Tyre comprising a corrugated crown layer and a sidewall stiffening insert

Abstract

The invention relates to a tyre (10) not suitable for running flat, comprising a crown block (12), two beads (32), and two sidewalls (30) connecting each bead (32) to the crown block (12). The crown block (12) comprises a crown reinforcement (16) including a corrugated crown layer (24, 26, 28) comprising corrugations. The sidewall (30) comprises a sidewall insert (90) containing a so-called rigid elastomeric composition (92) having a modulus at 10% elongation greater than or equal to 6 MPa and a maximum thickness (Emax) less than or equal to 5.0 mm.

Description

Tire comprising a corrugated crown layer and a sidewall stiffening insert

[0001] The present invention relates to a tire. By tire is meant a bandage intended to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized to a pressure higher than atmospheric pressure. A tire according to the invention has a structure of substantially toroidal shape of revolution around a main axis of the tire.

[0002] EP3529087 discloses a tire comprising a crown block, two beads, two sidewalls connecting each bead to the crown block. The crown block comprises a tread and a crown reinforcement arranged radially inside the tread. The crown reinforcement comprises a working reinforcement comprising two working layers and a hoop reinforcement comprising a hoop layer, the hoop reinforcement being arranged radially outside the working reinforcement. Each working and hoop layer comprises several corrugations. Each corrugation of each crown layer comprises a crown and first and second bottoms adjacent to said crown arranged such that said crown is arranged axially between said first and second bottoms and such that said crown is arranged radially outside each first and second bottom.Due to the presence of undulations, each layer of the crown reinforcement having at least one undulation is said to be a wavy crown layer.

[0003] Such a tire has, due to the corrugated crown layers, a crown block having very high lateral stiffness, vertical stiffness and drift stiffness and, in any case, much higher than those of a similar tire comprising substantially cylindrical crown layers devoid of corrugations.

[0004] Despite these very high rigidities, it was surprisingly observed that vehicles equipped with such tires did not exhibit behavior at the level expected with corrugated crown layers, although this level of behavior was nevertheless higher than the level of behavior of a tire without a corrugated crown layer.

[0005] The invention aims to improve the behavior of vehicles equipped with tires comprising at least one corrugated crown layer.

[0006] To this end, the subject of the invention is a tire not suitable for running flat comprising a crown block, two beads, two sidewalls connecting each bead to the crown block, the crown block comprising a tread and a crown reinforcement arranged radially inside the tread, the crown reinforcement comprising a central portion of axial width equal to 80% of the axial width of the crown reinforcement and axially centered on the median plane of the tire, the crown reinforcement comprising at least one crown layer, called corrugated, comprising reinforcing elements embedded in a polymer matrix, said corrugated crown layer comprising, in the central portion of the crown reinforcement, at least one corrugation, the or each corrugation of said corrugated crown layer comprising a crown of said corrugated crown layer and first and second bottoms of said corrugated crown layer adjacent to said crown arranged so that: - said top is arranged axially between said first and second bottoms, - said crown is arranged radially outside each first and second bottom, tire comprising a sidewall insert arranged axially between an external surface of at least one of the sidewalls and an internal surface of said sidewall, the sidewall insert comprising at least one so-called rigid elastomeric composition, the or each rigid elastomeric composition of the sidewall insert having a modulus at 10% extension greater than or equal to 6 MPa, the maximum thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions being less than or equal to 5.0 mm.

[0007] In order to achieve the invention, the inventors had to understand why the behavior obtained was not at the expected level. After numerous tests, the inventors determined that the sidewalls of the tire form a flexible portion between two rigid portions formed, on the one hand, by the crown reinforcement and, on the other hand, by each bead.

[0008] Indeed, on the one hand, each bead, due to its function as an interface with the tire mounting support, for example a rim, is rigid, in particular due to the materials from which it is made as well as its significant thickness. Among these materials, we will notably mention the reinforcing elements, generally metallic or even elastomeric compositions having high rigidity, for example moduli at 10% extension greater than 20 MPa.

[0009] On the other hand, since the crown reinforcement has at least one corrugated crown layer, the crown reinforcement is also relatively rigid, in any case more rigid than a crown reinforcement without a corrugated crown layer.

[0010] Thus, in the case where a significant force is exerted on the tire, the rigid portions formed by the crown reinforcement and the beads transmit a relatively large proportion of this force to the least rigid part of the tire, here each sidewall. However, as each sidewall is arranged radially between each bead and the top block including the top reinforcement, each flank bends with a relatively large amplitude, hence the behavior not at the expected level.

[0011] Once the reason for the behavior was understood, the inventors behind the invention also had to find the technical solution to achieve the best performance compromise.

[0012] Thus, the inventors discovered that the use of a sidewall insert having a relatively high rigidity, in any case greater than the rigidity of the elastomeric compositions usually present in the sidewalls of tires, made it possible to reduce the amplitude of the flexion of each sidewall in the case of a significant force exerted on the tire. This improves the behavior of the vehicle.

[0013] Furthermore, the use of a sidewall insert in accordance with the invention has the advantage of presenting a better compromise between its manufacturing cost and its behavior unlike other solutions such as, for example, the use of a reinforced carcass reinforcement. Indeed, the sidewall insert replacing at least in part a material already existing in the sidewall of the tire, the manufacturing cost of the tire according to the invention is not significantly increased compared to a tire without the sidewall insert.

[0014] Concerning the modulus at 10% extension, commonly called MA10, it is the elastic modulus of the mixture measured during a uniaxial tensile experiment, at an elongation value of 0.1 (i.e. 10% elongation, expressed as a percentage). A constant uniaxial tensile speed is imposed on the specimen, and its elongation and stress are measured. The measurement is carried out using an “INSTRON” type tensile testing machine (registered trademark), at a temperature of 23°C, and a relative humidity of 50% (ISO 23529 standard). The conditions for measuring and using the results to determine the elongation and stress are as described in standard NF ISO 37: 2012-03. The stress is determined for an elongation of 0.1 and the modulus of elasticity under tension at 10% elongation is calculated by calculating the ratio of this stress value to the elongation value.The person skilled in the art will know how to choose and adapt the dimensions of the test piece according to the quantity of mixture accessible and available, particularly in the case of taking samples from the tire.

[0015] The elastomeric composition of the sidewall insert is based on one or more elastomers. It may also include fillers and other components commonly used in the field of tire compounds.

[0016] The tire according to the invention is not a tire suitable for running flat. A tire suitable for running flat is suitable for running in which the pressure of the internal cavity of the tire is equal to the pressure atmospheric (by misuse of language, it is often said that the pressure is zero when it is the excess pressure in relation to atmospheric pressure that is zero). A tire suitable for running flat includes self-supporting sidewalls, i.e. capable of carrying, in the presence of a pressure equal to atmospheric pressure, the same load, for example the nominal load as indicated in the manual of the standard of the European Tyre and Rim Technical Organization or "ETRTO", 2021, that the tire is capable of carrying when inflated to its usual inflation pressure, for example its nominal inflation pressure as indicated in the manual of the ETRTO standard, 2021, and this for a mileage greater than or equal to a certain threshold at a speed greater than or equal to 80 km / h.Thus, a tire suitable for run-flat operation is such that, under its nominal load as indicated in the ETRTO, 2021 standard manual and under atmospheric pressure, the or each sidewall cannot fold on itself so as to bring two distant portions of the tire into contact. On the contrary, a tire not suitable for run-flat operation is such that, under its nominal load as indicated in the ETRTO, 2021 standard manual and under atmospheric pressure, the or each sidewall folds on itself so as to bring two distant portions of the tire into contact.

[0017] A tire suitable for running flats preferably has a specific marking indicating the tire's ability to run flat. For example, the following acronym markings are used, but this list is not exhaustive: "ZP" for "Zero Pressure", "SST" for "Self Supporting Technology", "SSR" for "Self Supporting Runflat Tire", "RF" for "Run Flat", "RFT" for "Run Flat Tire", "EXT" for "EXTended", "ZP-SR" for "Zero Pressure Short Range" or "ZPS" for "Zero Pressure System". Another specific marking indicating the tire's ability to run flats is the presence of the letter "F" in the tire dimension. Thus, tires with dimensions 225 / 40R18 or 225 / 40ZR18, if they are suitable for running flats, have the markings 225 / 40RF18 or 225 / 40ZRF18.

[0018] The maximum thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions is the maximum value of the thicknesses of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions, the thickness being able to be constant or variable. A thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions is defined, in a meridian section plane, as the thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions at a point on the internal surface of the tire. The thickness of the elastomeric composition rigid or of the assembly of rigid elastomeric compositions at this point of the internal surface is the straight distance along the normal to the internal surface at said point of the internal surface between the most radially inner point of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions and the most radially outer point of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions, these points of the sidewall insert being aligned along the normal with said point of the internal surface.

[0019] The inner surface delimits the internal cavity of the tire. The internal cavity is intended to be pressurized by the inflation gas once the tire is mounted on a mounting support, for example a rim. The inner surface of the sidewall is therefore the part of the sidewall delimiting the internal cavity of the tire.

[0020] The outer surface is the surface of the tire in contact with the air at atmospheric pressure and visible from the outside of the tire. The outer surface of the sidewall is therefore the part of the sidewall in contact with the air at atmospheric pressure and visible from the outside of the tire.

[0021] In a preferred embodiment, the or each sidewall insert comprises a rigid elastomeric composition. In certain variants, the or each sidewall insert is made of a rigid elastomeric composition. In other variants, the or each sidewall insert comprises a rigid elastomeric composition and one or more elastomeric composition(s), called flexible, whose modulus at 10% extension is strictly less than 6 MPa. In these embodiments, the maximum thickness is the thickness of the rigid elastomeric composition.

[0022] However, in other embodiments, it may be envisaged that the or each sidewall insert comprises several rigid elastomeric compositions. In these embodiments, the maximum thickness is the maximum thickness of the assembly of the rigid elastomeric compositions, i.e. the maximum value of the sum of the thicknesses of each rigid elastomeric composition measured along the same normal to the internal surface of the tire. In certain variants of these embodiments comprising several rigid elastomeric compositions, all the elastomeric compositions of the sidewall insert are rigid elastomeric compositions. In other variants of these embodiments comprising several rigid elastomeric compositions, the sidewall insert comprises, in addition to the rigid elastomeric compositions, one or more elastomeric composition(s), called flexible, whose modulus at 10% extension is strictly less than 6 MPa.In these other variants, the maximum thickness does not take into account the thickness of the or each flexible elastomeric composition, the maximum thickness being defined as the thickness. maximum assembly of rigid elastomeric compositions.

[0023] By funds adjacent to a summit, it is understood that no other fund is axially arranged between the summit and each adjacent fund.

[0024] Except where the or each undulating top layer describes a polygonal line comprising rectilinear segments in each meridional section plane, each undulation comprises two inflection points arranged axially between the top and each first and second bottom. An inflection point means a point where, in a meridional section plane, the direction of curvature of the or each undulating top layer changes.

[0025] The axial width of the crown reinforcement is the width in the axial direction of the layer of the crown reinforcement having the greatest width in the axial direction. The width in the axial direction is the distance in the axial direction between the two axial ends of a layer. The or each layer of the crown reinforcement may be axially continuous or axially discontinuous between its two axial ends. Typically, the crown reinforcement of a passenger vehicle tire comprises a hoop reinforcement and a working reinforcement arranged radially inside the hoop reinforcement, the hoop reinforcement being radially arranged between the tread and the working reinforcement, the hoop reinforcement comprising at least one hoop layer and the working reinforcement comprising at least one working layer.

[0026] The central part is axially centered on the median plane of the tire means that each axial end of the central part is located at an axial distance from the median plane of the tire equal to 40% of the axial width of the crown reinforcement.

[0027] By reinforcing element is meant an element allowing the mechanical reinforcement of the polymer matrix in which this reinforcing element is intended to be embedded.

[0028] Preferably, each reinforcing element is wire-like, that is to say that each reinforcing element has a length at least 10 times greater than the largest dimension of its section regardless of the shape of the latter: circular, elliptical, oblong, polygonal, in particular rectangular or square or oval. In the case of a rectangular section, the wire-like reinforcing element has the shape of a strip.

[0029] The matrix is ​​said to be polymeric because it is based on a polymeric composition, this polymeric composition being able to comprise one or more polymers, for example chosen from thermoplastic polymers, thermosetting polymers, elastomers, thermoplastic elastomers, but also fillers and others components commonly used in the field of tire compositions, in particular compositions for embedding reinforcing elements.

[0030] The tire according to the invention has a substantially toric shape around an axis of revolution substantially coincident with the axis of rotation of the tire. This axis of revolution defines three directions conventionally used by those skilled in the art: an axial direction, a circumferential direction and a radial direction.

[0031] Axial direction means the direction substantially parallel to the axis of revolution of the tire, i.e. the axis of rotation of the tire.

[0032] Circumferential direction means the direction which is substantially perpendicular to both the axial direction and a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[0033] Radial direction means the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[0034] By median plane of the tire (noted M), we mean the plane perpendicular to the axis of rotation of the tire which is located at the axial midpoint of the two beads and passes through the axial center of the crown reinforcement.

[0035] The equatorial circumferential surface of the tire means the association of the planes passing, in each meridian section plane, through the equator (denoted E) of the tire and perpendicular to the median plane and to the radial direction. The equator of the tire is, in a meridian section plane (plane perpendicular to the circumferential direction and parallel to the radial and axial directions) the axis parallel to the axis of rotation of the tire and located equidistant between the radially outermost point of the tread intended to be in contact with the ground and the radially innermost point of the tire intended to be in contact with a support, for example a rim, the distance between these two points being equal to H.

[0036] Meridian plane means a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0037] By radially inner, respectively radially outer, is meant closer to the tire's axis of rotation, respectively further from the tire's axis of rotation. By axially inner, respectively axially outer, is meant closer to the tire's median plane, respectively further from the tire's median plane.

[0038] By bead is meant the portion of the tire intended to allow the tire to be attached to a mounting support, for example a wheel comprising a rim. Thus, each bead is in particular intended to be in contact of a rim hook allowing its attachment. Thus, the radially outer end of the outer surface of the tire bead is defined as the point on the radially outermost tire surface in contact with a tire measuring rim according to the ETRTO standard manual, 2021 when the tire is inflated to its nominal pressure on this measuring rim.

[0039] Any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from more than a to less than b (i.e., excluding the limits a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (i.e., including the strict limits a and b).

[0040] The tires are, in certain preferred embodiments of the invention, intended for passenger vehicles as defined within the meaning of the ETRTO standard manual, 2021. Such a tire has a section in a meridian cutting plane characterized by a section height H and a nominal section width or bead thickness S within the meaning of the ETRTO standard manual, 2021 such that, optionally, the H / S ratio, expressed as a percentage, is at most equal to 90, preferably at most equal to 50 and more preferably at most equal to 40 and is at least equal to 20, preferably at least equal to 25, and the nominal section width S is at least equal to 155 mm, preferably at least equal to 205 mm and more preferably at least equal to 225 mm and at most equal to 385 mm, preferably at most equal to 335.In addition, the diameter at hook D, defining the diameter of the tire mounting rim, is at least 12 inches, preferably at least 16 inches and at most 24 inches.

[0041] For any crown layer, a continuous surface, called the radially outer surface (SRE) of said layer, is defined, passing through the most radially outer point of each reinforcing element, as well as a continuous surface, called the radially inner surface (SRI) of said layer, passing through the most radially inner point of each reinforcing element. The radial distances between a layer of the crown reinforcement comprising reinforcing elements and any other point are measured from one or the other of these surfaces and in such a way as not to include the radial thickness of said layer. If the other measuring point is arranged radially outside the reinforcing element layer, the radial distance is measured from the radially outer surface SRE at this point. If the other measuring point is arranged radially inside the reinforcing element layer, the radial distance is measured from the radially inner surface SRI at this point.

[0042] In preferred embodiments, the maximum radial amplitude of the or each corrugation is greater than or equal to 1.0 mm, preferably 1.5 mm. In other preferred embodiments, the maximum radial amplitude of the or each ripple is less than or equal to 3.0 mm, preferably 2.5 mm.

[0043] By maximum radial amplitude of a corrugation is meant the straight distance in the radial direction between the point of the radially outer surface SRE of the top of the corrugation and the point of the radially outer surface SRE of the radially innermost bottom of one of the first and second bottoms of said corrugation.

[0044] In preferred embodiments, over at least 10%, preferably over at least 20% of the axial width of the corrugated crown layer separating each first and second bottom of the or each corrugation, the radial distance between the radially outer surface SRE and the point of the radially outer surface SRE of the radially innermost bottom of one of the first and second bottoms of the or each corrugation is greater than or equal to 1.0 mm, preferably 1.5 mm. In other preferred embodiments, over at least 10%, preferably over at least 20% of the axial width of the corrugated crown layer separating each first and second bottom of the or each corrugation, the radial distance between the radially outer surface SRE and the point of the radially outer surface SRE of the radially innermost bottom of one of the first and second bottoms of the or each corrugation is less than or equal to 3.0 mm, preferably 2.5 mm.

[0045] In preferred embodiments, the corrugated crown layer is the radially outermost layer of the crown reinforcement. In some passenger vehicle tire embodiments, the radially outermost layer of the crown reinforcement is the hoop layer.

[0046] In advantageous embodiments, the or each corrugated top layer comprises a plurality of corrugations.

[0047] Preferably, the or each corrugated crown layer extends axially from one side to the other of the median plane of the tire.

[0048] In an optional embodiment, each sidewall comprises a sidewall insert arranged axially between the outer surface of said sidewall and the inner surface of said sidewall, each sidewall insert comprising at least one so-called rigid elastomeric composition, the or each rigid elastomeric composition of each sidewall insert having a modulus at 10% extension greater than or equal to 6 MPa, the maximum thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions of each sidewall insert being less than or equal to 5.0 mm.

[0049] Thus, in a first variant, it will be possible to have two sidewall inserts arranged in the two sidewalls of the tire, these two sidewall inserts having the same maximum thickness and the same rigid elastomeric composition(s).

[0050] In a second variant, we could have two side inserts arranged in the two sidewalls of the tire, these two sidewall inserts having different maximum thicknesses and / or one or more rigid elastomeric compositions having different moduli at 10% extension. In particular, in the case where the tire has a mounting direction indicating an outer side and an inner side for its mounting on a vehicle, preference will be given to the case in which the sidewall insert intended to be on the outer side has a maximum thickness and / or one or more rigid elastomeric compositions having a modulus at 10% extension greater than those of the sidewall insert intended to be on the inner side.

[0051] In an optional embodiment, the tread comprising at least one rib and first and second cutouts adjacent to the rib, the top of said corrugation of said corrugated crown layer is arranged directly above the rib and each first and second bottom of said corrugation of said corrugated crown layer is arranged directly above each first and second cutout adjacent to the rib respectively.

[0052] The portion of the corrugated crown layer arranged directly above a rib or a cutout is the axial portion of the corrugated crown layer delimited by axial ends defined by two circumferential planes perpendicular to the axis of rotation of the tire and passing respectively through the axial ends of the rib or the cutout. Thus, a top of a corrugation of the corrugated crown layer is directly above the rib if this top is axially between the two circumferential planes passing through the axial ends of the rib and described above. Similarly, a bottom of a corrugation of the corrugated crown layer is directly above a cutout if this bottom is axially between the two circumferential planes passing through the axial ends of the cutout and described above.

[0053] By cutout adjacent to the rib, it is understood that no other cutout is axially arranged between the cutout and the rib.

[0054] A cutout is either a groove or an incision and forms a space opening onto the running surface.

[0055] An incision or groove has, on the rolling surface, two main characteristic dimensions: a width and a curvilinear length such that the curvilinear length is at least twice the width. An incision or groove is therefore delimited by at least two main lateral faces determining its curvilinear length and connected by a bottom face, the two main lateral faces being distant from each other by a non-zero distance, called the width of the cut.

[0056] The width of a cut is, on a new tire, the maximum distance between the two main lateral faces measured, in the case where the cutout does not include a chamfer, at a radial dimension coincident with the rolling surface, and in the case where the cutout includes a chamfer, at the radial dimension most radially external to the cutout and radially internal to the chamfer. The width is measured substantially perpendicular to the main lateral faces.

[0057] The axial width of a cutout is measured along the axial direction of the tire, for example in a meridian cutting plane of the tire.

[0058] An incision is such that the distance between the main lateral faces is suitable to allow at least partial contact of the main lateral faces delimiting said incision when passing through the contact area, in particular when the tire is in new condition and under normal driving conditions, including in particular the fact that the tire is at nominal load and nominal pressure.

[0059] A groove is such that the distance between the main lateral faces is such that these main lateral faces cannot come into contact with each other under normal driving conditions, including in particular the fact that the tire is at nominal load and nominal pressure.

[0060] A cutout can be transverse or circumferential.

[0061] A transverse cut is such that the cut extends in a mean direction forming an angle strictly greater than 30°, preferably greater than or equal to 45° with the circumferential direction of the tire. The mean direction is the shortest curve joining the two ends of the cut and parallel to the tread surface. A transverse cut may be continuous, i.e. not interrupted by a tread block or another cut such that the two main lateral faces determining its length are uninterrupted over the length of the transverse cut. A transverse cut may also be discontinuous, i.e. interrupted by one or more tread blocks and / or one or more cuts such that the two main lateral faces determining its length are interrupted by one or more tread blocks and / or one or more cuts.

[0062] A circumferential cut is such that the cut extends in a mean direction forming an angle less than or equal to 30°, preferably less than or equal to 10° with the circumferential direction of the tire. The mean direction is the shortest curve joining the two ends of the cut and parallel to the tread surface. In the case of a continuous circumferential cut, the two ends coincide with each other and are joined by a curve forming a complete turn of the tire. A circumferential cut may be continuous, i.e. not interrupted by a tread block or another cut such that the two main lateral faces determining its length are uninterrupted over the entire turn of the tire. A circumferential cut may also be discontinuous, i.e. interrupted by one or more tread blocks and / or one or more cuts such that the two main lateral faces determining its length are interrupted by one or more tread blocks and / or one or more cuts over the entire turn of the tire.

[0063] In the case of a circumferential cutout located outside the median plane of the tire, the lateral faces are called axially inner faces and axially outer face, the axially inner face being arranged, at a given azimuth, axially inside the axially outer face relative to the median plane.

[0064] Each circumferential cutout comprises axially inner and outer axial ends. Whether in the case of a circumferential cutout without a chamfer or with a chamfer, each axially inner and outer end is located respectively on each axially inner or outer edge.

[0065] In the case of a transverse cut, the side faces are called the leading face and the trailing face, the leading face being the one whose edge, for a given circumferential line, enters the contact area before the edge of the trailing face.

[0066] In embodiments, the or each circumferential cutout is provided with chamfers. A chamfer of a circumferential cutout may be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a flat face inclined relative to the axially inner and outer face which it extends to the axially inner or outer edge axially delimiting the circumferential cutout. A rounded chamfer is formed by a curved face connecting tangentially to the axially inner or outer face which it extends. A chamfer of a circumferential cutout is characterized by a height and a width equal respectively to the radial distance and the axial distance between the common point between the axially inner or outer face extended by the chamfer and the axially inner or outer edge axially delimiting the circumferential cutout.

[0067] In embodiments, the or each transverse cutout is provided with chamfers. In other words, each transverse cutout being delimited radially by leading and trailing faces circumferentially delimiting said transverse cutout and connected to each other by a bottom face radially inwardly delimiting said transverse cutout. A chamfer of a transverse cutout may be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a flat face inclined relative to the leading or trailing face which it extends to the leading or trailing edge circumferentially delimiting the transverse cutout. A rounded chamfer is formed by a curved face connecting tangentially to the leading or trailing face which it extends. A chamfer of a transverse cutout is characterized by a height and a width equal respectively to the radial distance and to the distance in a direction perpendicular to the leading or trailing faces between the common point between the leading or trailing face extended by the chamfer and the leading or trailing edge circumferentially delimiting the transverse cutout.

[0068] The depth of a cut is, on a new tire, the maximum radial distance between the bottom of the cut and its projection onto the ground when the tire is rolling. The maximum value of the depths of the cuts is called the tread height.

[0069] In embodiments in which each first and second adjacent circumferential cutout is relatively wide, particularly in the case of passenger vehicle tires, each first and second adjacent circumferential cutout has an axial width greater than or equal to 1.0 mm, preferably greater than or equal to 4.0 mm and more preferably ranging from 4.0 mm to 20.0 mm.

[0070] In embodiments in which each first and second adjacent circumferential cutout is relatively deep, particularly in the case of passenger vehicle tires, each first and second adjacent circumferential cutout has a depth greater than or equal to 50% of the tread height Hs. Thus, preferably, each first and second adjacent circumferential cutout has a depth ranging from 4.0 mm to the tread height.

[0071] In highly advantageous embodiments, the tread comprising a plurality of ribs and a plurality of cutouts, each rib of the plurality of ribs having first and second adjacent cutouts of the plurality of cutouts, the corrugated crown layer comprises, in the central portion of the crown reinforcement, a plurality of corrugations, the top of each corrugation of said corrugated crown layer is arranged directly above one of the ribs and each first and second bottom of each corrugation of said corrugated crown layer is arranged directly above each first and second cutout adjacent to said rib.

[0072] In an advantageous embodiment, each first and second cutout adjacent to the or each rib is a circumferential cutout.

[0073] In advantageous variants in which the corrugated crown layer is the radially outermost layer of the crown reinforcement, the difference between: - the minimum radial distance between the or each peak of the or each corrugation of the radially outermost layer of the crown reinforcement and the rolling surface, - the depth of the or each circumferential cutout in line with which each first and second bottom of said or each corrugation is arranged is less than or equal to 2 mm.

[0074] The minimum radial distance between the top of the or each corrugation and the running surface is here measured between the radially outer surface SRE of said corrugated crown layer and the running surface.

[0075] In advantageous embodiments, the modulus at 10% extension of the or each rigid elastomeric composition is less than or equal to 20 MPa, preferably 15 MPa and more preferably 13 MPa. Although improving the behavior of the vehicle, excessively high rigidity can nevertheless reduce the comfort of the vehicle. In addition, excessively high rigidity can degrade the flattening, which leads to a reduction in the surface area of ​​the contact patch. Thus, it is preferable not to use a sidewall insert that is too rigid.

[0076] In advantageous embodiments, the maximum thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions ranges from 1.0 to 5.0 mm, preferably from 1.0 to 3.5 mm and more preferably from 1.0 to 2.5 mm and even more preferably from 1.2 to 1.7 mm. Although having a rigidity significantly greater than the rigidities of the compositions usually used in the sidewalls of tires, the greater the maximum thickness, the more the behavior of the vehicle is improved. However, beyond a maximum thickness that is too great, the comfort of the vehicle is deteriorated on the one hand, and the flattening on the other hand, which leads to a reduction in the surface area of ​​the contact patch.

[0077] In also advantageous embodiments, the or each sidewall having a minimum thickness at a point I, the thickness of the sidewall at a point of the internal surface being defined as the straight distance along the normal to the internal surface at said point of the internal surface between said point of the internal surface and a point of the external surface of the tire aligned along the normal with said point of the internal surface, the point of the internal surface at which the thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions is maximum is arranged radially between: - a radially external straight line formed by the normal to the internal surface passing through a point on the internal surface arranged 10 mm radially outside point I, - a radially inner straight line formed by the normal to the inner surface passing through a point on the inner surface arranged 10 mm radially inside point I.

[0078] In other words, the thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions is maximum near the area in which the sidewall has the smallest thickness. Indeed, at equal rigidity, the sidewall bends the most where it has the smallest thickness. Thus, it is advantageous, to effectively improve the behavior of the vehicle, to stiffen the sidewall in this potential area of ​​strong bending.

[0079] Optionally, the thickness of the rigid elastomeric composition or of the assembly of rigid elastomeric compositions is maximum radially outside the equator of the tire.

[0080] In advantageous embodiments, the radially outer end of the sidewall insert is arranged radially outside the equator of the tire.

[0081] Advantageously and optionally, the radially outer end of the flank insert is arranged radially and axially inside a straight line normal to the internal surface and passing through the axially outer end of the axially widest crown layer of the crown reinforcement.

[0082] Indeed, by extending beyond the axially outer end of the axially widest crown layer, the sidewall insert would have the effect of unnecessarily increasing the mass and rolling resistance of the tire.

[0083] In embodiments, the radially outer end is the radially outer end of the rigid elastomeric composition or the radially outermost end of the radially outer ends of the rigid elastomeric compositions of the assembly. In other embodiments, the radially outer end is the radially outermost end of the radially outer ends of the rigid or flexible elastomeric compositions of the insert.

[0084] In also advantageous embodiments, the radially inner end of the sidewall insert is arranged radially inside the equator of the tire.

[0085] Advantageously and optionally, the radially inner end of the flank insert is arranged radially and axially outside a straight line normal to the inner surface and passing through the radially outer end of the outer surface of the tire bead.

[0086] Indeed, it is pointless for the sidewall insert to extend too far radially inwards, particularly in the bead, since this area of ​​the tyre is, as indicated in the preamble, already sufficiently rigid. This would only make the tyre unnecessarily heavier.

[0087] In embodiments, the radially inner end is the radially inner end of the rigid elastomeric composition or the radially innermost end of the radially inner ends of the rigid elastomeric compositions of the assembly. In other embodiments, the radially inner end is the radially innermost end of the radially inner ends of the rigid or flexible elastomeric compositions of the insert.

[0088] Optionally but advantageously, the or each flank insert has a generally crescent-shaped section. Thus, the width of the section of the flank insert is minimal at its radially inner and outer ends and is maximal between the latter.

[0089] Optionally, the tire comprises a carcass reinforcement comprising at least one carcass layer anchored in the or each bead and extending radially in the or each sidewall and axially in the crown block radially inside the crown reinforcement.

[0090] Optionally, the or each carcass layer is delimited axially by two axial ends and comprises carcass reinforcement elements extending axially from one axial end to the other of said carcass layer in a main direction forming, optionally and preferably, with the circumferential direction of the tire, an angle, in absolute value, greater than or equal to 60°, preferably ranging from 80° to 90°.

[0091] In some embodiments, the tire comprises an inner sealing layer supporting the inner surface of the tire, the sidewall insert is arranged axially between the inner sealing layer and the axially innermost carcass layer.

[0092] In other embodiments, it may be envisaged that the sidewall insert is arranged axially between the axially outermost carcass layer and the outer surface of the tire.

[0093] In certain variants, the carcass reinforcement comprises a single layer of carcass anchored in the or each bead and extending radially in each sidewall and axially in the crown block radially inside the crown reinforcement. In these variants, the invention makes it possible in particular to avoid the addition of a second carcass layer or even the use of reinforced carcass reinforcement elements in order to improve the behavior of the vehicle. By single carcass layer anchored in the or each bead, it is understood that the carcass reinforcement is, with the exception of the carcass layer, devoid of any layer reinforced by reinforcing elements and anchored in the or each bead. The reinforcing elements of such reinforced layers excluded from the carcass reinforcement of the tire include metallic reinforcing elements and textile reinforcing elements. Very preferably, the carcass reinforcement is constituted by the single carcass layer. Even more preferably, the tire is devoid of a sidewall reinforcing layer extending at least radially in each sidewall and having: - a radially inner end arranged radially inside the equator of the tire - a radially outer end arranged radially outside the equator of the tire.

[0094] Thus, the excluded sidewall reinforcement layers are discontinuous under the crown of the tire. An excluded sidewall reinforcement layer is not anchored in a bead of the tire. Thus, the radially inner end of the excluded sidewall reinforcement layer is arranged radially outside the bead.

[0095] In other variants, the carcass reinforcement comprises first and second carcass layers anchored in the or each bead and extending radially in each sidewall and axially in the crown block radially inward to the crown reinforcement, the sidewall insert is arranged axially inside the first carcass layer. In these other variants, the invention makes it possible in particular to avoid the use of a sidewall reinforcement layer or the use of reinforced carcass reinforcement elements in order to improve the behavior of the vehicle. As described above, it may be envisaged to arrange the sidewall insert axially inside the axially innermost carcass layer. It may also be envisaged to arrange the sidewall insert axially between the first carcass layer and the second carcass layer.

[0096] In advantageous embodiments, the crown reinforcement comprises a working reinforcement comprising at least one working layer and a hoop reinforcement comprising at least one hoop layer, the hoop reinforcement being arranged radially outside the working reinforcement, the crown block is preferably devoid of an annular reinforcing structure.

[0097] In advantageous embodiments, the crown reinforcement comprises a working reinforcement comprising at least one working layer and a hooping comprising at least one hooping layer, the hooping reinforcement being arranged radially outside the working reinforcement, the or each hooping layer comprises, in the central part of the crown reinforcement, at least one corrugation.

[0098] Optionally, the or each hoop layer is delimited axially by two axial ends. The or each hoop layer comprises one or more hoop reinforcement elements wound circumferentially helically so as to extend axially from one axial end to the other of the hoop layer in a main direction. Optionally and preferably, the main direction forms, with the circumferential direction of the tire, an angle, in absolute value, less than or equal to 10°, preferably less than or equal to 7° and more preferably less than or equal to 5°.

[0099] Optionally, the or each working layer is delimited axially by two axial ends. The or each working layer comprises working reinforcement elements extending axially from one axial end to the other substantially parallel to each other in a main direction which, optionally and preferably, forms, with the circumferential direction of the tire, an angle in absolute value, strictly greater than 10°, preferably ranging from 15° to 50° and more preferably ranging from 25° to 45°.

[0100] In even more advantageous embodiments, the or each working layer comprises at least one corrugation.

[0101] Preferably, the or each hoop and work reinforcement element is a wire reinforcement element.

[0102] Preferably, the inner surface does not have, when the tire is inflated to its nominal pressure, an inflection point arranged in line with the crown reinforcement. The part of the inner surface arranged in line with the crown reinforcement is the part of the inner surface arranged axially between the axial limits of the axially widest crown layer projected radially onto the inner surface.

[0103] Preferably, in each meridian plane, the or each central rib has a rolling surface intended to come into contact with the ground that is substantially flat. By substantially flat, it is meant that the radial distance between the radially outermost point(s) of the rolling surface of said central rib and the radially innermost point(s) of the rolling surface is strictly less than 0.2 mm, preferably less than or equal to 0.1 mm, preferably substantially zero. A central rib is a rib arranged axially between two adjacent circumferential cutouts.

[0104] The invention will be better understood by reading the description which follows, given solely by way of non-limiting example and made with reference to the drawings in which: Figure 1 is a view, in a meridian section plane parallel to the axis of rotation of the tire, of a tire according to a first embodiment of the invention, Figure 2 is a detail view of one of the sidewalls of the tire of Figure 1, Figure 3 is a detail view of the crown block of the tire of Figure 1, Figure 4 is a view similar to that of Figure 1 of a tire according to a second embodiment of the invention, and Figure 5 is a view similar to that of Figure 1 of a tire according to a third embodiment of the invention.

[0105] In the figures relating to the tire, a reference X, Y, Z is shown corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions of a tire.

[0106] Figure 1 shows a tire, in accordance with the invention and designated by the general reference 10. The tire 10 has a substantially toric shape around an axis of revolution substantially parallel to the axial direction Y. The tire 10 is intended for a passenger vehicle and has dimensions 245 / 35 R20. The tire 10 is not suitable for running flat. In the various figures, the tire 10 is shown in new condition, that is to say not having yet been driven.

[0107] The tire 10 comprises a crown block 12 comprising a tread 14 intended to come into contact with a ground during rolling and a crown reinforcement 16 extending in the crown block 12 in the circumferential direction X. The tire 10 also comprises an internal sealing layer 18 to an inflation gas being intended to delimit an internal cavity with a mounting support of the tire 10 once the tire 10 is mounted on the mounting support, for example a rim, this cavity being intended to be pressurized by the inflation gas. The internal sealing layer 18 carries an internal surface 19 of the tire 10. The tire 10 also has an external surface 31.

[0108] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22, each of these reinforcements 20, 22 comprising at least one crown layer. The working reinforcement 16 comprises at least one working layer and here comprises two working layers comprising a radially inner working layer 24 arranged radially inside a radially outer working layer 26.

[0109] The hoop reinforcement 22 comprises at least one hoop layer and comprises here a layer of fretting 28.

[0110] The crown reinforcement 16 is arranged radially inside the tread 14. Here, the hoop reinforcement 22, here the hoop layer 28, is arranged radially outside the working reinforcement 20 and is therefore radially interposed between the working reinforcement 20 and the tread 14.

[0111] The tire 10 comprises two sidewalls 30 extending the crown block 12 radially inwards. The tire 10 further comprises two beads 32 radially inwards to the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown block 12. Each sidewall 30 carries a portion of the external surface 31 of said sidewall 30.

[0112] The tire 10 comprises a carcass reinforcement 34. The crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass layer 36, here a single carcass layer 36, anchored in each bead 32. The carcass layer 36 extends radially in each sidewall 30 and axially in the crown block 12, radially inside the crown reinforcement 16.

[0113] For the purpose of anchoring the carcass layer 36, the tire 10 comprises an axially inner circumferential reinforcing element 38 arranged axially inside the carcass layer 36 and an axially outer circumferential reinforcing element 40 arranged axially outside the carcass layer 36. Here each reinforcing element 38, 40 comprises a continuous wire reinforcing element wound over several circumferential turns, for example as described in WO2021 / 123522.

[0114] The crown reinforcement 16 comprises two axial ends 161, 162 merged here with the ends of the axially widest layer of the crown reinforcement 16. The crown reinforcement 16 comprises a central portion PO of axial width L0 equal to 80% of the axial width L of the crown reinforcement 16, here of the axial width of the hooping layer 28, and axially centered on the median plane M. The crown reinforcement 16 also comprises lateral portions P1, P2 arranged axially on either side of the central portion PO and each having an axial width L1=L2 equal to 10% of the axial width L of the crown reinforcement 16.

[0115] The internal surface 19 does not have, when the tire is inflated to its nominal pressure, an inflection point arranged in line with the crown reinforcement 16, that is to say that the internal surface 19 does not have an inflection point between the axial ends 161, 162.

[0116] Each working layer 24, 26, hooping layer 28 and carcass layer 36 comprises a polymeric matrix, here elastomeric, in which one or more elements of reinforcement of the corresponding layer, here wire reinforcement elements which will be described in particular with reference to figures 1 and 3.

[0117] The hoop reinforcement 22, here the hoop layer 28, is delimited axially by two axial ends 161, 162. The hoop reinforcement 22 comprises one or more hoop wire reinforcement elements 280 wound circumferentially helically so as to extend axially from one axial end to the other of the hoop layer 28 in a main direction DO. The main direction DO forms, with the circumferential direction X of the tire 10, an angle AF, in absolute value, less than or equal to 10°, preferably less than or equal to 7° and more preferably less than or equal to 5°. Here, AF=-5°.

[0118] The radially inner working layer 24 is delimited axially by two axial ends. The radially inner working layer 24 comprises working filamentary reinforcing elements 240 extending axially from one axial end to the other substantially parallel to each other in a main direction D1. Similarly, the radially outer working layer 26 is delimited axially by two axial ends. The radially outer working layer 26 comprises working filamentary reinforcing elements 260 extending axially from the axial end to the other substantially parallel to each other in a main direction D2. Each main direction D1, D2 forms, with the circumferential direction X of the tire 10, angles AT1 and AT2 respectively of opposite orientations.Each main direction D1, D2 forms, with the circumferential direction X of the tire 10, an angle respectively AT1, AT2, in absolute value, strictly greater than 10°, preferably ranging from 15° to 50° and more preferably ranging from 25° to 45°. Here, AT1=-33° and AT2=+33°.

[0119] The carcass layer 36 is delimited axially by two axial ends. The carcass layer 36 comprises carcass wire reinforcement elements 360 extending axially from one axial end to the other of the carcass layer 36 in a main direction D3 forming with the circumferential direction X of the tire 10, an angle AC, in absolute value, greater than or equal to 60°, preferably ranging from 80° to 90° and here AC=+90°.

[0120] Each wire reinforcement element for hooping 280, working 240, 260 and carcass 360 is, for example, identical to those described in application WO2021 / 123522.

[0121] Referring to Figures 1 and 3, the tread 14 comprises a running surface 38 through which the tread 14 contacts the ground.

[0122] The tread 14 comprises several circumferential cutouts, here several circumferential grooves, comprising first, second, third and fourth circumferential cutouts respectively designated by the references 52, 54, 56, 58. Each circumferential cutout 52 to 58 is axially delimited by an axially outer end respectively designated by the reference 521, 541, 561, 581 and by an axially inner end respectively designated by the reference 522, 542, 562, 582. Each circumferential cutout 52 to 58 has a depth respectively designated by the reference Ha1, Ha2, Ha3, Ha4 and ranging from 4.0 mm to the tread height Hs. Each depth Ha1, Ha, Ha3, Ha4 is greater than or equal to 50% of the tread height Hs. Here, Hs=Ha2=Ha3=Ha4=7.5 mm and Ha1=5.0 mm.Each circumferential cutout 52 to 58 has an axial width respectively designated by the reference La1, La2, La3, La4 and greater than or equal to 1.0 mm, preferably greater than or equal to 4.0 mm and more preferably ranging from 4.0 mm to 20.0 mm. Here, La1=7.4 mm and La3=14.4 mm, La2=La4=18.0 mm.

[0123] The tread 14 also comprises several central ribs and here first, second and third central ribs respectively designated by the references 62, 64, 66. Each central rib 62, 64, 66 is arranged axially between two of the adjacent circumferential cutouts 52 to 58 and is delimited axially by two adjacent circumferential cutouts 52 to 58. Each central rib 62, 64, 66 is axially delimited by an axially inner end and by an axially outer end, each axially inner and outer end being an axially inner or outer end of the circumferential cutouts 52 to 58. The axially inner and outer ends of each central rib 62, 64, 66 are adjacent to each other.In this case, the central rib 62 is axially delimited by the axially inner end 522 of the circumferential cutout 52 and by the axially outer end 561 of the circumferential cutout 56. The central rib 64 is axially delimited by the axially inner end 562 of the circumferential cutout 56 and by the axially inner end 582 of the circumferential cutout 58. The central rib 66 is axially delimited by the axially outer end 581 of the circumferential cutout 58 and by the axially inner end 542 of the circumferential cutout 54. Thus, the circumferential cutouts 52, 56 are adjacent to the ribs 62, the circumferential cutouts 56, 58 are adjacent to the rib 64 and the circumferential cutouts 58, 54 are adjacent to the rib 66.Each central rib 62, 64, 66 has a rolling surface intended to come into contact with the substantially flat ground.

[0124] The tread 14 also includes first and second lateral ribs 68, 70.

[0125] Although not visible in Figures 1 and 3, each central rib 62, 64, 66 and each lateral rib 68, 70 includes transverse cutouts formed in each central rib 62, 64, 66 and each lateral rib 68, 70.

[0126] In Figure 3, we have represented: - in dotted lines, the radially outer surfaces SRE passing through the radially outermost points of the radially outermost reinforcing elements 240, 260 and 280 of each crown layer 24, 26, 28, - in dotted lines, the radially inner surfaces SRI passing through the radially innermost points of the radially innermost reinforcing elements 240, 260 and 280 of each crown layer 24, 26, 28, - in dashes, the interfaces of the polymer matrices in which the reinforcing elements of each top layer 24, 26, 28 are embedded.

[0127] With reference to figures 1 and 3, each crown layer, here each working layer 24, 26 and the hooping layer 28, comprises, in the central part PO of the crown reinforcement 16, a plurality of undulations 80 and is therefore said to be undulated. Each corrugation 80 of each corrugated top layer 24, 26, 28 comprises a top 824, 826, 828 respectively of each corrugated top layer 24, 26, 28, first bottoms 844, 846, 848 respectively of each corrugated top layer 24, 26, 28 and second bottoms 844, 846, 848 respectively of each corrugated top layer 24, 26, 28. The tops and bottoms are arranged such that each top 824, 826, 828 is arranged axially between respectively the first and second bottoms 844, the first and second bottoms 846 and the first and second bottoms 848.The vertices and the bottoms are arranged so that each vertex 824, 826, 828 is arranged radially outside respectively the first and second bottoms 844, the first and second bottoms 846 and the first and second bottoms 848. In FIG. 3, in the case where radial distance measurements must be made, the vertices 824, 826, 828 and the bottoms 844, 846, 848 are considered on the radially outer surface SRE of each layer considered.

[0128] Each vertex 824, 826, 828 of each corrugation 80 of each corrugated crown layer 24, 26, 28 is arranged directly above one of the central ribs 62, 64, 66. Each first and second bottom 844, 846, 848 of each corrugation 80 of each corrugated crown layer 24, 26, 28 is arranged directly above each first and second adjacent cutout 52 and 56, 56 and 58, 58 and 54 respectively at each rib 62, 64, 66.

[0129] Each maximum radial amplitude A1, A2, A3 of each corrugation 80 of each corrugated top layer 24, 26, 28 is greater than or equal to 1.0 mm, preferably 1.5 mm and less than or equal to 3.0 mm, preferably 2.5 mm. In this case, each maximum radial amplitude A1, A2, A3 is substantially equal to 2.0 mm.

[0130] Over at least 10%, preferably over at least 20% of the axial width Lf 1 , Lf2, Lf3 of each corrugated crown layer 24, 26, 28 separating each first and second bottom 844, 846, 848 of each corrugation 80, the radial distance between the radially outer surface SRE and the point of the radially outer surface SRE of the bottom 844, 846, 848 radially innermost of one of the first and second bottom 844, 846, 848 of each corrugation 80 is greater than or equal to 1.0 mm, preferably 1.5 mm and less than or equal to 3.0 mm, preferably 2.5 mm. In this case, the radial distance is greater than or equal to 1.5 mm and less than or equal to 2.5 mm over approximately 30% of each axial width Lf 1 , Lf2, Lf3.

[0131] Furthermore, the difference between the minimum radial distance Dmin between, on the one hand, each vertex 828 of each corrugation 80 of the hooping layer 28 and the rolling surface 38, and on the other hand, the depth Ha2, Ha3, Ha4 of each circumferential cutout 54, 56, 58 in line with which each first and second bottom 848 of each corrugation 80 of the hooping layer 28 is arranged is less than or equal to 2 mm.

[0132] The tire comprises two sidewall inserts 90. Each sidewall insert 90 is arranged axially between the outer surface 31 of one of the sidewalls 30 and the inner surface 19 of said sidewall 30. More precisely, each sidewall insert 90 is arranged axially between the inner sealing layer 18 and the axially innermost carcass layer, here the single carcass layer 36. Each sidewall insert 90 has a generally crescent-shaped section.

[0133] Each sidewall insert 90 comprises at least one so-called rigid elastomeric composition. Here, each sidewall insert 90 comprises a rigid elastomeric composition 92 and in this case is made of a rigid elastomeric composition 92. The rigid elastomeric composition 92 of each sidewall insert 90 has a modulus MA10 at 10% extension greater than or equal to 6 MPa and less than or equal to 20 MPa, preferably 15 MPa and more preferably 13 MPa. Here, MA10=8 MPa. In order to formulate this rigid elastomeric composition, it is possible, for example, to use the teaching of WO2014184158, or WO2018111773.

[0134] Each flank insert 90 comprises a radially outer end 94 and a radially inner end 96. Each radially outer end 94 is arranged radially outside the equator E and radially and axially inside of a normal straight line N1 to the internal surface 19 and passing through each axially outer end 161, 162 of the axially widest crown layer of the crown reinforcement 16, here the hooping layer 28. Each radially inner end 96 is arranged radially inside the equator E and radially and axially outside a normal straight line N2 to the internal surface 19 and passing through the radially outer end 33 of the external surface 31 of each bead 32.

[0135] With reference to Figure 2, the thickness of the rigid elastomeric composition 92 and therefore here of the sidewall insert 90 is maximum radially outside the equator E. In this case, the thickness of the rigid elastomeric composition 92 and therefore here of the sidewall insert 90 is maximum between, on the one hand, a radially outer straight line formed by the normal N3 to the internal surface 19 passing through a point 93 of the internal surface 19 arranged 10 mm radially outside a point I and, on the other hand, a radially inner straight line formed by the normal N4 to the internal surface 19 passing through a point 95 of the internal surface 19 arranged 10 mm radially inside this same point I.Point I is the point of each sidewall 30 having a minimum thickness at this point I, the thickness of the sidewall 30 at a point of the internal surface 19 being defined as the straight distance along the normal N to the internal surface 19 at this point of the internal surface 19 between this point of the internal surface 19 and a point of the external surface of the tire aligned along the normal N with this point of the internal surface 19. Here, point 97 is the point of the internal surface 19 at which the thickness of the rigid elastomeric composition 92 and therefore here of the sidewall insert 90 is maximum, this point 97 of the internal surface 19 being arranged radially between the radially external straight line N3 and the radially internal straight line N4. Here, point 97 and point I are substantially coincident so that the maximum thickness Emax is obtained substantially where the thickness of each sidewall 30 is minimum.

[0136] The maximum thickness Emax of the rigid elastomeric composition 92 and therefore here of the sidewall insert 90 is less than or equal to 5.0 mm, preferably ranging from 1.0 to 5.0 mm, more preferably from 1.0 to 3.5 mm and even more preferably from 1.0 to 2.5 mm and very preferably from 1.2 to 1.7 mm. Here, Emax=1.5 mm and the minimum thickness Emin of each sidewall 30 is such that Emin=5.1 mm.

[0137] We will now describe tires according to second and third embodiments of the invention respectively with reference to Figures 4 and 5 in which the elements similar to those shown in the previous figures are designated by identical references.

[0138] Unlike the tire according to the first embodiment, the tire 10 according to the second embodiment of Figure 4 is such that, for the purposes anchoring the carcass layer 36, the tire 10 comprises a circumferential reinforcing element, in this case a bead wire 35 around which the carcass layer 36 is wound so as to form an axially inner portion 361 and an axially outer portion 362 arranged axially outside the axially inner portion 361.

[0139] Unlike the tires according to the first and second embodiments, the carcass reinforcement 34 of the tire 10 according to the third embodiment comprises first and second carcass layers 36, 37 anchored in each bead 32 and extending radially in each sidewall 30 and axially in the crown block 12 radially inside the crown reinforcement 16. The second carcass layer 37 is arranged axially and radially outside the first carcass layer 36. The sidewall insert 90 is arranged axially inside the first carcass layer 36.

[0140] Comparative tests

[0141] The tire 10 according to the first embodiment and in accordance with the invention was compared with a reference tire T1 not in accordance with the invention comprising corrugated crown layers and without a sidewall insert and a control tire T2 not in accordance with the invention comprising corrugated crown layers and a carcass reinforcement comprising first and second carcass layers and without a sidewall insert.

[0142] The 10, T1 and T2 tires were tested to measure their rolling resistance, mass, lateral and drift rigidities, as well as their behavior during a so-called gentle subjective test to assess the behavior of a vehicle equipped with the tires under normal conditions of use, and their subjective behavior during a so-called demanding subjective test to assess the behavior of a vehicle equipped with the tires under representative sporting conditions, particularly those used on a circuit.

[0143] The subjective tests were carried out on the circuit by equipping Ferrari 488 GTB and Porsche Panamera vehicles with the different 10, T1, T2 tires in their corresponding dimensions.

[0144] The results of these tests are given in Table 1 below in which the term “Ref.” indicates a reference value for the corresponding performance.

[0145] [Table 1] ;0146] Table 1 indicates that the tire 10 makes it possible to obtain improved vehicle behavior compared to the reference tire T1. Despite lower dynamic performance than the control tire T2, in particular due to lower lateral rigidities and drifts than the control tire T2, the tire 10 according to the invention nevertheless presents a significantly better compromise than the control tire T2 between behavior, mass and especially manufacturing cost and rolling resistance.

[0147] Concerning the manufacturing cost, the indication “+++” relating to the control tire T2 indicates a cost that is significantly higher than the manufacturing cost of the reference tire T1 and the tire of the invention 10.

[0148] Regarding the mild test, the “+” indication relating to tire 10 indicates reduced understeering behavior and improved high-speed stability compared to the reference tires T1 and control tire T2.

[0149] For the demanding test, the indication "++" for the control tire T2 indicates improved grip stability, improved drift stiffness and improved oversteering behavior compared to the reference tire T1. The indication "+" for tire 10 indicates improved grip stability, improved drift stiffness and slightly improved oversteering behavior compared to the reference tire T1.

[0150] Thus, the invention makes it possible to obtain a tire exhibiting behavior beyond the expected level with a corrugated crown layer.

[0151] The invention is not limited to the embodiments described above.

Claims

DEMANDS 1. A tire (10) not designed for run-flat operation, comprising a crown block (12), two beads (32), and two sidewalls (30) connecting each bead (32) to the crown block (12), the crown block (12) comprising a tread (14) and a crown reinforcement (16) arranged radially within the tread (14), the crown reinforcement (16) comprising a central portion (PO) of axial width (LO) equal to 80% of the axial width (L) of the crown reinforcement (16) and axially centered on the median plane (M) of the tire (10), the crown reinforcement (16) comprising at least one crown layer (24, 26, 28), referred to as corrugated, comprising reinforcing elements embedded in a polymer matrix, said corrugated crown layer (24, 26, 28) comprising, in the central portion (PO) of the top reinforcement (16), at least one undulation (80), the or each undulation (80) of said corrugated top layer (24, 26, 28) comprising a top (824, 826,828) of said undulating top layer and of the first and second bottoms (844, 846, 848) of said undulating top layer adjacent to said top (824, 826, 828) arranged so that:, - said apex (824, 826, 828) is arranged axially between said first and second funds (844, 846, 848), - said apex (824, 826, 828) is arranged radially outside each first and second bottom (844, 846, 848), characterized in that the tire (10) comprises a sidewall insert (90) arranged axially between an external surface (31) of at least one of the sidewalls (30) and an internal surface (19) of said sidewall (30), and in that the sidewall insert (90) comprises at least one rigid elastomeric composition (92), the rigid elastomeric composition or each rigid elastomeric composition (92) of the sidewall insert (90) having a modulus at 10% extension (MA10) greater than or equal to 6 MPa, the maximum thickness (Emax) of the rigid elastomeric composition (92) or of the assembly of rigid elastomeric compositions being less than or equal to 5.0 mm.

2. Tire (10) according to the preceding claim, wherein, the tread (14) comprising at least one rib (62, 64, 66) and first and second cutouts (52, 54, 56, 58) adjacent to the rib, the crest (824, 826, 828) of said corrugation (80) of said corrugated crest layer is arranged vertically below the rib (62, 64, 66) and each first and second bottom (844, 846, 848) of said corrugation (80) of said corrugated crest layer is arranged vertically below each first and second cutout (52, 54, 56, 58) adjacent to the rib (62, 64, 66).

3. A tire (10) according to any one of the preceding claims, wherein the tread (14) comprises a plurality of ribs (62, 64, 66) and a plurality of grooves (52, 54, 56, 58), each rib (62, 64, 66) of the plurality of ribs having first and second grooves (52, 54, 56, 58) adjacent to the plurality of grooves, the corrugated crown layer (24, 26, 28) comprises, in the central part of the crown reinforcement (16), a plurality of corrugations (80), the crest (824, 826, 828) of each corrugation of said corrugated crown layer is arranged vertically below one of the ribs (62, 64, 66), and each first and second bottom of each corrugation of said crown layer corrugated is arranged vertically respectively to each first and second cut (52, 54, 56, 58) adjacent to said rib (62, 64, 66).

4. Pneumatic (10) according to any one of the preceding claims, wherein the modulus at 10% extension (MA10) of the or each rigid elastomeric composition (92) is less than or equal to 20 MPa, preferably to 15 MPa and more preferably to 13 MPa.

5. Pneumatic (10) according to any one of the preceding claims, wherein the maximum thickness (Emax) of the rigid elastomeric composition (92) or of the assembly of rigid elastomeric compositions ranges from 1.0 to 5.0 mm, preferably from 1.0 to 3.5 mm and more preferably from 1.0 to 2.5 mm and even more preferably from 1.2 to 1.7 mm.

6. A tire (10) according to any one of the preceding claims, wherein the sidewall or each sidewall (30) has a minimum thickness (Emin) at a point I, the sidewall thickness at a point on the inner surface (19) being defined as the straight-line distance along the normal (N) to the inner surface (19) from said point on the inner surface (19) to said point on the inner surface (19) between said point on the inner surface (19) and a point on the outer surface (31) of the tire aligned along the normal (N) with said point on the inner surface, the point (97) on the inner surface (19) at which the thickness of the rigid elastomeric composition (92) or of the assembly of rigid elastomeric compositions is maximum is arranged radially between: - a radially external straight line formed by the normal (N3) to the internal surface (19) passing through a point (93) on the internal surface (19) arranged 10 mm radially outside of point I, - a radially interior line formed by the normal (N4) to the internal surface (19) passing through a point (95) of the internal surface (19) arranged 10 mm radially inside the point I.

7. Pneumatic (10) according to any one of the preceding claims, wherein the thickness of the rigid elastomeric composition (92) or of the assembly of rigid elastomeric compositions is maximal radially outside the equator (E) of the tire.

8. Tire (10) according to any one of the preceding claims, wherein the radially outer end (94) of the sidewall insert (90) is arranged radially outside the equator (E) of the tire.

9. Tire according to any one of the preceding claims, wherein the radially inner end (96) of the sidewall insert (90) is arranged radially inside the equator (E) of the tire.

10. Pneumatic (10) according to any one of the preceding claims, comprising a carcass reinforcement (34) comprising at least one carcass layer (36) anchored in the or each bead (32) and extending radially in the or each sidewall (30) and axially in the crown block (12) radially internally to the crown reinforcement (16).

11. Tire (10) according to the preceding claim, comprising an inner sealing layer (18) carrying the inner surface (19) of the tire, the sidewall insert (90) is arranged axially between the inner sealing layer (18) and the innermost axially aligned carcass layer (36).

12. Pneumatic (10) according to claim 10 or 11, wherein the carcass reinforcement (34) comprises a single layer of carcass (36) anchored in the or each bead (32) and extending radially in each sidewall (30) and axially in the top block (12) radially internally to the top reinforcement (16).

13. Pneumatic (10) according to claim 10 or 11, wherein the carcass reinforcement (34) comprises first and second carcass layers (36, 37) anchored in the or each bead (32) and extending radially in each sidewall (30) and axially in the top block (12) radially internally to the top reinforcement (16), the sidewall insert (90) is arranged axially inside the first carcass layer (36).

14. Pneumatic (10) according to any one of the preceding claims, wherein the top reinforcement (16) comprises a working reinforcement (20) comprising at least one working layer (24, 26) and a shrink-fit reinforcement (22) comprising at least one shrink-fit layer (28), the shrink-fit reinforcement (22) being arranged radially outside the working reinforcement (20), the shrink-fit layer or each shrink-fit layer (28) comprising, in the central part (PO) of the top reinforcement (16), at least one corrugation (80).

15. Pneumatic (10) according to the preceding claim, wherein the or each working layer (24, 26) comprises at least one corrugation (80).

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