Tire comprising a thin crown and a tread with a convex rib

Abstract

The invention relates to a tire (10) comprising a crown (12) wherein the mean thickness ETm between the working layer (24, 26) is such that ETm ≤ 2.00 mm and wherein the mean radial thickness ECm between the bottom surface (Frd) of the deepest cutout (74, 76) and the hooping reinforcement elements (280) is such that ECm ≤ 2.20 mm, the tire (10) comprising a hooping layer (28) comprising a portion (93), referred to as an indented portion, comprising an undulation (83) having a crest arranged radially in line with an axially central rib (62, 64, 66) and having a radial amplitude (A8) strictly less than 1.00 mm, the tread surface (38) of the axially central rib (62, 64, 66) being radially outwardly convex and having, in a meridian section plane, an amplitude ranging from 0.10 mm to 1.50 mm.

Description

Tire featuring a thin crown and a convex ribbed tread

[0001] The present invention relates to a tire, particularly for passenger vehicles. A tire is defined as a band designed to form a cavity by cooperating with a support element, for example, a rim, this cavity being capable of being pressurized to a pressure greater than atmospheric pressure. A tire according to the invention has a substantially toroidal structure of revolution around a principal axis of the tire.

[0002] We know from the prior art a tire comprising a crown including a tread carrying a tread surface and a crown reinforcement arranged radially inside the tread.

[0003] The tread comprises principal circumferential cuts having a depth greater than or equal to 50% of the tread depth and including first and second axially outer principal circumferential cuts arranged axially on either side of the tire's median plane. The first and second axially outer principal circumferential cuts are the outermost axially outer principal circumferential cuts of the tread. The tread includes an axially central portion of the tread extending from the first axially outer principal circumferential cut to the second axially outer principal circumferential cut.

[0004] The top reinforcement includes a shrink-fit reinforcement comprising a shrink-fit layer comprising shrink-fit reinforcement elements embedded in a polymer shrink-fit matrix.

[0005] The top reinforcement also includes a working reinforcement arranged radially inside the shrinkage reinforcement and comprising a radially outer working layer and a radially inner working layer arranged radially inside the radially outer working layer. Each radially inner and outer working layer respectively comprises radially inner and outer working reinforcement elements embedded respectively in a radially inner and outer working polymer matrix.

[0006] The average thickness ETm of the working reinforcement, in an axially central portion of the apex arranged vertically above the axially central portion of the tread, is between: the radially outer interface between the radially outer working layer and the rest of the tire, and the radially inner interface between the radially inner working layer and the rest of the tire, is such that ETm < 2.00 mm.

[0007] Due to the relatively low ETm value, such a tire therefore has a relatively flexible top.

[0008] In order to reduce tire weight, tire manufacturers have, for some years now, been trying to reduce the thickness of material located under the main circumferential grooves. Thus, on some tires, the average radial thickness ECm is between: - the bottom surface of the deepest cut or cutout in the axially central portion of the tread, and - the radially outer surface passing through the radially outermost points of the most radially outermost reinforcing element(s) among the reinforcing element(s) arranged vertically above the deepest cutout in the axially central portion of the tread, is such that ECm < 2.20 mm.

[0009] Here again, due to the reduced ECm value, such a tire has a relatively flexible top.

[0010] In order to design even lighter tires, the inventors behind the invention combined the characteristics of the two tires described above to obtain a tire in which ETm < 2.00 mm and ECm < 2.20 mm.

[0011] Tests carried out on these tires showed a decrease in tire mass but also a decrease in grip performance on wet surfaces.

[0012] The invention aims to prevent the performance loss of a tire in which ETm < 2.00 mm and ECm < 2.20 mm.

[0013] Furthermore, we know the state of the art of the tires described in WO2018 / 224743A1, JP2013220718A, FR3134344A1.

[0014] To this end, the invention relates to a tire comprising a crown including a tread carrying a tread surface and a crown reinforcement arranged radially inside the tread, the tread comprising principal circumferential cutouts having a depth greater than or equal to 50% of the tread height of the tire comprising first and second principal circumferential cutouts axially external arranged axially on either side of the median plane of the tire, the first and second principal circumferential cutouts axially external being the outermost principal circumferential cutouts of the tread, the tread comprising an axially central portion of the tread extending axially from the first axially outer main circumferential cut to the second axially outer main circumferential cut, the axially central portion of the tread comprising at least one axially central rib carrying at least part of the tread surface, the apex framework comprising: a shrink-fit reinforcement comprising a shrink-fit layer including at least one shrink-fit reinforcement element embedded in a polymer shrink-fit matrix, a working reinforcement arranged radially inside the shrink-fit reinforcement, the working reinforcement comprising at least one working layer including metallic working reinforcement elements embedded in a polymer working matrix, the average thickness ETm, in an axially central portion of the apex arranged vertically above the axially central portion of the tread, between: the radially external interface between the working frame and the rest of the tire, and The radially internal interface between the working frame and the rest of the tire is such that ETm < 2.00 mm. the average radial thickness ECm between: - the bottom surface of the deepest cut or cutout in the axially central portion of the tread, and - the radially external surface passing through the radially outermost points of the most radially external reinforcing element(s) among the reinforcing element(s) arranged vertically above the deepest cut in the axially central portion of the tread, is such that ECm < 2.20 mm, The shrink-fit layer includes, in the axially central portion of the top, a portion, called dented, comprising at least one corrugation, the corrugation or each corrugation of the dented portion of the shrink-fit layer comprising a corrugation top and the first and second corrugation bottoms adjacent to said top arranged such that: - said apex is arranged axially between said first and second bases and directly above the central axial rib, - said apex is arranged radially outside each first and second bottom, the or each corrugation of the dented portion of the shrink-fit layer having a radial amplitude between the apex of the corrugation and the innermost radially located bottom among the first and second bottoms of the corrugation adjacent to said apex strictly less than 1.00 mm, the part of the rolling surface carried by the axially central rib being radially convex outwards and having, in a meridian cutting plane, an amplitude ranging from 0.10 mm to 1.50 mm.

[0015] The tire according to the invention allows, in addition to the mass savings obtained thanks to the reduced ETm and ECm values, improved performance in terms of grip on wet surfaces.

[0016] Indeed, the inventors of the invention understood that the decrease in wet grip performance described earlier was a consequence of a change in the tire's contact patch. Specifically, the inventors noted that the axially central rib had concave ends, as shown in Figure 1, whereas, conversely, the contact patch of a tire with good performance has straight or convex rib ends.

[0017] The inventors also understood that a contact area in which the axially central rib had concave ends was the consequence, on the one hand, of the presence of a corrugation in the top and, on the other hand, of a bending of the rolling surface of the axially central rib.

[0018] The waviness is due to the relatively low ECm value. Indeed, current extrusion processes during tread manufacturing do not allow for a constant distance between: - the surface parallel to the rolling surface passing through the bottom surface of the main circumferential cutouts, and - the radially outer surface passing through the radially outermost points of the radially outermost reinforcement element(s) of the reinforcement element(s) on the axial width of the tread.

[0019] In particular, directly above the main circumferential grooves, this distance is extremely small and difficult to control industrially. Therefore, to obtain a tread that is usable industrially, it has a greater average thickness directly above the main circumferential grooves than above each axially central rib. This difference in thickness, combined with the low average thickness, results in waviness during the tire curing process.

[0020] The curvature of the tread surface of the axially central rib stems from the relatively low value of ETm. Indeed, after the tire has cured, due to a higher thermal shrinkage coefficient of the tread material(s) compared to the thermal shrinkage coefficient of the metal reinforcement elements, the tread surface of the axially central rib will contract more axially than the radially inner portion of the axially central rib, which is held axially by the embedded metal reinforcement elements. This difference in axial contraction generates the curvature of the tread surface of the axially central rib.

[0021] Once these two causes were identified, the inventors discovered that by applying a radially outward curved tread surface directly above the crest of the corrugation in the dented section, the effects of the corrugation and bending on the axially central rib were compensated for. This prevented a degradation of the tire's wet grip performance, in addition to the weight reduction achieved through lower ETm and ECm values.

[0022] Unexpectedly, the invention also improved rudder rigidity performance. Indeed, correcting the tire's contact area allows for a more even distribution of pressure on the central rib, which is beneficial to rudder rigidity.

[0023] The determination of the average radial thickness ECm is done in the axially central portion of the top by measuring, between the surfaces, several axially distributed radial thicknesses between the bottom surface of the or each deepest cut made in the axially central portion of the tread and the radially outer surface passing through the radially outermost points of the most radially outermost reinforcing element(s) among the reinforcing element(s) arranged in line with the corresponding deepest cut(s).

[0024] These measurements will be taken in several equally spaced meridional cross-sectional planes around the circumference of the tire, for example, in four meridional cross-sectional planes. The radial thicknesses thus measured will then be averaged to obtain the average radial thickness ECm.

[0025] Radial thickness between two surfaces is understood to be the straight thickness between a point on one of the surfaces and its projection onto the other surface along the radial direction of the tire.

[0026] The thickness between two surfaces is defined as the smallest distance between them. Thus, the thickness of a layer is the distance measured along a direction normal to the two surfaces delimiting that layer.

[0027] By portion arranged in line with the axially central portion of the tread, we mean the portion whose axial ends coincide with the axial ends of the axially central portion of the tread.

[0028] Each axially central portion of the tread and crown comprises the median plane of the tire.

[0029] The determination of the average thickness ETm is done in a manner analogous to that of the average radial thickness ECm described above.

[0030] Each radially external and internal interface used to determine the average thickness ETm is an interface between two different polymer matrices. These radially external and internal interfaces are generally visible due to the difference between the polymer matrix(s) of the crown reinforcement and the polymer matrix(s) of the rest of the tire. Implicitly, each radially external and internal interface is the interface between the working reinforcement and the radially external and internal polymer matrices, respectively, adjacent to and in contact with the working reinforcement.

[0031] The rib is said to be axially central because of its belonging to the axially central portion of the tread, which may include one or more axially central ribs regardless of their position in the axially central portion of the tread.

[0032] An axially central rib can have a constant or variable axial width. In either case, the axially central rib has two axial ends that determine its maximum axial width. The amplitude of the outwardly convex radial running surface is determined as the radial distance between a first straight line passing through the intersections of: extensions of the lateral walls of the circumferential cutouts delimiting the axially central rib, and the bearing surface of the axially central rib, and a second line parallel to the first line and passing through the outermost radial point of the axially central rib surface.

[0033] A rib is a raised section of the tread in the radial direction, as opposed to a cut, which is recessed in the radial direction. Because they are delimited by at least one main circumferential cut, each rib extends substantially circumferentially. A rib can be continuous circumferentially or discontinuous circumferentially, interrupted by cuts. We distinguish between axially central ribs, delimited axially by two adjacent main circumferential cuts, and axially lateral ribs, delimited axially by one of the first and second axially outermost main circumferential cuts and by one of the axial edges of the tread surface. Each axially lateral rib is therefore the outermost axial rib of the tread on each side of the tire's median plane.

[0034] The radially outwardly curved running surface has a generally convex shape. The running surface may be symmetrical about the median plane of the axially central rib, with the median plane of the axially central rib being equidistant from each axial end, thus determining the maximum axial width of the axially central rib. Alternatively, the running surface may be asymmetrical about the median plane of the axially central rib.

[0035] By "fields adjacent to a vertex," we understand that no other field is axially arranged between the vertex and each adjacent field.

[0036] Unless the dented portion of the bracing layer describes a polygonal line comprising straight segments in each meridional cutting plane, each corrugation includes two inflection points arranged axially between the crest and each first and second bottom. An inflection point is defined as a point where, in a meridional cutting plane, the direction of curvature of the dented portion of the bracing layer changes.

[0037] The amplitude of a corrugation is measured between the crest of said corrugation and the innermost radially flattened bottom of the first and second bottoms of said corrugation adjacent to said crest. The crest and the first and second bottoms are considered on the radially outer surface of the shrink-fit layer, the radially outer surface being the surface passing through the outermost radially flattened points of the outermost radially flattened reinforcement elements of the shrink-fit layer.

[0038] Conventionally, the tread surface is axially delimited by first and second axial edges that coincide with the first and second axial edges of the tread, respectively. The first and second axial edges are determined on a tire mounted on a nominal rim and inflated to the nominal pressure as defined in the ETRTO 2024 standard manual. The first and second axial edges are positioned on either side of the tire's median plane and are formed by lines substantially parallel to the tire's circumferential direction. In the case of a clear boundary between the tread surface and the rest of the tire, the first and second axial edges are determined simply.In the case where the tread surface is continuous with the external surfaces of the sidewalls of the tire, the first and second axial edges are usually determined by loading the tire to 80% of its load capacity according to the ETRTO 2024 standard manual and the first and second axial edges are identified as the axial limits of the tread in contact with the ground.

[0039] A matrix is ​​said to be polymeric because it is based on a polymeric composition, this polymeric composition being able to include one or more polymers, for example chosen from thermoplastic polymers, thermosetting polymers, elastomers, thermoplastic elastomers, but also fillers and other components usually used in the field of tire compositions, in particular compositions for embedding reinforcement elements.

[0040] Preferably, the polymer matrix is ​​an elastomeric matrix. An elastomeric matrix is ​​defined as a matrix exhibiting elastomeric behavior in the crosslinked state. Such a matrix is ​​advantageously obtained by crosslinking a composition comprising at least one elastomer and at least one other component. Preferably, the composition comprising at least one elastomer and at least one other component includes an elastomer, a crosslinking system, and a filler. The compositions used for these layers are conventional compositions for calendering reinforcements, typically based on natural rubber or another diene elastomer, a reinforcing filler such as carbon black, a vulcanizing system, and standard additives.The adhesion between the wire reinforcement elements and the matrix in which they are embedded is ensured for example by a standard adhesive composition, for example an RFL type glue or equivalent glue such as for example described in W02013017421 or W02017168109.

[0041] A reinforcing element is defined as an element that provides mechanical reinforcement to the polymer matrix in which it is embedded. Preferably, each reinforcing element is wire-like, meaning that each element has a length at least 10 times greater than the longest dimension of its cross-section, regardless of the cross-section's shape: circular, elliptical, oblong, polygonal, and in particular rectangular, square, or oval. In the case of a rectangular cross-section, the wire-like reinforcing element is in the form of a strip.

[0042] A cutout or a portion of a cutout has two main characteristic dimensions: a width and a curvilinear length such that the curvilinear length is at least twice the width. A cutout or a portion of a cutout is therefore delimited by at least two main lateral faces determining its curvilinear length and connected by a base, the two main lateral faces being separated from each other by a non-zero distance, called the width of the cutout or portion of the cutout.

[0043] The principal direction of a cut is the direction along which the curve equidistant from each edge of the cut to the radial dimension of the running surface passes. The curvilinear length is the length measured along this curve equidistant from each edge of the cut to the radial dimension of the running surface, between each end of the cut. The mean direction is the shortest curve joining the two ends of the cut.

[0044] The width of a cut or portion of a cut is, in the case where the cut or portion of a cut does not include a chamfer, on a new tire, the distance between the two main sidewalls measured over the entire depth of the cut or portion. The width of a cut or portion of a cut is, in the case where the cut or portion of a cut includes a chamfer, on a new tire, the distance between the two main sidewalls measured over the entire depth of the cut or portion radially inside the chamfer. The width is measured substantially perpendicular to the main sidewalls. The minimum width of a cut or portion is the smallest width of the cut or portion in question.

[0045] The depth of a cut or portion of a cut on a new tire is the radial distance between the bottom of the cut or portion and its projection onto the ground during tire rolling. The maximum depth of a cut or portion is the greatest of the depths of the cut or portion in question.

[0046] The maximum depth of the cuts is called the tread depth. Preferably, the maximum depth of the main circumferential cuts is called the tread depth. Thus, preferably, the deepest cut in the axially central portion of the tread is a main circumferential cut.

[0047] A cutout or a portion of a cutout can be transverse or circumferential.

[0048] A cut or cross-section is such that the cut extends along an average direction forming an angle strictly greater than 30°, preferably greater than or equal to 45°, with the circumferential direction of the tire, i.e., forming an angle less than or equal to 60°, preferably strictly less than 45°, with the axial direction of the tire. A cut or cross-section may be continuous, i.e., not interrupted by a tread block or another cut, so that the two principal lateral faces determining its length are uninterrupted along the length of the cross-section or cross-section.A cut or a cross-section may also be discontinuous, that is, interrupted by one or more blocks of sculpture and / or one or more cutouts so that the two main lateral faces determining its length are interrupted by one or more blocks of sculpture and / or one or more cutouts.

[0049] A cut or circumferential portion is such that the cut or portion extends along an average direction forming an angle of 30° or less, preferably 10° or less, with the circumferential direction of the tire, i.e., forming an angle strictly greater than 60°, preferably strictly greater than 80°, with the axial direction of the tire. In the case of a continuous circumferential cut, the two ends coincide and are joined by a curve making a complete rotation of the tire. A cut or circumferential portion can be continuous, i.e., not interrupted by a tread block or another cut, so that the two principal lateral faces determining its length are uninterrupted over the entire circumference of the tire.A circumferential cut can also be discontinuous, that is, interrupted by one or more tread blocks and / or one or more cuts so 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 whole of one turn of the tire.

[0050] The tire according to the invention has a substantially toroidal shape around an axis of revolution substantially coinciding 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.

[0051] Axial direction refers to the direction substantially parallel to the axis of revolution of the tire, that is, the axis of rotation of the tire.

[0052] By circumferential direction, we mean the direction which is substantially perpendicular to both the axial direction and to a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[0053] By radial direction, we mean 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.

[0054] By median plane of the tire (denoted M), we mean the plane perpendicular to the axis of rotation of the tire which is located at mid-axial distance of the two ribs and passes through the axial midpoint of the crown reinforcement.

[0055] The circumferential equatorial plane of a tire, in a meridional cross-section, is defined as the plane passing through the tire's equator, perpendicular to the median plane and the radial direction. The tire's equator, in a meridional cross-section (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), is the axis parallel to the tire's axis of rotation and located equidistant between the outermost radial point of the tread intended to be in contact with the ground and the innermost radial point of the tire intended to be in contact with a support, such as a rim.

[0056] By meridian plane, we mean a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0057] Radially inside and radially outside refer to the area closest to and further from the tire's axis of rotation, respectively. Axially inside and axially outside refer to the area closer to and further from the tire's median plane, respectively.

[0058] The bead is the portion of the tire designed to allow the tire to be attached to a mounting surface, such as a wheel with a rim. Each bead is specifically designed to make contact with a hook on the rim, enabling it to be secured.

[0059] Any range of values ​​designated by the expression "between a and b" represents the range of values ​​from more than a to less than b (i.e., bounds a and b excluded) while any range of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict bounds a and b).

[0060] Any angle made between two directions is the smallest of the angles made by those two directions with each other.

[0061] In preferred embodiments of the invention, the tires are intended for passenger vehicles as defined in the European Tyre and Rim Technical Organisation (ETRTO) standard, 2024. Such a tire has a cross-section in a meridional plane characterized by a section height H and a nominal section width or sidewall size S, as defined in the European Tyre and Rim Technical Organisation (ETRTO) standard, 2024, such that the H / S ratio, expressed as a percentage, is at most 90 and at least 20, and the nominal section width S is at least 115 mm and at most 385 mm. Furthermore, the hook diameter D, defining the diameter of the tire's mounting rim, is at least 12 inches and at most 30 inches.

[0062] In preferred embodiments of the invention, the tires are summer tires. By summer, we mean tires that are neither all-season or four-season tires, nor winter tires.

[0063] Winter tires are identified by the M+S marking (M+S stands for "Mud + Snow") and / or the 3PMSF marking (3PMSF stands for "3 Peak Mountain Snow Flake"). All-season tires, due to their performance on snow, also display the M+S and / or 3PMSF markings. Summer tires, however, do not have the M+S or 3PMSF markings.

[0064] In advantageous and optional embodiments, each metal working reinforcement element comprises a single metal monofilament.

[0065] The use of metallic monofilaments allows for a further reduction in tire mass by decreasing the average thickness ETm and the mass of the metallic reinforcement elements. The invention therefore enables the use of metallic monofilaments while improving tire performance, particularly drift stiffness and wet grip.

[0066] Examples of such metallic monofilaments are described in WO2015 / 014574, WO2015 / 014575, WO2015 / 014576, WO2015 / 014577, WO2016 / 124417, WO2019 / 020886, WO2019 / 020887, WO2019 / 020888.

[0067] In advantageous and optional embodiments, each metallic monofilament has a diameter ranging from 0.28 mm to 0.42 mm, preferably from 0.30 mm to 0.40 mm.

[0068] A diameter that is too small would reduce the tire's load-bearing capacity and therefore its performance. A diameter that is too large would lead to excessive mass. A diameter as described above allows for a sufficient reduction in mass and, thanks to the invention, compensates for the reduction in average thickness ETm.

[0069] In embodiments using two working layers, the working reinforcement comprises a radially outer working layer and a radially inner working layer arranged radially inside the radially outer working layer, each radially inner and outer working layer comprising respectively radially inner and outer metallic working reinforcement elements embedded respectively in a radially inner and outer polymer working matrix.

[0070] Advantageously, in embodiments using two working layers, the average thickness ET1m, in the axially central portion of the vertex, between: the radial interface between the radially outer working layer and the radially inner working layer, and the radially inner interface between the radially inner working layer and the rest of the tire, is such that ET1 m < 1.00 mm, preferably ET1 m < 0.95 mm and more preferably ET1m < 0.90 mm.

[0071] Advantageously, in embodiments using two working layers, the average thickness ET2m, in the axially central portion of the vertex, between: the radially outer interface between the radially outer working layer and the rest of the tire, and the radial interface between the radially outer working layer and the radially inner working layer, is such that ET2m < 1.00 mm, preferably ET2m < 0.95 mm and more preferably ET2m < 0.90 mm.

[0072] Thus, in some embodiments, only one of the two values ​​ET1m, ET2m is such that ETim < 1.00 mm, preferably ETim < 0.95 mm and more preferably ETim < 0.90 mm, i being equal to 1 or 2. In other embodiments, the two values ​​ET1m, ET2m are such that ET1m < 1.00 mm and ET2m < 1.00 mm, preferably ET1m < 0.95 mm and ET2m < 0.95 mm and more preferably ET1m < 0.90 mm and ET2m < 0.90 mm.

[0073] For the same reasons as those described above, such average radial thicknesses ET1m and ET2m allow for a significant reduction in mass, the effect of which on tire performance, particularly drift stiffness and wet grip, can be compensated for by the invention.

[0074] In other embodiments in which the working reinforcement comprises a single working layer, the average thickness ETm, in an axially central portion of the top arranged vertically above the axially central portion of the tread, between: the radially outer interface between the working layer and the rest of the tire, and the radially inner interface between the working layer and the rest of the tire, is such that ETm < 1.10 mm, preferably ETm < 1.00 mm, more preferably ETm < 0.95 mm and even more preferably ETm < 0.90 mm.

[0075] Such an average thickness ETm allows for a significant reduction in mass, the effect of which on tire performance, particularly drift stiffness and wet grip, can be compensated for by the invention. In these embodiments, the single working layer is, for example, like those described in W02022008807, W02021074511, WO2016166057, or EP3489035.

[0076] In these embodiments using a single working layer, each metallic working reinforcement element comprises an assembly of several metallic monofilaments. Each metallic monofilament optionally has a diameter strictly less than 0.32 mm, preferably less than or equal to 0.30 mm.

[0077] In advantageous and optional embodiments, ECm < 2.10 mm, preferably ECm < 2.00 mm, more preferably ECm < 1.90 mm, even more preferably ECm < 1.70 mm, very preferably ECm < 1.50 mm and most preferably ECm < 1.30 mm.

[0078] Using an even lower average radial thickness (ECm) allows for a further reduction in tire mass. The invention therefore enables the use of a very low average radial thickness (ECm) while improving tire performance, particularly drift stiffness and wet grip.

[0079] In advantageous and optional embodiments allowing characterization of the undulation or each undulation, the undulation or each undulation of the dented portion has a radial amplitude between 0.50 mm and 1.00 mm.

[0080] In advantageous and optional embodiments allowing the convex surface to be characterized, the part of the rolling surface carried by the axially central rib has, in a meridian cutting plane, an amplitude ranging from 0.25 mm to 0.75 mm, preferably from 0.30 mm to 0.75 mm and even more preferably from 0.35 mm to 0.75 mm.

[0081] In advantageous and optional embodiments for characterizing the effects of the corrugation and distinguishing it from intentional corrugations of amplitude greater than or equal to 1.00 mm applied exclusively to the crown reinforcement, in particular to the shrink-fit reinforcement and the working reinforcement, the tire comprises a carcass reinforcement comprising a carcass layer comprising, in the axially central portion of the crown, a portion, called dented, comprising at least one corrugation, the corrugation or each corrugation of the dented portion of the carcass layer comprising a crest of the corrugation and the first and second bottoms of the corrugation adjacent to said crest arranged such that: - said apex is arranged axially between said first and second bottoms and vertically above the axially central rib, - said apex is arranged radially outside each first and second bottom, the or each undulation of the dented portion of the carcass layer having a radial amplitude between the apex of the undulation and the innermost radially inner bottom among the first and second bottoms of the undulation adjacent to said apex strictly less than 1.00 mm, preferably between 0.50 mm and 1.00 mm.

[0082] In optional and advantageous embodiments, in the axially central portion of the apex, the shrink-fitting reinforcement element(s) forming several circumferential windings, the circumferential windings are arranged axially next to each other without radial overlap with respect to each other.

[0083] In embodiments, the axially central portion of the tread comprising several central ribs delimited axially by the main axially internal and external circumferential cutouts, the dented portion comprising several undulations, the apex of each undulation being arranged vertically below one of the central ribs.

[0084] In advantageous and optional embodiments, the axially central portion of the tread comprises several axially central ribs, each axially central rib comprising a tread surface convex radially outwards and having, in a meridian cutting plane, an amplitude ranging from 0.10 mm to 1.50 mm.

[0085] In preferred variants of these embodiments, the axially central rib or ribs are axially delimited by an axially internal main circumferential cutout and an axially external main circumferential cutout.

[0086] In embodiments in which the main circumferential cutouts are relatively deep, each main circumferential cutout has a depth ranging from 4.0 mm to the carving height, preferably ranging from 5.0 mm to the carving height and more preferably ranging from 5.5 mm to the carving height.

[0087] In embodiments in which the main circumferential cutouts are relatively deep, each main circumferential cutout has a depth greater than or equal to 75% of the sculpture height, preferably 90% of the sculpture height.

[0088] In embodiments in which the main circumferential cutouts are adapted to summer passenger vehicle tires, each main circumferential cutout has a minimum width greater than or equal to 3.0 mm, preferably greater than or equal to 5.0 mm and more preferably ranging from 5.0 mm to 20.0 mm.

[0089] In embodiments adapted for summer passenger vehicle tires, the axially central rib or ribs have a maximum width greater than or equal to 15.0 mm, preferably greater than or equal to 20.0 mm and more preferably ranging from 20.0 mm to 40.0 mm.

[0090] In embodiments adapted for summer passenger car tires, the axially central rib or ribs are devoid of transverse cutouts, or the axially central rib or ribs comprise transverse cutouts having a maximum width of 5.0 mm or less, preferably 3.0 mm and more preferably 2.0 mm. Even more preferably, in the axially central rib or ribs, at least 75% of all the transverse cutouts have a maximum width of 5.0 mm or less, preferably 3.0 mm and more preferably 2.0 mm.

[0091] In some embodiments, the tread comprises a tread layer intended to come into contact with a road surface and a radially inner layer at least partially separate from the tread layer. Such a radially inner layer allows for the optimization of certain tire performance characteristics, for example, rolling resistance, wet grip, and handling.

[0092] In a first configuration of these embodiments, the radially inner layer may be designed to avoid contact with the ground during tire rolling, at least until a regulatory wear threshold is reached. This radially inner layer will be referred to as the support layer.

[0093] In a second configuration of these embodiments, the radially inner layer can be designed to come into contact with the ground during tire rolling before the tire reaches the regulatory wear threshold. This radially inner layer is referred to as the worn tread layer, as opposed to the new tread layer, which is the outermost radially layer and is designed to be in contact with the ground when the tire is new.

[0094] In other variations, the tread does not include an inner radial layer. Thus, the tread consists solely of a surface layer intended to come into contact with the road surface, which is in direct contact with the tire's crown reinforcement.

[0095] In some embodiments, a tread may be used comprising a tread layer intended to come into contact with a running surface comprising a single elastomeric material.

[0096] In other embodiments, a tread may be used comprising a wearing course intended to come into contact with a running surface comprising several different elastomeric materials depending on the axial direction, for example such as those described in applications filed under numbers PCT / EP2025 / 054345, PCT / EP2025 / 054330 or PCT / EP2025 / 054338 or published under number W02025 / 002600.

[0097] Conventionally, a tire comprises a crown, two sidewalls, and two beads, with each sidewall connecting each bead to the crown. The tire also includes a carcass reinforcement anchored in each bead and extending radially into each sidewall and axially into the crown, radially internal to the crown reinforcement.

[0098] In embodiments enabling the achievement of radial tire performance, for example as defined by ETRTO, the carcass reinforcement comprises at least one carcass layer, each layer comprising wire carcass reinforcement elements, each wire carcass reinforcement element extending substantially along a principal direction forming an angle, in absolute value, of 80° to 90° with the circumferential direction of the tire. Alternatively, particularly in embodiments using a single working layer, a variable angle of 80° to 90° may be used in at least a portion of the sidewall and strictly less than 80° in at least a portion of the crown, as described, for example, in LIS20190152262.

[0099] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the drawings in which: Figure 1 is a view of an imprint of a contact area of ​​a test tire not conforming to the invention, exhibiting reduced ETm and ECm values; Figure 2 is a view, in a meridian cross-sectional plane, of a tire according to a first embodiment of the invention. Figures 3 and 4 are detailed views of an axially central portion of the apex of the tire in Figure 1. Figures 5 and 6 are views analogous to that of figure 3 of tires according to second and third embodiments, and Figure 7 is a view similar to that of Figure 1 of a tire according to the invention.

[0100] In the figures relating to the tire, we have represented a coordinate system X, Y, Z corresponding to the usual directions respectively axial (Y), radial (Z) and circumferential (X) of a tire.

[0101] Figures 2 to 4 show a tire according to the invention, designated by the general reference numeral 10. The tire 10 has a substantially toroidal 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 / 50R18 104H XL. In the various figures, the tire 10 is shown in its new condition, i.e., having not yet been driven on.

[0102] The tire 10 includes a crown 12 comprising a tread 14 intended to come into contact with a ground during rolling and a crown reinforcement 16 extending into the crown 12 in the circumferential direction X. The tire 10 also includes an internal sealing layer 18 for an inflation gas intended to delimit an internal cavity with a mounting support for 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.

[0103] The top reinforcement 16 comprises a working reinforcement 20 and a restraining reinforcement 22, each of these reinforcements 20, 22 comprising at least one top layer. The working reinforcement 16 comprises at least one working layer and here comprises two working layers, including a radially inner working layer 24 arranged radially inside a radially outer working layer 26. The innermost radially top layer of the top reinforcement 16 is here the radially inner working layer 24.

[0104] The shrink frame 22 includes at least one shrink layer and here includes a shrink layer 28.

[0105] The top reinforcement 16 is arranged radially inside the tread 14. Here, the working reinforcement 20 is arranged radially inside the shrink-fit reinforcement 22. The shrink-fit reinforcement 22 is therefore radially interposed between the working reinforcement 20 and the tread 14.

[0106] The tire 10 comprises two sidewalls 30 extending radially inwards from the apex 12. The tire 10 further comprises two beads 32 radially inwards from the sidewalls 30. Each sidewall 30 connects each bead 32 to the apex 12.

[0107] The tire 10 includes a carcass reinforcement 34. The crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 includes a layer 36 of carcass anchored in each bead 32 and extending radially in each sidewall 30 and axially in the crown 12 radially internally to the crown reinforcement 16.

[0108] For the purpose of anchoring the carcass layer 36, the tire 10 includes circumferential reinforcing elements 37, here beads. Alternatively, reinforcing elements and anchoring such as those described in WO2021 / 123522 may be considered.

[0109] With reference to Figure 3, each radially inner and outer working layer 24, 26, shrinkage layer 28 and carcass layer 36 comprises a polymeric matrix, here elastomeric, respectively radially inner and outer working layer, shrinkage layer and carcass layer in which are embedded one or more reinforcing elements of the corresponding layer, here wire reinforcing elements.

[0110] The shrink-fitting reinforcement 22, here the shrink-fitting layer 28, comprises one or more wire shrink-fitting reinforcement elements 280 circumferentially helically wound so as to extend axially from one axial end to the other of the shrink-fitting layer 28 in a principal direction forming, with the circumferential direction X of the tire 10, 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° and here equal to 1°.

[0111] The radially inner working layer 24 comprises radially inner working wire reinforcement elements 240 extending axially from one axial end of the radially inner working layer 24 to the other, substantially parallel to each other along a first principal direction. Similarly, the radially outer working layer 26 comprises radially outer working wire reinforcement elements 260 extending axially from one axial end of the radially outer working layer 26 to the other, substantially parallel to each other along a second principal direction. Each first and second principal direction forms opposite angles with the circumferential direction X of the tire 10.Each first and second principal direction forms, with the circumferential direction X of the tire 10, an angle, in absolute value, strictly greater than 10°, preferably ranging from 15° to 50° and more preferably ranging from 20° to 40° and here equal to 27°.

[0112] The carcass layer 36 comprises wire carcass reinforcement elements 360 extending axially from one axial end to the other of the carcass layer 36 in a principal direction forming with the circumferential direction X of the tire 10, an angle, in absolute value, greater than or equal to 60°, preferably ranging from 80° to 90° and here equal to 90°.

[0113] Each wire reinforcement element 280 for the frame and 360 for the frame is, for example, identical to those described in application WO2021 / 123522. Other variants are permitted, particularly with regard to the wire reinforcement elements for the frame 360, which may include elements made of rayon, aramid, polyester, or combinations thereof. Each radially internal working wire reinforcement element 240 and external wire reinforcement element 260 comprises a single metal monofilament with a diameter ranging from 0.28 mm to 0.42 mm, preferably from 0.30 mm to 0.40 mm, and in this case, 0.32 mm.

[0114] The tread 14 has a tread surface 38 through which the tread 14 comes into contact with the ground. The tread surface is axially delimited by first and second axial edges E1, E2 coinciding respectively with the first and second axial edges E1, E2 of the tread 14.

[0115] The tread 14 comprises several main circumferential cutouts 70, 72, 74, 76 including first and second main circumferential axially external cutouts 70, 72 arranged axially on either side of the median plane M of the tire 10. The first and second main circumferential axially external cutouts 70, 72 are the outermost main circumferential axial cutouts of the tread 14.

[0116] Each circumferential cutout 70 to 76 has a depth, designated by reference Ha, ranging from 4.0 mm to the carving height Hs, preferably from 5.0 mm to the carving height Hs, and more preferably from 5.5 mm to the carving height Hs. Each depth Ha is greater than or equal to 50% of the carving height Hs, preferably 75% of the carving height, and more preferably 90% of the carving height. Here, Hs = 7.0 mm, the depth Ha of each circumferential cutout 74, 76 is equal to 7.0 mm, and the depth Ha of each circumferential cutout 70, 72 is equal to 6.5 mm. Each main circumferential cutout 70 to 76 has a minimum width La greater than or equal to 3.0 mm, preferably greater than or equal to 5.0 mm and more preferably ranging from 5.0 mm to 20.0 mm.

[0117] The tread 14 comprises an axially central portion POb extending axially from the first axially external main circumferential cutout 70 to the second axially external main circumferential cutout 72. The axially central portion POb of the tread comprises several axially central ribs 62, 64, 66. The tread 14 also comprises first and second axially lateral portions P1b, P2b, each comprising an axially lateral rib 67, 69, respectively. Each axially central rib 62, 64, 66 is axially delimited by axially internal and external main circumferential cutouts 70 and 74, 74 and 76, and 76 and 72, respectively. Each axially central rib 62, 64, 66 has a maximum width greater than or equal to 15.0 mm, preferably greater than or equal to 20.0 mm and more preferably ranging from 20.0 mm to 40.0 mm.

[0118] Although not visible in Figures 2 and 3, each axially central rib 62, 64, 66 and each axially lateral rib 67, 69 includes transverse cutouts formed in each axially central rib 62, 64, 66, at least 75% of which have a maximum width of 5.0 mm or less, preferably 3.0 mm, and more preferably 2.0 mm. Each axially lateral rib 67, 69 also includes transverse cutouts formed in each axially lateral central rib 67, 69, the maximum width of which may exceed 3.0 mm.

[0119] Figure 3 shows: - in dotted lines, the radially external surfaces 100, 102, 104, 106 passing through the radially outermost points respectively of the most radially external carcass reinforcement elements 360, working elements 240, 260 and shrinkage elements 280 of the carcass layer 36, of each radially internal and external working layer 24, 26 and shrinkage layer 28, - in dotted lines, the radially internal surfaces 105, 107, 109 passing through the radially innermost points respectively of the most radially internal working reinforcement elements 240, 260 and of the most radially internal confinement elements 280 of each radially internal and external working layer 24, 26 and of confinement elements 28, - in dashes, the interfaces 124, 126, 128 of the polymer matrices in which the working reinforcement elements 240, 260 of each radially inner and outer working layer 24, 26 are embedded.

[0120] With reference to figures 2 to 4, the carcass layer 36, each radially inner and outer working layer 24, 26 and the shrink-fit layer 28, comprises, in an axially central portion POs of the top 12 arranged vertically above the axially central portion POb of the tread 14, respectively a portion 90, 91, 92, 93 comprising respectively several undulations 80, 81, 82, 83 and is therefore said to be dented.

[0121] In the axially central portion POs of the top 12, the 280 shrink-fitting reinforcement element(s) forming several circumferential windings, the circumferential windings are arranged axially next to each other without radial overlap with respect to each other.

[0122] For obvious reasons of clarity of figure 3, we will describe each undulation 80, 81, 82, 83 of the dented portion 90, 91, 92, 93 of the carcass layer 36, each radially inner and outer working layer 24, 26 and of the shrink layer 28 with reference to the undulation 80, 81, 82, 83 intersecting the median plane M of the tire. Each wave 80, 81, 82, 83 includes a vertex 822, 824, 826, 828 respectively of each wave 80, 81, 82, 83, of the first backgrounds 842, 844, 846, 848 respectively of each wave 80, 81, 82, 83 and of the second backgrounds 843, 845, 847, 849 respectively of each wave 80, 81, 82, 83. The first backgrounds 842, 844, 846, 848 and second backgrounds 843, 845, 847, 849 are adjacent respectively to each vertex 822, 824, 826, 828.The vertices and bases are arranged so that each vertex 822, 824, 826, 828 is axially arranged between the first 842 and second 843 bases, the first 844 and second 845 bases, the first 846 and second 847 bases, and the first 848 and second 849 bases, respectively. The vertices and bases are arranged so that each vertex 822, 824, 826, 828 is radially arranged outside the first 842 and second 843 bases, the first 844 and second 845 bases, the first 846 and second 847 bases, and the first 848 and second 849 bases, respectively. We consider the vertices 822, 824, 826, 828 and the first and second bottoms 842, 844, 846, 848, 843, 845, 847, 849 on the radially outer surface 100, 102, 104, 106 of each layer considered.

[0123] Each vertex 822, 824, 826, 828 of each corrugation 80, 81, 82, 83 of the dented portion 90, 91, 92, 93 of the carcass layer 36, of each radially inner and outer working layer 24, 26, and of the reinforcement layer 28 is arranged vertically above the axially central rib 64. Each first bottom 842, 844, 846, 848 and second bottom 843, 845, 847, 849 of each corrugation 80, 81, 82, 83 of the dented portion 90, 91, 92, 93 of the carcass layer 36, of each radially inner and outer working layer 24, 26, and of the reinforcement layer 28 is arranged in line respectively with each main circumferential cutout 74, 76 adjacent to said axially central rib 64.

[0124] Each undulation 80, 81, 82, 83 of the dented portion 90, 91, 92, 93 of the working layer 36, of each radially inner and outer working layer 24, 26, and of the shrink-fit layer 28 has respectively a radial amplitude A2, A4, A6, A8 between each crest 822, 824, 826, 828 of said undulation 80, 81, 82, 83 and the innermost radially deepest of the first deepest 842, 844, 846, 848 and second deepest 843, 845, 847, 849 of said undulation 80, 81, 82, 83 adjacent to said crest 822, 824, 826, 828. Each radial amplitude A2, A4, A6, A8 is strictly less than 1.00 mm, preferably between 0.50 mm and 1.00 mm. In this case, A1=A2=A3=0.75 mm.

[0125] Figure 3 also shows the bottom surfaces Frd of the main circumferential cuts 74, 76 deepest made in the axially central portion POb.

[0126] The average radial thickness ECm between the base surfaces Frd and the radially outer surface 106 arranged directly above each deepest cut 74, 76 in the axially central portion POb of the tread 14 is such that ECm < 2.20 mm, preferably ECm < 2.10 mm, more preferably ECm < 2.00 mm, even more preferably ECm < 1.90 mm, and most preferably ECm < 1.70 mm. Furthermore, ECm > 0.50 mm, preferably ECm > 1.00 mm. In this case, ECm = 1.70 mm. Alternatively, ECm < 1.50 mm, most preferably ECm < 1.30 mm, could be considered.

[0127] Figure 3 also shows: the radially internal interface 124 between the working reinforcement 20 and the rest of the tire, here between the radially internal working layer 24 and the carcass layer 36, the radial interface 126 between the radially outer working layer 26 and the radially inner working layer 24, and the radially external interface 128 between the working reinforcement 20 and the rest of the tire, here between the radially external working layer 26 and the shrink-fit layer 28.

[0128] The average thickness ETm, in the axially central portion POs of the vertex 12, between the radially external interface 128 and the radially internal interface 124, is such that ETm < 2.00 mm.

[0129] The average thickness ET1m, in the axially central portion POs of the top 12 arranged vertically above the axially central portion POb of the tread 14, between the radial interface 126 and the radially inner interface 124 is such that ET1m < 1.00 mm, preferably ET1m < 0.95 mm and more preferably ET1m < 0.90 mm.

[0130] The average thickness ET2m, in the axially central portion POs of the apex 12 arranged vertically above the axially central portion POb of the tread 14, between the outer radial interface 128 and the radial interface 126, is such that ET2m < 1.00 mm, preferably ET2m < 0.95 mm, and more preferably ET2m < 0.90 mm. Here, ET1m = ET2m = 0.83 mm.

[0131] With reference to Figure 4, the part of the rolling surface 38 carried by each axially central rib 62, 64, 66 is radially convex outwards and has, in a meridian cutting plane, an amplitude A ranging from 0.10 mm to 1.50 mm, preferably from 0.25 mm to 0.75 mm, preferably from 0.30 mm to 0.75 mm and even more preferably from 0.35 mm to 0.75 mm and here equal to 0.6 mm.

[0132] With reference to figure 4, in order to determine the amplitude A of each axially central rib 62, 64, 66, we determine a first straight line D1 passing through the intersections: extensions of the lateral walls Fr of the circumferential cutouts 70 to 76 delimiting each axially central rib 62, 64, 66, and the rolling surface 38 of each axially central rib 62, 64, 66.

[0133] We determine a second line D2 parallel to the first line D1 and passing through the outermost radial point of the surface 38 of each axially central rib 62, 64, 66.

[0134] We will now describe a tire according to second and third embodiments of the invention with reference respectively to Figure 5 and Figure 6 on which elements similar to those shown in the previous figures are designated by identical references.

[0135] Unlike the tire in the first embodiment, the working reinforcement 20 of the tire 10 in the second embodiment shown in Figure 5 comprises a single working layer 25 including metallic working reinforcement elements 250 embedded in a polymer working matrix. Each metallic working reinforcement element 250 comprises an assembly of two metallic monofilaments, each having a diameter strictly less than 0.32 mm, and in this case, 0.30 mm. Alternatively, metallic monofilaments as described in the first embodiment may be used.

[0136] The pneumatic system according to the second embodiment uses an architecture as described in W02022008807, W02021074511, WO2016166057 or EP3489035 or US20190152262.

[0137] The working layer 25 comprises, in its axially central portion POs, a portion 95 comprising a plurality of undulations 85 and is therefore said to be dented. Each undulation 85 of the dented portion 95 of the working layer 25 comprises a crest 827 and first and second bottoms 847, 849 of the undulation 85. Each undulation 85 of the dented portion 95 of the working layer 25 has a radial amplitude A5 between each crest 827 of said undulation 85 and the innermost radial bottom among the first and second bottoms 847, 849 of said undulation 85 adjacent to said crest 827. The radial amplitude A5 is strictly less than 1.00 mm, preferably between 0.5 mm and 1.00 mm, and here equal to 0.75 mm.

[0138] The average thickness ETm, in the axially central portion POs, between: the radially external interface 130 between the working layer 25 and the rest of the tire, here between the working layer 25 and the shrink-fit layer 28, and the radially internal interface 132 between the working layer 25 and the rest of the tire, here between the working layer 25 and the carcass layer 36, is such that ETm < 1.10 mm, preferably ETm < 1.00 mm, more preferably ETm < 0.95 mm and even more preferably ETm < 0.90 mm.

[0139] Unlike the tire according to the first embodiment, the carcass reinforcement 34 of the tire 10 according to the third embodiment of Figure 6 does not include a dented portion.

[0140] Comparative tests

[0141] We compared the tire 10 according to the first embodiment and in accordance with the invention and a control tire T not in accordance with the invention whose contact area imprint is shown in figure 1.

[0142] The T test tire is identical to the 10 tire except that its axially central ribs do not have a radially outward curved tread surface.

[0143] We tested the 10 and T tires to measure drift rigidity on a measuring machine and to evaluate grip on wet ground through a subjective test carried out on a circuit coated with a film of water by equipping a BMW 6 Series vehicle with these different tires.

[0144] The results of these tests are given in Table 1 on a scale of 100, which corresponds to the performance of the reference tire T. A value greater than 100 indicates improved performance. A value less than 100 indicates degraded performance.

[0145] [Table 1] T 10 Drift stiffness 100 102.6 Wet grip 100 100.7

[0146] Table 1 indicates that the invention significantly improves drift rigidity and wet grip performance. An improvement in the contact patch of tire 10, illustrated in Figure 7, is also observed compared to the contact patch of the control tire T, illustrated in Figure 1.

[0147] The invention is not limited to the embodiments described above.

[0148] It may also be expected that the tread will include noise reduction devices, including Helmoltz resonators as described for example in EP0989000, EP2011671, EP2240335, EP2627524.

[0149] It may also be provided that the tire includes a noise reduction device as described in WO2022 / 069822 or as described in EP1219944, EP1253025, EP1184207, EP1110763, EP1876038.

[0150] Elastomeric compositions such as those described in EP3012118 may be provided. In addition, all or part of the tread may be provided for to be based on an elastomeric composition comprising between 0.5 pc and 6 pc of antioxidant agent, for example 6-PPD.

Claims

1. - 27 - DEMANDS 1. Tire (10) comprising a crown (12) comprising a tread (14) carrying a tread surface (38) and a crown reinforcement (16) arranged radially inside the tread (14), the tread (14) comprising principal circumferential cutouts (70, 72, 74, 76) having a depth (Ha) greater than or equal to 50% of the tread height (Hs) of the tire (10) comprising first and second axially external principal circumferential cutouts (70, 72) arranged axially on either side of the median plane (M) of the tire (10), the first and second axially external principal circumferential cutouts (70, 72) being the outermost axially external principal circumferential cutouts of the tread (14), the tread (14) comprising an axially central portion (POb) of the tread (14) extending axially from the first axially external principal circumferential cutout (70) to the second axially external principal circumferential cutout (72),the axially central portion (POb) of the tread (14) comprising at least one axially central rib (62, 64, 66) carrying at least part of the tread surface (38), the apex reinforcement (16) comprising: a shrink-fit reinforcement (22) comprising a shrink-fit layer (28) comprising at least one shrink-fit reinforcement element (280) embedded in a polymer shrink-fit matrix, a working reinforcement (20) arranged radially inside the shrink-fit reinforcement (22), the working reinforcement (20) comprising at least one working layer (24, 26; 25) comprising metallic working reinforcement elements (240, 260; 250) embedded in a polymer working matrix, the average thickness ETm, in an axially central portion (POs) of the apex (12) arranged vertically above the axially central portion (POb) of the tread (14), between: the radially external interface (128; 130) between the working frame (20) and the rest of the tire, and the radially internal interface (124; 132) between the working frame (20) and the rest of the tire, is such that ETm < 2.00 mm, characterized in that the average radial thickness ECm between: - the bottom surface (Frd) of the deepest cut (74, 76) formed in the axially central portion (POb) of the tread (14), and - the radially outer surface (106) passing through the radially outermost points of the most radially outermost reinforcing element(s) (280) among the reinforcing element(s) (280) arranged vertically above the deepest cut (74, 76) made in the axially central portion (POb) of the tread (14), is such that ECm < 2.20 mm, in that the bracing layer (28) comprises, in the axially central portion (POs) of the top (12), a portion (93), said to be dented, comprising at least one corrugation (83), the or each corrugation (83) of the dented portion (93) of the bracing layer (28) comprising a top (828) of the corrugation (83) and the first (848) and second bottoms (849) of the corrugation adjacent to said top (828) arranged such that: - said apex (828) is arranged axially between said first (848) and second bottoms (849) and vertically above the axially central rib (62, 64, 66), - said vertex (828) is arranged radially outside each first (848) and second bottom (849), the or each undulation (83) of the dented portion (93) of the shrink-fit layer (28) having a radial amplitude (A8) between the crest (828) of the undulation (83) and the innermost radially deepest of the first (848) and second deepest (849) of the undulation (83) adjacent to said crest (828) strictly less than 1.00 mm, and in that the part of the rolling surface (38) carried by the axially central rib (62, 64, 66) is radially convex outwards and has, in a meridian cutting plane, an amplitude (A) ranging from 0.10 mm to 1.50 mm.

2. Pneumatic (10) according to the preceding claim, wherein each metallic working reinforcement element (240, 260) comprises a single metallic monofilament.

3. Pneumatic (10) according to the preceding claim, wherein each metallic monofilament has a diameter ranging from 0.28 mm to 0.42 mm, preferably from 0.30 mm to 0.40 mm.

4. Pneumatic (10) according to any one of the preceding claims, wherein the working reinforcement (20) comprises a radially outer working layer (26) and a radially inner working layer (24) arranged radially within the radially outer working layer (26), each radially inner (24) and outer (26) working layer comprising, respectively, radially inner (240) and outer (260) metallic working reinforcement elements embedded, respectively, in a radially inner and outer polymeric working matrix.

5. Pneumatic (10) according to the preceding claim, wherein the average thickness ET1m, in the axially central portion (POs) of the apex (12), is between: the radial interface (126) between the radially outer working layer (26) and the radially inner working layer (24), and the radially inner interface (124) between the radially inner working layer (24) and the rest of the tire, is such that ET1m < 1.00 mm, preferably ET1m < 0.95 mm and more preferably ET1m < 0.90 mm.

6. Pneumatic (10) according to claim 4 or 5, wherein the average thickness ET2m, in the axially central portion (POs) of the apex (12), is between: the radially outer interface (128) between the radially outer working layer (26) and the rest of the tire, and the radial interface (126) between the radially outer working layer (26) and the radially inner working layer (24), is such that ET2m < 1.00 mm, preferably ET2m < 0.95 mm and more preferably ET2m < 0.90 mm.

7. Pneumatic (10) according to any one of the preceding claims, wherein ECm < 2.10 mm, preferably ECm < 2.00 mm, more preferably ECm < 1.90 mm, even more preferably ECm < 1.70 mm, most preferably ECm < 1.50 mm and most preferably ECm < 1.30 mm.

8. Pneumatic (10) according to any one of the preceding claims, wherein the undulation or each undulation (83) of the dented portion (93) has a radial amplitude (A8) between 0.50 mm and 1.00 mm.

9. Pneumatic (10) according to any one of the preceding claims, wherein the part of the rolling surface (38) carried by the axially central rib (62, 64, 66) has, in a meridian cutting plane, an amplitude (A) ranging from 0.25 mm to 0.75 mm, preferably from 0.30 mm to 0.75 mm and even more preferably from 0.35 mm to 0.75 mm.

10. Pneumatic (10) according to any one of the preceding claims, comprising a carcass frame (34) comprising a carcass layer (36), the carcass layer (36) comprising, in the axially central portion (POs) of the crest (12), a portion (90), said to be dented, comprising at least one corrugation (80), the or each corrugation (80) of the dented portion (90) of the carcass layer (36) comprising a crest (822) of the corrugation (80) and the first (842) and second bottoms (843) of the corrugation adjacent to said crest (822) arranged such that:- said crest (822) is arranged axially between said first (842) and second bottoms (843) and vertically above the axially central rib (62, 64, 66), - said vertex (822) is arranged radially outside each first (842) and second bottom (843), the or each undulation (80) of the dented portion (90) of the carcass layer (36) having a radial amplitude (A2) between the crest (822) of the undulation (80) and the innermost radially deep bottom among the first (842) and second bottoms (843) of the undulation (80) adjacent to said crest (822) strictly less than 1.00 mm, preferably between 0.50 mm and 1.00 mm.

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