Tire comprising a tread with uniform wear and reduced noise

Abstract

The invention relates to a tyre (10), said tyre (10) comprising N1lt; n2 first and second main transverse cutouts (81, 82) provided in the axial side portions (P1, P2) extending over an axial width greater than or equal to 50% of the axial width of each of the first and second axial side portions (P1, P2), respectively, and has a depth greater than or equal to 50% of the height of the tread pattern of the tire (10). In at least one region, the width of at least 50% of the first main transverse cut-outs (81) and at least 50% of the second main transverse cut-outs (82) is less than or equal to 0.50 mm. At least one central rib j (63, 64) is present, said central rib j (63, 64) comprising Mjgt; one main lateral cutout (73, 74), which is provided in the central rib section (j), and which satisfies N1lt; mjlt; n2.

Description

Technical Field

[0001] The present invention relates to a tire for passenger vehicles. By tire is understood a carcass intended to form, by cooperating with a supporting element, such as a rim, a cavity capable of being pressurized to a pressure higher than atmospheric pressure. The tire according to the invention has a structure of a generally annular shape presenting rotational symmetry about a main axis of the tire. Background Art

[0002] It is known in the prior art that Brand name PRIMACY Passenger vehicle tires sold in series. Such tires include a tread intended to come into contact with the ground via the tread surface when the tire is running.

[0003] The tread includes a main circumferential incision, the depth of which is greater than or equal to 50% of the tread pattern height and includes a first axially outer main circumferential incision and a second axially outer main circumferential incision arranged axially on both sides of the tire midplane. The first axially outer main circumferential incision and the second axially outer main circumferential incision are the axially outermost main circumferential incisions of the tread.

[0004] The tread comprises a first axial side portion axially arranged outside the first axially outer main circumferential cutout and a second axial side portion axially arranged outside the second axially outer main circumferential cutout. The tread also comprises a transverse cutout formed at least partially in each of the first and second axial side portions.

[0005] Despite having excellent performance aspects, this prior art tire exhibits uneven wear. In particular, depending on the vehicle on which the tire is mounted, one of the first axial side portion and the second axial side portion is found to wear faster than the other. When the wear causes the tread to reach a specified wear threshold, it is necessary to replace the tire, although other parts of the tire still have a large amount of material that can be worn away.

[0006] It is therefore an object of the present invention to extend the service life of a tire by reducing uneven wear of the tread between a first axial side portion and a second axial side portion. Summary of the invention

[0007] To this end, the invention relates to a tire comprising a tread intended to come into contact with the ground via a tread surface when the tire is running, said tread comprising:

[0008] - main circumferential incisions, the depth of which is greater than or equal to 50% of the tread pattern height and comprising a first axially outer main circumferential incision and a second axially outer main circumferential incision arranged axially on both sides of the tire midplane, the first axially outer main circumferential incision and the second axially outer main circumferential incision being the axially outermost main circumferential incisions of the tread,

[0009] a first axial side portion arranged axially on the outside of the first axially outer main circumferential cutout and extending axially from a first axial edge of the tread surface to an axially outer edge of the first axially outer main circumferential cutout,

[0010] a second axial side portion arranged axially on the outside of the second axially outer main circumferential cutout and extending axially from the second axial edge of the tread surface to the axially outer edge of the second axially outer main circumferential cutout,

[0011] The first axial side portion comprises N1 first transverse cutouts formed in the first axial side portion,

[0012] The second axial side portion includes N2 second transverse cutouts formed in the second axial side portion, wherein N2>N1,

[0013] each first and second transverse incision, referred to as main transverse incisions, extends over an axial width greater than or equal to 50% of the axial width of each first and second axial side portion, respectively, and has a depth greater than or equal to 50% of the tread height of the tyre,

[0014] In at least one region, at least 50% of the first main transverse cuts and at least 50% of the second main transverse cuts have a width less than or equal to 0.50 mm,

[0015] The tyre comprises k≥1 central ribs i, said central ribs i being axially delimited by first and second axially adjacent main circumferential cuts, said central ribs i or each central rib i comprising Mi>1 transverse cuts formed in said central ribs i, each transverse cut formed in said central ribs i (referred to as main transverse cuts) extending over an axial width greater than or equal to 50% of the axial width of said central ribs i and having a depth greater than or equal to 50% of the tread height of the tyre,

[0016] Wherein, in the tire, there is at least one central rib j, the central rib j includes Mj>1 main transverse cuts formed in the central rib j, and satisfies N1 <Mj<N2。

[0017] The present invention can extend the service life of the tire by making the tread wear more uniform between the first axial side portion and the second axial side portion while reducing the noise generated by the tread.

[0018] In particular, the inventors of the present invention have found that the hardest part of the tread is the part that wears the fastest, namely because the engine torque passes through the hardest part of the tread. When there is a significant difference in hardness between the two parts of the tread, as in the case of the above-mentioned prior art tire, uneven wear is observed, resulting in a shorter service life. In the case of the prior art tire, the difference in hardness is explained by the larger number N2 of second main transverse cuts formed in the second axial side part compared to the smaller number N1 of first main transverse cuts formed in the first axial side part. In particular, due to the relatively large number of second cuts, the hardness of the second axial side part is lower than that of the first axial side part.

[0019] In order to reduce or even eliminate this more rapid wear of the first axial side portion, the inventors have the idea of ​​masking the lower hardness of the second axial side portion by creating at least one zone (a zone with a width less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm) between the leading and trailing faces of a large number (at least 50%) of the second main transverse cuts to prevent the relative movement of the blocks separated by the second main transverse cuts when the tire is running. In particular, due to this zone, it is easier to fix the blocks carrying the leading and trailing faces when the tire is running, which has the effect of making this second axial side portion harder. In the same way, the blocks separated by the first main transverse cuts are also fixed. Therefore, independently of the number of cuts in the first and second axial side portions, each of these first and second axial side portions is hardened in a similar way, so that there is uniform wear between the first and second axial side portions.

[0020] The inventors have determined the value of 0.50 mm as the value below which contact between the leading and trailing faces is observed under 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 contact each other, but this is under extreme driving conditions that do not reflect normal use of the tire.

[0021] The area with a width of less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm, may be reduced to two points on the leading and trailing surfaces, the two points being at a distance of less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm from each other, or may extend over a surface that is not reduced to two points on the leading and trailing surfaces. In the case of such a surface that is not reduced to two points on the leading and trailing surfaces, a plurality of points on each leading and trailing surface are spaced in pairs at a distance of less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm from each other.

[0022] The feature of N2 / N1>1 can particularly reduce the noise generated by the tire. Specifically, each axial portion of the tread generates noise, and its harmonics are concentrated at frequencies that particularly depend on the number and distribution of the lateral incisions formed in this axial portion of the tread. To reduce the noise generated by the tire, the inventors found that it is effective to disperse the frequencies of the harmonics of the different axial portions of the tread and thus disperse the sound energy generated by the tire. To disperse these frequencies, the tire according to the present invention satisfies that the first axial side portion and the second axial side portion have different numbers of main lateral incisions, so as to be able to distinguish the harmonics associated with each first axial side portion and the second axial side portion, and thus reduce the noise generated by the tire. Similarly, by the feature of N1<Mj<N2, the central rib portion j formed with Mj main lateral incisions can disperse the sound energy generated by the tire, and thus reduce the noise generated by the tire.

[0023] Generally, the tread surface is axially bounded by a first axial edge and a second axial edge. The first axial edge and the second axial edge of the tread surface are determined on a tire mounted on a nominal rim and inflated to a nominal pressure according to the 2021 European Tyre and Rim Technical Organization (or "ETRTO") standard. The first axial edge and the second axial edge of the tread surface are arranged on both sides of the tire median plane and are formed by lines substantially parallel to the circumferential direction of the tire. If there is an obvious boundary between the tread surface and the rest of the tire, the first axial edge and the second axial edge of the tread surface are simply determined. If the tread surface is continuous with the outer surface of the tire sidewall, the first axial edge and the second axial edge can be determined, for example, by considering the following: in each meridian cross-section plane, the first axial edge and the second axial edge each pass through such a point at which the angle between the tangent to the tread surface and the straight line parallel to the axial direction and passing through this point is equal to 30°. When there are multiple points in the meridian cross-section plane at which the absolute value of the angle is equal to 30°, the radially outermost point is used.

[0024] Of course, the said first axial side portion and the second axial side portion of the tread or each first axial side portion and each second axial side portion may include other lateral incisions in addition to the first main lateral incision and the second main lateral incision. The said first axial side portion and the second axial side portion of the tread or each first axial side portion and each second axial side portion may also include other incisions in addition to the main lateral incisions or non-main lateral incisions, such as circumferential incisions.

[0025] The incision (or the portion of the incision) has two main characteristic dimensions on the tread surface: a width and a curvilinear length, which satisfies that the curvilinear length is at least equal to twice the width. Thus, the incision is delimited by at least two main sides that determine its curvilinear length and are connected by a bottom, the two main sides being spaced apart from each other by a non-zero distance (called the incision width).

[0026] On a new tire, the width of the cut is the maximum distance between the two main side faces, measured by default at the radial dimension coinciding with the tread surface when the cut has no chamfers, and by default at the radially outermost radial dimension of the cut radially inside the chamfers when the cut has chamfers. The width is measured substantially perpendicular to the main side faces. If a width other than the default width is specified (e.g. a width at a specific dimension), the width is equal to the minimum distance between the two main side faces at the specific dimension of the cut.

[0027] On a new tire, the depth of the cut is the maximum radial distance between the bottom of the cut and the projection of the bottom of the cut on the ground when the tire is running. The maximum value of the depth of the cut is called the tread height.

[0028] The incisions may be transverse or circumferential.

[0029] The transverse incision satisfies that the incision extends in an average direction that forms an angle strictly greater than 30°, preferably greater than or equal to 45° with the circumferential direction of the tire (i.e., an angle less than or equal to 60°, preferably strictly less than 45°, with the axial direction of the tire). The average direction is the shortest curve connecting the two ends of the incision and parallel to the tread surface. The transverse incision can be continuous, i.e., not interrupted by a tread block or another incision, so that the two main sides that determine its length are not interrupted along the length of the transverse incision. The transverse incision can also be discontinuous, i.e., interrupted by one or more tread blocks and / or one or more incisions, so that the two main sides that determine its length are interrupted by one or more tread blocks and / or one or more incisions.

[0030] A circumferential incision satisfies that the incision extends in an average 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 average direction is the shortest curve connecting the two ends of the incision and parallel to the tread surface. In the case of a continuous circumferential incision, the two ends coincide with each other and are connected by a curve forming a complete circumference around the tire. The circumferential incision can be continuous, i.e. not interrupted by a tread block or another incision, so that the two main sides that determine its length are not interrupted over the entire circumference around the tire. The circumferential incision can also be discontinuous, i.e. interrupted by one or more tread blocks and / or one or more incisions, so that the two main sides that determine its length are interrupted over the entire circumference around the tire by one or more tread blocks and / or one or more incisions.

[0031] In the case of a transverse cut, the side faces are referred to as leading and trailing faces and are each provided with a leading edge and a trailing edge, respectively, the leading edge being the edge entering the contact patch before the edge of the trailing edge for a given circumferential line.

[0032] In an embodiment that optionally improves braking on dry ground, the or each transverse cut has a chamfer. The chamfer of the transverse cut may be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a plane inclined relative to the leading or trailing face, the plane continuing the leading or trailing face up to the leading edge or trailing edge that circumferentially delimits the transverse cut. A rounded chamfer is formed by a curved surface tangentially merged with the leading or trailing face, the curved surface continuing the leading or trailing face. The chamfer of the transverse cut is characterized by a height and a width that are respectively equal to the radial distance and the distance in a direction perpendicular to the leading or trailing face between the common point shared by the leading or trailing face to which the chamfer continues and the leading or trailing edge that circumferentially delimits the transverse cut.

[0033] In certain embodiments that optionally improve braking on wet surfaces and lateral grip on dry surfaces, at least one main circumferential cut has a chamfer. The chamfer of the circumferential cut can be a straight chamfer or a rounded chamfer. The straight chamfer is formed by a plane inclined relative to the axial inner face and the axial outer face, the plane continuing the axial inner face and the axial outer face until the axial inner edge or the axial outer edge that axially defines the circumferential cut. The rounded chamfer is formed by a curved surface that merges tangent to the axial inner face or the axial outer face, the curved surface continuing the axial inner face or the axial outer face. The chamfer of the circumferential cut is characterized in that the height and width are respectively equal to the radial distance and the axial distance between the common point shared by the axial inner face or the axial outer face to which the chamfer continues and the axial inner edge or the axial outer edge that axially defines the circumferential cut.

[0034] The tyre according to the invention has a generally annular shape about an axis of rotation substantially coinciding with the axis of rotation of the tyre. This axis of rotation defines three directions commonly used by those skilled in the art: an axial direction, a circumferential direction and a radial direction.

[0035] The expression "axial direction" means a direction substantially parallel to the axis of rotation of the tyre, ie the axis of rotation of the tyre.

[0036] The expression “circumferential direction” means a direction substantially perpendicular simultaneously to the axial direction and to the radius of the tire (in other words tangential to a circle centered on the axis of rotation of the tire) in each meridian plane.

[0037] The expression “radial direction” means a direction along a radius of the tire, ie any direction intersecting the axis of rotation of the tire and being substantially perpendicular to this axis.

[0038] The expression “median plane of the tire” (indicated by M) means the plane perpendicular to the axis of rotation of the tire and situated axially centred between the two beads and passing through the axial middle of the crown reinforcement.

[0039] The expression "equatorial circumferential plane of the tire" means a plane passing through the equator of the tire and perpendicular to the median plane and to the radial direction in a meridian section plane. In a meridian section plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), the equator of the tire is the axis parallel to the axis of rotation of the tire and situated equidistantly 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, such as a rim.

[0040] The expression “meridian plane” means a plane parallel to and containing the axis of rotation of the tyre and perpendicular to the circumferential direction.

[0041] The expressions “radially inside / radially inboard” and “radially outside / radially outboard” mean, respectively, closer to and further away from the axis of rotation of the tire. The expressions “axially inside / axially inboard” and “axially outside / axially outboard” mean, respectively, closer to and further away from the mid-plane of the tire.

[0042] The term "bead" means the portion of the tyre intended to attach the tyre to a mounting support, such as a wheel comprising a rim. Thus, each bead is particularly intended to come into contact with a flange of the rim so that it can be attached.

[0043] Any numerical interval expressed by the expression "between a and b" represents a numerical range extending from greater than a to less than b (i.e., excluding the limits a and b), while any numerical interval expressed by the expression "a to b" means a numerical range extending from a to b (i.e., including the strict limits a and b).

[0044] In a preferred embodiment of the invention, the tire is intended for passenger vehicles as defined according to the European Tyre and Rim Technical Organization or "ETRTO" standard of 2021. Such a tire has a cross section in a meridian section plane characterized by a section height H and a nominal section width S within the meaning of the European Tyre and Rim Technical Organization (or "ETRTO") standard of 2021, characterized by a ratio H / S expressed as a percentage at most equal to 90, preferably at most equal to 70 and at least equal to 30, and a nominal section width S 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 diameter D at the flange, 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.

[0045] In a preferred embodiment of the invention, the tire is a "summer" tire. A summer tire is understood to be a tire that is not a "four-season" tire or an "all-season" tire or a "winter" tire.

[0046] Winter tires are marked in particular with the M+S mark (M+S is short for "Mud+Snow") and / or the 3PMSF mark (3PMSF is short for "3 Peaks Mountain Snowflake"). Due to their performance on snow, all-season tires or all-season tires also have the M+S mark and / or the 3PMSF mark. Summer tires therefore do not have the M+S mark or the 3PMSF mark.

[0047] In an embodiment for making the wear between the first axial side portion and the second axial side portion more uniform, in at least one area, at least 75% of the first main transverse cuts and at least 75% of the second main transverse cuts, preferably each first main transverse cut and each second main transverse cut, have a width less than or equal to 0.35 mm.

[0048] Optionally and preferably, in at least one region, at least 50% of the first main transverse cuts and at least 50% of the second main transverse cuts have a width less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm. By reducing the width of the region, contact of the leading and trailing surfaces is facilitated.

[0049] Optionally and preferably, in at least one area, at least 75% of the first main transverse cuts and at least 75% of the second main transverse cuts, preferably each first main transverse cut and each second main transverse cut has a width less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm.

[0050] Optionally and preferably, the region extends over at least 10% of the height of at least 50% of the first main transverse cutout and at least 50% of the second main transverse cutout and along at least 10% of the length. By increasing the height and length along which the blocks can contact each other, contact of the leading and trailing faces is facilitated.

[0051] Optionally and preferably, the region extends over a continuous surface of at least 10%, preferably at least 20%, of the surface of each leading and trailing face of at least 50% of the first main transverse cutout and at least 50% of the second main transverse cutout. Thus, due to the continuous surface, the ability of the leading and trailing faces to make point contact relative to point contact is maximized.

[0052] Advantageously, said zone extends over a continuous surface of at most 80%, preferably at most 50%, of the surface of each leading edge face and trailing edge face of at least 50% of the first main transverse cutout and at least 50% of the second main transverse cutout.

[0053] Even more preferably, said area extends over a continuous surface of at least 10%, preferably at least 20% and at most 80%, preferably at most 50%, of the surface of each leading edge face and trailing edge face of at least 75% of the first main transverse cut (very preferably each first main transverse cut) and at least 75% of the second main transverse cut (very preferably each second main transverse cut).

[0054] In a preferred and optional embodiment, each first main transverse cut and the second main transverse cut has a radial middle part, a radial outer part and a radial inner part, the radial outer part is radially arranged on the outside of the radial middle part, the radial inner part is radially arranged on the inside of the radial middle part, the radial middle part extends radially at a height equal to 50% of the height of the first main transverse cut and the second main transverse cut, each radial inner part and radial outer part extends radially at a height equal to 25% of the height of the first main transverse cut and the second main transverse cut, and 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, and more preferably the area of ​​each first main transverse cut and the second main transverse cut is at least partially located in the middle part.

[0055] This ensures that contact between the leading edge surface and the trailing edge surface occurs in the middle portion. Therefore, this allows the first main cutout and the second main cutout to have a relatively large width in other portions (particularly in the radially outer portion), thereby increasing the area-to-void ratio.

[0056] In certain embodiments, at least 50% of the first main transverse cuts and at least 50% of the second main transverse cuts, preferably at least 75% of the first main transverse cuts and at least 75% of the second main transverse cuts, more preferably each of the first main transverse cuts and the second main transverse cuts 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 the first main transverse cuts and the second main transverse cuts, the radially outer portion being the outermost portion of the first main transverse cuts and the second main transverse cuts, the maximum width of the radially inner portion being strictly greater than the maximum width of the radially outer portion. By using a main transverse cut having a radially variable maximum width, the occurrence of chipping of the block portion is minimized, particularly in the second axial side portion.

[0057] In an advantageous but optional embodiment, the tire has an inner side and an outer side defined when the tire is mounted on a vehicle, the first axial side portion being arranged on the same side of the median plane as the outer side, and the second axial side portion being arranged on the same side of the median plane as the inner side.

[0058] The expression "inside and outside specified when the tire is mounted on a vehicle" means that the tire is designed so that one side thereof is arranged on the inside and the other side thereof is arranged on the outside. This orientation specified by the tire manufacturer ensures that the tire functions as intended. In particular, mounting the tire in an orientation different from that specified by the manufacturer may result in dangerous behavior of the vehicle. The expression "outside" 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 "inside" means the side of the tire that faces the wheel arch of the vehicle on which the tire is mounted. Usually, the tire has a marking indicating the inside and the outside.

[0059] In an advantageous but optional embodiment, each first and second main transverse incision extends axially from each first and second axial edge of the tread surface, respectively, to each first and second axially outer main circumferential incision, respectively, thereby improving the mobility of the blocks of the first and second axial side portions, thereby improving the flattening of the tire and therefore the rolling resistance.

[0060] In other embodiments, it is conceivable that each first main transverse cutout and / or each second main transverse cutout does not open into each first axially outer main circumferential cutout and second axially outer main circumferential cutout adjacent thereto, respectively. In these variants, the main transverse cutouts are referred to as blind cutouts.

[0061] In advantageous embodiments, N2 / N1 ≥ 1.30, and preferably N2 / N1 ≥ 1.50. By further differentiating the number of first main transverse incisions and second main transverse incisions formed in each first axial side portion and each second axial side portion respectively, the noise generated by the tire is even further reduced.

[0062] Advantageously, N2 / N1 ≤ 2.00, and preferably N2 / N1 ≤ 1.75. By overly differentiating the number of first main transverse incisions and second main transverse incisions formed in each first axial side portion and each second axial side portion respectively, a relatively significant difference will be generated between the hardness of the first axial side portion and the hardness of the second axial side portion, which will increase the risk of uneven wear.

[0063] In a preferred variant, the ratio C / N2 ranges from 14 to 20, preferably from 16 to 19. In other preferred variants 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 perimeter value in millimeters when the tire is not mounted and not inflated.

[0064] In an advantageous but optional embodiment, each main transverse incision formed in each central rib portion i extends axially from each first main circumferential incision until it leads to each second main circumferential incision. Thereby, the mobility of the block portion of each central rib portion is improved, thereby improving the flattening of the tire and thus improving the rolling resistance.

[0065] In an optional and advantageous embodiment, each central rib portion i other than the central rib portion j includes Mm > 1 main transverse incisions, which are formed in the central rib portion i other than the central rib portion j, extend over an axial width greater than or equal to 50% of the axial width of the central rib portion i other than the central rib portion j, and have a depth greater than or equal to 50% of the tread pattern height of the tire. Each central rib portion i other than the central rib portion j satisfies N1 ≤ Mm ≤ Mj < N2 or N1 < Mj ≤ Mm ≤ N2. Therefore, the sound energy generated by the tire is further dispersed thereby, and thus the noise generated by the tire is reduced.

[0066] In some variants, Mi = Mm, which means that all the transverse incisions formed in the central rib portion i are main transverse incisions. In other variants, Mi > Mm, which means that a part of the transverse incisions formed in the central rib portion i are not main transverse incisions.

[0067] In an advantageous and optional variant, N2 / Mj≥1.15 and Mj / N1≥1.15, and preferably N2 / Mj≥1.25 and Mj / N1≥1.25. The noise generated by the tire is further reduced by further differentiating the number of Mj main transverse cuts compared to the number of first and second main transverse cuts formed in each first and second axial side portions, respectively.

[0068] Advantageously, N2 / Mj≤1.75 and Mj / N1≤1.75, and preferably N2 / Mj≤1.50 and Mj / N1≤1.50. By excessively differentiating the number of main transverse cuts formed in the central rib j formed with Mj main transverse cuts, a relatively significant difference will be created between the hardness of the first and second axial side portions on the one hand and the hardness of the central rib j formed with Mj main transverse cuts on the other hand, which will increase the risk of uneven wear.

[0069] In a preferred variant, the ratio C / Mj ranges from 18 to 23, preferably from 20 to 23. As previously mentioned, C is the value of the circumference of the tire when it is not mounted and not inflated, expressed in millimeters.

[0070] In a preferred and optional embodiment, N1, N2 and Mj satisfy:

[0071] -0.40≤[(N1 / R1)-(Mj×Rj)] / [(Mj / Rj)-(N1×R1)]≤0.60,

[0072] -0.40≤[(Mj / Rj)-(N2×R2)] / [(N2 / R2)-(Mj×Rj)]≤0.60, and

[0073] in:

[0074] - R1 is a spacing ratio equal to the ratio between the minimum distance between two first circumferentially consecutive main transverse cuts and the maximum distance between two first circumferentially consecutive main transverse cuts,

[0075] - R2 is a spacing ratio equal to the ratio between the minimum distance between two second circumferentially consecutive main transverse cuts and the maximum distance between two second circumferentially consecutive main transverse cuts,

[0076] - Rj is the spacing ratio equal to the ratio between the minimum distance between two circumferentially consecutive main transverse cuts of the or each central rib j and the maximum distance between two circumferentially consecutive main transverse cuts of the or each central rib j.

[0077] In these preferred embodiments, an acoustic overlap level is determined between the first axially outer portion and said central rib j or each central rib j on the one hand, and between the second axially outer portion and said central rib j or each central rib j on the other hand. The lower these overlap levels, the greater the dispersion of the acoustic energy, making it possible to reduce the noise generated by the tire. However, it is preferred that the overlap level is not too small, as this would increase the risk of generating frequency modulation and thus beat noise.

[0078] In a preferred and optional embodiment, N1, N2 and Mj satisfy 0.50≤[Min(N1×R1; N2×R2; Mj×Rj) / Max(N1 / R1; N2 / R2; Mj / Rj)]^(0.5)≤0.60, wherein:

[0079] - R1 is a spacing ratio equal to the ratio between the minimum distance between two first circumferentially consecutive main transverse cuts and the maximum distance between two first circumferentially consecutive main transverse cuts,

[0080] - R2 is a spacing ratio equal to the ratio between the minimum distance between two second circumferentially consecutive main transverse cuts and the maximum distance between two second circumferentially consecutive main transverse cuts,

[0081] - Rj is a spacing ratio equal to the ratio between the minimum distance between two circumferentially consecutive main transverse cuts of the or each central rib j and the maximum distance between two circumferentially consecutive main transverse cuts of the or each central rib j,

[0082] - Min(N1×R1; N2×R2; Mj×Rj) is the minimum value of the product of the number of main transverse cutouts and the ratio of the spacings between the first and second axially outer portions and the or each central rib j,

[0083] - Max(N1 / R1; N2 / R2; Mj / Rj) is the maximum value of the ratio between the number of main transverse cutouts and the ratio of the pitches of the first and second axially outer portions and of the or each central rib j.

[0084] In these preferred embodiments, an overall spacing ratio is determined between the first axially outer portion, the central rib j or each central rib j and the second axially outer portion. The lower this overall spacing ratio, the wider the dispersion of the acoustic energy, which can reduce the noise generated by the tire. However, it is preferred that the overall spacing ratio is not too small, because this will produce too large a difference in hardness and will increase the risk of local wear.

[0085] In a preferred and optional embodiment, in at least one area, at least 50%, preferably at least 75%, more preferably each of the main transverse cuts formed in the central rib i or each central rib i has a width less than or equal to 0.50 mm. In order to mask potential differences in hardness between the central rib i or each central rib i and the first and second axial side portions, the central rib i or each central rib i is hardened in a similar manner so that there is uniformity of wear between the central rib i or each central rib i and the first and second axial side portions.

[0086] Preferably, in at least one area, at least 50%, preferably at least 75%, and more preferably each main transverse cutout formed in the central rib i or each central rib i has a width less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm.

[0087] In a preferred variant, the region extends over at least 50%, preferably at least 75%, more preferably at least 10% of the height and along at least 10% of the length of each main transverse cutout formed in the or each central rib i. By increasing the height and length along which the blocks can contact each other, contact of the leading and trailing faces is facilitated.

[0088] Optionally and preferably, said area extends over a continuous surface of at least 10%, preferably at least 20%, of the surface of each leading and trailing face of at least 50% of the main transverse cuts formed in the or each central rib i. Thus, due to the continuous surface, the ability of the leading and trailing faces to make point contact relative to point contact is maximized.

[0089] Advantageously, said zone extends over a continuous surface of at most 80%, preferably at most 50%, of the surface of each leading and trailing face of at least 50% of the main transverse cutouts formed in the or each central rib i.

[0090] Even more preferably, said area extends over a continuous surface of at least 10%, preferably at least 20% and at most 80%, preferably at most 50%, of the surface of each leading edge face and trailing edge face of at least 75% of the main transverse cuts (very preferably each main transverse cut) formed in said central rib i or each central rib i.

[0091] In a preferred and optional embodiment, each main transverse cut formed in the central rib i or each central rib i has a radial middle part, a radial outer part and a radial inner part, the radial outer part is radially arranged on the outside of the radial middle part, the radial inner part is radially arranged on the inside of the radial middle part, the radial middle part extends radially at a height equal to 50% of the height of the main transverse cut, each radial inner part and radial outer part extends radially at a height equal to 25% of the height of the main transverse cut, and at least 50% of the main transverse cuts formed in the central rib i or each central rib i, preferably at least 75% of the main transverse cuts formed in the central rib i or each central rib i, and more preferably the area of ​​each main transverse cut formed in the central rib i or each central rib i is at least partially located in the middle part.

[0092] In a similar manner to the first and second main transverse cuts, this ensures that contact between the leading edge face and the trailing edge face occurs in the middle portion. Therefore, this allows the main transverse cuts to have a relatively large width in other portions (particularly in the radially outer portion), thereby being able to increase the area-to-void ratio.

[0093] In certain preferred variant forms, there is at least one central rib i, which includes the same number of main transverse cuts as the first axial side portion, and / or there is at least one central rib i, which includes the same number of main transverse cuts as the second axial side portion. These variant forms make it possible to create visual continuity between the first axial side portion and the second axial side portion and a portion of the central rib. Even more preferably, the rib or one rib that includes the same number of main transverse cuts as the first axial side portion is a rib axially adjacent to the first axial side portion, and / or the rib or one rib that includes the same number of main transverse cuts as the second axial side portion is a rib axially adjacent to the second axial side portion.

[0094] In an embodiment for further reducing the noise generated by the tire, each main transverse cut is formed in the central rib i or each central rib i, until it leads to each first circumferential cut and second circumferential cut that axially defines the central rib i in the first open area and the second open area, respectively, and the orientation of the point of the first open area of ​​the first main transverse cut formed in the central rib i is basically aligned with the orientation of the point of the second open area of ​​the second main transverse cut formed in the central rib i in the circumferential direction, and the first main transverse cut and the second main transverse cut formed in the central rib i are adjacent in the circumferential direction.

[0095] The expression "substantially aligned" means being circumferentially distanced from each other by at most 5% of the average distance separating a first circumferentially adjacent main transverse cutout and a second circumferentially adjacent main transverse cutout formed in said central rib i.

[0096] Preferably, the depth of each main circumferential incision is greater than or equal to 75% of the tread pattern height, more preferably greater than or equal to 90% of the tread pattern height.

[0097] In an embodiment of a tire in which the main circumferential cuts are relatively deep and which is suitable for use on passenger vehicles or trucks, the depth of each main circumferential cut ranges 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.

[0098] In an embodiment where the main circumferential cuts are relatively wide main circumferential grooves and are suitable for tires for passenger vehicles or trucks, the axial width of each main circumferential cut is greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, more preferably in the range of 5.0 mm to 13.0 mm.

[0099] In conventional manner, the tyre comprises a crown, two sidewalls and two beads, each sidewall connecting each bead to the crown. Again in conventional manner, the crown comprises a tread and a crown reinforcement arranged radially on the inside of the tread. The tyre also comprises a carcass reinforcement anchored in each bead and extending radially in each sidewall and axially in the crown radially on the inside of the crown reinforcement.

[0100] In conventional manner, the crown reinforcement comprises at least one crown layer comprising reinforcing elements. These reinforcing elements are preferably textile or metal filamentary elements.

[0101] In an embodiment for obtaining the properties of a tyre known as a radial tyre, for example as defined by ETRTO, the carcass reinforcement comprises at least one carcass layer, the or each carcass layer comprising filamentary carcass reinforcing elements, each filamentary carcass reinforcing element extending substantially in a main direction forming an angle with the circumferential direction of the tyre having an absolute value ranging from 80° to 90°. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] The invention will be better understood by reading the following description given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0103] - Figure 1 is a top view of the tread of a tire according to the present invention,

[0104] - Figure 2 for Figure 1Cross-sectional view of the main transverse cut on the midplane II-II',

[0105] - Figure 3 for Figure 1 a cross-sectional view of the main transverse cut on the midplane III-III', and

[0106] - Figure 4 For the control tire Figure 1 A similar view of a tire of FIG. 1 is shown which can demonstrate the advantages of the present invention. DETAILED DESCRIPTION

[0107] Reference frames X, Y, Z are shown, corresponding to the usual axial direction (Y), radial direction (Z) and circumferential direction (X) of the tire, respectively.

[0108] Reference Figure 1 , a tyre according to the invention is indicated by reference numeral 10. The tyre 10 has a generally annular shape about an axis of rotation substantially parallel to the axial direction Y. The tyre 10 is intended for passenger vehicles and has a size of 235 / 55R19. The tyre 10 is a summer tyre. The tyre 10 is shown new, that is to say when it has not yet been driven.

[0109] The tire 10 comprises a tread 14 intended to come into contact with the ground when running. The tire 10 also comprises a conventional structure as described, for example, in applications WO2021250331, WO22074341 or WO2022069819.

[0110] The tire 10 is obtained by molding a green tire in a mold including a plurality of different patterns. Figure 1 In the figure, the joint J between two circumferentially adjacent patterns is represented by a solid line. In the present case, the mold comprises three different patterns, which are randomly distributed so that the tread 14 is molded.

[0111] The tread 14 comprises a tread surface 38 intended to come into contact with the ground via said tread surface 38 when the tire 10 is running on the ground. The tread surface 38 is axially delimited by first and second axial edges 41, 42. The tire 10 has an inner side INT and an outer side EXT defined when the tire 10 is mounted on a vehicle.

[0112] The tread 14 includes an axially central portion P0 and first and second axial side portions P1, P2, which are axially arranged outside the axially central portion P0 and axially on both sides of the axially central portion P0 relative to a midplane M of the tire 10. The first axial side portion P1 is arranged on the same side of the midplane as the outer side EXT, and the second axial side portion P2 is arranged on the same side of the midplane as the inner side INT.

[0113] The tread 14 comprises N>1 main circumferential incisions, in this case N=6 main circumferential grooves indicated by reference numerals 51, 52, 53, 54, 55, 56. The axially outer main circumferential incisions 51, 52, referred to as first and second axially outer main circumferential incisions 51, 52, are axially arranged on both sides of the midplane M of the tire 10 and are the axially outermost main circumferential incisions of the tread 14.

[0114] The first axial side portion P1 and the second axial side portion P2 are respectively arranged axially outside the first axially outer main circumferential cutout 51 and the second axially outer main circumferential cutout 52. The first axial side portion P1 axially extends from the first axial edge 41 of the tread surface 38 to the axially outer edge 43 of the first axially outer main circumferential cutout 51. The second axial side portion P2 axially extends from the second axial edge 42 of the tread surface 38 to the axially outer edge 44 of the second axially outer main circumferential cutout 52.

[0115] The depth of each main circumferential cut 51 to 56 ranges from 4.0 mm to the tread pattern height Hs, preferably from 5.0 mm to the tread pattern height Hs, more preferably from 5.5 mm to the tread pattern height Hs. The depth is each greater than or equal to 50%, preferably 75%, more preferably greater than or equal to 90% of the tread pattern height. In this case, Hs=6.3 mm, the depth of each first axially outer main circumferential cut 51, 52 is equal to 5.8 mm, the depth of each main circumferential cut 53, 56 is equal to 6.1 mm, and the depth of each main circumferential cut 54, 55 is equal to 6.3 mm.

[0116] The axial width of each main circumferential cutout 51 to 56 is respectively greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, more preferably in the range of 5.0 mm to 13.0 mm. In this case, the width of each first and second axially outer main circumferential cutouts 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.

[0117] The axially central portion P0 comprises k≥1 central ribs, in this case k=5 central ribs 61, 62, 63, 64, 65. Each central rib 61 to 65 is axially arranged between a first axially adjacent main circumferential cutout and a second axially adjacent main circumferential cutout of the main circumferential cutouts 51 and 56 and, in this case, is axially bounded by the first axially adjacent main circumferential cutout and the second axially adjacent main circumferential cutout of the main circumferential cutouts 51 to 56.

[0118] The first axial side portion P1 includes N1 first transverse cutouts 81 formed therein. The second axial side portion P2 includes N2 second transverse cutouts 82 formed therein.

[0119] Each central rib 61, 62, 63, 64 and 65 comprises M61, M62, M63, M64 and M65 transverse cutouts formed therein respectively and indicated by reference numerals 71, 72, 73, 74 and 75 respectively.

[0120] Each transverse cut 81, 82 extends over an axial width greater than or equal to 50% of the axial width of each first and second axial side portion P1, P2, respectively, in this case, over an axial width equal to or greater than the axial width of each first and second axial side portion P1, P2. Thus, each first and second transverse cut 81, 82 extends axially from each first and second axial edge 41, 42, respectively, until it opens into each first and second axially outer main circumferential cut 51, 52, respectively. Each transverse cut 81, 82 has a depth greater than or equal to 50% of the tread pattern height Hs of the tire 10, in this case, the depth being equal to 5.3 mm.

[0121] Each transverse cutout 71, 72, 73, 74 and 75 extends over an axial width greater than or equal to 50% of the respective axial width of each central rib 61, 62, 63, 64 and 65, in this case, 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 51, 53, 54, 55, 56, respectively, until it opens into each second main circumferential cutout 53, 54, 55, 56, 52, respectively. The depth of each transverse incision 71, 72, 73, 74 and 75 is greater than or equal to 50% of the tread pattern height Hs of the tire 10, in which case the depth of each incision 71, 75 is equal to 6.0 mm, the depth of each incision 72, 74 is equal to 6.2 mm, and the depth of each incision 73 is equal to 6.3 mm.

[0122] The transverse cuts 81 , 82 , 71 , 72 , 73 , 74 and 75 are called main transverse cuts due to the axial width over which the axial side portions or central ribs extend and the ratio of their depth relative to the tread pattern height.

[0123] Each of the central ribs 61, 62, 65 satisfies 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, there is at least one central rib among the central ribs 61, 62, 65 that has the same number of main transverse incisions as the first axial side portion P1. In this case, the central rib 61 adjacent to the first axial side portion P1 in the axial direction and the central rib 62 satisfy M61 = M62 = N1 = 83. There is also at least one central rib among the central ribs 61, 62, 65 that has the same number of main transverse incisions as the second axial side portion P2. In this case, the central rib 65 adjacent to the second axial side portion P2 in the axial direction satisfies M65 = N2 = 134. It should be noted that N1 and N2 satisfy N2 / N1 ≥ 1.30, preferably N2 / N1 ≥ 1.50 and N2 / N1 ≤ 2.00, preferably N2 / N1 ≤ 1.75. In this case, N2 / N1 = 1.61.

[0124] There is at least one central rib j among the central ribs 61 to 65 that includes Mj main transverse incisions and satisfies N1 < Mj < N2. In this case, the central ribs 63, 64 satisfy M63 = M64 = 106. It should be noted 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. It should also be noted 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.

[0125] R1 can be defined as a spacing ratio equal to the ratio between the minimum distance between two circumferentially consecutive first main transverse cuts 81 (equal to 23.7 mm in this case) and the maximum distance between two circumferentially consecutive first main transverse cuts 81 (equal to 33.9 mm in this case). R2 can also be defined as a spacing ratio equal to the ratio between the minimum distance between two circumferentially consecutive second main transverse cuts 82 (equal to 14.6 mm in this case) and the maximum distance between two circumferentially consecutive second main transverse cuts 82 (equal to 20.9 in this case). Finally, R63 and R64 can be defined as a spacing ratio equal to the ratio between the minimum distance between two circumferentially consecutive main transverse cuts 73, 74 in each central rib 63, 64 (equal to 18.5 mm in this case) and the maximum distance between two circumferentially consecutive main transverse cuts 73, 74 in each central rib 63, 64 (equal to 20.9 mm in this case). In this case, R1=R2=R63=R64=0.70.

[0126] This makes it possible to define an overlapping level T1,63=T1,64=[(N1 / R1)-(M63×R63)] / [(M63 / R63)-(N1×R1)]=[(N1 / R1)-(M64×R64)] / [(M64 / R64)-(N1×R1)] between the first axially outer portion P1 and each central rib 63, 64. This also makes it possible to define an overlapping level T63,2=T64,2=[(M63 / R63)-(N2×R2)] / [(N2 / R2)-(M63×R63)]=[(M64 / R64)-(N2×R2)] / [(N2 / R2)-(M64×R64)] between the second axially outer portion P2 and each central rib 63, 64.

[0127] 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 product of the number of main transverse cuts and the pitch ratio of the first and second axially outer portions P1, P2 and each central rib 63, 64 The minimum value of , in this case it is the product of the number N1 of main transverse cuts 81 in the first axially outer part P1 and the spacing 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 and the spacing ratio of the first and second axially outer parts P1, P2 and each central rib 63, 64, in this case it is the ratio between the number N2 of main transverse cuts 82 in the second axially outer part P2 and the spacing ratio R2.

[0128] T1,63, T1,64, T63,2 and T64,2 satisfy 0.40≤T1,63=T1,64≤0.60 on the one hand, 0.40≤T63,2=T64,2≤0.60 on the other hand, and finally 0.50≤Rpg≤0.60. In this case, T1,63=T1,64=0.48, T63,2=T64,2=0.49 and Rpg=0.55.

[0129] 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, in which case C / N1=28, on the other hand the ratio C / N2 ranges from 14 to 20, preferably from 16 to 19, in which case C / N2=17, and finally the ratio C / M63=C / M64 ranges from 18 to 23, preferably from 20 to 23, in which case C / M63=C / M64=22.

[0130] Each main transverse cut 71, 72, 73, 74 and 75 formed in each central rib 61, 62, 63, 64 and 65 respectively leads to each first circumferential cut and second circumferential cut that axially defines the central rib 61, 62, 63, 64 and 65 in the first open area and the second open area 711, 712, 721, 722, 731, 732, 741, 742, 751, 752 respectively.

[0131] For example, considering the circumferentially adjacent first and second main transverse cuts 75A, 75B formed in the central rib 65, the orientation AZ1 of the points of the first open area 751 of the first main transverse cut 75A is substantially aligned circumferentially with the orientation AZ2 of the points of the second open area 752 of the second main transverse cut 75B. The cuts 71, 72, 73 and 74 formed in each central rib 61, 62, 63 and 64, respectively, also reproduce this circumferentially aligned feature.

[0132] The main transverse cutouts 81 , 82 and 71 to 75 and the main circumferential cutouts 51 to 56 define a plurality of blocks chamfered on each of their circumferential edges and on each of their transverse edges.

[0133] Figure 2 and Figure 3 A first main transverse cut 81 and a main transverse cut 75 are shown respectively. The first main transverse cuts 81 are identical to each other and, considering similar factors, are identical to the second main transverse cut 82. The main transverse cut 75 is identical to the main transverse cuts 71, 72, 73 and 74, considering similar factors.

[0134] Reference Figure 2 , 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 radially inner portion 81i, a radially middle portion 81m and a radially outer portion 81e. The radially 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 main transverse cut 81, and the radially outer portion 81e is the radially outermost portion of the first main transverse cut 81. The radially middle portion 81m extends radially at a height H2 equal to 50% of the height H81 of the first main transverse cut 81. The radially inner portion 81i and the radially outer portion 81e each extend radially at heights H1, H3 equal to 25% of the height H81 of the first main transverse cut 81, respectively.

[0135] The maximum width Lmax1 of the radially inner portion 81i is strictly greater than the maximum width Lmax3 of the radially outer portion. In the cross-sectional plane II-II', the minimum width Lmin81 of each first main transverse cutout 81 is equal to 0.30 mm in this case. The same is true for the second main transverse cutout 82. In this case, Lmax1 = 1.16 mm and Lmax3 = 1.00 mm.

[0136] In at least one region 90, 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 less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm. Figure 2 In the example shown, at least 50%, preferably 75%, of the first main transverse cuts 81 (in this case each first main transverse cut 81) have a width less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm over at least 10% of their height H81 (in this case represented by the height portion H4) and along at least 10% of their length. The region 90 of at least 50%, preferably at least 75% of the first main transverse cuts 81 (in this case each first main transverse cut 81) is at least partially (in this case entirely) located in the radial middle portion 81m. The region 90 extends over a continuous surface that accounts for at least 10% and at most 80%, preferably at most 50%, of the surface of each leading edge face 81a and trailing edge face 81f of each first main transverse cut 81.

[0137] As described above, the same is true for the second main transverse cut 82 .

[0138] Reference Figure 3 , the width of each main transverse cut 75 varies with the radial advancement of 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 middle portion 75m and a radially outer portion 75e. The radially inner portion 75i is arranged 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 main transverse cut 75, and the radially outer portion 75e is the radially outermost portion of the main transverse cut 75. The radially middle portion 75m extends radially at a height H2' equal to 50% of the height H75 of the main transverse cut 75. The radially inner portion 75i and the radially outer portion 75e each extend radially at heights H1', ​​H3' equal to 25% of the height H75 of the main transverse cut 75, respectively.

[0139] In at least one region 92, at least 50%, preferably at least 75%, of the main transverse cuts 75 (in this case, each main transverse cut 75) formed in the central rib 65 have a width less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm. Figure 3In the example shown, at least 50%, preferably 75%, of the main transverse cuts 75 (in this case, each main transverse cut 75) have a width less than or equal to 0.50 mm, preferably less than or equal to 0.40 mm, more preferably less than or equal to 0.35 mm over at least 10% of their height H (in this case represented by height portion H4') and along at least 10% of their length.

[0140] 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 edge face 75 a and trailing edge face 75 f of each main transverse cutout 75 .

[0141] In the cross-sectional plane III-III', the minimum width Lmin75 of each main transverse cut 75 is equal to 0.24 mm in this case. At least 50%, preferably at least 75%, of the area 92 of the main transverse cuts 75 (in this case each main transverse cut 75) is at least partially (in this case completely) located in the radial middle portion 75m. The same is true for the main transverse cuts 71, 72, 73, 74.

[0142] Comparison test

[0143] Wear measurement

[0144] The tire 10 is compared with a control tire T having a tread as shown in FIG. Figure 4 As shown. The treads of tire 10 and control tire T are made of the same material. Unlike tire 10, control tire T satisfies N1=N2, and there is no region where the width of the main transverse cut formed in each axial side portion is less than or equal to 0.50 mm. Specifically, the width of the main transverse cut formed in each axial side portion is equal to 1.0 mm, 1.2 mm, and 1.5 mm (depending on the cut).

[0145] Four tires 10 and T are driven on a single vehicle at a time, and the wear of the tire mounted on the front of the vehicle is measured over mileage (about 15,000 km). Then, in order to shorten the test, the wear is extrapolated until a portion of the tread reaches the maximum wear indicated by the specified wear indicator. The average value of the two tires mounted on the front of the vehicle is then calculated.

[0146] The maximum mileage achieved by each tire (which reflects the useful life of the tire) and the mass loss experienced by each tire when reaching that maximum mileage are then collated. The results are collated in Table 1 below, using tire T as base 100.

[0147] [Table 1]

[0148] T 10 Service life (base 100) 100 117 Mass loss (base 100) 100 94

[0149] Unlike the control tire T, whose service life is determined by the axial side portion arranged on the inner side of the vehicle reaching the prescribed wear indicator too early, the service life of the tire 10 is determined by the axial side portion arranged on the inner side of the vehicle reaching the prescribed wear indicator later and the axial side portion arranged on the outer side of the vehicle reaching the prescribed wear indicator almost at the same time. Therefore, the present invention makes the wear of the tread more uniform and avoids the hardest part of the tire reaching the wear limit too early. Therefore, the mileage of the tire according to the present invention can be greater than that of the control tire T.

[0150] This is confirmed by the mass loss, which is greater for tire 10 compared to the mass loss for control tire T. In particular, due to the more uniform wear of the entire tread, before reaching the maximum mileage, tire 10 loses more mass than control tire T, a large part of which still has a large amount of material to be worn away, while only a part (in this case the axial side part arranged on the inside of the vehicle) has been worn to such an extent that the prescribed wear indicator is reached.

[0151] Noise Assessment

[0152] Noise tests were conducted to evaluate cavity noise, beat noise and brake noise at speeds below 90 km / h for tire 10, tire T and a particularly quiet reference tire R. These tests were conducted subjectively by the driver and the results are collated in Table 2 below, where:

[0153] - The symbol "=" indicates that the noise is substantially equivalent to the noise of the reference tire R,

[0154] - The symbol "-" indicates that the noise is slightly increased compared to the reference tire R.

[0155] - The symbol "--" indicates that the noise is significantly increased compared to the reference tire R.

[0156] - The sign "+" indicates a slight reduction in noise compared to the reference tire R.

[0157] [Table 2]

[0158] T 10 Cavity noise -- ＝ Beat Noise - + Braking noise ＝ +

[0159] It should 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.

[0160] The present invention is not limited to the above-described embodiments.

Claims

1. A tire (10) comprising a tread (14) intended to come into contact with the ground via a tread surface (38) when the tire (10) is running, the tread (14) comprising: - main circumferential cuts (51, 52, 53, 54, 55, 56), the depth of the main circumferential cuts (51, 52, 53, 54, 55, 56) being greater than or equal to 50% of the tread pattern height (Hs), and comprising a first axially outer main circumferential cut and a second axially outer main circumferential cut (51, 52) arranged axially on both sides of a midplane (M) of the tire (10), the first axially outer main circumferential cut and the second axially outer main circumferential cut (51, 52) being the axially outermost main circumferential cuts of the tread (14), - a first axial side portion (P1) which is axially arranged outside the first axially outer main circumferential cutout (51) and extends 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 cutout (51), a second axial side portion (P2) arranged axially outside the second axially outer main circumferential cutout (52) and extending axially from the second axial edge (42) of the tread surface (38) to the axially outer edge (44) of the second axially outer main circumferential cutout (52), The first axial side portion (P1) comprises N1 first transverse cutouts (81) formed in the first axial side portion (P1), The second axial side portion (P2) includes N2 second transverse cutouts (82) formed in the second axial side portion (P2), wherein N2>N1, Each first and second transverse cut (81, 82), referred to as main transverse cuts, extends over an axial width greater than or equal to 50% of the axial width of each first and second axial side portion, respectively, and has a depth greater than or equal to 50% of the tread height (Hs) of the tire (10), Characterized in that, in at least one region (90), at least 50% of the first main transverse cuts (81) and at least 50% of the second main transverse cuts (82) have a width less than or equal to 0.50 mm, The tire comprises k≥1 central ribs i (61, 62, 63, 64, 65), the central ribs i (61, 62, 63, 64, 65) being axially bounded by first axially adjacent main circumferential cuts and second axially adjacent main circumferential cuts (51, 52, 53, 54, 55, 56), the central ribs i (61, 62, 63, 64, 65) or each central rib i (61, 62, 63, 64, 65) being included in Mi>1 transverse cuts (71, 72, 73, 74, 75) are formed in the central rib i (61, 62, 63, 64, 65), each transverse cut (71, 72, 73, 74, 75) formed in the central rib i, called main transverse cuts, extends over an axial width greater than or equal to 50% of the axial width of the central rib i and has a depth greater than or equal to 50% of the tread pattern height (Hs) of the tire (10), and there is at least one central rib j (63, 64), said central rib j (63, 64) comprising Mj>1 main transverse cuts (73, 74) formed in said central rib j, and satisfying N1 <Mj<N2。 2. Tyre (10) according to the preceding claim, wherein: In at least one area (90), at least 75% of the first main transverse cuts (81) and at least 75% of the second main transverse cuts (82), preferably each first main transverse cut (81) and each second main transverse cut (82) has a width less than or equal to 0.35 mm.

3. Tyre (10) according to any one of the preceding claims, wherein: The region (90) extends over at least 10% of the height and along at least 10% of the length of at least 50% of the first main transverse cuts (81) and at least 50% of the second main transverse cuts (82).

4. Tyre (10) according to any one of the preceding claims, wherein: Each of the first and second main transverse cutouts (81, 82) has a radial middle portion (81m), a radial outer portion (81e) and a radial inner portion (81i), wherein the radial outer portion (81e) is arranged radially outside the radial middle portion (81m), the radial inner portion (81i) is arranged radially inside the radial middle portion (81m), the radial middle portion (81m) extends radially at a height (H2) equal to 50% of the height (H) of the first and second main transverse cutouts (81, 82), and each radial inner portion (81i) and the radially outer portion (81e) extend radially at a height (H1, H3) equal to 25% of the height (H) of the first main transverse cut and the second main transverse cut (81, 82), and at least 50% of the first main transverse cut (81) and at least 50% of the second main transverse cut (82), preferably at least 75% of the first main transverse cut (81) and at least 75% of the second main transverse cut (82), and more preferably an area (90) of each first main transverse cut (81, 82) is at least partially located in the middle portion (81m).

5. Tyre (10) according to any one of the preceding claims, wherein: 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 each of the first main transverse incisions and the second main transverse incisions (81, 82) has a radially inner portion (81i) and a radially outer portion (81e) arranged radially outside the radially inner portion (81i), the radially inner portion (81i) being the radially innermost portion of the first main transverse incisions and the second main transverse incisions (81, 82), the radially outer portion (81e) being the outermost portion of the first main transverse incisions and the second main transverse incisions (81, 82), and the maximum width (Lmax1) of the radially inner portion (81i) being strictly greater than the maximum width (Lmax3) of the radially outer portion (81e).

6. Tyre (10) according to any one of the preceding claims, wherein: Each of the first main transverse incisions and the second main transverse incisions (81, 82) extends axially from each first axial edge and second axial edge (41, 42) of the tread surface (38) until it leads to each first outer main circumferential incision and second outer main circumferential incision (51, 52) respectively.

7. Tyre (10) according to any one of the preceding claims, wherein: N2 / N1 ≥ 1.30, preferably N2 / N1 ≥ 1.

50.

8. Tyre (10) according to any one of the preceding claims, wherein: Each main transverse incision (71, 72, 73, 74, 75) formed in each central rib portion i extends axially from each first main circumferential incision (51, 52, 53, 54, 55, 56) until it leads to each second main circumferential incision (51, 52, 53, 54, 55, 56).

9. Tyre (10) according to any one of the preceding claims, wherein: Each central rib portion i (61, 62, 65) other than the central rib portions j (63, 64) includes Mm > 1 main transverse incisions (71, 72, 75), the main transverse incisions (71, 72, 75) being formed in the central rib portions i (61, 62, 65) other than the central rib portions j (63, 64), extending over an axial width greater than or equal to 50% of the axial width of the central rib portions i (61, 62, 65) other than the central rib portions j (63, 64), and having a depth greater than or equal to 50% of the tread pattern height (Hs) of the tire (10). Each central rib portion i (61, 62, 65) other than the central rib portions j (63, 64) satisfies N1 ≤ Mm ≤ Mj < N2 or N1 < Mj ≤ Mm ≤ N2.

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

25.

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

12. Tyre (10) according to any one of the preceding claims, wherein: N1, N2 and Mj satisfy 0.50≤[Min(N1×R1; N2×R2; Mj×Rj) / Max(N1 / R1; N2 / R2; Mj / Rj)]^(0.5)≤0.60, where: - R1 is a spacing ratio equal to the ratio between the minimum distance between two first circumferentially consecutive main transverse cuts (81) and the maximum distance between two first circumferentially consecutive main transverse cuts (81), - R2 is a spacing ratio equal to the ratio between the minimum distance between two second circumferentially consecutive main transverse cuts (82) and the maximum distance between two second circumferentially consecutive main transverse cuts (82), - Rj is a spacing ratio equal to the ratio between the minimum distance between two circumferentially consecutive main transverse cuts (71, 72, 73, 74, 75) of the central rib j (61, 62, 63, 64, 65) 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 central rib j or each central rib j, -Min(N1×R1;N2×R2; Mj×Rj) is the minimum value of the product of the number of main transverse cutouts (81, 82, 71, 72, 73, 74, 75) and the ratio of the pitches of the first and second axially outer portions (P1, P2) and of the central rib j (61, 62, 63, 64, 65) or each central rib j (61, 62, 63, 64, 65), -Max(N1 / R1; N2 / R2; Mj / Rj) is the maximum value of the ratio between the number of main transverse cuts (81, 82, 71, 72, 73, 74, 75) and the spacing ratio between the first axially outer part and the second axially outer part (P1, P2) and the central rib j (61, 62, 63, 64, 65) or each central rib j (61, 62, 63, 64, 65).

13. Tyre (10) according to any one of the preceding claims, wherein: In at least one area (92), at least 50%, preferably at least 75%, and more preferably each main transverse cut (71, 72, 73, 74, 75) formed in the central rib i (61, 62, 63, 64, 65) has a width less than or equal to 0.50 mm.

14. Tyre (10) according to the preceding claim, wherein: The area (92) is formed in the central rib i (61, 62, 63, 64, 65) or each central rib i (61, 62, 63, 64, 65) over at least 50%, preferably at least 75%, more preferably at least 10% of the height of each main transverse cut (71, 72, 73, 74, 75) and extends along at least 10% of the length.

15. Tyre (10) according to claim 13 or 14, wherein: Each main transverse cutout (71, 72, 73, 74, 75) formed in the central rib-shaped portion i (61, 62, 63, 64, 65) or each central rib-shaped portion i (61, 62, 63, 64, 65) has a radial middle portion (75m), a radial outer portion (75e) and a radial inner portion (75i), the radial outer portion (75e) being arranged radially on the outside of the radial middle portion, the radial inner portion (75i) being arranged radially on the inside of the radial middle portion (75m), the radial middle portion (75m) extending radially at a height equal to 50% of the height of the main transverse cutout (71, 72, 73, 74, 75), and each radial inner portion and radial outer portion (75i, 75e) extending radially at a height equal to 50% of the height of the main transverse cutout (71, 72, 73, 74, 75). The central rib-shaped portion i (61, 62, 63, 64, 65) or each central rib-shaped portion i (61, 62, 63, 64, 65) extends over 25% of its height, and at least 50% of the main transverse cuts (71, 72, 73, 74, 75) formed in the central rib-shaped portion i (61, 62, 63, 64, 65), preferably at least 75% of the main transverse cuts (71, 72, 73, 74, 75) formed in the central rib-shaped portion i (61, 62, 63, 64, 65) or each central rib-shaped portion i (61, 62, 63, 64, 65), more preferably the area (92) of each main transverse cut (71, 72, 73, 74, 75) formed in the central rib-shaped portion i (61, 62, 63, 64, 65) is at least partially located in the middle part (75m).

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