TIRES FOR A HIGH-HEAD-SPEED MOTORCYCLE

Description

[0001] The present invention relates to a motorcycle tire.

[0002] We know of a tire designed for commuting (in English, this is called "commuting" or "commuter"). This designation is given because, although the tire's use is not limited to commuting, this type of use represents the majority of its applications. This tire is also suitable for cruiser or custom motorcycles.

[0003] Such a tire has dimensions and characteristics adapted to the motorcycle corresponding to the use or type of motorcycle previously described. Such dimensions adapted to commuting use or to "cruiser" or "custom" type motorcycles include a nominal aspect ratio H / S, expressed as a percentage, of at least 40 and at most 100, a nominal section width or sidewall size S of at least 50 mm and at most 240 mm, and a nominal hook diameter of at least 10 inches and at most 21 inches.

[0004] Furthermore, for such use, the tire must have a speed rating of V or lower. According to the "General Information" section of the European Tyre and Rim Technical Organisation (ETRTO) Standard Manual (2021), this speed rating corresponds to a maximum speed of 240 km / h. Indeed, for this type of use, speeds are relatively moderate. Nevertheless, it is necessary to have a sufficiently high maximum speed achievable by the tire, and therefore a sufficient speed rating, to guarantee the safety of tire users, particularly during occasional use of the tire at higher speeds (provided, of course, that these speeds do not exceed the tire's speed rating).

[0005] These tires are of the bias-belted type. These tire types are known in particular from the ETRTO Standard Manual, 2021.

[0006] A bias-ply tire with a belt comprises a crown, two sidewalls, and two bead ribs, each sidewall connecting each bead to the crown. The tire also includes a carcass reinforcement anchored in each bead and extending into each sidewall and radially inward to the crown. The carcass reinforcement includes a carcass layer with wire reinforcement elements forming an angle of +29° with the circumferential direction. The carcass reinforcement includes a radially external carcass layer with wire reinforcement elements forming an angle of -29° with the circumferential direction. The angles of each of the carcass layers are equal in absolute value but have opposite orientations. The crown comprises a crown reinforcement with one or more crown layers arranged radially outside the carcass reinforcement.In the case where the top reinforcement comprises two top layers, the top reinforcement includes a radially inner top layer with wire reinforcement elements forming an angle of +29° with the circumferential direction. The top reinforcement includes a radially outer top layer with wire reinforcement elements forming an angle of -29° with the circumferential direction. The angles of each of the top layers are equal in absolute value but have opposite orientations.

[0007] Unlike bias-ply tires with belts, a bias-ply tire does not include a crown reinforcement.

[0008] Diagonal and belted diagonal tires have speed ratings chosen from H, S, V, R, Q and P.

[0009] Although inexpensive due to a very simple manufacturing process and inexpensive materials, the diagonal type tire nevertheless has defects including its mass as well as its poor ability to maintain the expected radial dimension, whether during the application of inflation pressure which radially deforms the tire or during high-speed driving which also radially deforms the tire due to centrifugal force.

[0010] The bias-belted tire, although it has a superior capacity to maintain the expected radial dimension, nevertheless has an even greater mass than a bias-belted tire.

[0011] For their part, FR 3 102 097 A1 and FR 3 102 095 A1 each disclose a tire comprising a carcass reinforcement, as well as, at the top of the tire, a crown reinforcement including both a working reinforcement and a compression reinforcement. As for DE 600 20 498 T2, it discloses a bias-ply tire, the carcass reinforcement of which includes two crossed plies.

[0012] The invention aims to provide a tire with a reduced mass, an equivalent capacity to maintain the expected radial dimension compared to bias-belted and bias-belted tires described above, but without reducing the maximum speed attainable by the tire.

[0013] To this end, the invention relates to a motorcycle tire having a speed rating less than or equal to V and comprising a crown, first and second sidewalls, first and second bead ribs, each first and second sidewall connecting each first and second bead respectively to the crown, the tire comprising a carcass reinforcement anchored in each first and second bead and extending radially in each first and second sidewall and axially in the crown, the carcass reinforcement comprising a single layer of carcass, the crown comprising: a tread intended to come into contact with the ground during the rolling of the tire, a crown reinforcement arranged radially between the tread and the carcass reinforcement, the crown reinforcement comprising a single crown layer, The crown layer is axially delimited by the first and second axial edges of the crown layer and comprises crown wire reinforcement elements extending axially from the first axial edge to the second axial edge of the crown layer, substantially parallel to each other along a principal direction of each crown wire reinforcement element, forming an angle AT with the circumferential direction of the tire; the carcass layer is axially delimited by the first and second axial edges of the carcass layer and comprises carcass wire reinforcement elements extending axially from the first axial edge to the second axial edge of the carcass layer, each carcass wire reinforcement element extending along a principal direction of each carcass wire reinforcement element, forming an angle ACS with the circumferential direction of the tire.in a portion of the carcass layer extending axially radially above the top layer, the angle AT and the angle ACS being of opposite orientations and such that ||AT|-|ACS|| ≤ 5°. ,

[0014] The tires of the invention are intended for motorcycles as defined in the European Tyre and Rim Technical Organisation or "ETRTO" standard, 2021. Such a tire has a section in a meridian cutting plane characterized by a section height H, a nominal section width or flange size S, an overall tire width SG, in accordance with the European Tyre and Rim Technical Organisation or "ETRTO" standard, 2021.

[0015] According to the invention, the tire according to the invention has a speed rating defined according to the "General Information" section of the Standard Manual of the European Tyre and Rim Technical Organisation (ETRTO), 2021. A speed rating of V corresponds to a maximum speed of 240 km / h. This speed rating is present on the marking on the sidewall of the tire. Indeed, a tire generally has, on at least one of its sidewalls, a marking conforming to the marking in the ETRTO 2021 standard manual, indicating the tire size in the form W / M α KU β, where W designates the nominal section width, M designates the nominal aspect ratio, α designates the construction, K designates the nominal rim diameter, U designates the load index, and β designates the speed rating.

[0016] A speed rating of V or lower means that the tire has a speed rating corresponding to a maximum speed less than or equal to the maximum speed corresponding to a speed rating of V, which is 240 km / h. Such ratings are preferably chosen from the ratings P, Q, R, S, T, U, H, and V.

[0017] According to the invention, the crown reinforcement comprises a single crown layer. Thus, the crown reinforcement, with the exception of the crown layer, is devoid of any layer reinforced by wire reinforcement elements. Wire reinforcement elements of such reinforced layers excluded from the tire crown reinforcement include metallic wire reinforcement elements and textile wire reinforcement elements. Preferably, the crown reinforcement consists of the single crown layer.

[0018] According to the invention, the carcass reinforcement comprises a single layer of carcass. Thus, the carcass reinforcement, with the exception of this single layer of carcass, is devoid of any layer reinforced by wire reinforcement elements. The wire reinforcement elements of such reinforced layers excluded from the tire carcass reinforcement include metallic wire reinforcement elements and textile wire reinforcement elements. Preferably, the carcass reinforcement consists of the single layer of carcass.

[0019] The tire according to the invention has a reduced mass compared to bias-belted and bias-belted tires due to a smaller number of carcass reinforcement layers (compared to a bias-belted tire) and carcass and crown reinforcements (compared to a bias-belted tire).

[0020] The tire according to the invention also exhibits excellent ability to maintain its expected radial dimensions, whether under inflation pressure, which radially deforms the tire, or during high-speed driving. Indeed, due to its speed rating of V or less, corresponding to a maximum speed of 240 km / h (a relatively moderate speed), the tire according to the invention exhibits the same ability to maintain its expected radial dimensions as a bias-ply tire with a belt, in which the presence of two crown layers can ultimately be considered superfluous at relatively moderate speeds. Compared to a bias-ply tire, the tire according to the invention offers an improved ability to maintain its expected radial dimensions thanks to the presence of a single crown layer.

[0021] Surprisingly, the invention makes it possible to obtain a tire with the same achievable top speed as prior art tires. Indeed, even though the tire according to the invention has fewer layers and therefore, a priori, less mechanical strength, the tire according to the invention has an equal or even improved top speed. The inventors discovered that the high-speed degradation of prior art tires was not caused by insufficient mechanical strength of the tire structure but by significant heating of this structure, particularly at high speeds, leading first to thermal embrittlement of the structure, and then to its destruction.Thus, contrary to the natural approach of reinforcing the tire's structure, the inventors of this invention conceived the idea of ​​reducing the structure's heating to prevent thermal brittleness and the resulting destruction. By reducing the number of layers in the sidewalls (compared to a bias-ply tire) and in both the sidewalls and the crown (compared to a belted bias-ply tire), they reduce the tire's heating caused by sidewall and / or crown hysteresis when the tire is in motion, particularly at high speeds.

[0022] Regardless of whether the AT and ACS angles are constant or not over the entire portion of the tire axially between the axial edges of the top layer, the AT and ACS angles are of opposite orientations over the entire portion of the tire axially between the axial edges of the top layer.

[0023] The fact that the AT and ACS angles are substantially equal, i.e., ||AT|-|ACS|| ≤ 5°, allows the tire to be manufactured using a relatively simple process analogous to the manufacturing process for bias-ply tires. Indeed, thanks to the substantially equal AT and ACS angles, it is possible to lay up a carcass assembly and a crown assembly in which the carcass wire reinforcement elements and the crown wire reinforcement elements form substantially equal angles in absolute value with the circumferential direction of the manufacturing support, and to obtain, depending on the degree of conformation, the desired values ​​of the AT and ACS angles. Each carcass assembly and crown assembly is intended to form the single carcass layer and the single crown layer, respectively.

[0024] The characteristic ||AT|-|ACS|| ≤ 5° is observed for a given axial distance from the median plane. Thus, the angle pairs AT and ACS will be measured at points located, in a meridian cutting plane, at the same axial distance from the median plane M of the tire.

[0025] Finally, it should be noted that the tire according to the invention offers improved comfort compared to bias-ply tires or bias-ply tires with belts. The inventors explain this by the fact that, in prior art tires, the shear stress between the two carcass layers is relatively significant and results in relatively high vertical rigidity. In contrast, the tire according to the invention comprises only a single carcass layer, which eliminates shear stress and therefore significantly reduces vertical rigidity.

[0026] The tire according to the invention is a motorcycle tire. Such tires are preferably characterized by a curvature ratio ranging from 0.15 to 0.50, preferably from 0.20 to 0.40. A motorcycle tire, unlike a passenger car tire, has a highly curved tread with a distinctive, pronounced curvature. In particular, this curvature is characterized by the value of the curvature ratio H' / SG, where H' represents the radial height of the tread relative to the equatorial circumferential plane E passing through the radially outer ends of said tread, and SG represents the overall width of the tire, that is, the axial width measured at the equator on an unloaded tire mounted on a measuring rim and inflated to its nominal pressure.

[0027] Advantageously, the tires covered by the invention are such that the nominal aspect ratio (H / S), expressed as a percentage, is at least 40, preferably at least 65, and at most 100, preferably at most 80, and the nominal section width or bead size (S) is at least 50 mm, preferably at least 90 mm, and more preferably at least 100 mm and at most 240 mm, preferably at most 180 mm, more preferably at most 150 mm. Furthermore, the nominal hook diameter (D), defining the diameter of the tire mounting rim, is at least 10 inches, preferably at least 13 inches, and at most 21 inches, preferably at most 16 inches.

[0028] Axial direction refers to the direction substantially parallel to the main axis of the tire, that is, the axis of rotation of the tire.

[0029] By circumferential direction, we mean the direction which is substantially perpendicular to both the axial direction and to a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[0030] By radial direction, we mean 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.

[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 mid-axial distance of the two ribs and passes through the axial midpoint of the crown reinforcement.

[0032] The circumferential equatorial plane of the tire (denoted E) is defined, in a meridional cross-sectional plane, as the plane passing through the tire's equator, perpendicular to the median plane and the radial direction. The tire's equator, in a meridional cross-sectional plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), is the axis parallel to the tire's axis of rotation and passing through the outermost axial points of the tire when the unloaded tire is mounted on a measuring rim and inflated to its nominal pressure.

[0033] The height H of the tire is the radial distance between the outermost radial point of the tread intended to be in contact with the ground and the innermost radial point of the tire intended to be in contact with a support, for example a rim, when the unloaded tire is mounted on a measuring rim and inflated to its nominal pressure.

[0034] By meridian plane, we mean a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0035] The bead is the portion of the tire designed to allow the tire to be attached to a mounting surface, such as a wheel with a rim. Each bead is specifically designed to make contact with a hook on the rim, enabling it to be secured.

[0036] The principal direction in which a wire reinforcement element extends is understood to be the direction in which the wire reinforcement element extends along its greatest length. The principal direction in which a wire reinforcement element extends can be straight or curved; the reinforcement element can describe a straight or wavy path along its principal direction.

[0037] By portion of the assembly, layer or tire included axially between the axial edges of a wound assembly or layer or reinforcement, is understood a portion of the assembly, layer or tire extending axially and included between the radial planes passing through the axial edges of the wound assembly or layer or reinforcement.

[0038] By portion of a coiled set intended to extend axially, portion of a coiled set extending axially or portion of a layer extending axially in the radial perpendicularity of a reference set or a reference layer, is understood a portion of said set or of said layer contained between the radial projections of the axial edges of the reference set or of the reference layer onto said set or said layer.

[0039] Any range of values ​​designated by the expression "between a and b" represents the range of values ​​from more than a to less than b (i.e., bounds a and b excluded) while any range of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict bounds a and b).

[0040] Regarding each wire reinforcement element in the tire, the angle considered is the angle, in absolute value, the smaller of the two angles defined between the reference line, here the circumferential direction of the tire, and the principal direction along which the wire reinforcement element considered extends.

[0041] Regarding each wire reinforcement element, in the pneumatic and during the process, by orientation of an angle, we mean the direction, clockwise or counterclockwise, in which it is necessary to turn from the reference line, here the circumferential direction of the support, the assembly or the pneumatic, defining the angle to reach the main direction in which the wire reinforcement element considered extends.

[0042] For each wire reinforcement element, during the process, the angles formed by the principal directions along which the top and carcass wire reinforcement elements extend are conventionally angles of opposite orientations. The angle formed by the principal direction along which each top wire reinforcement element extends is, in absolute value, the smaller of the two angles defined between the reference line (here, the circumferential direction of the support, assembly, or tire) and the principal direction along which the top wire reinforcement element extends. Thus, the angle formed by the principal direction along which each top wire reinforcement element extends defines an orientation that is opposite to that formed by the angle of the principal direction along which each carcass wire reinforcement element extends.

[0043] In the tire according to the invention, the crown comprises the tread and the crown reinforcement. The tread is defined as a band of polymeric material, preferably elastomeric, delimited by: radially outwards, by a surface intended to be in contact with a ground and radially inwards, by the top reinforcement.

[0044] The polymeric material strip consists of a layer of a polymeric material, preferably elastomeric, or of a stack of several layers, each layer being made of a polymeric material, preferably elastomeric.

[0045] In a highly preferred embodiment, the crown comprises a single crown reinforcement. Thus, the crown, with the exception of the crown reinforcement, is devoid of any reinforcement made with wire reinforcement elements. Wire reinforcement elements in such excluded crown reinforcements include metallic wire reinforcement elements and textile wire reinforcement elements. In a highly preferred embodiment, the crown consists of the tread and the crown reinforcement.

[0046] In a highly preferred embodiment, the carcass reinforcement is arranged directly radially in contact with the apex reinforcement and the apex reinforcement is arranged directly radially in contact with the tread.

[0047] By directly radially in contact, we understand that the objects considered directly radially in contact with each other, here the reinforcements and the tread, are not separated radially by any object, for example by any layer, reinforcement or strip that would be interposed radially between the objects considered directly radially in contact with each other.

[0048] In embodiments in which the main direction of each wire reinforcement element of the carcass has transition zones where the angle is substantially variable, the portion of the carcass layer extending axially in the radial perpendicularity of the top layer and whose angle ACS is characterized has a curvilinear width along the axial direction equal to at least 30%, preferably at least 40% of the curvilinear width along the axial direction of the top layer.

[0049] In embodiments in which the main direction of each wire reinforcement element of the carcass has transition zones where the angle is substantially variable, the portion of the carcass layer extending axially in the radial perpendicularity of the top layer and whose angle ACS is characterized has a curvilinear width along the axial direction equal to at most 90%, preferably at most 80% of the curvilinear width along the axial direction of the top layer.

[0050] Preferably, the median plane of the tire intersects this portion of the carcass layer extending axially below the crown layer. More preferably, this portion of the carcass layer extending axially below the radial crown layer is axially centered on the median plane of the tire.

[0051] The curvilinear width along the axial direction refers to the width measured in a meridional cross-section between the two axial edges of the corresponding layer, following the curvature of said layer, for example, along a curved line passing through the midpoint of the radial thickness of said layer. This width is called curvilinear in contrast to the straight width, which would be measured between the two axial edges of the layer parallel to the axis of rotation of the tire between the two axial edges.

[0052] In an embodiment relating to relatively high speed indices, the speed index is chosen from the indices V, H, U, T, S.

[0053] In an embodiment relating to relatively low speed indices, the speed index is chosen from the indices S, R, Q, P.

[0054] In optional and advantageous embodiments, each angle AT and ACS ranges, in absolute value, from 20° to 65°, preferably from 26° to 55°, and even more preferably from 26° to 45°. Thus, unlike a tire in which the angles AT and / or ACS would be smaller in absolute value, and in which the crown would exhibit high flexural rigidity and torsional rigidity, the tire in these embodiments has a relatively flexible crown due to the relatively large angles AT and ACS. Therefore, unlike a rigid crown which, during excitation, for example when cornering, would cause high vibrations of the tire, the tire in these embodiments dampens vibrations thanks to the flexibility of its crown.

[0055] In embodiments defining a method of anchoring the carcass layer in each bead of the tire, each first and second bead comprising respectively a first and second circumferential reinforcement element, the carcass layer comprises: an axially inner portion extending from a first radially innermost point of the carcass layer to the first circumferential reinforcement element to a second radially innermost point of the carcass layer to the second circumferential reinforcement element, and first and second axially outer portions, each first and second axially outer portion being arranged axially outside the axially inner portion and extending respectively from each first and second radially innermost point to each first and second circumferential reinforcement element to each first and second axial edges of the carcass layer, respectively the axially inner portion and the first and second axially outer portions being arranged so as to form first and second windings around respectively each first and second circumferential reinforcement element.

[0056] Other methods of anchoring the carcass layer are possible, for example as described in US5702548.

[0057] In embodiments that optionally and advantageously provide significant lateral rigidity, particularly compared to radial tires, the inner axial portion and the first and second outer axial portions are arranged to form: a first carcass layer cover zone comprising a portion of the inner axial portion and the first outer axial portion arranged axially opposite each other, and a second carcass layer cover zone comprising a portion of the inner axial portion and the second outer axial portion arranged axially opposite each other, and the main direction of each carcass wire reinforcement element forms, with the circumferential direction of the tire, in each part of the axially inner portion and each first and second axially outer portion of each first and second overlap zone, an angle ACF1, in absolute value less than or equal to 70°.

[0058] The fact that the ACF1 angle is, in absolute value, less than or equal to 70° gives the tire relatively high lateral rigidity compared to a radial tire, whose ACF1 angles are generally greater than or equal to 80°. The tire thus exhibits significantly greater drift rigidity than a radial tire.

[0059] Advantageously, angle ACF1 is less than or equal to 65°, preferably less than or equal to 60°.

[0060] Advantageously, angle ACF1 is greater than or equal to 25°, preferably greater than or equal to 30°.

[0061] Due to the manufacturing process usually used, the angle ACF1 of each part of the axially inner portion of each first and second overlap zone is oriented opposite to the angle ACF1 respectively of each first and second axially outer portion of each first and second overlap zone.

[0062] Optionally, the axially inner portion includes first and second portions inserted respectively between: the portion of the axially inner part of each first and second overlap zone, and the portion of the carcass layer extending axially radially above the top layer, the main direction of each carcass wire reinforcement element, forming, with the circumferential direction of the tire, in each first and second intercalated portion, an angle ACF2, in absolute value, greater than or equal to ACF1 and strictly greater than ACS, preferably strictly greater than ACF1 and ACS.

[0063] In embodiments in which the main direction of each wire reinforcement element of the carcass has transition zones where the angle is substantially variable, each first and second intercalated portion extending radially in each flank has a curvilinear height along the radial direction equal to at least 5%, preferably at least 15% and more preferably at least 30% of the curvilinear height LR along the radial direction of each part of the axially internal portion of the carcass layer extending from respectively each first and second axially external end of the portion of the carcass layer extending axially radially from the top layer to respectively each first and second radially external end of each first and second overlap zone.

[0064] In embodiments in which the main direction of each wire reinforcement element of the carcass has transition zones where the angle is substantially variable, each first and second intercalated portion extending radially in each flank has a curvilinear height along the radial direction equal to at most 90%, preferably at most 80% of the curvilinear height LR along the radial direction of each part of the axially internal portion of the carcass layer extending from respectively each first and second axially external end of the portion of the carcass layer extending axially radially from the top layer to respectively each first and second radially external end of each first and second overlap zone.

[0065] By curvilinear height along the radial direction, we mean the height measured in a meridional cross-sectional plane along the curvature of the layer, for example, along a curved line passing through the midpoint of the radial thickness of the layer. This height is called curvilinear in contrast to the straight height, which would be measured between the two ends of the portion parallel to the radial direction of the tire.

[0066] Advantageously, the ACF2 angle is, in absolute value, less than or equal to 80°, preferably ranging, in absolute value, from 35° to 70°, and more preferably from 40° to 60°. The lower the ACF2 angle in absolute value, the higher the sidewall flexural rigidity and torsional rigidity. Since these high rigidities are compensated by relatively low sidewall flexural rigidity and torsional rigidity at the crown, the tire generates little or no vibration.

[0067] In a first embodiment allowing optimization of the reduction of the mass of the tire by reducing the length of the first and second axially external portions, each first and second axial edge of the carcass layer is located radially inside the equator of the tire and, preferably, located radially inside the equator of the tire at a radial distance from the equator greater than or equal to 50% of the radial distance between the equator and the most radially internal point of the tire.

[0068] In a second embodiment allowing improvement of the drift stiffness compared to the first embodiment of each first and second axial edge of the carcass layer, each first and second axial edge of the carcass layer is located radially on or outside the equator of the tire and preferably located radially outside the equator of the tire at a radial distance from the equator less than or equal to 50% of the radial distance between the equator and the outermost radial point of the tire.

[0069] In certain variants of the second embodiment, it may be envisaged that each first and second axial edge of the carcass layer is located radially outside the equator of the tire and axially inside respectively each first and second axial edge of the crown layer.

[0070] Optionally and advantageously, in order to improve performance in the regulatory breaking energy test or "Breaking Energy Test", the ratio of the breaking strength of the top layer to the breaking strength of the carcass layer is strictly greater than 1, preferably from 1.10 to 1.45 and more preferably from 1.25 to 1.35.When a diagonal tire is subjected to the burst energy test, the radially outer carcass layer is the layer that breaks first, firstly because the wire reinforcement elements of this radially outer layer are subjected to significantly greater stresses than those to which the wire reinforcement elements of the radially inner carcass layer are subjected, due to its radially outer position and, secondly, due to the presence of a thickness of elastomeric material between the two layers which protects, through its shear when subjected to the burst energy test, the radially inner carcass layer.In other words, the radially outer carcass layer is the fusible layer and, in state-of-the-art tires, the resistance potential of the assembly formed by the two radially inner and outer carcass layers is not fully exploited.

[0071] By increasing the tensile strength of the top layer, which is the fusible layer, the point at which the top layer breaks is delayed. This synergistic approach benefits from the improved performance of the top and carcass layers and the increased strength of the top layer, which is the fusible layer. The optimal ratio between the tensile strength of the top layer and the tensile strength of the carcass layer depends primarily on the AT and ACS angles. Therefore, the larger the AT and ACS angles, the higher the ratio should be. Conversely, the smaller the AT and ACS angles, the lower the preferred ratio. A person skilled in the art will be able to determine the optimal ratio based on the chosen AT and ACS angles, if necessary through successive tests by varying the mechanical strengths of each of the top and carcass layers.

[0072] To determine the mechanical resistance of a layer expressed in daN / mm, the breaking strength of a wire reinforcement element of the layer is measured, for example according to the ASTM D 885 / D 885M - 10a of 2014 standard. Then, the breaking strength of the wire reinforcement element is multiplied by the density of wire reinforcement elements per unit width of the web intended to form the layer, here by the number of wire reinforcement elements per mm of web intended to form the layer, this number being determined along a direction perpendicular to the direction in which the wire reinforcement elements extend in the web intended to form the layer.Mechanical strengths, and in particular the densities of wire reinforcement elements in each of the crown and carcass layers, are measured before the deformation stage on each ply intended to form the corresponding layer, or alternatively, on the tire layers themselves, taking into account the degree of conformation, in order to determine the density of wire reinforcement elements in each of the crown and carcass layers before the deformation stage. Finally, regarding the ratio of the rupture strength of the crown layer to the rupture strength of the carcass layer, it does not matter whether it is determined by taking the densities before or after the deformation stage, as the ratio remains constant.

[0073] In preferred embodiments that provide an excellent compromise between the mechanical strength of the top layer, particularly its burst pressure, cost, and mass: The top layer has a tensile strength greater than or equal to 1900 daN / dm, preferably greater than or equal to 2300 daN / dm. The top layer has a tensile strength less than or equal to 2600 daN / dm.

[0074] In preferred embodiments that provide an excellent compromise between the mechanical strength of the carcass layer, particularly its burst pressure, cost, and mass: The carcass layer has a tensile strength greater than or equal to 1600 daN / mm, preferably greater than or equal to 1800 daN / mm. The carcass layer has a tensile strength less than or equal to 2300 daN / mm, preferably less than or equal to 2100 daN / mm.

[0075] In preferred embodiments that allow for the reduction of tire weight, each top and carcass wire reinforcement element comprises an assembly of several elementary textile monofilaments.

[0076] In a preferred embodiment, the top and carcass wire reinforcement elements are identical and, in order to differentiate the breaking strengths of the top layer and the carcass layer, the ratio of the density of top wire reinforcement elements to the density of carcass wire reinforcement elements is strictly greater than 1, preferably from 1.10 to 1.45 and more preferably from 1.25 to 1.35.

[0077] An elementary monofilament is defined as a monolithic filament made from a given material and produced, for example, by spinning that material, such as melt spinning, solution spinning, or gel spinning. Elementary monofilaments typically have diameters ranging from 2 µm to 0.50 mm. They are assembled into strands comprising at least two elementary monofilaments, typically more than ten, preferably more than 100, and even more preferably more than 200. A textile elementary monofilament is defined as a non-metallic elementary monofilament.

[0078] The invention and its advantages will be readily understood in light of the detailed description and non-limiting embodiments that follow, as well as Figures 1 to 16 relating to these examples, in which: there figure 1is a cross-sectional view in a meridional cutting plane of a tire according to a first embodiment of the invention, the figure 2 is a schematic cutaway view of the tire of the figure 1 illustrating the arrangement of the wire reinforcement elements of the top and carcass layers radially above the top layer, the figure 3 is a schematic view of the carcass wire reinforcement elements arranged in the sidewall of the tire of the figure 1 , THE figures 4 to 12 illustrate the different stages of a process for manufacturing the tire of the figure 1 , and the figure 13 is a view analogous to that of the figure 1 of a tire according to a second embodiment of the invention.

[0079] In the figures relating to the tire, a coordinate system X, Y, Z is shown corresponding to the usual axial (X), radial (Y), and circumferential (Z) directions of a tire. In the figures relating to the process, a coordinate system x, y, z is shown corresponding to the usual axial (x), radial (y), and circumferential (z) directions of a manufacturing support having a substantially cylindrical shape about a principal axis A. These axial (x), radial (y), and circumferential (z) directions are also used to refer to the axial (x), radial (y), and circumferential (z) directions of a raw blank and the assembly having substantially cylindrical and toroidal shapes about a principal axis A'.

[0080] In the description that follows, particularly regarding the figure 1A half-tire is shown, with part numbers for both sides included for clarity. For example, "the tire includes first and second beads 24A, 24B" means that the tire has, on one side of the median plane, the first bead 24A, and on the other side of the median plane, the second bead 24B. The reader will be able to identify the relevant part numbers, which include 18A, 18B, 24A, 24B, 26A, 26B, 34A, 34B, 34GA, 34GB, 34EA, 34EB, 34ITA, 34ITB, 35A, 35B, 37A, 37B, 39A, and 39B.

[0081] We have represented on the figure 1A tire, according to the invention and designated by the general reference 10. The tire 10 is substantially of revolution about an axis substantially parallel to the axial direction X. The tire 10 is intended here for a motorcycle for commuting use and has dimensions 150 / 70 - 14. The tire 10 has a speed rating selected from among the ratings V, H, U, T, S and here equal to S. Being intended for a motorcycle, the tire is characterized in particular by a curvature ratio ranging from 0.15 to 0.50, preferably ranging from 0.20 to 0.40 and here equal to 0.33.

[0082] The tire 10 includes a crown 12 comprising a tread 20 intended to come into contact with a ground during rolling and a crown reinforcement 14 extending into the crown 12 in the circumferential direction Z. The tire 10 also includes a sealing layer 16 for an inflation gas intended to delimit an internal closed cavity with a mounting support for the tire 10 once the tire 10 is mounted on the mounting support, for example a rim.

[0083] The vertex 12 comprises a vertex reinforcement 14 consisting of a single vertex layer 18 and, in this case, is made up of the single vertex layer 18. For the sake of simplicity, we will refer to the vertex layer 18 without repeatedly stating that this layer is unique. The vertex reinforcement 14 is radially surmounted by the tread 20.

[0084] The tire 10 comprises first and second sidewalls 22A, 22B extending radially inward from the apex 12. The tire 10 further comprises first and second bead 24A, 24B radially inward from the first and second sidewalls 22A, 22B, respectively. Each first and second sidewall 22A, 22B connects each first and second bead 24A, 24B, respectively, to the apex 12.

[0085] Each first and second bead 24A, 24B includes respectively at least one first and second circumferential reinforcement element 26A, 26B, in this case a rod 28 radially surmounted by a mass of rubber 30 for stuffing.

[0086] The tire 10 includes a carcass reinforcement 32 anchored in each first and second bead 24A, 24B. The carcass reinforcement 32 extends radially in each first and second sidewall 22A, 22B and axially in the crown 12. The crown reinforcement 14 is arranged radially between the tread 20 and the carcass reinforcement 32.

[0087] The frame structure 32 comprises a single layer of frame 34 and in this case, consists of the single layer of frame 34. For the sake of simplicity, we will refer to the layer of frame 34 without mentioning each time that this layer is unique.

[0088] Each top layer 18 and carcass 34 comprises an elastomeric matrix in which one or more wire reinforcement elements of the corresponding layer are embedded. These layers will now be described with reference to the figures 1 to 3 .

[0089] The top layer 18 is axially delimited by the first and second axial edges 18A and 18B of the top layer 18. The top layer 18 comprises top wire reinforcement elements 180 extending axially from the first axial edge 18A to the second axial edge 18B of the top layer 18, substantially parallel to each other. Each top wire reinforcement element 180 extends along a principal direction D2. The direction D2 forms, with the circumferential direction Z of the tire 10, an angle AT, in absolute value, ranging from 20° to 65°, preferably from 26° to 55°, and even more preferably from 26° to 45°. Here AT = -29°.

[0090] The carcass layer 34 is axially delimited by the first and second axial edges 34A, 34B of the carcass layer 34. The carcass layer 34 comprises wire reinforcement elements 340 extending axially from the first axial edge 34A to the second axial edge 34B of the carcass layer 34. Each wire reinforcement element 340 extends along a principal direction D3, forming, with the circumferential direction Z of the tire 10, an angle ACS, in absolute value, ranging from 20° to 65°, preferably from 26° to 55°, and even more preferably from 26° to 45°, in a portion 34S of the carcass layer 34 extending axially along the radial axis of the top layer 18. Here, ACS=+29°.

[0091] The portion 34S of the carcass layer 34 extending axially above the top layer 18 has a curvilinear width LS along the axial direction equal to at least 30%, preferably at least 40%, of the curvilinear width LA along the axial direction of the top layer 18, and equal to at most 90%, preferably at most 80%, of the curvilinear width LA along the axial direction of the top layer 18. Here, LS / LA = 0.75. The median plane M of the tire 10 intersects this portion 34S. More preferably, this portion 34S is axially centered on the median plane M of the tire 10.

[0092] The carcass layer 34 comprises an axially inner portion 34I extending from a first radially innermost point 35A of the carcass layer 34 to the first circumferential reinforcement element 26A to a second radially innermost point 35B of the carcass layer 34 to the second circumferential reinforcement element 26B. The carcass layer 34 also comprises first and second axially outer portions 34EA, 34EB, each first and second axially outer portion 34EA, 34EB being arranged axially outside the axially inner portion 34I and extending respectively from each first and second radially innermost point 35A, 35B to each first and second circumferential reinforcement element 26A, 26B to each first and second axial edges 34A, 34B of the carcass layer 34.

[0093] The axially inner portions 34I and axially outer portions 34EA, 34EB are arranged to form first and second windings 37A, 37B around each first and second circumferential reinforcement element 26A, 26B respectively. The rubber packing mass 30 is intercalated axially between the axially inner portion 34I and the first and second axially outer portions 34EA, 34EB.

[0094] The axially inner portion 34I and the first axially outer portion 34EA are arranged to form a first overlap zone 39A of the carcass layer 34, comprising a portion 34ITA of the axially inner portion 34I and the first axially outer portion 34EA arranged axially opposite each other. The axially inner portion 34I and the second axially outer portion 34EB are arranged to form a second overlap zone 39B of the carcass layer 34, comprising a portion 34ITB of the axially inner portion 34I and the second axially outer portion 34EB arranged axially opposite each other.

[0095] In each section 34ITA and 34ITB of the axially inner portion 34I of each first and second overlap zone 39A, 39B, and in each first and second axially outer portion 34EA, 34EB of each first and second overlap zone 39A, 39B, the principal direction D3 of each carcass wire reinforcement element 340 forms, with the circumferential direction Z of the tire 10, an angle ACF1, in absolute value less than or equal to 70°, preferably 65° and more preferably 60°, and greater than or equal to 25°, preferably 30°. In this case, ACF1 varies from +52° to +47°. It should be noted that the orientation of angle ACF1 in each section 34ITA, 34ITB is opposite to the orientation of angle ACF1 in each portion 39A, 39B.

[0096] The axially internal portion 34I comprises first and second intercalated portions 34GA, 34GB respectively between the part 34ITA, 34ITB of the axially internal portion 34I of each first and second overlap zone 39A, 39B, and the portion 34S of the carcass layer 34 extending axially radially from the top layer 18.

[0097] In each first and second intercalated portion 34GA, 34GB, the principal direction D3 of each carcass wire reinforcement element 340 forms, with the circumferential direction Z of the tire 10, an angle ACF2, in absolute value, strictly greater than ACF1 and ACS. The angle ACF2 is, in absolute value, less than or equal to 80°, preferably ranging, in absolute value, from 35° to 70° and more preferably from 40° to 60°. In this case, the angle ACF2 varies from +40° to +52°.

[0098] Each first and second intercalated portion 34GA, 34GB extending radially in each first and second flank 22A, 22B has a curvilinear height LF along the radial direction equal to at least 5%, preferably at least 15% and more preferably at least 30% of the curvilinear height LR along the radial direction of each part 34L of the axially internal portion 34I of the carcass layer 34 extending from respectively each first and second axially external end of the portion 34S of the carcass layer 34 extending axially radially from the top layer 18 to respectively each first and second radially external end of each first and second overlap zone 39A, 39B.Each first and second intercalated portion 34GA, 34GB extending radially into each first and second flank 22A, 22B has a curvilinear height LF along the radial direction equal to at most 90%, preferably at most 80% of the curvilinear height LR along the radial direction of each part 34L of the axially internal portion 34I of the carcass layer 34. Here, LF / LR=0.75.

[0099] In this first embodiment, each first and second axial edge 34A, 34B of the carcass layer 34 is located radially inside the equator E of the tire 10 and, preferably, located radially inside the equator E of the tire 10 at a radial distance C1 from the equator E greater than or equal to 50% of the radial distance E1 between the equator E and the innermost radial point of the tire 10. In this case, E1=55 mm and C1=32 mm.

[0100] As illustrated on the figure 2The angles AT and ACS have opposite orientations and such that ||AT|-|ACS|| ≤ 5° for any pair of points in the vertex layer 18 and the frame layer 34 located at the same axial distance from the median plane M and belonging to the same meridian cutting plane. Here, for any pair of points in the vertex layer 18 and the frame layer 34 located at the same axial distance from the median plane M and belonging to the same meridian cutting plane, ||AT|-|ACS|| = ||-29|-|+29||=|29-29|=0° ≤ 5°.

[0101] The top 180 and carcass 340 wire reinforcement elements are identical. In this case, each top 180 and carcass 340 wire reinforcement element comprises an assembly of several elementary textile monofilaments chosen from elementary monofilaments of aliphatic polyamide, elementary monofilaments of polyester or elementary monofilaments of cellulosic derivatives and assemblies of these elementary monofilaments, preferably chosen from elementary monofilaments of aliphatic polyamide, elementary monofilaments of polyester and assemblies of these elementary monofilaments. In this case, each wire reinforcement element with a top diameter of 180 and a carcass diameter of 340 is an assembly of two strands of HMLS grade polyethylene terephthalate, each with a count of 144 tex, individually twisted at 420 turns / meter in one direction and then collectively at 420 turns / meter in the other direction.

[0102] The ratio of the density d2 of top wire reinforcement elements to the density d3 of carcass wire reinforcement elements is strictly greater than 1, preferably ranging from 1.10 to 1.45 and more preferably from 1.25 to 1.35. Here, d2 / d3 = 1.29. Indeed, the top layer 18 has a density d2 of top wire elements 180 equal to 139 wires per decimeter of top layer 18. The carcass layer 34 has a density d3 of carcass wire elements 340 equal to 108 wires per decimeter of carcass layer 34.

[0103] The top layer 18 has a tensile strength Rs greater than or equal to 1900 daN / dm, preferably greater than or equal to 2300 daN / dm and less than or equal to 2600 daN / dm. The carcass layer 34 has a tensile strength Rc greater than or equal to 1600 daN / mm, preferably greater than or equal to 1800 daN / mm and less than or equal to 2300 daN / mm, preferably less than or equal to 2100 daN / mm. In this case, Rs = 2475 daN / dm and Rc = 1920 daN / dm. It should be noted that since the wire reinforcement elements of the top 180 and carcass 340 are identical, the mechanical resistances Rs and Rc also satisfy the condition that the ratio of the breaking strength Rs of the top layer 18 to the breaking strength Rc of the carcass layer 34 is strictly greater than 1, preferably from 1.10 to 1.45 and more preferably from 1.25 to 1.35. Here Rs / Rc=d2 / d3=1.29.

[0104] The tire 10 is obtained by a process according to a first embodiment which will be described with reference to figures 4 to 12 .

[0105] First, a rolled top assembly 50 and a rolled frame assembly 52 are manufactured by arranging the wire reinforcement elements 180 and 340 of each assembly 50 and 52 parallel to each other and embedding them, for example by calendering, in a non-crosslinked composition comprising at least one elastomer, the composition being intended to form an elastomeric matrix once crosslinked. This results in a so-called straight sheet, in which the wire reinforcement elements are parallel to each other and to the principal direction of the sheet. Then, if necessary, portions of each straight sheet are cut at a cutting angle and these portions are joined together to obtain a so-called angled sheet, in which the wire reinforcement elements of the sheet are parallel to each other and form an angle with the principal direction of the sheet equal to the cutting angle.In this case, in the first embodiment, an angled sheet is formed only for the top sheet, the carcass sheet advantageously not requiring cutting in this first embodiment.

[0106] In the described embodiment, we obtain on the one hand a single top sheet 49 and a single carcass sheet 51 whose axial width of each, that is to say the dimension along a direction perpendicular to the longitudinal edges of each sheet, is equal to the axial width respectively of each set of rolled top 50 and rolled carcass 52 which will be formed subsequently.

[0107] With reference to the figure 4 , in a first step of assembling a raw blank, a sealing sheet 70 is formed by winding a support 60 having a substantially cylindrical shape around its main axis A, a wound sealing assembly 72 intended to form the sealing layer 16.

[0108] Then, with reference to the figure 5Radially outside the wound sealing assembly 72, the wound carcass layer 51 is wound around the support 60 to form the wound carcass layer 34. The wound carcass layer 52 is axially delimited by the first and second axial edges 52A, 52B of the wound carcass layer 52 and comprises the wire reinforcement elements of the carcass 340 extending substantially parallel to each other axially from the first axial edge 52A to the second axial edge 52B of the wound carcass layer 52. Each wire reinforcement element of the carcass 340 extends, within the carcass layer 51, along a principal direction K3 of each wire reinforcement element of the carcass 340 within the carcass layer 51. The principal direction K3 forms, with the direction circumferential z of support 60, an initial angle A3 of each wire reinforcement element of frame 340, here equal, in absolute value, to 52°.

[0109] With reference to figures 6 to 8 , then, the first and second circumferential reinforcement elements 26A, 26B are arranged around the rolled carcass assembly 52 and each first and second axial edge 52A, 52B of the rolled carcass assembly 52 is turned axially inwards so as to radially cover each first and second circumferential reinforcement element 26A, 26B respectively by each first and second axial edge 52A, 52B of the rolled carcass assembly 52 and so that the rolled carcass assembly 52 is wrapped around each first and second circumferential reinforcement element 26A, 26B.

[0110] We have represented on the figure 8 a diagram illustrating the arrangement of the wire reinforcement elements 340 of the carcass at the end of the axial turning step of the first and second axial edges 52A, 52B of the carcass assembly wrapped 52 around the first and second circumferential reinforcement elements 26A, 26B.

[0111] Then, with reference to Figures 9 and 10 By winding the top sheet 49 radially outside the wound frame assembly 52, the wound top assembly 50 is formed, which will form the top layer 18. The wound top assembly 50 is axially delimited by the first and second axial edges 50A, 50B of the wound top assembly 50 and comprises the wire reinforcement elements of the top 180 extending substantially parallel to each other axially from the first axial edge 50A to the second axial edge 50B of the wound top assembly 50. Each wire reinforcement element of the top 180 extends, within the top sheet 49, along a principal direction K2 of each wire reinforcement element of the top 180 within the top sheet 49. With reference to the Figure 10, the main direction K2 forms, with the circumferential direction z of the support 60, an initial angle A2 of each wire reinforcement element with vertex 180, here equal, in absolute value, to 52°.

[0112] The wrapped sealing assembly 72, the wrapped carcass assembly 52 and the wrapped top assembly 50 then form an assembly 58 of substantially cylindrical shape around a main axis A' of the assembly substantially coincident with the main axis A of the support 60.

[0113] We have represented on the Figure 10 a scheme similar to that of the figure 8 illustrating the arrangement of the 340 carcass wire reinforcement elements and the 180 apex wire reinforcement elements at the end of the formation step of the wrapped apex assembly 50. On this Figure 10 , we have represented the initial angles A2 and A3.

[0114] In a portion AC of the assembly 58 located axially between the axial edges 50A, 50B of the wrapped vertex assembly 50, the initial angles A2 and A3 are such that ||A2|-|A3|| ≤ 5° and have opposite orientations. In this case, A2=-52° and A3=+52°.

[0115] Then, by winding one or more tread sheets radially outside the wound top assembly, a wound tread assembly is formed to form the tread 20. A raw blank 11 of the tire is then obtained, intended to be cross-linked in the cross-linking mold.

[0116] Next, the raw blank 11, comprising the assembly 58 and formed from this assembly 58, is transferred from the support 60 into a curing mold comprising an internal cavity (not shown). Once in the curing mold, the raw blank 11, and therefore also the assembly 58, which is substantially cylindrical in shape, is deformed so as to obtain the raw blank 11 with a substantially toroidal shape, and thus the assembly 58 also with a substantially toroidal shape around the principal axis A' of the assembly 58. The deformation step of the blank 11, and therefore of the assembly 58, is thus carried out in the curing mold, for example by pressurizing a membrane inside the raw blank 11. The resulting deformed blank 11 is illustrated in the diagrams. Figures 11 and 12 .

[0117] With reference to the figure 12The assembly 58, which is substantially cylindrical in shape, is deformed around the principal axis A' of the assembly 58 so as to obtain the assembly 58, which is substantially toroidal in shape around this principal axis A', such that, after the deformation step, the principal direction K3 of each wire reinforcement element of the frame 340 forms, with the circumferential direction z of the assembly 58, a final angle B3S of each wire reinforcement element of the frame 340, in absolute value, equal to 29°, in a portion 52S of the wound frame assembly 52 extending axially radially from the wound top assembly 50. The portion 52S of the wound frame assembly 52 is intended to form the portion 34S of the frame layer 34.

[0118] The assembly 58, substantially cylindrical in shape, is deformed around the principal axis A' of the assembly 58 so as to obtain the assembly 58, substantially toric in shape, around this principal axis A' also, so that, subsequent to the deformation step, the principal direction K3 of each wire reinforcement element of the carcass 340 forms, with the circumferential direction z of the assembly 58, a final angle B3F1 of each wire reinforcement element of the carcass 340 varying from 47° to 52°, in portions and parts 52ITA, 52ITB, 52EA, 52EB intended to form respectively the parts and portions 34ITA, 34ITB, 34EA, 34EB of the axially internal portion 34I of the carcass layer 34.

[0119] The assembly 58, which is substantially cylindrical in shape, is deformed around the principal axis A' of the assembly 58 so as to obtain the assembly 58, which is substantially toric in shape around this principal axis A' also, so that, after the deformation step, the principal direction K3 of each wire reinforcement element of the frame 340 forms, with the circumferential direction z of the assembly 58, a final angle B3F2 of each wire reinforcement element of the frame 340 substantially equal to the angle ACF2, here equal to 52°, in portions 52GA, 52GB intended to form respectively the portions 34GA, 34GB of the axially internal portion 34I of the frame layer 34.

[0120] The assembly 58, which is substantially cylindrical in shape, is deformed around the principal axis A' of the assembly 58 so as to obtain the assembly 58, which is substantially toric in shape around this principal axis A' also, so that, after the deformation step, the principal direction K2 of each wire reinforcement element with vertex 180 forms, with the circumferential direction z of the assembly 58, a final angle B2 of each wire reinforcement element with vertex 180, in absolute value, equal to 29°.

[0121] As depicted on the figure 12 The angles B2 and B3S are such that ||B2|-|B3S|| ≤ 5° and have opposite orientations. In this case, B2=-29° and B3S=+29°.

[0122] During the deformation stage, angles B2, B3S and B3F1 vary according to a law of variation known to those skilled in the art, depending in particular on the initial angles A2 and A3 as well as the deformation rate, and as explained in FR2797213 and in FR1413102. Conversely, angle B3F2 does not vary and is approximately equal to angle A3.

[0123] We will now describe a pneumatic system and a method according to a second embodiment of the invention. Elements analogous to those of the first embodiment are designated by identical reference numerals.

[0124] Unlike the pneumatic 10 according to the first embodiment and as illustrated on the figure 13, each first and second axial edge 34A, 34B of the carcass layer 34 is located radially outside the equator E and here located radially on or outside the equator E at a radial distance C2 from the equator E less than or equal to 50% of the radial distance E2 between the equator E and the most radially outside point of the tire 10. In this case, each first and second axial edge 34A, 34B of the carcass layer 34 is located radially on the equator E of the tire 10. In this case, E2=52 mm and C2=0 mm.

[0125] Furthermore, unlike the first embodiment in which all the top 180 and carcass 340 wire reinforcement elements are identical, the top 180 wire reinforcement elements are different from the carcass 340 wire reinforcement elements. Each wire reinforcement element of the top 180 layer comprises an assembly of several elementary textile monofilaments selected from aromatic polyamide elementary monofilaments and assemblies of these aromatic polyamide elementary monofilaments with textile elementary monofilaments other than aromatic polyamide textile elementary monofilaments. In this case, each top 180 wire reinforcement element is an assembly of two strands of aromatic polyamide, for example aramid, each having a fiber count of 167 tex and individually twisted at 290 turns / meter in one direction and then collectively at 290 turns / meter in the other direction. COMPARATIVE TESTS Preservation of the expected radial dimension

[0126] The radial dimension retention of a tire 10 according to the first embodiment described above, as well as that of a bias-ply tire described previously, was tested under nominal inflation pressure. The difference between the diameter measured without pressure and the diameter measured under nominal pressure was measured. In the case of the tire 10 according to the first embodiment, a difference of 1 mm was observed, and in the case of the bias-ply tire, a difference of 1 mm was also observed. These results demonstrate what was explained previously, namely, that the radial dimension of the tire is maintained both statically and when inflation pressure is applied. Dynamic tests, i.e., with the application of rolling speed, show that the two tires exhibit a comparable difference. Speed ​​limit

[0127] The speed limit is determined by subjecting each tire to a progressive increase in speed, according to predetermined stages, until the tire is destroyed. The speed limit is the maximum speed reached before destruction. Tire 10 according to the first embodiment has a speed limit of 266 km / h, while a similar bias-ply tire of the same dimensions has a speed limit of 226 km / h, and a bias-ply tire with a belt of the same dimensions has a speed limit of 234 km / h. Mass

[0128] The mass of the tire 10 according to the first embodiment is equal to 4.85 kg while the mass of an analogous diagonal tire of the same dimensions has a mass equal to 5.30 kg and the mass of a diagonal belted tire of the same dimensions has a mass equal to 5.60 kg. Disruptive energy

[0129] The burst energy performance of tire 10, according to the first embodiment, and of a bias-ply tire of the same dimensions but without differentiation in the density of the carcass and working wire reinforcement elements was tested. The test was conducted in accordance with the recommendations of the NHTSA (National Highway Traffic Safety Administration) as indicated in the document entitled "Evaluation of Laboratory Tire Tread and Sidewall Strength (Plunger Energy) Test Method". Tire 10, according to the first embodiment, exhibited a burst energy of 44 J, and the bias-ply tire exhibited a burst energy of 45 J. In both cases, the burst energy is well above the required regulatory threshold of 34 J.

[0130] The invention, as defined in the claims, is not limited to the embodiments described above.

Claims

1. Motorcycle tyre (10) having a speed rating less than or equal to V and comprising a crown (12), first and second sidewalls (22A, 22B) and first and second beads (24A, 24B), each first and second sidewall (22A, 22B) respectively connecting each first and second bead (24A, 24B) to the crown (12), the tyre (10) comprising a carcass reinforcement (32) anchored in each first and second bead (24A, 24B) and extending radially in each first and second sidewall (22A, 22B) and axially in the crown (12), the carcass reinforcement (32) comprising a single carcass layer (34), the crown (12) comprising: - a tread (20) intended to come into contact with the ground when the tyre (10) is running, - a crown reinforcement (14) arranged radially between the tread (20) and the carcass reinforcement (32), the crown reinforcement (14) comprising a single crown layer (18), the crown layer (18) is axially delimited by first and second axial edges (18A, 18B) of the crown layer (18) and comprises filamentary crown reinforcing elements (180) extending axially from the first axial edge (18A, 18B) to the second axial edge (18A, 18B) of the crown layer (18) substantially parallel to one another in a main direction (D2) of each filamentary crown reinforcing element (180) that forms an angle AT with the circumferential direction (Z) of the tyre (10), the carcass layer (34) is axially delimited by first and second axial edges (34A, 34B) of the carcass layer (34) and comprises filamentary carcass reinforcing elements (340) extending axially from the first axial edge (34A, 34B) to the second axial edge (34A, 34B) of the carcass layer (34), each filamentary carcass reinforcing element (340) extending in a main direction (D3) of each filamentary carcass reinforcing element (340) that forms an angle ACS with the circumferential direction (Z) of the tyre (10), in a portion (34S) of the carcass layer (34) that extends axially in radial line with the crown layer (18), the angle AT and the angle ACS having opposite orientations and being such that ||AT|-|ACS|| ≤ 5°.

2. Tyre (10) according to the preceding claim, wherein the speed rating is selected from the ratings V, H, U, T, S.

3. Tyre (10) according to the preceding claim, wherein the speed rating is selected from the ratings S, R, Q, P.

4. Tyre (10) according to any one of the preceding claims, wherein each angle AT and ACS ranges, in absolute value, from 20° to 65°, preferably from 26° to 55° and more preferably still from 26° to 45°.

5. Tyre (10) according to any one of the preceding claims, wherein each first and second bead (24A, 24B) respectively comprises a first and a second circumferential reinforcing element (26), and the carcass layer (34) comprises: - an axially inner portion (34I) extending from a first point (35A) of the carcass layer (34) that is radially furthest on the inside of the first circumferential reinforcing element (26A) to a second point (35B) of the carcass layer (34) that is radially furthest on the inside of the second circumferential reinforcing element (26B), and - first and second axially outer portions (34EA, 34EB), each first and second axially outer portion (34EA, 34EB) being arranged axially on the outside of the axially inner portion (341) and extending respectively from each first and second point (35A, 35B) radially furthest on the inside of each first and second circumferential reinforcing element (26A, 26B) as far as, respectively, each first and second axial edge (34A, 34B) of the carcass layer (34), the axially inner portion (34I) and the first and second axially outer portions (34EA, 34EB) being arranged in such a way as to form first and second turn-ups around, respectively, each first and second circumferential reinforcing element (26).

6. Tyre according to the preceding claim, wherein the axially inner portion (34I) and the first and second axially outer portions (34EA, 34EB) are arranged in such a way as to form: - a first region of overlap (39A) of the carcass layer (34) comprising a part (34ITA) of the axially inner portion (34I) and the first axially outer portion (34EA) arranged axially facing one another, and - a second region of overlap (39B) of the carcass layer (34) comprising a part (34ITB) of the axially inner portion (34I) and the second axially outer portion (34EB) arranged axially facing one another, and the main direction (D3) of each filamentary carcass reinforcing element (340) forms an angle ACF1 which, in absolute value, is less than or equal to 70° with the circumferential direction (Z) of the tyre (10), in each part (34ITA, 34ITB) of the axially inner portion (34I) and each first and second axially outer portion (34EA, 34EB) of each first and second region of overlap (39A, 39B).

7. Tyre (10) according to the preceding claim, wherein the angle ACF1 is less than or equal to 65°, preferably less than or equal to 60°.

8. Tyre (10) according to Claim 6 or 7, wherein the angle ACF1 is greater than or equal to 25°, preferably greater than or equal to 30°.

9. Tyre (10) according to any one of Claims 6 to 8, wherein the axially inner portion (34I) comprises first and second interleaved portions (34GA, 34GB) interleaved respectively between: - the part (34ITA, 34ITB) of the axially inner portion (34I) of each first and second region of overlap (39A, 39B), and - the portion (34S) of the carcass layer (34) that extends axially in radial line with the crown layer (18), the main direction (D3) of each filamentary carcass reinforcing element (340) forming an angle ACF2 which, in absolute value, is greater than or equal to ACF1 and strictly greater than ACS, preferably strictly greater than ACF1 and ACS, with the circumferential direction (Z) of the tyre (10), in each first and second interleaved portion.

10. Tyre (10) according to the preceding claim, wherein the angle ACF2 is, in absolute value, less than or equal to 80°, and preferably ranges, in absolute value, from 35° to 70° and more preferably from 40° to 60°.

11. Tyre (10) according to any one of Claims 1 to 10, wherein each first and second axial edge (34A, 34B) of the carcass layer (34) is situated radially on the inside of the equator (E) of the tyre (10) and, preferably, situated radially on the inside of the equator (E) of the tyre (10) at a radial distance (C1) from the equator (E) that is greater than or equal to 50% of the radial distance (E1) between the equator (E) and the radially innermost point of the tyre (10).

12. Tyre (10) according to any one of Claims 1 to 10, wherein each first and second axial edge of the carcass layer (34) is situated radially on the outside of the equator (E) of the tyre (10) and, preferably, situated radially on the outside of the equator (E) of the tyre (10) at a radial distance (C2) from the equator (E) that is less than or equal to 50% of the radial distance (E2) between the equator (E) and the radially outermost point of the tyre (10).

13. Tyre (10) according to any one of the preceding claims, wherein the ratio of the breaking strength of the crown layer (18) to the breaking strength of the carcass layer (34) is strictly greater than 1, preferably ranges from 1.10 to 1.45 and more preferably from 1.25 to 1.35.