomeric portion of the tyre and encased in a cross-woven fabric immediately under the surface thereof with the fabric being positioned with its cords at about a 45° angle to the plane of the toe portion; said toe portion having the shape, in cross-section, of a truncated triangle and being at an angle to the tyre bead such that a line extending from the projected apex of said truncated triangle and passing through the centre of that triangle will intersect the respective annular bead reinforcement, said toe being flexible in a direction per-pendicular to its length to allow fine fitting and having substantial form stiffness in the direction of its length such that when an axially inward force at the tread portion is applied to the bead by the tyre sidewall in the ground contacting portion of the toe circumference, a substantial radially and axially outwardly directed force is generated at the bead reinforcement, the generated force tightening the bead reinforcement and retaining the bead.

68. A tyre for mounting on a circular wheel rim having, in cross-section, a pair of radially outwardly extending flanges; a pair of bead seats immediately adjacent the flanges having a bead seat diameter in a first annular plane; a radially inwardly extending open well located between said bead seats, the depth of the open well from said first annular plane being at least as great as the radial height of the flanges above said plane so that the tyre can be mounted on the rim by use of the open well; and a circumferential groove in the rim adjacent at least one bead seat in the area between the bead seat and the open well, said tyre being capable of running on a vehicle under a high applied side force without bead dis-lodgement and comprising a tread, a pair of sidewalls, a pair of beads, a substantially inextensible annular reinforcement embedded in each bead, at least one of said beads having an extended toe of generally triangular configuration as viewed in cross-section, one apex of said cross-section being axially and radially inwards of said annular reinforcement and the side of the triangular configuration opposite said one apex abutting the annular reinforcement whether the tyre be in repose, inflated, or operating in a substantially deflated condition with an applied side force, said toe being made of elastomeric material having the capability of bending per-pendicular to a line from said one apex to the annular reinforcement and having high capability to maintain its contour integrity and its length from the annular reinforce-ment to said one apex under the application to the bead of a rotational moment resulting from an axially inward force applied to the tyre tread under deflated running and causing a substantially radially and axially outwardly directed force on the bead to tighten the annular reinforcement and retain the bead whereby the toe can function in cooperation with a rim groove to prevent the bead from dislodgement and migrating to the well when operating deflated under said high side force condi-tions.

69. The tyre of claim 68 in which the toe has a reinforcing layer of fabric positioned adjacent to the surface of the toe and extending around the toe and bead from the bead seat region and upwards along the axially inner surface of the toe to at least the radial height of the annular re-inforcement.

70. The tyre of claim 69 in which the reinforcing layer of fabric is a woven fabric.

71. The tyre of claim 69 in which the reinforcing layer of fabric is a knitted fabric.

72. The tyre of claim 69 in which the reinforcing layer of fabric is nylon.

73. The tyre of claim 68 in which the elastic material of said toe is rubber at least as hard as any other rubber of which said tyre is composed.

74. The tyre of claim 68 in which said one apex of the generally triangular toe is truncated, the inner defining wall leading to said one apex being convex and the outer wall leading to said one apex being concave when the tyre is in a condition of repose.

75. A tyre and wheel rim assembly according to claim 34 in which the bead toe is shaped to have an inter-ference fit against the axial outer portion of the circum-ferential groove when the bead is normally seated on the rim bead seat.

76. A tyre and wheel rim assembly according to claim 34, 49 or 57 in which the tyre is a radial ply tyre.

77. A tyre and wheel rim assembly according to claim 66 or 67 in which the tyre is a radial ply tyre.

78. A tyre and wheel rim assembly according to claim 34, 49 or 57 in which the tyre is a cross-ply tyre.

79. A tyre and wheel rim assembly according to claim 66 or 67 in which the tyre is a cross-ply tyre.

80. A tyre and wheel rim assembly according to claim 34, 49 or 57 in which the tyre is a belted bias ply tyre.

81. A tyre and wheel rim assembly according to claim 66 or 67 in which the tyre is a belted bias ply tyre.

82. A tyre according to claim 68 in which the tyre is a radial ply tyre.

83. A tyre according to claim 68 in which the tyre is a cross ply tyre.

84. A tyre according to claim 68 in which the tyre is a belted bias ply tyre.

85. A tyre and wheel rim assembly according to claim 34, 49 or 57 in which the axially inward surface of the bead is convex towards the interior of the tyre from the toe tip to at least the radial height of the annular reinforce-ment.

86. A tyre and wheel rim assembly according to claim 66 or 63 in which the axially inward surface of the bead is convex towards the interior of the tyre from the toe tip to at least the radial height of the annular reinforcement.

87. A tyre and wheel rim assembly according to claim 67 in which the axially inward surface of the bead is convex towards the interior of the tyre from the toe tip to at least the radial height of the annular reinforcement.

88. A tyre and wheel rim assembly according to claim 34 in which the wheel rim includes, adjacent the radially outermost portion of each flange, a frusto-conical portion.

89. A tyre and wheel rim assembly according to claim 88 in which the tyre has an aspect ratio of less than 1.00 and has a radial ply carcass which in each sidewall follows, at least from the mid-sidewall to the annular bead reinforcement, the neutral equilibrium curve of a single ply radial carcass with no breaker subjected to inflation pressure, the curve being tangential relative to the annular bead reinforcements and being substantially parallel to the frusto-conical portions of the wheel rim in the regions adja-cent to said frusto-conical portions.

90. A tyre and wheel rim assembly according to claim 49 in which the wheel rim includes, adjacent the radially outermost portion of each flange, a frusto-conical portion.

91. A tyre and wheel rim assembly according to claim 90 in which the tyre has an aspect ratio of less than 1.00 and has a radial ply carcass which in each sidewall follows, at least from the mid-sidewall to the annular bead reinforcement, the neutral equilibrium curve of a single ply radial carcass with no breaker subjected to inflation pressure, the curve being tangential relative to the annular bead re-inforcements and being substantially parallel to the frusto-conical portions of the wheel rim in the regions adjacent to said frusto-conical portions.

92. A tyre and wheel rim assembly according to claim 57 in which the wheel rim includes, adjacent the radially outermost portion of each flange, a frusto-conical portion.

93. A tyre and wheel rim assembly according to claim 92 in which the tyre has an aspect ratio of less than 1.00 and has a radial ply carcass which in each sidewall follows, at least from the mid-sidewall to the annular bead reinforcement, the neutral equilibrium curve of a single ply radial carcass with no breaker subjected to inflation pressure, the curve being tangential relative to the annular bead reinforcements and being substantially parallel to the frusto-conical portions of the wheel rim in the regions adjacent to said frusto-conical portions.

94. A tyre and wheel rim assembly according to claim 66 in which the wheel rim includes, adjacent the radially outermost portion of each flange, a frusto-conical portion.

95. A tyre and wheel rim assembly according to claim 54 in which the tyre has an aspect ratio of less than 1.00 and has a radial ply carcass which in each sidewall follows, at least from the mid-sidewall to the annular bead reinforcement, the neutral equilibrium curve of a single ply radial carcass with no breaker subjected to inflation pressure, the curve being tangential relative to the annular bead reinforcements and being substantially parallel to the frusto-conical portions of the wheel rim in the regions adjacent to said frusto-conical portions.

96. A tyre and wheel rim assembly according to claim 67 in which the wheel rim includes, adjacent the radially outermost portion of each flange, a frusto-conical portion.

97. A tyre and wheel rim assembly according to claim 96 in which the tyre has an aspect ratio of less than 1.00 and has a radial ply carcass which in each sidewall follows, at least from the mid-sidewall to the annular bead reinforcement, the neutral equilibrium curve of a single ply radial carcass with no breaker subjected to inflation pressure, the curve being tangential relative to the annular bead re-inforcements and being substantially parallel to the frusto-conical portions of the wheel rim in the regions adjacent to said frusto-conical portions.

98. A tyre and wheel rim assembly wherein the tyre com-prises a tread portion, side walls and a pair of beads each containing a substantially inextensible annular reinforcement, at least one of said beads having an axially and radially in-wardly extending toe portion, the wheel rim having a pair of bead seats arranged one at each side thereof, a tyre fitting well, a circumferentially extending groove in said rim between at least one of said seats and the well, said groove serving to locate at least a portion of said toe portion, said toe portion being flexible in a direction perpendicular to its length and substantial rigidity in a direction parallel to its length thereby to provide contour retaining capability so as to maintain its position in said groove against migration toward the well under the influence of forces transmitted to it from the tread by rotation of the annular bead rein-forcement when the tyre is operated in deflated condition.

99. A tyre for mounting on a wheel rim having a pair of bead seats arranged one at each side thereof, a tyre fitting well, a circumferentially extending groove in said rim between at least one of said seats and the well, said tyre comprising a tread portion, side walls and a pair of beads each containing a substantially inextensible annular reinforcement, at least one of said beads having an axially and radially inwardly ex-tending toe portion, at least a portion of said toe portion being arranged to be located in said groove, said toe portion being flexible in a direction perpendicular to its length and substantial rigidity in a direction parallel to its length.