MINI WHEEL TIRES

Description

[0001] The present invention relates to a tire. By tire is meant a bandage intended to form a cavity by cooperating with a mounting support, this cavity being capable of being pressurized to a pressure higher than atmospheric pressure. A tire according to the invention has a structure of substantially toroidal shape of revolution around a main axis of the tire.

[0002] The advent of electric or hybrid passenger vehicles leads to an increase in the weight of vehicles, particularly due to the batteries, whose weight is relatively high and significantly proportional to the vehicles' range. For example, to increase the range of an electric vehicle, it is necessary to increase the size of the batteries and, consequently, the weight of the vehicle.

[0003] Simply put, it is estimated today that one kilometer of electric motor range increases the vehicle's weight by one kilogram. Thus, to achieve a range of 500 kilometers, it is necessary to increase the weight of a thermal engine vehicle by approximately 500 kg. To equip such vehicles, it is necessary to use tires capable of carrying a very high load.

[0004] A passenger vehicle tire is known from the state of the art, this tire being capable of carrying a relatively high load. This tire is marketed under the MICHELIN ™< brand in the Pilot Sport 4 range and has a size 255 / 35R18. This tire has an EXTRA-LOAD version (abbreviated XL) within the meaning of the ETRTO 2019 standard manual and, in this EXTRA-LOAD version, has a load index equal to 94. This means that, at a pressure of 290 kPa, the tire is capable of carrying a load of 670 kg. This load capacity is relatively high compared to a tire of the same size and qualified as STANDARD LOAD (abbreviated SL) with a load index equal to 90 and which is capable of carrying a load of 600 kg at a pressure of 250 kPa.

[0005] In order to be placed on the market, such a tire must meet regulatory tests. For example, in Europe, the tire must meet the load / speed performance test described in Annex VII of UNECE Regulation No. 30.

[0006] However, whether in its EXTRA-LOAD version, or even more so in its STANDARD LOAD version, such a tire is not capable of carrying the extra charge corresponding to the batteries needed to achieve the desired autonomy. Thus, tire manufacturers have had to come up with new solutions to meet this new need.

[0007] One solution being considered by tire manufacturers is, for a given vehicle, the use of larger tires, which would allow it to carry more load. Thus, a given vehicle could be equipped with tires with a higher load index. For example, a vehicle equipped with the tires described above in their EXTRA LOAD version could be equipped with tires of size 275 / 35R19 in their EXTRA-LOAD version, which have a load index equal to 100 and are capable, at a pressure of 290 kPa, of carrying a load of 800 kg, much higher than the load of 670 kg.

[0008] On the one hand, such an increase in the size of the tires necessarily leads either to a reduction in the interior space of the vehicle, or to an increase in the exterior dimensions of the vehicle, which, in both cases, is not desirable for reasons of habitability and compactness of the vehicle.

[0009] On the other hand, such an increase in tire size requires a new design of the vehicle chassis, which, for obvious cost reasons, is also not desirable.

[0010] Finally, such an increase in the size of the tires, particularly the nominal section width, leads to an increase in the external noise generated by the tire as well as an increase in rolling resistance, which is also not desirable if we want to reduce noise pollution and the energy consumption of the vehicle.

[0011] Thus, another solution considered by tire manufacturers is, for a given size and a given version of a tire, to increase its inflation pressure. Indeed, the higher the pressure, the more the tire is capable of carrying a high load.

[0012] However, using a relatively high pressure stiffens the tire and leads to a loss of comfort for the vehicle's passengers, which is obviously not desired by some car manufacturers in cases where passenger comfort takes priority over the load that can be carried.

[0013] Another problem encountered by manufacturers when developing a tire is the dissipation of energy and the temperature in the structure, which can be highlighted in particular in the test described in Annex VII of UNECE Regulation No. 30. Indeed, by increasing the load applied to a tire in order to simulate the addition of a corresponding mass to the batteries necessary to obtain the desired autonomy, a significant increase in energy dissipation and a rise in temperature were observed both in the bead and in the shoulder of the tire.

[0014] The state of the art of the tires described in EP1201462, EP0812708 and "Reifen-Ratgeber 2020-2021 PkW 4x4 Van" (continental) is known.

[0015] The invention aims to provide a tire capable of carrying a greater load than existing tires without necessarily involving an increase in tire pressure while controlling energy dissipation and temperature rise in the tire structure without sacrificing the habitability, compactness and comfort of the vehicle.

[0016] Thus, the subject of the invention is a passenger vehicle tire comprising a crown, two beads, two sidewalls each connecting each bead to the crown and a carcass reinforcement anchored in each bead, the crown comprising a crown reinforcement and a tread, the carcass reinforcement extending in each sidewall and in the crown radially inside the crown reinforcement, the crown reinforcement being arranged radially between the tread and the carcass reinforcement and comprising a working reinforcement comprising at least one axially narrowest working layer, the axially narrowest working layer having an axial width T2 expressed in mm,the tire being suitable for mounting on a mounting support comprising a rim the tire having a load index LI such that LI ≥ LI'+1 and LI' being the load index of an EXTRA LOAD tire having the same dimension according to the ETRTO 2019 standard manual, and when the tire is mounted on a rim having a rim width code equal to the width code of the measuring rim for the tire dimension and defined according to the ETRTO 2019 standard manual reduced by 0.5, the ratio T2 / A is such that T2 / A ≤ 1.00 with A being the rim width A according to the ETRTO 2019 standard manual, and expressed in mm of the rim..,

[0017] According to the invention, the tire is a passenger vehicle tire. Such a tire is for example defined in the ETRTO 2019 (European Tire and Rim Technical Organization) standard manual. Such a tire has, generally on at least one of the sidewalls, a marking in accordance with the marking in the ETRTO 2019 standard manual indicating the tire dimension in the form X / Y α VU β with X designating the nominal section width, Y designating the nominal aspect ratio, α designating the structure and possibly being R or ZR, V designating the nominal rim diameter, U designating the load index and β designating the speed symbol.

[0018] The LI' load index is the load index of a tyre with the same dimension, i.e. the same nominal section width, the same nominal aspect ratio, the same structure (R and ZR being considered identical) and the same nominal rim diameter. The LI' load index is given by the ETRTO 2019 standard manual, in particular in the Part entitled Passenger Car Tyres - Tyres with Metric Designation, pages 20 to 41.

[0019] The axial width of the axially narrowest working layer is measured on a tire section in a meridian plane and corresponds to the width in the axial direction between the two axial ends of the working layer.

[0020] By increasing the load index of the tire of the invention compared to the load index of a tire having the same dimension in its EXTRA-LOAD version, the invention makes it possible to increase the load capacity of the mounted assembly comprising the tire according to the invention and the mounting support without modifying the habitability, compactness and comfort of the vehicle on which it is used. Indeed, the dimension of the tire according to the invention being identical to that of the tire in its EXTRA-LOAD version, the tire does not take up more space than the tire in its EXTRA-LOAD version. A tire according to the invention may bear a distinctive marking making it possible to distinguish it from its STANDARD LOAD version and its EXTRA-LOAD version, for example a marking of the HL (for HIGH LOAD) or XL+ (for EXTRA LOAD +) type.Such marking is disclosed in particular in the ETRTO 2021 standard manual, page 3 of the section General Notes - Passenger Car tyres to designate HIGH LOAD CAPACITY type tyres. Examples of dimensions are also disclosed in the ETRTO 2021 standard manual, page 44, paragraph 9.1 of the section Passenger Car tyres - Tyres with metric designation.

[0021] However, in order to control the energy dissipation and the temperature in the structure during operation of the tire according to the invention, it is necessary to correctly dimension the axial width of the axially narrowest working layer relative to the width of the rim. Indeed, the inventors behind the invention discovered that, in the case of a high load beyond that known from the state of the art, the deflection of the tire, that is to say the difference between the radius of the assembled assembly in the absence of load and the radius of the assembled assembly under this load, was considerably increased. This increase in the deflection leads to relatively significant energy dissipation and a rise in temperature in the structure of the tire, particularly in the bead.

[0022] In order to control this, the invention proposes to rectify the sidewall of the tire, that is to say to make the sidewall straighter in the radial direction, with the aim of increasing the radial rigidity of the tire to avoid excessive bending of the tire and the increase in energy dissipation and temperature in the structure of the tire. The invention recommends reducing the T2 / A ratio to a value less than or equal to 1.00 in order to: for a given rim width A, to reduce the axial width T2 of the axially narrowest working layer which results in a reduction in the width of the contact patch and therefore a radial rectification of the tire sidewall, for a given axial width T2 of the axially narrowest working layer to increase the rim width A which also results in a radial rectification of the tire sidewall.

[0023] In the case where the person skilled in the art varies the axial width T2 of the axially narrowest working layer, the person skilled in the art will adapt the characteristics of the crown of the tire, in particular those of the crown reinforcement comprising the working reinforcement and a possible hoop reinforcement, as well as those of the tread according to the axial width T2 that he will have determined.

[0024] In both cases, the radial rigidity of the tire is increased, therefore reducing the deflection of the tire for a given load, which makes it possible to at least partially compensate for the impact of the increased load and thus reduce the stresses exerted on the structure of the tire and therefore the dissipation of energy and the rise in temperature during operation of the tire.

[0025] In order to limit the increase in rotating masses on the vehicle but also to reduce the size of the mounted assembly to promote the habitability and compactness of the vehicle, it will be preferred to reduce the axial width T2 of the axially narrowest working layer rather than increasing the rim width A. Thus, the invention requires that the rim has a rim width code equal to the width code of the measuring rim for the tire dimension reduced by 0.5. This limits the increase in rotating masses on the vehicle but also the size of the mounted assembly to promote the habitability and compactness of the vehicle. Finally, thanks to the T2 / A ratio, the risk of seeing the tire mounted on a rim whose rim width would be too small and would cause relatively strong flexion of the tire is reduced.

[0026] The measuring rim is defined in particular on pages 20 to 41 of the Passenger Car Tyres - Tyres with Metric Designation section of the ETRTO 2019 standard manual.

[0027] The tire according to the invention has a substantially toric shape around an axis of revolution substantially coincident with the axis of rotation of the tire. This axis of revolution defines three directions conventionally used by those skilled in the art: an axial direction, a circumferential direction and a radial direction.

[0028] Axial direction means the direction substantially parallel to the axis of revolution of the tire or mounted assembly, i.e. the axis of rotation of the tire or mounted assembly.

[0029] Circumferential direction means the direction which is substantially perpendicular to both the axial direction and a radius of the tire or mounted assembly (in other words, tangent to a circle whose center is on the axis of rotation of the tire or mounted assembly).

[0030] Radial direction means the direction along a radius of the tire or mounted assembly, i.e. any direction intersecting the axis of rotation of the tire or mounted assembly and substantially perpendicular to this axis.

[0031] By median plane of the tire (noted M), we mean the plane perpendicular to the axis of rotation of the tire which is located at the axial midpoint of the two beads and passes through the axial center of the crown reinforcement.

[0032] By equatorial circumferential plane of the tire, we mean, in a meridian section plane, the plane passing through the equator of the tire, perpendicular to the median plane and to the radial direction. The equator of the tire is, in a meridian section plane (plane perpendicular to the circumferential direction and parallel to the radial and axial directions) the axis parallel to the axis of rotation of the tire and located equidistant between the radially outermost point of the tread intended to be in contact with the ground and the radially innermost point of the tire intended to be in contact with a support, for example a rim.

[0033] Meridian plane means a plane parallel to and containing the axis of rotation of the tire or mounted assembly and perpendicular to the circumferential direction.

[0034] By radially inner, respectively radially outer, is meant closer to the tire's axis of rotation, respectively further from the tire's axis of rotation. By axially inner, respectively axially outer, is meant closer to the tire's median plane, respectively further from the tire's median plane.

[0035] By bead is meant the portion of the tire intended to allow the tire to be attached to a mounting support, for example a wheel comprising a rim. Thus, each bead is in particular intended to be in contact with a hook on the rim allowing it to be attached.

[0036] Any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from more than a to less than b (i.e., excluding the limits a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (i.e., including the strict limits a and b).

[0037] In an advantageous embodiment, LI'+1 ≤ LI ≤ LI'+4, preferably LI'+2 ≤ LI ≤ LI'+4. Thus, the loading capacity of the tire is further increased.

[0038] In also advantageous embodiments, 0.85 ≤ T2 / A, preferably 0.90 ≤ T2 / A, and more preferably 0.93 ≤ T2 / A ≤ 0.97.

[0039] It is preferable to have a T2 / A ratio that is not too small. Indeed, for a given rim width A, it is preferable not to reduce too much the value of the axial width T2 of the axially narrowest working layer at the risk of reducing the bending rigidity on the edges and therefore the drift rigidity at high drift. In addition, by reducing too much the value of the axial width T2 of the axially narrowest working layer, the width of the contact patch is reduced, which increases the pressure exerted on the tread and therefore wear, this wear being amplified by the fact that the tires according to the invention are intended to carry relatively high loads necessarily leading to high wear, in any case higher than tires of the same size in their EXTRA LOAD version intended to carry lower loads.For a given axial width T2 of the axially narrowest working layer, it is also preferable not to increase the value of the rim width A too much in order, as explained above, to limit the increase in rotating masses on the vehicle but also to reduce the size of the mounted assembly to promote the habitability and compactness of the vehicle.

[0040] In preferred embodiments, the tire has a nominal section width SW such that T2 ≥ SW - 75, preferably T2 ≥ SW - 70. For a given nominal section width, the axially narrowest working layer which mainly defines the width of the contact patch is not too reduced. Indeed, as explained above, this makes it possible to maintain good wear performance of the tire despite the fact that the tires according to the invention are intended to carry relatively high loads necessarily leading to relatively high wear.

[0041] In preferred embodiments, the tire has a nominal section width SW such that T2 ≤ SW - 27, preferably T2 ≤ SW - 30.

[0042] In these embodiments as in the invention in general, the nominal section width is that of the dimension marking inscribed on the sidewall of the tire.

[0043] In preferred embodiments, the tire has a nominal section width SW ranging from 205 to 315, a nominal aspect ratio ranging from 25 to 55, a nominal rim diameter ranging from 17 to 23 and a load index LI ranging from 98 to 116, preferably a nominal section width SW ranging from 225 to 315, a nominal aspect ratio ranging from 25 to 55, a nominal rim diameter ranging from 18 to 23 and a load index LI ranging from 98 to 116, and more preferably a nominal section width SW ranging from 245 to 315, a nominal aspect ratio ranging from 30 to 45, a nominal rim diameter ranging from 18 to 23 and a load index LI ranging from 98 to 116. As explained above, the tires according to the invention are intended to carry relatively high loads necessarily leading to relatively high wear compared to to tires of the same dimensions in their EXTRA LOAD version.Therefore, it is particularly advantageous to use tires with a relatively high nominal section width in order to reduce the pressure exerted on the tread and therefore wear.

[0044] Advantageously, 0.82≤H / LI≤0.98. Thus, the invention is preferably applied to tires capable of flexing relatively significantly because they have a relatively high load index for a given sidewall height, i.e. satisfying H / LI≤0.98. This is made possible by the T2 / A ratio which makes it possible to reduce energy dissipation despite significant deflection of the sidewall. However, if the sidewall is too short compared to the load index, i.e. satisfying H / LI<0.82, the flexing of the sidewall leads to relatively significant compression of the carcass reinforcement and therefore an increase in energy dissipation.

[0045] Particularly preferred embodiments are those in which the tire has a size and a load index LI chosen 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, 205 / 40R17 88, 205 / 40ZR17 88, 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, 255 / 35R18 98, 255 / 35ZR18 98, 245 / 35R20 98, 245 / 35ZR20 98, 265 / 35R20 102, 265 / 35ZR20 102, 245 / 35R21 99, 245 / 35ZR21 99, 255 / 35R21 101, 255 / 35ZR21 101, 265 / 35R21 103, 265 / 35ZR21 103, 275 / 35R21 105, 275 / 35ZR21 105, 285 / 35R21 108, 285 / 35ZR21 108, 295 / 35R22 111, 295 / 35ZR22 111, 275 / 35R23 108, 275 / 35ZR23 108, 285 / 30R21 103, 285 / 30ZR21 103, 315 / 30R21 109, 315 / 30ZR21 109, 325 / 30R21 111, 325 / 30ZR21 111, 315 / 30R23 111, 315 / 30ZR23 111.

[0046] Advantageously, when the tire is mounted on the mounting bracket, the tire is inflated to a pressure ranging from 200 to 350 kPa, preferably from 250 to 330 kPa. The pressure is that of the assembled assembly at 25°C without the tire having been driven. It often corresponds to one of the inflation pressures recommended by car manufacturers.

[0047] In applications where the load capacity of the tire is to be prioritized, a relatively high pressure greater than or equal to 270 kPa will be used.

[0048] In applications where passenger comfort and vehicle handling are to be prioritized, particularly grip on dry ground, a relatively low pressure of less than or equal to 270 kPa will be used.

[0049] In embodiments, the working reinforcement comprises a radially inner working layer and a radially outer working layer arranged radially outside the radially inner working layer.

[0050] Preferably, the axially narrowest working layer is the radially outer working layer of the working reinforcement.

[0051] In embodiments, the axially narrowest working layer or each working layer is axially delimited by two axial edges of said working layer and comprises working wire reinforcement elements extending axially from one axial edge to the other axial edge of said working layer substantially parallel to each other.

[0052] Optionally, each working wire reinforcement element extends in a main direction forming, with the circumferential direction of the tire, an angle, in absolute value, strictly greater than 10°, preferably ranging from 15° to 50° and more preferably ranging from 20° to 35°.

[0053] Preferably, in the embodiments in which the working reinforcement comprises a radially innermost working layer and a radially outermost working layer arranged radially outside the radially innermost layer, the main direction in which each working cord reinforcement element of the radially innermost working layer extends and the main direction in which each working cord reinforcement element of the radially outermost working layer extends form, with the circumferential direction of the tire, angles of opposite orientations.

[0054] In embodiments in which the tire has a so-called radial carcass, the carcass reinforcement comprises at least one carcass layer, the or each carcass layer being delimited axially by two axial edges of the or each carcass layer, the or each carcass layer comprises wire carcass reinforcement elements extending axially from one axial edge to the other axial edge of the or each carcass layer.

[0055] In variants, the or each carcass layer comprises textile filamentary carcass reinforcing elements extending axially from one axial edge to the other axial edge of the or each carcass layer in a main direction forming, with the circumferential direction of the tire, an angle ranging, in absolute value, from 80° to 90°.

[0056] A wire element is understood to mean an element having a length at least 10 times greater than the largest dimension of its section, regardless of the shape of the latter: circular, elliptical, oblong, polygonal, in particular rectangular, square or oval. In the case of a rectangular section, the wire element has the shape of a strip.

[0057] Textile means a threaded element comprising one or more elementary textile monofilaments optionally coated with one or more layers of a coating based on an adhesive composition. This or these elementary textile monofilaments is or are obtained, for example, by melt spinning, solution spinning or gel spinning. Each elementary textile monofilament is made of an organic material, in particular polymeric, or inorganic, such as for example glass or carbon. The polymeric materials can be of the thermoplastic type, such as for example aliphatic polyamides, in particular polyamides 6-6, and polyesters, in particular polyethylene terephthalate. The polymeric materials can be of the non-thermoplastic type, such as for example aromatic polyamides, in particular aramid, and cellulose, natural or artificial, in particular rayon.

[0058] In a first embodiment, the carcass reinforcement comprises a single carcass layer.

[0059] Such a carcass reinforcement makes it possible to obtain a tire with optimal energy dissipation and operating temperature, particularly at high load and under a pressure lower than or equal to the pressure recommended for a tire of the same size in its STANDARD LOAD or EXTRA-LOAD version. Indeed, unlike a carcass reinforcement comprising two carcass layers in which the flexion of each sidewall leads to a relatively significant compression of the axially innermost carcass layer in the sidewall and at the shoulder of the tire and an increase in energy dissipation, the single carcass layer has less compression in the sidewall and at the shoulder and therefore leads to a lower and more optimal operating temperature.

[0060] In particular, it is advantageous to control this operating temperature in cases of under-inflation, which are frequently and chronically encountered. Indeed, it is known that under-inflation leads to an increase in the operating temperature of the sidewalls in the case of tires in their STANDARD LOAD or EXTRA-LOAD version. In the case of a HIGH LOAD CAPACITY type tire, under-inflation is even more problematic and leads to an amplified increase in the operating temperature of the sidewalls due to the very high load carried by the tire.

[0061] By single carcass layer is meant that the carcass reinforcement is, with the exception of the carcass layer, devoid of any layer reinforced by wire reinforcement elements. The wire reinforcement elements of such reinforced layers excluded from the carcass reinforcement of the tire include metal wire reinforcement elements and textile wire reinforcement elements. Very preferably, the carcass reinforcement is constituted by the single carcass layer.

[0062] In this first embodiment, optionally, the tire has a sidewall height H defined by H=SW x AR / 100 with SW the nominal section width and AR the nominal aspect ratio of the tire and such that H < 95.

[0063] Tires with a relatively low sidewall height have a relatively high compression of the carcass reinforcement, especially as the load carried is high, which is the case for tires with a load index LI in accordance with the invention. Thus, it is very advantageous to use a single carcass layer in combination with a sidewall height H < 95.

[0064] In certain optional but nevertheless advantageous embodiments, 90 ≤ H < 95. Indeed, these embodiments have relatively high sidewalls in the range of sidewall heights covered by the first embodiment and for which the use of a single carcass layer is particularly advantageous because it makes it possible to significantly reduce the mass of the tire and the rolling resistance compared to a tire comprising two carcass layers.

[0065] In a first variant allowing anchoring of the carcass reinforcement by turning over, the single carcass layer forms a winding around a circumferential reinforcing element of each bead such that an axially inner portion of the single carcass layer is arranged axially inside an axially outer portion of the single carcass layer and such that each axial end of the single carcass layer is arranged radially outside each circumferential reinforcing element.

[0066] In a second variant allowing anchoring of the carcass reinforcement without turning over, the single carcass layer has a portion arranged axially between two circumferential reinforcing elements of each bead and each axial end of the single carcass layer is arranged radially inside each radially outer end of each circumferential reinforcing element of each bead. Such a variant of anchoring of the carcass reinforcement is described for example in documents WO2005 / 113259 or WO2021 / 123522.

[0067] The choice of anchoring for the carcass reinforcement will be made in particular according to the sidewall height H and the LI index. In fact, the lower the sidewall height H and the higher the load index, the more the second anchoring variant will be preferred. In cases where the sidewall height H is high and the load index low, the first or second anchoring variant can be chosen indifferently.

[0068] In the first embodiment, preferably, each textile wire reinforcement element of the carcass comprises an assembly of at least two multifilament strands and having a total count greater than or equal to 475 tex.

[0069] In fact, in order for the single carcass layer to have sufficient mechanical resistance, textile carcass wire reinforcement elements with a relatively high count will be used, which, for a given material, makes it possible to achieve relatively high mechanical resistance.

[0070] Optionally in the first embodiment, each textile wire reinforcement element of the carcass has an average diameter D ≥ 0.85 mm, preferably D ≥ 0.90 mm. Also optionally, D ≤ 1.10 mm, preferably D ≤ 1.00 mm.

[0071] In the first embodiment and for the reasons explained previously, we have even more advantageously 0.82≤H / LI≤0.92.

[0072] In a second embodiment, the carcass reinforcement comprises first and second carcass layers.

[0073] Such a carcass reinforcement makes it possible to obtain a relatively resistant reinforcement, particularly to pinching (in English “Pinch Shock”).

[0074] In this second embodiment, optionally, the tire has a sidewall height H defined by H=SW x AR / 100 with SW the nominal section width and AR the nominal aspect ratio of the tire and such that H ≥ 95, preferably H ≥ 100.

[0075] Tires with a relatively high sidewall height lead to a relatively high tensioning of the carcass reinforcement, in particular of the portion of the carcass reinforcement anchored in the bead, for example by turning around a circumferential reinforcing element such as a bead wire, due to the relatively high volume of inflation gas that they contain in comparison with a tire with a relatively low sidewall height. This tensioning is all the higher as the load carried is high, which is the case for tires with a load index LI in accordance with the invention. Thus, it is very advantageous to use two carcass layers, which makes it possible to significantly reduce the tensioning of each carcass layer.

[0076] Furthermore, unlike the tires according to the first embodiment, the tires having a relatively high sidewall height have a relatively low compression of the carcass reinforcement. The risk of premature deterioration of the carcass reinforcement, particularly under high load and relatively low pressure, is therefore eliminated despite the presence of two carcass layers.

[0077] Preferably, each first and second carcass layer extends in each sidewall and in the crown radially inward of the crown reinforcement.

[0078] In a preferred embodiment, one of the first and second carcass layers forms a wrap around a circumferential reinforcing element of each bead such that an axially inner portion of said carcass layer is arranged axially inside an axially outer portion of said carcass layer and such that each axial end of said carcass layer is arranged radially outside each circumferential reinforcing element.

[0079] In a first preferred configuration compatible with the presence of a first and a second carcass layer: the first carcass layer forms a wrap around a circumferential reinforcing element of each bead such that an axially inner portion of the first carcass layer is arranged axially inside an axially outer portion of the first carcass layer and such that each axial end of the first carcass layer is arranged radially outside each circumferential reinforcing element, and each axial end of the second carcass layer is arranged radially inside each axial end of the first layer and is arranged: 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, and preferably,each axial end of the second carcass layer is arranged axially between the axially inner and outer portions of the first carcass layer.

[0080] Such an arrangement of the first and second carcass layers makes it possible to obtain an effective mechanical coupling between the first and second carcass layers, making it possible to reduce the shear between the first and second carcass layers. This reduces energy dissipation and the rise in temperature of the tire, especially since the shear is particularly high at high loads.

[0081] Indeed, such an arrangement of the carcass reinforcement is particularly advantageous in the case where 95 ≤ H ≤ 155. Indeed, by limiting the sidewall height of the tire to sidewall heights H such that 95 ≤ H ≤ 155, the volume of gas and therefore the tensioning of the carcass reinforcement is reduced to a reasonable level.

[0082] Furthermore, thanks to the particular arrangement of the first and second carcass layers, a tyre with optimum energy dissipation and operating temperature in the sidewall is surprisingly obtained, particularly under heavy load and at a pressure less than or equal to the pressure recommended for a tyre of the same size in its STANDARD LOAD or EXTRA-LOAD version. This is all the more surprising since the particular arrangement of the first and second carcass layers is located in one area of ​​the tyre, here in the bead or close to the bead, and this makes it possible to reduce energy dissipation in another area of ​​the tyre, far from the bead, here the sidewall.It has been discovered that the particular arrangement of the carcass reinforcement, that is to say the fact that each axial end of the second carcass layer is arranged 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, makes it possible to reduce the difference in tensions between the first carcass layer and the second carcass layer. However, the smaller the difference in tensions between the first and second carcass layers, the less shear is generated between these first and second carcass layers and the less energy is dissipated.

[0083] In a second configuration compatible with the presence of a first and a second carcass layer, the first carcass layer forms a wrap around a circumferential reinforcing element of each bead such that an axially inner portion of the first carcass layer is arranged axially inside an axially outer portion of the first carcass layer and such that each axial end of the first carcass layer is arranged radially outside each circumferential reinforcing element, and each axial end of the second carcass layer is arranged radially inside each axial end of the first layer and is arranged axially outside each axially outer portion of the first carcass layer.

[0084] This second configuration is particularly advantageous in the case where H > 155. Indeed, for HIGH LOAD CAPACITY type tires having a very high sidewall height such as H>155, the tension of the end of the first carcass layer becomes very high, it will be necessary to consider a carcass reinforcement in which, unlike the arrangement described in the first configuration, each axial end of the second carcass layer is arranged axially outside each axially outer portion of the first carcass layer. With such an arrangement of the carcass reinforcement, the tension of the end of the first carcass layer will be reduced to a reasonable level.

[0085] For HIGH LOAD CAPACITY type tires with a very high sidewall height, i.e. with H>155, even if the difference in tension between the first carcass layer and the second carcass layer remains high, the sidewall height allows for a relatively large shear zone which dissipates energy efficiently and for which it is not preferable to have the arrangement of the first and second carcass layers described in the first configuration.

[0086] In the second embodiment, preferably, each textile wire reinforcement element of the carcass comprises an assembly of at least two multifilament strands and having a total count less than or equal to 475 tex.

[0087] In fact, the presence of two carcass layers makes it possible to reduce the total title of each textile wire reinforcement element of the carcass of each layer while having sufficient mechanical resistance of the carcass reinforcement.

[0088] Optionally in the second embodiment, each textile wire reinforcement element of the carcass of each first and second carcass layer respectively 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.

[0089] Such relatively small diameters D1 and D2 make it possible to limit the initiation of cracks near the end of each first and second carcass layer. Indeed, the end of each textile wire reinforcement element of the carcass constitutes a preferred starting point for the initiation of cracks, in particular due to the fact that it is devoid of any adhesive composition and therefore has little adhesion to the adjacent matrix in which it is embedded. By reducing each diameter D1, D2, the surface area of ​​the end and therefore the risk of crack initiation is reduced. Also optionally, D1 and D2 are such that D1 ≥ 0.55 mm and D2 ≥ 0.55 mm, preferably D1 ≥ 0.60 mm and D2 ≥ 0.60 mm.

[0090] In the second embodiment and for the reasons explained above, we have even more advantageously 0.88≤H / LI≤0.98.

[0091] Whether in the first or second embodiment, the nominal section width SW and the nominal aspect ratio AR are those of the dimension marking on the sidewall of the tire and comply with the ETRTO 2019 standard manual. The titles (or linear density) of each strand and wire reinforcement element are determined according to the ASTM D 885 / D 885M - 10a standard of 2014. The title is given in tex (weight in grams of 1000 m of product - reminder: 0.111 tex equals 1 denier).

[0092] Whether in the first or second embodiment, the diameter of each carcass textile wire reinforcement element is the diameter of the smallest circle in which the carcass textile wire reinforcement element is circumscribed. The average diameter is the average of the diameters of the carcass textile wire reinforcement elements located over a length of 10 cm of each carcass layer.

[0093] Whether in the first or second embodiment, optionally, each multifilament strand is selected from a polyester multifilament strand, an aromatic polyamide multifilament strand and an aliphatic polyamide multifilament strand, preferably each multifilament strand is selected from a polyester multifilament strand and an aromatic polyamide multifilament strand.

[0094] A polyester multifilament strand is a multifilament strand consisting of monofilaments of linear macromolecules formed from groups linked together by ester bonds. Polyesters are manufactured by polycondensation by esterification between a dicarboxylic acid or one of its derivatives and a diol. For example, polyethylene terephthalate can be manufactured 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).

[0095] By aromatic polyamide multifilament strand is meant a multifilament strand consisting of monofilaments of linear macromolecules formed from aromatic groups linked together by amide bonds of which at least 85% are directly linked to two aromatic nuclei, and more particularly of poly (p-phenylene terephthalamide) (or PPTA) fibers, manufactured for a very long time from optically anisotropic spinning compositions.Aromatic polyamides include polyarylamides (or PAA, known in particular under the trade name Ixef from the Solvay company), poly(metaxylylene adipamide), polyphthalamides (or PPA, known in particular under the trade name Amodel from the Solvay company), amorphous semi-aromatic polyamides (or PA 6-3T, known in particular under the trade name Trogamid from the Evonik company), para-aramids (or poly(paraphenylene terephthalamide or PA PPD-T, known in particular under the trade name Kevlar from the Du Pont de Nemours company or Twaron from the Teijin company).

[0096] By multifilament strand of aliphatic polyamide is meant a multifilament strand consisting of monofilaments of linear macromolecules of polymers or copolymers containing amide functions not having aromatic cycles and which can be synthesized by polycondensation between a carboxylic acid and an amine. Among the aliphatic polyamides, mention may be made of nylons PA4.6, PA6, PA6.6 or PA6.10, and in particular Zytel from the DuPont company, Technyl from the Solvay company or Rilsamid from the Arkema company.

[0097] Very preferably, the assembly is chosen from an assembly of two multifilament strands of polyester and an assembly of one multifilament strand of polyester and one multifilament strand of aromatic polyamide.

[0098] Whether in the first or second embodiment, in certain preferred configurations, each axial end of the wound carcass layer is arranged radially inside the equator of the tire and even more preferably arranged at a radial distance less than or equal to 30 mm from a radially inner end of each circumferential reinforcing element of each bead.

[0099] By arranging each axial end of the wound carcass layer inside the equator of the tire, the mass of the carcass reinforcement is significantly reduced. In addition, the vast majority of rims currently used for passenger vehicle tires have J-type hooks whose height is, in all cases, less than 30 mm. The very preferential arrangement of each axial end in an area corresponding radially substantially to the rim hook makes it possible to mechanically protect each axial end.Indeed, if each axial end were arranged radially too far above each circumferential reinforcing element of each bead, i.e. at a radial distance strictly greater than 30 mm from the radially inner end of each circumferential reinforcing element, each axial end would then find itself in a flexible zone of the tyre subjected to excessive stresses, stresses which are particularly significant in the case of a HIGH LOAD CAPACITY type tyre.

[0100] Optionally, the crown reinforcement comprises a hoop reinforcement axially delimited by two axial edges of the hoop reinforcement and comprising at least one hoop wire reinforcement element wound circumferentially helically so as to extend axially between the axial edges of the hoop reinforcement.

[0101] Preferably, the hoop reinforcement is arranged radially outside the working reinforcement.

[0102] Preferably, the or each hoop wire reinforcement element extends in a main direction forming, with the circumferential direction of the tire, an angle, in absolute value, less than or equal to 10°, preferably less than or equal to 7° and more preferably less than or equal to 5°.

[0103] The invention will be better understood upon reading the following description, given solely as a non-limiting example and with reference to the drawings in which: there figure 1 is a view, in a meridian section plane, of a mounted assembly comprising a tire according to a first embodiment of the invention, the figure 2 is a view, in a meridian section plane, of the tire of the figure 1 , there figure 3 is a sectional view along plane III-III' of the figure 2illustrating the carcass reinforcement of the tire of the figure 1 , THE Figures 4 and 5 are views analogous respectively to the Figures 2 and 3 of a tire according to a second embodiment, and the figure 6 is a view analogous to that of the figure 1 comparing the deflection of a state-of-the-art assembled assembly and that of the assembled assembly of the figure 1 .

[0104] In the figures, a reference X, Y, Z is shown corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions respectively of a tire or a mounted assembly.

[0105] In the following description, the measurements are taken on an unloaded and uninflated tire or on a section of the tire in a meridian plane. PNEUMATIC ACCORDING TO A FIRST METHOD OF IMPLEMENTATION

[0106] It has been represented on the figure 1a mounted assembly designated by the general reference 10. The mounted assembly 10 comprises a tire 11 according to the invention and a mounting support 100 comprising a rim 200. The tire 11 is here inflated to a pressure ranging from 200 to 350 kPa, preferably from 250 to 330 kPa and here equal to 270 kPa.

[0107] The tire 11 has a substantially toric shape around an axis of revolution R substantially parallel to the axial direction Y. The tire 11 is intended for a passenger vehicle. In the various figures, the tire 11 is shown in new condition, that is to say not having yet been driven.

[0108] The tire 11 comprises two sidewalls 30 bearing a marking indicating the size of the tire 11, as well as a speed index and a speed code. In this case, the tire 11 has a nominal section width SW ranging from 205 to 315, preferably from 225 to 315, more preferably ranging from 245 to 315 and here equal to 205. The tire 11 also has a nominal aspect ratio AR ranging from 25 to 55, preferably ranging from 30 to 45 and here equal to 40. The tire 11 has a nominal rim diameter ranging from 17 to 23 and here equal to 17. The tire 11 therefore has a sidewall height H defined by SW x AR / 100 = 82 < 95.

[0109] According to the invention, the marking also comprises a load index LI ranging from 98 to 116, such that LI ≥ LI'+1 with LI' being the load index of an EXTRA LOAD tire having the same dimension according to the ETRTO 2019 standard manual. Preferably, LI'+1 ≤ LI ≤ LI'+4, and even LI'+2 ≤ LI ≤ LI'+4.

[0110] A tire with a dimension 205 / 40R17 in its EXTRA LOAD version has a load index equal to 84 as indicated on page 34 of the Passenger Car Tyres - Tyres with Metric Designation section of the ETRTO 2019 standard manual. Thus, the load index LI of tire 11 is such that LI ≥85, preferably 85 ≤ LI ≤ 88 and even 86 ≤ LI ≤ 88 and here LI=88. This load index equal to 88 corresponds to the load index of a HIGH LOAD CAPACITY tire of dimension 205 / 40R17. Thus, tire 11 is indeed of the HIGH LOAD CAPACITY type.

[0111] The tire 11 is such that 0.82 ≤ H / LI ≤ 0.98 and here H / LI=0.93.

[0112] For such a dimension, the ETRTO 2019 standard manual indicates, on page 34 of the Passenger Car Tyres - Tyres with Metric Designation section, a measuring rim with a rim width code equal to 7.5. The tyre is suitable for mounting on the 200 rim of the mounted assembly 10.

[0113] Here, the 200 rim is the rim with a rim width code equal to the width code of the measuring rim for the tire size reduced by 0.5 and therefore here equal to 7.0. The 200 rim has a profile of type J and a rim width A according to the ETRTO 2019 standard manual. In this case, the profile of the 200 rim being of type 7.0 J, its rim width A expressed in mm is equal to 177.80 mm.

[0114] In reference to the figure 2, the tire 11 comprises a crown 12 comprising a tread 14 intended to come into contact with a ground when rolling and a crown reinforcement 16 extending in the crown 12 in the circumferential direction X. The tire 11 also comprises a sealing layer 18 to an inflation gas being intended to delimit an internal cavity closed with the mounting support 100 of the tire 11 once the tire 11 is mounted on the mounting support 100.

[0115] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22. The working reinforcement 16 comprises at least one working layer and here comprises two working layers including a radially inner working layer 24 arranged radially inside a radially outer working layer 26. Of the two radially inner 24 and radially outer 26 layers, the axially narrower layer is the radially outer layer 26.

[0116] The hoop reinforcement 22 comprises at least one hoop layer and here comprises a hoop layer 28.

[0117] The crown reinforcement 16 is radially surmounted by the tread 14. Here, the hoop reinforcement 22, here the hoop layer 28, is arranged radially outside the working reinforcement 20 and is therefore radially interposed between the working reinforcement 20 and the tread 14.

[0118] The two sidewalls 30 extend the crown 12 radially inwards. The tire 11 further comprises two beads 32 radially inwards to the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown 12.

[0119] The tire 11 comprises a carcass reinforcement 34 anchored in each bead 32, in this case forming a winding around a circumferential reinforcing element 33, here a bead wire. The carcass reinforcement 34 extends radially in each sidewall 30 and axially in the crown 12, radially internal to the crown reinforcement 16. The crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass layer 36 and here a single carcass layer 36.

[0120] The hoop reinforcement 22, here the hoop layer 28, is delimited axially by two axial edges 281, 282 and comprises one or more hoop wire reinforcement elements wound circumferentially helically between each axial edge 281, 282 in a main direction forming, with the circumferential direction X of the tire 10, an angle AF, in absolute value, less than or equal to 10°, preferably less than or equal to 7° and more preferably less than or equal to 5°. Here, AF=-5°.

[0121] Each radially inner 24 and radially outer 26 working layer is axially delimited by two axial edges respectively 241, 242, 261, 262 of each working layer 24, 26. The radially inner working layer 24 has an axial width T1=180.00 mm and the radially outer working layer 26 has an axial width T2=166.00 mm making the radially outer working layer 26 the axially narrowest working layer.

[0122] Note that SW=205 and T2=166 satisfy the following relationships T2 ≥ SW - 75, preferably T2 ≥ SW - 70 and T2 ≤ SW - 27, preferably T2 ≤ SW - 30.

[0123] As illustrated in the figure 1 , the tire 11 has radially rectified sidewalls. Indeed, 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 and here T2 / A=0.93.

[0124] Each working layer 24, 26 comprises working wire reinforcement elements extending axially from one axial edge 241, 261 to the other axial edge 242, 262 of each working layer 24, 26 substantially parallel to each other in main directions forming with the circumferential direction X of the tire 10, angles AT1 and AT2 respectively of opposite orientations and in absolute value, strictly greater than 10°, preferably ranging from 15° to 50° and more preferably ranging from 20° to 35°. Here, AT1=-26° and AT2=+26°.

[0125] The single carcass layer 36 is delimited axially by two axial edges respectively 361, 362 and comprises textile carcass wire reinforcement elements respectively 360 extending axially from one axial edge 361 to the other axial edge 362 in a main direction D3 forming with the circumferential direction X of the tire 10, an angle AC, in absolute value, ranging from 80° to 90° and here AC=+90°.

[0126] The single carcass layer 36 forms a wrap around each circumferential reinforcing element 33 of each bead 32 such that an axially inner portion 3611, 3621 of the first carcass layer 36 is arranged axially inside an axially outer portion 3612, 3622 of the first carcass layer 36 and such that each axial end 361, 362 of the first carcass layer 36 is arranged radially outside each circumferential reinforcing element 33.

[0127] Each axial end 361, 362 of the single carcass layer 36 is arranged radially inside the equator E of the tire. More precisely, each axial end 361, 362 of the first carcass layer 36 is arranged at a radial distance RNC less than or equal to 30 mm from a radially outer end 331 of each circumferential reinforcing element 33 of each bead 32. Here RNC=23 mm.

[0128] Each working layer 24, 26, hooping layer 28 and carcass layer 36 comprises a calendering matrix for the wire reinforcement elements of the corresponding layer. Preferably, the calendering matrix is ​​polymeric and more preferably elastomeric like those usually used in the field of tires.

[0129] Each hoop wire reinforcement element typically comprises two multifilament strands, each multifilament strand being made up of a yarn of aliphatic polyamide monofilaments, here nylon with a count equal to 140 tex, these two multifilament strands being individually helical at 250 turns per meter in one direction and then helical together at 250 turns per meter in the opposite direction. These two multifilament strands are wound helically around each other.Alternatively, a hooping wire reinforcement element may be used comprising a multifilament strand consisting of a yarn of aliphatic polyamide monofilaments, here nylon with a count equal to 140 tex and a multifilament strand consisting of a yarn of aromatic polyamide monofilaments, here aramid with a count equal to 167 tex, these two multifilament strands being individually helical at 290 turns per meter in one direction and then helical together at 290 turns per meter in the opposite direction. These two multifilament strands are wound helical around each other.In yet another variant, a hoop wire reinforcement element may be used comprising two multifilament strands each consisting of a yarn of aromatic polyamide monofilaments, here aramid with a count equal to 330 tex and a multifilament strand consisting of a yarn of aliphatic polyamide monofilaments, here nylon with a count equal to 188 tex, each of the multifilament strands being individually helically wound at 270 turns per meter in one direction and then helically wound together at 270 turns per meter in the opposite direction. These three multifilament strands are wound helically around each other.

[0130] Generally speaking, the use of a high load leads to a reduction in the acceptable limit speed of the tire as well as a degradation of its behavior, for example its drift rigidity. Thus, by using one or more high modulus hoop wire reinforcement elements, for example like those described in the last two variants above comprising one or more strands of aromatic polyamide, it is possible to increase the acceptable limit speed of the tire and improve the behavior, in particular its drift rigidity.

[0131] Each working wire reinforcement element is an assembly 4.26 of four steel monofilaments and comprising an inner layer of two monofilaments and an outer layer of two monofilaments wound together in a helix around the inner layer at a pitch of 14.0 mm, for example in the S direction. Such an assembly 4.26 has a breaking force equal to 640 N, 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. Alternatively, 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 wound together in a helix at a pitch of 12.5 mm in a first direction, for example the Z direction, and an outer layer of four monofilaments wound together in a helix around the inner layer at a pitch of 12.5 mm in a second direction opposite to the first direction, for example the S direction.

[0132] As shown in the figure 3, each textile carcass wire reinforcement element 360 comprises an assembly of at least two multifilament strands 363, 364. Each multifilament strand 363, 364 is chosen from a polyester multifilament strand, an aromatic polyamide multifilament strand and an aliphatic polyamide multifilament strand, preferably chosen from a polyester multifilament strand and an aromatic polyamide multifilament strand. In this case, the assembly is chosen from an assembly of two polyester multifilament strands and an assembly of a polyester multifilament strand and an aromatic polyamide multifilament strand and here is made up of two PET multifilament strands, these two multifilament strands being individually helical at 270 turns per meter in one direction and then helical together at 270 turns per meter in the opposite direction.Each of these multifilament strands has a count equal to 334 tex so that the total count of the assembly is greater than or equal to 475 tex and here equal to 668 tex. Each textile carcass wire reinforcement element 360 has an average diameter D, expressed in mm such that D ≥ 0.85 mm, preferably D ≥ 0.90 mm and such that D ≤ 1.10 mm, preferably D ≤ 1.00 mm. In this case, D=0.95 mm. PNEUMATIC ACCORDING TO A SECOND EMBODIMENT

[0133] We will now describe a tire according to a second embodiment with reference to: Figures 4 and 5 . Elements similar to those of the first embodiment are designated by identical references.

[0134] Unlike the first embodiment, the tire 11 has the dimension 255 / 40R20, i.e. a nominal section width SW=255, a nominal aspect ratio AR=40 and a nominal rim diameter here equal to 20. The tire 11 of the second embodiment has a sidewall height H defined by SW x AR / 100 =102 ≥ 95, preferably H ≥ 100.

[0135] The marking also includes a load index LI ranging from 98 to 116, such that LI ≥ LI'+1 with LI' being the load index of an EXTRA LOAD tire of the same size according to the ETRTO 2019 standard manual. Preferably, LI'+1 ≤ LI ≤ LI'+4, and even LI'+2 ≤ LI ≤ LI'+4.

[0136] A tire with a dimension 255 / 40R20 in its EXTRA LOAD version has a load index equal to 101 as indicated on page 34 of the Passenger Car Tyres - Tyres with Metric Designation section of the ETRTO 2019 standard manual. Thus, the load index LI of tire 11 is such that LI ≥102, preferably 102 ≤ LI ≤ 105 and even 103 ≤ LI ≤ 105 and here LI=104. This load index equal to 104 corresponds to the load index of a HIGH LOAD CAPACITY tire of dimension 255 / 40R20 as indicated in the ETRTO 2021 manual. Thus, tire 11 is indeed of the HIGH LOAD CAPACITY type.

[0137] The tire 11 is therefore such that 0.82 ≤ H / LI ≤ 0.98 and preferably 0.88 ≤ H / LI ≤ 0.98 and here H / LI=0.98.

[0138] For such a dimension, the ETRTO 2019 standard manual indicates, on page 34 of the Passenger Car Tyres - Tyres with Metric Designation section, a measuring rim with a rim width code equal to 9. Thus, a 200 rim will be used with a rim width code equal to the width code of the measuring rim for the tyre dimension reduced by 0.5, here 8.5, i.e. with a rim width A=215.90 mm.

[0139] Each radially inner 24 and radially outer 26 working layer has an axial width T1=224 mm and T2=210.00 mm respectively.

[0140] It will be noted that, just as in the first embodiment, SW=255 and T2=210 mm satisfy the following relationships T2 ≥ SW - 75, preferably T2 ≥ SW - 70 and T2 ≤ SW - 27, preferably T2 ≤ SW - 30 and that 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 and here T2 / A=0.97.

[0141] Unlike the first embodiment, the tire 11 of the second embodiment comprises first and second carcass layers 36, 37 delimited axially by two axial edges respectively 361, 362, 371, 372 and comprising textile wire carcass reinforcement elements respectively 360, 370 extending axially from one axial edge 361, 371 to the other axial edge 362, 372 in a main direction D3 forming with the circumferential direction X of the tire 10, an angle AC, in absolute value, ranging from 80° to 90° and here AC=+90°.

[0142] Each first and second carcass layer 36, 37 extends in each sidewall 30 and in the crown 12 radially inward of the crown reinforcement 16.

[0143] The first carcass layer 36 forms a wrap around each circumferential reinforcing element 33 of each bead 32 such that an axially inner portion 3611, 3621 of the first carcass layer 36 is arranged axially inside an axially outer portion 3612, 3622 of the first carcass layer 36 and such that each axial end 361, 362 of the first carcass layer 36 is arranged radially outside each circumferential reinforcing element 33. Each axial end 371, 372 of the second carcass layer 37 is arranged radially inside each axial end of the first layer 361, 362 and is arranged axially between the axially inner and outer portions 3611, 3612 and 3621, 3622 of the first layer of carcass 36.

[0144] Each axial end 361, 362 of the first carcass layer 36 is arranged radially inside the equator E of the tire. More precisely, each axial end 361, 362 of the first carcass layer 36 is arranged at a radial distance RNC less than or equal to 30 mm from a radially outer end 331 of each circumferential reinforcing element 33 of each bead 32. Here RNC=23 mm.

[0145] Each textile carcass textile wire reinforcement element 360, 370 of each first and second carcass layer 36, 37 comprises an assembly of at least two multifilament strands 363, 364, 373, 374. Here, each assembly is made up of two multifilament strands of PET, these two multifilament strands being individually helical at 420 turns per meter in one direction and then helical together at 420 per meter in the opposite direction. Each of these multifilament strands has a count equal to 144 tex so that the total count of the assembly is less than or equal to 475 tex and here equal to 288 tex.

[0146] Each textile wire reinforcement element of the carcass 360, 370 has an average diameter respectively D1, D2, expressed in mm 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 and such that D1 ≥ 0.55 mm and D2 ≥ 0.55 mm, preferably D1 ≥ 0.60 mm and D2 ≥ 0.60 mm. Here, D1 = D2 = 0.62 mm. COMPARATIVE TESTS Static test

[0147] It has been illustrated on the figure 6 the result of a static crush test of a tire of size 205 / 40R17 similar to the first embodiment but in which the T2 / A ratio is equal to 1.01 (tire illustrated on the left in which working layers with T1=180 mm and T2=180 mm were used) and the tire according to the first embodiment whose T2 / A ratio is equal to 0.93 (tire illustrated on the right). The load applied to each tire is equal to 560 kg at a pressure of 250 kPa.

[0148] Note that the deflection of the left tire is much greater than the deflection of the right tire. In fact, the distance DR1 from the axis of rotation R to the ground of the left tire is less than the distance DR2 from the axis of rotation R to the ground of the right tire.

[0149] In particular, we note that the sidewalls of the right-hand tire are radially straighter than the sidewalls of the left-hand tire. This can be seen by comparing, at the same radial dimension of each sidewall, the distances DF1 and DF2 between the outer surface of the sidewall located opposite the contact patch and the plane SA perpendicular to the axis of rotation R of the tire and passing through the support face of the rim delimiting the axial width A of the rim. This can also be seen by comparing, at the same radial dimension of each sidewall located at the right of the contact patch, the distances DF1' and DF2' between the outer surface of the sidewall and the plane perpendicular SA. We observe that DF1>DF2 and that DF1'>DF2'. Driving test simulations

[0150] The inventors simulated the rolling of the tires according to the first and second embodiments of the invention mounted on different rims, including the rim having a rim width code equal to the width code of the measuring rim for the tire dimension reduced by 0.5, here 7 for the tire according to the first embodiment and 8.5 for the tire according to the second embodiment. The rolling of the tires according to the first and second embodiments of the invention was also simulated on rims not recommended by the ETRTO 2019 standard manual for the purpose of demonstrating and understanding the technical effect of the invention (rims having a rim width code equal to 6.5 and 8 respectively).

[0151] For each assembled unit, a simulation of a rolling test was carried out similar to the load / speed performance test described in Annex VII of UNECE Regulation No. 30, but under even more demanding conditions.

[0152] During these simulations, the maximum volume energy dissipation DNRJ of the calendering matrix of a portion of the single carcass layer for the tire according to the first embodiment and of a portion of the second carcass layer for the tire according to the second embodiment, located in the sidewall, expressed in daN / mm2, was recorded. The higher this value, the higher the energy dissipation by the tire structure and the greater the temperature rise.

[0153] These values ​​were related to a relative value 100 below which energy dissipation is controlled for the tested dimension and above which energy dissipation is not sufficiently controlled. This relative value 100 is different for each tested dimension.

[0154] The gain in the vehicle's external gauge compared to the measuring rim was also calculated. A negative gain corresponds to an increase in the vehicle's external gauge. For a given rim, a gain in the vehicle's external gauge is necessarily accompanied by a reduction in the rim's mass and therefore a reduction in the rotating masses on the vehicle.

[0155] These values ​​have been collected in Tables 1 and 2 below respectively for each first and second embodiment. Table 1 A (Inches) Gain (cm) T2 / A DNRJ (Base 100) 6,5 5,08 1,01 117 7 2,54 0,93 60 7,5 0 0,87 37 8 -2,54 0,82 43 Table 2 A (Inches) Gain (cm) T2 / A DNRJ (Base 100) 8 5,08 1,03 120 8,5 2,54 0,97 73 9 0 0,92 47 9,5 -2,54 0,87 53

[0156] These tests show that reducing the T2 / A ratio makes it possible to control energy dissipation in the portion of the carcass reinforcement located in the sidewall, even under a relatively high load and with a pressure lower than the pressure recommended to carry the corresponding load.

[0157] Thus, in order on the one hand to control this energy dissipation and, on the other hand, to limit the increase in rotating masses on the vehicle but also the size of the assembled assembly to promote the habitability and compactness of the vehicle, the best compromise is obtained by limiting the axial width T2 and using a rim with a rim width code equal to the width code of the measuring rim for the tire size and defined according to the ETRTO 2019 standard manual reduced by 0.5 so that the T2 / A ratio is less than or equal to 1.00.

[0158] The invention is not limited to the embodiments previously described.

Claims

1. A tyre (11) for a passenger vehicle comprising a crown (12), two beads (32), two sidewalls (30) each connecting each bead (32) to the crown (12), and a carcass reinforcement (34) anchored in each bead (32), the crown (12) comprising a crown reinforcement (16) and a tread (14), the carcass reinforcement (34) extending in each sidewall (30) and in the crown (12) radially internally to the crown reinforcement (16), the crown reinforcement (16) being arranged radially between the tread (14) and the carcass reinforcement (34) and comprising a working reinforcement (20) comprising at least an axially narrowest working layer (26), the axially narrowest working layer (26) having an axial width T2 expressed in mm, the tyre (11) is adapted to be mounted on a mounting support (100) comprising a rim (200), characterized in that the tyre (11) has a load index LI such that LI ≥ LI'+1, LI' being the load index of an EXTRA LOAD tyre of the same size according to the ETRTO 2019 Standards Manual, and in that, when the tyre is mounted on a rim having a rim width code equal to the measuring rim width code for the tyre size defined according to the ETRTO 2019 Standards Manual minus 0.5, the ratio T2 / A is such that T2 / A ≤ 1.00 with A being the rim width A according to the ETRTO 2019 Standards Manual, expressed in mm of the rim.

2. The tyre (11) as claimed in the preceding claim, wherein LI'+1 ≤ LI ≤ LI'+4, preferably LI'+2 ≤ LI ≤ LI'+4.

3. The tyre (11) as claimed in any one of the preceding claims, wherein 0.85 ≤ T2 / A, preferably 0.90 ≤ T2 / A, and more preferentially 0.93 ≤ T2 / A ≤ 0.97.

4. The tyre (11) as claimed in any one of the preceding claims, wherein the tyre (11) has a nominal section width SW such that T2 ≥ SW - 75, preferably T2 ≥ SW - 70.

5. The tyre (11) as claimed in any one of the preceding claims, wherein the tyre (11) has a nominal section width SW such that T2 ≤ SW - 27, preferably T2 ≤ SW - 30.

6. The tyre (11) as claimed in any one of the preceding claims, wherein the tyre (11) has a nominal section width SW ranging from 205 to 315, a nominal aspect ratio ranging from 25 to 55, a nominal rim diameter ranging from 17 to 23 and a load index LI ranging from 98 to 116, preferably a nominal section width SW ranging from 225 to 315, a nominal aspect ratio ranging from 25 to 55, a nominal rim diameter ranging from 18 to 23 and a load index LI ranging from 98 to 116, and more preferentially a nominal section width SW ranging from 245 to 315, a nominal aspect ratio ranging from 30 to 45, a nominal rim diameter ranging from 18 to 23 and a load index LI ranging from 98 to 116.

7. The tyre (11) as claimed in any one of the preceding claims, wherein the tyre (11) has a size and a load index LI chosen from among the following sizes and load indexes: 225 / 55R18 105, 225 / 55ZR18 105, 205 / 55R19 100, 205 / 55ZR19 100, 235 / 45R21 104, 235 / 45ZR21 104, 285 / 45R22 116, 285 / 45ZR22 116, 205 / 40R17 88, 205 / 40ZR17 88, 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, 255 / 35R18 98, 255 / 35ZR18 98, 245 / 35R20 98, 245 / 35ZR20 98, 265 / 35R20 102, 265 / 35ZR20 102, 245 / 35R21 99, 245 / 35ZR21 99, 255 / 35R21 101, 255 / 35ZR21 101, 265 / 35R21 103, 265 / 35ZR21 103, 275 / 35R21 105, 275 / 35ZR21 105, 285 / 35R21 108, 285 / 35ZR21 108, 295 / 35R22 111, 295 / 35ZR22 111, 275 / 35R23 108, 275 / 35ZR23 108, 285 / 30R21 103, 285 / 30ZR21 103, 315 / 30R21 109, 315 / 30ZR21 109, 325 / 30R21 111, 325 / 30ZR21 111, 315 / 30R23 111, 315 / 30ZR23 111.

8. The tyre (11) as claimed in any one of the preceding claims, wherein the working reinforcement (20) comprises a radially inner working layer (24) and a radially outer working layer (26) arranged radially on the outside of the radially inner working layer (24).

9. The tyre (11) as claimed in any one of the preceding claims, wherein the axially narrowest working layer (26) or each working layer (24, 26) is delimited axially by two axial edges (241, 242, 261, 262) of said working layer (24, 26) and comprises working filamentary reinforcing elements extending axially from one axial edge to the other axial edge of said working layer (24, 26) substantially parallel to one another.

10. The tyre (11) as claimed in the preceding claim, each working filamentary reinforcing element extends in a main direction forming an angle which, in terms of absolute value, is strictly greater than 10°, preferably ranging from 15° to 50° and more preferentially ranging from 20° to 35°, with the circumferential direction (X) of the tyre (11).

11. The tyre (11) as claimed in any one of the preceding claims, wherein the carcass reinforcement (34) comprises at least one carcass layer (36, 37), the or each carcass layer (36, 37) being delimited axially by two axial edges (361, 362, 371, 372) of the or each carcass layer (36, 37) and comprises textile carcass filamentary reinforcing elements (360, 370) extending axially from one axial edge to the other axial edge of the or each carcass layer (36, 37) in a main direction forming an angle which, in terms of absolute value, ranges from 80° to 90°, with the circumferential direction (X) of the tyre (11).

12. Use of a tyre (11) for passenger vehicle comprising a crown (12), two beads (32), two sidewalls (30) each connecting each bead (32) to the crown (12), and a carcass reinforcement (34) anchored in each bead (32), the crown (12) comprising a crown reinforcement (16) and a tread (14), the carcass reinforcement (34) extending in each sidewall (30) and in the crown (12) radially internally to the crown reinforcement (16), the crown reinforcement (16) being arranged radially between the tread (14) and the carcass reinforcement (34) and comprising a working reinforcement (20) comprising at least an axially narrowest working layer (26), the axially narrowest working layer (26) having an axial width T2 expressed in mm, on a mounting support (100) comprising a rim (200) so that, when the tyre is mounted on a rim having a rim width code equal to the measuring rim width code for the tyre size defined according to the ETRTO 2019 Standards Manual minus 0.5, the ratio T2 / A is such that T2 / A ≤ 1.00 with A being the rim width A according to the ETRTO 2019 Standards Manual, expressed in mm of the rim, so that the tyre (11) has a load index LI such that LI ≥ LI'+1, LI' being the load index of an EXTRA LOAD tyre of the same size according to the ETRTO 2019 Standards Manual.

13. Use of a tyre (11) according to the preceding claim, so that the tyre (11) is mounted on a vehicle having an hybrid or electric motor.

14. Use of a tyre (11) according to claim 12 or 13, so that the tyre (11) is inflated at a pressure ranging from 200 to 270 kPa.

15. Passenger vehicle comprising at least one tyre (11) as claimed in any one of the claims 1 to 11, passenger vehicle having an hybrid or electric motor.