PNEU CUJA BANDA DE RODAGEM APRESENTA PROPRIEDADES DE RESISTÊNCIA MELHORADAS

Abstract

The invention relates to a tyre in which the tread has at least one cut (8) comprising a radially inner part wider than the radially outer part opening onto the tread surface (6). According to the invention, the tread consists of a first elastomeric compound, and at least part of the wall of said at least one cut (8), surrounding the widened zone, consists of a second elastomeric compound over a thickness (E) of at least 1 mm, the second elastomeric compound having a fatigue strength at least 30% greater than the fatigue strength of the first elastomeric compound, measured at 23°C up to an elongation of 108% in accordance with standard ISO 6943-2017.

Description

1 / 20 A tire with a tread pattern that exhibits improved durability properties.

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

[0002] In general, in tires used on heavy vehicles, the carcass belt is anchored on both sides in the bead area and is radially topped by a crown belt composed of at least two layers, overlapping and formed by parallel wires or cables in each layer and crossed from one layer to the next, forming angles between 10° and 45° with the circumferential direction. Said working layers, which form the working belt, may also be covered with at least one so-called protective layer and formed by advantageously metallic and extensible reinforcing elements, called elastic reinforcing elements.It may also comprise a layer of low-extensibility metallic wires or cables that form an angle between 45° and 90° with the circumferential direction, and this ply, called the triangulation ply, is situated radially between the carcass belt and the first crown ply, called the working ply, formed by parallel wires or cables that present angles of no more than 45° in absolute value. The triangulation ply forms, with at least the said working ply, a triangulated belt that, under the different tensions to which it is subjected, exhibits little deformation, and this triangulation ply has the essential role of absorbing the transverse compression forces to which all the reinforcing elements in the crown area of ​​the tire are subjected.

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

[0004] Cables are said to be elastic when, under a tensile force equal to the breaking load, they exhibit a relative elongation of at least 3% with a maximum tangent modulus of less than 150 GPa. Petition 870250084780, dated 09 / 19 / 2025, p. 16 / 41 2 / 20

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

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

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

[0008] The radial direction is a direction that cuts and is perpendicular to the geometric axis of rotation of the tire.

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

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

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

[0012] Some current tires, known as road tires, are designed to roll at high speeds and on increasingly longer journeys due to the improvement and growth of road networks worldwide. The set of conditions in which such tires are subjected to rolling undoubtedly allows for an increase in the number of kilometers traveled and less tire wear; on the other hand, the tire's resistance, and in particular that of the crown belt, is compromised.

[0013] There are, in fact, stresses within the crown belt and, more particularly, shear stresses between the crown layers, combined with a significant increase in operating temperature at the ends of the axially shorter crown layer, which result in the emergence and propagation of cracks in the rubber at said ends.

[0014] To improve the resistance of the crown belt of the tire type studied, solutions have already been provided regarding the structure and quality of the layers and / or profiles of the rubber compounds arranged between and / or around the edges of the Petition 870250084780, dated 09 / 19 / 2025, p. 17 / 41 3 / 20 plies and, more particularly, the ends of the axially shorter ply.

[0015] In particular, a known artifice consists of introducing a layer of rubber mixture between the ends of the working layers to create a decoupling between said ends to limit shear stresses. However, these decoupling layers must exhibit very good cohesion. Such layers of rubber mixtures are described, for example, in patent application WO 2004 / 076204.

[0016] Tires produced in this way effectively improve performance, especially in terms of durability.

[0017] Furthermore, to manufacture tires with a very wide tread or to give tires of a certain size a greater load capacity, a known technique is to introduce a layer of circumferential reinforcing elements. Patent application WO 99 / 24269, for example, describes the presence of this layer of circumferential reinforcing elements.

[0018] The layer of circumferential reinforcing elements is generally made up of at least one metal cable wound to form a spiral with an installation angle relative to the circumferential direction of less than 2.5°.

[0019] In combination with this internal tire structure, a known technique is to equip the tread, that is, the part of the tire intended to come into contact with the ground during rolling and to suffer wear during rolling, with a pattern formed of raised elements delimited by grooves, whether circumferential, transverse or oblique. The purpose of such a pattern is to give the tread good performance during rolling on dry and wet surfaces, especially in rainy weather.

[0020] To improve the performance of tire treads without excessively reducing their shear stiffness, it is common to create a plurality of edges on the rolling surface with a transverse or oblique orientation to cut through the water film on the road surface and ensure good contact between the tread and the road surface. One way to obtain such edges is to provide the tread with a plurality of cuts, these Petition 870250084780, dated 09 / 19 / 2025, page 18 / 41 4 / 20 cuts have the form of grooves or incisions. In the present application, the incisions are distinguished from the grooves by the fact that the incisions have a width suitable to allow, during rolling, at least partial contact between the opposing walls that delimit these incisions and, specifically, when passing in contact with the ground, which would not be the case for grooves under normal conditions of tire use.

[0021] In addition to the need to improve grip performance through the presence of edges formed by transverse cutouts, it is also necessary that the performance of a tread be durable, that is, satisfactory performance must remain sustainable even after greater or lesser partial wear. Partial tread wear is understood to be a wear condition that corresponds to a tread thickness at most equal to the total tread thickness that can be deteriorated before mandatory tire replacement, mainly for regulatory reasons.

[0022] Patent application WO 02 / 38399-A2 describes a tread pattern for heavy vehicle tires, which has a plurality of circumferential and transverse grooves. The transverse grooves are formed by an alternation of concavities and incisions, thus obtaining a volume of concavities that lead to the rolling surface when new and a volume of hidden concavities, which should open up after partial wear of the tread. The presence of hidden concavities – which appear with wear – results in greater rigidity in the initial state, guaranteeing grip performance for any level of tread wear.

[0023] In the sense of the invention, a cutout with a circumferential or longitudinal orientation is a cutout in which the median plane of at least part of the walls of said cutout forms an angle of less than 10° with a longitudinal plane. This angle formed with the longitudinal plane may be oriented in one direction or another with respect to said longitudinal plane. A cutout with a longitudinal orientation may also be a cutout whose walls undulate or zigzag around Petition 870250084780, dated 09 / 19 / 2025, p. 19 / 41 5 / 20 a medium shot, as already described.

[0024] In the sense of the invention, a transversely oriented cutout is a cutout in which the median plane of at least part of the walls of said cutout forms an angle of less than 35° with the radial plane. This angle formed with a radial plane may be oriented in one direction or another with respect to said radial plane. A transversely oriented cutout may also be a cutout that runs continuously on both sides of a median plane, as described above; it may also be a cutout whose walls undulate or zigzag around a median plane, as just described.

[0025] In the sense of the invention, a cutout with an oblique orientation is a cutout whose median plane of at least part of the walls of said cutout forms an angle between 35° and 80° with a radial plane. This angle formed with a radial plane may be oriented in one direction or another with respect to said radial plane. A cutout with an oblique orientation may also be a cutout that runs continuously on both sides of a median plane, as just described; it may also be a cutout whose walls undulate or zigzag around a median plane, as described.

[0026] During the rolling of tires produced in this way, under particularly demanding stresses on the tread, mainly during rolling with strong skidding and / or on steep slopes, on sidewalks for example, damage to the tread has appeared, which manifests itself, in particular, by the detachment of pieces of rubber.

[0027] In tests, the inventors demonstrated that the presence of certain types of cuts with hidden concavities could impair performance in terms of resistance, resulting in a faster detachment of rubber pieces when compared to similar tires without such hidden concavities for the same use.

[0028] One of the objectives of the invention is to provide tires with improved properties in terms of tread strength, for any use to which they may be put, so that the properties, especially wear and resistance, are improved. Petition 870250084780, dated 09 / 19 / 2025, page 20 / 41 6 / 20 of the tire's overall lifespan should be preserved for normal use.

[0029] This objective is achieved, according to the invention, by a tire with a radial carcass belt comprising a crown belt, itself radially covered with a tread, said tread being joined to two beads by means of two sidewalls. Said tread has a rolling surface intended to come into contact with a track and form a contact surface, said tread having a plurality of cutouts consisting of at least one cutout with a radially inner part wider than the radially outer part leading to the rolling surface, the radially inner part and the radially outer part of said at least one cutout being joined by a widened region.The ratio between the width measured at the bottom of said at least one cut and the width measured on the tread surface of the new tire of said at least one cut is greater than 1.2, wherein the tread is made up of at least one first elastomeric compound forming at least part of the rolling surface when the tire is new, at least part of the wall of said at least one cut, surrounding the widened region, is made up of a second elastomeric compound with a thickness of at least 1 mm, and the second elastomeric compound has a fatigue resistance at least 30% greater than the fatigue resistance of the first elastomeric compound, measured at 23°C up to an elongation of 108% in accordance with ISO 6943-2017.

[0030] The thickness of the second elastomeric mixture is measured locally in a direction orthogonal to the surface of the wall of said at least one circumferential groove.

[0031] The width between the walls of a cutout is measured on the new tire, in a cutting plane perpendicular to the median plane of the walls and to the plane tangent to the tread surface. It is measured in a direction parallel to the plane tangent to the tread surface.

[0032] In the sense of the invention, the width between the walls of a cutout in the tread surface corresponds to the smallest measurement taken on the radially outer part of the cutout and, more precisely, to the smallest measurement taken in Petition 870250084780, dated 09 / 19 / 2025, p. 21 / 41 7 / 20 a region radially comprised between a radially outermost point of said cut and a point located at a distance from the tread surface equivalent to 30% of the depth of said cut.

[0033] In the sense of the invention, the width between the walls of a cutout in the bottom of said cutout corresponds to the largest measurement in the radially inner part of the cutout and, more precisely, to the largest measurement taken in a region radially between the radially innermost point of said cutout and a point located at a distance from the tread surface equivalent to 25% of the depth of said cutout.

[0034] In the sense of the invention, the depth of a cut is the radial distance measured on a new tire between the tread surface and the radially innermost point of said cut.

[0035] As is known, fatigue resistance, expressed in number of cycles or in relative units (ur), is measured on 12 dumbbell-type (H2) specimens subjected to repeated low-frequency tensile forces up to 108% elongation at 23°C, until specimen rupture, according to ISO 6943-2017. During measurement, remanence compensation is required. A higher value indicates better fatigue resistance.

[0036] Preferably according to the invention, the depth, measured on a new tire, of said at least one cut with a radially inner part wider than the radially outer part leading to the rolling surface is greater than or equal to 40% of the tread thickness.

[0037] In the sense of the invention, the tread thickness, measured in a radial cut of the tire, is the distance measured on the new tire between a point on the tread surface and the orthogonal projection of said point onto the radially outer surface of the carcass belt.

[0038] According to a first embodiment of the invention, said at least one cutout is a longitudinally oriented cutout.

[0039] According to a second embodiment of the invention, said at least one cutout is a cross-oriented cutout. Petition 870250084780, dated 09 / 19 / 2025, p. 22 / 41 8 / 20

[0040] According to a third embodiment of the invention, said at least one cutout is an oblique orientation cutout.

[0041] Tires according to the invention manufactured in this manner effectively allow rolling under particularly demanding conditions without tread separation occurring when compared with tires of more conventional design.

[0042] The inventors believe they have demonstrated that, during the rolling of conventionally designed tires under particularly demanding tread conditions, the tread separations that occur appear to originate in the widened region between the visible part of the rolling surface and the hidden part of the groove. The inventors interpret this phenomenon as being due to the extremely small radii of curvature that form, for example, in the region of the groove widening, and that these facilitate the initiation of cracks under the effect of cyclic rolling stresses, especially in the presence of small stones that become trapped. During rolling, under intense tread stresses, particularly during skidding and / or on steep slopes that lead to a transfer of load to the tires further forward on the vehicle, the cracks can propagate and lead to the separation of part of the tread.

[0043] The presence of a mixture according to the invention, at least locally in the area sensitive to the onset of cracks, allows limiting or at least delaying the appearance of cracks and therefore reduces the risk of tread separation, whatever the rolling conditions.

[0044] According to a preferred embodiment of the invention, the entire wall of said at least one cutout is made up of a second elastomeric mixture with a thickness of at least 1 mm, such that the second mixture forms the entire surface of said at least one cutout.

[0045] This preferred embodiment of the invention simplifies the manufacture of the tire according to the invention, where the second mixture is positioned before molding, according to the knowledge of the person skilled in the art, to arrive at the tire according to the invention after burning and molding of the tread forming the Petition 870250084780, dated 09 / 19 / 2025, p. 23 / 41 9 / 20 sculpture.

[0046] According to a preferred embodiment of the invention, the thickness of the second elastomeric mixture is less than 5 mm. The volume of the second mixture therefore remains limited compared to the volume of the first mixture, which contributes primarily to the desired properties for the tread, such as grip and wear.

[0047] According to a preferred embodiment of the invention, the second elastomeric blend has a fatigue resistance at least 50% and more preferably greater than 75% of the fatigue resistance of the first elastomeric blend, measured at 23°C up to an elongation of 108% in accordance with ISO 6943-2017.

[0048] According to an advantageous variant of the invention, the first elastomeric mixture has a maximum tan(δ) value, indicated as tan(δ)max, less than 0.25.

[0049] The loss factor tan(δ) is a dynamic property of the rubber mixture layer. It is measured in a viscoanalyzer (Metravib VA4000), according to ASTM D 5992-96. The response of a vulcanized composition sample (cylindrical specimen 2 mm thick and 78 mm² cross-section), subjected to a simple alternating sinusoidal shear stress, at a frequency of 10 Hz, at a temperature of 60°C, is recorded. A scan is performed in strain amplitude from 0.1 to 50% (forward cycle), and then from 50% to 1% (return cycle). For the return cycle, the maximum observed value of tan(δ), indicated as tan(õ)max, is reported.

[0050] If the material thickness is between 1 and 2 mm, the loss factor tan(δ) is measured by the same method and under the same conditions, as described above, on a vulcanized composition sample in the form of a cylindrical test specimen 1 mm thick and 78 mm2 in cross-section.

[0051] Rolling resistance is the resistance that manifests itself during tire rolling. It is represented by the hysteretic losses linked to the deformation of the tire during a rotation. The frequency values ​​related to tire rotation Petition 870250084780, dated 09 / 19 / 2025, p. 24 / 41 10 / 20 correspond to the tan(δ) values ​​measured between 30 and 100°C. The tan(δ) value at 60°C therefore corresponds to an indicator of the tire's rolling resistance during rolling.

[0052] Furthermore, the tests carried out showed that the rolling resistance properties are preserved, or even improved, by choosing the second elastomeric blend, which can perform even better than the first elastomeric blend with regard to rolling resistance.

[0053] Advantageously, according to the invention, the first elastomeric mixture is a rubber composition based on at least one elastomer matrix containing a styrene-butadiene-based copolymer and at least one reinforcing filler.

[0054] By elastomer matrix or elastomeric matrix, is meant all the elastomer(s) present in the rubber composition.

[0055] A diene elastomer (or indiscriminately rubber), natural or synthetic, should be understood to be an elastomer consisting, at least in part (i.e., a homopolymer or copolymer), of diene monomer(s) (i.e., bearing two carbon-carbon double bonds, conjugated or not).

[0056] By styrene-butadiene copolymer, it is understood here a copolymer of at least one styrene monomer and at least one butadiene monomer (and, of course, any other mixture of such copolymers); in other words, this styrene-butadiene copolymer contains, by definition, at least styrene units (derived from the styrene monomer) and butadiene units (derived from the butadiene monomer).

[0057] Advantageously, according to the invention, the second elastomeric mixture is a rubber composition based on at least one elastomer matrix containing at least 25% of at least one butadiene-based synthetic elastomer and a reinforcing filler.

[0058] According to a preferred embodiment of the invention, the second elastomeric mixture is a rubber composition based on at least one elastomer matrix containing at least 30% and more preferably by Petition 870250084780, dated 09 / 19 / 2025, page 25 / 41 11 / 20 minus 40% of at least one synthetic butadiene-based elastomer.

[0059] Also preferably according to the invention, said at least one synthetic elastomer based on butadiene is an SBR and / or a BR (cis or anionic) and advantageously said at least one synthetic elastomer is a cis BR.

[0060] The rubber compositions according to the invention of the first or second mixture may include one or more reinforcing fillers.

[0061] Any type of reinforcing filler known for its ability to strengthen a rubber compound that can be used specifically for tire manufacturing may be used, for example, an organic filler such as carbon black, an inorganic reinforcing filler such as silica, or a mixture of these two types of filler.

[0062] As examples of carbon blacks, all of them are suitable, especially the carbon blacks conventionally used in tires or their treads. Among the latter, the reinforcing carbon blacks of the 100, 200, 300 series or the carbon blacks of the 500, 600 or 700 series (ASTM D-17652017 grades) are cited, such as, for example, carbon blacks N115, N134, N234, N326, N330, N339, N347, N375, N550, N683, N772.

[0063] Inorganic reinforcing filler is understood here to mean any inorganic or mineral filler, of any color and origin (natural or synthetic), also called white filler, light filler or even non-black filler as opposed to carbon black; this inorganic filler is capable of reinforcing, by itself, without any other means besides an intermediate coupling agent, a rubber composition intended for the manufacture of tires or, in other words, capable of replacing, in its reinforcing function, conventional carbon black qualified for tires. As is known, this filler is generally characterized by the presence of hydroxyl groups (-OH) on its surface, requiring, to be used as a reinforcing filler, the adoption of a coupling agent or system intended to guarantee a stable chemical bond between the filler and the elastomeric matrix.

[0064] As inorganic reinforcing fillers, siliceous mineral fillers are suitable, preferably silica (SiO2). The silica used can be any type of silica. Petition 870250084780, dated 09 / 19 / 2025, page 26 / 41 12 / 20 reinforcement known to those skilled in the art, in particular any precipitated or pyrogenic silica with a BET surface area and a CTAB specific surface area, both less than 450 m2 / g, preferably from 30 to 400 m2 / g, in particular between 60 and 300 m2 / g.

[0065] Naturally, inorganic reinforcing filler also includes mixtures of different inorganic reinforcing fillers, especially highly dispersible silicas such as those described above, or a mixture of siliceous and non-siliceous inorganic fillers. Non-siliceous inorganic fillers include aluminous mineral fillers, especially alumina (Al2O3) or aluminum hydroxides (oxides) or titanium oxides, for example, described in US documents 6,610,261 and 6,747,087. Non-siliceous inorganic fillers, when present, are a minority in the reinforcing filler.

[0066] The physical state of the inorganic reinforcing filler is irrelevant, and it may be in the form of powder, microbeads, granules or beads.

[0067] Those skilled in the art will understand that, as an equivalent filler to the inorganic reinforcing filler described in this paragraph, a reinforcing filler of another nature could be used, in particular an organic filler such as carbon black, provided that this reinforcing filler is coated with an inorganic layer such as silica, or has functional sites on its surface, in particular hydroxyl groups, requiring the use of a coupling agent to establish the bond between the filler and the elastomer. As examples, carbon blacks qualified for tires as described, for example, in patent documents WO 96 / 37547, WO 99 / 28380 are cited.

[0068] According to a variant of the invention, the reinforcing filler of the first and / or second mixture is predominantly carbon black, i.e., it contains more than 50% (>50%) by weight of carbon black relative to the total weight of the reinforcing filler. Optionally, according to this variant, the reinforcing filler may also include silica or another inorganic reinforcing filler.

[0069] According to another variant of the invention, the reinforcing filler of the first and / or second mixture consists of carbon black. Petition 870250084780, dated 09 / 19 / 2025, page 27 / 41 13 / 20

[0070] According to another variant of the invention, the reinforcing filler of the first mixture and / or the second mixture is predominantly an inorganic reinforcing filler (preferably silica), i.e., with more than 50% (>50%) by weight of an inorganic reinforcing filler, such as silica, relative to the total weight of the reinforcing filler. Optionally, in this variant, the reinforcing filler also includes carbon black. In this option, the carbon black is used at a rate less than or equal to 20 phr, more preferably less than or equal to 10 phr (for example, the carbon black rate can vary from 0.5 to 20 phr, in particular from 1 to 10 phr). Within the specified ranges, the coloring (black pigmenting agent) and anti-UV properties of carbon blacks are exploited, without penalizing the typical performance provided by the inorganic reinforcing filler.

[0071] The elastomeric compositions of the tire tread according to the invention may also, as an option, include all or part of the usual additives known to those skilled in the art and commonly used in treads, such as processing aids, fillers (reinforcing or not, in addition to those already mentioned), pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants (6PPD, TMQ), antioxidants, anti-fatigue agents and reinforcing resins (such as those described, for example, in application WO 02 / 10269).

[0072] According to one embodiment of the invention, the tire crown belt is composed of at least two working layers of crown reinforcing elements.

[0073] According to a preferred embodiment of the invention, the reinforcing elements of the crown working layers are inextensible metal cables.

[0074] The metal elements are preferably steel cables.

[0075] Advantageously, according to the invention, the reinforcing elements of the crown strap working layers are crossed from one layer to the next, forming angles between 10° and 45° with the circumferential direction.

[0076] Also advantageously according to the invention, the crown working band comprises a layer of circumferential reinforcing elements, of Petition 870250084780, dated 09 / 19 / 2025, p. 28 / 41 14 / 20 preference arranged radially between two working layers of the crown.

[0077] According to an advantageous embodiment of the invention, the reinforcing elements of at least one layer of circumferential reinforcing elements are metallic reinforcing elements having a secant modulus of 0.7% elongation between 10 and 120 GPa and a maximum tangent modulus of less than 150 GPa.

[0078] A preferred embodiment of the invention further provides that the crown band is radially completed on the outer side by at least one additional layer, called the protective layer, of so-called elastic reinforcing elements, oriented with respect to the circumferential direction at an angle between 10° and 45° and in the same direction as the angle formed by the inextensible elements of the radially adjacent working layer.

[0079] According to any of the embodiments of the invention discussed above, the crown belt can also be completed, radially on the inner side between the carcass belt and the radially inner working layer closest to said carcass belt, by a triangulation layer of inextensible metallic reinforcing elements in steel that form, with the circumferential direction, an angle greater than 45° and in the same direction as the angle formed by the reinforcing elements of the layer radially closest to the carcass belt.

[0080] Other details and advantageous features of the invention will be perceived below from the description of the examples of embodiment of the invention, making reference to Figures 1 to 3 which represent: Figure 1, a meridian view of a tire diagram according to the invention, Figure 2, a projection view of a diagram of a portion of the surface of a tire tread according to the invention, Figure 3, a cross-sectional view along the cutting plane P1 of a longitudinal section of a tire according to the invention. Figure 4, a cross-sectional view along the cutting plane P2 of a cross-sectional cutout of a tire according to the invention.

[0081] The figures are not plotted to scale to facilitate the Petition 870250084780, dated 09 / 19 / 2025, pp. 29 / 41 15 / 20 understanding.

[0082] In Figure 1, tire 1, with dimensions 315 / 70 R 22.5, comprises a radial carcass belt 2 anchored to two beads 3 by a complete turn around the wire bundles 4. The carcass belt is formed from a single layer of metal cables. This carcass belt 2 is tightened by a crown belt 5, formed radially from the inside out: - by a first working layer consisting of non-tightened, continuous, inextensible metal cables 9.35 across the entire width of the canvas, oriented at an angle of 22°, - by a layer of circumferential reinforcing elements formed by 21x23 steel metal cables. - by a second working layer formed by non-tightened, continuous 9.35 inextensible metal cables across the entire width of the canvas, oriented at an angle of 18° and crossed with the metal cables of the first working layer, - by a protective layer formed by 6.35 elastic metal cables.

[0083] All these layers forming the crown belt 5 are not represented in the Figures.

[0084] The crown belt is itself covered with a tread that has a surface 6 intended to come into contact with the ground. The surface 6 of the tread is formed by four circumferential grooves 7 forming circumferential ribs or striations 8 that constitute the tread.

[0085] Figure 2 illustrates a projection view of a diagram of a portion of the surface 6 of a tire tread 1. The surface 6 of the tread is formed by longitudinal cuts 7 and 8 and transverse cuts 9 and 10. The longitudinal cuts 7 and the transverse cuts 9 are grooves, and the longitudinal cuts 8 and the transverse cuts 10 are incisions. The set of these cuts 7, 8, 9 and 10 forms the sculpted elements 11 that constitute the tread.

[0086] Figure 3 schematically represents a longitudinal cut 8 in cross-section along the cutting plane Pi. This cutting plane Pi is perpendicular to the median plane of the walls and to the tangent plane to the surface 6 of the Petition 870250084780, dated 09 / 19 / 2025, pp. 30-41 16 / 20 tread. The width Df of the 8 groove at the bottom of the groove is 6.4 mm. The width ds of the longitudinal groove 8 on the tread surface is measured between the ends 12 and 13 of said longitudinal groove 8 on the tread surface 6. It is 0.8 mm. The ratio Df / ds is 8.

[0087] Figure 4 schematically represents a cross-sectional cutout 10 along the cutting plane P2. This cutting plane P2 is perpendicular to the median plane of the walls and to the plane tangent to the surface 6 of the tread. The width Df' of the cross-sectional cutout 10 at the bottom of the cutout is 4 mm. The width ds' of the cross-sectional cutout 10 of the tread is measured between the ends 14 and 15 of said cross-sectional cutout 10 on the surface 6 of the tread 5. It is 0.6 mm. The ratio Df' / ds' is 6.7.

[0088] In the case of Figures 3 and 4, cutouts 8 and 10 form an incision in the tread surface which, according to the definition given earlier, has a width of less than 2 mm. After tread wear, the concavity hidden under said incision reveals a groove. As discussed earlier, when the tire is new, the incision forms edges, but the tread stiffness remains significant, with the walls coming into contact with each other at the moment of contact with the ground. After wear, when the hidden concavity appears, it forms a groove and, consequently, edges. The loss of stiffness is limited due to the more significant depth of the cutout in the tread.

[0089] The tread is composed mostly of a first mixture. Figures 3 and 4 also represent a thickness E of a second mixture that forms the wall of the circumferential 8 and transverse 10 cutouts.

[0090] The average thickness E of the second mixture is 2 mm. This thickness E is measured in the direction orthogonal to the inner surface of the cutouts 8,10.

[0091] Tests are carried out with the tires according to the invention.

[0092] The same tests are performed with the reference tires. The reference tires differ from the tires according to the invention in that there is no second mixture, i.e., the tread is entirely made up of the first mixture. Petition 870250084780, dated 09 / 19 / 2025, pp. 31-41 17 / 20

[0093] The different mixtures used for tire treads are listed in Table 1 below: TABLE 1 First Mixture Second Mixture NR(1) 60 60 BR (2) 20 40 SBR (3) 20 Carbon black N134 (4) 58 Carbon black N234 (5) 54 Paraffin (6) 1 Antioxidant (6PPD) (7) 2 1.5 Accelerator CBS (8) 1.1 1.1 CTP (9) 0.06 Stearic acid (10) 1.5 1.5 Zinc oxide (11) 2.5 3 Soluble sulfur 1.1 1.1 (1) Natural rubber (2) Neodymium polybutadiene with 98% 1,4-cis unit; Tg=-108°C (3) Styrene-butadiene anionic copolymer containing 15% by weight of styrene unit and 24% vinyl of the butadiene portion (Tg -65°C) (4) Carbon black grade N134 according to ASTM D-1765-2017 (5) Carbon black grade N234 according to ASTM D-1765-2017 (6) SER 6266 from SER (7) N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine Santoflex 6-PPD from Flexsys (8) N-cyclohexyl-2-benzothiazole sulfenamide Santocure CBS from Flexsys Petition 870250084780, dated 09 / 19 / 2025, pp. 32-41 18 / 20 (9) N-cyclohexylthio-phthalimide (CTP / PVI) marketed by Shandong Derek New Materials Co. (10) Pristerene 4931 stearic acid from Uniqema (11) Industrial grade zinc oxide from Umicore

[0094] The component values ​​are expressed in phr (parts by weight per hundred parts of elastomers).

[0095] The measured properties are expressed in Table 2 below for each of the mixtures: TABLE 2 First Mixture Second Mixture Fatigue resistance (ur) 100 177 tan(δ)max (60°C) 0.22 0.17

[0096] The result of fatigue resistance measurements is expressed in relative units (ur). A value higher than the control, arbitrarily set at 100, indicates a better result, i.e., the greater fatigue resistance of the rubber samples.

[0097] Initial endurance tests were carried out on a testing machine that forced each tire to roll in a straight line at a speed equivalent to the maximum speed index prescribed for that tire under an initial load of 4,000 kg, which was gradually increased to reduce the duration of the test.

[0098] Other endurance tests were performed on a testing machine that cyclically imposed a transverse force and a dynamic overload on the tires. The tests were performed on the tires according to the invention under conditions identical to those applied to the reference tires.

[0099] Tests carried out in this manner showed that the distances traveled during each of these tests are at least as long, or even longer, for tires according to the invention than for reference tires.

[00100] A final test was conducted to reproduce a drastic tire skid. It consists of forcing the skid by simulating the limit beyond the Petition 870250084780, dated 09 / 19 / 2025, pp. 33 / 41 19 / 20 which vehicle can roll over.

[00101] This test consists of a preliminary step in which the tire is placed in an oven in a dry environment at 65°C for 15 weeks.

[00102] The tire is driven through the test machine for over 25,000 km at a speed of 40 km / h, with the tire remaining in slippage for approximately 20% of the rolling time. The tire is subjected to a load close to the nominal straight-line load and increased by approximately 40% during slippage. The slippage phases correspond to maximum lateral acceleration before the vehicle rolls over.

[00103] At the end of these tests, the tires are checked by shear interferometry and stripped to analyze any damage. This is a visual analysis that allows comparison of any cracks and their propagation. The tires are marked and compared to each other. A score higher than 100 corresponds to a less damaged tire. A value equal to 100 is assigned to the most damaged reference tire, as per Table 3. TABLE 3 Reference tire, Tire of the invention, Grade 100, Greater than 100

[00104] At the end of the rolling process, the tires according to the invention exhibit less extensive damage than the reference tires.

[00105] In addition, rolling resistance measurements were performed.

[00106] The test results are presented in Table 4 below. Rolling resistance measurements are expressed in kg / t, with a value of 100 assigned to the reference tire. Values ​​above 100 indicate better rolling resistance performance. TABLE 4 Reference tire Tire of the invention Rolling resistance 100 101 Petition 870250084780, dated 09 / 19 / 2025, pp. 34 / 41 20 / 20

[00107] Tests reveal that tires according to the invention allow preserving, and even slightly improving, rolling resistance performance compared to the reference tire. Petition 870250084780, dated 09 / 19 / 2025, pages 35 / 41

Claims

1 / 2 CLAIMS 1. Tire (1) with radial carcass belt (2) comprising a crown belt (5), itself radially covered with a tread, said tread being joined to two beads (3) by means of two sidewalls, said tread comprising a rolling surface (6) intended to contact a track and form a contact surface, said tread having a plurality of cutouts consisting of at least one cutout (8, 10) comprising a radially inner part wider than the radially outer part leading to the rolling surface, the radially inner part and the radially outer part of said at least one cutout being joined by a widened region, the ratio between the width (Df, D'f) measured at the bottom of said at least one cutout (8, 10) and the width (ds, d's) measured on the tread surface of the new tire of said at least one cutout is greater than 1.2,characterized in that the tread is made up of at least one first elastomeric compound forming at least part of the rolling surface (6) when the tire is new, wherein at least part of the sidewall of said tire, or at least one cut (8,10), surrounding the widened region, is made up of a second elastomeric compound with a thickness of at least 1 mm and wherein the second elastomeric compound has a fatigue resistance at least 30% higher than the fatigue resistance of the first elastomeric compound, measured at 23°C up to an elongation of 108% in accordance with ISO 6943-2017.

2. Tire (1), according to claim 1, characterized in that said at least one cutout (8) is a longitudinal orientation cutout.

3. Tire (1), according to claim 1 or 2, characterized in that said at least one cutout (10) is a cross-oriented cutout.

4. Tire (1), according to claim 1 or 2, characterized in that said at least one cutout is an oblique orientation cutout.

5. Tire (1), according to any one of claims 1 to 4, characterized in that the whole wall (10) of said at least one cut (8,10) is made up of the second elastomeric mixture with a thickness of at least 1 Petition 870250084780, dated 19 / 09 / 2025, page 36 / 41 2 / 2 mm.

6. Tire (1), according to any one of claims 1 to 5, characterized in that the thickness of the second elastomeric mixture is less than 5 mm.

7. Tire (1), according to any one of claims 1 to 6, characterized in that the second elastomeric mixture has a fatigue resistance at least 50% greater than the fatigue resistance of the first elastomeric mixture, measured at 23°C up to an elongation of 108% in accordance with ISO 69432017.

8. Tire (1), according to any one of claims 1 to 7, characterized in that the first elastomeric mixture has a maximum value of tan(δ), indicated as tan(δ)max, less than 0.25, the tan(δ) measurement being carried out at 60°C in accordance with ASTM D 5992-96.

9. Tire (1), according to any one of claims 1 to 8, characterized in that the first elastomeric mixture is a rubber composition based on at least one elastomer matrix comprising a styrene-butadiene based copolymer and at least one reinforcing filler.

10. Tire (1), according to any one of claims 1 to 9, characterized in that the first elastomeric mixture is a rubber composition based on at least one elastomer matrix comprising at least 25% of at least one synthetic butadiene-based elastomer and at least one reinforcing filler. Petition 870250084780, dated 19 / 09 / 2025, p. 37 / 41

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