A tire with two carcass layers.

Abstract

A passenger vehicle tire (11) includes a crown (12), two beads (32), two sidewalls (30), each connecting one bead (32) to the crown (12), and a carcass reinforcement (34) fixed to each bead (32). The tire (11) has a load index LI, where LI>LI'+1, and LI' is the load index of an EXTRA LOAD tire of the same size in accordance with the ETRTO Standards Manual (2019). The tire (11) has a sidewall height H, defined as H=SW×AR / 100, where SW is the nominal section width of the tire and AR is the nominal aspect ratio of the tire, in accordance with the ETRTO Standards Manual (2019), of 95 or greater. The carcass reinforcement (34) includes first and second carcass layers (36, 37).

Description

Technical Field

[0001] The present invention relates to a tire, an attachment assembly including such a tire, and a vehicle including such a tire or such an attachment assembly. A tire is understood to mean an enclosure intended to cooperate with a support element of an attachment assembly to form a cavity that can be pressurized to a pressure exceeding atmospheric pressure. The attachment assembly according to the present invention has a substantially toroidal shape structure that exhibits rotational symmetry with respect to the main axis of the attachment assembly that coincides with the main axis of the tire.

Background Art

[0002] The development of electric vehicles or hybrid vehicles has caused an increase in vehicle weight, especially due to relatively heavy batteries that are substantially proportional to the vehicle's range. Thus, for example, in order to increase the range of an electric vehicle, it is necessary to increase the size of the battery, and as a result, the weight of the vehicle increases.

[0003] Briefly stated, today it is estimated that for every 1 kilometer increase in the range of an electric motor, the vehicle weight increases by 1 kilogram. Therefore, in order to achieve a range of 500 km, it is necessary to increase the weight of an internal combustion engine vehicle by about 500 kg. In order to equip such a vehicle, it is necessary to use tires that can withstand very high loads.

[0004] Traditionally, passenger car tires capable of withstanding relatively high loads have been known. These tires are sold under the MICHELIN® brand name as the Pilot Sport 4 series, and come in size 255 / 35R18. This tire has an EXTRA LOAD (abbreviated as XL) version, as defined in the ETRTO standard manual (2019), which has a load index equivalent to 94. This means the tire can withstand a load of 670 kg at a pressure of 290 kPa. This load capacity is relatively higher than that of a tire of the same size called STANDARD LOAD (abbreviated as SL), which has a load index equivalent to 90 and can withstand a load of 600 kg at a pressure of 250 kPa.

[0005] In order to bring such tires to market, they must pass regulatory tests. For example, in Europe, tires must pass the load / speed performance tests described in Annex VII of UN / ECE Regulation 30.

[0006] However, in the EXTRA LOAD version, and even more so in the STANDARD LOAD version, such tires cannot withstand the extra load required to accommodate the battery necessary to achieve the desired driving range. Therefore, tire manufacturers need to propose new solutions to meet this new need.

[0007] One solution that tire manufacturers consider is to use tires that are larger in size for a given vehicle, and thus capable of withstanding greater loads. In this way, a given vehicle can be fitted with tires that have a higher load index. For example, a vehicle fitted with the aforementioned tires in the EXTRA LOAD version can be fitted with EXTRA LOAD version size 275 / 35R19 tires, which have a load index equal to 100 and can withstand a load of 800 kg at a pressure of 290 kPa, which is much larger than a load of 670 kg.

[0008] Such an increase in tire size inevitably leads to either a reduction in the vehicle's internal space or an increase in its external bulk, both of which are undesirable from the standpoint of storage capacity and compactness.

[0009] Furthermore, such an increase in tire size would require a redesign of the vehicle chassis, which is undesirable for obvious cost reasons.

[0010] Finally, increasing tire size, particularly nominal cross-sectional width, is accompanied by increased external noise generated by the tires and increased rolling resistance, which is also undesirable in order to reduce noise pollution and vehicle energy consumption.

[0011] For example, another solution a tire manufacturer might consider is to increase the recommended tire pressure for a given size and version of tire. This is because higher pressure allows the tire to withstand heavier loads.

[0012] However, using relatively high recommended tire pressures can make the tires stiff, compromising passenger comfort, which is clearly undesirable for some automakers when passenger comfort takes precedence over load capacity.

[0013] Another problem tire manufacturers encounter is the relatively high tension in the carcass reinforcement of tires with relatively tall sidewalls, and this tension increases even more as the load capacity increases. [Overview of the Initiative] [Problems that the invention aims to solve]

[0014] The object of the present invention is to provide a tire that can withstand greater loads than existing tires without necessarily increasing the recommended tire pressure, while still being able to control the tension of the tire carcass reinforcement without sacrificing storage capacity, compactness, and comfort. [Means for solving the problem]

[0015] Accordingly, the subject of the present invention is a passenger car tire comprising a crown, two beads, two sidewalls, each connecting each bead to the crown, and a carcass reinforcement fixed to each bead, wherein the crown comprises a crown reinforcement and a tread, and the carcass reinforcement extends within each sidewall and within the crown radially inward of the crown reinforcement. The tire has a load index LI such that LI>LI'+1, where LI' is the load index of an EXTRA LOAD tire of the same size according to the ETRTO standard manual (2019). The tire, in accordance with the ETRTO standard manual (2019), has a sidewall height H defined as H = SW × AR / 100, where SW is the nominal section width and AR is the nominal aspect ratio of the tire, and H ≥ 95. The carcass reinforcement comprises a first and a second carcass layer.

[0016] According to the present invention, the tire is a tire for a passenger car. Such a tire is specified, for example, in the ETRTO (European Tire and Rim Technology Organization) Standards Manual (2019). Such a tire generally has a marking on at least one sidewall indicating the tire size in the form X / YαVUβ in accordance with the markings in the ETRTO Standards Manual (2019), where X specifies the nominal section width, Y specifies the nominal aspect ratio, α specifies the structure and is R or ZR, V specifies the nominal rim diameter, U specifies the load index, and β specifies the speed rating.

[0017] The load index LI' is the load index of tires of the same size, i.e., the same nominal section width, the same nominal aspect ratio, the same construction (R and ZR are considered identical), and the same nominal rim diameter. The load index LI' is given in the ETRTO Standards Manual (2019), specifically in the section titled "Passenger car tires - Metric specified tires," pages 20-41.

[0018] By increasing the load index of the tire according to the present invention compared to the load index of a tire of the same size in the EXTRA LOAD version, the present invention can enhance the load-bearing capacity of the mounting assembly without altering the capacity, compactness, and comfort of the vehicle in which it is used. This is because, since the size of the tire according to the present invention is the same as the size of the tire in the EXTRA LOAD version, the mounting assembly does not take up more space than the tire in the EXTRA LOAD version. The tire according to the present invention may be marked with distinctive markings, such as type HL (HIGH LOAD) or XL+ (EXTRA LOAD+), to distinguish it from the STANDARD LOAD version and the EXTRA LOAD version. Such markings are disclosed, in particular, on page 3 of the "General Notes - Passenger Car Tires" section of the ETRTO Standard Manual (2021) to specify high load capacity tires. Examples of sizes are also disclosed on page 44 of the ETRTO Standard Manual (2021), paragraph 9.1 of the "Passenger Car Tires - Metric Specification" section.

[0019] As explained above, tires with relatively high sidewall heights result in relatively high tension in the carcass reinforcements, particularly the portions of the carcass reinforcements fixed to the bead by folding around circumferential reinforcing elements such as bead wires. This is due to the relatively large volume of expansion gas they contain compared to tires with relatively low sidewall heights. This tension increases with increasing load, which is the case for tires with a load index LI according to the present invention. Therefore, it is essential to use two carcass layers, thereby significantly reducing the tension in each carcass layer.

[0020] Furthermore, in contrast to tires with relatively short sidewalls, i.e., H < 95, the tires according to the invention exhibit a relatively low compression of the carcass reinforcement due to their relatively large height. Therefore, even though there are two carcass layers, the risk of premature degradation of the carcass reinforcement, especially under high loads and at relatively low pressures, is avoided.

[0021] Each of the first and second carcass layers is axially delimited by two axial edges of each of the first and second carcass layers, and comprises a carcass fibrous reinforcing element extending axially from one axial edge to the other axial edge of each of the first and second carcass layers.

[0022] The nominal section width SW and the nominal aspect ratio AR are indicated by size markings engraved on the sidewall of the tire in accordance with the ETRTO standard manual (2019).

[0023] The tire according to the invention has an annular shape around a rotational symmetry axis that substantially coincides with the rotational axis of the tire. This rotational symmetry axis defines the three directions conventionally used by those skilled in the art: the axial direction, the circumferential direction, and the radial direction.

[0024] The axial direction is understood to be a direction substantially parallel to the rotational symmetry axis of the tire or the mounting assembly, i.e., the rotational axis of the tire or the mounting assembly.

[0025] The circumferential direction is understood to be a direction substantially perpendicular to both the axial direction and the radius of the tire or the mounting assembly (in other words, tangent to the circle around the rotational axis of the tire or the mounting assembly).

[0026] The radial direction is understood to be a direction along the radius of the tire or the mounting assembly, i.e., any direction intersecting the rotational axis of the tire or the mounting assembly and substantially perpendicular to that axis.

[0027] The median plane (indicated by M) of the tire is understood to be a plane perpendicular to the tire's axis of rotation that is located axially midway between the two beads and passes through the axial center of the crown reinforcement.

[0028] The equatorial circumferential surface of the tire is understood to be a plane perpendicular to the median plane and the radial direction in the meridian cross-section that passes through the equator of the tire. The equator of the tire is parallel to the axis of rotation of the tire in the meridian cross-section (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), and is an axis that is equidistant between the radially outermost point of the tread intended to contact the ground and the radially innermost point of the tire intended to contact a support, such as a rim.

[0029] The meridian plane is understood to be a plane parallel to and including the axis of rotation of the tire or mounting assembly and perpendicular to the circumferential direction.

[0030] "Inside the radial direction of ~" and "outside the radial direction of ~" are understood to mean "closer to the axis of rotation of the tire than ~" and "farther from the axis of rotation of the tire than ~", respectively. "Inside the axial direction of ~" and "outside the axial direction of ~" are understood to mean "closer to the median plane of the tire than ~" and "farther from the median plane of the tire than ~", respectively.

[0031] The bead is understood to be the part of the tire intended to be able to attach the tire to a mounting support, such as a wheel equipped with a rim. Thus, each bead is particularly intended to contact the flange of the rim that enables attachment to the rim.

[0032] The range of values indicated by the expression "between a and b" represents a range of values that extends from greater than a to less than b (i.e., excluding the endpoints a and b), whereas the range of values indicated by the expression "from a to b" means a range of values that extends from a to b (i.e., including the exact endpoints a and b).

[0033] Preferably, each first and second carcass layer extends within each sidewall and extends radially inside the crown reinforcement within the crown.

[0034] In a discretionary but still advantageous embodiment, H≧100.

[0035] In one advantageous embodiment, LI'+1 ≤ LI ≤ LI'+4, preferably LI'+2 ≤ LI ≤ LI'+4. Therefore, the load-bearing capacity of the tire is further enhanced.

[0036] Optionally, each first and second carcass layer is axially separated by two axial edges of the carcass layer and comprises carcass fabric fibrous reinforcing elements that extend axially from one axial edge to the other, forming an angle with the circumferential direction of the tire and the principal direction, which is in the range of 80° to 90° in absolute terms.

[0037] A fibrous element is understood to be an element whose length is at least 10 times greater than the maximum dimension of its cross-section, regardless of whether it is circular, elliptical, rectangular, polygonal, or especially rectangular, square, or oval. In the case of a rectangular cross-section, the fibrous element takes the form of a strip.

[0038] A fabric is understood to mean a fibrous element comprising one or more fabric-based monofilaments optionally coated with one or more coating layers based on an adhesive composition. These fabric-based monofilaments are obtained, for example, by melt spinning, solution spinning, or gel spinning. Each fabric-based monofilament is made from an organic material, particularly a polymer material, or an inorganic material, such as glass or carbon. Polymer materials can be thermoplastic types, such as aliphatic polyamides, particularly polyamide 6,6, and polyesters, particularly polyethylene terephthalate. Polymer materials can be non-thermoplastic types, such as aromatic polyamides, particularly aramid, and natural or artificial cellulose, particularly rayon.

[0039] In a preferred embodiment, one of the first and second carcass layers forms a winding around each bead's circumferential reinforcing element, such that the axially inner portion of the carcass layer is positioned axially inward of the axially outer portion of the carcass layer, and each axial end of the carcass layer is positioned radially outward of each circumferential reinforcing element.

[0040] In certain preferred configurations, regardless of the sidewall height, each axial end of the carcass layer forming the winding is positioned radially inward from the tire equator, and more preferably within a radial distance of 30 mm or less from the radially inward end of each circumferential reinforcing element of each bead.

[0041] By positioning each axial end of the wound carcass layer inside the tire's equator, the mass of the carcass reinforcement is significantly reduced. Furthermore, most rims currently used in passenger car tires have a J-shaped flange with a height of less than 30 mm in all cases. The highly favorable placement of each axial end within a region substantially radially corresponding to the rim flange allows for mechanical protection of each axial end. This is because if each axial end is positioned too far radially above each circumferential reinforcement element of each bead, i.e., at a radial distance of exactly 30 mm from the radially inner end of each circumferential reinforcement element, it will be in a flexible region of the tire that is subjected to excessively large stresses, and these stresses are very high in the case of high load capacity tires.

[0042] In a preferred first configuration that accommodates the presence of first and second carcass layers, the first carcass layer forms a winding around each circumferential reinforcing element of each bead, the axially inner portion of the first carcass layer is positioned axially inward of the axially outer portion of the first carcass layer, and each axial end of the first carcass layer is positioned radially outward of each circumferential reinforcing element, and each axial end of the second carcass layer is positioned radially inward of each axial end of the first layer. - Between the axially inner and axially outer portions of the first carcass layer in the axial direction, -In the axial direction, on the inside of the axially inner portion of the first carcass layer, Preferably, each axial end of the second carcass layer is positioned axially between the axially inner and outer portions of the first carcass layer.

[0043] This arrangement of the first and second carcass layers makes it possible to achieve an effective mechanical bond between the first and second carcass layers, thereby reducing the shear stress between them. Consequently, energy dissipation and temperature rise of the tire are reduced, especially when shear stress is particularly large under high loads.

[0044] In fact, this arrangement of carcass reinforcements is particularly advantageous when 95 ≤ H ≤ 155. This is because restricting the tire sidewall height to a sidewall height H such that 95 ≤ H ≤ 155 reduces the volume of gas, and consequently, the tension of the carcass reinforcements is reduced to a reasonable level.

[0045] Furthermore, a specific arrangement of the first and second carcass layers surprisingly yields a tire with optimal energy dissipation in the sidewall and operating temperature, especially under high loads and at pressures below the recommended pressure for tires of the same size in STANDARD LOAD or EXTRA LOAD versions. This is surprising because the specific arrangement of the first and second carcass layers is located in one region of the tire, in this case within or near the bead, thereby reducing energy dissipation in another region of the tire away from the bead, in this case the sidewall. It has been found that a specific arrangement of the carcass reinforcements, namely, that each axial end of the second carcass layer is positioned axially between the axially inner and outer portions of the first carcass layer, or axially inside the axially inner portion of the first carcass layer, can reduce the tension difference between the first and second carcass layers. In fact, the smaller the difference in tension between the first and second carcass layers, the smaller the shear stress between them, and the less energy is dissipated.

[0046] In a second configuration adapted to the presence of first and second carcass layers, the first carcass layer forms a winding around each circumferential reinforcing element of each bead, the axially inner portion of the first carcass layer is positioned inside the axially outer portion of the first carcass layer in the axial direction, and each axial end of the first carcass layer is positioned outside each circumferential reinforcing element in the radial direction, and each axial end of the second carcass layer is positioned inside each axial end of the first layer in the radial direction and outside each axially outer portion of the first carcass layer in the axial direction.

[0047] This second configuration is particularly advantageous when H > 155. This is because, in high-load capacity tires with very high sidewall heights such as H > 155, the tension at the ends of the first carcass layer becomes very high. Therefore, unlike the arrangement described in the first configuration, each axial end of the second carcass layer is positioned outside the axial outer portions of the first carcass layer in the axial direction. This arrangement of the carcass reinforcement reduces the tension at the ends of the first carcass layer to a reasonable level.

[0048] In the case of high-load capacity tires with very high sidewall heights, i.e., H>155, even if the tension difference between the first and second carcass layers remains large, the sidewall height allows for a relatively large shear area that effectively dissipates energy. In such tires, the arrangement of the first and second carcass layers described in the first configuration is undesirable.

[0049] Each carcass fabric fibrous reinforcing element preferably comprises an aggregate of at least two multifilament plies having a total count of 475 tex or less.

[0050] This is because the presence of two carcass layers allows for a reduction in the total number of thread counts of the fibrous reinforcing elements in each carcass layer, while still maintaining a carcass reinforcement with sufficient mechanical strength.

[0051] Optionally, each carcass fabric fibrous reinforcing element of each first and second carcass layer has an average diameter D1, D2 such that D1 ≤ 0.90 mm and D2 ≤ 0.90 mm, preferably D1 ≤ 0.85 mm and D2 ≤ 0.85 mm, and more preferably D1 ≤ 0.75 mm and D2 ≤ 0.75 mm.

[0052] These relatively small diameters D1 and D2 make it possible to suppress the occurrence of cracks near the edges of each first and second carcass layer. This is because the edges of each carcass fabric fibrous reinforcing element are prone to cracking, specifically because the element lacks some adhesive composition and, as a result, does not adhere well to the adjacent base material into which it is embedded. By reducing the diameters D1 and D2, the surface area of ​​the edges is reduced, and as a result, the risk of cracking is lowered. Similarly, D1 and D2 are optional, D1 ≥ 0.55 mm and D2 ≥ 0.55 mm, preferably D1 ≥ 0.60 mm and D2 ≥ 0.60 mm.

[0053] The yarn count (or linear density) of each ply and fibrous reinforcing element is determined in accordance with ASTM standard D885 / D885M-10a (2014). The yarn count is given in tex units (weight in grams per 1000 m of product (for note), 0.111 tex is equal to 1 denier).

[0054] The diameter of each carcass fabric fibrous reinforcing element is the diameter of the smallest circle that circumscribes the carcass fabric fibrous reinforcing element. The average diameter is the average value of the diameters of the carcass fabric fibrous reinforcing elements positioned along a 10 cm length of each carcass layer.

[0055] Each multifilament ply is selected from among polyester multifilament plies, aromatic polyamide multifilament plies, and aliphatic polyamide multifilament plies, and is preferably selected from among polyester multifilament plies and aromatic polyamide multifilament plies.

[0056] A polyester multifilament ply is understood to be a multifilament ply composed of monofilaments of linear macromolecules formed by groups linked by ester bonds. Polyesters are produced by polycondensation through esterification of a dicarboxylic acid or one of its derivatives with a diol. For example, polyethylene terephthalate can be produced by polycondensation of terephthalic acid and ethylene glycol. Known polyesters include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polypropylene terephthalate (PPT), or polypropylene naphthalate (PPN).

[0057] Aromatic polyamide multifilament plies are understood to be multifilament plies composed of monofilaments of linear macromolecules formed by aromatic groups linked by amide bonds, with at least 85% directly bonded to two aromatic rings. Poly(p-phenylene terephthalamide) (or PPTA) fibers, in particular, have been produced from optically anisotropic spun compositions for a very long time. Among aromatic polyamides, examples include polyallylamide (or PAA, specifically known by trade name Ixef from Solvay), poly(metaxylylene adipamide), polyphthalamide (or PPA, specifically known by trade name Amodel from Solvay), amorphous semi-aromatic polyamide (or PA6-3T, specifically known by trade name Trogamid from Evonik), or para-aramid (or poly-paraphenylene terephthalamide or PA PPD-T, specifically known by trade name Kevlar from DuPont de Nemours or Twaron from Teijin).

[0058] Aliphatic polyamide multifilament plies are understood to be monofilaments of linear macromolecules of polymers or copolymers that contain amide groups and lack aromatic rings, and can be synthesized by polycondensation of carboxylic acids and amines. Examples of aliphatic polyamides include nylon PA4, 6, PA6, PA6, 6 or PA6, 10, and more specifically, Zytel from Dupont, Technyl from Solvay, or Rilsamid from Arkema.

[0059] More preferably, the aggregate is selected from an aggregate of two polyester multifilament plies, and an aggregate of a polyester multifilament ply and an aromatic polyamide multifilament ply.

[0060] In a preferred embodiment, the tire has a nominal section width SW in the range of 225 to 315, a nominal aspect ratio in the range of 25 to 55, a nominal rim diameter in the range of 18 to 23, and a load index LI in the range of 98 to 116, preferably a nominal section width SW in the range of 245 to 315, a nominal aspect ratio in the range of 30 to 45, a nominal rim diameter in the range of 18 to 23, and a load index LI in the range of 98 to 116. As described above, the tire according to the present invention is intended to support relatively high loads, which inevitably leads to relatively severe wear compared to an EXTRA LOAD version of the same size tire. Therefore, it is particularly advantageous to use a tire with a relatively large nominal section width to reduce the pressure applied to the tread, and consequently reduce wear.

[0061] Advantageously, 0.88 ≤ H / LI ≤ 0.98. Therefore, the present invention is preferably applied to tires that are expected to have relatively large deflection, since these tires have a relatively high load index for a given sidewall height, i.e., satisfy H / LI ≤ 0.98. This is made possible by a specific arrangement of carcass reinforcements, which reduces energy dissipation despite large sidewall deflection. However, if the sidewall is too short for the load index, i.e., satisfy H / LI < 0.88, the sidewall deflection results in relatively high compression of the first carcass layer, resulting in increased energy dissipation.

[0062] A particularly preferred embodiment is one in which the tire has a size and load index LI selected from the following sizes and load indices: 225 / 55R18 105, 225 / 55ZR18 105, 205 / 55R19 100, 205 / 55ZR19 100, 235 / 45R21 104, 235 / 45ZR21 104, 285 / 45R22 116, 285 / 45ZR22 116, 245 / 40R19 101, 245 / 40ZR19 101, 255 / 40R20 104, 255 / 40ZR20 104, 245 / 40R21 103, 245 / 40ZR21 103, 255 / 40R21 105, 255 / 40ZR21 105, 265 / 40R21 108, 265 / 40ZR21 108, 255 / 40R22 106, 255 / 40ZR22 106, 275 / 35R21 105, 275 / 35ZR21 105, 285 / 35R21 108, 285 / 35ZR21 108, 295 / 35R22 111, 295 / 35ZR22 111, 275 / 35R23 108, 275 / 35ZR23 108, 325 / 30R21 111, 325 / 30ZR21 111.

[0063] In some embodiments, the crown reinforcement comprises a working reinforcement including a radially inner working layer and a radially outer working layer positioned radially outside the radially inner working layer.

[0064] In some embodiments, each working layer is axially separated by two axial edges of the working layer and comprises working fibrous reinforcing elements that extend substantially parallel to each other in the axial direction from one axial edge of the working layer to the other axial edge of the working layer.

[0065] Optionally, each working fibrous reinforcing element extends along the circumferential direction of the tire and along the principal direction, which forms an angle in absolute value that is strictly greater than 10°, preferably in the range of 15° to 50°, and more preferably in the range of 20° to 35°.

[0066] Preferably, in an embodiment in which the working reinforcement comprises a radially innermost working layer and a radially outermost working layer positioned radially outside the radially innermost working layer, the main direction in which each working fibrous reinforcing element of the radially innermost working layer extends and the main direction in which each working fibrous reinforcing element of the radially outermost working layer extends form opposite angles with respect to the circumferential direction of the tire.

[0067] Optionally, the crown reinforcement comprises a hoop reinforcement, the hoop reinforcement comprising at least one hooping fibrous reinforcing element that is axially divided by two axial edges and spirally wound circumferentially between each axial edge so as to extend axially.

[0068] Preferably, the hoop reinforcement is positioned radially outward from the working reinforcement.

[0069] Preferably, the hooping fibrous reinforcing element or each of the hooping fibrous reinforcing elements extends along a principal direction that forms an angle with the circumferential direction of the tire of 10° or less in absolute terms, preferably 7° or less, and more preferably 5° or less.

[0070] Further subject matter of the present invention is - Mounting support with rim, - The tire specified above that is mounted on the rim, It is a mounting assembly that includes [a specific feature].

[0071] Advantageously, the crown reinforcement is positioned radially between the tread and the carcass reinforcement and comprises a working reinforcement including at least one axially narrowest working layer, the axially narrowest working layer having an axial width T2 expressed in millimeters, and the rim having a rim width A expressed in millimeters in accordance with the ETRTO standard manual (2019), then the ratio T2 / A is T2 / A ≤ 1.00.

[0072] To control energy dissipation and temperature within the structure during operation of the tire according to the present invention, it is preferable to ensure that the axial width of the narrowest working layer in the axial direction is the correct size relative to the rim width. This is because, under loads exceeding those known from the prior art, the deflection of the tire, i.e., the difference between the radius of the mounting assembly under no load and the radius of the mounting assembly under load, increases considerably. This increase in deflection results in relatively high energy dissipation and a relatively large temperature rise in the tire structure, particularly in the bead.

[0073] To control this, it is preferable to straighten the tire's sidewall, i.e., make the sidewall more radially straight, with the aim of increasing the tire's radial stiffness and avoiding excessive tire deflection, energy dissipation within the tire's structure, and increased temperature. Therefore, -With respect to a given rim width A, the axial width T2 of the narrowest working layer in the axial direction is reduced, thereby reducing the width of the contact patch, and as a result the tire sidewall becomes straight in the radial direction. - With respect to the axial width T2 of the narrowest working layer in the given axial direction, increase the rim width A so that the tire sidewall remains straight in the radial direction. It is recommended to reduce the ratio T2 / A to a value of 1.00 or less.

[0074] When a person skilled in the art changes the axial width T2 of the narrowest working layer in the axial direction, they will adapt the characteristics of the tire crown, in particular the characteristics of the crown reinforcement comprising the working reinforcement and either hoop reinforcement, and the characteristics of the tread as a function of the axial width T2 that they will determine.

[0075] In both cases, the radial stiffness of the tire increases, resulting in a reduction in tire deflection under a given load, thereby at least partially offsetting the effects of the increased load. Consequently, the stress on the tire structure decreases, and therefore energy dissipation and temperature rise during tire operation also decrease.

[0076] To minimize the increase in rotating mass on the vehicle, and to improve vehicle load capacity and compactness by reducing the space occupied by the mounting assembly, it is prioritized to reduce the axial width T2 of the narrowest working layer in the axial direction rather than increasing the rim width A. The axial width of the narrowest working layer in the axial direction is measured in the tire cross-section in the meridional plane and corresponds to the axial width between the two axial ends of the working layer.

[0077] Preferably, the narrowest working layer in the axial direction is the radially outer working layer of the working reinforcement.

[0078] In similarly advantageous embodiments, 0.85 ≤ T2 / A, preferably 0.90 ≤ T2 / A, and more preferably 0.93 ≤ T2 / A ≤ 0.97.

[0079] The ratio T2 / A is preferably not excessively small. Specifically, it is preferable not to make the axial width T2 of the narrowest working layer in the axial direction excessively small with respect to a given rim width A, because otherwise the bending stiffness along the edge, and consequently the cornering stiffness during large turns, will decrease. Furthermore, if the axial width T2 of the narrowest working layer in the axial direction becomes too small, the width of the contact patch decreases, thereby increasing the pressure applied to the tread and consequently increasing wear. This wear is amplified because the tire according to the present invention is intended to support relatively high loads, inevitably leading to severe wear, more severe than that of the same-sized tire in an EXTRA LOAD version which is required to support small loads in all cases. As explained above, it is also preferable not to make the rim width A too large for the axial width T2 of the narrowest working layer in the axial direction, not only in order to suppress the increase in mass rotating on the vehicle, but also in order to reduce the space occupied by the mounting assembly and promote the vehicle's capacity and compactness.

[0080] In a preferred embodiment, the tire has a nominal cross-sectional width SW such that T2 ≥ SW-75, preferably T2 ≥ SW-70. With respect to a given nominal cross-sectional width, the axially narrowest working layer, which mainly defines the width of the contact patch, is not too small. In fact, as described above, this makes it possible to maintain good wear performance of the tire despite it being intended to support relatively high loads that inevitably result in relatively severe wear.

[0081] In a preferred embodiment, the tire has a nominal cross-sectional width SW such that T2 ≤ SW - 27, preferably T2 ≤ SW - 30.

[0082] In these embodiments, as is generally the case with the present invention, the nominal section width is the width indicated by the size marking engraved on the tire sidewall.

[0083] To reduce the risk of mounting a tire on a rim with a width that is too small and results in a relatively high degree of curvature at the tire's shoulder, it becomes a priority to limit the rims that can be used with the tire. Therefore, the rims are selected from the following: - The rim width code is equal to the standard measuring rim width code for the tire size, and the rim is defined in accordance with the ETRTO standard manual (2019). - Rims whose rim width code is equal to the standard rim width code for the tire size minus 0.5, and - A rim whose rim width code is equal to the standard rim width code for the tire size plus 0.5.

[0084] The measuring rim is specified in particular on pages 20 to 41 of the section "Passenger car tires - Metric specified tires" in the ETRTO Standards Manual (2019).

[0085] In order to suppress the increase in rotating mass on the vehicle, as well as to reduce the space occupied by the mounting assembly and promote the vehicle's capacity and compactness, it is preferable that the rim has a rim width code equal to the standard rim width code for the tire size minus 0.5.

[0086] Advantageously, tires inflate to a pressure ranging from 200 kPa to 350 kPa, preferably between 250 kPa and 330 kPa. This pressure is the pressure of the mounting assembly at 25°C when the tire is not being driven. This often corresponds to one of the air pressures recommended by the car manufacturer.

[0087] In applications where prioritizing the load-bearing capacity of tires is desired, relatively high pressures of 270 kPa or higher are used.

[0088] In applications where occupant comfort and vehicle behavior, particularly grip on dry ground, are prioritized, relatively low pressures of 270 kPa or less are used.

[0089] A further application of the present invention is a passenger car having at least one tire or mounting assembly as defined above. The present invention can be better understood by referring to the drawings and reading the following description, which is given merely as a non-limiting example. [Brief explanation of the drawing]

[0090] [Figure 1] This is a meridional cross-sectional view of a mounting assembly according to the first embodiment of the present invention. [Figure 2] Figure 1 is a meridional cross-sectional view of the tire of the mounting assembly. [Figure 3] This is a cross-sectional view along plane III-III' in Figure 2, showing the carcass reinforcement of the tire in Figure 1. [Figure 4] This figure is similar to Figure 1, comparing the deflection of the mounting assembly of the prior art with the deflection of the mounting assembly in Figure 1. [Modes for carrying out the invention]

[0091] Each figure shows the reference frame X, Y, and Z corresponding to the normal axial (Y), radial (Z), and circumferential (X) directions of the tire, respectively.

[0092] The following description uses measurements taken for unloaded, uninflated tires, or for portions of the tire within the meridional plane.

[0093] Figure 1 shows a mounting assembly according to the present invention, which is represented as a whole by reference no. 10. The mounting assembly 10 comprises a tire 11 and a mounting support 100 including a rim 200. The tire 11 inflates to a pressure in the range of 200 kPa to 350 kPa, preferably 250 kPa to 330 kPa, in this case equal to 270 kPa.

[0094] The tire 11 has a substantially annular shape around a rotationally symmetric axis R that is substantially parallel to the axial direction Y. The tire 11 is intended for passenger cars. In various figures, the tire 11 is depicted as new, i.e., as unused.

[0095] The tire 11 comprises two sidewalls 30 having markings indicating the size of the tire 11, as well as a speed rating and speed code. In this example, the tire 11 is in the range of 225 to 315, preferably in the range of 245 to 315, and here has a nominal section width SW equal to 225. The tire 11 also has a nominal aspect ratio AR in the range of 25 to 55, here equal to 55. The tire 11 has a nominal rim diameter in the range of 18 to 23, here equal to 18. Thus, the tire 11 has a sidewall height H = 124 ≥ 95, preferably H ≥ 100, defined as SW × AR / 100.

[0096] According to the present invention, the marking also includes a load index LI in the range of 98 to 116, such that LI ≥ LI'+1, where LI' is the load index of an EXTRA LOAD tire of the same size in accordance with the ETRTO Standard Manual (2019). Preferably, LI'+1 ≤ LI ≤ LI'+4, and even more preferably LI'+2 ≤ LI ≤ LI'+4.

[0097] A 225 / 55R18 tire in the EXTRA LOAD version has a load index equal to 102, as shown on page 28 of the "Passenger Car Tyres - Tyres with Metric Designation" section of the ETRTO Standard Manual (2019). Therefore, the load index LI of tire 11 is such that LI ≥ 103, preferably 103 ≤ LI ≤ 106, and even more preferably 104 ≤ LI ≤ 106, in which case LI = 105. This load index equal to 105 corresponds to the load index of a high load capacity tire of size 225 / 55R18 as shown in the ETRTO Manual (2021). Therefore, tire 11 is clearly a high load capacity type.

[0098] For this size, the ETRTO standard manual (2019), on page 28 of the section "Passenger car tires - Metric specified tires," indicates a standard rim with a rim width code equal to 7. Therefore, the rim 200 of the mounting assembly 10 is selected from the following: - The rim width code is equal to the standard rim width code for the tire size, and the rim is defined in accordance with the ETRTO standard manual (2019). - Rims whose rim width code is equal to the standard rim width code for the tire size minus 0.5, and - A rim whose rim width code is equal to the standard rim width code for the tire size plus 0.5.

[0099] In this case, the rim 200 of the mounting assembly 10 is a rim whose rim width code is equal to the standard rim width code for the tire size minus 0.5, and therefore equal to 6.5 in this case. The rim 200 has a type J outer shape and rim width A in accordance with the ETRTO standard manual (2019). In this example, since the outer shape of the rim 200 is type 6.5J, its rim width A, expressed in mm, is equal to 165.10 mm.

[0100] Referring to Figure 2, the tire 11 comprises a crown 12, which includes a tread 14 intended to contact the ground during driving, and a crown reinforcement 16 extending circumferentially X within the crown 12. The tire 11 also comprises an airtight layer 18 against expansion gas, which is intended to define an internal cavity with respect to the tire 11 that is closed by the mounting support 100 once the tire 11 is mounted to the mounting support 100.

[0101] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22. 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 located radially inside it. Of the radially inner layer 24 and the radially outer layer 26, the radially outer layer 26 is the narrowest in the axial direction.

[0102] The hoop reinforcement 22 comprises at least one hooping layer, in this case, one hooping layer 28.

[0103] The crown reinforcement 16 has the tread 14 mounted on it in the radial direction. In this case, the hoop reinforcement 22, in this example the hooping layer 28, is positioned radially outside the working reinforcement 20 and is therefore inserted radially between the working reinforcement 20 and the tread 14.

[0104] The two sidewalls 30 extend the crown 12 radially inward. The tire 10 also has two beads 32 radially inward of the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown 12.

[0105] The tire 11 includes a carcass reinforcement 34, which is fixed to each bead 32 and in this example forms a winding around a circumferential reinforcing element 33. The carcass reinforcement 34 extends radially in each sidewall 30, axially in the crown 12, and radially inward of the crown reinforcement 16. The crown reinforcement 16 is positioned radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass layer 36, in this case comprising first and second carcass layers 36, 37. The first and second carcass layers 36, 37 extend within each sidewall 30 and radially inward of the crown reinforcement 16 within the crown 12.

[0106] The hoop reinforcement 22, in this example the hooping layer 28, is separated by two axial edges 281 and 282 and comprises one or more hooping fibrous reinforcing elements, which are spirally wound circumferentially between the axial edges 281 and 282 along the main direction which forms an angle AF of 10° or less, preferably 7° or less, and more preferably 5° or less in absolute value, with respect to the circumferential direction X of the tire 10. In this case, AF = -5°.

[0107] Each radially inner working layer 24 and radially outer working layer 26 are axially separated by two axial edges 241, 242, 261, and 262 of each working layer 24 and 26, respectively. The radially inner working layer 24 has an axial width T1 = 174.00 mm, and the radially outer working layer 26 has an axial width T2 = 160.00 mm, making the radially outer working layer 26 the narrowest working layer in the axial direction.

[0108] It should be noted that SW=225 and T2=160 satisfy the following relationships: T2≧SW-75, preferably T2≧SW-70, and T2≦SW-27, preferably T2≦SW-30.

[0109] As shown in Figure 1, the mounting assembly 10 is such that the tire 11 has a radially straight sidewall. Specifically, the ratio T2 / A is such that 0.85 ≤ T2 / A ≤ 1.00, preferably 0.90 ≤ T2 / A ≤ 1.00, and more preferably 0.93 ≤ T2 / A ≤ 0.97, in which case T2 / A = 0.97.

[0110] Each working layer 24, 26 is provided with working fibrous reinforcing elements that extend substantially parallel to each other along the principal direction, forming opposite angles AT1 and AT2, respectively, from one axial edge 241, 261 to the other axial edge 242, 262, such that the angles are, in absolute value, greater than 10° in the circumferential direction X of the tire 10, preferably in the range of 15° to 50°, more preferably in the range of 20° to 35°. In this case, AT1 = -26° and AT2 = +26°.

[0111] Each of the first and second carcass layers 36 and 37 is axially separated by two axial edges 361, 362, 371, and 372, and each has a carcass fabric fibrous reinforcing element 360 and 370 extending in the main direction D3 forming an angle AC from one axial edge 361 and 371 to the other axial edge 362 and 372, respectively, and this angle is in the range of 80° to 90° in absolute value with respect to the circumferential direction X of the tire 10, in which case AC = +90°.

[0112] The first carcass layer 36 forms a winding around each circumferential reinforcing element 33 of each bead 32 such that the axially inner portions 3611, 3621 of the first carcass layer 36 are positioned inside the axially outer portions 3612, 3622 of the first carcass layer 36 in the axial direction, and the axial ends 361, 362 of the first carcass layer 36 are positioned outside the circumferential reinforcing elements 33 in the radial direction. The axial ends 371, 372 of the second carcass layer 37 are positioned radially inside the axial edges 361, 362 of the first carcass layer, and are positioned axially between the axially inner portions 3611, 3621 and the axially outer portions 3612, 3622 of the first carcass layer 36.

[0113] Each axial end 361, 362 of the first carcass layer 36 is positioned radially inward from the tire's equator E. More specifically, each axial end 361, 362 of the first carcass layer 36 is positioned at a radial distance RNC of 30 mm or less from the radially inward end 331 of each circumferential reinforcing element 33 of each bead 32. In this case, RNC = 23 mm.

[0114] Each working layer 24, 26, hooping layer 28, and carcass layer 36 comprises a calendered base material for the fibrous reinforcing elements of the corresponding layer. Preferably, the calendered base material is a polymer, more preferably an elastomer, as is commonly used in the field of tires.

[0115] Conventionally, each hooping fibrous reinforcement element comprises two multifilament plies, each multifilament ply composed of a spun yarn of aliphatic polyamide, in this case nylon monofilament, with a count equal to 140 tex. These two multifilament plies are individually twisted spirally at 250 turns per meter, and then twisted together spirally in the opposite direction at 250 turns per meter. These two multifilament plies are then spirally wound around each other. As a variation, a hooping fibrous reinforcement element can be used comprising one multifilament ply composed of a spun yarn of aliphatic polyamide, in this case nylon monofilament, with a count equal to 140 tex, and one multifilament ply composed of an aromatic polyamide, in this case aramid monofilament, with a count equal to 167 tex. These two multifilament plies are individually twisted spirally in one direction at 290 turns per meter, and then twisted spirally in the opposite direction at 290 turns per meter. These two multifilament plies are spirally wound around each other. In yet another variant, a hooping fibrous reinforcing element can be used, comprising two multifilament plies, each composed of spun monofilament yarn of aromatic polyamide, in this case aramid, with a count equal to 330 tex, and one multifilament ply, each composed of spun monofilament yarn of aliphatic polyamide, in this case nylon, with a count equal to 188 tex, each of which is individually spirally twisted in one direction at 270 turns per meter, and then spirally twisted in the opposite direction at 270 turns per meter. These two multifilament plies are spirally wound around each other.

[0116] Generally, the use of high loads leads to a decrease in the tire's permissible speed limit and a reduction in its behavior, such as cornering stiffness. Therefore, by using one or more highly elastic hooping fibrous reinforcing elements, such as those described in the last two variations above which include one or more aromatic polyamide strands, it is possible to increase the tire's permissible speed limit and improve its behavior, particularly its cornering stiffness.

[0117] Each working fibrous reinforcing element is an assembly 4.26 of four steel monofilaments, comprising an inner layer of two monofilaments and an outer layer of two monofilaments spirally wound together around the inner layer, for example, in the S direction at a pitch of 14.0 mm. Such an assembly 4.26 has a breaking force equal to 640 N and a diameter equal to 0.7 mm. Each steel monofilament has a diameter equal to 0.26 mm and a mechanical strength equal to 3250 MPa. As a modified form, it is also possible to use an assembly of six steel monofilaments, having a diameter equal to 0.23 mm and comprising an inner layer of two monofilaments spirally wound together around each other in a first direction, for example in the Z direction at a pitch of 12.5 mm, and an outer layer of four monofilaments spirally wound around the inner layer in a second direction opposite to the first direction, for example in the S direction at a pitch of 12.5 mm.

[0118] As shown in Figure 3, each of the first and second carcass layers 36 and 37, each of the carcass fabric fibrous reinforcing elements 360 and 370 comprises an assembly of at least two multifilament plies 363, 364 and 373 and 374. Each multifilament ply 363, 364, 373 and 374 is selected from polyester multifilament plies, aromatic polyamide multifilament plies, and aliphatic polyamide multifilament plies, preferably selected from polyester multifilament plies and aromatic polyamide multifilament plies. In this example, the assembly is selected from an assembly of two polyester multifilament plies, and an assembly of one polyester multifilament ply and one aromatic polyamide multifilament ply, which in this example consists of two PET multifilament plies, these two multifilament plies are individually spirally twisted in one direction at 420 turns per meter, and then spirally twisted in the opposite direction at 420 turns per meter. Since each of these multifilament plies has a count equal to 114 tex, the total count of the aggregate is 475 tex or less, which in this case is equal to 228 tex.

[0119] Each carcass fabric fibrous reinforcing element 360, 370 has average diameters D1 and D2 such that, when expressed in mm, D1 ≤ 0.90 mm and D2 ≤ 0.90 mm, preferably D1 ≤ 0.85 mm and D2 ≤ 0.85 mm, more preferably D1 ≤ 0.75 mm and D2 ≤ 0.75 mm, and D1 ≥ 0.55 mm and D2 ≥ 0.55 mm, preferably D1 ≥ 0.60 mm and D2 ≥ 0.60 mm. In this case, D1 = D2 = 0.62 mm.

[0120] Here, a tire according to a second embodiment of the present invention will be described.

[0121] In contrast to the first embodiment, the tire according to the second embodiment has a nominal section width SW equal to 255, a nominal aspect ratio AR equal to 40, a nominal rim diameter equal to 21, and a sidewall height H=102 defined as SW×AR / 100, which is 95 or greater. A tire of size 225 / 40R21 in the EXTRA LOAD version has a load index equal to 102, as shown on page 34 of the "Passenger Car Tyres - Tyres with Metric Designation" section of the ETRTO Standards Manual (2019). Thus, the load index LI of the tire according to the second embodiment is such that LI≧103, preferably 103≦LI≦106, and even more preferably 104≦LI≦106, in which case LI=105. This load index equal to 105 corresponds to the load index of a high load capacity tire of size 225 / 40R21 as shown in the ETRTO manual (2021). Therefore, the tire according to the second embodiment is indeed a high load capacity type.

[0122] Unlike the tire according to the first embodiment, the tire according to the second embodiment satisfies 0.88 ≤ H / LI ≤ 0.98, in which case H / LI = 0.97.

[0123] Official Exam

[0124] Tension simulation

[0125] To demonstrate the advantages of the present invention, the inventors simulated the tension of each fibrous reinforcing element in the carcass of multiple tires.

[0126] For each of these tests, the tension of each carcass fibrous reinforcing element was simulated for a tire inflated to a pressure equivalent to 2.8 bar, subjecting it to a load far greater than that used in the load / speed performance tests described in Annex VII of UN / ECE Regulation 30.

[0127] We simulated various tires of the following sizes: 255 / 35R20, 235 / 60R18, and 255 / 60R18, as follows: - The tire has a carcass reinforcement comprising first and second carcass layers according to the present invention (represented by reference numbers INV1 and INV2), wherein each axial end of the second carcass layer is positioned radially inward of each axial end of the first layer and is positioned axially between the axially inward and axially outward portions of the first carcass layer (first configuration), - The tire has a carcass reinforcement comprising first and second carcass layers according to the present invention (represented by reference numbers INV1' and INV2'), wherein each axial end of the second carcass layer is positioned radially inward of each axial end of the first layer and axially outward of each axially outward portion of the first carcass layer (second configuration), - The tire has carcass reinforcements similar to those of tires INV1 and INV2, but the sidewall height H is strictly less than 95 (COMP0), and - The tire has a single carcass reinforcement (COMP1, COMP2) and the sidewall height H is strictly less than 95 (COMP0').

[0128] The tension of each carcass fibrous reinforcing element is measured at the edge of the single carcass layer for tires with a single carcass layer, and at the edge of the first carcass layer that forms a winding around the circumferential reinforcing element of each bead for tires with two carcass layers.

[0129] The results of these simulations are summarized in Table 1 below. [Table 1]

[0130] First, it has been shown that in the case of a tire having first and second carcass layers, the tension of the carcass fibrous reinforcing elements is significantly reduced compared to a tire having a single carcass layer. Thus, the tension of the carcass reinforcing elements is controlled by the use of first and second carcass layers.

[0131] Furthermore, it turns out that this control over the tension of the carcass reinforcement is only necessary for tires with a sidewall height of 95 or more. This is because the tension of the carcass reinforcement in tires with a sidewall height of exactly less than 95 remains controlled, even in the case of carcass reinforcement with a single carcass layer.

[0132] Furthermore, it should be noted that for a given number of carcass layers, the tension increases as the sidewall height increases. Therefore, if it is desirable to reduce the tension of the carcass reinforcement to a reasonable level with the arrangement of carcass reinforcement according to the first configuration, the sidewall height will be controlled to a value of 155 or less. If the sidewall height is strictly greater than 155, the arrangement of carcass reinforcement according to the second configuration will be prioritized to reduce this tension, as explained above.

[0133] Driving test simulation

[0134] To demonstrate the optional advantages of the arrangement of carcass reinforcements in the first configuration over the second configuration for tires with sidewall heights of 155 mm or less, the inventors simulated tire running.

[0135] For each of these tests, a run similar to the load / speed performance test described in Annex VII of UN / ECE Regulation No. 30 was simulated under more severe load and pressure conditions. Various tire sizes, 255 / 40R21, 235 / 60R18, and 255 / 60R18, were simulated as follows: - The tire has an arrangement of carcass reinforcements according to the first configuration (represented by INV1, INV2, and INV3), - The tire features a carcass reinforcement arrangement according to a second configuration (represented by INV1', INV2', and INV3').

[0136] During these simulations, the maximum volumetric energy dissipation DNRJ was recorded for a portion of the calendered base material of the first and second carcass layers, which is located on the sidewall between the first and second carcass layers in the axial direction, and daN / mm 2 The values ​​are expressed in units. The higher this value, the greater the energy dissipation due to the tire structure, and the greater the temperature rise. The results of these simulations are summarized in Table 2 below. [Table 2]

[0137] It should be noted that the arrangement of carcass reinforcements according to the first configuration is advantageous for reducing energy dissipation, while the arrangement of carcass reinforcements according to the second configuration does not reduce energy dissipation to the same extent. This is particularly advantageous when the sidewall height H ≤ 130, preferably H ≤ 120, and more preferably H ≤ 110. This is because, at such sidewall heights, the maximum volumetric energy dissipation DNRJ is relatively high, and the use of the carcass reinforcement arrangement according to the first configuration makes it possible to significantly reduce energy dissipation to an acceptable level in absolute terms.

[0138] Even if, in absolute terms, energy dissipation is smaller when the sidewall height exceeds 130 than when it is 130 or less, the arrangement of the carcass reinforcement in the first configuration still makes it possible to reduce this energy dissipation by approximately 50%.

[0139] Static testing

[0140] To illustrate the effect of straightening the sidewall, which is advantageous but optional within the scope of the present invention, Figure 4 shows the results of a static compression test on a tire of size 225 / 55R18, which is identical to the tire described above, but with a ratio T2 / A equal to 1.05 (tire shown on the left) and a ratio T2 / A equal to 0.97 (tire shown on the right). The load applied to each tire was equal to 925 kg at a pressure of 250 kPa.

[0141] Note that the deflection of the left tire is much greater than that of the right tire. This is because the distance DR1 from the axis of rotation R to the ground for the left tire is smaller than the distance DR2 from the axis of rotation R to the ground for the right tire.

[0142] In particular, note that the sidewall of the right tire is straighter radially than the sidewall of the left tire. This can be seen by comparing the distances DF1 and DF2 at the same radial point on each sidewall, between the outer surface of the sidewall opposite the contact surface and the plane SA that is perpendicular to the tire's axis of rotation R and passes through the rim's support surface that defines the axial width A of the rim. This can also be seen by comparing the distances DF1' and DF2' between the outer surface of the sidewall and the perpendicular plane SA at the same radial point on each sidewall located parallel to the contact surface. It will be observed that DF1 > DF2 and DF1' > DF2'.

[0143] The present invention is not limited to the embodiments described above.

Claims

1. A passenger car tire (11) comprising a crown (12), two beads (32), two sidewalls (30) connecting each of the beads (32) to the crown (12), and a carcass reinforcement (34) fixed to each of the beads (32), wherein the crown (12) comprises a crown reinforcement (16) and a tread (14), and the carcass reinforcement (34) extends within each of the sidewalls (30) and extends radially inward of the crown reinforcement (16) within the crown (12), The tire (11) has a load index LI such that LI > LI' + 1, where LI' is the load index of an EXTRA LOAD tire of the same size in accordance with the ETRTO standard manual (2019), The tire (11) has a sidewall height H defined as H = SW × AR / 100, where SW is the nominal section width of the tire and AR is the nominal aspect ratio of the tire, in accordance with the ETRTO standard manual (2019), and H ≥ 95. The carcass reinforcement (34) comprises first and second carcass layers (36, 37), One of the first and second carcass layers (36, 37) forms a winding around each of the circumferential reinforcing elements (33) of the bead, the axially inner portion (3611, 3621) of the first carcass layer (36) is positioned axially inside the axially outer portion (3612, 3622) of the carcass layer (36), and each of the axial ends (361, 362) of the carcass layer (36) is positioned radially outside each of the circumferential reinforcing elements (33). Each of the axial ends (361, 362) of the carcass layer (36) forming the winding is positioned at a radial distance RNC of 30 mm or less from the radial inner end (331) of each circumferential reinforcing element (33) of each bead (32). A tire (11) characterized by the following.

2. LI'+1 ≤ LI ≤ LI'+4 The tire (11) according to claim 1.

3. Each of the first and second carcass layers (36, 37) is axially separated by two axial ends (361, 362, 371, 372) of the carcass layer (36, 37), and includes carcass fabric fibrous reinforcing elements (360, 370) that extend axially from one axial end to the other of the carcass layer (36, 37) in the circumferential direction (X) of the tire (11) and in the principal direction, forming an angle in the range of 80° to 90° in absolute value. The tire (11) according to claim 1 or 2.

4. 95 ≤ H ≤ 155, the first carcass layer (36) forms a winding around each of the circumferential reinforcing elements (33) of the bead, the axially inner portion (3611, 3621) of the first carcass layer (36) is positioned inside the axially outer portion (3612, 3622) in the axial direction, each of the axial ends (361, 362) of the first carcass layer is positioned outside each of the circumferential reinforcing elements (33) in the radial direction, and each of the axial ends (371, 372) of the second carcass layer (37) is positioned inside each of the axial ends (361, 362) of the first carcass layer (36) in the radial direction, and - Between the axial inner portion (3611, 3621) and the axial outer portion (3612, 3622) of the first carcass layer (36) in the axial direction, or - Displaced in the axial direction inside the axial inner portion (3611, 3621) of the first carcass layer (36), A tire (11) according to any one of claims 1 to 3.

5. H > 155, the first carcass layer (36) forms a winding around each of the circumferential reinforcing elements (33) of the bead, the axially inner portion (3611, 3621) of the first carcass layer (36) is positioned axially inside the axially outer portion (3612, 3622) of the first carcass layer (36), the axial ends (361, 362) of the first carcass layer (36) are positioned radially outside each of the circumferential reinforcing elements (33), and each of the axial ends (371, 372) of the second carcass layer (37) is positioned radially inside the axial ends (361, 362) of the first carcass layer (36) and axially outside each of the axially outer portion (3612, 3622) of the first carcass layer (36). A tire (11) according to any one of claims 1 to 4.

6. It has a nominal section width SW in the range of 245 to 315, a nominal aspect ratio in the range of 30 to 45, a nominal rim diameter in the range of 18 to 23, and a load index LI in the range of 98 to 116. A tire (11) according to any one of claims 1 to 5.

7. 0.88 ≤ H / LI ≤ 0.98 A tire (11) according to any one of claims 1 to 6.

8. The following sizes and load indices are available: 225 / 55R18 105, 225 / 55ZR18 105, 205 / 55R19 100, 205 / 55ZR19 100, 235 / 45R21 104, 235 / 45ZR21 104, 285 / 45R22 116, 285 / 45ZR22 116, 245 / 40R19 101, 245 / 40ZR19 101, 255 / 40R20 104, 255 / 40ZR20 104, 245 / 40R21 103, 245 / 40ZR21 103, 255 / 40R21 105, 255 / 40ZR21 105, 265 / 40R21 108, 265 / 40ZR21 108, 255 / 40R22 106, 255 / 40ZR22 106, 275 / 35R21 105, 275 / 35ZR21 105, 285 / 35R21 108, 285 / 35ZR21 108, 295 / 35R22 111, 295 / 35ZR22 111, 275 / 35R23 108, 275 / 35ZR23 108, 325 / 30R21 111, 325 / 30ZR21 Having sizes and load index LI selected from 111, A tire (11) according to any one of claims 1 to 7.

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