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 groove on the bottom of which at least one protuberance is integrally formed. According to the invention, the tread consists of a first elastomeric blend, and at least part of the bottom of said at least one groove surrounding the junction zones between said at least one protuberance and the bottom of said at least one groove consists of a second elastomeric blend over a thickness of at least 1 mm, the second elastomeric blend having a fatigue strength at least 30% greater than the fatigue strength of the first elastomeric blend, measured at 23°C up to an elongation of 108% in accordance with standard ISO 6943-2017.

Description

1 / 18 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 triangulation, 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 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 870250082245, dated 12 / 09 / 2025, p. 16 / 39 2 / 18

[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 870250082245, dated 12 / 09 / 2025, p. 17 / 39 3 / 18 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 cutouts, whether oriented in a circumferential, transverse or oblique direction. The objective of such a pattern is to give the tread good performance during rolling on dry and wet surfaces, especially in rainy weather.

[0020] In the sense of the invention, a cutout generally designates a groove or an incision and corresponds to the space delimited by walls of the material opposite and separated from each other by a distance other than zero (called the width of the cutout). What differentiates an incision from a groove is precisely this distance; in the case of an incision, this distance is adequate to allow at least partial contact of the opposite walls that delimit said incision, at least to Petition 870250082245, dated 12 / 09 / 2025, page 18 / 39 4 / 18 pass in contact with the track. In the case of a groove, the walls of that groove cannot come into contact with each other under normal rolling conditions.

[0021] 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 a 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 a median plane, as already described.

[0022] In the sense of the invention, a cutout with a transverse 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 35° 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 a transverse orientation 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.

[0023] 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.

[0024] In the case of grooves, it is common to provide for the presence of indentations at the bottom of these grooves. Indentations are protrusions made of the material whose height is less than the depth of the groove. They can have different functions. They can be designed to provide rigidity, offering support for the groove walls. Petition 870250082245, dated 12 / 09 / 2025, page 19 / 39 5 / 18 when these undergo deformation during rolling. Furthermore, they can be designed to allow the ejection of stones that obstruct the grooves during rolling.

[0025] During the rolling of tires produced in this way, under particularly demanding stresses on the tread, especially during rolling with very intense slippage and / or steep slopes, damage to the tread has occurred, which manifests itself, in particular, by the detachment of pieces of rubber.

[0026] 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 are put, so that the properties, especially wear and overall tire strength, are preserved for normal use.

[0027] 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 contact a track and form a contact surface, said tread having a plurality of cuts consisting of at least one groove composed of two walls leading to the rolling surface and a surface joining the two walls forming the bottom of said at least one groove, said at least one protrusion made of the material being present at the bottom of said at least one groove, and the height of said protrusion being greater than 10% of the depth of said at least one groove and less than the height of said at least one groove.The width of said protrusion, measured in a direction orthogonal to the walls of said at least one groove, is greater than or equal to 40% of the width of said at least one groove, measured in a direction orthogonal to the walls of said at least one groove, and less than that width of said at least one groove, and said protrusion is joined to the bottom of said at least one groove by junction areas, wherein the tread is made up of at least one first elastomeric compound forming at least part of the rolling surface. Petition 870250082245, dated 12 / 09 / 2025, page 20 / 39 6 / 18 when the tire is new, at least part of the bottom of said at least one groove surrounding the junction areas between said at least one protrusion and the bottom of said at least one groove is made 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.

[0028] In the sense of the invention, the depth of a groove is the radial distance measured on a new tire between the tread surface and the innermost radial point of said groove.

[0029] In the sense of the invention, the height of a protrusion present at the bottom of a groove is the radial distance measured on a new tire between the outermost radial point of said protrusion and the innermost radial point of said groove.

[0030] In the sense of the invention, the widths of the protrusions and grooves are measured in a direction orthogonal to the groove walls in new tires.

[0031] 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.

[0032] 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, in accordance with ISO 6943-2017. During measurement, remanence compensation is required. A higher value indicates better fatigue resistance.

[0033] According to a first embodiment of the invention, said at least one groove is a longitudinally oriented groove.

[0034] According to a second embodiment of the invention, said at least one groove is a transverse orientation groove.

[0035] According to a third embodiment of the invention, said at least one groove is an obliquely oriented groove. Petition 870250082245, dated 12 / 09 / 2025, page 21 / 39 7 / 18

[0036] 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.

[0037] The inventors believe they have demonstrated that, during the rolling of conventionally designed tires under particularly demanding tread conditions, tread separation appears to originate in the junction areas between a protrusion and the bottom of a groove. The inventors interpret this phenomenon as being due to the extremely small radii of curvature that form, for example, in these junction areas, and which promote 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 load transfer to the tires further forward on the vehicle, the cracks propagate and can lead to the separation of part of the tread.

[0038] The presence of a mixture according to the invention, at least locally in the area susceptible to cracking, allows limiting or at least delaying the appearance of these cracks and therefore reduces the risk of tread separation, whatever the rolling conditions.

[0039] According to a preferred embodiment of the invention, the bottom and walls of said at least one groove consist 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 groove.

[0040] 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 design.

[0041] According to a preferred embodiment of the invention, the thickness of Petition 870250082245, dated 12 / 09 / 2025, page 22 / 39 8 / 18 The second elastomeric compound is less than 5 mm, not taking into account the volume of the protrusion that may be formed from this second compound. The volume of the second compound remains limited, therefore, compared to the volume of the first compound, which mainly contributes to the desired properties for the tread, such as grip and wear.

[0042] According to a variant embodiment of the invention, said at least one protrusion present in said at least one groove is continuous along the length of said groove. In the case of a circumferential groove, said protrusion is continuous around the circumference of the tire.

[0043] According to another embodiment of the tire, said at least one protrusion present in said at least one groove is discontinuous along the length of said groove. In this embodiment, the protrusion advantageously creates a pattern that repeats along the length of the groove to ensure its function along the length of the groove.

[0044] According to a preferred embodiment of the invention, the second elastomeric blend has a fatigue resistance at least 50% greater and, more preferably, 75% greater than the fatigue resistance of the first elastomeric blend, measured at 23°C up to an elongation of 108% in accordance with ISO 6943-2017.

[0045] According to an advantageous variant of the invention, the first elastomeric mixture has a maximum value of tan(õ)max, indicated as tan(õ)max, less than 0.25.

[0046] The loss factor tan(õ) 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 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^), indicated as tan(õ)max, is reported. Petition 870250082245, dated 12 / 09 / 2025, p. 23 / 39 9 / 18

[0047] If the material thickness is between 1 and 2 mm, the loss factor tan^) 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.

[0048] 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 correspond to the tan(õ) values ​​measured between 30 and 100°C. The tan(õ) value at 60°C therefore corresponds to an indicator of the tire's rolling resistance during rolling.

[0049] 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.

[0050] 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.

[0051] By elastomer matrix or elastomeric matrix, is meant all the elastomer(s) present in the rubber composition.

[0052] 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).

[0053] A styrene-butadiene copolymer is understood here to be 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 units of Petition 870250082245, dated 12 / 09 / 2025, page 24 / 39 10 / 18 butadiene (derivatives of the butadiene monomer).

[0054] 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 synthetic butadiene-based elastomer and at least one reinforcing filler.

[0055] 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, at least 40% of at least one synthetic butadiene-based elastomer.

[0056] Preferably, and 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.

[0057] Rubber compositions according to the invention of the first or second mixture may include one or more reinforcing fillers.

[0058] Any type of reinforcing filler known for its ability to strengthen a rubber compound suitable for use, in particular 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.

[0059] 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.

[0060] 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 Petition 870250082245, dated 12 / 09 / 2025, page 25 / 39 11 / 18 rubber compound 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 the adoption of a coupling agent or system designed to ensure a stable chemical bond between the filler and the elastomeric matrix to be used.

[0061] As inorganic reinforcing fillers, siliceous mineral fillers are suitable, preferably silica (SiO2). The silica used may be any reinforcing silica 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.

[0062] 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 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.

[0063] The physical state of the inorganic reinforcing filler is irrelevant, and it may be in the form of powder, microbeads, granules or beads.

[0064] 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 Petition 870250082245, dated 12 / 09 / 2025, page 26 / 39 12 / 18 99 / 28380.

[0065] 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.

[0066] According to another variant of the invention, the reinforcing filler of the first and / or second mixture consists of carbon black.

[0067] 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.

[0068] 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).

[0069] According to one embodiment of the invention, the tire crown belt is composed of at least two working layers of crown reinforcing elements. Petition 870250082245, dated 12 / 09 / 2025, p. 27 / 39 13 / 18

[0070] According to a preferred embodiment of the invention, the reinforcing elements of the crown working layers are inextensible metal cables.

[0071] The metal elements are preferably steel cables.

[0072] 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.

[0073] Also advantageously according to the invention, the crown working band comprises a layer of circumferential reinforcing elements, preferably arranged radially between two crown working layers.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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 and 2 which represent: Figure 1, a meridian view of a tire diagram according to Petition 870250082245, dated 12 / 09 / 2025, p. 28 / 39 14 / 18 the invention, Figure 2, a radial cross-sectional view of a tire groove according to the invention.

[0078] The figures are not plotted to scale for ease of understanding.

[0079] 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 9.35 mm inextensible, non-tightened metal cables, continuous across the entire width of the canvas, oriented at a 22° angle, - by a layer of circumferential reinforcement elements 43 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.

[0080] All these layers forming the crown belt 5 are not represented in the Figures.

[0081] 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. At the bottom of the circumferential grooves 7 are represented the indentations 9. These indentations 9 are continuous around the wheel. According to other embodiments, they could be discontinuous; they could also not be present in all grooves.

[0082] Figure 2 schematically represents a circumferential groove 7 in Petition 870250082245, dated 12 / 09 / 2025, pp. 29 / 39 15 / 18 cross section along a radial plane, making an indentation 9 appear in the material at the bottom of said groove 7.

[0083] The circumferential groove 7 has a depth d7 of 14.5 mm. The indentation 9 has a height d9 of 11.5 mm. The indentation 9 therefore has a height d9 equivalent to 79% of the depth d7 of the circumferential groove 7 and therefore greater than 10%. The circumferential groove 7 has a width d7 of 15.2 mm. The indentation 9 has a width d9 of 8.7 mm. The indentation 9 therefore has a width d9 equivalent to 57% of the width d7 of the circumferential groove 7 and therefore greater than 40%.

[0084] The tread is composed mainly of a first compound. Figure 2 also represents a thickness E of a second compound forming the wall 10 of the circumferential groove 7.

[0085] 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 circumferential groove 7.

[0086] Tests are carried out with the tires according to the invention.

[0087] 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.

[0088] The different compounds used for tire treads are listed below: 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 Petition 870250082245, dated 12 / 09 / 2025, pp. 30 / 39 16 / 18 Antioxidant (6PPD) (7) 2 1.5 CBS Accelerator (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 of grade N134 according to ASTM D-1765-2017 (5) Carbon black of grade N234 according to ASTM D-1765-2017 (6) SER 6266 from SER company (7) N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine Santoflex 6-PPD from Flexsys company (8) N-cyclohexyl-2-benzothiazole sulfenamide Santocure CBS from Flexsys company (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

[0089] The component values ​​are expressed in phr (parts by weight per hundred parts of elastomers).

[0090] The measured properties are expressed in the table below for each of the mixtures: First Mixture Second Mixture Fatigue resistance (ur) 100 177 tan^)max (60°C) 0.22 0.17 Petition 870250082245, dated 12 / 09 / 2025, pp. 31 / 39 17 / 18

[0091] 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., greater fatigue resistance of the rubber samples.

[0092] Initial endurance tests were carried out on a test machine that forced each tire to roll in 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.

[0093] Further strength tests were carried out on a testing machine that cyclically applied a transverse force and a dynamic overload to the tires. The tests were performed on the tires according to the invention under conditions identical to those applied to the reference tires.

[0094] 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 the tires according to the invention than for the reference tires.

[0095] A final test was carried out to reproduce a drastic tire skid. It consists of forcing the skid, simulating the limit beyond which the vehicle may roll over.

[0096] This test consists of a preliminary step of placing the tire in an oven in a dry environment at 65°C for 15 weeks.

[0097] The rolling on the test machine is then performed to make the tire travel more than 25,000 km at a speed of 40 km / h, with the tire being made to skid for about 20% of the rolling time. The tire is subjected to a load close to the nominal straight-line load and increased by about 40% during skidding. The skidding phases correspond to maximum lateral acceleration before a vehicle rolls over.

[0098] At the end of these tests, the tires are checked by shear interferometry (shearography) 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 Petition 870250082245, dated 12 / 09 / 2025, pp. 32 / 39 18 / 18 corresponds to a less damaged tire. A value equal to 100 is assigned to the most damaged reference tire. Reference tire, Tire of the invention, Grade 100, Greater than 100

[0099] At the end of the rolling process, the tires according to the invention exhibit less extensive damage than the reference tires.

[00100] In addition, rolling resistance measurements were performed.

[00101] The test results are shown in the following table. Rolling resistance measurements are expressed in Kg / t, and a value of 100 is assigned to the reference tire. Values ​​above 100 indicate better rolling resistance performance. Reference tire Tire of the invention Rolling resistance 100 101

[00102] Tests reveal that tires according to the invention allow preserving, and even slightly improving, rolling resistance performance compared to the reference tire. Petition 870250082245, dated 12 / 09 / 2025, pp. 33 / 39

Claims

1 / 3 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 cuts consisting of at least one groove (7) consisting of two walls leading to the rolling surface and a surface joining the two walls, forming the bottom of said at least one groove (7), at least one protrusion (9) made of the material being present at the bottom of said at least one groove (7), the height d9 of said protrusion (9) being greater than 10% of the depth d7 of said at least one groove (7) and less than the height d7 of said at least one groove (7), the width of said protrusion (9),measured in a direction orthogonal to the walls of said at least one groove (7), being greater than or equal to 40% of the width of said at least one groove (7), measured in a direction orthogonal to the walls of said at least one groove (7), and less than said width of said at least one groove, and said protrusion (9) being joined to the bottom of said at least one groove (7) by junction areas, characterized in that the tread is made up of at least one first elastomeric mixture forming at least part of the rolling surface (6) when the tire is new,wherein at least part of the bottom of said at least one groove (7) surrounding the junction areas between said at least one protrusion (9) and the bottom of said at least one groove (7) is made of a second elastomeric mixture with a thickness E of at least 1 mm and wherein the second elastomeric mixture has a fatigue strength greater than at least 30% of the fatigue strength of the first elastomeric mixture, 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 groove (7) is a longitudinally oriented groove.

3. Tire (1), according to claim 1, characterized by the said Petition 870250082245, of 12 / 09 / 2025, page 34 / 39 2 / 3 less one groove being a transverse orientation groove.

4. Tire (1), according to claim 1, characterized in that said at least one groove is an obliquely oriented groove.

5. Tire (1), according to any one of claims 1 to 4, characterized in that the bottom and walls of said groove (7) are made of the second elastomeric mixture with a thickness of at least 1 mm.

6. Tire (1), according to any one of claims 1 to 5, characterized in that the thickness E 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 said at least one protrusion (9) present in said at least one groove (7) is continuous along the length of said groove (7).

8. Tire (1), according to any one of claims 1 to 6, characterized in that said at least one protrusion (9) present in said at least one groove (7) is discontinuous along the length of said groove (7).

9. Tire (1), according to any one of claims 1 to 8, characterized in that the second elastomeric mixture has a fatigue resistance greater than at least 50% of the fatigue resistance of the first elastomeric mixture, measured at 23°C up to an elongation of 108% in accordance with ISO 69432017.

10. Tire (1), according to any one of claims 1 to 9, characterized in that the first elastomeric mixture has a maximum value of tan(õ), indicated as tan(õ)max, less than 0.25, and the measurement of tan(õ) is carried out at 60°C in accordance with ASTM D 5992-96.

11. Tire (1), according to any one of claims 1 to 10, 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.

12. Tire (1), according to any one of claims 1 to 11, characterized in that the second elastomeric mixture is a rubber composition based on at least one elastomeric matrix comprising at least 25% of Petition 870250082245, dated 12 / 09 / 2025, p. 35 / 39 3 / 3 at least one butadiene-based synthetic elastomer and at least one reinforcing filler. Petition 870250082245, dated 12 / 09 / 2025, p. 36 / 39

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