Tire with a tread with even wear

Abstract

The invention relates to a tire (10) comprising N1

Description

Title of the invention: Tire comprising a tread with homogeneous wear

[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 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] A passenger vehicle tire sold under the MICHELIN® brand in the PRIMACY 4® range is known from the state of the art. Such a tire comprises a tread intended to come into contact with the ground when the tire is rolling via a rolling surface.

[0003] The tread comprises main circumferential cutouts having a depth greater than or equal to 50% of the tread height and comprising first and second axially outer main circumferential cutouts arranged axially on either side of the median plane of the tire. The first and second axially outer main circumferential cutouts are the axially outermost main circumferential cutouts of the tread.

[0004] The tread comprises a first axially lateral portion arranged axially outside the first axially outer main circumferential cutout and a second axially lateral portion arranged axially outside the second axially outer main circumferential cutout. The tread also comprises transverse cutouts formed at least in part in each first and second axially lateral portion.

[0005] Despite its excellent performance, this state-of-the-art tire exhibits uneven wear. Indeed, it is observed, depending on the vehicle on which this tire is mounted, that one of the first and second axially lateral portions wears more quickly than the other. When the wear is such that the tread surface reaches the regulatory wear threshold, it is then necessary to change the tire while a significant quantity of material is still wearable on the rest of the tire.

[0006] The invention therefore aims to extend the service life of the tire by reducing the inhomogeneity of wear of the tread between the first and second axially lateral portions.

[0007] To this end, the invention relates to a tire comprising a tread intended to come into contact with the ground when the tire is rolling via a rolling surface, the tread comprising: - main circumferential cutouts having a depth greater than or equal to 50% of the tread height comprising first and second axially outer main circumferential cutouts arranged axially on either side of the median plane of the tire, the first and second axially outer main circumferential cutouts being the axially outermost main circumferential cutouts of the tread, - a first axially lateral portion arranged axially outside the first axially outer main circumferential cutout and extending axially from a first axial edge of the rolling surface to an axially outer edge of the first axially outer main circumferential cutout, - a second axially lateral portion arranged axially outside the second axially outer main circumferential cutout and extending axially from a second axial edge of the rolling surface to an axially outer edge of the second axially outer main circumferential cutout, the first axially lateral portion comprising N1 first transverse cutouts made in the first axially lateral portion, the second axially lateral portion comprising N2 second transverse cutouts made in the second axially lateral portion with N2>N1, each first and second transverse cutout, called major, extending over an axial width greater than or equal to 50% of the axial width respectively of each first and second axially lateral portion and having a depth greater than or equal to 50% of the tread height of the tire, at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts have, in at least one area, a width less than or equal to 0.50 mm.

[0008] The invention makes it possible to extend the service life of the tire by making the wear of the tread between the first and second axially lateral portions more uniform.

[0009] Indeed, the inventors behind the invention discovered that the most rigid portions of the tread are the portions that wear out the fastest, due to the fact that the engine torque passes through the most rigid portions of the tread. When there is a significant difference in rigidity between two portions of the tread, as is the case for the tire of the prior art described above, there is an inhomogeneity of wear leading to a reduced service life. The difference in rigidity is explained, in the case of the tire of the prior art, by the greater number N2 of second major transverse cutouts provided in the second axially lateral portion compared to the smaller number NI of first major transverse cutouts provided in the first axially lateral portion. Indeed, due to the relatively high number of second cutouts, the second axially lateral portion is less rigid than the first axially lateral portion.

[0010] In order to reduce or even eliminate this faster wear of the first axially lateral portion, the inventors had the idea of ​​masking the lower rigidity of the second axially lateral portion by blocking the relative movements of the loaves separated by the second major transverse cutouts by creating at least one zone (the one where the width is less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm) between the leading and trailing faces of a significant number (at least 50% in number) of second major transverse cutouts when the tire is in operation. Indeed, thanks to this zone, it is easier to immobilize the loaves carrying the leading and trailing faces when the tire is in operation, which has the effect of making this second axially lateral portion more rigid. In the same way, the loaves separated by the first major transverse cutouts are also blocked.Thus, regardless of the number of cutouts present on the first and second axially lateral portions, each of these first and second axially lateral portions is stiffened in a comparable manner so that the wear between the first and second axially lateral portions is homogenized.

[0011] The value of 0.50 mm was determined by the inventors as the value below which contact between the leading and trailing faces was observed in the vast majority of observed driving conditions (load, speed, inflation pressure, etc.). Above this value of 0.50 mm, the leading and trailing faces may come into contact with each other but under extreme driving conditions not reflecting normal use of the tire.

[0012] The area in which the width is less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm may be reduced to two points on the leading and trailing faces distant from each other by a distance less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm or extend over surfaces not reduced to two points on the leading and trailing faces. In this case of surfaces not reduced to two points on the leading and trailing faces, a plurality of points on each leading and trailing face are distant two by two by a distance in less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm.

[0013] The characteristic according to which N2 / N1>1 makes it possible in particular to reduce the noise generated by the tire. Indeed, each axial portion of the tread generates a noise whose harmonic is centered on a frequency which depends in particular on the number and distribution of the transverse cutouts made in this axial portion of the tread. In order to reduce the noise generated by the tire, the inventors discovered that it was effective to spread the frequencies of the harmonics of the different axial portions of the tread and therefore to spread the acoustic energy generated by the tire.In order to spread these frequencies, the tire according to the invention is such that the first and second axially lateral portions have different numbers of major transverse cutouts making it possible to differentiate the harmonics associated with each first and second axially lateral portion and therefore to reduce the noise generated by the tire.

[0014] Conventionally, the tread surface is delimited axially by 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 and inflated to the nominal pressure within the meaning of the European Tire and Rim Technical Organization or "ETRTO" standard, 2021. 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 rolling surface is continuous with the external surfaces of the sidewalls of the tire, it will be possible, for example, to determine the first and second axial edges by considering that each first and second axial edge passes, in each meridian section plane, through the point for which the angle between the tangent to the rolling surface and a straight line parallel to the axial direction passing through this point is equal to 30°. When there are several points on a meridian section plane for which said angle is equal in absolute value to 30°, the radially outermost point is retained.

[0015] The or each first and second axially lateral portion of the tread may of course comprise other transverse cutouts other than the first and second major transverse cutouts. The or each first and second axially lateral portion of the tread may also comprise other cutouts than the major transverse cutouts or not, for example circumferential cutouts.

[0016] A cutout or a portion of a cutout has, on the rolling surface, two main characteristic dimensions: a width and a curvilinear length such that the curvilinear length is at least equal to twice the width. A cutout is therefore delimited by at least two main lateral faces determining its curvilinear length and connected by a bottom, the two main lateral faces being distant from each other by a non-zero distance, called the width of the cutout.

[0017] The width of a cutout is, on a new tire, the maximum distance between the two main lateral faces measured, by default and in the case where the cutout does not include a chamfer, at a radial dimension coincident with the rolling surface, and by default and in the case where the cutout includes a chamfer, at the radial dimension most radially outer of the cutout and radially inner of the chamfer. The width is measured substantially perpendicular to the main lateral faces. If a width other than the default width is specified, for example a width at a particular dimension, the width is equal to the smallest distance between the two main lateral faces at the particular dimension of the cutout.

[0018] The depth of a cut is, on a new tire, the maximum radial distance between the bottom of the cut and its projection onto the ground when the tire is rolling. The maximum value of the depths of the cuts is called the tread height.

[0019] A cutout can be transverse or circumferential.

[0020] A transverse cutout is such that the cutout extends in a mean direction forming an angle strictly greater than 30°, preferably greater than or equal to 45° with the circumferential direction of the tire, i.e. forming an angle less than or equal to 60°, preferably strictly less than 45° with the axial direction of the tire. The mean direction is the shortest curve joining the two ends of the cutout and parallel to the rolling surface. A transverse cutout may be continuous, i.e. not be interrupted by a tread block or another cutout so that the two main lateral faces determining its length are uninterrupted over the length of the transverse cutout.A transverse cutout may also be discontinuous, that is to say interrupted by one or more sculpture blocks and / or one or more cutouts so that the two main lateral faces determining its length are interrupted by one or more sculpture blocks and / or one or more cutouts.

[0021] A circumferential cutout is such that the cutout extends in a mean direction forming an angle less than or equal to 30°, preferably less than or equal to 10° with the circumferential direction of the tire, i.e. forming an angle strictly greater than 60°, preferably strictly greater than 80° with the axial direction of the tire. The mean direction is the shortest curve joining the two ends of the cutout and parallel to the running surface. In the case of a continuous circumferential cutout, the two ends coincide with each other and are joined by a curve making a complete turn of the tire. A circumferential cutout may be continuous, i.e. not interrupted by a tread block or another cutout so that the two main lateral faces determining its length are uninterrupted over the entire turn of the tire. A circumferential cutout may also be discontinuous, i.e. interrupted by one or more tread blocks and / or one or more cutouts so that the two main lateral faces determining its length are interrupted by one or more tread blocks and / or one or more cutouts over the entire turn of the tire.

[0022] In the case of a transverse cut, the lateral faces are called the leading face and the trailing face and each is provided respectively with a leading edge and a trailing edge, the leading edge being the edge which, for a given circumferential line, enters the contact area before the trailing edge.

[0023] In embodiments for optionally improving braking on dry ground, the or each transverse cutout is provided with chamfers. A chamfer of a transverse cutout may be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a flat face inclined relative to the leading or trailing face which it extends to the leading or trailing edge circumferentially delimiting the transverse cutout. A rounded chamfer is formed by a curved face connecting tangentially to the leading or trailing face which it extends. A chamfer of a transverse cutout is characterized by a height and a width equal respectively to the radial distance and to the distance in a direction perpendicular to the leading or trailing faces between the common point between the leading or trailing face extended by the chamfer and the leading or trailing edge circumferentially delimiting the transverse cutout. 。

[0024] In certain embodiments for optionally improving wet braking and also dry transverse grip, at least one of the main circumferential cutouts is provided with chamfers. A chamfer of a circumferential cutout may be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a flat face inclined relative to the axially inner and outer face which it extends to the axially inner or outer edge axially delimiting the circumferential cutout. A rounded chamfer is formed by a curved face connecting tangentially to the axially inner or outer face which it extends. A chamfer of a circumferential cutout is characterized by a height and a width equal respectively to the radial distance and the axial distance between the common point between the axially inner or outer face outer edge extended by the chamfer and the axially inner or outer edge axially delimiting the circumferential cutout.

[0025] 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.

[0026] By axial direction is meant the direction substantially parallel to the axis of revolution of the tire, i.e. the axis of rotation of the tire.

[0027] By circumferential direction is meant the direction which is, in each meridian plane, substantially perpendicular both to 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).

[0028] By radial direction is meant 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.

[0029] 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 beads and passes through the axial center of the crown reinforcement.

[0030] By equatorial circumferential plane of the tire is meant, in a meridian section plane, the plane passing through the equator of the tire, perpendicular to the median plane and to the radial direction. The equator of the tire is, in a meridian section plane (plane perpendicular to the circumferential direction and parallel to the radial and axial directions) the axis parallel to the axis of rotation of the tire and located equidistant between the radially outermost point of the tread intended to be in contact with the ground and the radially innermost point of the tire intended to be in contact with a support, for example a rim.

[0031] By meridian plane is meant a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0032] By radially inner, respectively radially outer, is meant closer to the axis of rotation of the tire, respectively further from the axis of rotation of the tire. By axially inner, respectively axially outer, is meant closer to the median plane of the tire, respectively further from the median plane of the tire.

[0033] 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.

[0034] Any interval 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., excluding the limits a and b), 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 limits a and b).

[0035] The tires are, in preferred embodiments of the invention, intended for passenger vehicles as defined within the meaning of the standard of the European Tyre and Rim Technical Organization or "ETRTO", 2021. Such a tire has a section in a meridian section plane characterized by a section height H and a nominal section width or bead thickness S within the meaning of the standard of the European Tyre and Rim Technical Organization or "ETRTO", 2021 such that the ratio H / S, expressed as a percentage, is at most equal to 90, preferably at most equal to 70 and is at least equal to 30, and the nominal section width S is at least equal to 115 mm, preferably at least equal to 175 mm and at most equal to 385 mm, preferably at most equal to 315 mm. In addition, the diameter at hook D, defining the diameter of the tire mounting rim, is at least 12 inches, preferably at least 16 inches and at most 24 inches.

[0036] The tires are, in preferred embodiments of the invention, so-called summer tires. By summer, we mean tires which are not so-called 4-season or all-season tires, nor so-called winter tires.

[0037] Winter tires are notably identified by an M+S marking (M+S being the acronym for “Mud + Snow”) and / or 3PMSF (3PMSF being the acronym for “3 Peak Mountain Snow Flake”). 4-season or all-season tires, due to their performance on snow, also have the M+S and / or 3PMSF markings. Thus, a summer tire does not have an M+S marking or a 3PMSF marking.

[0038] In embodiments making it possible to further homogenize the wear between the first and second axially lateral portions, at least 75% of the first major transverse cutouts and at least 75% of the second major transverse cutouts, preferably, each first major transverse cutout and each second major transverse cutout has, in at least one zone, a width less than or equal to 0.35 mm.

[0039] Optionally and preferably, at least 50% of the first major transverse cutouts and at least 50% of the second major transverse cutouts have, in at least one zone, a width less than or equal to 0.40 mm, and more preferably less than or equal to 0.35 mm. By reducing the width of the zone, it is further facilitated to bring the leading and trailing faces into contact.

[0040] Optionally and preferably, at least 75% of the first major transverse cutouts and at least 75% of the second major transverse cutouts, preferably each first major transverse cutout and each second major transverse cutout present, in at least one zone, a width less than or equal to 0.40 mm and more preferably less than or equal to 0.35 mm.

[0041] Optionally and preferably, the zone extends over at least 10% of the height and at least 10% of the length of at least 50% of the first major transverse cutouts and at least 50% of the second major transverse cutouts. By increasing the height and the length over which the loaves are likely to come into contact with each other, it is further facilitated to bring the leading and trailing faces into contact.

[0042] Optionally and preferably, the zone extends over a continuous surface representing at least 10%, preferably at least 20% of the surface of each leading and trailing face of the at least 50% of the first major transverse cutouts and at least 50% of the second major transverse cutouts. Thus, thanks to a continuous surface, the contacting capacity of the leading and trailing faces is maximized with respect to specific contacting points.

[0043] Advantageously, the zone extends over a continuous surface representing at most 80%, preferably at most 50% of the surface of each leading and trailing face of at least 50% of the first major transverse cutouts and at least 50% of the second major transverse cutouts.

[0044] Even more preferably, the zone extends over a continuous surface representing at least 10%, preferably at least 20% and at most 80%, preferably at most 50% of the surface of each leading and trailing face of at least 75% and very preferably of each of the first major transverse cutouts and at least 75% and very preferably of each of the second major transverse cutouts.

[0045] In preferred and optional embodiments, each first and second major transverse cutout has a radially middle portion, a radially outer portion arranged radially outside the radially middle portion and a radially inner portion arranged radially inside the radially middle portion, the radially middle portion extending radially over a height equal to 50% of the height of said first and second major transverse cutout, each radially inner and outer portion extending radially over a height equal to 25% of the height of said first and second major transverse cutout, the area of ​​at least 50% of the first major transverse cutouts and at least 50% of the second major transverse cutouts,preferably at least 75% of the first major transverse cutouts and at least 75% of the second major transverse cutouts and more preferably each of the first and second major transverse cutouts is located at least partly in the middle portion.

[0046] Thus, it is ensured that the contact between the leading face and the trailing face is made in the middle portion. This allows the first and second major cutouts to have a relatively large width in the other portions, in particular in the radially outer portion, which makes it possible to increase the surface notching rate.

[0047] In certain embodiments, at least 50% of the first major transverse cutouts and at least 50% of the second major transverse cutouts, preferably at least 75% of the first major transverse cutouts and at least 75% of the second major transverse cutouts and more preferably each of the first and second major transverse cutouts has a radially inner portion and a radially outer portion arranged radially outside the radially inner portion, the radially inner portion being the radially innermost portion of said first and second major transverse cutout and the radially outer portion being the radially outermost portion of said first and second major transverse cutout,the radially inner portion having a maximum width strictly greater than the maximum width of the radially outer portion. By using major transverse cutouts having a radially variable maximum width, the occurrence of tearing of the breads is minimized, in particular in the second axially lateral portion.

[0048] In advantageous but optional embodiments, the tire has an inner side and an outer side imposed when the tire is mounted on a vehicle, the first axially lateral portion is arranged on the same side of the median plane as the outer side and the second axially lateral portion is arranged on the same side of the median plane as the inner side.

[0049] By inner and outer sides imposed when the tire is mounted on the vehicle, it is meant 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 operation. Indeed, mounting a tire with an orientation different from that imposed by the manufacturer can lead to dangerous 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.

[0050] In advantageous but optional embodiments, each first and second major transverse cutout extends axially from respectively each first and second axial edge of the rolling surface until it opens respectively into each first and second axially outer main circumferential cutout. This promotes the mobility of the blocks of the first and second axially lateral portions, which improves the flattening of the tire and consequently the rolling resistance.

[0051] In other embodiments, it may be envisaged that each first major transverse cutout and / or each second major transverse cutout is non-opening respectively into each first and second axially external main circumferential cutout which is adjacent to it. In these variants, we will speak of blind major transverse cutouts.

[0052] In advantageous embodiments, N2 / Nl>1.30 and preferably N2 / Nl>1.50. By further differentiating the number of first and second major transverse cutouts provided respectively in each first and second axially lateral portion, the noise generated by the tire is further reduced.

[0053] Advantageously, N2 / N1<2.00, preferably N2 / N1<1.75. By differentiating too much the number of first and second major transverse cutouts provided respectively in each first and second axially lateral portion, a relatively significant difference would be created between the rigidities of the first and second axially lateral portions, which would increase the risk of inhomogeneous wear.

[0054] In preferred variants, the C / N2 ratio ranges from 14 to 20, preferably from 16 to 19. In other preferred variants compatible with the previous preferred variants, the ratio C / Nl ranges from 24 to 30, preferably from 27 to 29. In these ratios, C is the value of the circumference of the unmounted, uninflated tire expressed in millimeters.

[0055] According to the invention, the tire comprises k>l central rib(s) i delimited axially by first and second axially adjacent main circumferential cutouts, the or each central rib i comprising Mi>l transverse cutouts formed in said central rib i, each transverse cutout formed in said central rib i, called major, extending over an axial width greater than or equal to 50% of the axial width of said central rib i and having a depth greater than or equal to 50% of the tread height of the tire.

[0056] In advantageous but optional embodiments, each major transverse cutout provided in each central rib i extends axially from each first main circumferential cutout until it opens into each second main circumferential cutout. Thus, the mobility of the blocks of each central rib is promoted, which improves the flattening of the tire and therefore, rolling resistance.

[0057] According to the invention, there is at least one central rib j comprising Mj>l major transverse cutouts made in said central rib] such that Nl <Mj<N2. La nervure centrale] dans laquelle sont ménagées les Mj découpures transversales majeures permet d’étaler encore davantage l’énergie acoustique générée par le pneumatique et donc de réduire le bruit généré par le pneumatique.

[0058] In advantageous and optional variants, N2 / Mj > 1.15 and Mj / Nl>1.15 and preferably N2 / Mj > 1.25 and Mj / Nl>1.25. By further differentiating the number of Mj major transverse cutouts relative to the numbers of first and second major transverse cutouts provided respectively in each first and second axially lateral portion, the noise generated by the tire is further reduced.

[0059] Advantageously, N2 / Mj <l,75 et Mj / Nl<l,75, de préférence N2 / Mj<l,50 et Mj / NI <1,50. En différenciant trop le nombre des découpures transversales majeures ménagées dans la nervure centrale j dans laquelle sont ménagées les Mj découpures transversales majeures, on créerait une différence relativement importante entre les rigidités des première et deuxième portions axialement latérales, d’une part et, la nervure centrale j dans laquelle sont ménagées les Mj découpures transversales majeures d’autre part ce qui augmenterait le risque d’usure inhomogène.

[0060] In preferred variants, the C / Mj ratio ranges from 18 to 23, preferably from 20 to 23. As previously, C is the value of the circumference of the unmounted and uninflated tire, expressed in millimeters.

[0061] In preferred and optional embodiments, NI, N2 and Mj are such that: - 0.40 < [(Nl / Rl) - (Mj x Rj)] / [(Mj / Rj) - (NI x RI)] < 0.60, - 0.40 < [(Mj / Rj) - (N2 x R2)] / [(N2 / R2) - (Mj x Rj)] < 0.60, and with: - RI being the pitch ratio equal to the ratio between the minimum distance between two first circumferentially consecutive major transverse cutouts and the maximum distance between two first circumferentially consecutive major transverse cutouts, - R2 being the pitch ratio equal to the ratio between the minimum distance between two second circumferentially consecutive major transverse cutouts and the maximum distance between two second circumferentially consecutive major transverse cutouts, - Rj being the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive major transverse cutouts of the or each central rib j and the maximum distance between two circumferentially consecutive major transverse cutouts of said or each central rib j.

[0062] In these preferred embodiments, acoustic overlap rates are determined between, on the one hand, the first axially outer portion and the or each central rib j and, on the other hand, the second axially outer portion and the or each central rib j. The lower these overlap rates are, the more the acoustic energy is spread out, which makes it possible to reduce the noise generated by the tire. However, it is preferable not to have overlap rates that are too small because this increases the risk of generating a frequency modulation resulting in a flapping noise.

[0063] In preferred and optional embodiments, NI, N2 and Mj are such that 0.50 < [Min(Nl x RI; N2 x R2; Mj x Rj) / Max(Nl / Rl; N2 / R2; Mj / Rj)]A(0.5) < 0.60, with: - RI being the pitch ratio equal to the ratio between the minimum distance between two first circumferentially consecutive major transverse cutouts and the maximum distance between two first circumferentially consecutive major transverse cutouts, - R2 being the pitch ratio equal to the ratio between the minimum distance between two second circumferentially consecutive major transverse cutouts and the maximum distance between two second circumferentially consecutive major transverse cutouts, - Rj being the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive major transverse cutouts of the or each central rib j and the maximum distance between two circumferentially consecutive major transverse cutouts of said or each central rib j, - Min(Nl x RI; N2 x R2; Mj x Rj) being the minimum value of the product between the number of major transverse cutouts and the pitch ratio of the first and second axially outer portions and of the or each central rib j, - Max(Nl / Rl; N2 / R2; Mj / Rj) being the maximum value of the ratio between the number of major transverse cutouts and the pitch ratio of the first and second axially outer portions and of the or each central rib j.

[0064] In these preferred embodiments, the overall pitch ratio is determined between the first axially outer portion, the or each central rib and the second axially outer portion. The lower this overall pitch ratio, the more the acoustic energy is spread out, which makes it possible to reduce the noise generated by the tire. However, it is preferable not to have an overall pitch ratio that is too small because this would generate excessively large differences in stiffness and increase the risk of localized wear.

[0065] In preferred and optional embodiments, at least 50%, preferably at least 75% and more preferably each of the major transverse cutouts made in the or each central rib i have, in at least one zone, a width less than or equal to 0.50 mm. In order to mask any differences in rigidity between the or each central rib i and the first and second axially lateral portions, the or each central rib i is stiffened in a comparable manner so that the wear between the or each central rib i and the first and second axially lateral portions is homogenized.

[0066] Preferably, at least 50%, preferably at least 75% and more preferably each of the major transverse cutouts made in the or each central rib i have, in at least one zone, a width less than or equal to 0.40 mm and more preferably less than or equal to 0.35 mm.

[0067] In preferred variants, the zone extends over at least 10% of the height and over at least 10% of the length of at least 50%, preferably at least 75% and more preferably of each of the major transverse cutouts made in the or each central rib i. By increasing the height and the length over which the loaves are likely to come into contact with each other, it is further facilitated to bring the leading and trailing faces into contact.

[0068] Optionally and preferably, the zone extends over a continuous surface representing at least 10%, preferably at least 20% of the surface of each leading and trailing face of the at least 50% of the major transverse cutouts made in the or each central rib i. Thus, thanks to a continuous surface, the contacting capacity of the leading and trailing faces is maximized with respect to specific contact points.

[0069] Advantageously, the zone extends over a continuous surface representing at most 80%, preferably at most 50% of the surface of each leading and trailing face of the at least 50% of the major transverse cutouts made in the or each central rib i.

[0070] Even more preferably, the zone extends over a continuous surface representing at least 10%, preferably at least 20% and at most 80%, preferably at most 50% of the surface of each leading and trailing face of at least 75% and very preferably of each of the major transverse cutouts made in the or each central rib i.

[0071] In preferred and optional embodiments, each major transverse cutout provided in the or each central rib i has a radially median portion, a radially outer portion arranged radially outside the radially median portion and a radially inner portion arranged radially inside the radially median portion, the radially median portion extending radially over a height equal to 50% of the height of said major transverse cutout, each radially inner and outer portion extending radially over a height equal to 25% of the height of said major transverse cutout, the area of ​​at least 50% of the major transverse cutouts provided in the or each central rib i, preferably at least 75% of the major transverse cutouts provided in the or each central rib i and more preferably of each major transverse cutout provided in the or each central rib i is located at least partly in the middle portion.

[0072] In a similar manner to the first and second major transverse cutouts, it is ensured that the contact between the leading face and the trailing face is made in the middle portion. This allows the major transverse cutouts to have a relatively large width in the other portions, in particular in the radially outer portion, which makes it possible to increase the surface notching rate.

[0073] In certain preferred variants, there is at least one central rib i comprising the same number of major transverse cutouts as the first axially lateral portion and / or there is at least one central rib i comprising the same number of major transverse cutouts as the second axially lateral portion. These variants make it possible to create visual continuity between the first and second axially lateral portions and some of the central ribs. Even more preferably, the or one of the ribs comprising the same number of major transverse cutouts as the first axially lateral portion is the rib axially adjacent to the first axially lateral portion and / or the or one of the ribs comprising the same number of major transverse cutouts as the second axially lateral portion is the rib axially adjacent to the second axially lateral portion.

[0074] In embodiments making it possible to further reduce the noise generated by the tire, each major transverse cutout is formed in the or each central rib i until it opens into each of the first and second circumferential cutouts axially delimiting said central rib i into first and second opening zones respectively, the azimuth of a point in the first opening zone of a first major transverse cutout formed in said central rib i is substantially circumferentially aligned with the azimuth of a point in the second opening zone of a second major transverse cutout formed in said central rib i, the first and second major transverse cutouts formed in said central rib i being circumferentially adjacent.

[0075] By substantially aligned, it is meant that the azimuths are circumferentially distant from each other by at most 5% of the average distance separating the first and second circumferentially adjacent major transverse cutouts made in said central rib i.

[0076] Preferably, each main circumferential cutout has a depth greater than or equal to 75% and more preferably 90% of the sculpture height.

[0077] In embodiments in which the main circumferential cutouts are relatively deep and suitable for passenger vehicle or light truck tires, each main circumferential cutout has a depth ranging from 4.0 mm at the tread height, preferably from 5.0 mm at the tread height, and more preferably from 5.5 mm at the tread height.

[0078] In embodiments in which the main circumferential cutouts are relatively wide main circumferential grooves suitable for passenger vehicle or light truck tires, each main circumferential cutout has an axial width greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm and more preferably ranging from 5.0 mm to 13.0 mm.

[0079] Conventionally, the tire comprises a crown, two sidewalls, two beads, each sidewall connecting each bead to the crown. Still conventionally, the crown comprises the tread and a crown reinforcement arranged radially inside the tread. The tire also comprises a carcass reinforcement anchored in each bead and extending radially in each sidewall and axially in the crown radially inside the crown reinforcement.

[0080] Conventionally, the crown reinforcement comprises at least one crown layer comprising reinforcing elements. These reinforcing elements are preferably textile or metal wire elements.

[0081] In embodiments allowing the performance of so-called radial tires to be obtained, for example as defined by the ETRTO, the carcass reinforcement comprises at least one carcass layer, the or each carcass layer comprising carcass filamentary reinforcement elements, each carcass filamentary reinforcement element extending substantially in a main direction forming with the circumferential direction of the tire, an angle, in absolute value, ranging from 80° to 90°.

[0082] 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: - [Fig.l] is a top view of the tread of a tire according to the invention, - [Fig.2] is a sectional view of a major transverse cut in the plane II-II' beyond [Fig.l], - [Fig.3] is a sectional view of a major transverse cut in plane III-III' of [Fig.l], and - [Fig.4] is a view similar to that of [Fig.l] of a control tire making it possible to demonstrate the interest of the invention.

[0083] A reference X, Y, Z is shown corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions of a tire.

[0084] With reference to [Fig.l], the tire according to the invention is 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 R19. The tire 10 is a summer tire. The tire 10 is shown in new condition, that is to say not yet having been driven.

[0085] The tire 10 comprises a tread 14 intended to come into contact with a ground when rolling. The tire 10 further comprises a conventional structure, such as for example described in applications WO2021250331, WO2022074341 or WO2022069819.

[0086] The tire 10 is obtained by molding a raw blank in a mold comprising a plurality of different patterns. In [Fig.l], the junctions J between two circumferentially adjacent patterns are represented by continuous lines. In this case, the mold comprises three different patterns which have been distributed randomly so as to mold the tread 14.

[0087] The tread 14 comprises a tread surface 38 via which the tread 14 is intended to come into contact with the ground when the tire 10 is rolling on the ground. The tread surface 38 is delimited axially by first and second axial edges 41, 42. The tire 10 has an inner side INT and an outer side EXT imposed when the tire 10 is mounted on a vehicle.

[0088] The tread 14 comprises an axially central portion PO and first and second axially lateral portions PI, P2 arranged axially outside the axially central portion PO on either side axially of the axially central portion PO relative to the median plane M of the tire 10. The first axially lateral portion PI is arranged on the same side of the median plane as the outer side EXT and the second axially lateral portion P2 is arranged on the same side of the median plane as the inner side INT.

[0089] The tread 14 comprises N>1 main circumferential cutouts, here N=6 main circumferential grooves designated by the references 51, 52, 53, 54, 55, 56. The axially external main circumferential cutouts 51, 52, called first and second axially outer main circumferential cutouts 51, 52, are arranged axially on either side of the median plane M of the tire 10 and are the axially outermost main circumferential cutouts of the tread 14.

[0090] The first axially lateral portion PI and the second axially lateral portion P2 are arranged respectively axially outside the first axially outer main circumferential cutout 51 and the second axially outer main circumferential cutout 52. The first axially lateral portion PI extends axially from the first axial edge 41 of the rolling surface 38 to the axially outer edge 43 of the first axially outer main circumferential cutout 51. The second axially lateral portion P2 extends axially from the second axial edge 42 of the rolling surface 38 to the axially outer edge 44 of the second axially outer main circumferential cutout 52.

[0091] Each main circumferential cutout 51 to 56 has a depth ranging from 4.0 mm to the tread height Hs, preferably ranging from 5.0 mm to the tread height Hs and more preferably ranging from 5.5 mm to the tread height Hs. Each depth is greater than or equal to 50%, preferably 75% and more preferably 90% of the tread height. Here, Hs=6.3 mm, the depth of each first and second axially outer main circumferential cutout 51, 52 is equal to 5.8 mm, the depth of each main circumferential cutout 53, 56 is equal to 6.1 mm and the depth of each main circumferential cutout 54, 55 is equal to 6.3 mm.

[0092] Each main circumferential cutout 51 to 56 respectively has an axial width greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm and more preferably ranging from 5.0 mm to 13.0 mm. Here, the width of each first and second axially outer main circumferential cutout 51, 52 and each main circumferential cutout 53, 56 is equal to 8.4 mm, the width of the main circumferential cutout 54 is equal to 9.0 mm and the width of the main circumferential cutout 55 is equal to 9.5 mm.

[0093] The axially central portion PO comprises k>1 central ribs, here k=5 central ribs 61, 62, 63, 64, 65. Each central rib 61 to 65 is arranged axially between first and second axially adjacent main circumferential cutouts among the main circumferential cutouts 51 to 56 and here delimited axially by said first and second axially adjacent main circumferential cutouts among the main circumferential cutouts 51 to 56.

[0094] The first axially lateral portion PI comprises NI first transverse cutouts 81 formed in the first axially lateral portion PL La second axially lateral portion P2 comprises N2 second transverse cutouts 82 formed in the second axially lateral portion P2.

[0095] Each central rib 61, 62, 63, 64 and 65 comprises respectively M61, M62, M63, M64 and M65 transverse cutouts made in said central rib 61, 62, 63, 64 and 65 and respectively designated by the references 71, 72, 73, 74 and 75.

[0096] Each transverse cutout 81, 82 extends over an axial width greater than or equal to 50% of the axial width respectively of each first and second axially lateral portion PI, P2, here over an axial width equal to greater than the axial width of each first and second axially lateral portion PI, P2. Thus, each first and second transverse cutout 81, 82 extends axially from respectively each first and second axial edge 41, 42 until it opens respectively into each first and second axially outer main circumferential cutout 51, 52. Each transverse cutout 81, 82 has a depth greater than or equal to 50% of the tread height Hs of the tire 10, here a depth equal to 5.3 mm.

[0097] Each transverse cutout 71, 72, 73, 74 and 75 extends over an axial width greater than or equal to 50% of the axial width of each central rib 61, 62, 63, 64 and 65 respectively, here over an axial width equal to 100% of the axial width of each central rib 61, 62, 63, 64 and 65. Thus, each transverse cutout 71, 72, 73, 74 and 75 extends axially from each first main circumferential cutout respectively 51, 53, 54, 55, 56 until it opens into each second main circumferential cutout respectively 53, 54, 55, 56, 52. Each transverse cutout 71, 72, 73, 74 and 75 has a depth greater than or equal to 50% of the tread height Hs of the tire 10, here a depth equal to 6.0 mm for each cutout 71, 75, a depth equal to 6.2 mm for each cutout 72, 74 and a depth equal to 6.3 mm for each cutout 73.

[0098] Due to the proportion of the axial width of the axially lateral portion or central rib over which they extend and their depth relative to the tread height, the transverse cutouts 81, 82, 71, 72, 73, 74 and 75 are referred to as major transverse cutouts.

[0099] There is at least one central rib among the central ribs 61 to 65 having the same number of major transverse cutouts as the first axially lateral portion PI. Here, the central rib 61 axially adjacent to the first axially lateral portion PI and the central rib 62 are such that M61=M62=N1=83. There is also at least one central rib among the central ribs 61 to 65 having the same number of major transverse cutouts as the second axially lateral portion P2. Here, the central rib 65 axially adjacent to the second axially lateral portion P2 is such that M65=N2=134. Note that NI and N2 verify N2 / N1 > 1.30, preferably N2 / N1 > 1.50 and N2 / N1<2.00, preferably N2 / N1<1.75 and here N2 / N1=1.61.

[0100] There is at least one central rib j among the central ribs 61 to 65 comprising Mj major transverse cutouts such as Nl <Mj<N2. Ici les nervures centrales 63, 64 sont telles que M63=M64=106. On notera que NI, N2, M63 et M64 vérifient N2 / M63=N2 / M64 > 1.15 and M63 / N1=M64 / N1 > 1.15 and preferably N2 / M63= N2 / M64 > 1.25 and M63 / N1=M64 / N1>1.25. It should also be noted that N2 / M63= N2 / M64<1.75 and M63 / N1=M64 / N1<1.75, preferably N2 / M63=N2 / M64 <l,50 et m63 n1="M64 / N1<1,5O."

[0101] RI can be defined as the pitch ratio equal to the ratio between the minimum distance between two first circumferentially consecutive major transverse cutouts 81, here equal to 23.7 mm and the maximum distance between two first circumferentially consecutive major transverse cutouts 81, here equal to 33.9 mm. R2 can also be defined as the pitch ratio equal to the ratio between the minimum distance between two second circumferentially consecutive major transverse cutouts 82, here equal to 14.6 mm and the maximum distance between two second circumferentially consecutive major transverse cutouts 82, here equal to 20.9.Finally, R63 and R64 can be defined as the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive major transverse cutouts 73, 74 of each central rib 63, 64, here equal to 18.5 mm and the maximum distance between two circumferentially consecutive major transverse cutouts 73, 74 of each central rib 63, 64, here equal to 20.9 mm. Here, R1=R2=R63=R64=0.70.

[0102] This makes it possible to define overlap rates T1,63=T1,64=[(N1 / R1) - (M63 x R63)] / [(M63 / R63) - (NI x Rl)]= [(Nl / Rl) - (M64 x R64)] / [(M64 / R64) - (NI x RI)] between the first axially lateral portion PI and each central rib 63, 64. This also makes it possible to define overlap rates T63,2=T64,2=[(M63 / R63) - (N2 x R2)] / [(N2 / R2) - (M63 x R63)]=[(M64 / R64) - (N2 x R2)] / [(N2 / R2) - (M64 x R64)] between the second axially lateral portion P2 and each central rib 63, 64.

[0103] This also makes it possible to define an overall pitch ratio Rpg=[Min(Nl x RI; N2 x R2; M63 x R63; M64 x R64) / Max(Nl / Rl; N2 / R2; M63 / R63; M64 / R64)]A(0.5) in which Min(Nl x RI; N2 x R2; M63 x R63; M64 x R64) is the minimum value of the product between the number of major transverse cutouts and the pitch ratio of the first and second axially outer portions PI, P2 and of each central rib 63, 64, here the product between the number NI of major transverse cutouts 81 of the first axially outer portion PI and the pitch ratio RI and in which Max(Nl / Rl; N2 / R2; M63 / R63; M64 / R64) being the maximum value of the ratio between the number of major transverse cutouts and the pitch ratio of the first and second axially outer portions PI, P2 and of each central rib 63, 64, here the ratio between the number N2 of major transverse cutouts 82 of the second axially outer portion P2 and the pitch ratio R2.

[0104] Tl,63, Tl,64, T63,2 and T64,2 verify on the one hand, 0.40 < T1,63=T1,64 < 0.60 and, on the other hand, 0.40 < T63,2=T64,2 < 0.60 and finally 0.50 < Rpg < 0.60. Here, Tl,63=Tl,64=0.48, T63,2=T64,2=0.49 and Rpg=0.55.

[0105] The tire 10 has a diameter equal to 741 mm and a circumference C equal to 2326.8 mm so that on the one hand, the ratio C / N1 ranges from 24 to 30, preferably from 27 to 29 and here C / N1=28, on the other hand, the ratio C / N2 ranges from 14 to 20, preferably from 16 to 19 and here C / N2=17 and finally the ratio C / M63=C / M64 ranges from 18 to 23, preferably from 20 to 23 and here C / M63=C / M64=22.

[0106] Each major transverse cutout 71, 72, 73, 74 and 75 formed respectively in each central rib 61, 62, 63, 64 and 65 opens into each of the first and second circumferential cutouts axially delimiting said central rib 61, 62, 63, 64 and 65 in respectively first and second opening zones 711, 712, 721, 722, 731, 732, 741, 742, 751, 752.

[0107] Considering as an illustrative example the first and second major transverse cutouts 75A, 75B formed in the central rib 65 and circumferentially adjacent, the azimuth AZ1 of a point of the first outlet zone 751 of the first major transverse cutout 75A is substantially circumferentially aligned with the azimuth AZ2 of a point of the second outlet zone 752 of the second major transverse cutout 75B. This circumferential alignment characteristic is also reproduced by the cutouts 71, 72, 73 and 74 formed respectively in each central rib 61, 62, 63 and 64.

[0108] The major transverse cutouts 81, 82 and 71 to 75 as well as the main circumferential cutouts 51 to 56 delimit a plurality of loaves bearing chamfers on each of their circumferential edges and each of their transverse edges.

[0109] Figures 2 and 3 show respectively a first major transverse cutout 81 and a major transverse cutout 75. The first major transverse cutouts 81 are all identical to each other and, to within a homothetic factor, are identical to the second major transverse cutouts 82. The major transverse cutouts 75 are, to within a homothetic factor, identical to the major transverse cutouts 71, 72, 73 and 74.

[0110] With reference to [Fig.2], at least 50%, preferably at least 75% of the first major transverse cutouts 81 and here each first major transverse cutout 81 has a radially inner portion 8 li, a radially middle portion 81m and a radially outer portion 81e. The radially in inner portion 81i is arranged radially inside the radially middle portion 81m. The radially outer portion 81e is arranged radially outside the radially middle portion 81m. The radially inner portion 81i is the radially innermost portion of the first major transverse cutout 81 and the radially outer portion 81e is the radially outermost portion of the first major transverse cutout 81. The radially middle portion 81m extends radially over a height H2 equal to 50% of the height H81 of the first major transverse cutout 81. Each radially inner portion 81i and outer portion 81e extends radially respectively over a height H1, H3 equal to 25% of the height H81 of the first major transverse cutout 81.

[0111] The radially inner portion 811 has a maximum width Lmax1 strictly greater than the maximum width of the radially outer portion Lmax3. In the section plane II-II', each first major transverse cutout 81 has a minimum width Lmin81 here equal to 0.30 mm. This is also true for the second major transverse cutouts 82. Here Lmax1=1.16 mm and Lmax3=1.00 mm.

[0112] At least 50%, preferably at least 75% of the first major transverse cutouts 81 and here each first major transverse cutout 81 has, in at least one zone 90, a width less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm. In the example shown in [Fig.2], the width of at least 50%, preferably 75% and here of each of the first major transverse cutouts 81 is less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm over at least 10% of its height H81, here represented by the portion of height H4, and over at least 10% of its length. The zone 90 of at least 50%, preferably at least 75% of the first major transverse cutouts 81 and here of each first major transverse cutout 81 is located at least in part, and here entirely in the radially median portion 81m.The zone 90 extends over a continuous surface representing at least 10%, and at most 80%, preferably at most 50% of the surface of each leading face 81a and trailing face 8 If of each first major transverse cutout 81.

[0113] As indicated above, this is also true for the second major transverse cutouts 82.

[0114] With reference to [Fig.3], each major transverse cutout 75 has a width that varies when moving radially in the major transverse cutout 75. At least 50%, preferably at least 75% of each major transverse cutout 75 and here each major transverse cutout 75 has a radially inner portion 75i, a radially middle portion 75m and a radially outer portion 75e. The radially inner portion 75i is arranged ra- radially inside the radially middle portion 75m. The radially outer portion 75e is arranged radially outside the radially middle portion 75m. The radially inner portion 75i is the radially innermost portion of the major transverse cutout 75 and the radially outer portion 75e is the radially outermost portion of the major transverse cutout 75. The radially middle portion 75m extends radially over a height H2' equal to 50% of the height H75 of the major transverse cutout 75. Each radially inner portion 75i and outer portion 75e extends radially respectively over a height Hl', H3' equal to 25% of the height H75 of the major transverse cutout 75.

[0115] At least 50%, preferably at least 75% and here each of the major transverse cutouts 75 formed in the central rib 65 have, in at least one zone 92, a width less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm. In the example shown in [Fig. 3], the width of at least 50%, preferably 75% and here of each of the major transverse cutouts 75 is less than or equal to 0.50 mm, preferably 0.40 mm and more preferably 0.35 mm over at least 10% of its height H, here represented by the portion of height H4', and over at least 10% of its length.

[0116] The zone 92 extends over a continuous surface representing at least 10%, preferably at least 20% and at most 80%, preferably at least 50% of the surface of each leading face 75a and trailing face 75f of each major transverse cutout 75.

[0117] In the section plane 111-111', each major transverse cutout 75 has a minimum width Lmin75 here equal to 0.24 mm. The zone 92 of at least 50%, preferably at least 75% and here of each of the major transverse cutouts 75 is located at least in part, and here entirely in the radially median portion 75m. This is also true for the major transverse cutouts 71, 72, 73, 74.

[0118] Comparative tests

[0119] Wear measurements

[0120] The tire 10 previously described was compared with a control tire T whose tread is illustrated in [Fig. 4]. The treads of the tires 10 and control tire T are made of an identical material. Unlike the tire 10, the control tire T is such that N1=N2 and such that there is no zone in which the width of the major transverse cutouts formed in each axially lateral portion is less than or equal to 0.50 mm. Indeed, the major transverse cutouts formed in each axially lateral portion have widths equal to 1.0 mm, 1.2 mm and 1.5 mm depending on the cutouts.

[0121] Four 10 and T tires were driven each time on the same vehicle and the wear of the tires mounted at the front of the vehicle was recorded as a function of the mileage over approximately 15,000 km. Then, in order to shorten the test, the wear was extrapolated until one of the portions of the tread reached the maximum wear indicated by the regulatory wear indicator. The average was then taken over the two tires mounted at the front of the vehicle.

[0122] We thus gathered the maximum mileage reached by each tire (which reflects the tire's lifespan) as well as the mass loss suffered by each tire upon reaching this maximum mileage. The results are gathered in Table 1 below using tire T as the base 100.

[0123] [Tables 1] T 10 Lifetime (base 100) 100 117 Mass loss (base 100) 100 94

[0124] Unlike the control tire T for which the service life is determined by the early reaching of the regulatory wear indicator on the axially lateral portion arranged on the inside of the vehicle, the service life of the tire 10 is determined by the later reaching of the regulatory wear indicator on the axially lateral portion arranged on the inside of the vehicle and almost simultaneously with the reaching of the regulatory wear indicator on the axially lateral portion arranged on the outside of the vehicle. Thus, the invention has made it possible to homogenize the wear of the tread and to avoid the early reaching of the wear limit by the most rigid portion of the tire. The tire according to the invention can therefore travel a mileage greater than that of the control tire T.

[0125] This is confirmed by the mass loss which is greater for the tire 10 compared to the mass loss of the control tire T. Indeed, due to more uniform wear over the entire tread, the tire 10 loses more mass until reaching the maximum mileage than the control tire T, most of whose portions still have a lot of material to wear while only one portion is worn (here the axially lateral portion arranged on the inside of the vehicle) to the point of reaching the regulatory wear indicator.

[0126] Noise assessment

[0127] Noise tests were carried out to evaluate the cavity noise at speeds below 90 km / h, the flapping noise and the braking noise of the 10 tire, the T tire and a particularly quiet reference tire R. These tests were carried out subjectively by a pilot and the results are collected in table 2 below in which: - the “=” sign indicates a noise substantially equivalent to that of the reference tire R, - the “-” sign indicates a slight increase in noise compared to the reference tire R, - the “—” sign indicates a significant increase in noise compared to the reference tire R, - the “+” sign indicates a slight reduction in noise compared to the reference tire R.

[0128] [Tables2] T 10 Cavity noise — = Beating noise - + Braking noise = +

[0129] It will be noted that the tire 10 according to the invention is quieter than the control tire T and even quieter than the reference tire R.

[0130] The invention is not limited to the embodiment described above.

Claims

Claims

1. A tire (10) comprising a tread (14) intended to come into contact with the ground when the tire (10) is rolling via a rolling surface (38), the tread (14) comprising: - main circumferential cutouts (51, 52, 53, 54, 55, 56) having a depth greater than or equal to 50% of the tread height (Hs) comprising first and second axially outer main circumferential cutouts (51, 52) arranged axially on either side of the median plane (M) of the tire (10), the first and second axially outer main circumferential cutouts (51, 52) being the axially outermost main circumferential cutouts of the tread (14), - a first axially lateral portion (PI) arranged axially outside the first axially outer main circumferential cutout (51) and extending axially from a first axial edge (41) of the rolling surface (38) to an axially outer edge (43) of the first axially outer main circumferential cutout (51), - a second axially lateral portion (P2) arranged axially outside the second axially outer main circumferential cutout (52) and extending axially from a second axial edge (42) of the rolling surface (38) to an axially outer edge (44) of the second axially outer main circumferential cutout (52), the first axially lateral portion (PI) comprising NI first transverse cutouts (81) formed in the first axially lateral portion (PI), the second axially lateral portion (P2) comprising N2 second transverse cutouts (82) formed in the second axially lateral portion (P2) with N2>N1, each first and second transverse cutout (81, 82), called major, extending over an axial width greater than or equal to 50% of the axial width respectively of each first and second axially lateral portion and having a depth greater than or equal to 50% of the tread height (Hs) of the tire (10), characterized in that at least 50% of the first major transverse cutouts (81) and at least 50% of the second major transverse cutouts (82) have, in at least one zone (90), a width less than or equal to 0.50 mm, the tire comprising k>l central rib(s) i (61, 62, 63, 64, 65) delimited axially by axially adjacent first and second main circumferential cutouts (51, 52, 53, 54, 55, 56), the or each central rib i (61, 62, 63, 64, 65) comprising Mi>l transverse cutouts (71, 72, 73, 74, 75) formed in said central rib i (61, 62, 63, 64, 65), each transverse cutout (71, 72, 73, 74, 75) made in said central rib i, called major, extending over an axial width greater than or equal to 50% of the axial width of said central rib i and having a depth greater than or equal to 50% of the tread height (Hs) of the tire (10),there is at least one central rib) (63, 64) comprising Mj>l major transverse cutouts (73, 74) made in said central rib) such that Nl <Mj<N2.,

2. Tire (10) according to the preceding claim, wherein at least 75% of the first major transverse cutouts (81) and at least 75% of the second major transverse cutouts (82), preferably each first major transverse cutout (81) and each second major transverse cutout (82) has, in at least one zone (90), a width less than or equal to 0.35 mm.

3. A tire (10) according to any preceding claim, wherein the zone (90) extends over at least 10% of the height and at least 10% of the length of at least 50% of the first major transverse cutouts (81) and at least 50% of the second major transverse cutouts (82).

4. A tire (10) according to any one of the preceding claims, wherein each first and second major transverse cutout (81, 82) has a radially middle portion (81m), a radially outer portion (81e) arranged radially outside the radially middle portion (81m) and a radially inner portion (81i) arranged radially inside the radially middle portion (81m), the radially middle portion (81m) extending radially over a height (H2) equal to 50% of the height (H) of said first and second major transverse cutout (81, 82), each radially inner (81i) and outer (81e) portion extending radially over a height (Hl, H3) equal to 25% of the height (H) of said first and second major transverse cutouts (81, 82), the zone (90) of at least 50% of the first major transverse cutouts (81) and at least 50% of the second major transverse cutouts (82), preferably of at least 75% of the first major transverse cutouts (81) and at least 75% of the second major transverse cutouts (82) and more preferably of each of the first and second major transverse cutouts (81, 82) is located at least partly in the middle portion (81m).

5. A tire (10) according to any one of the preceding claims, wherein at least 50% of the first major transverse cutouts (81) and at least 50% of the second major transverse cutouts (82), preferably at least 75% of the first major transverse cutouts (81) and at least 75% of the second major transverse cutouts (82) and more preferably each of the first and second major transverse cutouts (81, 82) has a radially inner portion (81i) and a radially outer portion (81e) arranged radially to the outside of the radially inner portion (81i), the radially inner portion (81i) being the radially innermost portion of said first and second major transverse cutouts (81, 82) and the radially outer portion (81e) being the radially outermost portion of said first and second major transverse cutouts (81, 82) major transverse (81, 82),the radially inner portion (81i) having a maximum width (Lmaxl) strictly greater than the maximum width (Lmax3) of the radially outer portion (81e).,

6. A tire (10) according to any preceding claim, wherein each first and second major transverse cutout (81, 82) extends axially from each first and second axial edge (41, 42) of the tread surface (38) respectively until it opens into each first and second axially outer main circumferential cutout (51, 52) respectively.

7. A tire (10) according to any preceding claim, wherein N2 / Nl>1.30 and preferably N2 / Nl>1.

50.

8. A tire (10) according to any one of the preceding claims preceding, in which each major transverse cutout (71, 72, 73, 74, 75) extends axially from each first main circumferential cutout (51, 52, 53, 54, 55, 56) until it opens into each second main circumferential cutout (51, 52, 53, 54, 55, 56).

9. Tire (10) according to the preceding claim, in which N2 / Mj > 1.15 and Mj / Nl>1.15 and preferably N2 / Mj > 1.25 and Mj / Nl>1.

25.

10. A tire (10) according to any one of the preceding claims, wherein NI, N2 and Mj are such that: - 0.40 < [(Nl / Rl) - (Mj x Rj)] / [(Mj / Rj) - (NI x RI)] < 0.60, - 0.40 < [(Mj / Rj) - (N2 x R2)] / [(N2 / R2) - (Mj x Rj)] < 0.60, and With: - RI being the pitch ratio equal to the ratio between the minimum distance between two first circumferentially consecutive major transverse cutouts (81) and the maximum distance between two first circumferentially consecutive major transverse cutouts (81), - R2 being the pitch ratio equal to the ratio between the minimum distance between two second circumferentially consecutive major transverse cutouts (82) and the maximum distance between two second major transverse cutouts (82) circumferentially consecutive, - Rj being the pitch ratio equal to the ratio between the minimum distance between two major transverse cutouts (71, 72, 73, 74,75) circumferentially consecutive of the or each central rib j (61, 62, 63, 64, 65) and the maximum distance between two major transverse cutouts (71, 72, 73, 74, 75) circumferentially consecutive of said or each central rib j.,

11. A tire (10) according to any one of the preceding claims, wherein NI, N2 and Mj are such that 0.50 < [Min(Nl x RI; N2 x R2; Mj x Rj) / Max(Nl / Rl; N2 / R2; Mj / Rj)]A(0.5) < 0.60 with: - RI being the pitch ratio equal to the ratio between the minimum distance between two first circumferentially consecutive major transverse cutouts (81) and the maximum distance between two first circumferentially consecutive major transverse cutouts (81), - R2 being the pitch ratio equal to the ratio between the minimum distance between two second circumferentially consecutive major transverse cutouts (82), Rj being the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive major transverse cutouts (71, 72, 73, 74, 75) of the or each central rib j (61, 62, 63, 64, 65) and the maximum distance between two circumferentially consecutive major transverse cutouts (71, 72, 73, 74, 75) of said or each central rib j, - Min(Nl x RI; N2 x R2; Mj x Rj) being the minimum value of the product between the number of major transverse cutouts (81, 82, 71, 72, 73, 74, 75) and the pitch ratio of the first and second axially outer portions (PI, P2) and of the or each central rib j (61, 62, 63, 64, 65), - Max(Nl / Rl; N2 / R2;Mj / Rj) being the maximum value of the ratio between the number of major transverse cutouts (81, 82, 71, 72, 73, 74, 75) and the pitch ratio of the first and second axially outer portions (PI, P2) and of the or each central rib j (61, 62, 63, 64, 65).;

12. Tyre (10) according to any one of the preceding claims, in which at least 50%, preferably at least 75% and more preferably each of the major transverse cutouts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65) have, in at least one zone (92), a width less than or equal to 0.50 mm.

13. Tire (10) according to the preceding claim, in which the zone (92) extends over at least 10% of the height and over at least 10% of the length of at least 50%, preferably at least 75% and more preferably of each of the major transverse cutouts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65).

14. A tire (10) according to claim 12 or 13, wherein each major transverse cutout (71, 72, 73, 74, 75) provided in the or each central rib i (61, 62, 63, 64, 65) has a radially median portion (75m), a radially outer portion (75e) arranged radially outside the radially median portion and a radially inner portion (75i) arranged radially inside the radially median portion (75m), the radially median portion (75m) being centrally median (75m) extending radially over a height equal to 50% of the height of said major transverse cutout (71, 72, 73, 74, 75), each radially inner and outer portion (75i, 75e) extending radially over a height equal to 25% of the height of said major transverse cutout (71, 72, 73, 74, 75), the zone (92) of at least 50% of the major transverse cutouts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65), preferably of at least 75% of the major transverse cutouts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65) and more preferably of each major transverse cutout (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65) is located at least partly in the middle portion (75m).

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