Tyre comprising relocated markings

Abstract

The invention relates to a tyre with a radial carcass reinforcement, the profile of the outer surface of which comprises, on its sidewalls, a concave portion such that the centre of a circle inscribed in said concave portion is axially outside the outer surface of the tyre. According to the invention, at least one mandatory marking of the tyre is inscribed in the concave portion.

Description

TIRE WITH DEOCAEISE MARKINGS

[0001] The present invention relates to a tire with a radial carcass reinforcement and more particularly to a tire intended to equip vehicles carrying heavy loads and traveling at sustained speed, such as, for example, trucks, tractors, trailers or road buses.

[0002] In general, in heavy-duty tires, the carcass reinforcement is anchored on both sides in the bead area and is radially surmounted by a crown reinforcement consisting of at least two superimposed layers formed of parallel wires or cables in each layer and crossed from one layer to the next at angles between 10° and 45° with the circumferential direction. These working layers, forming the working reinforcement, may be further covered by at least one protective layer formed of advantageously metallic and extensible reinforcing elements, known as elastic elements.It may also include a layer of low-extensibility wires or cables forming an angle of between 45° and 90° with the circumferential direction. This layer, known as the triangulation layer, is radially positioned between the carcass reinforcement and the first crown layer, known as the working layer, which is formed of parallel wires or cables having angles of no more than 45° in absolute value. The triangulation layer, together with at least the aforementioned working layer, forms a triangulated reinforcement that exhibits minimal deformation under the various stresses it is subjected to. The triangulation layer's essential role is to resist the transverse compression forces exerted on all the reinforcing elements in the crown area of ​​the tire.

[0003] Cables are said to be inextensible when, under a tensile force equal to 10% of the breaking force, said cables exhibit a relative elongation of no more than 0.2%.

[0004] Cables are said to be elastic when, under a tensile force equal to the breaking load, said cables exhibit a relative elongation of at least 3% with a maximum tangent modulus less than 150 GPa.

[0005] Circumferential reinforcement elements are reinforcement elements that make angles with the circumferential direction within the range of +2.5°, -2.5° around 0°.

[0006] The circumferential direction of the tire, or longitudinal direction, is the direction corresponding to the periphery of the tire and defined by the direction of rolling of the tire.

[0007] The transverse or axial direction of the tire is parallel to the axis of rotation of the tire.

[0008] Radial direction is a direction that intersects the axis of rotation of the tire and is perpendicular to it.

[0009] The axis of rotation of the tire is the axis around which it rotates in normal use.

[0010] A radial or meridian plane is a plane that contains the axis of rotation of the tire.

[0011] The circumferential median plane, or equatorial plane, is a plane perpendicular to the axis of rotation of the tire and which divides the tire into two halves.

[0012] It is also known to produce tires with sidewalls that have a recessed section forming a concave part. Such sidewall geometries, described for example in document JP4512210B2, are specifically designed to optimize tire performance in terms of durability.

[0013] Document WO 2020 / 012122 further describes a sidewall geometry with a concave part that allows for better resistance to damage in case of contact with curb edges while maintaining satisfactory endurance properties.

[0014] Heavy-duty tires typically still incorporate one or more layers of reinforcing elements, known as stiffeners, in the bead area. These layers are most often made up of reinforcing elements oriented at an angle of less than 45°, and more commonly less than 25°, relative to the circumferential direction. The primary function of these reinforcing layers is to limit the longitudinal movement of the bead materials relative to the wheel rim, thereby preventing premature bead wear. They also help to limit permanent bead deformation on the rim hook, caused by the dynamic thinning of the elastomeric materials. Excessive bead deformation can prevent tire retreading.They also contribute to protecting the lower areas of the tire from damage sustained during the mounting and dismounting of tires on rims.

[0015] Furthermore, in the case of carcass reinforcement anchoring made around a bead, which consists of wrapping at least part of the carcass reinforcement around a bead in each of the ridges by forming a turn extending more or less high in the sidewall, the layers of reinforcement or stiffening elements still make it possible to avoid or delay the unwinding of the carcass reinforcement during accidental and excessive heating of the rim.

[0016] These layers of reinforcement elements or stiffeners are most often arranged axially outside the reversal of the frame reinforcement and extend over a height in the side greater than that of the reversal in particular to cover the free ends of the reinforcement elements of said reversal.

[0017] Such tire designs are described for example in documents FR 2779387 or US 2006 / 0000199 or GB 2065 573.

[0018] The presence of these layers of reinforcing elements or stiffeners contributes to thickening the bead area down to the bottom of the sidewall area towards the tire area where it has its greatest axial width.

[0019] Tires also feature markings on their sidewalls that allow for tire identification and other information. Some markings are mandatory and required for tire identification. Furthermore, they are essential for tire retreading, as the tire must be perfectly identified.

[0020] During driving, vehicles may rub against curbs or other obstacles. While this friction doesn't always damage the tire, it can lead to the fading and disappearance of the markings. This can render the tire unidentifiable and therefore unusable, and often impossible to retread.

[0021] The inventors have thus set themselves the mission of providing tires for "Heavy Goods Vehicles", whose endurance performance, in particular the endurance of the bead areas, is maintained and whose design reduces the risk of disappearance of the regulatory markings present on the sidewall of the tire when they come into contact with a curb.

[0022] This goal has been achieved according to the invention by a tire comprising a radial carcass reinforcement, consisting of at least one carcass reinforcement layer formed of reinforcing elements, said tire comprising a crown reinforcement, itself radially capped by a tread, said tread being joined to two beads by means of two sidewalls, in a meridian section of said tire, radially internally at point F, defined by the intersection of a straight line of axial orientation, passing through the axially outermost point E of the main part of the carcass reinforcement layer and the outer surface of the tire, the profile of the outer surface S of the tire comprising a concave part such that the center of a circle inscribed in this concave part is axially external to the outer surface S of the tire, at least one regulatory marking of the tire being inscribed in the concave part.

[0023] The meridian section of the tire is defined according to the invention such that the barycenters of the beads form an axially oriented straight line, said barycenters being separated from each other by a distance equal to the nominal rim width J increased by 20 mm and decreased by twice the axially measured distance between a barycenter of a bead and a point on the outer surface of the tire.

[0024] The position of the outermost axial point E of the main part of the carcass reinforcement is determined on a tire mounted and inflated under nominal conditions. This determination can be carried out, for example, using a tomography technique.

[0025] According to a preferred embodiment of the invention, all the regulatory markings of the tire are inscribed in the concave part.

[0026] Tests have shown that tires manufactured according to the invention exhibit less wear on regulatory markings, even under severe friction against curbs. Furthermore, tires according to the invention appear to maintain performance in terms of durability, particularly in terms of the durability of the bead areas, at least as good as that of more conventionally designed tires.

[0027] These results are all the more surprising given that more common designs of this type of tire have a relatively thick bead area extending down the sidewall area towards the area of ​​the tire where it has its greatest axial width, in particular to better absorb the stresses caused by shocks or friction suffered when in contact with curbs.

[0028] The inventors have thus been able to demonstrate that tires made in accordance with the invention and which have a relatively thin bead area in its outermost radial part allow better protection of the markings, the latter being inscribed in the concave part, in case of contact with the curbs, while retaining satisfactory endurance properties.

[0029] Choosing the registration area was not obvious to a professional, as reading markings in a recessed area becomes difficult when the tire is mounted on a rim, depending on the tire's position and the lighting on the concave section. Indeed, such markings are difficult to read when the tire is mounted on a rim and become almost impossible after driving, as the concave section encourages the accumulation of dirt that obscures the markings.

[0030] The inventors have demonstrated the importance of reading the regulatory markings on tires before mounting them on rims to ensure the correct tire is selected for a vehicle, and also after use, particularly when the tire is worn, for example, to consider retreading. Knowing the exact tire model is therefore crucial. After use, the tire according to the invention can be cleaned to allow for perfect readability of the markings, which, according to the invention, have not been damaged, for example, by rubbing against curbs. The choice, which might seem to hinder the ability to correctly read the markings when the tire is mounted, does not, therefore, affect the proper use of the tires, provided they are regulatory markings.

[0031] According to one embodiment of the invention, said at least one layer of carcass reinforcement elements being anchored in each of the ribs by turning around a rod to form a main part of the carcass reinforcement layer extending from one rod to the other and a turning of the carcass reinforcement layer in each of the ribs, the circle inscribed in said concave part has a radius between 50% and 125% of the distance between the center of gravity of the rod and point F.

[0032] Such values ​​for the radius of the circle inscribed in the concave part allow for the inscription of a maximum number of markings which will be protected during the use of the tire.

[0033] According to another embodiment of the invention, said at least one layer of carcass reinforcement elements being anchored in each of the beads by turning around a rod to form a main part of the carcass reinforcement layer extending from one rod to the other and a turning of the carcass reinforcement layer in each of the beads, said turning of the carcass reinforcement being reinforced by at least one layer of reinforcement elements or stiffener, in a meridional section of said tire, any point on the profile of the outer surface S of the tire, between point F and a point A, is at a constant distance T from the main part of the carcass reinforcement layer 2, said distance being measured at any point along a direction normal to the main part of the carcass reinforcement layer 2, point A is radially outside a first circle Cl of radius RI centered on the end of the fold of the carcass reinforcement layer, RI being between 8 and 13 mm, radially inside point A, the outer surface S of the tire extends by an arc of a circle of radius R2 whose center is axially outside the surface S of the tire, and whose radius R2 is between 50% and 125% of the distance between point F and the center of gravity of the bead, the arc of a circle of radius R2 is tangent at its innermost radial end B to an arc of a circle of radius R3 whose center is axially inside the surface S of the tire, and extending the outer surface S of the tire radially inwards to point C, said point C being a point of tangency between the arc of a circle of radius R3 and the circle C2 of radius RI centered on the outermost radial end of the stiffener, said point C being radially internal to the axially outermost point D of circle C2, the radius R3 being between 50% and 125% of the distance between point F and the center of gravity of rod 4.

[0034] The distance T is measured on the meridian section of said tire along the normal to the main part of the carcass reinforcement layer between the outermost axial point of a reinforcement of the carcass reinforcement layer and a point of said surface S.

[0035] For the purposes of this invention, a constant distance T means that the distance T does not vary by more than 0.5 mm. Variations in thickness are then solely due to the thinning phenomena occurring during the manufacturing and curing of the tire.

[0036] The center of gravity of the rod is determined on the meridian section of the tire.

[0037] According to a preferred embodiment of this other variant of the invention, the radius R2 is greater than 1.5 times the radius RI and preferably less than 8 times the radius RL

[0038] Advantageously according to this other embodiment of the invention, the distance T, measured along a direction normal to the main part of the carcass reinforcement layer, is greater than 3 mm and preferably less than 7 mm.

[0039] The tests showed that the tires thus produced according to this other variant of the invention exhibit particularly remarkable performance in terms of wear as well as in terms of endurance, and in particular in terms of the endurance of the bead areas, at least as good as those of tires of more conventional design.

[0040] The inventors believe this result is due to the profile of the tire's outer surface between points F and C, defined above. This profile modifies the area between the sidewall and the bead, increasing the portion of the sidewall with a constant thickness T. According to the inventors, such a profile leads to more uniform tire deformation upon contact with curbs and reduces the risk of abrasion and / or tearing on the tire's outer surface. Indeed, when a tire impacts a curb, the contact area is its outer surface, specifically the area between points F and A as defined above.The constant thickness T of the sidewall seems to allow for more homogeneous deformation and thus a better distribution of the forces experienced in the event of impact or friction on a curb.

[0041] According to an advantageous embodiment of the invention, the radial distance between point F and point A is greater than 70% of the radial distance between point F and the radially outermost point G of the outer surface S of the tire, for which the distance, measured in a direction normal to the main part of the carcass reinforcement layer, between said main part of the carcass reinforcement layer and the surface S is equal to T, said distance between any point, of the outer surface S of the tire, radially included between points F and G and the main part of the carcass reinforcement layer being constant.

[0042] According to this advantageous variant of the invention, the flank profile thus defined appears to confer even better homogeneity of deformation in case of impact and / or friction on a curb.

[0043] According to a preferred embodiment of the invention, the outermost radial end of the stiffener is radially external to the end of the folded-over carcass reinforcement layer. This embodiment prevents the respective ends of the stiffener and the folded-over carcass reinforcement layer from coinciding, as these ends are radially offset. Furthermore, the stiffener fully protects the folded-over carcass reinforcement layer, particularly with regard to contact with the rim hook and the pressure exerted on it when the tire is in motion.

[0044] According to other embodiments, the outermost radial end of the stiffener is radially inner to the end of the reversal of the frame reinforcement layer.

[0045] Regarding the innermost radial end of the stiffener, it can be radially external to the innermost radial point of the rod. In other embodiments, the stiffener can be engaged radially under the rod, and its innermost radial end is then radially internal to the rod. In still other embodiments, the stiffener can be wrapped around the rod, and its innermost radial end is then axially internal to the reinforcement layer of the frame.

[0046] According to an advantageous embodiment of the invention, in any meridian plane, in each bead, the tire comprises a restraint frame surrounding the rod and a volume of rubbery mixture directly in contact with the rod.

[0047] According to one embodiment of the invention, particularly to further improve the tire's durability, the carcass reinforcement is formed of strengthening elements whose structure is deeply penetrated by polymer blends. These elements may, for example, be cables whose construction increases their penetrability to polymer blends. Alternatively, they may be cables into which polymer blends are incorporated during the manufacturing process. In this case, they may be, for example, cables with at least two layers, at least one inner layer being sheathed with a layer made of a non-crosslinkable, crosslinkable, or crosslinked rubber composition, preferably based on at least one diene elastomer.

[0048] Such carcass reinforcement cables, exhibiting higher penetration rates than usual, can allow the tire to distribute deformation even better along its length, avoiding local concentrations that lead to small radii of curvature.

[0049] Indeed, the carcass reinforcement cables, as defined according to the invention, which are subjected to significant bending phenomena during impacts on the sidewalk, can exhibit better resistance to these bending phenomena due to their penetration rate by the rubber mixtures, which induces better homogeneity of deformation between the areas of the cable in extension and compression due to bending.

[0050] According to one embodiment of the invention, the crown reinforcement of the tire is formed of at least two working crown layers of advantageously inextensible reinforcing elements, crossed from one layer to the other making angles with the circumferential direction between 10° and 45°.

[0051] According to other embodiments of the invention, the top reinforcement also includes at least one layer of circumferential reinforcing elements.

[0052] A preferred embodiment of the invention further provides that the top reinforcement is completed radially on the outside by at least one additional layer, called a protective layer, of so-called elastic reinforcing elements, oriented with respect to the circumferential direction with an angle between 10° and 45° and in the same direction as the angle formed by the inextensible elements of the working layer which is radially adjacent to it.

[0053] The protective layer may have an axial width less than the axial width of the narrowest working layer. Said protective layer may also have an axial width greater than the axial width of the narrowest working layer, such that it covers the edges of the narrowest working layer and, in the case of the radially superior layer being the narrowest, such that it is coupled, in the axial extension of the additional reinforcement, with the widest top working layer over an axial width, and is then, axially on the outside, decoupled from said widest working layer by profiles of a thickness of at least 2 mm.The protective layer formed of elastic reinforcing elements can, in the case mentioned above, be on the one hand possibly decoupled from the edges of said lesser working layer by profiles of thickness substantially less than the thickness of the profiles separating the edges of the two working layers, and on the other hand have an axial width less than or greater than the axial width of the wider top layer.

[0054] According to any one of the embodiments of the invention mentioned above, the top reinforcement can be further completed, radially inside between the carcass reinforcement and the radially inner working layer closest to said carcass reinforcement, by a triangulation layer of inextensible metallic steel reinforcing elements making, with the circumferential direction, an angle greater than 60° and in the same direction as that of the angle formed by the reinforcing elements of the layer radially closest to the carcass reinforcement.

[0055] Other advantageous details and features of the invention will become apparent from the description of the examples of embodiments of the invention, particularly with reference to Figures 1 to 3, which represent: Figure 1, a meridian view of a diagram of a tire according to the invention; Figure 2, an enlarged schematic representation of the outer surface of the tire between the bead area and point F, Figure 3, an enlarged schematic representation of the area of ​​a bead on a reference tire.

[0056] The figures are not shown to scale to simplify understanding.

[0057] Figures 1 and 3 represent only a half view of a tire which extends symmetrically with respect to the axis XX' which represents the circumferential median plane, or equatorial plane, of the tire.

[0058] In Figure 1, the tire 1 is of size 275 / 70 R 22.5 XIncity EVZ. Said tire 1 comprises a radial carcass reinforcement 2 anchored in two beads 3. The carcass reinforcement 2 is clamped at the top of the tire by a crown reinforcement 5, itself capped by a tread 6.

[0059] The carcass reinforcement 2, formed of a single layer of metal cables, is wound in each of the ribs 3 around a rod 4 and forms in each of the ribs 3 a reversal 7 of the carcass reinforcement layer having an end 8.

[0060] Axially outside the inversion 7, there is a stiffener 9 whose outermost radial end 10 is radially outside the end 8 of the inversion 7 of the frame reinforcement layer.

[0061] The radially innermost end 11 of the stiffener 9 is radially outer at the radially innermost point of the rod 4.

[0062] Figure 2 schematically illustrates the outer surface S of the tire between point F and the bead area 3 on a meridian section of the tire, defined so that the centroids of the beads 4 form an axially oriented straight line, said centroids being separated from each other by a distance equal to the nominal rim width plus 20 mm and minus twice the axially measured distance between a centroid of a bead 4 and a point on the outer surface of the tire.

[0063] The outermost axial point E of the carcass is, for example, determined by tomography, with the tire mounted / inflated under nominal conditions.

[0064] Point F is then determined by an axial projection of point E onto the outer surface S of the tire.

[0065] The outer surface S of the tire describes a first portion from point F to point A, the latter being radially outside the circle Cl, of radius RI centered on the end 8 of the reversal of the carcass reinforcement layer.

[0066] The distance T measured between any point on the outer surface S of the tire and the main part of the carcass reinforcement layer, said distance being measured at any point along a direction normal to the main part of the carcass reinforcement layer, is equal to 4.7 mm and substantially constant over this portion between points F and A.

[0067] The radius RI of circle 1 is equal to 8.3 mm.

[0068] The outer surface S of the tire then extends radially inwards by an arc of a circle 12 of radius R2, itself tangent at B to an arc of a circle 13, of radius R3, the said arc of a circle extending the outer surface S of the tire to point C.

[0069] Point C is the point of tangency between the arc of circle 13 and the circle C2 centered on the outermost radial end of the stiffener.

[0070] Point C is radially inside point D, which is axially the outermost point of circle C2.

[0071] The radius R2 is equal to 90 mm.

[0072] The radius R3 is equal to 121 mm.

[0073] The distance between point F and the center of gravity of the rod is equal to 119 mm.

[0074] The radii R2 and R3 are therefore well within 50% and 125% of this distance between point F and the center of gravity of the rod.

[0075] The radial distance between point F and point A is equal to 37 mm.

[0076] Point G, visible in Figure 1, is the point, radially outside point F, from which the distance between a point on the outer surface S of the tire and the main part of the carcass reinforcement layer, measured at any point along a direction normal to the main part of the carcass reinforcement layer, is greater than the distance T.

[0077] The radial distance between point F and G is equal to 38 mm.

[0078] The radial distance between point F and point A is therefore much greater than 70% of the radial distance between point F and G.

[0079] According to the invention, the markings inscribed on the outer surface S of the tire are located between points A and B and therefore in the concave part of the outer surface S of the tire formed by an arc of a circle 12 whose radius R2 is equal to 90 mm.

[0080] Tests were conducted on a test machine to simulate tire friction against a curb. The tire was mounted on an 8.25x22.5 rim, inflated to 9 bar, and subjected to a load of 3500 kg. The tire was rolled against a curb with a raised edge of 140 mm and a setback of 30 mm, featuring a 20 mm radius fillet at its upper corner. During the test, the tire's axis of rotation was inclined at 1° towards the curb so that the friction between the tire and the curb was representative of urban use and sufficiently low to prevent the tire from mounting the curb.

[0081] The tires according to the invention, as described in Figures 1 and 2, are compared to reference tires with a more common outer surface profile. Such a tire profile is shown in Figure 3.

[0082] In this figure 3, which represents a tire 31 of the same dimensions, it appears that the area of ​​the bead 33 is similar to that of the tire according to the invention and that the structure of the carcass reinforcement layer 32 is identical, the latter being turned around a bead 34 to form a turning 37 reinforced by a stiffener 39. On the other hand, the profile of the outer surface of the tire 31 is different from that of the tire according to the invention.

[0083] In accordance with usual practices, the markings are inscribed on this reference tire in the outermost axial area of ​​the tire when it is mounted on a rim and inflated.

[0084] The tests were carried out for the tires according to the invention under conditions identical to those applied to the reference tires.

[0085] The tests consisted of evaluating the distance traveled by the tire when the markings became illegible. This involved a visual observation of the tire, with driving being interrupted regularly.

[0086] The tires according to the invention were stopped after approximately 15 km of rolling under friction due to sidewall wear, although the markings remained legible. For the reference tires, after approximately 3 km of rolling under friction, the markings were no longer legible.

[0087] The inventors also performed a simulation of this same rolling test to estimate, by calculation, the contact pressure values ​​observed at the markings for the tire according to the invention and for the reference tire. For the tire according to the invention, the pressure values ​​are evaluated on the concave portion 12 of the tire's outer surface, between points A and B as shown in Figure 2. For the reference tire, the pressure values ​​are evaluated on a portion of the tire's outer surface centered on the outermost axial point of the tire, with the tire mounted and inflated.

[0088] The results indicate an estimated pressure of approximately 0.09 daN / mm² 2 for the reference tire and a pressure rated at zero for the tire according to the invention.

[0089] These simulation-based assessments confirm the results obtained by machine testing and explain why the markings remain legible for longer with tires conforming to the invention.

[0090] Further tests were conducted to test endurance performance by rolling two planed tires on top of each other with a regulated pressure of 5.5 bar, and a load of 4571 daN at a speed of 50 km / h and an ambient temperature of 15°C for 20000 km.

[0091] The tires according to the invention exhibit results substantially identical to those of the reference tires, which shows a similar endurance performance.

[0092] The tires according to the invention thus allow, by limiting the risks of disappearance of markings, that these risks no longer be considered as a barrier to retreading or more simply as risks leading to the disposal of tires, which no longer meet the regulations imposing the legibility of certain markings.

Claims

DEMANDS 1 - Tire (1), comprising a radial carcass reinforcement (2), consisting of at least one carcass reinforcement layer formed of reinforcing elements, said tire comprising a crown reinforcement (5), itself radially capped by a tread (6), said tread (6) being joined to two beads (3) by means of two sidewalls, in a meridian section of said tire, radially internally at point (F), defined by the intersection of a straight line of axial orientation, passing through the axially outermost point (E) of the main part of the carcass reinforcement layer (2) and the outer surface (S) of the tire, the profile of the outer surface (S) of the tire comprising a concave portion such that the center of a circle inscribed in this concave portion is axially external to the outer surface (S) of the tire,characterized in that at least one regulatory marking of the tire is inscribed in the concave part. 2 - Tire (1) according to claim 1, characterized in that all the regulatory markings of the tire are inscribed in the concave part. 3 - Pneumatic (1) according to any one of claims 1 or 2, said at least one layer of carcass reinforcement elements (2) being anchored in each of the beads (3) by turning around a bead (4) to form a main part of the carcass reinforcement layer extending from one bead (4) to the other and a turning (7) of the carcass reinforcement layer (2) in each of the beads (3), characterized in that the circle inscribed in said concave part has a radius between 50% and 125% of the distance between the center of gravity of the bead (4) and point F. 4 - A tire (1) according to claim 1 or 2, said at least one layer of carcass reinforcement elements (2) being anchored in each of the beads (3) by folding around a bead (4) to form a main part of the carcass reinforcement layer extending from one bead (4) to the other, and a folding (7) of the carcass reinforcement layer (2) in each of the beads (3), said folding (7) of the carcass reinforcement (2) being reinforced by at least one layer of reinforcing or stiffening elements (9), characterized in that in a meridional cross-section of said tire, any point on the profile of the outer surface (S) of the tire, between point (F) and a point (A), is at a constant distance (T) from the main part of the carcass reinforcement layer (2), said distance being measured at any point along a direction normal to the main part of the frame reinforcement layer (2),point (A) is radially outside a first circle (Cl) of radius RI centered on the end (8) of the inversion (7) of the reinforcement layer of the frame (2), RI being between 8 and 13 mm, radially inside point (A), the outer surface (S) of the tire extends by an arc of a circle of radius R2 whose center is axially outside the surface (S) of the tire, and whose radius R2 is between 50% and 125% of the distance between point (F) and the center of gravity of the bead (4), the arc of a circle of radius R2 is tangent at its innermost radial end (B) to an arc of a circle of radius R3 whose center is axially inside the surface (S) of the tire, and extending the outer surface (S) of the tire radially inwards to the point (C), said point (C) being a point of tangency between the arc of a circle of radius R3 and the circle (C2) of radius RI centered on the outermost radial end (10) of the stiffener (9), said point (C) being radially interior to the axially outermost point (D) of the circle (C2), the radius R3 being between 50% and 125% of the distance between point (F) and the center of gravity of the rod (4). 5 - Pneumatic (1) according to claim 4, characterized in that the radius R2 is greater than 1.5 times the radius RI and preferably less than 8 times the radius RI. 6 - Pneumatic (1) according to claim 4 or 5, characterized in that the distance (T), measured along a direction normal to the main part of the carcass reinforcement layer, is greater than 3 mm and preferably less than 7 mm. 7 - Tire (1) according to any one of claims 4 to 6, characterized in that the radial distance between point (F) and point (A) is greater than 70% of the radial distance between point (F) and the radially outermost point (G) of the outer surface (S) of the tire, for which the distance, measured in a direction normal to the main part of the carcass reinforcement layer (2), between said main part of the carcass reinforcement layer (2) and the surface (S) is equal to (T), said distance between any point, of the outer surface (S) of the tire, radially included between points (F) and (G) and the main part of the carcass reinforcement layer (2) being constant. 8 - Pneumatic (1) according to any one of claims 4 to 7, characterized in that the outermost radial end (10) of the stiffener (9) is radially outside the end (8) of the turn (7) of the reinforcement layer of the carcass (2). 9 - Pneumatic (1) according to one of the preceding claims, characterized in that the reinforcement elements of said at least one carcass reinforcement layer (2) are cables with at least two layers, at least one inner layer being sheathed with a layer made of a non-crosslinkable, crosslinkable or crosslinked rubber composition, preferably based on at least one diene elastomer. 10 - Pneumatic (1) according to one of the preceding claims, characterized in that, in any meridian plane, in each bead, the pneumatic (1) comprises a restraint reinforcement surrounding the rod (4) and a volume of rubbery mixture directly in contact with the rod (4).

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