Tyre with asymmetrical profile and symmetrical carcass passage

Abstract

The invention relates to a tyre (10) which comprises first and second beads (321, 322) comprising circumferential reinforcing elements (331, 332) for anchoring the carcass layer (36) arranged substantially symmetrically with respect to the median plane (M) of the rim. The tyre has axial distances C11, C21 at the equator (E), between the median plane (M) of the rim and the carcass layer (36) passing through the first and second sidewalls (301, 302). The tyre has axial distances F1, F2, at the equator (E), between the median plane (M) of the rim and the theoretical outer surface (44) of the first and second sidewalls (301, 302). 2 x F1 > LN, with LN being the nominal axial width of the tyre according to the manual of the ETRTO 2021 standard. |C11-C21| ≤ 3.0 mm and F1-C11 > F2-C21. G1 ≤ 6.0 mm and / or G2 ≤ 6.0 mm.

Description

Tire with asymmetrical profile and symmetrical carcass passage

[0001] The present invention relates to a tire for a passenger vehicle. By tire is meant a bandage intended to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized or not 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 state of the art is known for conventional passenger vehicle tires having an outer side and an inner side imposed when the tire is mounted on the vehicle. These tires usually comprise a crown, first and second beads, first and second sidewalls connecting each first and second bead respectively to the crown. These tires do not have a rim protector. A rim protector is a projecting circumferential rib located in the radially lower part of the tire sidewall and intended to protect the rim edge from any damage.

[0003] These tires are mounted on their supporting element, for example a rim, to form mounted assemblies. These mounted assemblies are handled many times before being mounted on the passenger vehicle for which they are intended.

[0004] A first problem is that, during these manipulations, the assembled assemblies, in particular the rims, are exposed to shocks often resulting in dents or scratches, making it impossible to sell the vehicle in its current state and requiring the assembly to be taken back and replaced.

[0005] A second problem relates to the aesthetics of the vehicle. Indeed, it is desirable that the exterior surface of the mounted assembly, particularly the exterior surface of the tire, is in line with the bodywork. In particular, a mounted assembly that is arranged significantly back from the exterior bodywork line delimiting the wheel arch is often considered unsightly.

[0006] Another problem is the autonomy of vehicles, and more advantageously of electric vehicles, which car manufacturers are seeking to increase without resorting to additional batteries.

[0007] The aim of the invention is to create a high-performance tire that provides better protection for the tire mounting rim and improves the overall aesthetics of the vehicle without penalizing or even improving the vehicle's autonomy.

[0008] To this end, the invention relates to a tire for a passenger vehicle, the tire having an outer side and an inner side imposed when the tire is mounted on the vehicle, the tire comprising a crown comprising a crown reinforcement, first and second beads, first and second sidewalls respectively connecting each first and second bead to the crown, a carcass reinforcement comprising at least one carcass layer, the or each carcass layer i being anchored in each first and second bead and extending radially in each first and second sidewall and axially in the crown radially inward to the crown reinforcement, the tire comprising a rim median plane constituted by the median plane of the measuring rim of the tire according to the ETRTO 2021 standard manual when the tire is mounted on the measuring rim, the first sidewall and the first bead being arranged on the same side of the rim median plane as the outer side of the tire,the second sidewall and the second bead being arranged on the same side of the rim median plane as the inner side of the tire, each first and second bead respectively comprising at least first and second circumferential reinforcing elements for anchoring the carcass layer or at least one of the carcass layers i, the first and second circumferential reinforcing elements being arranged substantially symmetrically with respect to the rim median plane, the tire having an axial distance C1i, at the equator, between the rim median plane and a first axially outermost point of each carcass layer i passing through the first sidewall, the tire having an axial distance C2i, at the equator, between the rim median plane and a second axially outermost point of the carcass layer i passing through the second sidewall, the tire having an axial distance F1, at the equator,between the rim median plane and a first point of a theoretical external surface of the first sidewall, the tire having an axial distance F2, at the equator, between the rim median plane and a second point of the theoretical external surface of the second sidewall, the tire having an axial thickness G1, at the equator, between a point of a theoretical internal surface of an internal cavity of the tire and a first axially innermost point of the axially innermost carcass layer at the equator passing through the first sidewall, the tire having an axial thickness G2, at the equator, between a point of a theoretical internal surface of the internal cavity of the tire and a second axially innermost point of the axially innermost carcass layer at the equator passing through the second sidewall, pneumatic in which 2 x F1 > LN with LN being the nominal axial width of the pneumatic according to the ETRTO 2021 standard manual, |C1i-C2i| < 3.0 mm and F1-C1 i > F2-C2i and G1 < 6.0 mm and / or G2 < 6.0 mm.

[0009] The invention can be more simply summarized as defining an asymmetrical tire with a symmetrical carcass reinforcement. Indeed, the fact that the first and second annular reinforcing elements are arranged substantially symmetrically with respect to the rim median plane and the fact that |C1i-C2i|<3 mm make the or each carcass layer i anchored in each first and second bead substantially symmetrical with respect to the rim median plane.

[0010] This symmetry of the or each carcass layer i makes it possible to ensure the performance usually expected of a tire, unlike a tire in which there would be at least one carcass layer arranged in a non-symmetrical manner relative to the median plane of the rim and which would induce conicity effects leading to an imbalance of the tire.

[0011] The fact that F1-C1 i > F2-C2i allows us to characterize an asymmetry of the sidewall thicknesses. This asymmetry associated with the fact that 2 x F1 > LN with LN being the nominal axial width LN of the tire according to the manual of the standard of the European Tire and Rim Technical Organization or "ETRTO", 2021 allows on the one hand to effectively protect the mounting rim. Indeed, the protection provided by the tire is improved by thickening the first sidewall arranged on the outside and by making the actual axial width of the tire exceed the nominal axial width LN.

[0012] This asymmetry, combined with the fact that 2 x F1 > LN, also makes it possible to make the outer surface of the tire flush with the outer body line delimiting the wheel arch. The asymmetry and the value of F1 will be adapted by the person skilled in the art according to the outer body line of the vehicle on which the tire is intended to be mounted.

[0013] The thickening of the first flank arranged on the outside is compensated by a thinning of the second flank arranged on the inside. On the one hand, this thinning does not hinder the protection of the mounted assemblies because any impacts suffered on the inside cause dents or scratches that are not visible and are therefore acceptable from the point of view of selling the vehicle. On the other hand, this thinning does not hinder the aesthetics of the vehicle given the invisibility of the second flank arranged on the inside and hidden when the mounted assembly is mounted on the vehicle. Finally, the thinning makes it possible to at least partially compensate for the mass added to thicken the first flank on the outside, which makes it possible to contain the quantity of material used.

[0014] The tire according to the invention also has improved aerodynamic performance compared to the tire of the prior art, which is all the more surprising since one might have expected a decrease in aerodynamic performance due to the thickening of the first sidewall arranged on the outer side. On the contrary, the invention teaches that the presence of a relatively thin second sidewall arranged on the inner side makes it possible to derive an aerodynamic benefit greater than the aerodynamic degradation associated with the presence of a relatively thick first sidewall arranged on the outer side. Thus, the autonomy of the vehicle equipped with the tire according to the invention is improved.

[0015] One and / or the other of the axial thicknesses G1, G2 being relatively low makes it possible to characterize a tire that cannot provide a run-flat function. A tire having one and / or the other of the axial thicknesses G1, G2 being relatively low has reduced hysteresis and therefore relatively low rolling resistance and, all other things being equal, in any case lower than a tire suitable for similar run-flat operation having much larger axial thicknesses G1, G2. Preferably, G1 < 6.0 mm and G2 < 6.0 mm.

[0016] The tire according to the invention is not a tire suitable for running flat. A tire suitable for running flat is suitable for running in which the pressure in the internal cavity of the tire is equal to atmospheric pressure (by misuse of language, it is often said that the pressure is zero when it is the excess pressure relative to atmospheric pressure that is zero).A tire suitable for run-flat operation comprises self-supporting sidewalls, i.e., sidewalls capable of carrying, in the presence of a pressure equal to atmospheric pressure, the same load, for example the nominal load as indicated in the European Tyre and Rim Technical Organisation or “ETRTO” standard manual, 2021, as the tire is capable of carrying when inflated to its usual inflation pressure, for example its nominal inflation pressure as indicated in the ETRTO standard manual, 2021, and this for a mileage greater than or equal to a certain threshold at a speed greater than or equal to 80 km / h. A tire suitable for run-flat operation preferably has a specific marking indicating the tire's ability to run flat.For example, the following acronym markings are used, but this list is not exhaustive: "ZP" for "Zero Pressure", "SST" for "Self Supporting Technology", "SSR" for "Self Supporting Runflat Tire", "RF" for "Run Flat", "RFT" for "Run Flat Tire", "EXT" for "EXTended", "ZP-SR" for "Zero Pressure Short Range" or "ZPS" for "Zero Pressure System". Another specific marking indicating the capacity of the. A run-flat tire is the presence of the letter "F" in the tire dimension. Thus, tires with dimensions 225 / 40R18 or 225 / 40ZR18, if they are suitable for running flat, have the markings 225 / 40RF18 or 225 / 40ZRF18.

[0017] The tire has an internal surface delimiting the inflation cavity of the tire once the latter is mounted on a mounting support, for example a rim.

[0018] By arranged substantially symmetrically with respect to the rim median plane, it is understood that the position of the first circumferential reinforcing element is substantially symmetrical with the position of the second circumferential reinforcing element with respect to the rim median plane so as to ensure the symmetry of each carcass layer which is anchored by means of these at least first and second circumferential reinforcing elements. Thus, for example, in the case of first and second circumferential reinforcing elements of identical general annular shape, the geometric centers are equidistant from the rim median plane.

[0019] The theoretical external surface is the surface of the tire free of recessed or protruding molded elements and following the curvature of the external surface of the tire without sudden local variation. This theoretical external surface serves as a reference for determining the depth of the height of the recessed or protruding molded elements. Thus, the theoretical external surface is the assembly formed by the smooth surface passing through the surface of the tire free of recessed or protruding molded elements and by an imaginary surface following the curvature of the external surface of the tire and continuously extending the smooth surface, ignoring the recessed or protruding molded elements.

[0020] Similarly, the theoretical internal surface of the cavity is the internal surface of the tire free of recessed or protruding molded elements and following the curvature of the internal surface of the tire without sudden local variation. This theoretical internal surface serves as a reference for determining the depth of the height of the recessed or protruding molded elements. Thus, the theoretical internal surface is the assembly formed by the smooth surface passing through the surface of the tire free of recessed or protruding molded elements and by an imaginary surface following the curvature of the internal surface of the tire and continuously extending the smooth surface, ignoring the recessed or protruding molded elements.

[0021] The axial distances F1 and F2 are measured on a tire mounted on a measuring rim according to the ETRTO 2021 standard manual and inflated to 2.5 bars after positioning the rim median plane in relation to the tire. The distances C1i, C2i, G1 and G2 are measured under a pressure equal to 2.5 bars, for example, by pressurizing to 2.5 bars a section of the tire mounted on a measuring rim according to the ETRTO 2021 standard manual, for example by means of an inflatable bag inserted between the measuring rim and the section of the tire. It is also possible to take a profile measurement of the rim alone and then take a profile measurement with the tire mounted on the rim. The superposition of the two measured profiles makes it possible to determine the axial distances F1 and F2, then F1-C1i and F2-C2i and finally C1i and C2i. We can also mention the existence of rims equipped with LASER measuring devices capable of directly measuring C1i and C2i.

[0022] Each first and second axially outermost point of each carcass layer i belongs to an axially outer surface of each carcass layer i. For each carcass layer i, a continuous surface, called the axially outer surface of said carcass layer i, passing through the axially outermost point of each carcass reinforcement element, and a continuous surface, called the axially inner surface of said carcass layer i, passing through the axially innermost point of each carcass reinforcement element, are defined.

[0023] The or each carcass layer comprises carcass reinforcing elements extending from a first axial edge to a second axial edge of the or each carcass layer. By reinforcing element is meant an element allowing the mechanical reinforcement of the polymer matrix in which this reinforcing element is intended to be embedded.

[0024] Preferably, the reinforcing element is wire-like, that is to say that the element has 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 or square or oval. In the case of a rectangular section, the wire-like reinforcing element has the shape of a strip.

[0025] The matrix is ​​said to be polymeric because it is based on a polymeric composition, this polymeric composition being able to comprise one or more polymers, for example chosen from thermoplastic polymers, thermosetting polymers, elastomers, thermoplastic elastomers, but also fillers and other components usually used in the field of compositions for tires, in particular compositions for embedding reinforcing elements.

[0026] For a given dimension, the nominal axial width LN is that mentioned in the ETRTO 2021 standard manual under the name “Design - Section Width”. Thus, for example, for a tire of dimension 235 / 55R18, the nominal axial width LN is equal to 245.0 mm.

[0027] By imposed inner and outer sides when the tire is mounted on the vehicle, we mean that the tire is designed so that one of its sides is arranged on the inner side and the other of its sides is arranged on the outer side. This orientation imposed by the tire manufacturer ensures that the tire has the expected performance. Indeed, mounting a tire with an orientation different from that imposed by the manufacturer can lead to unexpected behavior of the vehicle. By outer side, we mean the side of the tire entirely visible from the outside of the vehicle when the tire is mounted on the vehicle. By inner side, we mean the side of the tire facing the wheel arch of the vehicle on which it is mounted. Generally, the tire has a marking indicating the inner side and the outer side.

[0028] 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.

[0029] Axial direction means the direction substantially parallel to the axis of revolution of the tire, i.e. the axis of rotation of the tire.

[0030] Circumferential direction means the direction which is substantially perpendicular to both the axial direction and a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[0031] Radial direction means the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[0032] The rim median plane (denoted M) is the plane perpendicular to the tire's axis of rotation that is located axially equidistant from the two flanges or hooks of the measuring rim according to the ETRTO 2021 standard manual. For most passenger vehicle tires, the measuring rim has a profile type J or B whose flanges or hooks are axially spaced from each other by a distance A (as mentioned in the ETRTO 2021 standard manual). The rim median plane is thus located at an axial distance A / 2 from each of the flanges or hooks of the measuring rim. The measuring rim depends on the tire size and is indicated in the ETRTO 2021 standard manual. Thus, for a size 235 / 55R18, the measuring rim has a code 7.5 and a profile type J.

[0033] By equatorial circumferential plane of the tire, we mean, in a meridian section plane, the plane passing through the equator (noted E) of the tire, perpendicular to the median plane and to the radial direction. The equator of the tire is, in a plane of meridian section (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 passing through first and second points of the internal surface delimiting the internal cavity of the tire, the first and second points of the internal surface being the points of the internal surface axially furthest from each other and belonging respectively to each first and second sidewall.

[0034] Meridian plane means a plane parallel to the axis of rotation of the tire and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0035] 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 rim median plane, respectively further from the rim median plane.

[0036] 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.

[0037] 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).

[0038] The tires are, in preferred embodiments of the invention, intended for passenger vehicles as defined in the ETRTO 2021 standard manual. Such a tire has a section in a meridian cutting plane characterized by a section height H and a nominal section width or flange thickness S in the sense of the ETRTO 2021 standard manual such that the H / S ratio, expressed as a percentage, is at most equal to 90 and is at least equal to 25, and the nominal section width S is at least equal to 115 mm and at most equal to 385 mm. In addition, the hook diameter D, defining the diameter of the tire mounting rim, is at least equal to 12 inches, preferably at least equal to 16 inches and at most equal to 24 inches.

[0039] Conventionally, the crown comprises a tread and a crown reinforcement extending into the crown in the circumferential direction, the crown reinforcement being arranged radially between the tread and the carcass reinforcement.

[0040] Conventionally, the crown reinforcement comprises at least one crown layer comprising reinforcing elements. These reinforcing elements are preferably textile or metal wire elements.

[0041] In embodiments allowing the performance of so-called radial tires to be obtained, for example as defined by the ETRTO, each carcass wire reinforcement element extending substantially in a main direction forming with the circumferential direction of the tire, an angle, in absolute value, preferably ranging from 80° to 90°.

[0042] In preferred embodiments in which the or each carcass layer is made as symmetrical as possible with respect to the median plane of the rim, |C1i-C2i| < 2.0 mm, preferably |C1i-C2i| < 1.0 mm and more preferably |C1i-C2i| < 0.5 mm.

[0043] Very preferably, for each given radial dimension r, each point of the or each carcass layer i located on the outer side has an axial distance from the median plane C1ir, each point of said carcass layer i located on the inner side at the same radial dimension r has an axial distance from the median plane C2ir, we have |C1ir-C2ir| < 3.0 mm, preferably |C1ir-C2ir| < 2.0 mm, more preferably |C1ir-C2ir| < 1.0 mm and very preferably |C1ir-C2ir| < 0.5 mm. The radial dimension can be determined relative to any fixed point of the tire, for example relative to the radially innermost point of the tire.

[0044] In embodiments in which the asymmetry of the thicknesses of the flanks is relatively large, (F1-C1i)-(F2-C2i) > 2.0 mm, preferably (F1-C1i)-(F2-C2i) > 2.5 mm.

[0045] In embodiments in which the asymmetry of the sidewall thicknesses remains contained, (F1-C1i)-(F2-C2i) < 5.0 mm, preferably (F1-C1i)-(F2-C2i) < 3.0 mm. Indeed, too great an asymmetry of the sidewall thicknesses would generate sidewall flexural stiffnesses that are too different so that the carcass reinforcement would not be arranged symmetrically with respect to the median plane of the rim when the tire is inflated.

[0046] In advantageous but optional embodiments in which the axial thickness G1 and / or G2 is further reduced, G1 < 4.0 mm and / or G2 < 4.0 mm, preferably G1 < 3.0 mm and / or G2 < 3.0 mm. Advantageously, G1 < 4.0 mm and G2 < 4.0 mm, preferably G1 < 3.0 mm and G2 < 3.0 mm.

[0047] In advantageous but optional embodiments in which the cavity is made as symmetrical as possible with respect to the median plane of the rim, |G1-G2| < 3.0 mm, preferably |G1-G2| < 2.0 mm, more preferably |G1-G2| < 1.0 mm and even more preferably |G1-G2| < 0.5 mm.

[0048] In advantageous but optional embodiments, the tire has an axial thickness E1, at the equator, between the first point of the theoretical outer surface of the first sidewall and the first axially outermost point of the axially outermost carcass layer at the equator such that E1 > 3.0 mm. In other words, F1-C1e > 3.0 mm where C1e denotes the value of the distance 01 i from the axially outermost carcass layer at the equator.

[0049] In advantageous but optional embodiments, the tire has an axial thickness E1 at the equator, between the first point of the theoretical outer surface of the first sidewall and the first axially outermost point of the axially outermost carcass layer at the equator such that E1 < 6.0 mm. In other words, F1-C1e < 6.0 mm where C1e denotes the value of the distance C1 i from the axially outermost carcass layer at the equator.

[0050] In advantageous but optional embodiments, the tire has an axial thickness E2, at the equator, between the second point of the theoretical outer surface of the second sidewall and the second axially outermost point of the axially outermost carcass layer at the equator such that E2 > 1.0 mm. In other words, F2-C2e > 1.0 mm where 02e denotes the value of the distance C2i of the axially outermost carcass layer at the equator.

[0051] In advantageous but optional embodiments, the tire has an axial thickness E2, at the equator, between the second point of the theoretical outer surface of the second sidewall and the second axially outermost point of the axially outermost carcass layer at the equator such that E2 < 3.0 mm. In other words, F2-C2e < 3.0 mm where C2e denotes the value of the distance C2i of the axially outermost carcass layer at the equator. The lower the axial thickness E2, the greater the gain in aerodynamic performance.

[0052] In the preceding embodiments, in the variants in which the axially outermost carcass layer at the equator has a superposition on itself at the equator, the axially outermost point is therefore the point located on the axially outermost superimposed portion at the equator. In other variants in which the axially outermost carcass layer at the equator does not have a superposition on itself at the equator, the axially outermost point is therefore the axially outermost point of the only portion present at the equator.

[0053] In embodiments requiring a relatively large tire width, 2 x F1 > LN + 0.5 mm, preferably 2 x F1 > LN + 1.0 mm, F1 and LN being expressed in mm.

[0054] In order to comply with ETRTO regulatory constraints, the axial width of the tire at the equator is preferably less than or equal to the maximum axial width of the tire according to the ETRTO 2021 standard manual.

[0055] The axial width of the tire at the equator is measured by pressurizing the tire mounted on a measuring rim to 2.5 bars according to the ETRTO 2021 standard manual.

[0056] In advantageous but optional embodiments, the tire comprises a tread surface having an axial width LS such that LR-LS > 10.0 mm with LR being the reference width of the tire tread surface according to the ETRTO 2021 standard manual, LS being determined at 80% of the tire load capacity of the ETRTO 2021 standard manual and at a pressure of 2.5 bar.

[0057] By having an axial width LS of the tread surface significantly smaller than the reference width LR, the contact surface with the rolling ground is reduced, which makes it possible to reduce the noise generated by the tire. In addition, the wet grip of the tire is improved. In these embodiments, the tire therefore has a particularly optimized profile in which, instead of widening the tread to geometrically accompany the presence of the relatively thick first sidewall on the outer side, the axial width of the tread surface is limited for reasons of noise and wet grip.

[0058] Conventionally, the tread surface is delimited axially by first and second axial edges. The axial width LS is the width measured in the axial direction between the first and second axial edges. The first and second axial edges of the tread surface are determined on a tire mounted on a nominal rim within the meaning of the ETRTO 2021 standard manual and inflated to a pressure of 2.5 bar. The first and second axial edges of the tread surface are arranged on either side of the median plane of the tire and formed by lines substantially parallel to the circumferential direction of the tire. In the case of an obvious boundary between the tread surface and the rest of the tire, the first and second axial edges of the tread surface are determined simply.In the case where the tread surface is continuous with the external surfaces of the tire sidewalls, the first and second axial edges can, for example, be determined by loading the tire to 80% of its load capacity according to the ETRTO 2021 standard manual and identifying the first and second axial edges as the axial limits of the tread in contact with the ground.

[0059] The reference width LR of the tread surface is the reference width of the ETRTO 2021 standard manual described on page PC.7 of the “DESIGN GUIDE - Passenger Car Tyres” part of the said manual and defined by LR=(1.075-0.005 x ar) xs A (1.001) with s the theoretical flange thickness on the measuring rim and ar the nominal aspect ratio.

[0060] In advantageous embodiments for further improving the autonomy of vehicles by improving the aerodynamic performance of the tire, the tire comprising a first portion, called the shoulder, of the first sidewall extending from a first axial edge of the rolling surface to the equator, the first shoulder portion has a theoretical external surface having a minimum radius of curvature greater than or equal to 25.0 mm. The greater the minimum radius of curvature, the better the aerodynamic performance of the tire.

[0061] The radius of curvature on the first shoulder portion can be variable. Thus, the minimum radius of curvature is the smallest value of the radius of curvature values ​​on the first shoulder portion.

[0062] Advantageously, the tire comprising a first portion, called the shoulder portion, of the first sidewall extending from a first axial edge of the rolling surface to the equator, the first shoulder portion has a theoretical external surface having a minimum radius of curvature less than or equal to 200.0 mm.

[0063] Advantageously, the tire comprising a first portion, called the shoulder portion, of the first sidewall extending from a first axial edge of the rolling surface to the equator, the first shoulder portion has a theoretical external surface having, outside the equator, a minimum radius of curvature Rmin, and at the equator a radius of curvature RE such that Rmin > RE / 2. Thus, one benefits from having a relatively thick first sidewall on the outside of the tire to ensure that the radius of curvature varies very little on the first shoulder portion. This improves the aerodynamic flow of air over the tire.

[0064] The bending radii and curvatures are measured by pressurizing the tire mounted on a measuring rim to a pressure of 2.5 bars according to the ETRTO 2021 standard manual. No load is applied to the tire.

[0065] The first axial edge from which the first portion extends is of course the end of the rolling surface located on the outer side of the tire.

[0066] In preferred embodiments, the tire is devoid of a rim protector. By devoid of a rim protector, it is meant that the tire is devoid of a projecting circumferential rib located in the radially lower part of the tire sidewall (i.e. in the half of the sidewall located radially inside the tire equator) and intended to protect the rim edge. Such rim protectors are known to those skilled in the art and are notably mentioned in the ETRTO 2021 standard manual.

[0067] The invention will be better understood on reading the description which follows, given solely by way of non-limiting example and made with reference to the drawings in which: Figure 1 is a view, in a meridian section plane, of a tire according to a first embodiment of the invention, Figures 2 and 3 are detail views illustrating a portion respectively of each first and second sidewall of the tire of Figure 1, and Figures 4, 5 and 6 are views similar to those of Figures 1, 2 and 3 of a tire according to a second embodiment, and Figures 7, 8 and 9 are views similar to those of Figures 1, 2 and 3 of a tire according to a third embodiment.

[0068] The figures show a reference X, Y, Z corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions of a tire.

[0069] Figure 1 shows a tire for a passenger vehicle, in accordance with the invention and designated by the general reference 10. The tire 10 has a substantially toric shape around an axis of revolution substantially parallel to the axial direction Y. The tire 10 is intended for a passenger vehicle and has dimensions 235 / 55 R18. In the various figures, the tire 10 is shown in new condition, that is to say not yet having been driven. The tire 10 comprises an inner side INT and an outer side EXT imposed when the tire 10 is mounted on a vehicle.

[0070] In Figure 1, the tire 10 is mounted on a mounting support, here a rim of measurement J conforming to the ETRTO 2021 standard manual, i.e. a 7.5 J rim. The rim J has a median plane M arranged at axial equidistance from the first and second edges R1, R2.

[0071] The tire 10 comprises a crown 12 comprising a tread 14 carrying a rolling surface 15 intended to come into contact with a ground during rolling. The rolling surface 15 is delimited axially by first and second axial edges 151, 152. The rolling surface 15 has an axial width LS determined at 80% of the load capacity of the tire in the ETRTO 2021 standard manual, i.e. under a load of 640 kg and at a pressure of 2.5 bars. axial width LS is such that LR-LS > 10.0 mm with LR being the reference width of the tire tread surface according to the ETRTO 2021 standard manual. Here LR=197.0 mm LS=185.0 mm.

[0072] The crown 12 comprises a crown reinforcement 16 extending in the crown 12 in the circumferential direction X. The tire 10 also comprises an internal sealing layer 18 to an inflation gas being intended to delimit an internal cavity 17 with a mounting support of the tire 10 once the tire 10 is mounted on the mounting support, for example a rim, this cavity being intended to be pressurized by the inflation gas. The internal sealing layer 18 carries an internal surface 19 of the tire 10 delimiting the internal cavity 17 of the tire 10.

[0073] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22. The working reinforcement 20 comprises at least one working layer and here comprises two working layers comprising a radially inner working layer 24 and a radially outer working layer 26 arranged radially outside the radially inner working layer 24.

[0074] The hoop reinforcement 22 comprises at least one hoop layer and here comprises a hoop layer 28.

[0075] The crown reinforcement 16 is arranged radially inside 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.

[0076] The tire 10 comprises first and second sidewalls 301, 302 extending the crown 12 radially inward. The tire 10 further comprises first and second beads 321, 322 radially inward of each first and second sidewall 301, 302. Each first and second sidewall 301, 302 respectively connects each first and second bead 321, 322 to the crown 12.

[0077] The 10 tire does not have a rim protector.

[0078] The tire 10 can be divided so as to distinguish in particular a first portion 311 called the shoulder portion of the first sidewall 301 extending from the first axial edge 151 of the tread surface 15 to the equator E. It is also possible to distinguish a second portion 312 called the shoulder portion of the second sidewall 302 extending from the second axial edge 152 of the tread surface 15 to the equator E.

[0079] The first bead 321 and the first sidewall 301 are arranged on the same side of the rim median plane M as the outer side EXT. The second bead 322 and the second sidewall 302 are arranged on the same side of the rim median plane M as the outer side interior INT.

[0080] The tire 10 comprises a carcass reinforcement 34. 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, here a single carcass layer 36, anchored in each bead 321, 322. The carcass layer 36 extends radially in each first and second sidewall 301, 302 and axially in the crown 12 radially inside the crown reinforcement 16.

[0081] Each first and second bead 321, 322 respectively comprises first and second circumferential reinforcing elements 331, 332 for anchoring the carcass layer 36. The first and second circumferential reinforcing elements 331, 332 are arranged substantially symmetrically with respect to the rim median plane M.

[0082] The carcass layer 36 anchored in each first and second bead 321, 322 forms a winding around respectively each first and second circumferential reinforcing element 331, 332 of each first and second bead 321, 322 such that an axially inner portion 3611, 3621 of the carcass layer 36 anchored in each bead 32 is arranged axially inside an axially outer portion 3612, 3622 of the carcass layer 36 anchored in each first and second bead 321, 322 and such that each axial end 361, 362 axially delimiting the carcass layer 36 anchored in each first and second bead 321, 322 is arranged radially at the outside of each first and second circumferential reinforcing element 331, 332. Each axial end 361, 362 of the carcass layer 36 anchored in each first and second bead 321, 322 is arranged radially inside the equator E.

[0083] Each working layer 24, 26, hooping layer 28 and carcass layer 36 comprises a polymeric matrix, here elastomeric, in which one or more reinforcing elements of the corresponding layer are embedded, here wire reinforcement elements. The structure of the different layers and of the different reinforcing elements is conventional, as for example described in applications WO2021250331, WO2022074341 or WO2022069819.

[0084] In particular, with reference to Figures 2 and 3, the carcass layer 36 comprises wire reinforcement elements 360 embedded in a polymer matrix 363. The wire reinforcement elements 360 extend axially from one axial end to the other of the carcass layer 36 in a main direction forming with the circumferential direction X of the tire 10, an angle, in absolute value, greater than or equal to 60°, preferably ranging from 80° to 90° and here equal to 90°. The carcass layer 36 comprises an axially outer surface SAE passing through the axially outermost point of each carcass reinforcement element 360 as well as an axially inner surface SAI passing through the axially innermost point of each carcass reinforcement element 360. The carcass layer 36 is separated from the adjacent compositions with which its polymeric matrix 363 is in contact by axially inner interfaces IAI and outer interfaces IAE. In particular, in a general manner and without this being specific to the embodiment described, the axially outermost carcass layer, here the carcass layer 36, is in contact with an outer layer 38 arranged axially to the outside and in contact with the carcass layer 36, the outer layer 38 carrying an outer surface 40 of the tire 10.The axially innermost carcass layer, here the carcass layer 36, is also in contact with the internal sealing layer 18 carrying the internal surface 19.

[0085] Each first and second shoulder portion 311, 312 comprises molded elements 42 in a hollow or protruding shape and has a theoretical external surface 44 ignoring the molded elements 42. The theoretical external surface 44 of the first shoulder portion 311 has a minimum radius of curvature Rmin greater than or equal to 25.0 mm and less than or equal to 200.0 mm and here equal to 44.0 mm.

[0086] The radius of curvature RE of the tire 10 at the equator E and the minimum radius of curvature Rmin of the first shoulder portion 311 outside the equator are such that Rmin > RE / 2. Here, Rmin = 44.0 mm and RE = 51.0 mm.

[0087] At equator E, the thickness E1 between the first point P1 of the theoretical external surface 44 of the first sidewall 301 and the first axially outermost point P3 of the axially outermost carcass layer, here of the carcass layer 36, is such that 3.0 mm < E1 < 6.0 mm. Here, E1 = 4.7 mm.

[0088] At equator E, the thickness E2 between the second point P2 of the theoretical external surface 44 of the second sidewall 302 and the second axially outermost point P4 of the axially outermost carcass layer, here of the carcass layer 36, is such that 1.0 mm < E2 < 3.0 mm. Here, E2 = 1.8 mm.

[0089] For each given radial dimension r, each point of the carcass layer 36 located on the outer side EXT has an axial distance from the median plane C11 r, each point of the carcass layer 36 located on the inner side INT at the same radial dimension r has an axial distance from the median plane C21 r. We have |C1 ir-C2ir| < 3.0 mm, preferably |C1 ir-C2ir| < 2.0 mm, more preferably |C1 ir-C2ir| < 1.0 mm and very preferably |C1 ir-C2ir| < 0.5 mm.

[0090] At the equator E, the tire 10 has an axial thickness G1 between a point K1 of a theoretical internal surface 21, here the internal surface 19, of the internal cavity 17 and a first axially innermost point K3 of the axially innermost carcass layer 36 at the equator E passing through the first sidewall 301. At the equator E, the tire 10 has an axial thickness G2 between a point K2 of the theoretical inner surface 21, here the inner surface 19, of the internal cavity 17 and a second axially innermost point K4 of the axially innermost carcass layer 36 at the equator E passing through the second sidewall 302. Here, G1 < 6.0 mm and G2 < 6.0 mm, preferably G1 < 4.0 mm and G2 < 4.0 mm and more preferably G1 < 3.0 mm and G2 < 3.0 mm. Here also, |G1-G2| < 3.0 mm, preferably |G1-G2| < 2.0 mm, more preferably |G1-G2| < 1.0 mm and even more preferably |G1-G2| < 0.5 mm. In particular, in the illustrated embodiment, G1=G2=1.5 mm.

[0091] At equator E, the tire 10 has an axial distance 011 between the rim median plane M and the first axially outermost point P3 of the carcass layer 36 passing through the first sidewall 301. At equator E, the tire 10 has an axial distance C21 between the rim median plane M and the second axially outermost point P4 of the carcass layer 36 passing through the second sidewall 302. Here, 011=118.3 mm and 021=118.2 mm so that |C11-C21 | < 3.0 mm, preferably |C11-C21 | < 2.0 mm, more preferably |C11-C21 | < 1.0 mm and even more preferably |C11-0211 < 0.5 mm.

[0092] Still at equator E, the tire 10 has an axial distance F1 between the rim median plane M and the first point P1 of the theoretical external surface 44 of the first sidewall 301 and an axial distance F2 between the rim median plane M and the second point P2 of the theoretical external surface 44 of the second sidewall 302. Here, F1 = 122.9 mm and F2 = 120.3 mm so that F1-C11 > F2-C21 and so that 2.0 mm < (F1-C1)-(F2-C2) < 5.0 mm and preferably (F1-C1)-(F2-C2) < 3.0 mm. Here (F1-C1)-(F2- C2)= (122, 9-118, 3)-(120, 3-118,2)= 4.6 - 2.1 = 2.5 mm.

[0093] At equator E, tire 10 has an axial width LA between points P1 and P2 equal to the sum F1+F2 and here equal to 243.2 mm. Tire 10 has a nominal axial width LN according to the ETRTO 2021 standard manual equal to 245 mm. Here, 2 x F1 > LN and even 2 x F1 > LN + 0.5 mm, F1 and LN being expressed in mm, LN being the nominal axial width of the tire according to the ETRTO 2021 standard manual.

[0094] We will now describe with reference to Figures 4 to 9 tires respectively according to second and third embodiments. In these figures, elements similar to those of Figures 1 to 3 are designated by identical references.

[0095] Unlike the tire according to the first embodiment, in the second embodiment illustrated in Figures 4 to 6, each axial end 361, 362 of the carcass layer 36 anchored in each first and second bead 321, 322 and forming a winding is arranged radially outside the equator E and even more preferably arranged axially inside the axial ends of the working 24 and hooping 28 layers of the crown reinforcement 16. As illustrated in Figure 5, the first axially outermost point P3 of the carcass layer 36 passing through the first sidewall 301 is the axially outermost point of the axially outermost portion of the carcass layer 36 passing through the first sidewall 301.As illustrated in Figure 6, the second axially outermost point P4 of the carcass layer 36 passing through the second sidewall 302 is the axially outermost point of the axially outermost portion of the carcass layer 36 passing through the second sidewall 302.

[0096] Unlike the tire according to the first and second embodiments, the carcass reinforcement 34 of the tire 10 according to the third embodiment of FIGS. 7 to 9 comprises first and second carcass layers 36, 37 anchored in each first and second bead 321, 322. Each axial end 371, 372 of the second carcass layer 37 is arranged axially outside each axially outer portion 3612, 3622 of the first carcass layer 36. In this third embodiment, only the first carcass layer 36 is anchored in each first and second bead 321, 322 by means of the first and second circumferential anchoring reinforcement elements 331, 332.

[0097] Each first and second carcass layer 36, 37 respectively comprises an axially outer surface SAE36, SAE37 passing through the axially outermost point of each carcass reinforcing element 360, 370 as well as an axially inner surface SAI36, SAI37 passing through the axially innermost point of each carcass reinforcing element 360, 370. Each first and second carcass layer 36, 37 is separated from adjacent compositions with which its polymeric matrix 363, 373 is respectively in contact by axially inner interfaces IAI36, IAI37 and outer interfaces IAE36, IAE37 respectively.

[0098] At equator E, each first and second axially outermost point of the axially outermost carcass layer is each axially outermost point P3, P4 of the second carcass layer 37.

[0099] At the equator E, in addition to the axial distance C11 between the rim median plane M and the first axially outermost point P3 of the second carcass layer 37 passing through the first sidewall 301, the tire 10 has a distance C12 between the rim median plane M and the first axially outermost point P3' of the first carcass layer 36 passing into the first sidewall 301.

[0100] At equator E, in addition to the axial distance C21 between the rim median plane M and the second axially outermost point P4 of the second carcass layer 37 passing through the second sidewall 302, the tire 10 has a distance C22 between the rim median plane M and the first axially outermost point P4' of the first carcass layer 36 passing through the second sidewall 302. In the third embodiment, C11 = 118.3 mm, C12 = 117.1 mm, C21 = 118.2 mm and C22 = 117.0 mm so that |C11 -C211 < 0.5 mm and |C12-C22| < 0.5 mm.

[0101] In the third embodiment, F1=122.9 mm and F2=120.3 mm so that F1-C11 > F2-C21, F1-C12 > F2-C22 and so that 2.0 mm < (F1-C11)-(F2-C21) < 5.0 mm and preferably (F1-C11)-(F2-C21) < 3.0 mm and 2.0 mm < (F1-C12)-(F2-C22) < 5.0 mm and preferably (F1-C12)-(F2-C22) < 3.0 mm. Here (F1-C11)-(F2-C21)= (F1-C12)-(F2-C22)=2.5 mm.

[0102] COMPARATIVE TESTS

[0103] Tires conforming to the invention and as described above were tested, as well as control tires having sidewalls that were perfectly symmetrical with respect to the median plane of the rim.

[0104] The four control tires were mounted on a vehicle and placed in a wind tunnel under normal test conditions. Then, the same vehicle equipped with four tires in accordance with the invention was placed under the same test conditions. In both cases, the product S x Cx was determined, in which S is the frontal area of ​​the vehicle and Cx is the air penetration coefficient of the vehicle. A significant decrease in the product S x Cx was measured when the control tires were replaced by the tires in accordance with the invention, which demonstrates the aerodynamic benefit of the invention.

[0105] The invention is not limited to the embodiments previously described.

[0106] The invention may be used in the case of a tire comprising several first and several second circumferential anchoring reinforcement elements, a portion of the carcass layer being arranged axially between two of the at least first circumferential reinforcement elements in the first bead and between two of the at least second circumferential reinforcement elements in the second bead, for example as described in WO2021 / 123522.

[0107] In order to maximize the aerodynamic gain, the invention will preferably be used with a mounting support having an outer face that is as closed as possible.

[0108] Always in order to maximize the aerodynamic gain, the molded elements will be preferably molded in hollow. If molded elements are molded in prominence, the maximum height of each of these molded elements in relation to the theoretical external surface is less than or equal to 0.2 mm.

Claims

CLAIMS 1. A tire (10) for a passenger vehicle, the tire (10) having an outer side (EXT) and an inner side (INT) imposed when the tire is mounted on the vehicle, the tire comprising a crown (12) comprising a crown reinforcement (16), first and second beads (321, 322), first and second sidewalls (301, 302) respectively connecting each first and second bead (321, 322) to the crown (12), a carcass reinforcement (34) comprising at least one carcass layer (36), the or each carcass layer i (36) being anchored in each first and second bead (321, 322) and extending radially in each first and second sidewall (301, 302) and axially in the crown (12) radially internal to the crown reinforcement (16),the tire (10) comprising a median plane (M) of the rim (J) constituted by the median plane of the measuring rim of the tire according to the ETRTO 2021 standard manual when the tire is mounted on the measuring rim, the first sidewall (301) and the first bead (321) being arranged on the same side of the median plane (M) of the rim as the outer side (EXT) of the tire, the second sidewall (302) and the second bead (322) being arranged on the same side of the median plane (M) of the rim as the inner side (INT) of the tire, each first and second bead (321, 322) respectively comprising at least first and second circumferential reinforcing elements (331, 332) for anchoring the carcass layer (36) or at least one of the carcass layers (36), the first and second circumferential reinforcing elements (331, 332) being arranged substantially symmetrically with respect to the median plane (M) of the rim, the tire having an axial distance C1i,at the equator (E), between the median plane (M) of the rim and a first point (P3; P3') axially the outermost of each carcass layer i (36; 37) passing through the first sidewall (301), the tire having an axial distance C2i, at the equator (E), between the median plane (M) of the rim and a second point (P4; P4') axially the outermost of the carcass layer i (36; 37) passing through the second sidewall (302), the tire having an axial distance F1, at the equator (E), between the median plane (M) of the rim and a first point (P1) of a theoretical external surface (44) of the first sidewall, (301), the tire having an axial distance F2, at the equator (E), between the median plane (M) of the rim and a second point (P2) of the theoretical external surface (44) of the second sidewall (302), the tire having an axial thickness G1, at the equator (E), between a point (K1) of a theoretical internal surface (21) of an internal cavity (17) of the tire and a first axially innermost point (K3) of the axially innermost carcass layer (36) at the equator (E) passing through the first sidewall (301), the tire having an axial thickness G2, at the equator (E), between a point (K2) of a theoretical internal surface (21) of the internal cavity (17) of the tire and a second axially innermost point (K4) of the axially innermost carcass layer (36) at the equator (E) passing through the second sidewall (302), characterized in that 2 x F1 > LN with LN being the nominal axial width of the tire according to the ETRTO 2021 standard manual, in that |C1i-C2i| < 3.0 mm and in that F1 -C1 i > F2-C2i and in that G1 < 6.0 mm and / or G2 < 6.0 mm.

2. Tire (10) according to the preceding claim, in which |C1i-C2i| < 2.0 mm, preferably |C1i-C2i| < 1.0 mm and more preferably |C1i-C2i| < 0.5 mm.

3. A tire (10) according to any one of the preceding claims, wherein (F1-C1i)-(F2-C2i) > 2.0 mm, preferably (F1-C1i)-(F2-C2i) > 2.5 mm.

4. A tire (10) according to any one of the preceding claims, wherein (F1-C1i)-(F2-C2i) < 5.0 mm, preferably (F1-C1i)-(F2-C2i) < 3.0 mm.

5. A tire (10) according to any one of the preceding claims, wherein G1 < 4.0 mm and / or G2 < 4.0 mm, preferably G1 < 3.0 mm and / or G2 < 3.0 mm.

6. A tire (10) according to any one of the preceding claims, wherein |G1-G2| < 3.0 mm, preferably |G1-G2| < 2.0 mm, more preferably |G1-G2| < 1.0 mm and even more preferably |G1-G2| < 0.5 mm.

7. Tire (10) according to any one of the preceding claims, having an axial thickness E1, at the equator (E), between the first point (P1) of the theoretical external surface (44) of the first sidewall (301) and the first axially outermost point (P3) of the axially outermost carcass layer (36; 37) at the equator (E) such that E1 > 3.0 mm.

8. Tire (10) according to any one of the preceding claims, having an axial thickness E1 at the equator (E), between the first point (P1) of the theoretical external surface (44) of the first sidewall (301) and the first axially outermost point (P3) of the axially outermost carcass layer (36; 37) at the equator (E) such that E1 < 6.0 mm.

9. Tire (10) according to any one of the preceding claims, having an axial thickness E2, at the equator (E), between the second point (P2) of the theoretical external surface (44) of the second sidewall (302) and the second point axially outermost of the axially outermost carcass layer (36; 37) at the equator (E) such that E2 > 1.0 mm.

10. Tire (10) according to any one of the preceding claims, having an axial thickness E2, at the equator (E), between the second point (P2) of the theoretical external surface (44) of the second sidewall (302) and the second axially outermost point of the axially outermost carcass layer (36; 37) at the equator (E) such that E2 < 3.0 mm.

11. A tire (10) according to any one of the preceding claims, wherein 2 x F1 > LN + 0.5 mm, preferably 2 x F1 > LN + 1.0 mm, F1 and LN being expressed in mm 12. A tire (10) according to any preceding claim, comprising a tread surface (15) having an axial width LS such that LR-LS > 10.0 mm with LR being the reference width of the tread surface of the tire according to the ETRTO 2021 standard manual, LS being determined at 80% of the tire load capacity of the ETRTO 2021 standard manual and at a pressure of 2.5 bar.

13. Tire (10) according to any one of the preceding claims, comprising a first portion (311), called the shoulder portion, of the first sidewall (301) extending from a first axial edge (151) of the rolling surface (15) to the equator (E), the first shoulder portion (311) has a theoretical external surface (44) having a minimum radius of curvature greater than or equal to 25.0 mm.

14. Tire (10) according to any one of the preceding claims, comprising a first portion (311), called the shoulder portion, of the first sidewall (301) extending from a first axial edge (151) of the rolling surface (15) to the equator (E), the first shoulder portion (311) has a theoretical external surface (44) having a minimum radius of curvature Rmin less than or equal to 200.0 mm.

15. Tire (10) according to any one of the preceding claims, comprising a first portion (311), called the shoulder portion, of the first sidewall (301) extending from a first axial edge (151) of the rolling surface (15) to the equator (E), the first shoulder portion (311) has a theoretical external surface (44) having, outside the equator, a minimum radius of curvature Rmin, and at the equator (E) a radius of curvature RE such that Rmin > RE / 2.

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