FR2470697A1 - TIRES WITH SIDEWALLS COMPRESSED - Google Patents

Abstract

THIS TIRE IS REINFORCED SO THAT IT CAN RUN WITHOUT DAMAGE IN THE DEFLATED STATE. IT INCLUDES A TREAD 12 JOINED TO THE SHOULDERS 14 WHICH ARE JOINED TO THE SIDES 16 BY JOINING ZONES 22. THE SIDES ARE INCLINED AXIALLY AND RADIALLY TOWARDS THE INTERIOR BETWEEN 22 AND THE RIM 20 AND THE SHOULDERS ARE INCLINED RADIALLY TOWARDS L 'INSIDE AND AXIALLY OUTSIDE FROM TREAD 12 TO JUNCTION ZONES 22. A CARCASE EXTENDS INTO JUNCTION ZONES, SHOULDERS AND TREAD, AND SHOULDERS ARE REINFORCED BY RIBS 49 CIRCUMFERENTIALLY SPACES THAT RESIST SHOULDER FLUSHING ON THE GROUND WHEN THE TIRE IS ROLLING IN THE DEFLATED STATE AND UNDER NORMAL LOAD.

Description

The present invention relates to tires

  whose sides are subject to compression and more special-

  tires suitable for working in a state of

  inflated. Conventional tires have a reinforcement structure

necessarily composed of one or more layers, which extends

carcass turn, from one heel to another. In the absence of a

  such structure, the tires would tend to. "large-

  sir ". that is to say to expand outwards when

  pressurizes their interior cavity, without resistance

tance opposes this deformation. In recent years, a sidewall tire under compression has been developed which has eliminated the need for cords.

  reinforcement in the flank and heel regions.

  Since these regions are devoid of such cords, the manufacture of this type of tire is particularly well suited for the application of processes such as

  molding, casting or injection molding.

  In a sidewall tire subjected to compression, each

that sidewall is constructed so that its section, taken in a radial plane, has a concave external surface and a convex internal surface. The term “radial plane” is understood here to mean a plane which contains the axis of rotation of the tire. For the operation of a tire with sidewalls subjected to compression,

the flanks must be retained between the january

  te at one end and a means of restraint such as a belt

tread at the other end. When the case

  inner tire life is inflated to normal inflation pressure, inner forces due to pressure

  air acting against the sides tends to compress

  sea the elastomeric material of the sides. If the elastic material

  mother is compressed beyond a certain point, the forces in-

  posterior constrain the sides to expand axially towards

  outside. The flanks must therefore have characteristics

  sufficient bending stiffness and curvature

thickness, in accordance with the rules of the art, to resist this resulting force so that the sides can be retained. The main problem which has to be solved in the case of tires with sidewalls subjected to compression as well as in the case of conventional tires during rolling in the deflated state, resides in the destructive heat which

  results from friction between the internal surfaces of the tire

  tick during the movement of each part of the tire-

  matic through the tire imprint.

Another problem - which we have to solve in the case

sidewall tire subjected to compression which rolls in the

  deflated state consists in the friction of the region of the

  laps and flanks on the ground. This friction occurs because the parts of the shoulders and flanks located radially inward relative to the tread

  have a circumference smaller than that of the tread

  lement. All parts of the tire must rotate

the same angular velocity and therefore the li

part of the sidewalls and shoulders which are in contact with the ground when the tire is deflated, must

be greater than the linear speed of the tread

  is lying. There is therefore produced in these conditions a friction

  sides and shoulders on the ground.

  With the construction according to the invention, the pneumati-

that is reinforced in a way that minimizes the a-

brasion and friction from deflated tires. The shoulders of the tire also extend outside

so that the sides bend in an orderly fashion

  the bearing in the deflated state and are located axially outside the rest surfaces of the rim. The term "axially" is used in this specification as well as

  in the claims for designating a parallel direction

  to the axis of rotation of the tire. The term "radially" designates a direction perpendicular to the axis of rotation of the tire.

If internal contact occurs between various

  the tire during rolling in the deflated state, the tire is produced in such a way that this contact occurs practically between the sidewalls and the shoulders.

The shoulders have a configuration such that they are so-

  killed radially inward relative to the tread, so that the resulting abrasion that occurs between the internal surfaces is reduced. The shoulders are also provided with stiffening ribs which serve

  keep them out of contact with the ground while driving

tire in the deflated state. This helps to eli-

undermining the friction while causing only a minimum increase in weight. These ribs give the tire a hooping characteristic in the regions where the sidewalls and

the shoulders meet (joining parts) to con-

  serve the tall form of the shoulders o We understand by "character-

fretage "resistance which results from the application

  cation of a bandage or hoop around an object. This

  hooping also helps to maintain the flanks.

  In short, one aspect of the invention relates to a pneumatic tire.

  that capable of rolling in the inflated and deflated state, which comprises an annular body of elastomeric material, a circumferential tread, intended to come into contact with the ground, which extends at the periphery of the body, two shoulders which are joined to the tread and which extend axially outward and radially inward from the tread to two joining areas, two sides extending radially and axially inward interior from the junction zones up to two spaced mounting zones provided for the

mounting the tire on a rim, a reinforcement structure

  flat, continuous in the circumferential direction which extends between the two junction zones, several reinforcing ribs spaced circumferentially on at least one face of each of the shoulders, these ribs extending

from the junction zones to the tread.

According to another aspect, the invention relates to a

tire capable of rolling in the inflated state and in the

  inflated which comprises an annular body of elastomeric material, a circumferential tread intended to come into contact with the ground, which extends to the outer periphery of the body, two shoulders which are joined to this band of

bearing and extend axially outward and radiate

  inward from the tread

  up to two joining zones, two flanks which extend relatively

  dialing and axially inwards from the junction zones to two spaced mounting zones provided for mounting the tire on a rim, a structure

  reinforcement with continuous ply in the circumferential direction

  radial, which extends between the junction zones, and at least one continuous reinforcement rib in the circumferential direction, provided on the external surface of each of the junction zones, this rib entirely surrounding

the tire.

  According to another aspect, the invention relates to a

tire capable of rolling in the inflated state and in the

inflated, which comprises an annular body of elastomeric material, a circumferential tread, intended to come into contact with the ground, formed at the periphery of this body,

  two shoulders joined to the tread, which extends

  tooth axially outward and radially inward

laughing from the tread to two areas

  junction, two sides which extend radially and axially

  inward, from the junction areas to

  only two spaced mounting areas provided for mounting

  on a rim, a continuous reinforcement structure

pe in the circumferential direction, which extends between

  the junction zones, this nap-reinforced structure

  pe comprising at least two superimposed layers of cables of

reinforcement that extend from the tread-

up to the junction zones, the cables of one of the superimposed layers being inclined in the opposite direction from the cables of the other of the superimposed layers, and the cables of the superimposed layers being inclined at an angle of 35 to 550 by

relative to the median circumferential plane of the tire.

According to another aspect, the invention relates to a tire with sidewalls subjected to compression capable of rolling

in the deflated state.

  According to another aspect, the invention relates to a

pneumatic which can be easily manufactured by processes

  dice such as molding, casting or injection molding

tion.

  According to yet another aspect, the invention aims to

jet a reinforced tire structure intended to support

  wear the shoulders and flanks during the rollover

  inflated and deflated state.

Other characteristics and advantages of the invention

will appear during the description which follows. To the

attached drawings, given only by way of example, - FIG. 1 is a partial sectional view along a radial plane of a tire according to the invention, this view showing the tire in the unloaded and inflated state, mounted on a rim; - Fig. 2 is a section on a larger scale of a part of the tire, along the line II-II of FIG. 1; - Fig. 3 is a partial sectional view similar to that of FIG. 1, which shows the tire under normal load in the deflated state

  - Fig. 4 is a partial view of the road strip.

  Also, along line IV-IV of FIG. 1, with partial removal, for. show the relative angular arrangement of

of the protector and the reinforcement plies.

As indicated in FIG. 1, the invention relates to a tire 10 of the pneumatic type which comprises a

  tread 12 arranged circumferentially, intended

  born to come into contact with the ground, two shoulders 14

  nis to the tread and two sidewalls 16 which ends

nent by two mounting zones 18 intended to cooperate with a rim 20. Two junction zones 22 connect the shoulders-

  ment 14 on the sidewalls 16. Each of these parts of the tire

that 10 is preferably made of an elastomeric material such as

  rubber or urethane. The tire 10 is symmetrical relative to the median circumferential plane MP of the tire. This median circumferential plane MP is a plane perpendicular to the axis of rotation of the tire and located

  midway between the two axially outer ends

tire res.

  The width of the tread is defined by the axially outer ends of a tire which

  is supported on the ground in the tire imprint region

  when this tire is inflated to its inflation pressure

  normal deflection and works under its normal load. The empre-

te of a tire refers to the traces left by a tire in contact with the ground when it is mounted in a normal manner on a vehicle under its normal load and when it is inflated to its normal inflation pressure. The normal load and the normal inflation pressure are the load

  and the pressure at which a tire is intended to work

  work in normal conditions.

  Each of the shoulders 14 is oriented axially outward and radially inward from the

  tread 12. Each of the sidewalls 16 extends axially-

  outward and radially outward from

  shot from the corresponding mounting area 18, so that the tire size SD of the tire 10 is at the level

  junction zones 22. The size of the tire flange

  tick is the maximum distance in a section through a radial plane of the tire between the axially extreme surfaces

  tire, excluding inscriptions or signs, me-

  measured on a line parallel to the axis of rotation of the tire-

matic. The junction zones 22 therefore constitute the par-

axially extreme ties of tire 10 when this tire

matic is in its normal conditions of inflation pressure = flage and load. As can be seen in Figs. 1 and 3, the length of the shoulders 14 is approximately equal to that of the flanks 16, although the lengths of the shoulders and

  sides may vary depending on certain considerations

  tions relating to the configuration0 Furthermore, the section height (sh) of each sidewall 16 is preferably infO =

  less than half the height of section SH of the tire

  that 10o In this memo, including in the claims

  cations, the section height SH of the tire is understood

10 the distance measured along a perpendicular line.

to the rotation axis between the internal bearing surfaces

radially extremes of the mounting zones and the external point

  radially constricted from the outer surface of the

  bearing 12 when the tire is under its pressure of -

normal inflation and not under load The radially extreme external point of a sidewall is defined by the radially extreme internal point Y of the cables of the tire reinforcement plies. The section height (sh) of each

  flank is the distance measured along a perpendicular line

cular to the axis of rotation in a radial plane of the tire

only between the radially extreme internal bearing surface of the mounting areas and the radially extreme external point

flank.

The sides 16 are preferably made of an elastic material.

  high-modulus and, as shown in Figs. 1 and 3, they have a concave external surface 27 and a convex internal surface 29. A tire 10 having this type of sidewall configuration is well known in the art and can be designated as "tire with sidewalls subjected to compression". The sidewalls 16 have a significantly thicker wall than those usually found in conventional tires. The shoulders 14 have a relatively thin wall and the wall thickness of the shoulders

is less than that of the flanks 16.

  The tire 10 also comprises a ply reinforcement structure which extends between the zones of

  junction 22. This structure 30 comprises a layer or nap-

  eg 32 of reinforcing cables. The sheet 32 extends from pre-

  ference between the junction zones 22 and it is folded in each junction zone around a stiffening means or heel 35 so as to be superimposed on itself to form

  a radially inner layer 32a and a radial layer-

outer 32b. In this embodiment, the ta-

lon 35 has a modulus of elasticity of at least 100 kg / cm at 10% elongation, its mechanical resistance being greater than

that of the surrounding elastomeric material. Heel 35

tends circumferentially over the entire tire and is preferably made of an elastomeric material or

rubbery, without its nature being limited to these materials.

  For example, heel 35 could be made of a thin material

breuse. The folded part of the radially inner ply 32 which surrounds the bead 35 extends in a closed loop along the circumference of the tire 10 to form a practically rigid hoop 36 which serves to transmit the forces

  from the structure of the reinforcement ply 30 and rete-

  the sides 16 between the rim 20 and the junction zones 22. The hoop 36 is preferably curved and has a concave internal surface 41 and a convex external surface 43,

as shown in Fig. 1.

As can be seen in Figs. 1 and 3, a protec-

inextensible annular tor 44 of reinforcement of the tread is located radially inside the tread 12. As shown in FIG. 4, this protector

44 includes two layers 45 and 46 made up of parallel cables

the lines oriented by forming acute angles with the circular plane

tire MP 10 midpoint, the angle of a

che being in the opposite direction to the angle of the other layer. The protector 44 extends circumferentially over the entire tire 10 to reinforce the tread 12 and may be of any construction and be made of any desired material compatible with the rules of the art. The

axial width of the radially outer layer 45 of the pro-

  guardian is preferably approximately equal to the axial width

the of the tread 12 and larger than the width

axial of the radially inner layer 46 of this protection

  so that the radially outer layer covers

  the radially inner layer of the protector.

The radially outer layer or ply 32 extends from the hoop 36, in the thickness of the shoulder

14 and preferably up to a point located radially in the interior

  tread 12, in the adjacent region

  te at the axially outer edge of the radially in-

  46 of the protector, and axially inside the axially outer edge of the radially outer layer

  45 of the protector. In cases where the ply 32 extends axially-

  ment over the entire width at the apex 47 of the tire 10, radially inside the tread 12, as in the present embodiment, the protector 44 can be omitted. If a protector 44 is provided, the ply 32 can extending axially inward from each shoulder 14 only to a point which covers a corresponding edge 48 of the annular protector. In this case, each shoulder region of the tire 10 is reinforced.

by separate layers of reinforcing cords.

  In the preferred embodiment of the invention,

the angle (a) of inclination of the cables of the ply 32 relative to

  wearing at the median circumferential plane MP of the tire 10 is

  of 45 but this angle can be between 35 and 55 0 The year-

  gle (a) of the cords of the radially inner layer 32a of the ply 32 is the opposite of the angle (b) of the cords of the radially outer layer 32b of the ply 32. These cords

  of the ply 32 serve mainly to reinforce the pneuma-

tick 10 against shear stresses.

Reinforcement means such as ribs 49 provided on the shoulders 14 support these shoulders

so as to keep them out of contact with the ground when

that the tire 10 is deflated and that it is under normal load. The ribs 49 may comprise massive pieces of rigid rubber, or equivalent elements, but they preferably comprise a series of ribs, as shown in FIG. 2, which are located in circumferentially spaced arrangements on the tire 10, also

  both on external surfaces 40 and on external surfaces

nes 51 of the shoulders 14. The ribs 49 of the surface

dull 50 preferably extend from the rush zone

tion 22, along the internal surface of the tire 10, to positions indicated by the letter X in FIG. 1,

  which are at least axially inside the axial edges-

  outer E of the tread 12. Each of the positions X is preferably located in such a way that the

  distance D separating the position X from the circumferential plane me-

dian MP is not less than the distance T between the positions X and the axially outer edges E of the

  tread 12. The positions X are preferably if-

  killed so that the distance D is approximately

  scab at distance T. If position X is placed closer to the median circumferential plane MP, increasing the length of the ribs 49 would lead to an increase in weight without

appreciable additional advantage.

  The ribs 49 formed on the external surface 51 of

  shoulders 14 are placed at spaced circumferential points

essentially on the tire 10 and extend from the junction zones 22 to the outer edges E of the

tread.

The ribs 49 may be made of an elastomeric material such as rubber which has suitable properties for reinforcing the shoulders 14, as has been described in the present specification. As an example of a suitable material, there may be mentioned an elastomeric rubber-based mixture having a shore A hardness of between 70 and 85, a static elastic modulus greater than 45 kg / cm 2 a

low hysteresis value and low deformation value

permanent compression of around 10% when

  the undergoes 25% compression in a 24 hour test.

The ribs 49 are preferably molded onto the corresponding surfaces of the tire 10 during hardening = curing or vulcanization, but they can optionally be formed2 in accordance with good engineering practice, by any process and bonded to the corresponding surfaces of the tire. anyway appropriate, either beforeP

either after the vulcanization of the tire 10.

As seen in Fig0 2, the ribs 49 are spaced such that a series of grooves 52 alternate

with the ribs 49 so as to give a general appearance on-

on the surfaces of the tire. Each of the ribs 49 is preferably situated in a radial plane of the tire, but the angle that each rib forms with the radial plane passing through this rib can vary by a value which can

reach 100 each way.

As shown in Fig. 2, the form of pro-

  preferred wire for ribs 49 is sinusoidal, but other profiles such as a tooth profile can be used

triangular or square.

A function of the ribs 49 is to strengthen or stiffen the shoulders 14 by strengthening the tire 10 in the regions of the shoulders in the radial direction, that is to say in a direction approximately perpendicular

  on the road surface on which the tire 10 cir-

  to avoid the shoulders 14 being in contact

tact with the ground while the deflated tire traverses its footprint area. Each of the ribs 49 is arranged with

so as to most effectively

  this with the minimum quantity of material. In this way, thanks to

this at the geometric arrangement of the ribs 49, the optimum resistance is obtained with the minimum increase in weight. To further improve the quality of building

  ribs 49 in the radial direction, the ribs and groove

  res 52 are spaced the same way inside and outside the shoulders 14 so that each rib

or groove located on one of the two surfaces is coincident

  dence with that located on the other surface. This mode of space

cement also avoids the undulation of the cables of the structure

  reinforcement 30 which would otherwise tend to

occur during vulcanization operation.

The expression "space in the same way" is understood to mean an arrangement in which the ribs 49 and the grooves 52 provided on the surfaces 50 and 51 of the shoulders 14 are

placed each opposite the other. This gives alternati-

in the tire 10, in line with the shoulder 14, a minimum thickness (e) as shown in FIG. 2, which is equal to the thickness of the shoulder without any rib formed on the latter, and a thickness maximum (t) which is equal to the thickness of the shoulder plus the maximum thickness of the rib 49 situated on the internal surface 50 and plus the maximum thickness of a rib 49 situated on the surface

external 51.

The range of values for the maximum thickness (t) on the shoulder 14 depends on the load and the dimensions of the tire. The ratio of minimum thickness to thickness

maximum (e / t) is preferably between 0.3 and 0.7.

* In the present specification, the term "thickness" is used

  a measurement taken in a radial plane along a per-

  pendulum to the structure to be measured.

  The width (w) of one of the ribs 49 is the distance

this between a point of a groove 52 and the corresponding point

laying in the adjacent throat. The total width of a number N of ribs 49 arranged side by side is equal to the product wN. The 2w / t-e ratio is preferably between 095 and 5. As can be seen by referring again to

Fig. 1 and 3, in the preferred embodiment of lein-

vention, three continuous reinforcing elements in the di-

  crenferential rection, for example circumferential ribs

53 are formed on the internal surface of each

one of the junction zones 22 for. strengthen these.

  Each of the ribs 53 extends continuously, in the circumfúrential direction, on the tire 10, to create

a hoop in this pneumatico The ribs 53 are spaced

  created to form a wavy surface and they are

made of an elastomeric material having mechanical strength

sufficient to limit lateral inflation in a direction oriented axially towards the outside of the tire

while the tire is deflated.

  The ribs 53 also help contain the

side walls 16 between the junction zones 22 and the jan-

  te 20 when the tire 10 is deflated The circumferential ribs 53 can be molded on the surface of the tire.

pneumatic 10 during vulcanization0 However, they can

  They are also formed by any process and collect

lées on the surface of the junction zones 22 in any way compatible with the rules of leart, either before or after the vulcanization of the tire 10o During the operation of the tire 10 in the deflated state, the sidewalls 16 flex so that the cross-sectional shape of the tire takes almost the appearance shown in FIG. 3. The sidewalls 16 can be made of an elastomeric mixture having a modulus of elasticity not less than a

kg / cm, measured at 10% elongationo The sides 16 have been

  also a combination of stiffness characteristics at the

bending, curvature and thickness, which is determined con-

  formally to correct engineering work, so that

  retain the sidewalls between the rim 20 and the ring parts

tion 22 in all tire rolling conditions

tick 10.

  Cut filaments, or equivalent elements, may

may be provided in the radial ribs 49 and the nerves

circumferential lines 53. Bars arranged circumferentially

essentially (not shown) can also be pre-

  views between the ribs 49 to establish trans-

  sideways improving mechanical resistance. A lubricant

suitable 54 can be inserted into the tire cavity

that to reduce the abrasion between the internal surfaces of the tire 10 and ensure the cooling of the tire

  during operation in the deflated state.

Since it is not necessary for the mounting areas 18 to have bead links like those used in conventional tires, the

  rim 20 on which the tire 10 is mounted is made

trout in such a way as to almost completely surround the mounting areas, as shown in the drawings, and

  constitute means capable of retaining areas of my-

on the rim when using the tire at

the deflated state.

  As shown in Fig.l, the rim 20 includes a central ring 56 and two outer rings 58 and 60. The central ring 56 and one of the outer rings

  58 or 60, almost completely envelop the area of my

  corresponding stage 18, on the radially integrated surfaces

  superior, axially interior and axially exterior of this zone. Mounting surfaces 62 and 64 are provided on the central ring 56 to apply the mounting areas 18 A seal against the rim 20 so as to close off the

  tire cavity tightly.

  At least three self-locking retaining latches 66 on the circumference of the rim 20 hold the rim

  assemble and retain the outer rings 58 and 60 con-

be the lateral forces, that is to say against the forces which act on these rings in the axial direction. A security screw (not shown) or other similar fixing element can be added to guarantee the locking of

the rim.

Claims (8)

CLAIMS -R E V F, N D I C A T I O N S   1 - A tire capable of rolling in the inflated and deflated state, characterized in that it comprises an annular body of elastomeric material, a tread (12) intended to come into contact with the ground, s' extending circumferentially and situated at the outer periphery of the body, two shoulders (14) which are joined to the strip of bearing and extend axially outward and radiate   inwardly from the tread (12) to two joining areas (22), two sidewalls (16) which extend radially and axially inwardly   from the junction areas (22) to two mounting areas spaced tage (18) provided for mounting the tire on a rim (20), a reinforcement structure (30) comprising   lay of one or more plies, continuous in the circumferential direction, which extends between the junction zones (22); a series of circumferentially spaced reinforcing ribs (49) provided on at least one surface (50 or 51) of each of the shoulders (14), these ribs (49) extending from the junction zones (22) to the tread (12).   2 - A tire according to claim 1, character-   laughed in that each of the sides (16) has a shape   curved to resist external expansion.   3 - Tire according to one of claims 1   and 2, characterized in that ribs (49) extend along the external surface (51) of each of the shoulders (14) between the corresponding junction zone (22) and the   tread (12) and in that the ribs (49) are   also tend along the inner surface (50) of each one of the shoulders (14) between the junction zone (22) and the tread (12), the width (w) of the ribs (49) provided on the internal surface (50) of the shoulder (14)   gradually very equal to the width (w) of the ribs (49) pre-   seen on the external surface (51) of this shoulder, the nerves vures (49) being spaced from each other on the sur- opposite faces (50, 51) of the shoulder (14) in such a way   re that the thickness (t) of the tire in the shoulder (14) is approximately equal to the thickness of the shoulder (14) plus the maximum thickness of a rib (49) provided on the external surface (51 ) of the shoulder (14) and over the maximum thickness = mum of a rib (49) provided on the internal surface (50) of this shoulder, while the minimum thickness (e) of the tire in the region of the shoulder is roughly e   scab has the thickness of the shoulder devoid of rib (49).   4 Tire according to one of claims 1 to 3, characterized in that it further comprises at least one reinforcing rib (53), continuous in the direction confirir ciir, provided on the external surface of each of the junction zones (22), this reinforcing rib (53)   extending over the entire tire. - Tire according to one of claims i a 4, characterized in that each of the ribs (49) is dis-   placed practically in a radial plane of the tire.   6 Tire capable of operating in the inflated state   swollen and in deflated state, characterized in that it comprises a   annular body of elastomeric material, a rolling strip   ment (12) intended to come into contact with the ground, extends   circumferentially and located at the periphery of the body, two shoulders (14) which are joined to the roll band = ment (12) and extend axially outwards and radiate inwardly from the tread (12) to two joining areas (22), two sidewalls (16) which extend radially and axially inwardly   from the junction areas (22) to two mounting areas   spaced tage (18) provided for mounting the tire on a rim (20), a reinforcement structure (30), continuous in the circumferential direction, composed of one or more plies, which extends between the junction zones (22), and at least one reinforcing rib (53), continuous in the circumferential direction, provided on the external surface ( 51) of each of the junction zones (22), this rib (53) extending over the entire tire. 7 - A tire according to claim 6, character- laughed in that each of the sides (16) has a shape curved to resist outward expansion.   8 - A tire capable of working in the inflated and deflated state, characterized in that it comprises a annular body of elastomeric material, a rolling strip   ment (12) intended to come into contact with the circumferentially extending ground and situated at the periphery of this body,   two shoulders (14) which are joined to the tread- ment (12) and extend axially outwards and radiate   inwardly from the tread (12) to two joining areas (22), two sides (16) which extend radially and axially inward from the joining areas (22) up to two spaced mounting areas (18) provided for mounting the tire   on a rim (20), a reinforcement structure (30),   continuous in the circumferential direction, formed of one or   of several layers, and which extends between the areas of rush tion (22), this reinforcing structure (30) comprising at at least two superimposed layers (32a, 32b) of reinforcement cords   forcing which extend from the tread (12) to the junction zones (22), the cables of one of the superposed layers being inclined in the opposite direction to that of the cables of the other of the layers superimposed, the cables of these superimposed layers (32a, 32b) being inclined at an angle of 35 to 55 relative to the circumferential plane median (MP) of the tire. 9 - A tire according to claim 8, character- laughed in that the superimposed layers (32a, 32b) of the structure   reinforcing structure (30) are folded up to form a cargo te having a radially inner surface (41) of concave shape and a radially outer surface (43) of convex shape, the tire further comprising in each of the junction zones (22) a bead (35) around which the superimposed layers (32a , 32b) are folded back to form the hoop (36) and the heel (35) having a modulus of elasticity   at least 100 kg / cm2 at 10% elongation. - Tire according to one of the claims 8 and 9, characterized in that each of the sides (16) has a   curved profile to resist external radial expansion better.   11 - Tire according to one of claims   8 to 10, characterized in that it further comprises at least one reinforcing rib (53), continuous in the direction   circumferential, on the outer surface of each of the zo-   nes of junction (22), this reinforcing rib (53) extends stretching over the entire tire.   12 - Tire according to one of claims   8 to 11, characterized in that it further comprises a series circumferentially spaced reinforcing ribs (49)   ment on at least one surface (50 or 51) of each of the shoulders   elements (14), these ribs extending from the corresponding junction zone (22) up to the tread (12), each of the ribs (49) being arranged so as to form an angle from 0 to 10 with a radial plane passing through the rib, and in that the ribs (49) spaced circumferentially ferentially extend as well along the surface   internal (50) than the external surface (51) of each of the   shoulders (14), between the corresponding junction area (22)   dante and the tread (12), the width (w) of the nerves   vures (49) provided on the internal surface (50) of this shoulder   element (14) being approximately equal to the width (w) of the nerves   vures (49) provided on the external surface (51) of this shoulder ment, the ribs (49) being spaced from each other on the opposite surfaces (50, 51) of each shoulder (14) so that the maximum thickness (t) of the tire in the shoulder (14) is little almost equal to the thickness (e) of this shoulder plus the maximum thickness of the rib (49) provided on the external surface (51) of the shoulder and plus the maximum thickness of the rib (49) provided on the   internal surface (50) of this shoulder and in that the thick   minimum tire tire in the shoulder is approximately   equal to the thickness (e) of this shoulder without rib.