US3087528A

US3087528A - Reserve chamber tubeless tire

Info

Publication number: US3087528A
Application number: US712217A
Authority: US
Inventors: Herbert B Hindin; Leonard E Reinowski; Richard J Olejniczak
Original assignee: United States Rubber Co
Current assignee: Uniroyal Inc
Priority date: 1958-01-30
Filing date: 1958-01-30
Publication date: 1963-04-30
Anticipated expiration: 1980-04-30
Also published as: FR1213962A; BE573675A; GB843589A

Description

April 30, 1963 H. a. HlNDlN ETAL RESERVE CHAMBER TUBELESS TIRE Filed Jan. 30, 1958 3 Sheets-Sheet 1 INVENTORS HERBERT B. HlNDlN LEONARD E. REINOWSKI BY RICHARD J. OLEJNICZAK ATTORNEY.

April 30, 1963 H. B. HINDIN ETAL RESERVE CHAMBER TUBELESS TIRE 3 Sheets-Sheet 2"? Fi led Jan. 50, 1958 INVENTORS HERBERT B. HINDIN LEONARD E. REINOWSKI BY RICHARD J. OLEJNICZAK \QMXMZ ATTORNEY April '30, 1963 H. B. HINDIN ETAL RESERVE CHAMBER TUBELESS TIRE 3 Sheets-Sheet 3 Filed Jan. 30, 1958 JNVENTORS HERBERT a HINDIN LEONARD E. REINOWSKI BY RICHARD J. OLEJNIGZAK ATTORNEY.

Unite States 3,087,528 RESERVE CHAMBER TUBELESS TIRE Herbert B. Hindin, Grosse Pointe Woods, Leonard E.

Reinowslri, Mount Qlemens, and Richard J. Olejnicaalc,

East Detroit, Mich, assignors to United States Rubber Company, New York, N.Y., a corporation of New Jersey Fiied Jan. 30, 1958, Ser. No. 712,217 7 Claims. (Cl. 152-460) This invention relates to pneumatic tires of the tubeless type, and more particularly to a tubeless tire having means cooperating therewith to form a reserve air chamber for emergency use in the event of failure of the tire due to a puncture, blowout, or the like.

Recently, and particularly since the advent of tubeless tires, there has been an increasing demand by automotive engineers for some means, such as a new type of tire, which would eliminate the necessity for the customary spare tire and wheel, and thus give greater freedom in body styling and provide more luggage space in the rear trunk or compartment.

Heretofore, tire manufacturers have attempted to eliminate the need for a spare tire and wheel in various ways; as, for instance, by a diaphragm within the tire, dividing the same into outer and inner compartments which are separately inflated or connected by slow-leaking valves. Thus, when the outer compartment of the tire is punctured or otherwise ruptured, the air retained in the inner compartment prevents a complete collapse of the tire and permits the driver to bring the vehicle to a safe stop, or possibly drive the car a sufiicient distance to reach its destination or a service station where it can be repaired. This presumably would eliminate the need for a spare tire and avoid the necessity of making a roadside change of tires.

However, considerable difficulty has been experienced with diaphragm or dual compartment tires of this type. In one brand of these tires now on the market, the diaphragm is provided with beads at its edges which are seated on ledges extending inwardly from the inner Wall of the tire adjacent the bead portions thereof. In another brand, the diaphragm is held in place by extending the edges thereof between the beads of the tire and the portion of the rim upon which the tire is mounted.

Both of these types of tires are diflicult to mount, and much care must be exercised to insure that the diaphragm in each instance is properly positioned and anchored prior to inflation. Installation of the diaphragm and mounting of the tire must be done strictly in accordance with the prescribed instructions, otherwise the desired performance will not be attained.

There are other serious disadvantages to diaphragm tires of this type. For instance, one of the most common types of tire failures is a tread puncture, which results in a loss of air in the outer chamber. When this occurs, the underside of the crown portion of the tire comes into engagement with the diaphragm, and upon rotation of the tire, causes an abrasion of the diaphragm. This is due to the differences in the molded circumferences of the tire and diaphragm, and results in ultimate failure of the diaphragm and/or tire casing. Also, the puncturing object, if it extends through the tread, will subsequently puncture the diaphragm. This will cause a complete collapse of the tire, which, if the tire is run further, will cause serious damage to both the tire casing and the diaphragm.

Various other objections and problems present themselves in the use of diaphragm tires of the types described above. In a construction where the two chambers are separably inflated, extreme care must be exercised to insure the proper inflation of both chambers, otherwise it is possible to induce severe buckling of the diaphragm. Also, if the tire becomes soft, care must be exercised to make certain whether one or both of the chambers require additional air. Also, any dislodgment of the diaphragm out of proper concentric relation with the tire casing will cause an out-of-balance condition in the tire.

From the foregoing, it will be apparent that the dual chamber or diaphragm type of tires now in use are not entirely satisfactory, and are not sufliciently dependable to justify the elimination of the spare tire and wheel; and, therefore, some other more reliable and trouble-free tire must be found before the conventional spare tire and wheel can be safely dispensed with.

It is, therefore, a primary object of this invention to provide an otherwise conventional tubeless tire with means cooperating therewith to form an additional or reserve air chamber, inoperative during the normal operation of the tire, but adapted for emergency use in the event of tire failure, to permit reinflation of the tire.

The principal objects of the invention are attained by providing a substantially conventional tubeless tire with a flexible, fabric reinforced, air impervious wall or partition permanently adhered to the tire liner stock circum'ferentially of the tire intermediate the crown and bead portions thereof, and adapted for movement from a position within the well of the tire rim to a position engaging the inner crown area of the tire.

Another object of the invention is to provide a movable wall or partition of the character described which may be moved by inflation through the conventional rim valve from its normal or collapsed position within the rim area to its other or extended position in engagement with the crown area of the tire, to provide an emergency air chamber inside the tire, despite a previous failure due to a puncture, blowout, or the like.

Still another object of the invention is to provide a movable wall or partition member of the character described which is fashioned or shaped to the contour of the crown area of the tire, during the shaping and vulcanization of the tire, so that when the two are in engagement, relative movement therebetween, and consequent chafing, is reduced to a minimum and deleterious heat build-up is substantially eliminated. Inasmuch as the wall or partition member is shaped and cured with the the during the shaping and vulcanization of the latter, no additional molds and shaping and curing apparatus are necessary as is the case where separate diaphragms are used.

Inasmuch as the wall or partition member is normally in its collapsed condition nested within the rim until extended by inflation into engagement with the crown area of the tire, a further object of the invention is to provide means for inducing predetermined folds or pleats in the wall member so that the wall member when collapsed may uniformly accommodate itself to the smaller diameter of the rim well. Thus, bunching or uneven distribution of the wall member, which might cause an out-of-balance condition in the tire, is prevented.

A still further object of the invention is to provide a tubeless tire of the character described in which the wall or partition member is normally located in the tire in a position remote from, or out of proximity to, the crown region of the tire, and thus is not exposed to injury from puncturing objects or blowouts.

Still another object of the invention is to provide a tubeless tire of the character described in which the emergency wall or partition normally extends into the rim area of the wheel, and thus acts in a manner similar to an inner tube to prevent accidental roll-01f of the tire, and also seals against possible leakage of air at the bead portions of the tire. Furthermore, the emergency wall in its collapsed position seals the air chamber of the tire against failures due to bead wire separation, bead wire cuts, and carcass breaks above the bead.

Another object of the invention is to provide a tubless tire of the character described in which the reserve chamer forms an integral part of the tire, thus eliminating the mounting difliculties inherent in tires provided with separate diaphragms, and also in conventional tubeless tires. Conventional tubeless tires cannot be inflated until the beads are in substantial sealing engagement with the rim and rim flanges. This requires special equipment or tools and some effort on the part of the operator. With the present invention the tire beads may be forced into engagement with the rim flanges and thus properly mounted by inflating the tire through the sidewall valve.

The above and other objects and advantages, and the novel details of construction of this invention will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawing wherein:

FIG. 1 is a transverse sectional view of a tire and rim assembly embodying the present invention, with the emergency wall or partition member in its normal or collapsed position;

FIG. 2 is a similar view showing the emergency wall member in its extended position;

FIG. 3 is a circumferential sectional view of a tire and rim assembly showing the emergency wall member in the position illustrated in FIG. 1;

FIG. 4 is a fragmentary partial sectional perspective view of the tire of this invention with the emergency wall member in the position illustrated in FIG. 1;

FIGS. 5, 6, 7, 8, 9 and 10 are partial sectional views showing one method of fabricating the emergency wall member on a building drum;

FIG. 11 is an elevational view of a building drum with the two plies of the emergency wall applied thereto and showing one stage of the fabrication of the tire of this invention;

FIG. 12 is a fragmentary partial sectional view showing the tire carcass and emergency wall member assembled on the tire building drum prior to the shaping and vulcanization thereof, and

FIGS. 13 and 14 are fragmentary sectional views showing modifications of the manner in which the emergency wall member is attached to the liner of the tire.

Referring now to the drawings, and more particularly to FIGS. 1 and 2 thereof, the numeral 10 indicates generally a tubeless type pneumatic tire of the so-called straight sidewall type comprising a tread portion 11, sidewalls 12, a carcass 13 usually composed of a plurality of plies 14 (see FIG. 12) of cord fabric skimcoated with conventional carcass stock, and bead portions 15, provided with substantially inextensible bead wires 16. The reference character 17 indicates a liner in the form of a sheet of air impervious material extending throughout the interior of the tire from one bead portion to the other. The reference character 18 indicates a conventional type of drop center rim upon which the tire is mounted. The rim 18 is provided with an inflating valve 19 and the reference character 20 indicates an inflating valve located in the sidewall of the tire. The

valves

19 and 20 may be of any preferred or desired construction, it being essential only that both of these valves have an air-tight connection with the rim or tire structure with which they are respectively associated. If desired, the rim valve 19 may be replaced by a valve (not shown) similar to valve 20 located in the tire sidewall in a position to permit inflation of the chamber between the rim 18 and partition 25.

The tire construction thus far described, except possibly for the sidewall valve 20, is a conventional type of tubeless pneumatic tire now quite generally in commercial use. The present invention relates to a simple, but effective, means, useful upon tire failure, to convert the tubeless tire into a partial or semitube type tire, whereupon it may be reinflated and driven to its destination or to a service station where it can be repaired.

To this end, the invention consists in the provision of a flexible, fabric reinforced, air impervious, wall or partition 25, permanently adhered during vulcanization of the tire to the inside of the tire circumferentially thereof intermediate the crown and bead portions of the tire. This wall or partition 25 is preferably formed of two plies of nylon cord fabric, each ply of which is skimcoated on each side with a suitable rubber stock to render the same air impervious. By way of example, but not by way of limitation, the skimcoat may be composed of an admixture of styrene butadiene rubber, natural rubber and rubber reclaim. This wall or partition 25, sometimes referred to herein as an emergency wall, is preferably formed of two plies with the cords of the plies extending in opposite directions at an approximate angle of from 55 to 65 to the circumferential center line of the tire building drum upon which the wall member 25 is fabricated. After the wall or partition member is shaped these cords extend at an approximate angle of from 30 to 45 to the circumferential center line of the tire.

The circumferential marginal edges of the wall member 25 are adapted to be permanently secured to the liner 17 of the tire during vulcanization of the tire. As stated, the emergency wall member preferably comprises two

plies

26 and 27, and in fabricating the wall member 25 with the liner 17, as shown in FIGS. 5 to 11, the

marginal edges

26a and 27a of the

plies

26 and 27 are folded to extend in opposite directions; i.e., towards the bead and crown portions of the tire, respectively, to provide a fold line 28 at each side of the tire about which the emergency wall member 25 moves from its position shown in FIG. 1 to the position shown in FIG. 2.

The dimensions or surface extent and shape of the Wall member 25 between the points of attachment or fold lines 28 are such that in one position, as shown in FIG. 2, the Wall member will engage the crown area of the tire in a relaxed condition. In its other position it will lie within the well of the rim :as shown in FIG. 1 in an extended condition along the RIG. 1 cross-section of the tire and rim. If the Wall member 25 is formed of extensible material, its dimensions and points of attachment can be such that the wall member will be in a relaxed condition when in engagement with the crown of the tire (FIG. 2) and in a stretched condition when in the position shown in FIG. 1. This will compensate for the difference between the diameters of the tire crown and rim.

With the wall member in the position shown in FIG. 1 the tire cavity above the wall member 25 has been inflated through the sidewall valve 20, and the tire is functioning as a conventional tubeless tire. However, in this position of the parts, the tire has the added advantage that with the wall member 25 extending into the rim, the wall member acts in a manner similar to an inner tube to prevent accidental roll-off of the tire and also seals against leakage of air at the bead portions of the tire and other failures at or above the beads.

In the event of failure of the tire due to a puncture, blowout or the like, which causes deflation of the tire cavity above the emergency Wall 25, the tire can he reinflated through the rim valve 19 to move the emergency Wall from the position shown in FIG. 1 to that shown in FIG. 2. When the wall 25 is in this position, it spans and seals off the punctured or damaged portion of the tire casing and cooperates with the tire and rim to form a second or reserve chamber which will hold air despite the damage to the tire, and enable the car to reach its destination or a service station for repair. This second or reserve inflatable chamber is substantial equal in volume to that of the tire before failure.

In fabricating the tire of this invention the emergency wall or partition member is applied to the building drum as the first and second plies, and the marginal edges are prepared for attachment to the tire sidewalls and for in- =ducing predetermined folds or pleats in the manner shown in FIGS. 5 to 11, inclusive. As shown in FIG. 5, the first ply 26 of bias-cut, skimcoated, nylon cord fabric is applied on a conventional building drum B and then spliced in the customary manner. As shown in FIG. 6, the edges of the ply 26 are then masked by the application of strips M of suitable masking material, such as sheet polyethylene. Thereafter, the second ply 27 formed of bias-cut, skimcoated, nylon cord fabric is applied to the building drum and properly spliced and stitched to the ply 26; see FIG. 7. The cords in the second ply 27 extend in an opposite direction to the cords in ply 26. The second ply 27 is somewhat wider than the first ply 26, and the marginal edges of the two plies are separated by the masking strips M.

As pointed out heretofore, in some cases it is desirable to provide means for inducing predetermined folds or pleats within the wall member, and this is accomplished by the manner in which the marginal edges of the wall member are attached to the sidewalls of the tire. As shown in FIGS. 8 and 11, diamond-shaped masking patches P of polyethylene or the like are applied to ply 27 at both ends thereof at equi spaced points. circumferentially with the patches at one end of the ply being in alignment with those at the other end. The patches P are centered so as to extend equal distances from both sides of a line FF, FIG. 8, which later becomes the major fold line 28 at each side about which the emergency wall 25 moves from the position shown in FIG. 1 to that shown in FIG. 2. This fold line is established at the inner edge of the masking strips M at both ends of the

plies

26 and 27.

After the masking patches P have been applied as above described, the top or exposed surface .of the second ply 27 is coated with a butyl cement. This butyl cement may, by way of example but not by way of limitation, be composed of 1 /2 percent raw butyl and gasoline in which the butyl is dissolved or dispersed. This butyl cement prevents adhesion between the exposed surface of ply 27 and the inner liner of the tire during vulcanization, but does not destroy the building tack of this surface.

After the application of this butyl cement, the patches P are removed and the marginal edges 27a of ply 27 are folded back upon the ply 27, as shown in FIG. 9 along the line FF which coincides with the major dimension of the diamond shaped patches P. The opposed surfaces of the folded back portion between the line FF and the line GG, which were masked or protected during the application of the butyl solution, will be vulcanized to one another during the vulcanization of the tire, and thus will form substantially triangular-shaped areas 29 of double thickness. These substantially triangular-shaped areas produce angular fold lines 30, see particularly FIGS. 3 and 4, extending radially outwardly beyond the genenal or major f-old line 28 at each side of the emergency Wall, and thus Will induce the formation of pleats or folds =31 which enables the emergency wall member, when collapsed, to uniformly accommodate itself to the smaller diameter of the rim well.

When the masking strips M are removed, filler strips 32 of rubber material are applied around the drum immediately adjacent fold line F-F; see FIG. 10. These filler strips fill in the voids between the liner 17 (shown in dotted lines in FIG. and the double thickness of material at the fold line FF. x 1

When the liner 17 is applied to the building drum, as indicated by dotted lines in FIG. 10, the top surfaces of the

marginal portions

26a and 27a of the

plies

26 and 27 engage the liner material, and during vulcanization of the tire are permanently united therewith. The marginal portions 26a extend in the direction of the tire beads and the marginal portions 27a extend in the direction of the crown of the tire. This forms a substantially T- shaped connection between the edges of the emergency wall 25 and the liner 17 of the tire, so that any forces exerted by movement of the emergency wall from one of its extreme positions to the other will always be in shear on one ply of the wall member. However, the size and shape of the wall member 25 between the points of attachment to the side walls of the tire is such that there is little, if any, strain at the points of attachment in either position of the wall member.

As illustrated in FIG. 13, the

marginal edges

26b and 27b of the wall member 251) are folded along the fold line 28b so as to extend towards the beads of the tire. In -FIG. 14 the edges 26c and 270 of the wall member 250 are folded along the fold line 28c so as to extend towards the crown of the tire.

From the foregoing it will be apparent that with the present invention a conventional tubeless tire can be provided with a second or reserve a-ir chamber, rendered operative, when necessary, by inflation through the standard rim valve. When not functioning as a second or reserve chamber, the emergency wall member lies substantially within the rim and, therefore, does not affect the operation of the tire as a tubeless tire. However, in its inoperative position, the emergency Wall member acts in a manner similar to an inner tube to prevent accidental roll-off of the tire, and also seals against leakage of air at the bead portion of the tire and other failures at or above the bead. A tire constructed in accordance with this invention can be readily fabricated on a conventional building drum and shaped and cured in the same manner as other types of tires. Also, tubeless tires of this construction may be more readily mounted upon the rim, because it is unnecessary to establish a subtantially airtight seal between the beads and the rim prior to inflation.

Obviously, the emergency chamber may be inflated by .a hand pump, or by the air hose at a service station, if one is available. However, for emergency use, the car owner may be provided with a cylinder of some gas under pressure, such, for instance, as CO provided with a discharge nozzle suitable for attachment to the rim valve of the tire.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

Having thus fully described our invention, what we claim and desire to secure by Letters Patent of the United States is:

1. The combination with a pneumatic tubeless tire having bead portions and a tire supporting rim upon which said bead portions are seated, of a flexible wall member attached at its marginal edges to the inside of the tire circumferentially thereof at a point intermediate the crown and bead portions of the tire and movable from a position within the rim to a position in engagement with the crown area of the tire, said wall member being adapted to engage the crown area of the tire in a substantially relaxed condition, inflation openings formed in said tire and said rim and arranged to permit inflation of the tire on either side of said -wall member for selective movement of said wall member to either of its positions aforesaid, the marginal edges of said wall member being attached to the tire wall in a manner to induce predetermined circumferentially-spaced transverse folds in said Wall member in its collapsed position whereby said wall member may uniformly accommodate itself to the smaller diameter of the rim.

2. In combination with a pneumatic tire of the tubeless type having bead portions mounted on a tire supporting rim, means comprising a flexible, air impervious wall member attached at its marginal edges to the inside of the tire circum-ferentially thereof between the crown and bead portions of the tire, said wall member being substantially nonstretchable and formed of at least two oppositely laid plies of bias-cut rubberized cord fabric,

said wall member being adapted to lie within the rim area in relaxed condition to prevent accidental roll-off of the tire and to seal against leakage of air at the bead portions of the tire, said wall member being also adapted to be moved by inflation to another position wherein it will engage the inner crown area of the tire in a relaxed condition and in essentially smooth contact therewith, to cover any damaged area in the tire and to provide a second air chamber for emergency use, and inflation openings formed in said tire and said rib and arranged to permit inflation of the tire on either side of said wall member for selective movement of said wall member to either of its positions aforesaid.

3. In combination with a pneumatic tire of the tubeless type having bead portions mounted on a tire supporting rim, means comprising a flexible, air-impervious wall member attached at its marginal edges to the inside of the tire ciroumferentially thereof between the crown and bead portions of the tire, said wall member being substantially nonstretchable and formed of at least two oppositely laid plies of bias cut rubberized cord fabric shaped to the contour of the inner crown area of the tire, said Wall member being adapted to lie within the rim area in relaxed condition to prevent accidental roll-off of the tire and to seal against leakage of air at the bead portions of the tire, said wall member being also adapted to be moved by inflation to another position wherein it will engage the inner crown area of the tire in a relaxed condition and in essentially smooth contact therewith, to cover any damaged area in the tire and to provide a second air chamber for emergency use, and inflation openings formed in said tire and said rim and arranged to permit inflation of the tire on either side of said wall member for selective movement of said wall member to either of its positions aforesaid.

'4. In combination with a pneumatic tire of the tubeless type having bead portions mounted on a tire supporting rim, means comprising a flexible, air-impervious wall member attached at its marginal edges to'the inside of the tire circumferentially thereof between the crown and bead portions of the tire, said wall member being substantially nonstretchable and formed of at least two oppositely laid plies of bias-cut rubberized cord fabric shaped to the contour of the inner crown area of the tire during the shaping of the tire, said wall member being adapted to lie within the rim area in relaxed condition to prevent accidental roll-off of the tire and to seal against leakage of air at the bead portions of the tire, said wall member being also adapted to be moved by inflation to another position wherein it will engage the inner crown area of the tire in a relaxed condition and in essentially smooth contact therewith, to cover any damaged area in the tire and to provide a second air chamber for emergency use, and inflation openings formed in said tire and said rim and arranged to permit inflation of the tire on either side of said wall member for selective movement of said wall member to either of its positions aforesaid.

5. -A pneumatic tubeless tire and rim combination comprising a rim and a reinforced casing having an outer tread surface, sidewalls, a bead at each inner sidewall edge and an opening between said beads, said casing mounted on the rim with said beads in sealing engagement with the sides of said rim; and a diaphragm of substantially nonstretchable, flexible, air-impervious material having lateral margins attached to the inside of each said sidewall at a position spaced from said beads, inflating means communicating with the interior of said casing through the rim and through the casing thereof respectively for selective movement of said diaphragm to a position around the inside of said casing and to a position to extend through said opening to engage the interior surface of said rim, and said diaphragm being of a shape and size between the lateral mar-gins thereof to extend into said positions in a substantially relaxed condition so as to define with said tire an inner chamber operative to maintain said tire in fully inflated condition.

6. A pneumatic tubeless tire and rim combination comprising a rim and a reinforced casing having an outer tread surface, sidewalls, a bead at each inner sidewall edge and an opening between said beads, said casing mounted on the rim with said beads in sealing engagement with the sides of said rim; and a diaphragm of substantially nonstretchable, flexible, air-impervious material having lateral margins attached to the inside of each said sidewall at a position between said beads and tread surface, inflating means formed in said tire and said rim and communicating with the interior'of said casing on both sides of said diaphragm for selective movement of said diaphragm to a position around the inside of said casing and to a position to extend through said opening to engage the interior surface of said rim, and said diaphragm being dimensioned between the lateral margins thereof to extend into said positions so as to define with said tire an inner chamber operative to maintain said tire in fully inflated condition.

7. A pneumatic tubeless tire and rim combination comprising a rim and a reinforced casing having an outer tread surface, sidewalls, a head at each inner sidewall edge and an opening between said beads, said casing mounted on the rim with said beads in sealing engagement with the sides of said rim; and a diaphragm of clastomeric material having lateral margins attached to the inside of each said sidewall at a position spaced from said beads, inflating means communicating with the interior of said casing through the rim and through the casing thereof respectively for selective movement of said diaphragm to a position around the inside of said casing and to a position to extend through said opening to engage the interior surface of said rim, and said diaphragm being of such material and width between the lateral margins thereof as to be disposed in said positions in an extended condition along a given cross-section of the tire and rim so as to define with said tire an inner chamber operative to maintain said tire in fully inflated condition.

References Cited in the file of this patent UNITED STATES PATENTS 616,516 Wilson Dec. 27, 1898 1,342,297 Prudhornme June 1, 1920 2,779,380 King et a1 Jan. 29, 1957 2,942,642 Pond June 28, 1960 FOREIGN PATENTS 20,991 Great Britain of 1892 OTHER REFERENCES Tires-TBA Merchandising, June 1956, page 47, Two Chamber Safety Tires, cited as Tires.

Claims

1. THE COMBINATION WITH A PNUEMATIC TUBELESS TIRE HAVING BEAD PORTIONS AND A TIRE SUPPORTING RIM UPON WHICH SAID BEAD PORTIONS ARE SEATED, OF A FLEXIBLE WALL MEMBER ATTACHED AT ITS MARGINAL EDGES TO THE INSIDE OF THE TIRE CIRCUMFERENTIALLY THEREOF AT A POINT INTERMEDIATE THE CROWN AND BEAD PORTIONS OF THE TIRE AND MOVABLE FROM A POSITION WITHIN THE RIM TO A POSITION IN ENGAGEMENT WITH THE CROWN AREA OF THE TIRE, SAID WALL MEMBER BEING ADAPTED TO ENGAGE THE CROWN AREA OF THE TIRE IN A SUBSTANTIALLY RELAXED CONDITION, INFLATION OPENINGS FORMED IN SAID TIRE AND SAID RIM AND ARRANGED TO PERMIT INFLATION OF THE TIRE ON EITHER SIDE OF SAID WALL MEMBER FOR SELECTIVE MOVEMENT OF SAID WALL MEMBER TO EITHER OF ITS POSITIONS AFORESAID, THE MARGINAL EDGES OF SAID WALL MEMBER BEING ATTACHED TO THE TIRE WALL IN A MANNER TO INDUCE PREDETERMINED CIRCUMFERENTIALLY-SPACED TRANSVERSE FOLDS IN SAID WALL MEMBER IN ITS COLLAPSED POSITION WHEREBY SAID WALL MEMBER MAY UNIFORMLY ACCOMMODATE ITSELF TO THE SMALLER DIAMETER OF THE RIM.