Tire with tread for uniform wear and low noise

Abstract

The present invention relates to a tire (10) provided with first and second main transverse cuts (81, 82) with N1 < N2, extending over an axial width that is 50% or more of the axial width of each of the first and second axial side portions (P1, P2) and having a depth that is 50% or more of the height of the tread pattern of the tire (10). At least 50% of the first main transverse cut (81) and at least 50% of the second main transverse cut (82) have a width of 0.50 mm or less in at least one region. There is at least one central rib j (63, 64) provided with main transverse cuts (73, 74) with Mj > 1 provided in the central rib j such that N1 < Mj < N2.

Description

[Technical Field]

[0001] The present invention relates to a tire for passenger vehicles. Tire is understood to mean a casing intended to cooperate with a support element, for example a rim, to form a cavity which can be pressurized to a pressure above atmospheric pressure. The tire according to the invention has a substantially toroidal structure which exhibits rotational symmetry about the main axis of the tire. [Background technology]

[0002] Tires for passenger cars sold under the trade name MICHELIN® as part of the PRIMACY4® series are known from the prior art. Such tires comprise a tread intended to come into contact with the ground via a tread surface when the tire is moving.

[0003] The tread has major circumferential cuts having a depth of at least 50% of the tread pattern height, including first and second axially outer major circumferential cuts located axially on opposite sides of a median plane of the tire, the first and second axially outer major circumferential cuts being the axially outermost major circumferential cuts of the tread.

[0004] The tread includes a first axial side portion disposed axially outward of the first axially outer major circumferential cut and a second axial side portion disposed axially outward of the second axially outer major circumferential cut, and also includes a lateral cut at least partially formed in each of the first and second axial side portions.

[0005] Despite its superior performance characteristics, this prior art tire exhibits uneven wear. Specifically, it has been found that on some vehicles equipped with this tire, one of the first and second axial sides wears more rapidly than the other. When the tread wears to a regulatory wear threshold, the tire must be replaced, even if there is still a significant amount of wearable material in the remainder of the tire. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to increase the useful life of a tire by reducing uneven tread wear between the first axial side and the second axial side. [Means for solving the problem]

[0007] The present invention therefore relates to a tire comprising a tread intended to come into contact with the ground during running through its tread surface, said tread comprising: main circumferential cuts having a depth of 50% or more of the tread pattern height, comprising first and second axially outer main circumferential cuts arranged on both axial sides of the median plane of the tire, the first and second axially outer main circumferential cuts being the axially outermost main circumferential cuts of the tread; a first axial side portion disposed axially outward of the first axially outer main circumferential notch and extending axially from a first axial edge of the tread surface to an axially outer edge of the first axially outer main circumferential notch; a second axial side portion disposed axially outward of the second axially outer main circumferential notch and extending axially from the second axial edge of the tread surface to the axial outer edge of the second axially outer main circumferential notch; Equipped with the first axial side includes a first transverse cut N1 formed in the first axial side; the second axial side includes N2 second transverse cuts formed in the second axial side, where N2>N1; each of the first and second lateral cuts, referred to as a major lateral cut, extends across an axial width of at least 50% of the axial width of each of the first and second axial sides and has a depth of at least 50% of the tread pattern height of the tire; at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts have a width of 0.50 mm or less in at least one zone; The tire includes a central rib i of k≧1 delimited by first and second main circumferential cuts adjacent in the axial direction, and the or each central rib i includes lateral cuts of Mi>1 formed in the central rib i, and each lateral cut formed in the central rib i is called a main lateral cut and extends over an axial width of 50% or more of the axial width of the central rib i and has a depth of 50% or more of the tread pattern height of the tire. The tire has at least one central rib j having main lateral cuts of Mj>1 formed in the central rib j such that N1<Mj<N2.

[0008] According to the present invention, while reducing the noise generated from the tread, by making the wear of the tread more uniform between the first axial side portion and the second axial side portion, it becomes possible to extend the service life of the tire.

[0009] Specifically, the inventors of the present invention have discovered that since the engine torque passes through the most rigid part of the tread, the most rigid part of the tread is the part that wears most rapidly. When there is a large difference in rigidity between two parts of the tread as in the prior art tires described above, uneven wear is observed, and as a result, the service life is shortened. The difference in rigidity is explained by the fact that in the case of prior art tires, the number N2 of the second main lateral cuts formed in the second axial side portion is larger than the number N1 of the first main lateral cuts formed in the first axial side portion. Specifically, since the number of the second cuts is relatively large, the second axial side portion is less rigid than the first axial side portion.

[0010] To reduce or even eliminate the more rapid wear of the first axial side, the inventors conceived the idea of ​​creating at least one zone (having a width of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less) between the front and rear faces of a significant number (at least 50%) of the second main transverse cuts when the tire is in operation, thereby preventing relative movement of the blocks separated by the second main transverse cuts and thus hiding the lower stiffness of the second axial side. Specifically, thanks to this zone, it is easier to immobilize the blocks having the front and rear faces when the tire is in operation, which has the effect of making this second axial side more stiff. In the same way, the blocks separated by the first main transverse cuts are also immobilized. In this way, regardless of the number of cuts on the first and second axial sides, each of these first and second axial sides is stiffened in an equivalent manner, resulting in equal wear between the first and second axial sides.

[0011] The value of 0.50 mm was determined by the inventors as the value below which contact between the front and rear surfaces is observed under the overwhelming majority of observed driving conditions (load, speed, inflation pressure, etc.) Above this value of 0.50 mm, the front and rear surfaces may still come into contact with each other, but only under extreme driving conditions that do not reflect normal use of the tire.

[0012] A zone having a width of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less, may shrink to two points on the front and rear surfaces that are separated from each other by a distance of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less, or may spread over a surface that does not shrink to the two points on the front and rear surfaces. In the case of the surface that does not shrink to the two points on the front and rear surfaces, a plurality of points on each of the front and rear surfaces are separated from each other in pairs by a distance of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less. Due to the feature of N2 / N1>1, it becomes possible to particularly reduce the noise generated from the tire. Specifically, each axial direction portion of the tread generates noise, and its harmonics are centered on frequencies particularly dependent on the number and distribution of the lateral cuts formed in this axial direction portion of the tread. In order to reduce the noise generated from the tire, the inventors have found that it is effective to disperse the frequencies of the harmonics of different axial direction portions of the tread, and thus disperse the acoustic energy generated from the tire. In order to disperse these frequencies, the tire according to the present invention is configured such that the first and second axial side portions have different numbers of main lateral cuts, making it possible to differentiate the harmonics related to each of the first and second axial side portions, and thus reduce the noise generated from the tire. Similarly, due to the feature of N1<Mj<N2 by the central rib j in which the main lateral cuts of Mj are formed, it becomes possible to disperse the acoustic energy generated from the tire, and thus reduce the noise generated from the tire.

[0013] Conventionally, the tread surface is axially bounded by first and second axial edges. The first and second axial edges of the tread surface are determined for a tire mounted on a nominal rim and inflated to a nominal pressure in accordance with the European Tire and Rim Technical Organization (ETRTO) standard (2021). The first and second axial edges of the tread surface are located on either side of the tire's median plane and are formed by lines substantially parallel to the tire's circumferential direction. When there is a clear boundary between the tread surface and the rest of the tire, the first and second axial edges of the tread surface are easily determined. When the tread surface is continuous with the outer surface of the tire's sidewalls, the first and second axial edges can be determined by taking into account that each of the first and second axial edges passes through a point in each meridian section, at which point the angle between a tangent to the tread surface passing through this point and a straight line parallel to the axial direction is equal to 30°. If there are multiple points in the meridional section where the angle is equal to 30° in absolute value, the outermost radial point is used.

[0014] The or each first and second axial side of the tread may of course be provided with further lateral cuts other than the first and second main lateral cuts, and the or each first and second axial side of the tread may also be provided with further cuts other than the major or minor lateral cuts, for example circumferential cuts.

[0015] A cut or cut portion has two main characteristic dimensions in the tread surface: width and curvature length, such that the curvature length is at least equal to twice the width. Thus, a cut determines its curvature length and is bounded by at least two major sides that meet at their base and are separated from each other by a non-zero distance called the cut width.

[0016] For a new tire, the width of a cut is the maximum distance between the two major sides of the cut, measured at the radial dimension coincident with the tread surface if the cut is not chamfered, and at the outermost radial dimension of the cut, radially inward of the chamfer if the cut is chamfered. This width is measured substantially perpendicular to the major sides. If a width other than the specified width is specified, for example, if a width at a particular dimension is specified, then the width is equal to the minimum distance between the two major sides of the cut at the particular dimension.

[0017] For a new tire, the depth of the cut is the maximum radial distance between the bottom of the cut and its projection on the ground when the tire is running. The maximum value of the depth of the cut is called the tread pattern height.

[0018] The cuts can be transverse or circumferential.

[0019] The lateral cuts are such that they extend in an average direction that forms an angle with the circumferential direction of the tire strictly greater than 30°, preferably greater than or equal to 45°, i.e., an angle with the axial direction of the tire not greater than 60°, preferably not greater than 45°. The average direction is the shortest curve connecting the two ends of the cut and is parallel to the tread surface. A lateral cut may be continuous, i.e., not interrupted by a tread block or another cut, so that the two major sides determining its length are uninterrupted along the length of the lateral cut. A lateral cut may also be discontinuous, i.e., interrupted by one or more tread blocks and / or one or more cuts, so that the two major sides determining its length are interrupted by one or more tread blocks and / or one or more cuts.

[0020] The circumferential cuts are such that they extend in an average direction that forms an angle of not more than 30°, preferably not more than 10°, with the circumferential direction of the tire, i.e., an angle of strictly more than 60°, preferably strictly more than 80°, with the axial direction of the tire. The average direction is the shortest curve connecting the ends of the cut and is parallel to the tread surface. In the case of a continuous circumferential cut, its ends coincide with each other and are connected by a curve that goes around the tire once. A circumferential cut is continuous, i.e., it may not be interrupted by a tread block or another cut, so that the two main sides that determine its length are uninterrupted around the entire circumference of the tire. A lateral cut may also be discontinuous, i.e., it may be interrupted by one or more tread blocks and / or one or more cuts, so that the two main sides that determine its length are interrupted by one or more tread blocks and / or one or more cuts around the entire circumference of the tire.

[0021] In the case of a lateral cut, the sides are called leading and trailing faces, each provided with a leading edge and a trailing edge respectively, the leading edge being the edge which, for a given circumferential line, enters the contact patch before the trailing edge.

[0022] Optionally, in embodiments for improving braking on dry ground, the or each lateral cut is chamfered. The chamfer of a lateral cut can be an angular chamfer or a rounded chamfer. An angular chamfer is formed by a flat surface that is inclined relative to the front or rear face and extends to a leading or trailing edge that circumferentially bounds the lateral cut. A rounded chamfer is formed by a curved surface that extends tangentially to the front or rear face. The chamfer of a lateral cut is characterized by a height and width that are equal to the radial distance and the distance perpendicular to the front or rear face, respectively, between the common point between the leading or trailing face that is extended by the chamfer and the leading or trailing edge that circumferentially bounds the lateral cut.

[0023] Optionally, in some embodiments to improve braking on wet ground and also lateral blipping on dry ground, at least one of the major circumferential cuts is chamfered. The chamfer of the circumferential cut can be a square chamfer or a round chamfer. A square chamfer is formed by a flat surface that is inclined relative to the inner and outer axial surfaces and extends to the inner or outer axial edge that axially bounds the circumferential cut. A round chamfer is formed by a curved surface that tangentially merges with the inner or outer axial surface. The chamfer of the circumferential cut is characterized by a height and width equal to the radial and axial distances, respectively, between the common points between the inner or outer axial surface that is extended by the chamfer and the inner or outer axial edge that axially bounds the circumferential cut.

[0024] The tire according to the invention has a substantially toroidal shape about an axis of rotational symmetry that substantially coincides with the axis of rotation of the tire and that defines the three directions conventionally used by those skilled in the art: axial, circumferential and radial.

[0025] The expression "axial" means a direction substantially parallel to the axis of rotational symmetry of the tire, i.e. the axis of rotation of the tire.

[0026] The expression "circumferential direction" means a direction substantially perpendicular to the axial direction and to the radial direction of the tire (in other words tangent to a circle centered on the axis of rotation of the tire) in each meridian plane.

[0027] The term "radial" means any direction along the radius of the tire, i.e., any direction intersecting the axis of rotation of the tire and substantially perpendicular to that axis.

[0028] The expression "median plane" (denoted M) means a plane perpendicular to the axis of rotation of the tire, located axially midway between the two beads and passing through the axial center of the crown reinforcement.

[0029] The expression "equatorial circumferential plane of the tire" means a plane passing through the tire's equator in a meridian section, perpendicular to the median plane and the radial direction. The tire's equator is the axis parallel to the tire's axis of rotation in a meridian section (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions) and equidistant between the radially outermost point of the tread intended to come into contact with the ground and the radially innermost point of the tire intended to come into contact with a support, for example the rim.

[0030] The expression "median plane" means a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0031] The expressions "radially inward of" and "radially outward of" mean "closer to" and "farther from" respectively. "Axially inward of" and "axially outward of" mean "closer to" and "farther from" respectively.

[0032] The term "bead" means the part of the tire intended to enable the tire to be mounted on a mounting support, for example on a wheel with a rim. Each bead is therefore intended in particular to come into contact with the flange of the rim to enable the tire to be mounted.

[0033] An interval of values ​​expressed by the expression "between a and b" denotes a range of values ​​extending from greater than a to less than b (i.e. excluding the limit values ​​a and b), whereas an interval of values ​​expressed by the expression "from a to b" means a range of values ​​extending from a to b (i.e. including the precise limit values ​​a and b).

[0034] In a preferred embodiment of the invention, the tire is intended for passenger cars defined in accordance with the European Tire and Rim Technical Organization, or "ETRTO," standard (2021). Such tire has a cross-section, in the sense of the European Tire and Rim Technical Organization, or "ETRTO," standard (2021), characterized in meridian section by a section height H and a nominal section width S, such that the ratio H / S, expressed as a percentage, is at most equal to 90, preferably at most equal to 70 and 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. Furthermore, the flange diameter D, which defines the diameter of the rim on which the tire is mounted, is at least equal to 12 inches, preferably at least equal to 16 inches and at most equal to 24 inches.

[0035] In a preferred embodiment of the invention, the tire is a "summer" tire, by which is understood a tire which is neither a "four-season" tire, nor an "all-season" tire, nor a "winter" tire.

[0036] Winter tires are particularly identified by the M+S marking (M+S stands for "Mud + Snow") and / or the 3PMSF marking (3PMSF stands for "3 Peak Mountain Snow Flake"). Four-season or all-season tires also have the M+S and / or 3PMSF markings for snow performance. Summer tires therefore do not have the M+S or 3PMSF markings.

[0037] In an embodiment for further equalizing wear between the first and second axial sides, at least 75% of the first major transverse cuts and at least 75% of the second major transverse cuts, preferably each first major transverse cut and each second major transverse cut, have a width of 0.35 mm or less in at least one zone.

[0038] Optionally and preferably, at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts have a width of 0.40 mm or less, more preferably 0.35 mm or less, in at least one zone. Reducing the width of the zones further facilitates contact between the anterior and posterior surfaces.

[0039] Optionally and preferably, at least 75% of the first major transverse cuts and at least 75% of the second major transverse cuts, preferably each first major transverse cut and each second major transverse cut, have a width of 0.40 mm or less, more preferably 0.35 mm or less, in at least one zone.

[0040] Optionally and preferably, the zone extends over at least 10% of the height and along at least 10% of the length of at least 50% of the first major transverse cut and at least 50% of the second major transverse cut. By increasing the height and length over which the blocks can contact each other, front and rear surface contact is more easily achieved.

[0041] Optionally and preferably, the zones extend over a continuous surface corresponding to at least 10%, preferably at least 20%, of the surface of each of the front and rear faces for at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts, thus maximizing the ability of the front and rear faces to come into contact with each other at spot contact points.

[0042] Advantageously, the zone extends over a continuous surface representing at most 80%, preferably at most 50%, of the surface of each front and rear face for at least 50% of the first main transverse cut and at least 50% of the second main transverse cut.

[0043] 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 front and rear face for at least 75% of the first major transverse cut, very preferably for each first major transverse cut and at least 75% of the second major transverse cut, very preferably for each second major transverse cut.

[0044] In any preferred embodiment, each of the first and second main transverse cuts has a radially central portion, a radially outer portion located radially outside the radially central portion, and a radially inner portion located radially inside the radially central portion, the radially central portion extending radially over a height equal to 50% of the height of the first and second main transverse cuts, each of the radially inner and radially outer portions extending radially over a height equal to 25% of the height of the first and second main transverse cuts, and the zone of at least 50% of the first main transverse cut and at least 50% of the second main transverse cut, preferably at least 75% of the first main transverse cut and at least 75% of the second main transverse cut, more preferably of each of the first and second main transverse cuts, is at least partially located in the radially central portion.

[0045] This ensures that the contact between the front and rear surfaces occurs in the radially central portion, which allows the first and second main cuts to have relatively large widths in other portions, particularly in the radially outer portions, thereby increasing the area porosity.

[0046] In certain embodiments, at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts, preferably at least 75% of the first major transverse cuts and at least 75% of the second major transverse cuts, more preferably each of the first and second major transverse cuts has a radially inner portion and a radially outer portion disposed radially outward of the radially inner portion, the radially inner portion being the radially innermost of the first and second major transverse cuts, the radially outer portion being the outermost of the first and second major transverse cuts, and the radially inner portion having a maximum width strictly greater than the maximum width of the radially outer portion. By using main transverse cuts with radially variable maximum widths, the occurrence of chunking of blocks is minimized, particularly at the second axial side portion.

[0047] In an advantageous but optional embodiment, the tire has an inner side and an outer side that are imposed when it is mounted on a vehicle, the first axial side being located on the same side of the median plane as the outer side and the second axial side being located on the same side of the median plane as the inner side.

[0048] The expression "inner side and outer side as imposed when the tire is mounted on a vehicle" means that the tire is designed so that one side is positioned on the inner side and the other side is positioned on the outer side. The tire manufacturer imposes this orientation to ensure that the tire performs as expected. Specifically, mounting the tire in an orientation different from the orientation imposed by the manufacturer may result in dangerous vehicle behavior. The expression "outer side" means the side of the tire that is fully visible from the outside of the vehicle when the tire is mounted on the vehicle. The expression "inner side" means the side of the tire that faces the wheel arch of the vehicle on which the tire is mounted. Typically, tires have markings that indicate the inner and outer sides.

[0049] In an advantageous but optional embodiment, each of the first and second major transverse cuts extends axially from each of the first and second axial edges of the tread surface to open into each of the first and second axially outer major circumferential cuts, respectively, thus promoting mobility of the blocks of the first and second axially outer portions, thereby improving tire flattening and therefore rolling resistance.

[0050] In other embodiments, it can be envisaged that each first and / or each second major transverse cut does not open into the adjacent first and second axially outer major circumferential cuts, respectively, and in these variants the main transverse cuts are said to be blind.

[0051] In an advantageous embodiment, N2 / N1≧1.30, preferably N2 / N1≧1.50. By further differentiating the number of first and second main transverse cuts formed in each of the first and second axial sides, respectively, the noise generated by the tire is reduced even further.

[0052] Advantageously, N2 / N1≦2.00, preferably N2 / N1≦1.75. Excessively different numbers of the first and second main transverse cuts formed in each of the first and second axial sides will result in a relatively large difference between the stiffness of the first and second axial sides, which will increase the risk of uneven wear.

[0053] In a preferred variant, the ratio C / N2 ranges from 14 to 20, preferably from 16 to 19. In another preferred variant, compatible with the above preferred variant, the ratio C / N1 ranges from 24 to 30, preferably from 27 to 29. In these ratios, C is the value of the circumference of the unmounted and uninflated tire, expressed in millimeters.

[0054] Although advantageous, in any embodiment, each main transverse cut formed in each central rib i extends axially from each first main circumferential cut to open into each second main circumferential cut. Accordingly, the mobility of the blocks of each central rib is promoted, thereby improving the flattening of the tire and thus the rolling resistance.

[0055] In an optional advantageous embodiment, each central rib i other than the central rib j has a main transverse cut with Mm > 1. This main transverse cut is formed in the central rib i other than the central rib j and extends over an axial width of 50% or more of the axial width of the central rib i other than the central rib j, has a depth of 50% or more of the tread pattern height of the tire, and for each central rib i other than the central rib j, N1 ≤ Mm ≤ Mj < N2 or N1 < Mj ≤ Mm ≤ N2. Accordingly, the acoustic energy generated from the tire is further dispersed, and thus the noise generated from the tire is reduced.

[0056] In a specific variant, Mi = Mm, which means that all of the transverse cuts formed in the central rib i are main transverse cuts. In another variant, Mi > Mm, which means that some of the transverse cuts formed in the central rib i are not main transverse cuts.

[0057] In an advantageous and optional variant, N2 / Mj ≥ 1.15 and Mj / N1 ≥ 1.15, preferably N2 / Mj ≥ 1.25 and Mj / N1 ≥ 1.25. By further differentiating the number Mj of main transverse cuts compared to the number of the first and second main transverse cuts formed in each of the first and second axial side portions respectively, the noise generated from the tire is further reduced.

[0058] Advantageously, N2 / Mj≦1.75 and Mj / N1≦1.75, preferably N2 / Mj≦1.50 and Mj / N1≦1.50. Excessive differences in the number of main transverse cuts made in the central rib j in which the main transverse cuts Mj are made will result in a relatively large difference between the stiffness of the first and second axial side portions, on the one hand, and the stiffness of the central rib j in which the main transverse cuts Mj are made, on the other hand, which will increase the risk of uneven wear.

[0059] In a preferred variant, the ratio C / Mj ranges from 18 to 23, preferably from 20 to 23. As before, C is the value of the circumference of the unmounted and uninflated tire, expressed in millimeters.

[0060] In a preferred optional embodiment, N1, N2 and Mj are 0.40≦[(N1 / R1)-(Mj×Rj)] / [(Mj / Rj)-(N1×R1)]≦0.60, 0.40≦[(Mj / Rj)-(N2×R2)] / [(N2 / R2)-(Mj×Rj)]≦0.60, where R1 is a pitch ratio equal to the ratio of the minimum distance between two circumferentially consecutive first main transverse cuts to the maximum distance between two circumferentially consecutive first main transverse cuts; R2 is a pitch ratio equal to the ratio of the minimum distance between two circumferentially consecutive second major transverse cuts to the maximum distance between two circumferentially consecutive second major transverse cuts; Rj is the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive main transverse notches of the or each central rib j and the maximum distance between two circumferentially consecutive main transverse notches of the or each central rib j.

[0061] In these preferred embodiments, an acoustic overlap level is determined between the first axially outer portion and the or each central rib j on the one hand, and between the second axially outer portion and the or each central rib j on the other hand. The lower these overlap levels, the more acoustic energy is dispersed, thereby making it possible to reduce the noise generated by the tire. Nevertheless, it is preferable that the overlap level is not too low, since a too low overlap level increases the risk of frequency modulation and thus of beat noise.

[0062] In a preferred optional embodiment, N1, N2, and Mj are such that 0.50≦[Min(N1×R1; N2×R2; Mj×Rj) / Max(N1 / R1; N2 / R2; Mj / Rj)]^(0.5)≦0.60, R1 is a pitch ratio equal to the ratio of the minimum distance between two circumferentially consecutive first main transverse cuts to the maximum distance between two circumferentially consecutive first main transverse cuts; R2 is a pitch ratio equal to the ratio of the minimum distance between two circumferentially consecutive second major transverse cuts to the maximum distance between two circumferentially consecutive second major transverse cuts; Rj is a pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive main transverse cuts for the or each central rib j and the maximum distance between two circumferentially consecutive main transverse cuts for the or each central rib j; Min(N1×R1; N2×R2; Mj×Rj) is the minimum value for the product of the number of major transverse cuts and the pitch ratio of the first and second axially outer portions and the or each central rib j; Max(N1 / R1; N2 / R2; Mj / Rj) is the maximum value for the ratio between the number of major transverse cuts and the pitch ratio of the first and second axially outer portions and the or each central rib j.

[0063] In these preferred embodiments, an overall pitch ratio is determined between the first axially outer portion, the or each central rib j, and the second axially outer portion. A lower overall pitch ratio allows for better dispersion of acoustic energy, thereby reducing noise generated by the tire. Nevertheless, it is preferable that the overall pitch ratio is not too low, as this would result in excessive differences in stiffness and an increased risk of localized wear.

[0064] In any preferred embodiment, at least 50%, preferably at least 75%, more preferably each of the main transverse cuts formed in the or each central rib i have a width of 0.50 mm or less in at least one zone. To hide potential stiffness differences between the or each central rib i and the first and second axial sides, the or each central rib i is stiffened in an equivalent manner to ensure equal wear between the or each central rib i and the first and second axial sides.

[0065] Preferably, at least 50%, preferably at least 75%, more preferably each of the main transverse cuts formed in the or each central rib i have a width in at least one zone of 0.40 mm or less, more preferably 0.35 mm or less.

[0066] In a preferred variant, this zone extends over at least 50%, preferably at least 75%, more preferably for each of the main transverse cuts formed in the or central rib i, over at least 10% of its height and along at least 10% of its length. By increasing the height and length over which the blocks can contact each other, contact between the front and rear faces is further facilitated.

[0067] Optionally and preferably, the zone extends over a continuous surface corresponding to at least 10%, preferably at least 20%, of the surface of each of the front and rear faces of at least 50% of the major transverse cuts formed in the or each central rib i, thus maximizing the ability of the front and rear faces to come into contact with each other in terms of spot contact points.

[0068] Advantageously, the zone extends over a continuous surface representing at most 80%, preferably at most 50%, of the surface of each of the front and rear faces of at least 50% of the main transverse cuts formed in the or each central rib i.

[0069] Even more preferably, the zone extends over a continuous surface of at least 75% of the main transverse cut formed in the or each central rib i, very preferably representing for each at least 10%, preferably at least 20%, at most 80%, preferably at most 50% of the surface of each front and rear face.

[0070] In a preferred optional embodiment, each main transverse cut formed in the or each central rib i has a radially central portion, a radially outer portion arranged radially outside the radially central portion, and a radially inner portion arranged radially inside the radially central portion, wherein the radially central portion extends radially over a height equal to 50% of the height of the main transverse cut, and each of the radially inner and radially outer portions extends radially over a height equal to 25% of the height of the main transverse cut, and wherein the zone of at least 50% of the main transverse cuts formed in the or each central rib i, preferably at least 75% of the main transverse cuts formed in the or each central rib i, more preferably each main transverse cut formed in the or each central rib i, is at least partially located in the radially central portion.

[0071] As with the first and second major transverse cuts, this ensures that the contact between the front and rear faces occurs in the radially central portion, which therefore allows the major transverse cuts to have a relatively large width in other portions, particularly in the radially outer portions, thereby increasing the areal porosity.

[0072] In certain preferred variants, there is at least one central rib i with the same number of main transverse notches as there are first axial sides, and / or there is at least one central rib i with the same number of main transverse notches as there are second axial sides. These variants make it possible to create a visual continuity between the first and second axial sides and a portion of the central rib. Even more preferably, the or one of the ribs with the same number of main transverse notches as there are first axial sides is the rib axially adjacent to the first axial side, and / or the or one of the ribs with the same number of main transverse notches as there are second axial sides is the rib axially adjacent to the second axial side.

[0073] In an embodiment for further reducing noise generated by the tire, each main transverse cut is formed in the or each central rib i until it opens into each of first and second circumferential cuts axially separating the central rib i in first and second opening zones, respectively, wherein the azimuth angle of a point of the first opening zone of the first main transverse cut formed in the central rib i is substantially aligned in the circumferential direction with the azimuth angle of a point of the second opening zone of the second main transverse cut formed in the central rib i, and the first and second main transverse cuts formed in the central rib i are adjacent in the circumferential direction.

[0074] The term "substantially aligned" means that their azimuth angles are circumferentially separated from one another by a maximum of 5% of the average distance separating circumferentially adjacent first and second major transverse cuts formed in that central rib i.

[0075] Preferably, each main circumferential cut has a depth of at least 75% of the tread pattern height, more preferably at least 90%.

[0076] In embodiments where the major circumferential cuts are relatively deep and suitable for passenger car or van tires, each major circumferential cut has a depth ranging from 4.0 mm to the tread pattern height, preferably from 5.0 mm to the tread pattern height, and more preferably from 5.5 mm to the tread pattern height.

[0077] In embodiments where the main circumferential cuts are relatively wide main circumferential grooves suitable for passenger car or van tires, each main circumferential cut has an axial width of at least 1.0 mm, preferably at least 5.0 mm, and more preferably in the range of 5.0 mm to 13.0 mm.

[0078] In a conventional manner, a tire comprises a crown, two sidewalls, and two beads, each sidewall connecting a respective bead to the crown. The crown also conventionally comprises a tread and a crown reinforcement disposed radially inward of the tread. The tire also comprises a carcass reinforcement radially inward of the crown reinforcement, anchored to each bead and extending radially within each sidewall and axially within the crown.

[0079] In conventional manner, the crown reinforcement comprises at least one crown layer containing reinforcing elements, preferably textile or metal thread elements.

[0080] In an embodiment for obtaining the performance aspects of a tire known as a radial tire, for example as defined by the ETRTO, the carcass reinforcement comprises at least one carcass layer, the or each carcass layer comprising filamentary carcass reinforcing elements, each of which extends in a main direction substantially forming an angle with the circumferential direction of the tire ranging from 80° to 90° in absolute value.

[0081] The invention will be better understood on reading the following description, given purely by way of non-limiting example and in conjunction with the drawings in which: [Brief explanation of the drawings]

[0082] [Figure 1] 1 is a top view of the tread of a tire according to the present invention; [Figure 2] 2 is a cross-sectional view of the main transverse cut in plane II-II' of FIG. 1; [Figure 3] 3 is a cross-sectional view of the main transverse cut in plane III-III' of FIG. 1; [Figure 4] 2 is a view similar to FIG. 1 for a control tire that allows the advantages of the invention to be demonstrated. DETAILED DESCRIPTION OF THE INVENTION

[0083] Reference frames X, Y, Z are shown corresponding to the normal axial (Y), radial (Z) and circumferential (X) directions of the tire, respectively.

[0084] With reference to Figure 1, a tire according to the invention is generally designated by the reference numeral 10. The tire 10 has a substantially toroidal shape about an axis of rotational symmetry substantially parallel to the axial direction Y. The tire 10 is intended for passenger cars and has the dimensions 235 / 55R19. The tire 10 is a summer tire. The tire 10 is shown as new, i.e., before it has been driven.

[0085] The tire 10 comprises a tread 14 intended to come into contact with the ground during travel and has a conventional structure, for example as described in applications WO 2021 / 250331, WO 2022 / 074341 or WO 2022 / 069819.

[0086] The tire 10 is obtained by molding a green tire in a mold with a number of different patterns. In Figure 1, the joint J between two circumferentially adjacent patterns is shown by a continuous line. In this case, the mold has three different patterns randomly distributed to form the tread 14.

[0087] The tread 14 has a tread surface 38 that is intended to contact the ground as the tire 10 travels over the ground. The tread surface 38 is bounded axially by first and second axial edges 41, 42. The tire 10 has an inner side INT and an outer side EXT that are imposed when the tire 10 is mounted on a vehicle.

[0088] The tread 14 includes an axially central portion P0 and first and second axial side portions P1, P2 disposed axially outward of the axially central portion P0 on either side of the axially central portion P0 with respect to a median plane M of the tire 10. The first axial side portion P1 is disposed on the same side of the median plane as the outer lateral surface EXT, and the second axial side portion P2 is disposed on the same side of the median plane as the inner lateral surface INT.

[0089] The tread 14 comprises N>1 main circumferential cuts, in this case N=6 main circumferential grooves designated 51, 51, 52, 53, 54, 56. The axially outer main circumferential cuts, referred to as the first and second axially outer main circumferential cuts 51, 52, are located axially on either side of the median plane M of the tire 10 and are the axially outermost main circumferential cuts of the tread 14.

[0090] The first axial side portion P1 and the second axial side portion P2 are disposed axially outward of the first axially outer major circumferential notch 51 and the second axially outer major circumferential notch 52, respectively. The first axial side portion P1 extends axially from the first axial edge 41 of the tread surface 38 to the axially outer edge 43 of the first axial major circumferential notch 51. The second axial side portion P2 extends axially from the second axial edge 42 of the tread surface 38 to the axially outer edge 44 of the second axial major circumferential notch 52.

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

[0092] Each of the main circumferential cuts 51-56 has an axial width of 1.0 mm or more, preferably 5.0 mm or more, and more preferably in the range of 5.0 mm to 13.0 mm. In this case, the width of each of the first and second axially outer main circumferential cuts 51, 52 and each of the main circumferential cuts 53, 56 is equal to 8.4 mm, the width of main circumferential cut 54 is equal to 9.0 mm, and the width of main circumferential cut 55 is equal to 9.5 mm.

[0093] The axially central portion P0 has k≧1 central ribs, and in this example, k=5 central ribs 61, 62, 63, 64, 65. Each of the central ribs 61-65 is disposed axially between first and second axially adjacent main circumferential cuts among the main circumferential cuts 51-56, and in this example, is axially separated by the first and second axially adjacent main circumferential cuts among the main circumferential cuts 51 and 56.

[0094] The first axial side P1 includes a first lateral cut 81 N1 formed in the first axial side P1. The second axial side P2 includes a second lateral cut 82 N2 formed in the second axial side P2.

[0095] Each central rib 61, 62, 63, 64 and 65 respectively includes transverse cuts M61, M62, M63, M64 and M65 formed therein and designated by the reference numerals 71, 72, 73, 74 and 75, respectively.

[0096] Each lateral cut 81, 82 extends over 50% or more of the axial width of each of the first and second axial sides P1, P2, respectively, and in this case over an axial width that is greater than the axial width of each of the first and second axial sides P1, P2. Each of the first and second lateral cuts 81, 82 therefore extends axially from each of the first and second axial edges 41, 42, respectively, until it opens into each of the first and second axially outer main circumferential cuts 51, 52, respectively. Each lateral cut 81, 82 has a depth that is 50% or more of the tread pattern height Hs of the tire 10, and in this case has a depth equal to 5.3 mm.

[0097] Each of the transverse cuts 71, 72, 73, 74, and 75 extends over an axial width equal to 100% of the axial width of each of the central ribs 61, 62, 63, 64, and 65, which in this case is 50% or more of the axial width of each of the central ribs 61, 62, 63, 64, and 65. Accordingly, each of the transverse cuts 71, 72, 73, 74, and 75 extends axially from each of the first major circumferential cuts 51, 53, 54, 55, 56 to open into each of the second major circumferential cuts 53, 54, 55, 56, 52, respectively. Each of the transverse cuts 71, 72, 73, 74, and 75 has a depth of 50% or more of the tread pattern height Hs of the tire 10. In this case, the cuts 71, 75 have a depth equal to 6.0 mm, the cuts 72, 74 have a depth equal to 6.2 mm, and the cut 73 has a depth equal to 6.3 mm.

[0098] The transverse cuts 81, 82, 71, 72, 73, 74, and 75 are called major transverse cuts based on the ratio of their axial width as they extend on the axial side portions or on the central ribs and the ratio of their depth to the height of the tread pattern.

[0099] For each of the central ribs 61, 62, 65, N1 ≦ M61 ≦ Mj < N2 or N1 < Mj ≦ M61 ≦ N2, N1 ≦ M62 ≦ Mj < N2 or N1 < Mj ≦ M62 ≦ N2, and N1 ≦ M65 ≦ Mj < N2 or N1 < Mj ≦ M65 ≦ N2. In this case, among the central ribs 61, 62, 65, there is at least one central rib having the same number of major transverse cuts as the first axial side portion P1. In this case, for the central ribs 61 and 62 that are axially adjacent to the first axial side portion P1, M61 = M62 = N1 = 83. Also, among the central ribs 61, 62, 65, there is at least one central rib having the same number of major transverse cuts as the second axial side portion P2. In this case, for the central rib 65 that is axially adjacent to the second axial side portion P2, M65 = N2 = 134. Note that N1 and N2 satisfy N2 / N1 ≧ 1.30, preferably N2 / N1 ≧ 1.50 and N2 / N1 ≦ 2.00, preferably N2 / N1 ≦ 1.75, and in this case, N2 / N1 = 1.61.

[0100] Among the central ribs 61 to 65, there is at least one central rib j having a main lateral cut such that N1 < Mj < N2. In this case, for the central ribs 63 and 64, M63 = M64 = 106. Note that N1, N2, M63, and M64 satisfy N2 / M63 = N2 / M64 ≥ 1.15 and M63 / N1 = M64 / N1 ≥ 1.15, preferably N2 / M63 = N2 / M64 ≥ 1.25 and M63 / N1 = M64 / N1 ≥ 1.25. Also note that N2 / M63 = N2 / M64 ≤ 1.75 and M63 / N1 = M64 / N1 ≤ 1.75, preferably N2 / M63 = N2 / M64 ≤ 1.50 and M63 / N1 = M64 / N1 ≤ 1.50.

[0101] R1 can be defined as a pitch ratio equal to the ratio between the minimum distance (equal to 23.7 mm in this case) between two consecutive first main lateral cuts 81 in the circumferential direction and the maximum distance (equal to 33.9 mm in this case) between two consecutive first main lateral cuts 81 in the circumferential direction. Also, R2 can be defined as a pitch ratio equal to the ratio between the minimum distance (equal to 14.6 mm in this case) between two consecutive second main lateral cuts 82 in the circumferential direction and the maximum distance (equal to 20.9 mm in this case) between two consecutive second main lateral cuts 82 in the circumferential direction. Finally, R63 and R64 can be defined as pitch ratios equal to the ratio between the minimum distance (equal to 18.5 mm in this case) between two consecutive main lateral cuts 73 and 74 in the circumferential direction of each of the central ribs 63 and 64 and the maximum distance (equal to 20.9 mm in this case) between two consecutive main lateral cuts 73 and 74 in the circumferential direction of each of the central ribs 63 and 64. In this case, R1 = R2 = R63 = R64 = 0.70.

[0102] This makes it possible to define an overlap level T1,63=T1,64=[(N1 / R1)-(M63×R63)] / [(M63 / R63)-(N1×R1)]=[(N1 / R1)-(M64×R64)] / [(M64 / R64)-(N1×R1)] between the first axial side portion P1 and each central rib 63, 64. This also makes it possible to define an overlap level T63,2=T64,2=[(M63 / R63)-(N2×R2)] / [(N2 / R2)-(M63×R63)]=[(M64 / R64)-(N2×R2)] / [(N2 / R2)-(M64×R64)] between the second axial side portion P2 and each central rib 63, 64.

[0103] This also makes it possible to define an overall pitch ratio Rpg=[Min(N1×R1; N2×R2; M63×R63; M64×R64) / Max(N1 / R1; N2 / R2; M63 / R63; M64 / R64)]^(0.5), where Min(N1×R1; N2×R2; M63×R63; M64×R64) is the relationship between the number of main transverse cuts in the first and second axially outer parts P1, P2 and each central rib 63, 64 and the pitch ratio. M63 / R63; M64 / R64) is the minimum value of the product, in this case the product of the number N1 of the main transverse cuts 81 of the first axially outer part P1 and the pitch ratio R1, and Max(N1 / R1; N2 / R2; M63 / R63; M64 / R64) is the maximum value of the ratio between the number of main transverse cuts of the first and second axially outer parts P1, P2 and each central rib 63, 64 and the pitch ratio, in this case the ratio between the number N2 of the main transverse cuts of the second axially outer part P2 and the pitch ratio R2.

[0104] T1,63, T1,64, T63,2, and T64,2 satisfy, on the one hand, 0.40≦T1,63=T1,64≦0.60, on the other hand, 0.40≦T63,2=T64,2≦0.60, and finally, 0.50≦Rpg≦0.60. In this example, T1,63=T1,64=0.48, T63,2=T64,2=0.49, and Rpg=0.55.

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

[0106] Each of the main transverse cuts 71, 72, 73, 74 and 75 formed in each of the central ribs 61, 62, 63, 64 and 65 respectively opens into each of the first and second circumferential cuts that axially separate the central ribs 61, 62, 63, 64 and 65 in first and second opening zones 711, 712, 721, 722, 731, 732, 741, 742, 751, 752, respectively.

[0107] As an example, considering the first and second circumferentially adjacent major transverse cuts 75A, 75B formed in the central rib 65, the azimuth angle AZ1 of the first major transverse cut 75A relative to a point in the first opening zone 751 is substantially circumferentially aligned with the azimuth angle AZ2 of the second major transverse cut 75B relative to a point in the second opening zone 752. This circumferential alignment feature is replicated by the cuts 71, 72, 73 and 74 formed in each of the central ribs 61, 62, 63 and 64, respectively.

[0108] The main transverse cuts 81, 82 and 71-75 and the main circumferential cuts 51-56 define a plurality of blocks having chamfers on each of the circumferential edges and on each of the transverse edges.

[0109] 2 and 3 respectively show first major transverse cuts 81 and major transverse cuts 75. First major transverse cuts 81 are all identical to one another and, subject to scaling factors, to second major transverse cuts 82. Major transverse cut 75 is identical to major transverse cuts 71, 72, 73, and 74, subject to scaling factors.

[0110] 2, at least 50%, preferably at least 75%, of the first main transverse cuts 81, in this case, each first main transverse cut 81 has a radially inner portion 81i, a radially central portion 81m, and a radially outer portion 81e. The radially inner portion 81i is located radially inward of the radially central portion 81m. The radially outer portion 81e is located radially outward of the radially central portion 81m. The radially inner portion 81i is the radially innermost portion of the first main transverse cut 81, and the radially outer portion 81e is the radially outermost portion of the first main transverse cut 81. The radially central portion 81m extends radially over a height H2 equal to 50% of the height H81 of the first main transverse cut 81. Each radially inner portion 81i and each radially outer portion 81e extends radially over a height H1, H3, respectively, which is equal to 25% of the height H81 of the first main transverse cut 81.

[0111] The radially inner portion 81i has a maximum width Lmax1 that is strictly greater than the maximum width Lmax3 of the radially outer portion. At the cross section II-II', each first main transverse cut 81 has a minimum width Lmin81, which in this case is equal to 0.30 mm. The same is true for the second main transverse cut 82. In this case, Lmax1=1.16, Lmax3=1.00 mm.

[0112] At least 50%, preferably at least 75%, of the first main transverse cuts 81, in this case each first main transverse cut 81, have a width of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less, in at least one zone 90. In the example shown in Figure 2, at least 50%, preferably 75%, of the first main transverse cuts 81, in this case each first main transverse cut 81, have a width of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less over at least 10% of its height H81 (represented in this case by height portion H4) and along at least 10% of its length. At least 50%, preferably at least 75%, of the first main transverse cuts 81, in this case each first main transverse cut 81, have a zone 90 at least partially, in this case completely, located in the radial center 81m. The zone 90 extends over a continuous surface that corresponds to at least 10%, at most 80%, preferably at most 50% of the surface of each front face 81a and rear face 81f of each first major transverse cut 81.

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

[0114] 3, each main transverse cut 75 has a width that varies radially within the main transverse cut 75. At least 50%, preferably at least 75%, of each main transverse cut 75, in this case each main transverse cut 75, has a radially inner portion 75i, a radially central portion 75m, and a radially outer portion 75e. The radially inner portion 75i is located radially inward of the radially central portion 75m. The radially outer portion 75e is located radially outward of the radially central portion 75m. The radially inner portion 75i is the radially innermost portion of the main transverse cut 75, and the radially outer portion 75e is the radially outermost portion of the main transverse cut 75. The radially central portion 75m extends radially over a height H2′ equal to 50% of the height H75 of the main transverse cut 76. Each radially inner portion 75i and each radially outer portion 75e extends radially over a height H1', ​​H3', respectively, equal to 25% of the height H75 of the main transverse cut 75.

[0115] At least 50%, preferably at least 75%, of the major transverse cuts 75, in this case each major transverse cut 75, have a width of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less, in at least one zone 92. In the example shown in Figure 3, at least 50%, preferably 75%, of the major transverse cuts 75, in this case each major transverse cut 75, have a width of 0.50 mm or less, preferably 0.40 mm or less, more preferably 0.35 mm or less over at least 10% of its height H (represented in this case by height portion H4') and along at least 10% of its length.

[0116] The zone 92 extends over a continuous surface representing at least 10%, preferably at least 20%, up to 80%, preferably at least 50% of the surface of each front face 75a and rear face 75f of each major transverse cut 75.

[0117] In the cross section III-III', each main transverse incision 75 has a minimum width Lmin75, which in this case is equal to 0.24 mm. At least 50%, preferably at least 75%, of the main transverse incisions 75, in this case the zone 92 of each main transverse incision 75, is at least partially, in this case completely, located in the radial center 75m. The same applies to the main transverse incisions 71, 72, 73, 74.

[0118] Comparative Test

[0119] Wear measurement

[0120] The tire 10 described above was compared with a control tire T, the tread of which is illustrated in Figure 4. The treads of tire 10 and control tire T are made of the same material. Unlike tire 10, control tire T has N1 = N2, and there are no zones in which the width of the main transverse cuts formed on each axial side is less than 0.50 mm. Specifically, the main transverse cuts formed on each axial side have widths equal to 1.0 mm, 1.2 mm, and 1.5 mm, depending on the cut.

[0121] Each time, four tires 10 and T were driven on a single vehicle, and the wear of the tire mounted on the front of the vehicle was measured as a function of the total distance driven (approximately 15,000 km). To shorten the test, the wear was then extrapolated until one of the tread portions reached the maximum wear indicated by the regulated wear indicator. The average value of the two tires mounted on the front of the vehicle was then calculated.

[0122] The maximum total mileage reached by each tire (which reflects the tire's service life) was compared with the mass loss experienced by each tire when this maximum total mileage was reached. The results are summarized in Table 1 below, with tire T being 100.

[0123] [Table 1]

[0124] In contrast to Control Tire T, whose service life is determined by reaching the regulated wear indicator early on the axial side located on the inside of the vehicle, the service life of Tire 10 is determined by reaching the regulated wear indicator later on the axial side located on the inside of the vehicle, approximately simultaneously with reaching the regulated wear indicator on the axial side located on the outside of the vehicle. Thus, the present invention results in more even tread wear and prevents the stiffest part of the tire from reaching its wear limit early. Therefore, the tire of the present invention can cover a longer mileage than Control Tire T.

[0125] This is confirmed by the greater mass loss of tire 10 compared to the mass loss of control tire T. Specifically, tire 10 loses more mass than control tire T before reaching maximum mileage because it wears more evenly across the tread, and while most of control tire T still has a large amount of material to wear, only one portion (in this case, the axial side located on the inside of the vehicle) has worn to the point where it has reached the regulated wear indicator.

[0126] Noise evaluation

[0127] Noise tests were carried out to evaluate cavity, beat and braking noise at speeds below 90 km / h for tire 10, tire T and the particularly quiet reference tire R. These tests were carried out subjectively by drivers and the results are summarized in Table 2 below: - The symbol "=" indicates a noise level substantially equivalent to that of the reference tire R. - The symbol "-" indicates a slight increase in noise compared to the reference tire R. - The symbol "--" indicates a large increase in noise compared to the reference tire R. The "+" sign indicates a slight reduction in noise compared to the reference tire R.

[0128] [Table 2]

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

[0130] The present invention is not limited to the above-described embodiments. [Explanation of symbols]

[0131] 10 Tires 14 Tread 38 Tread surface 41 first axial edge of tread surface 42 second axial edge of tread surface 43 Axial outer edge of first axial main circumferential cut 44 Axial outer edge of second axial main circumferential cut 51~56 Main circumferential cutting depth 61~65 Center rib 71-75 Horizontal notches formed on each central rib 75A, 75B First and second main transverse cuts adjacent to each other in the circumferential direction 81 First transverse cut formed in first axial side portion 82 a second transverse cut formed in the second axial side portion 711,721,731,741,751 First Aperture Zone 712,722,732,742,752 Second Opening Zone AZ1 Azimuth angle of the first main transverse cut with respect to the point of the first opening zone AZ2 Azimuth angle of the second main transverse cut with respect to the point of the second opening zone EXT Outer side of tire INT: Inside side of tire J: Joint between two circumferentially adjacent patterns M Median plane of tire P0 Axial center (of tread) P1 First axial side P2 Second axial side X Circumferential direction of the tire Y Axial direction of the tire Z radial direction of the tire

Claims

1. A tire (10) comprising a tread (14) intended to come into contact with the ground during travel via a tread surface (38), said tread (14) comprising: main circumferential cuts (51, 52, 53, 54, 55, 56) having a depth of 50% or more of a tread pattern height (Hs), the main circumferential cuts comprising first and second axially outer main circumferential cuts (51, 52) arranged on both axial sides of a median plane (M) of the tire (10), the first and second axially outer main circumferential cuts (51, 52) being the axially outermost main circumferential cuts of the tread (14); a first axial side portion (P1) disposed axially outward of the first axially outer main circumferential notch (51) and extending axially from a first axial edge (41) of the tread surface (38) to an axially outer edge (43) of the first axially outer main circumferential notch (51); a second axial side portion (P2) disposed axially outward of the second axially outer main circumferential notch (52) and extending axially from a second axial edge (42) of the tread surface (38) to an axially outer edge (44) of the second axially outer main circumferential notch (52); Equipped with the first axial side (P1) comprises a first transverse incision (81) N1 formed in the first axial side (P1); the second axial side (P2) comprises N2 second transverse incisions (82) formed in the second axial side (P2), where N2>N1; each of the first and second lateral cuts (81, 82) is called a main lateral cut, and extends over an axial width of at least 50% of the axial width of each of the first and second axial sides, respectively, and has a depth of at least 50% of the tread pattern height (Hs) of the tire (10); at least 50% of said first major transverse cuts (81) and at least 50% of said second major transverse cuts (82) have a width of 0.50 mm or less in at least one zone (90); the tire comprises central ribs i (61, 62, 63, 64, 65), k≧1, separated by first and second axially adjacent main circumferential cuts (51, 52, 53, 54, 55, 56), the or each central rib i (61, 62, 63, 64, 65) comprising transverse cuts (71, 72, 73, 74, 75) Mi>1 formed in the central rib i (61, 62, 63, 64, 65), each of the transverse cuts (71, 72, 73, 74, 75) formed in the central rib i, called a main transverse cut, extending over an axial width of the central rib i equal to or greater than 50% and having a depth equal to or greater than 50% of the tread pattern height (Hs) of the tire (10); the presence of at least one central rib j (63, 64) with Mj>1 major transverse cuts (73, 74) formed in said central rib j such that N1<Mj<N2; A tire (10) characterized by:

2. 2. The tire (10) according to claim 1, wherein at least 75% of the first main transverse incisions (81) and at least 75% of the second main transverse incisions (82), preferably each of the first main transverse incisions (81) and each of the second main transverse incisions (82), have a width of 0.35 mm or less in at least one zone (90).

3. 3. A tyre (10) according to claim 1 or 2, wherein said zone (90) extends for at least 50% of said first main transverse incisions (81) and at least 50% of said second main transverse incisions (82), over at least 10% of their height and along at least 10% of their length.

4. Each of the first and second main transverse cuts (81, 82) has a radially central portion (81m), a radially outer portion (81e) arranged radially outward of the radially central portion (81m), and a radially inner portion (81i) arranged radially inward of the radially central portion (81m), the radially central portion (81m) extending radially over a height (H2) equal to 50% of the height (H) of the first and second main transverse cuts (81, 82), and each of the radially inner portions (81i) and each of the radially outer portions (81e) are arranged radially inward of the first and second main transverse cuts (81, 82).

4. The tyre (10) according to claim 1, wherein the zones (90) of at least 50% of the first main transverse incisions (81) and at least 50% of the second main transverse incisions (82), preferably at least 75% of the first main transverse incisions (81) and at least 75% of the second main transverse incisions (82), more preferably of each of the first and second main transverse incisions (81, 82), are at least partially located in the central portion (81m).

5. At least 50% of the first main transverse cuts (81) and at least 50% of the second main transverse cuts (82), preferably at least 75% of the first main transverse cuts (81) and at least 75% of the second main transverse cuts (82), more preferably each of the first and second main transverse cuts (81, 82) has a radially inner part (81i) and a radially outer part (81e) arranged radially outward of the radially inner part (81i).

5. A tyre (10) according to any one of claims 1 to 4, wherein the radially inner part (81i) is the radially innermost of the first and second main transverse cuts (81, 82) and the radially outer part (81e) is the outermost of the first and second main transverse cuts (81, 82), the radially inner part (81i) having a maximum width (Lmax1) strictly greater than the maximum width (Lmax3) of the radially outer part (81e).

6. 6. The tire (10) according to claim 1, wherein each of the first and second main transverse incisions (81, 82) extends axially from each of the first and second axial edges (41, 42) of the tread surface (38) until it opens into each of the first and second axially outer main circumferential incisions (51, 52).

7. 7. Tyre (10) according to any one of claims 1 to 6, wherein N2 / N1 > 1.30, preferably N2 / N1 > 1.

50.

8. 8. A tire (10) according to any one of claims 1 to 7, wherein each of the main transverse cuts (71, 72, 73, 74, 75) formed in each of the central ribs i extends axially from each of the first main circumferential cuts (51, 52, 53, 54, 55, 56) until it opens into each of the second main circumferential cuts (51, 52, 53, 54, 55, 56).

9. 9. The tire (10) according to claim 1, wherein each of the central ribs i (61, 62, 65) other than the central rib j (63, 64) comprises a main transverse cut (71, 72, 75) with Mm > 1, the main transverse cut (71, 72, 75) being formed in the central rib i (61, 62, 65) other than the central rib j (63, 64), extending over an axial width of the central rib i (61, 62, 65) other than the central rib j (63, 64) that is 50% or more of the axial width of the central rib i (61, 62, 65) other than the central rib j (63, 64), and having a depth of the tread pattern height (Hs) of the tire (10) that is 50% or more, and wherein for each of the central ribs i (61, 62, 65) other than the central rib j (63, 64), N1 ≦ Mm ≦ Mj < N2 or N1 < Mj ≦ Mm ≦ N2.

10. 10. Tyre (10) according to any one of claims 1 to 9, wherein N2 / Mj ≥ 1.15 and Mj / N1 ≥ 1.15, preferably N2 / Mj ≥ 1.25 and Mj / N1 ≥ 1.

25.

11. N1, N2 and Mj are 0.40≦[(N1 / R1)-(Mj×Rj)] / [(Mj / Rj)-(N1×R1)]≦0.60, 0.40≦[(Mj / Rj)-(N2×R2)] / [(N2 / R2)-(Mj×Rj)]≦0.60, where -R1 is the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive first main transverse cuts (81) and the maximum distance between two circumferentially consecutive first main transverse cuts (81); -R2 is the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive second major transverse cuts (82) and the maximum distance between two circumferentially consecutive second major transverse cuts (82); Tyre (10) according to any one of claims 1 to 10, wherein -Rj is a pitch ratio equal to the ratio between the smallest distance between two circumferentially consecutive main transverse incisions (71, 72, 73, 74, 75) of the or each central rib j (61, 62, 63, 64, 65) and the largest distance between two circumferentially consecutive main transverse incisions (71, 72, 73, 74, 75) of the or each central rib j.

12. N1, N2, and Mj are in the range of 0.50≦[Min(N1×R1; N2×R2; Mj×Rj) / Max(N1 / R1; N2 / R2; Mj / Rj)]^(0.5)≦0.60, -R1 is the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive first main transverse cuts (81) and the maximum distance between two circumferentially consecutive first main transverse cuts (81); -R2 is the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive second major transverse cuts (82) and the maximum distance between two circumferentially consecutive second major transverse cuts (82); -Rj is the pitch ratio equal to the ratio between the minimum distance between two circumferentially consecutive main transverse cuts (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 main transverse cuts (71, 72, 73, 74, 75) of the or each central rib j; -Min(N1*R1; N2*R2; Mj*Rj) is the minimum value for the product of the number and pitch ratio of the main transverse incisions (81, 82, 71, 72, 73, 74, 75) of said first and second axially outer portions (P1, P2) and of the or each central rib j (61, 62, 63, 64, 65), -Max(N1 / R1; N2 / R2; Mj / Rj) is the maximum value for the ratio between the number of main transverse incisions (81, 82, 71, 72, 73, 74, 75) of said first and second axially outer portions (P1, P2) and of the or each central rib j (61, 62, 63, 64, 65) and the pitch ratio.

13. 13. A tyre (10) according to any one of claims 1 to 12, wherein at least 50%, preferably at least 75%, more preferably each of the main transverse cuts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65) have a width of 0.50 mm or less in at least one zone (92).

14. 14. A tyre (10) according to claim 13, wherein said zone (92) extends over at least 50%, preferably at least 75%, more preferably for each of said main transverse cuts (71, 72, 73, 74, 75) formed in said or central rib i (61, 62, 63, 64, 65) over at least 10% of its height and along at least 10% of its length.

15. Each of the main transverse notches (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65) has a radially central portion (75m), a radially outer portion (75e) arranged radially outward of the radially central portion, and a radially inner portion (75i) arranged radially inward of the radially central portion (75m), the radially central portion (75m) extending radially over a height equal to 50% of the height of the main transverse notch (71, 72, 73, 74, 75), and each of the radially inner and outer portions (75i, 75e) extending radially over a height equal to 25% of the height of the main transverse notch (71, 72, 73, 74, 75).

15. A tyre (10) according to claim 13 or 14, wherein the zones (92) of at least 50% of the main transverse cuts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65), preferably at least 75% of the main transverse cuts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65), more preferably of each of the main transverse cuts (71, 72, 73, 74, 75) formed in the or each central rib i (61, 62, 63, 64, 65) are at least partially located in the central portion (75m).

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