Tyre with simplified carcass reinforcement

Abstract

The invention relates to a tyre for a motor vehicle, said tyre being designed as a standardized manufacturing with a carcass reinforcement comprising two layers. The first layer (41) is anchored in two beads (50) by a bead (53) surrounding a bead wire (51), thereby forming a main portion (52) and a bead (53) in each bead. A second layer (42) is laid axially and radially outside the first carcass layer and axially inside the bead of the bead of the first carcass layer. The length HNC1 of the bead (53) of the first carcass layer (41) is comprised between 10% and 30% of the height of one sidewall (30); length LREC is included in [0.6 * HNC1; 0.9 * HNC1], and the maximum value of the distance (LNDEG, LNDED) is included in the range of [2; 18] mm.

Description

Technical Field

[0001] The present invention relates to a motor vehicle tyre designed for standardized production of its carcass reinforcement comprising two carcass plies.

[0002] definition

[0003] By convention, consider a reference system (O, OX, OY, OZ) whose center O coincides with the center of the tire; the circumferential direction OX, the axial direction OY and the radial direction OZ respectively represent the direction tangential to the tread surface of the tire in the direction of rotation, the direction parallel to the axis of rotation of the tire, and the direction perpendicular to the axis of rotation of the tire.

[0004] Radially inwards and radially outwards mean respectively closer to and further away from the axis of rotation of the tire.

[0005] Axially inward and axially outward mean respectively closer to and further away from the equatorial plane of the tire, the equatorial plane of the tire being a plane passing through the middle of the tire tread and perpendicular to the axis of rotation of the tire.

[0006] The composition of a radial tire is usually described by the representation of its constituent components in a meridian plane, i.e. a plane that includes the tire's axis of rotation. This choice is motivated by the axial symmetry of the tire's geometry around its axis of rotation. The tire also includes a plane of symmetry perpendicular to the axis of rotation and passing through the center of the tread: it is the equatorial plane.

[0007] A radial tire is intended to come into contact with the ground via a tread whose two axial ends are connected, by two sidewalls, to two beads providing the mechanical connection between the tire and the rim on which it is intended to be mounted.

[0008] The radial tire also comprises a reinforcement consisting of a crown reinforcement radially on the inside of the tread and a carcass reinforcement radially on the inside of the crown reinforcement.

[0009] The crown reinforcement of a radial tire comprises a superposition of circumferentially extending crown layers radially outside the carcass reinforcement. Each crown layer is made up of reinforcements parallel to one another and coated with a polymer material of the elastomeric type or of the elastomeric compound type. The assembly consisting of the crown reinforcement and the tread is called the crown.

[0010] The carcass reinforcement of a radial tire generally comprises at least one carcass layer, which is composed of metal reinforcing elements or textile reinforcing elements coated with an elastomeric coating compound. The reinforcing elements are substantially parallel to each other and form an angle between 85° and 95° with the circumferential direction. The carcass layer comprises a main portion, which connects the two beads together and is wound around an annular reinforcing structure (which is most commonly a bead wire for forming a bead hoop) in each bead.

[0011] Each bead is thus located radially innermost, so as to be in contact with the rim, and comprises at least in part the following components:

[0012] 1. At least a portion of the airtight layer covering the inner cavity of the tire;

[0013] 2. a carcass reinforcement comprising at least a first carcass layer axially and radially outside the first airtight layer;

[0014] 3. a bead filling layer filling the volume defined by the turned-up hoop of the first carcass layer of the carcass reinforcement around the bead wire;

[0015] 4. The bead wire formed by the assembly of cords;

[0016] 5. A reinforcing filling layer of the bead located axially outside the turnup of the first carcass layer;

[0017] 6. the axially innermost protective layer which partially constitutes the outer circumference of the tire and is intended to come into contact with the rim;

[0018] 7. The connecting layer between the carcass reinforcement and the crown of the tire;

[0019] 8. The axially outermost sidewall layer that constitutes the outer wall of the tire in contact with the surrounding environment.

[0020] For large sizes, with rim diameters greater than 16 inches, most usually the carcass reinforcement comprises, in addition to the first carcass layer turned up around the bead wires, a second carcass layer. Depending on the position of this second carcass layer, type A beads and type B beads are distinguished.

[0021] For type A bead, the second carcass layer is laid axially and radially on the outside of the first carcass layer. In this bead, the second carcass layer is axially located on the outside of the turnup of the first carcass layer.

[0022] For type B beads, the second carcass layer is also laid axially and radially outside the first carcass layer, but the second carcass layer is axially inside the turnup of the first carcass layer and is in contact with a major part of the first carcass layer before it is turned up around the bead wire.

[0023] The radial tire (more specifically the unvulcanized annular green tire) as shown above is usually manufactured by a method with two distinct stages. In the first stage, a cylindrical blank of the carcass reinforcement is manufactured on a cylindrical tire building drum, the blank comprising in particular the carcass reinforcement itself, the elastomeric compound and the reinforcement inside the reinforcement, and all the elements constituting the beads (i.e. bead wires, bead filling layers and profiled elements, and bead reinforcement).

[0024] The portion of the blank radially below the bead wire is then expanded radially until it is locked below the bead wire. The portion between the bead grooves is then deformed radially to obtain an annular shape while the grooves are moved axially closer together. The tightening below the bead wire should be sufficient to prevent any relative movement relative to the bead wire during this operation. This operation, during which the bead is first formed and then the sidewall of the tire is formed, is called "ply turnover".

[0025] In a second stage, the cylindrical blank of the carcass reinforcement is shaped and then expanded to an annular shape on which are then laid the elements constituting the crown reinforcement, the rubber layers and shaped elements separating said crown reinforcement from the carcass reinforcement, and the tread.

[0026] The annular and unvulcanized green tire is then introduced into a vulcanization mold, said green tire undergoing slight additional shaping to provide the final dimensions of the tire.

[0027] Upstream of the first manufacturing step is the preparation of the individual parts, that is to say the semi-finished product, which is a shaped element of the elastomeric compound obtained by an extruder arranged at the outlet and having suitable tools for producing parts of the elastomeric compound suitable for making each of the parts of the tire. Still during this manufacturing stage, the fabric layer is cut to a width resulting from the geometry of the tire, based on the design.

[0028] With the help of technological progress, tire building machines are increasingly automated. The above steps are introduced into an automatic tire building machine, which includes a building drum moving in front of a workbench for winding the semi-finished product in steps corresponding to the laying of the above products 1 to 8.

[0029] Automatic tire building machines are configured for either type A beads or type B beads. Today, it is difficult to continuously manufacture a first bead of type A and then a second bead of type B (or vice versa) on these machines without making adjustments that adversely affect industrial performance.

[0030] Such adaptations include, for example, modifying an automatic tire building machine by adding an additional manufacturing station to provide flexibility so that both types of beads can be manufactured. Background Art

[0031] Document FR 2 900 097 A1 mentions type A beads and type B beads in the context of designing an extended mobility tire with self-supporting sidewalls. However, this design requires an adjustment from one type to another during the manufacturing process.

[0032] With regard to document EP0595653A1, a bead of type A is proposed, but with a reinforcement layer coated with an additional elastomeric compound relative to conventional solutions. This solution has the disadvantage of increasing the industrial production costs of the tire.

[0033] Documents DE102015207714A1 and WO02 / 096676A1 disclose tire structures involving carcass reinforcements having at least two carcass layers for improving the performance of the tire. Documents US6273164B1 and US2019 / 001758A1 relate to motorcycle tires having carcass reinforcements also comprising two layers.

[0034] The aim that the inventors have set themselves is to devise a structure of a tire bead which advantageously replaces type A and type B beads without adversely affecting the technical and industrial properties. Summary of the invention

[0035] This object has been achieved by the design of a passenger vehicle tyre comprising, in the meridian plane, the following parts:

[0036] two beads, two sidewall layers, and a crown, the beads being intended to be mounted on a rim, the sidewall layers being connected to the beads, the crown having a tread intended to come into contact with the ground, the crown having a first side connected to the radially outer end of one of the two sidewall layers and a second side connected to the radially outer end of the other of the two sidewall layers;

[0037] a carcass reinforcement comprising two carcass plies extending from the two beads through the sidewalls as far as the crown and each comprising a plurality of carcass reinforcing elements;

[0038] a first carcass layer anchored in both beads by turning up around reinforcing bead wires, thereby forming a main portion and a turn up in each bead;

[0039] a bead filling layer of an elastomeric compound, said bead filling layer occupying a volume defined by the radially outer contour of at least part of said main portion, of the turn-up and of the bead wire;

[0040] In the first bead and the second bead (50), the radial distance (LNDEG, LNDED) is defined as the radial inner distance of the first end and the second end of the second carcass layer (42) from the axial straight line B1 tangent to the bead line at the radially outermost point;

[0041] The second carcass layer is laid axially and radially on the outside of the first carcass layer, is axially located on the inner side of the turned-up edge of the first carcass layer in the bead, and is axially located on the outer side of the bead filling layer, so that the second carcass layer is in contact with the turned-up edge of the first carcass layer over the length LREC;

[0042] In each bead, the length HNC1 of the curl of the first carcass layer ranges from 10% to 30% of the height of one sidewall of the tire, and the length HNC1 is measured from a first radially innermost point of the bead line to a second radially outermost point of the curl constituting the first carcass layer; the length LREC is included in the range of [0.6*HNC1; 0.9*HNC1], and the maximum value of the distance (LNDEG, LNDED) is included in the range of [2; 18] mm.

[0043] The tire of the present invention differs from the prior art in that the structure of the bead comprises a second carcass layer, which is axially and radially located on the outside of the first carcass layer. In the bead, the second carcass layer is axially located on the inside of the turn-up of the first carcass layer and axially located on the outside of the bead filling layer. The relative position of the ends of the product in the bead is such that the technical performance of the product is ensured and the industrial performance is maintained compared to the manufacture of conventional solutions. The bead of the present invention advantageously replaces the type A bead or the type B bead without adversely affecting the industrial or technical performance.

[0044] The bead of the tire of the invention comprises a stack of layers of reinforcement coated with an elastomeric compound: the main part of a first carcass layer, a turn-up and a part of a second carcass layer. The material properties of the elastomeric compound of the bead, the thickness of the layers and the overlap length are defined to optimize the operation of the bead.

[0045] According to the present invention, the length of the bead of the first carcass layer ranges between 10% and 30% of the height of the tire sidewall. This sidewall height is standardized for each tire size and can be obtained, for example, in the standard manual of ETRTO (European Tire and Rim Technical Organization). Its value can also be evaluated based on the standardized name of the tire. The inventors set the length of the bead HNC1 based on the height of the sidewall to extend the operation of the present invention to all passenger vehicle tire sizes. When HNC1 is equal to about 10% of the sidewall height, the unwinding of the reinforcement of the first carcass layer below the bead line is avoided. Specifically, if the length of the bead is insufficient (i.e., less than 10% of the sidewall height), the tension in the first carcass layer will cause the reinforcement to retract, and the tire may be irreversibly damaged. According to the inventors, HNC1 should be less than 30% of the sidewall height so that the maximum bending area occurs when the tire rotates and is compressed by the load carried.

[0046] Within the context of the present invention, a mechanical coupling state is defined in a stack of composite layers having at least two layers, each layer comprising a reinforcement coated with an elastomeric compound, for a pneumatic tire mounted on a rim, by subjecting it to an inflation pressure of 250 kPa. Under these stress conditions, the mechanical coupling state is obtained when the shear stress of the elastomeric compound located between the reinforcements is constant in the axial and radial directions over the entire length of the stack. Under these conditions, the tensile stiffness of the reinforcements reaches a maximum and the stack of composite layers contributes to the full potential of its operation on the bead.

[0047] A first condition for achieving mechanical coupling in the stack of bead compounds is that the radial distance between the centers of two adjacent reinforcements of the first and second layers of the stack is less than 1.5 times the diameter of the reinforcements of said layers. A second condition is a sufficient overlap length between the turn-up of the first carcass layer and the radially inner portion of the second carcass layer. According to the inventors, in the case of passenger vehicle tires, an overlap length LREC comprised in the range [0.6*HNC1; 0.9*HNC1] is sufficient.

[0048] The standard of the mechanical connection of the stacked layers is expressed as a function of the diameter of the reinforcement of the layer. In order to determine the diameter of the fabric reinforcement, a device is used, which can measure the shadow of the reinforcement irradiated by a parallel laser beam with an accuracy of 0.1 micron through a receiver consisting of a collection optical system, a photodiode and an amplifier. This device is sold, for example, by Z-Mike with the reference number "1210". The method includes fixing the reinforcement sample whose diameter is to be measured on a powered moving workbench under a standard pretension of 0.5 centinewtons / tex (cN / tex) after the reinforcement has been subjected to preliminary adjustment. When fixed on the moving workbench, the reinforcement moves perpendicular to the projection shadow measurement system at a speed of 25mm / s and cuts the laser beam perpendicularly. At least 200 projection shadow measurements are performed on a 420mm long cord; the average value of these projection shadow measurements represents the diameter of the reinforcement.

[0049] In order to make industrial manufacturing easier, the inventors propose that the maximum value of the distance (LNDEG, LNDED) (which represents the maximum distance from the radially innermost end of the second carcass layer to the axial straight line B1 tangent to the bead line at the radially outermost point) is included in the range of [2; 18] mm.

[0050] Still for industrial optimization purposes, advantageously, in each bead, the axial thickness EBT of the bead filling layer measured from the radially innermost end of the second carcass layer to the main part of the first carcass layer is included in the range of [EBTmin; EBTmax], where EBTmin is equal to 0.5 times the outer diameter of the bead wire and EBTmax is equal to 1.2 times the outer diameter of the same bead wire.

[0051] The combination of the main characteristics of the invention results in a tyre of the invention which can advantageously replace type A beads or type B beads in manufacture, while still ensuring the same performance levels.

[0052] In addition to the main features of the invention, the inventors have also identified methods related to the geometry of the product and its material properties in order to even better optimize the compromise between technical and industrial performance.

[0053] The distance (LNDEG, LNDED) is an example of a dimension of the tire structure that enables the carcass ply length to be adjusted. Advantageously, the distance (LNDEG, LNDED) is the same in each of the two beads.

[0054] Having the same distances (LNDEG, LNDED) on either side of the equatorial plane centres the carcass reinforcement relative to the axis (OZ), the effect of which is to contribute to the uniformity of the tyre while avoiding imbalances due to a distribution of masses and forces not conforming to the symmetry of the tyre.

[0055] According to one embodiment of the invention, the second carcass layer is discontinuous. After the tire is inflated and mounted on the rim, the second carcass layer can be compressed in the area located in the center of the tread. According to the inventors, a portion of the second carcass layer in this compressed area can be eliminated. Under these conditions, the second carcass layer takes the form of two parts, which are located on both sides of the equatorial plane and extend from the bead to the shoulder of the tire.

[0056] There are other constructions where the second carcass layer is discontinuous when, for example, it is comprised of continuous carcass layer portions.

[0057] Preferably, each carcass layer has a distributed breaking tension greater than or equal to 11 daN / mm, the distributed breaking tension being the product of the breaking force of the reinforcement of the layer and the spacing between the layers.

[0058] The distributed tension of a layer is the product of the stress in the direction of the reinforcement and the thickness of said carcass layer. According to the inventors, the dimensions of each carcass layer should be large enough to have a distributed tension value of at least 11 daN / mm. The length of the second carcass layer can be reduced according to the values ​​assigned to LREC, (LNDEG, LNDED) and HNC1, but the carcass reinforcement as a whole should maintain sufficient tensile strength in the direction of the reinforcement.

[0059] Preferably, the first carcass layer and the second carcass layer are made of the same material. The motivation for this embodiment is to achieve standardization by using the same material for both carcass layers and thus reduce material costs. To enhance this standardization, not only the materials are the same, but also the characteristics and components of the reinforcements, the density of the reinforcements in each layer and the elastomeric compound used for coating are the same.

[0060] Preferably, the reinforcement of the carcass layer is a textile cord, each cord being obtained by twisting N strands of textile material with a twist T2 in a given direction D1 (S direction or Z direction, respectively), wherein N ≥ 1, and each strand being produced by over-twisting the spun yarn of the textile material with a twist T1 in an opposite direction D2 (Z or S direction, respectively).

[0061] Preferably, the spun yarn is made from a mixed assembly of filaments of textile material (eg nylon, PET, aramid).

[0062] Advantageously, the number N of strands for twisting ranges between 2 and 6, preferably N=2.

[0063] Preferably, the overtwisting twist T1 and the twisting twist T2 are the same and less than 500 turns / m, preferably T1 and T2 are the same and less than 440 turns / m, and more preferably T1 and T2 are the same and less than or equal to 315 turns / m.

[0064] According to another embodiment, in each bead, its lateral reinforcing layer is axially outside the turnup of the first carcass layer and is in contact with said turnup on one side and at least partially axially outside with the sidewall layer on the other side.

[0065] According to this particularly advantageous embodiment, the bead filling layer and the lateral reinforcing layers of the bead are made from the same elastomeric compound having a shear modulus of elasticity greater than or equal to 25 MPa, measured under alternating strain at a frequency of 10 Hz and a temperature of 23°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Other details and advantageous features of the invention will become apparent from the following description of exemplary embodiments of the invention given with reference to the accompanying drawings, which show a meridian view of a tire design according to an embodiment. To facilitate understanding, the drawings are not shown to scale.

[0067] Figure 1 Including video Figure 1 -A and video Figure 1 -B, the view Figure 1 -A shows a cross section through a meridian plane of a tire according to the invention, said view Figure 1 -B means meridian view Figure 1 -A is an enlarged view of the portion surrounded by a dotted circle showing a bead of the tire of the present invention.

[0068] Figure 2 -A. Figure 2 -B shows a prior art having a type A bead ( Figure 2 -A) and type B bead ( Figure 2 -B) tires.

[0069] Figure 3 -A and Figure 3 -B shows an embodiment where the first carcass layer and / or the second carcass layer are discontinuous.

[0070] about Figure 4 , which shows the bead of the tire of the present invention with a schematic diagram of the main dimensions of the present invention. DETAILED DESCRIPTION

[0071] The invention is implemented on a passenger vehicle tire of size 245 / 70R16 according to the specifications of the ETRTO (European Tyre and Rim Technical Organization) standard. Such a tire with a load index of 111 can carry a load of 1090 kg, inflated to a pressure of 290 kPa.

[0072] exist Figure 1-A, with the general reference numeral 1 tire comprises a carcass reinforcement 40, the carcass reinforcement 40 is constituted by a first carcass layer 41, the first carcass layer 41 comprises a main portion 52, the main portion 52 connects two beads 50 together, and in each bead 50 is wound around an annular reinforcement structure. The annular reinforcement structure is a bead wire 51, the bead wire 51 comprises a rigid circumferential element, the rigid circumferential element is most usually metal, wrapped in at least one non-restrictive metal, elastomer or fabric material. The carcass layer 41 is wound around the bead wire 51 from the inside of the tire 1 toward the outside, thereby forming a bead 53 including a radially outer end. In each bead 50, the bead 53 anchors the carcass layer 41 to the bead wire 51 of the bead 50.

[0073] The reinforcing elements of each carcass layer (41, 42) are substantially parallel to one another and form an angle of between 85° and 95° with the circumferential direction.

[0074] Each bead 50 comprises a bead filler 55 which continues radially outwardly the bead wire 51. The bead filler 55 is made of at least one elastomeric filling compound. The filling layer axially separates the main part 52 of the carcass reinforcement 41 and the turn-up 53.

[0075] Each bead 50 also comprises a protective layer 54 which continues the sidewall 30 radially inwardly and is axially located outside the turnup 53. The protective layer 54 is also at least partially in contact with the flange of the rim 100 by its axially outer surface. The protective layer 54 is made of at least one protective elastomeric compound.

[0076] The tire 1 also has a crown reinforcement 20, which includes two working layers 21, 22 and a hoop layer 23. Each of the working layers 21 and 22 is reinforced by a filamentary reinforcing element, which is parallel in each layer and crosses from one layer to another, thereby forming an angle between 10° and 70° with the circumferential direction. The hoop layer 23, which is radially located outside the layers (21, 22), is formed by reinforcing elements oriented in the circumferential direction, which are spirally wound on the axial width of the crown. The tread 10 is laid radially on the outside of the hoop layer 23; this tread 10 provides contact between the tire 1 and the ground. The tire 1 depicted is a "tubeless" tire: it includes a "liner" 80, which is made of a rubber composition that is impermeable to the inflation gas and covers the inner surface of the tire.

[0077] Figure 2 -A. Figure 2 -B shows a prior art having a type A bead ( Figure 2 -A) and type B bead ( Figure 2-B). These figures comprise a carcass reinforcement 40 comprising carcass layers (41, 42) and a turn-up 53. The bead filling layer 55 is a layer of elastomeric compound that fills the volume defined by the main part of the first carcass layer 41 and its turn-up 53.

[0078] Figure 3 -A. Figure 3 -B shows an exemplary embodiment of a tire of the invention having a layer of discontinuous carcass reinforcement. Figure 3 -A, the second carcass layer is cut off in a region extending over the center of the crown, while in Figure 3 -B, both carcass layers are interrupted in this same area. In both cases where the carcass layers are discontinuous, the layer 45 of elastomeric compound is replaced by the locally missing carcass layer. The addition of a lateral reinforcing layer 70 may prove necessary to maintain the stiffness of the beads at a sufficient level for the tire to function well.

[0079] Figure 4 The main dimensions of the structure of the tire bead of the present invention are shown. In the bead, the dimension LREC represents the length of the contact area between the bead 53 of the first carcass layer 41 and the radially inner part of the second carcass layer 42. The dimension LREC is involved in the mechanical connection of the stack consisting of the main part 52 of the first carcass layer 41, the bead 53 and the radially inner part of the second carcass layer 42. When a sufficient value is assigned to LREC to establish the mechanical connection, the stack of composite layers forms a rigid block that gives the bead a maximum level of radial and axial stiffness. The thickness of the bead filling layer EBT and its elastic shear modulus are other parameters involved in establishing the mechanical connection of the stack. The length of the bead HNC1 should be sufficient to avoid the unwinding of the first carcass layer below the bead line without being located in the compression zone after the tire is compressed by the load carried. The radial lengths LNDEG and LNDED are related to the development of the tire deconstruction of the present invention. The tire deconstruction consists of returning to uncured individual components based on a theoretical version of vulcanization designed, for example, by computer-aided design, and then stacking them around the tire building and finishing drum. The radial length LNDED is the symmetrical length of LNDEG relative to the axis (OZ) of the second bead of the tire.

[0080] The construction of the tire of the invention was tested in order to clearly highlight the performance provided by the invention. The results of these tests were compared with those obtained on the control tire.

[0081] The first control C1 is a tire of conventional design with type A beads, and the second control tire C2 has type B beads. Each tire (C1, C2) comprises two carcass layers (41, 42) made of the same material: each carcass layer (41, 42) comprises a reinforcement made of polyester, formed by two threads, each having a count of 140 tex, overtwisted and twisted at a tension of 420 turns / m, and coated with an elastomeric compound. The distributed breaking tension in the carcass layer is 22 daN / mm.

[0082] The tire P1 according to the invention is provided with the same carcass layers (41, 42) as the control. The main dimensions of the structure of P1 are as follows:

[0083] [Table 1]

[0084]

[0085] It can be easily verified that the tyre P1 complies with the invention.

[0086] The rolling resistance test is carried out according to standard ISO 28580. For the tyre tested, the result is the rolling resistance coefficient, which expresses the ratio of the resistance exerted by the hysteresis of the tyre to the forward movement of the vehicle divided by the load carried.

[0087] The lateral cornering stiffness is measured on a dedicated measuring machine, such as that sold by MTS.

[0088] The durability test consists of subjecting the tire to cycles of load and pressure stresses when it is compressed onto a rotating wheel. Such a test is described, for example, in UN / ECE (United Nations Economic Commission for Europe) Regulation No. 30, which is required for the technical approval of tires.

[0089] A result greater (or less) than 100% indicates an improvement (or decrease) in the performance criterion considered.

[0090] The results obtained are summarized in Table 2 below:

[0091] [Table 2]:

[0092] Rolling resistance Lateral cornering stiffness Durability C1 100 100 100 C2 100 98 100 P1 100 99 102

[0093] The tire of the invention meets the objective of having the same technical performance level as the reference tires C1 and C2. The level of lateral cornering stiffness is significantly reduced, but its proportion is not perceptible to the user and does not adversely affect the vehicle's behavior.

[0094] The tyre P1 of the invention advantageously replaces tyres having beads of type A and / or beads of type B. This solution improves industrial performance compared to the continuous manufacture of tyres of type A and type B, which requires adjustments to the process.

Claims

1. A tire (1) for a passenger vehicle, the tire (1) comprising: two beads (50) intended to be mounted on a rim (100), two sidewall layers (30) connected to the beads (50), and a crown (20) having a tread (10) intended to come into contact with the ground, the crown (20) having a first side connected to the radially outer end of one of the two sidewall layers (30) and a second side connected to the radially outer end of the other of the two sidewall layers (30); a carcass reinforcement (40) comprising two carcass layers (41, 42) extending from two beads (50) through the sidewall layers (30) as far as the crown (20) and each comprising a plurality of carcass reinforcing elements; A first carcass layer (41) is anchored in the two beads (50) by means of a turn-up (53) around a reinforcing bead wire (51), thereby forming a main part (52) and a turn-up (53) in each bead; a bead filling layer (55) of an elastomeric compound, said bead filling layer (55) occupying a volume defined by the main portion (52), the turn-up (53) and at least part of the radially outer contour of the bead wire (51); In the first bead and the second bead (50), the radial distance (LNDEG, LNDED) is defined as the radial inner distance of the first end and the second end of the second carcass layer (42) from the axial straight line B1 tangent to the bead line at the radially outermost point; The second carcass layer (42) is laid axially and radially on the outside of the first carcass layer (41), is axially located inside the bead of the first carcass layer (41) in the bead (50), and is axially located outside the bead filling layer (55), so that the second carcass layer (42) is in contact with the bead (53) of the first carcass layer (41) over a length LREC; In each bead (50), the length HNC1 of the turnup (53) of the first carcass layer (41) ranges from 10% to 30% of the height of one sidewall (30) of the tire (1), the length HNC1 being measured from a first radially innermost point of the bead line (51) to a second point constituting a radially outermost end of the turnup (53) of the first carcass layer (41), the length LREC being included in the range of [0.6*HNC1; 0.9*HNC1], the maximum distance (LNDEG, LNDED) being The value is included in the range of [2; 18] mm, and the tire (1) is characterized in that, in each bead (50), the axial thickness EBT of the bead filling layer (55) measured from the radially innermost end of the second carcass layer (42) to the main part (52) of the first carcass layer (41) is included in the range of [EBTmin; EBTmax], where EBTmin is equal to 0.3 times the outer diameter of the bead wire (51), and EBTmax is equal to 1.2 times the outer diameter of the same bead wire (51).

2. The tire (1) according to claim 1, wherein: The radial distances (LNDEG, LNDED) are the same in each of the two beads (50).

3. Tyre (1) according to any one of the preceding claims, wherein: The second carcass layer (42) is discontinuous.

4. Tyre (1) according to any one of the preceding claims, wherein: Each carcass layer (41, 42) has a distributed breaking tension greater than or equal to 11 daN / mm, the distributed breaking tension being the product of the breaking force of the reinforcement of the layer and the spacing between the layers.

5. The tire (1) according to claim 4, wherein: The first carcass layer and the second carcass layer (41, 42) are made of the same material.

6. The tyre (1) according to any one of claims 4 and 5, wherein: The reinforcement of the carcass layer (41, 42) is a fabric cord, each cord is obtained by twisting N strands of fabric material in a given direction D1 with a twist T2, where N≥1, and each strand is produced by over-twisting the spun yarn of the fabric material in an opposite direction D2 with a twist T1, the given direction D1 is S direction or Z direction, and the opposite direction D2 is Z or S.

7. Tyre (1) according to the preceding claim, wherein: Spun yarns are made from mixed components of filaments of textile materials such as nylon, PET, aramid.

8. The tyre (1) according to any one of claims 6 and 7, wherein: The number N of strands used for twisting ranges between 2 and 6, preferably N=2.

9. The tyre (1) according to any one of claims 6 to 8, wherein: The overtwisting twist T1 and the twisting twist T2 are the same and less than 500 turns / m, preferably T1 and T2 are the same and less than 440 turns / m, and more preferably T1 and T2 are the same and less than or equal to 315 turns / m.

10. Tyre (1) according to any one of the preceding claims, wherein: In each bead (50), the lateral reinforcing layer (70) is axially outside the turnup (53) of the first carcass layer (41) and is in contact with the turnup (53) on one side and at least partially in contact with the sidewall layer (30) axially outside on the other side.

11. Tyre (1) according to the preceding claim, wherein: The bead filling layer (55) and the lateral reinforcing layer (70) of the bead (50) are made from the same elastomeric compound having an elastic shear modulus greater than or equal to 25 MPa, measured under alternating strain at a frequency of 10 Hz and a temperature of 23°C.

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