Tire with corrugated crown layer and sidewall stiffening inserts - Patents.com

Abstract

The present invention relates to a tire (10) not suitable for runflat, comprising a crown block (12), two beads (32) and two sidewalls (30) connecting each bead (32) to the crown block (12). The crown block (12) comprises a crown reinforcement (16) comprising a corrugated crown layer (24, 26, 28) with corrugations. The sidewall (30) comprises a sidewall insert (90) comprising a so-called hard elastomer composition (92) having a modulus at 10% elongation of at least 6 MPa and a maximum thickness (Emax) of at most 5.0 mm.

Description

[Technical field]

[0001] The present invention relates to a tire. The term "tire" should be understood to mean a tire casing intended to cooperate with a support element, for example a rim, to form a cavity, said cavity being pressurizable to a pressure above atmospheric pressure. The tire according to the invention has a substantially toroidal structure exhibiting rotational symmetry about the main axis of the tire. [Background technology]

[0002] A tire comprising a crown block, two beads and two sidewalls connecting each bead to the crown block is known from EP 3529087. The crown block comprises a tread and a crown reinforcement arranged radially inside the tread. The crown reinforcement comprises a working reinforcement with two working layers and a hoop reinforcement with a hoop layer, the hoop reinforcement being arranged radially outside the working reinforcement. Each working layer and the hoop layer comprises a number of corrugations. Each corrugation of each crown layer comprises a crest and first and second bases adjacent to the crest, the bases being configured such that the crest is axially located between the first and second bases and the crest is radially outside each of the first and second bases. Due to the presence of corrugations, each layer of the crown reinforcement having at least one corrugation is called a corrugated crown layer.

[0003] Due to the corrugated crown layer, such a tire has a crown block with very high lateral, vertical and cornering stiffness, in any event much higher than that of a similar tire with a substantially cylindrical crown layer without corrugations.

[0004] Despite these high levels of stiffness, it has been surprisingly observed that vehicles equipped with such tires do not perform at the level expected with a corrugated crown layer (although this level of behavior is still better than that of tires without the corrugated crown layer). Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to improve the behavior of vehicles equipped with tires comprising at least one corrugated crown layer. [Means for solving the problem]

[0006] The invention therefore relates to a tire not suitable for runflat, comprising a crown block, two beads and two sidewalls connecting each bead to the crown block, the crown block comprising a tread and a crown reinforcement arranged radially inside the tread, the crown reinforcement comprising a central part having an axial width equal to 80% of the axial width of the crown reinforcement and axially centred on the median plane of the tire, the crown reinforcement comprising at least one crown layer, called a corrugated crown layer, comprising reinforcing elements embedded in a polymer matrix, the corrugated crown layer comprising at least one corrugation in the central part of the crown reinforcement, the or each corrugation of the corrugated crown layer comprising a top part of the corrugated crown layer and first and second bottom parts of the corrugated crown layer adjacent to the top part, the top portion is axially disposed between the first and second bottom portions; the top portion is disposed radially outward of each of the first and second bottom portions; The following are arranged in such a way that The tire comprises a sidewall insert axially disposed between an outer surface of at least one of the sidewalls and an inner surface of the sidewall, the sidewall insert comprising at least one elastomeric composition, referred to as a hard elastomeric composition, the or each hard elastomeric composition of the sidewall insert having a modulus of elasticity at 10% elongation of at least 6 MPa, and the maximum thickness of the hard elastomeric composition or of the assembly of hard elastomeric compositions being at most 5.0 mm.

[0007] To create the invention, the inventors had to understand why the achieved behavior was not at the expected level. After many tests, the inventors discovered that the sidewall of the tire forms a flexible portion lying between two rigid portions formed by the crown reinforcement and each bead.

[0008] In fact, each bead is rigid, in particular as a result of the materials from which it is made and its considerable thickness, due to its function as the contact point with the support on which the tire is mounted, such as the rim. These materials include in particular reinforcing elements, which are generally metallic or elastomeric compositions with a high level of rigidity, for example with a modulus of elasticity at 10% elongation of more than 20 MPa.

[0009] On the other hand, since the crown reinforcement has at least one corrugated crown layer, it is also relatively stiff, certainly stiffer than a crown reinforcement without a corrugated crown layer.

[0010] Thus, when the tire is subjected to a high load, the stiff parts formed by the crown reinforcement and the beads transmit a relatively high proportion of this load to the less stiff parts of the tire, in this case the sidewalls, which, however, are located radially between the beads and the crown blocks comprising the crown reinforcement, and therefore deflect with relatively large amplitudes, which explains why the behavior is not at the expected level.

[0011] Once the reasons for the behavior were understood, the inventors who created this invention also needed to find a technical solution that offered the best performance compromise.

[0012] As a result, the inventors have discovered that using a sidewall insert with a relatively high level of stiffness (in any case higher than the stiffness of the elastomeric compositions conventionally used in tire sidewalls) helps to reduce the amplitude of deflection of each sidewall when the tire is subjected to high loads, thereby improving vehicle behavior.

[0013] Furthermore, the use of the sidewall insert according to the invention has the advantage that it offers a better compromise between its manufacturing costs and its behavior, unlike other solutions, such as, for example, the use of reinforced carcass reinforcements: in fact, the manufacturing costs of a tire according to the invention are not significantly increased compared to a tire without a sidewall insert, since the sidewall insert at least partially replaces the material already used in the tire's sidewall.

[0014] The modulus at 10% elongation, commonly referred to as MA10, is the modulus of elasticity of the mixture measured during a uniaxial tensile test at an elongation value of 0.1 (i.e. 10% elongation expressed as a percentage). The specimen is subjected to a uniaxial tension at a constant rate and the elongation and force are measured. The measurements are carried out with an INSTRON® type tensile tester at a temperature of 23° C. and a relative humidity of 50% (ISO 23529 standard). The conditions for carrying out the measurements and using their results to determine the elongation and stress are as described in the NF ISO 37:2012-03 standard. The stress is determined for an elongation of 0.1 and the tensile modulus at 10% elongation is calculated as the ratio between this stress value and the elongation value. A person skilled in the art knows how to select and adapt the dimensions of the specimens depending on the amount of the mixture available and available, especially when taking specimens from tires.

[0015] The elastomeric composition of the sidewall insert is made from one or more elastomers and may contain fillers and other ingredients routinely used in the field of tire compositions.

[0016] The tire according to the invention is not suitable for run-flat. A tire suitable for run-flat is suitable for running when the pressure in the internal cavity of the tire is equal to atmospheric pressure (often referred to as zero pressure due to the use of inappropriate language, which is an overpressure relative to atmospheric pressure). A tire suitable for run-flat has a self-supporting sidewall, i.e. a sidewall that, at a pressure equal to atmospheric pressure, can withstand the same load as the tire can withstand when inflated to a normal pressure, for example a nominal pressure as shown in the European Tire and Rim Technical Organisation (ETRTO) Standards Manual 2021, over a distance equal to or greater than a certain threshold, at a speed of 80 km / h or more. Thus, a tire suitable for run-flat is such that, under the load ratings and atmospheric pressure as shown in the ETRTO Standards Manual 2021, the or each sidewall cannot flex itself in such a way as to bring two parts of the tire separated from each other into contact with each other. Conversely, a tire that is not suitable for runflat is one in which, under the rated load and atmospheric pressure set out in the ETRTO Standards Manual 2021, the or each sidewall is adapted to flex on itself in such a way as to bring two parts of the tire separated from each other into contact.

[0017] Tyres suitable for runflat preferably have a specific marking indicating the tyre's capability to run flat. Thus, for example, the following acronym-form markings are used, this list being non-exhaustive: "ZP" for "Zero Pressure", "SST" for "Self Supporting Technology", "SSR" for "Self Supporting Runflat Tyre", "RF" for "Run Flat", "RFT" for "Run Flat Tyre", "EXT" for "Extended", "ZP-SR" for "Zero Pressure Short Range" or even "ZPS" for "Zero Pressure System". Another specific indication of the tyre's capability to run flat is the presence of the letter "F" in the dimensional number of the tyre. Thus, a tire of size 225 / 40R18 or 225 / 40ZR18, if suitable for runflats, would be stamped 225 / 40RF18 or 225 / 40ZRF18.

[0018] The maximum thickness of the hard elastomer composition or the hard elastomer composition aggregate is the maximum value of the thickness of the hard elastomer composition or the hard elastomer composition aggregate, which thickness can be constant or variable. The thickness of the hard elastomer composition or the hard elastomer composition aggregate is defined as the thickness of the hard elastomer composition or the hard elastomer composition aggregate at a point on the inner surface of the tire in a meridian section. The thickness of the hard elastomer composition or the hard elastomer composition aggregate at this point on the inner surface is the linear distance between the radially innermost point of the hard elastomer composition or the hard elastomer composition aggregate and the radially outermost point of the hard elastomer composition or the hard elastomer composition aggregate along the normal to the inner surface at this point on the inner surface, these points of the sidewall insert being aligned along the normal to this point on the inner surface.

[0019] The inner surface defines the tire's internal cavity, which is intended to be pressurized with inflation gas once the tire is mounted on a mounting support, such as a rim. The inner surface of the sidewall is thus that portion of the sidewall which defines the tire's internal cavity.

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

[0021] In a preferred embodiment, the or each sidewall insert comprises a hard elastomeric composition. In a particular variant, the or each sidewall insert is made of a hard elastomeric composition. In another variant, the or each sidewall insert comprises a hard elastomeric composition and one or more elastomeric compositions, called flexible elastomeric compositions, whose modulus at 10% elongation is strictly less than 6 MPa. In these embodiments, the maximum thickness is the thickness of the hard elastomeric composition.

[0022] However, in other embodiments, it is also conceivable that the or each sidewall insert comprises a plurality of hard elastomeric compositions. In these embodiments, the maximum thickness is the maximum value with respect to the maximum thickness of the assembly of hard elastomeric compositions, i.e. the sum of the thicknesses of each hard elastomeric composition measured along the same normal to the inner surface of the tire. In certain variants of these embodiments comprising a plurality of hard elastomeric compositions, all of the elastomeric compositions of the sidewall insert are hard elastomeric compositions. In other variants of these embodiments comprising a plurality of hard elastomeric compositions, the sidewall insert comprises, in addition to the hard elastomeric compositions, one or more elastomeric compositions, called flexible elastomeric compositions, whose modulus at 10% elongation is strictly less than 6 MPa. In these other variants, the maximum thickness does not take into account the thickness of the or each flexible elastomeric composition, and the maximum thickness is defined as the maximum thickness of the assembly of hard elastomeric compositions.

[0023] The expression "a bottom adjacent to an apex" should be understood to mean that no other bottom is located axially between the apex and each adjacent bottom.

[0024] Unless the or each corrugated crown layer describes a broken line with straight line segments in each meridian section, each corrugation comprises two inflection points located axially between the crest and each of the first and second roots. The expression "inflection points" should be understood to mean points at which the curvature direction of the or each corrugated crown layer changes in the meridian section.

[0025] The axial width of the crown reinforcement is the axial width of the layer of the crown reinforcement that has the widest axial width. The axial width is the axial distance between the axial ends of the layer. The or each layer of the crown reinforcement may be axially continuous or may be discontinuous between the axial ends. Conventionally, the crown reinforcement of a passenger car tire comprises a hoop reinforcement and a working reinforcement arranged radially inward of the hoop reinforcement, the hoop reinforcement being arranged radially between the tread and the working reinforcement, the hoop reinforcement comprising at least one hoop layer, and the working reinforcement comprising at least one working layer.

[0026] By the central portion being axially centered about the median plane of the tire, it is meant that each axial end of the central portion is located at an axial distance from the median plane of the tire equal to 40% of the axial width of the crown reinforcement.

[0027] The expression "reinforcing element" should be understood to mean an element that helps to mechanically reinforce the polymer matrix in which it is intended to be embedded.

[0028] Preferably, each reinforcing element is thread-like, i.e. the length of each reinforcing element is at least 10 times greater than the largest dimension of its cross-section, regardless of the shape of the cross-section, which may be circular, elliptical, oblong, polygonal, in particular rectangular or square or oval. In the case of a rectangular cross-section, the thread-like elements are strip-like.

[0029] The matrix is ​​said to be a polymer matrix because it is made from a polymer composition, which may include, for example, one or more polymers chosen from thermoplastic polymers, thermoset polymers, elastomers, thermoplastic elastomers, as well as fillers and other components routinely used in the field of tire compositions, in particular compositions for embedding reinforcing elements.

[0030] The tyre according to the invention has a substantially toroidal shape about an axis of rotational symmetry substantially coinciding with the axis of rotation of the tyre, which axis of rotational symmetry defines the three directions conventionally used by those skilled in the art: axial, circumferential and radial.

[0031] The expression "axial" should be understood to mean the axis of rotational symmetry of the tire, i.e. a direction substantially parallel to the axis of rotation of the tire.

[0032] The expression "circumferential" should be understood to mean a direction substantially perpendicular both to the axial direction and to the radius of the tire (in other words, tangent to a circle about the axis of rotation of the tire).

[0033] The expression "radial" should be understood to mean a direction along the radius of the tire, i.e. any direction intersecting the axis of rotation of the tire and substantially perpendicular to said axis.

[0034] The expression "median plane of the tire" (denoted M) should be understood to mean the plane perpendicular to the axis of rotation of the tire, located axially midway between the two beads and passing through the axial center of the crown reinforcement.

[0035] The expression "equatorial circumferential plane of the tire" should be understood to mean the combination of a plane passing through the tire's equator (designated E) in each meridian section and perpendicular to the median plane and to the radial direction. The equator of the tire is the axis, in a meridian section (plane perpendicular to the circumferential direction and parallel to the radial and axial directions), parallel to the tire's axis of rotation and equidistant between the radially outermost point of the tread intended to come into contact with the ground and the radially innermost point of the tire intended to come into contact with a support, for example the rim, the distance between these two points being equal to H.

[0036] The expression "meridian plane" should be understood to mean a plane parallel to and including the axis of rotation of the tire and perpendicular to the circumferential direction.

[0037] The expressions "radially inward of" and "radially outward of" should be understood to mean "closer to the tire's axis of rotation than" and "further from the tire's axis of rotation than", respectively. The expressions "axially inward of" and "axially outward of" should be understood to mean "closer to the tire's median plane than" and "further from the tire's median plane than", respectively.

[0038] The term "bead" should be understood as the part of the tire intended to enable the tire to be fixed to a mounting support, for example to a wheel with a rim. Each bead is therefore intended in particular to be in contact with the flange of the rim enabling the tire to be fixed. As a result, the radially outer edge of the bead outer surface of a tire is defined as the radially outermost point of the outer surface of the tire that comes into contact with a reference rim for measuring the tire when the tire is inflated to its rated pressure on the reference rim in accordance with the ETRTO Standards Manual 2021.

[0039] A range of values ​​expressed by the expression "between a and b" denotes a range of values ​​extending from greater than a to less than b (i.e. excluding the endpoints a and b), whereas a range of values ​​expressed by the expression "from a to b" means a range of values ​​extending from a to b (i.e. including the precise endpoints a and b).

[0040] In a particular preferred embodiment of the invention, the tire is intended for passenger vehicles as defined in the ETRTO Standards Manual 2021. Such a tire has a cross section in a meridian section characterized by a section height H and a nominal section width S as defined in the ETRTO Standards Manual 2021, optionally such that the ratio H / S, expressed as a percentage, is at most equal to 90, preferably at most equal to 50, more preferably at most equal to 40, at least equal to 20, preferably at least equal to 25, and the nominal section width S is at least equal to 155 mm, preferably at least equal to 205 mm, more preferably at least equal to 225 mm, at most equal to 385 mm, preferably at most equal to 335 mm. Furthermore, the rim flange diameter D, which defines the diameter of the rim for mounting the tire, is at least equal to 12 inches, preferably at least equal to 16 inches and at most equal to 24 inches.

[0041] For every crown layer, a continuous surface, called the radially outer surface (SRE) of the layer, passing through the radially outermost point of each reinforcing element, and a continuous surface, called the radially inner surface (SRI) of the layer, passing through the radially innermost point of each reinforcing element, are defined. The radial distance between the layer of reinforcing elements and any other point is measured from one of these surfaces, without including the radial thickness of the layer. If the other measurement point is located radially outside the layer of reinforcing elements, the radial distance is measured from the radially outer surface SRE at this point. If the other measurement point is located radially inside the layer of reinforcing elements, the radial distance is measured from the radially inner surface SRI at this point.

[0042] In a preferred embodiment, the or each corrugation has a maximum radial amplitude of at least 1.0 mm, preferably at least 1.5 mm. In another preferred embodiment, the or each corrugation has a maximum radial amplitude of at most 3.0 mm, preferably at most 2.5 mm.

[0043] The expression "maximum radial amplitude" of a waveform should be understood to mean the linear radial distance between a point on the radially outer surface SRE of the waveform's apex and a point on the radially innermost bottom surface SRE of one of the waveform's first and second bottoms.

[0044] In a preferred embodiment, over at least 10%, preferably at least 20%, of the axial width of the corrugated crown layer separating the respective first and second roots of the or each corrugation, the radial distance between the radially outer SRE of one of the first and second roots of the or each corrugation and a point of the radially outer SRE of the radially innermost root is 1.0 mm or more, preferably 1.5 mm or more. In another preferred embodiment, over at least 10%, preferably at least 20%, of the axial width of the corrugated crown layer separating the respective first and second roots of the or each corrugation, the radial distance between the radially outer SRE of one of the first and second roots of the or each corrugation and a point of the radially outer SRE of the radially innermost root is 3.0 mm or less, preferably 2.5 mm or less.

[0045] In a preferred embodiment, the corrugated crown layer is the radially outermost layer of the crown reinforcement. In a particular embodiment for passenger tires, the radially outermost layer of the crown reinforcement is the hoop layer.

[0046] In an advantageous embodiment, the or each corrugated crown layer comprises a plurality of corrugations.

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

[0048] In one optional embodiment, each sidewall comprises a sidewall insert axially disposed between an outer surface of the sidewall and an inner surface of the sidewall, each sidewall insert comprising at least one elastomeric composition, referred to as a hard elastomeric composition, wherein the or each hard elastomeric composition of each sidewall insert has a modulus of elasticity at 10% elongation of 6 MPa or greater, and the maximum thickness of the hard elastomeric composition or assembly of hard elastomeric compositions is 5.0 mm or less.

[0049] As a result, in a first variant, two sidewall inserts can be arranged on the two sidewalls of the tire, these two sidewall inserts having the same maximum thickness and the same hard elastomer composition(s).

[0050] In a second variant, two sidewall inserts can be arranged on the two sidewalls of the tire, these two sidewall inserts having one or more hard elastomer compositions with different maximum thicknesses and / or different moduli at 10% elongation. In particular, when the tire has a mounting direction pointing to the outside and to the inside when it is mounted on the vehicle, preference is given to the scenario in which the insert of the sidewall intended for the outside has one or more hard elastomer compositions with a maximum thickness and / or moduli at 10% elongation greater than the insert of the sidewall intended for the inside.

[0051] In one optional embodiment, the tread comprises at least one rib and first and second notches adjacent to the rib, the tops of the corrugations of the corrugated crown layer being aligned with the rib and the first and second bottoms of the corrugations of the corrugated crown layer being aligned with the first and second notches adjacent to the rib, respectively.

[0052] The portion of the corrugated crown layer that is aligned with a rib or a notch is an axial portion of the corrugated crown layer bounded by axial ends defined by two circumferential surfaces that are perpendicular to the tire's rotational axis and pass through the axial ends of the rib or the notch, respectively. Thus, the tops of the corrugations of the corrugated crown layer are aligned with the rib when they are axially located between the two circumferential surfaces that pass through the axial ends of the rib. Similarly, the bottoms of the corrugations of the corrugated crown layer are aligned with the notch when they are axially located between the two circumferential surfaces that pass through the axial ends of the notch.

[0053] The expression "a notch adjacent to a rib" should be understood to mean that no other notches are located axially between the notch and the rib.

[0054] The incision means either a groove or a sipe, which forms an open space on the tread surface.

[0055] A sipe or groove has two main characteristic dimensions in the tread surface, a width and a curvilinear length, such that the curvilinear length is at least equal to twice the width. A sipe or groove thus determines its curvilinear length and is bounded by at least two major side surfaces joined at a base, the two major side surfaces being separated from each other by a non-zero distance called the width of the cut.

[0056] The width of a cut is the maximum distance between the two major sides of a new tire, measured in a radial dimension coincident with the tread surface if the cut is not chamfered, or in a radially outermost dimension of the cut radially inward of the chamfer if the cut is chamfered, the width being measured substantially perpendicular to the major sides.

[0057] The axial width of the incision is measured in the axial direction of the tire, for example in a meridian section of the tire.

[0058] The sipes are such that the distance between the major sides defining the sipes is suitable for the major sides to at least partially contact the ground contact surface, particularly when the tire is new and under normal running conditions, including in particular when the tire is under rated load and at rated pressure.

[0059] The grooves are such that the distance between the major sides is such that the major sides cannot contact each other under normal operating conditions, including, inter alia, when the tire is under rated load and at rated pressure.

[0060] The cuts can be transverse or circumferential.

[0061] The transverse cuts are such that they extend in a mean direction that forms an angle with the circumferential direction of the tire strictly greater than 30°, preferably greater than 45°. The mean direction is the shortest curve that connects the two ends of the cut and is parallel to the tread surface. The transverse cuts can be continuous, i.e. not interrupted by a tread pattern or by another cut, so that the two main sides determining their length are uninterrupted along the length of the transverse cut. The transverse cuts can also be discontinuous, i.e. interrupted by one or more tread patterns and / or one or more cuts, so that the two main sides determining their length are interrupted by one or more tread patterns and / or one or more cuts.

[0062] The circumferential cuts are such that they extend in a mean direction that forms an angle of not more than 30°, preferably not more than 10°, with the circumferential direction of the tire. The mean direction is the shortest curve that connects the two ends of the cut and is parallel to the tread surface. In the case of a continuous circumferential cut, the ends coincide with each other and are connected by a curve that goes around the tire. The circumferential cuts can be continuous, i.e. not interrupted by a tread pattern or another cut, so that the two main sides determining its length are uninterrupted over the entire circumference of the tire. The circumferential cuts can also be discontinuous, i.e. interrupted by one or more tread patterns and / or one or more cuts, so that the two main sides determining its length are interrupted by one or more tread patterns and / or one or more cuts over the entire circumference of the tire.

[0063] For a circumferential cut located outside the median plane of the tire, the sides are referred to as the axially inner and axially outer surfaces, with the axially inner surface being located axially inward of the axially outer surface with respect to the median plane at a given azimuth angle.

[0064] Each circumferential cut has an axially inner end and an axially outer end, and whether or not the circumferential cut has a chamfer, each axially inner and outer end is located at a respective axial inner or outer edge, respectively.

[0065] In the case of a lateral cut, the sides are referred to as the leading and trailing sides, the leading side being the side whose edge enters the ground contact patch before the edge of the trailing side for a given circumferential line.

[0066] In an embodiment, the or each circumferential cut is chamfered. The chamfer of the circumferential cut can be an angular chamfer or a rounded chamfer. An angular chamfer is formed by a plane inclined relative to the inner and outer axial surfaces, the plane extending to an inner or outer axial edge axially delimiting the circumferential cut. A rounded chamfer is formed by a curved surface tangentially merging into the inner or outer axial surface it extends from. A chamfer of a circumferential cut is characterized by a height and a width, which are equal to the radial and axial distances, respectively, between a point common to the inner or outer axial surface extended by the chamfer and the inner or outer axial edge axially delimiting the circumferential cut.

[0067] In some embodiments, the or each transverse cut is chamfered. In other words, each transverse cut is radially delimited by a front and a rear face that are joined to each other by a base face that circumferentially delimits the transverse cut and radially delimits the transverse cut inwardly. The chamfer of the transverse cut can be an angular chamfer or a rounded chamfer. An angular chamfer is formed by a plane that is inclined relative to the front or rear face and extends to a leading or trailing edge that circumferentially delimits the transverse cut. A rounded chamfer is formed by a curved surface that tangentially merges with the front or rear face to which it extends. The chamfer of the transverse cut is characterized by a height and a width that are equal to the radial distance between the common point of the front or rear face that is extended by the chamfer and the leading or trailing edge that circumferentially delimits the transverse cut, and the distance perpendicular to the front or rear face, respectively.

[0068] For a new tire, the cut depth is the maximum radial distance between the bottom of the cut and its projection on the ground when the tire is running. The maximum cut depth is called the tread pattern height.

[0069] In embodiments in which each of the first and second adjacent circumferential cuts is relatively wide, particularly for passenger tires, each of the first and second adjacent circumferential cuts has an axial width of 1.0 mm or more, preferably 4.0 mm or more, and more preferably in the range of 4.0 mm to 20.0 mm.

[0070] In embodiments where each of the first and second adjacent circumferential cuts is relatively deep, particularly for passenger tires, each of the first and second adjacent circumferential cuts has a depth of 50% or more of the tread pattern height Hs. Thus, preferably, each of the first and second adjacent circumferential cuts has a depth in the range of 4.0 mm to the tread pattern height.

[0071] In a highly advantageous embodiment, the tread comprises a plurality of ribs and a plurality of notches, each rib of the plurality of ribs having adjacent first and second notches of the plurality of notches, and the corrugated crown layer comprises a plurality of corrugations in a central portion of the crown reinforcement, the top of each corrugation of the corrugated crown layer being aligned with one of the ribs, and each first and second bottom of each corrugation of the corrugated crown layer being aligned with each first and second notch adjacent the rib, respectively.

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

[0073] In an advantageous variant in which the corrugated crown layer is the radially outermost layer of the crown reinforcement, - a radial minimum distance between the or each crest of the or each corrugation of the radially outermost layer of crown reinforcement and the tread surface; a depth of the or each circumferential cut at which each first and second root of the or each corrugation is located; The difference is less than 2 mm.

[0074] The minimum radial distance between the crest of the or each corrugation and the tread surface is measured in this example between the radially outer surface SRE of the corrugated crown layer and the tread surface.

[0075] In an advantageous embodiment, the or each hard elastomeric composition has a modulus at 10% elongation of not more than 20 MPa, preferably not more than 15 MPa, more preferably not more than 13 MPa. This improves the vehicle's behavior, but excessive stiffness may still reduce the comfort of the vehicle. Moreover, excessive stiffness may reduce flattening and reduce the surface area of ​​the ground contact patch. It is therefore preferable to use a sidewall insert that is not too stiff.

[0076] In an advantageous embodiment, the maximum thickness of the hard elastomer composition or of the mass of hard elastomer compositions ranges from 1.0 mm to 5.0 mm, preferably from 1.0 mm to 3.5 mm, more preferably from 1.0 mm to 2.5 mm, and even more preferably from 1.2 mm to 1.7 mm. This stiffness is considerably greater than that of compositions conventionally used in tire sidewalls, but the greater the maximum thickness, the greater the improvement in the vehicle's behavior. However, exceeding an excessive maximum thickness reduces the comfort of the vehicle, as well as flattening, which leads to a reduction in the surface area of ​​the contact patch.

[0077] In another advantageous embodiment, the or each sidewall has a minimum thickness at a point I, the thickness of the sidewall at a point on its inner surface is defined as the linear distance between this point on the inner surface and a point on the outer surface of the tire aligned with this point on the inner surface along the normal to the inner surface at this point on the inner surface, the point on the inner surface at which the thickness of the hard elastomeric composition or of the aggregate of hard elastomeric compositions is maximum is defined as: - a radially outer straight line formed by a normal to the inner surface passing through a point on the inner surface located 10 mm radially outside point I; - a radially inner straight line formed by a normal to the inner surface passing through a point on the inner surface located 10 mm radially inward of point I; The electrodes are arranged radially between the electrodes.

[0078] In other words, the thickness of the hard elastomeric composition or of the mass of hard elastomeric compositions is greatest near the area where the sidewall has its minimum thickness. In fact, for the same stiffness, the sidewall will deflect the most where it has its minimum thickness. Therefore, in order to effectively improve the behavior of the vehicle, it is advantageous to make the sidewall stiffer in this area that may experience high degrees of deflection.

[0079] Optionally, the thickness of the hard elastomeric composition or mass of hard elastomeric compositions is greatest radially outward of the equator of the tire.

[0080] In an advantageous embodiment, the radially outer end of the sidewall insert is located radially outward of the equator of the tire.

[0081] Advantageously, optionally, the radially outer end of the sidewall insert is disposed radially and axially inward of a line perpendicular to the inner surface and passing through the axially outer end of the axially widest crown layer of the crown reinforcement.

[0082] In fact, the sidewall insert would unnecessarily increase the weight and rolling resistance of the tire by extending beyond the axially outer end of the axially widest crown layer.

[0083] In an embodiment, the radially outer end is the radially outer end of the hard elastomeric composition or the radially outer end of the mass of hard elastomeric compositions, hi another embodiment, the radially outer end is the radially outermost end of the hard elastomeric composition or the radially outer end of the flexible elastomeric composition of the insert.

[0084] In another advantageous embodiment, the radially inner end of the sidewall insert is located radially inward of the equator of the tire.

[0085] Advantageously, and optionally, the radially inner end of the sidewall insert is disposed radially and axially outboard of a line perpendicular to the inner surface and passing through the radially outer end of the outer surface of the bead of the tire.

[0086] In fact, the sidewall insert does not need to extend too far radially inward, especially into the bead, because, as pointed out in the introduction, this area of ​​the tire is already sufficiently stiff, which would make the tire unnecessarily heavy.

[0087] In an embodiment, the radially inner end is the radially inner end of the hard elastomeric composition or the radially inner end of the hard elastomeric composition of the mass, hi another embodiment, the radially inner end is the radially innermost end of the hard elastomeric composition or the flexible elastomeric composition of the insert.

[0088] Optionally but advantageously, the or each sidewall insert has a generally crescent-shaped cross-section, such that the cross-sectional width of the sidewall insert is smallest at its radially inner and outer ends and greatest therebetween.

[0089] Optionally, the tire comprises a carcass reinforcement including at least one carcass layer anchored to the or each bead and extending radially within the or each sidewall and axially within the crown block radially inward of the crown reinforcement.

[0090] Optionally, the or each carcass layer is axially bounded by two axial ends and optionally and preferably comprises carcass reinforcing elements extending axially from one axial end to the other axial end of the carcass layer in a main direction which forms an angle, expressed in absolute value, with the circumferential direction of the tire of at least 60°, preferably in the range 80° to 90°.

[0091] In a particular embodiment, the tire includes an airtight inner layer supporting an inner surface thereof, the sidewall insert being axially disposed between the airtight inner layer and the axially innermost carcass layer.

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

[0093] In particular variants, the carcass reinforcement comprises a single carcass layer anchored to the or each bead and extending radially in each sidewall and axially in the crown block radially inside the crown reinforcement. In these variants, the invention makes it possible in particular to avoid the addition of a second carcass layer, or indeed the use of reinforced carcass reinforcing elements, to improve the vehicle's behavior. The expression "single carcass layer anchored to the or each bead" should be understood to mean that the carcass reinforcement is not provided with any layer reinforced with reinforcing elements anchored to the or each bead, apart from this carcass layer. Reinforcing elements of such a reinforcing layer excluded from the carcass reinforcement of the tire include metal reinforcing elements and textile reinforcing elements. Very preferably, the carcass reinforcement is made up of a single carcass layer. Even more preferably, the tire comprises a single carcass layer extending at least radially in each sidewall and a radially inner end located radially inside the equator of the tire; a radially outer end located radially outside the equator of the tire; The sidewall reinforcing layer is not provided.

[0094] Thus, the eliminated sidewall reinforcing layer is discontinuous under the crown of the tire. The eliminated sidewall reinforcing layer is not anchored to the bead of the tire. As a result, the radially inner end of the eliminated sidewall reinforcing layer is located radially outward of the bead.

[0095] In another variant, the carcass reinforcement comprises a first and a second single carcass layer anchored to the or each bead and extending radially in each sidewall and axially in the crown block radially inside the crown reinforcement, the sidewall insert being arranged axially inside the first carcass layer. In these other variants, the invention makes it possible in particular to avoid the use of sidewall reinforcing layers for improving the vehicle behavior or the use of reinforced carcass reinforcing elements. As mentioned above, it is possible to envisage the sidewall insert being arranged axially inside the axially innermost carcass layer. It is also possible to envisage the sidewall insert being arranged axially between the first and second carcass layers.

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

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

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

[0099] Optionally, the or each working layer is axially delimited by two axial ends, the or each working layer comprising working reinforcing elements 240 which extend axially from one axial end to the other axial end, substantially parallel to one another in a main direction which forms with the circumferential direction of the tire 10 an angle strictly greater than 10° in absolute value, preferably ranging from 15° to 50°, more preferentially ranging from 25° to 45°.

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

[0101] Preferably, the or each hoop reinforcing element and working reinforcing element is a thread-like reinforcing element.

[0102] Preferably, when the tire is inflated to its rated pressure, the inner surface does not have an inflection point located along the crown reinforcement, the portion of the inner surface located along the crown reinforcement being the portion of the inner surface axially located between the axial boundary edges of the axially widest crown layer projected radially onto the inner surface.

[0103] Preferably, in each meridian plane, the or each central rib has a substantially flat tread surface intended to come into contact with the ground. The expression "substantially flat" should be understood to mean that the radial distance between the radially outermost point(s) of the tread surface of said central rib and the radially innermost point(s) of the tread surface is strictly less than 0.2 mm, preferably less than or equal to 0.1 mm and more preferably substantially zero. A central rib is a rib located axially between two adjacent circumferential cuts.

[0104] The invention will be understood more clearly on reading the following description, given purely by way of non-limiting example and in conjunction with the drawings in which: [Brief description of the drawings]

[0105] [Figure 1]1 is a meridian section, parallel to the axis of rotation of a tire, of a tire according to a first embodiment of the invention; FIG. [Diagram 2] FIG. 2 is a detailed view of one sidewall of the tire of FIG. 1. [Diagram 3] FIG. 2 is a detail view of a crown block of the tire of FIG. 1. [Figure 4] FIG. 2 is a view similar to FIG. 1 for a tire according to a second embodiment of the invention. [Diagram 5] FIG. 2 is a view similar to FIG. 1 for a tire according to a third embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0106] Reference systems X, Y, Z, which correspond respectively to the normal axial (Y), radial (Z) and circumferential (X) directions of the tire, are shown in the diagram for the tire.

[0107] Figure 1 shows a tire according to the invention, designated by the general reference number 10. The tire 10 has a substantially toroidal shape about an axis of rotation substantially parallel to an axial direction Y. The tire 10 is intended for passenger cars and has the dimensions 245 / 35R20. The tire 10 is not suitable for run-flats. In the various figures, the tire 10 is shown as new, i.e. before it has been driven.

[0108] The tire 10 comprises a crown block 12 with a tread 14 intended to come into contact with the ground when running, and a crown reinforcement 16 extending in the crown block 12 in a circumferential direction X. The tire 10 also comprises an airtight inner layer 18 intended to be airtight against inflation gas and to define an internal cavity with the mounting support of the tire 10 once the tire 10 is mounted on a mounting support, for example a rim, this internal cavity being intended to be pressurized with inflation gas. The airtight inner layer 18 carries an inner surface 19 of the tire 10. The tire 10 also has an outer surface 31.

[0109] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22, each of which comprises at least one crown layer. The working reinforcement 16 comprises at least one working layer, in this case two working layers, a radially outer working layer 26 and a radially inner working layer 24 disposed radially inwardly thereof.

[0110] The hoop reinforcement 22 comprises at least one hoop layer, in this case one hoop layer 28 .

[0111] The crown reinforcement 16 is arranged radially inside the tread 14. In this case, the hoop reinforcement 22, in this case the hoop layer 28, is arranged radially outside the working reinforcement 20 and is thus interposed radially between the working reinforcement 20 and the tread 14.

[0112] The tire 10 includes two sidewalls 30 extending radially inwardly from the crown block 12. The tire 10 further includes two beads 32 radially inwardly of the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown block 12. Each sidewall 30 bears on a portion of its outer surface 31.

[0113] The tire 10 comprises a carcass reinforcement 34. The crown reinforcement 16 is disposed radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass layer 36, in this case a single carcass layer 36. The carcass reinforcement 34 extends radially at each sidewall 30, axially at the crown blocks 12, and radially inward of the crown reinforcement 16.

[0114] To anchor the carcass layer 36, the tire 10 comprises an axially inner circumferential reinforcing element 38 arranged axially inside the carcass layer 36 and an axially outer circumferential reinforcing element 40 arranged axially outside the carcass layer 36. In this case, each reinforcing element 38, 40 comprises a continuous thread-like reinforcing element wound multiple times in the circumferential direction, as described, for example, in WO 2021 / 123522.

[0115] The crown reinforcement 16 comprises two axial ends 161, 162, which in this case coincide with the ends of the axially widest layer of the crown reinforcement 16. The crown reinforcement 16 comprises a central part P0 having an axial width L0 equal to 80% of the axial width L of the crown reinforcement 16, in this case the axial width of the hoop layer 28, and axially centred on the median plane M. The crown reinforcement 16 also comprises side parts P1, P2, arranged axially on either side of the central part P0, each having an axial width L1=L2 equal to 10% of the axial width L of the crown reinforcement 16.

[0116] When the tire is inflated to its rated pressure, the inner surface 19 has no inflection point located along the crown reinforcement 16, i.e., the inner surface 19 has no inflection point between the axial ends 161,162.

[0117] Each of the working layers 24, 26, hoop layer 28 and carcass layer 36 comprises a polymer matrix, in this case an elastomeric matrix, in which is embedded one or more reinforcing elements of the corresponding layer, in particular the thread-like reinforcing elements described in particular with reference to Figures 1 and 3.

[0118] The hoop reinforcement 22, in this case the hoop layer 28, is axially delimited by two axial ends 161, 162. The hoop reinforcement 22 comprises one or more hoop thread reinforcing elements 280 wound helically in the circumferential direction so as to extend axially in a main direction D0 from one axial end to the other axial end of the hoop layer 28. The main direction D0 makes an angle AF with the circumferential direction X of the tire 10 having an absolute value of less than or equal to 10°, preferably less than or equal to 7°, more preferably less than or equal to 5°. In this case AF=-5°.

[0119] The radially inner working layer 24 is delimited axially by two axial ends. The radially inner working layer 24 comprises filamentary working reinforcing elements 240 which extend axially from one axial end to the other axial end in a main direction D1 substantially parallel to each other. Similarly, the radially outer working layer 26 is delimited axially by two axial ends. The radially outer working layer 26 comprises filamentary working reinforcing elements 260 which extend axially from one axial end to the other axial end in a main direction D2 substantially parallel to each other. Each of the main directions D1, D2 respectively form an angle AT1, AT2 with respect to the circumferential direction X of the tire 10, which has an opposite sense. Each of the main directions D1, D2 respectively form an angle AT1, AT2 with respect to the circumferential direction X of the tire 10, the absolute value of which is strictly greater than 10°, preferably lying in the range of 15° to 50°, more preferentially lying in the range of 25° to 45°. In this case, AT1 = -33° and AT2 = +33°.

[0120] The carcass layer 36 is axially delimited by two axial ends and comprises filamentary carcass reinforcing elements 360 extending axially from one axial end to the other in a main direction D3 that makes an angle AC with an absolute value greater than or equal to 60°, preferably ranging from 80° to 90°, with respect to the circumferential direction X of the tire 10, in which case AC=+90°.

[0121] Each filamentous hoop reinforcing element 280, the working reinforcing elements 240, 260 and the carcass reinforcing element 360 are, for example, identical to those described in WO 2021 / 123522.

[0122] 1 and 3, the tread 14 includes a tread surface 38 by which the tread 14 contacts the ground.

[0123] The tread 14 comprises a plurality of circumferential cuts, in this case a plurality of circumferential grooves, comprising first, second, third and fourth circumferential cuts, respectively designated by reference characters 52, 54, 56 and 58. Each circumferential cut 52 to 58 is bounded axially by an axially outer end, respectively designated by reference characters 521, 541, 561 and 581, and an axially inner end, respectively designated by reference characters 522, 542, 562 and 582. Each circumferential cut 52 to 58 has a depth, respectively designated by reference characters Ha1, Ha2, Ha3 and Ha4, ranging from 4.0 mm to the tread pattern height Hs. Each depth Ha1, Ha2, Ha3 and Ha4 is equal to or greater than 50% of the tread pattern height Hs. In this case, Hs=Ha2=Ha3=Ha4=7.5 mm, and Ha1=5.0 mm. Each of the circumferential cuts 52 to 58 has an axial width, designated by reference numbers La1, La2, La3, La4, respectively, which is greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, and more preferably in the range of 4.0 mm to 20.0 mm. In this case, La1=7.4 mm, La3=14.4 mm, La2=La4=18.0 mm.

[0124] The tread 14 also comprises a number of central ribs, in this case a first, second and third central rib, respectively designated by reference characters 62, 64 and 66. Each central rib 62, 64, 66 is axially disposed between two of the adjacent circumferential cuts 52 to 58 and is axially delimited by two adjacent circumferential cuts 52 to 58. Each central rib 62, 64, 66 is axially delimited by an axially inner end and an axially outer end, each of which is an axially inner end or an axially outer end of a circumferential cut 52 to 58. The axially inner and outer ends of each central rib 62, 64, 66 are adjacent to each other. In this particular case, the first central rib 62 is axially delimited by the axially inner end 522 of the circumferential cut 52 and the axially outer end 561 of the circumferential cut 56. The second central rib 64 is bounded axially by the axially inner end 562 of the circumferential cut 56 and the axially inner end 582 of the circumferential cut 58. The central rib 66 is bounded axially by the axially outer end 581 of the circumferential cut 58 and the axially inner end 542 of the circumferential cut 54. Thus, the circumferential cuts 52, 56 are adjacent to the rib 62, the circumferential cuts 56, 58 are adjacent to the rib 64, and the circumferential cuts 58, 54 are adjacent to the rib 66. Each central rib 62, 64, 66 has a substantially flat tread surface intended to contact the ground.

[0125] The tread 14 also includes first and second lateral ribs 68,70.

[0126] Although not shown in FIGS. 1 and 3, each of the central ribs 62,64,66 and each of the side ribs 68,70 includes a transverse notch formed therein.

[0127] Figure 3 shows the following: a radially outer surface SRE passing, in dotted lines, through the radially outermost points of the radially outermost reinforcing elements 240, 260 and 280 of each crown layer 24, 26, 28; - a radially inner surface SRI passing, in dotted lines, through the radially innermost points of the radially innermost reinforcing elements 240, 260 and 280 of each crown layer 24, 26, 28; - dashed lines, the interface of the polymer matrix in which the reinforcing elements of each crown layer 24, 26, 28 are embedded.

[0128] 1 and 3, each crown layer, in this case each working layer 24, 26 and hoop layer 28, comprises a plurality of corrugations 80 in the central portion P0 of the crown reinforcement 16, and is therefore referred to as a corrugated crown layer. Each corrugation 80 of each corrugated crown layer 24, 26, 28 comprises an apex 824, 826, 828 of each corrugated crown layer 24, 26, 28, respectively, a first bottom 844, 846, 848 of each corrugated crown layer 24, 26, 28, respectively, and a second bottom 844, 846, 848 of each corrugated crown layer 24, 26, 28, respectively. The apex and bottom are configured such that each apex 824, 826, 828 is axially disposed between the first and second bottom 844, between the first and second bottom 846, and between the first and second bottom 848, respectively. The apex and bottom portions are configured such that each apex portion 824, 826, 828 is disposed radially outward of the first and second bottom portions 844, the first and second bottom portions 846, and the first and second bottom portions 848, respectively. In FIG. 3, when radial distance needs to be measured, the apex portions 824, 826, 828 and the bottom portions 844, 846, 848 are utilized at the radially outer surface SRE of each layer of interest.

[0129] Each crest 824, 826, 828 of each corrugation 80 of each corrugated crown layer 24, 26, 28 is aligned with one of the central ribs 62, 64, 66. Each first and second bottom 844, 846, 848 of each corrugation 80 of each corrugated crown layer 24, 26, 28 is aligned with each first and second cutout 52 and 56, 56 and 58, 58 and 54 adjacent each rib 62, 64, 66, respectively.

[0130] Each maximum radial amplitude A1, A2, A3 of each corrugation 80 of each corrugated crown layer 24, 26, 28 is greater than or equal to 1.0 mm, preferably greater than or equal to 1.5 mm, and less than or equal to 3.0 mm, preferably less than or equal to 2.5 mm. In this particular case, each maximum radial amplitude A1, A2, A3 is substantially equal to 2.0 mm.

[0131] A radial distance between the radially outer surface SRE of one of the first and second bases 844, 846, 848 of each corrugation 80 and the radially innermost point of the radially outer surface SRE of the base 844, 846, 848 of each corrugation 80 over at least 10%, preferably at least 20%, of the axial width Lf1, Lf2, Lf3 of each corrugation crown layer 24, 26, 28 that separates each of the first and second bases 844, 846, 848 of each corrugation 80 is 1.0 mm or more, preferably 1.5 mm or more, and 3.0 mm or less, preferably 2.5 mm or less. In this particular case, this radial distance is 1.5 mm or more and 2.5 mm or less over about 30% of each axial width Lf1, Lf2, Lf3.

[0132] Furthermore, the difference between the minimum radial distance Dmin between each top 828 of each wave 80 of the hoop layer 28 and the tread surface 38 and the depths Ha2, Ha3, Ha4 of each circumferential cut 54, 56, 58 with which each first and second bottom 848 of each wave 80 of the hoop layer 28 are aligned is 2 mm or less.

[0133] The tire comprises two sidewall inserts 90. Each sidewall insert 90 is arranged axially between the outer surface 31 of one of the sidewalls 30 and the inner surface 19 of said sidewall 30. More precisely, each sidewall insert 90 is arranged axially between the airtight inner layer 18 and the axially innermost carcass layer (in this case the single carcass layer 36). Each sidewall insert 90 has a generally crescent-shaped cross section.

[0134] Each sidewall insert 90 comprises at least one elastomer composition, referred to as the hard elastomer composition. In this case, each sidewall insert 90 comprises a hard elastomer composition 92, which in this particular case is constituted by a hard, rigid elastomer composition 92. The hard elastomer composition 92 of each sidewall insert 90 has a modulus of elasticity at 10% elongation MA10 of 6 MPa or more and 20 MPa or less, preferably 15 MPa or less, more preferably 13 MPa or less. In this case MA10=8 MPa. To compound this hard elastomer composition, for example, the teachings of WO 2014 / 184158 or WO 2018 / 111773 can be used.

[0135] Each sidewall insert 90 has a radially outer end 94 and a radially inner end 96. Each radially outer end 94 is disposed radially outward of the equator E, perpendicular to the inner surface 19, and radially and axially inward of a straight line N1 passing through each axially outer end 161, 162 of the axially widest crown layer of the crown reinforcement 16, in this case the hoop layer 28. Each radially inner end 96 is disposed radially inward of the equator E, perpendicular to the inner surface 19, and radially and axially outward of a straight line N2 passing through the radially outer end 33 of the outer surface 31 of each bead 32.

[0136] 2, the thickness of the hard elastomer composition 92, and therefore the sidewall insert 90 in this case, is maximum radially outward of the equator E. In this particular case, the thickness of the hard elastomer composition 92, and therefore the sidewall insert 90 in this case, is maximum between a radially outward straight line formed by a normal N3 to the inner surface 19 passing through a point 93 of the inner surface 19 located 10 mm radially outward of point I, and a radially inward straight line formed by a normal N4 to the inner surface 19 passing through a point 95 of the inner surface 19 located 10 mm radially inward of this same point I. Point I is the point of each sidewall 30 that has a minimum thickness at point I, and the thickness of the sidewall 30 at a point of the inner surface 19 is defined as the straight-line distance along the normal N to the inner surface 19 at this point of the inner surface 19 between this point of the inner surface 19 and a point on the outer surface of the tire that is aligned with this point of the inner surface 19 along the normal N. In this case, point 97 is the point on the inner surface 19 where the thickness of the hard elastomeric composition 92, and therefore in this case the thickness of the sidewall insert 90, is at a maximum, and this point 97 on the inner surface 19 is located radially between the radially outer line N3 and the radially inner line N4. In this case, point 97 and point I are substantially coincident, i.e., the maximum thickness Emax is obtained substantially where the thickness of each sidewall 30 is at a minimum.

[0137] The maximum thickness Emax of the hard elastomeric composition 92, and thus in this case the sidewall insert 90, is less than or equal to 5.0 mm, preferably in the range of 1.0 to 5.0 mm, more preferably 1.0 to 3.5 mm, even more preferably 1.0 to 2.5 mm, and most preferably 1.2 to 1.7 mm, where Emax=1.5 mm and the minimum thickness Emin of each sidewall 30 is Emin=5.1 mm.

[0138] Tyres according to second and third embodiments of the invention will now be described with reference to Figures 4 and 5 respectively, in which elements similar to those shown in the previous figures are designated by the same reference numerals.

[0139] Unlike the tire according to the first embodiment, the tire 10 according to the second embodiment of FIG. 4 has a circumferential reinforcing element, in this particular case a bead wire 35, for anchoring the carcass layer 36, around which the carcass layer 36 is wound so as to form an axially inner portion 361 and an axially outer portion 362 arranged axially outside the axially inner portion 361.

[0140] Unlike the tires according to the first and second embodiments, the carcass reinforcement 34 of the tire 10 according to the third embodiment comprises first and second carcass plies 36, 37 anchored in each bead 32 and extending radially in each sidewall 30 and axially in the crown block 12, radially inside the crown reinforcement 16. The second carcass ply 37 is arranged axially and radially outside the first carcass ply 36. A sidewall insert 90 is arranged axially inside the first carcass ply 36.

[0141] Comparative Test

[0142] The tire 10 according to the first embodiment of the invention was compared with a reference tire T1 and a control tire T2. The reference tire T1, which is not according to the invention, has a corrugated crown layer but no sidewall insert. The control tire T2, which is not according to the invention, has a corrugated crown layer and a carcass reinforcement including first and second carcass layers but no sidewall insert.

[0143] The tires 10, T1 and T2 were tested to measure rolling resistance, weight, lateral stiffness, cornering stiffness, behavior during subjective tests called soft tests used to evaluate the behavior of a vehicle equipped with the tires under normal use conditions, and behavior during subjective tests called stress tests used to evaluate the behavior of a vehicle equipped with the tires under sports conditions that represent use in particular on circuit circuits.

[0144] The subjective tests were conducted on a circuit using a Ferrari 488GTB and a Porsche Panamera fitted with tires of different corresponding dimensions T10, T1 and T2.

[0145] The results of these tests are given in Table 1 below, where "Ref" indicates the corresponding performance reference value.

[0146] [Table 1]

[0147] Table 1 shows that the tire 10 helps to achieve a better vehicle behavior than the reference tire T1. Although the tire 10 according to the invention has a lower dynamic performance than the control tire T2, due in particular to its lower lateral and cornering stiffness, it nevertheless offers a significantly better compromise than the control tire T2 between behavior, weight and, above all, manufacturing costs and rolling resistance.

[0148] With regard to the manufacturing costs, the designation "+++" for the control tire T2 indicates that the manufacturing costs are much higher than those of the reference tire T1 and the tire 10 according to the invention.

[0149] For the soft test, the "+" designation for tire 10 indicates reduced understeer and improved high speed stability compared to the reference tire T1 and the control tire T2.

[0150] For the stress tests, the designation "++" for the control tire T2 indicates improved grip stability, improved cornering stiffness and improved oversteer behavior compared to the reference tire T1. The designation "+" for the tire 10 indicates improved grip stability, improved cornering stiffness and slightly improved oversteer behavior compared to the reference tire T1.

[0151] As a result, the present invention makes it possible to obtain a tire that performs beyond the level expected with a corrugated crown layer.

[0152] The present invention is not limited to the above-described embodiments. [Explanation of symbols]

[0153] 10 Tires 12 Crown Block 14 Tread 16 Crown Reinforcement 18 Airtight inner layer 19 Inner 20 Working Reinforcement 22 Hoop reinforcement 24 Radial inner working layer 26 Radial outer working layer 28 Hoop Layer 30 Sidewall 31 Exterior 32 Bead 33 Radial outer end of outer surface of bead 34 Carcass reinforcement 36 Carcass layer / First carcass layer 38 Tread surface 38 Axial inner circumferential reinforcing element 40 Axial outer circumferential reinforcement element 52 First circumferential cut 54 Second circumferential cut 56 3rd circumferential cut 58 4th circumferential cut 62 First center rib 64 Second center rib 66 Third center rib 68 First side rib 70 Second side rib 80 waveforms 90 Sidewall Insert 92 Hard elastomer composition 94 Radially outer end of sidewall insert 96 Radially inner end of sidewall insert 161 Axial end of crown reinforcement 162 Axial end of crown reinforcement 521 Outer end of the first circumferential cut 522 Inner end of first circumferential cut 541 Outer end of second circumferential cut 542 Inner end of second circumferential cut 561 Outer end of the third circumferential cut 562 Inner end of the third circumferential cut 581 Outer end of 4th circumferential cut 582 Inner end of 4th circumferential cut 824 Radially Inner Working Layer Top 826 Top of radially outer working layer 828 Top of hoop layer 844 Radial inner working layer 1 / 2 bottom 846 Radial outer working layer 1 / 2 bottom 848 Hoop layer 1st / 2nd bottom E Tire Equator Ha1~4 1st~4th circumferential cutting depth L Axial width of crown reinforcement La1~4 Axial width of 1st to 4th circumferential cuts Lf1-3 Axial width of the corrugated crown layer separating the first and second bottoms of the corrugations L0 Axial width equal to 80% of axial width L1 Axial width equal to 10% of axial width L2 Axial width equal to 10% of axial width M Median surface of tire N1 A straight line perpendicular to the inner surface and passing through the outer ends of each axial direction of the hoop layer N2 A straight line perpendicular to the inner surface and passing through the radially outer end of the outer surface of each bead P0 Central part of crown reinforcement P1 Side of crown reinforcement P2 Crown reinforcement side X Circumferential direction of the tire Y Axial direction of the tire Z radial direction of the tire

Claims

1. A tire (10) not suitable for runflat, comprising a crown block (12), two beads (32), and two sidewalls (30) connecting each of the beads (32) to the crown block (12), The crown block (12) comprises a tread (14) and a crown reinforcement (16) arranged radially inward of the tread (14), the crown reinforcement (16) having an axial width (L0) equal to 80% of the axial width (L) of the crown reinforcement (16) and a central portion (P0) axially centered on the median plane (M) of the tire (10), the crown reinforcement (16) comprising a small layer called a corrugated crown layer, which comprises reinforcing elements embedded in a polymer matrix. at least one crown layer (24, 26, 28), wherein the corrugated crown layer (24, 26, 28) comprises at least one wave (80) in the central portion (P0) of the crown reinforcement (16), and the or each wave (80) of the corrugated crown layer (24, 26, 28) comprises a peak (824, 826, 828) of the corrugated crown layer and first and second bottom portions (844, 846, 848) of the corrugated crown layer adjacent to the peak (824, 826, 828); - said top portions (824, 826, 828) are axially arranged between said first and second bottom portions (844, 846, 848); said top portions (824, 826, 828) are arranged radially outward of each of said first and second bottom portions (844, 846, 848); It is arranged as follows: the tire (10) comprises a sidewall insert (90) axially disposed between at least one outer surface (31) of the sidewall (30) and the inner surface (19) of the sidewall (30), the sidewall insert (90) comprising at least one elastomer composition (92) called hard elastomer composition, the or each hard elastomer composition (92) of the sidewall insert (90) having a modulus at 10% elongation (MA10) of at least 6 MPa, the maximum thickness (Emax) of the hard elastomer composition (92) or of the assembly of hard elastomer compositions being at most 5.0 mm, A tire (10) characterized by:

2. 2. The tire (10) of claim 1, wherein the tread (14) comprises at least one rib (62, 64, 66) and first and second notches (52, 54, 56, 58) adjacent to the rib, and wherein the crests (824, 826, 828) of the corrugations (80) of the corrugated crown layer are aligned with the rib (62, 64, 66), and each of the first and second bottoms (844, 846, 848) of the corrugations (80) of the corrugated crown layer is aligned with each of the first and second notches (52, 54, 56, 58) adjacent the rib (62, 64, 66), respectively.

3. 2. The tire of claim 1, wherein the tread comprises a plurality of ribs and a plurality of notches, each rib of the plurality of ribs having first and second notches adjacent thereto, the corrugated crown layer comprising a plurality of corrugations in the central portion of the crown reinforcement, the crest of each of the corrugations in the corrugated crown layer being aligned with one of the ribs, and the first and second bottoms of each of the corrugations in the corrugated crown layer being aligned with the first and second notches adjacent thereto, respectively.

4. 2. A tyre (10) according to claim 1, wherein the or each hard elastomeric composition (92) has a modulus at 10% elongation (MA10) of less than or equal to 20 MPa.

5. 2. Tire (10) according to claim 1, wherein the maximum thickness (Emax) of the hard elastomeric composition (92) or of the mass of hard elastomeric compositions is in the range of 1.0 mm to 3.5 mm.

6. the or each sidewall (30) has a minimum thickness (Emin) at a point I, the thickness of the sidewall at a point on the inner surface (19) being defined as the straight-line distance, along a normal (N) to the inner surface (19) at said point on the inner surface (19), between said point on the inner surface (19) and a point on the outer surface (31) of the tire aligned with said point on the inner surface along the normal (N); The point (97) on the inner surface (19) where the thickness of the hard elastomer composition (92) or the mass of hard elastomer composition is greatest is: - a radially outer straight line formed by a normal (N3) to said inner surface (19) passing through a point (93) on said inner surface (19) located 10 mm radially outside point I; a radially inner straight line formed by a normal (N4) to the inner surface (19) passing through a point (95) on the inner surface (19) located 10 mm radially inside point I; and arranged radially between A tire (10) according to claim 1.

7. 2. The tire (10) of claim 1, wherein the thickness of the hard elastomeric composition (92) or mass of hard elastomeric compositions is greatest radially outward of the equator (E) of the tire.

8. The tire (10) of claim 1, wherein a radially outer end (94) of the sidewall insert (90) is disposed radially outward of an equator (E) of the tire.

9. The tire (10) of claim 1, wherein a radially inner end (96) of the sidewall insert (90) is disposed radially inward of an equator (E) of the tire.

10. 2. The tire (10) according to claim 1, wherein the crown reinforcement (16) comprises a working reinforcement (20) comprising at least one working layer (24, 26) and one hoop reinforcement (22) comprising at least one hoop layer (28), the hoop reinforcement (22) being arranged radially outward of the working reinforcement (20), the or each hoop layer (28) comprising at least one corrugation (80) in the central portion (P0) of the crown reinforcement (16).

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