Low noise tires

Abstract

A tire (10) for a private passenger vehicle comprises an axial central portion and an axial side portion. The axial central portion and each axial side portion only meet one of the conditions I, II, and III: the I-portion does not include any transverse cuts (90, 90'); the II-portion includes N transverse cuts (90, 90') arranged so that πx OD / N ≥ 40 mm; the III-portion includes N transverse cuts (90, 90') arranged so that πx OD / N ≤ 24 mm, the axial central portion or the axial side portion meets the condition I or II, and the axial central portion or the axial side portion meets the condition III.

Description

Technical Field

[0001] The present invention relates to a tire for passenger vehicles. A tire is understood to mean a casing 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 presenting a generally toroidal shape that is rotationally symmetrical about the main axis of the tire. Background Art

[0002] A tyre of size 245 / 45R18 is known in the prior art, sold under the Michelin trade name and belonging to the PRIMACY 4 series. This tyre offers an excellent compromise in performance, in particular between grip on wet or dry ground and the external noise generated by the tyre.

[0003] However, new regulations relating to exterior noise generated by tires, particularly in Europe, require that this exterior noise be reduced.

[0004] Therefore, tire manufacturers have developed tires for reducing such external noise, for example by changing the tread pattern of the tire, as disclosed in WO2018 / 199273, in which the grooves are provided with protrusions that cause the resonance frequency of the air column in these grooves to deviate from the frequency range audible to the human ear. However, providing the grooves with these protrusions increases the complexity of manufacturing the corresponding molds, thereby increasing the cost of the relevant tires.

[0005] Another currently known solution is disclosed in WO2010 / 069510, which consists in modifying the structure of the tire by radially inserting a sublayer of material containing a high-density filler between the tread layer of the tire and the crown reinforcement of the tire. This sublayer does not make it possible to modify the frequency of the emitted noise, as in WO2018 / 199273, but rather to attenuate the acoustic power of this noise. However, providing the tire with such a sublayer not only increases the cost of the tire, but also increases the mass of the tire, thereby increasing the rolling resistance of the tire.

[0006] The object of the present invention is to reduce the external noise generated by a tire in a simple manner and without additional costs compared to tires of the prior art. Summary of the invention

[0007] To this end, the subject of the invention is a tire for passenger vehicles, said tire having an outer diameter OD and comprising a tread intended to come into contact with the ground when the tire is running, via a tread surface, said tread surface being axially delimited by a first axial edge and a second axial edge of the tread surface, said tread comprising:

[0008] - an axially central portion, comprising main circumferential grooves having a depth greater than or equal to 50% of the tread pattern height and comprising at least a first main circumferential groove and a second main circumferential groove, each arranged axially one on each side of a mid-plane of the tire, the first main circumferential groove and the second main circumferential groove being the main circumferential grooves axially closest to the outside of the tread, the axially central portion extending axially from the axially outer edge of the first main circumferential groove to the axially outer edge of the second main circumferential groove, the axially central portion comprising at least one central rib, the central rib or each central rib being axially delimited by two main circumferential grooves having a depth greater than or equal to 50% of the tread pattern height,

[0009] a first axial side portion and a second axial side portion, arranged axially outside the axial central portion and one on each side of the axial central portion axially relative to a midplane of the tire, and arranged such that:

[0010] - said first axial side portion extends axially from a first axial edge of the tread surface to an axially outer edge of the first main circumferential groove,

[0011] - said second axial side portion extends axially from a second axial edge of the tread surface to an axially outer edge of the second main circumferential groove,

[0012] The central rib or each central rib and the first axial side portion and the second axial side portion each include at least one axial portion that satisfies only one of the following conditions I, II, III, and the axial width of all axial portions of the central rib or each central rib and the first axial side portion and the second axial side portion that respectively satisfies only one of the conditions I, II, III is greater than or equal to 70% of the axial width of the central rib or each central rib and the first axial side portion and the second axial side portion respectively:

[0013] I - the axial portion does not include any transverse cutouts having a depth greater than or equal to 20% of the tread pattern height and an axial length greater than or equal to 20% of the axial width of the central rib or of the axial side portions, said axial portion may include at least one circumferential cutout having a depth strictly less than 50% of the tread pattern height,

[0014] II - the axial portion comprises transverse cuts having a depth greater than or equal to 20% of the tread pattern height and an axial length greater than or equal to 20% of the axial width of the central rib or of the axial side portions, the entire N transverse cuts of the axial portion having a depth greater than or equal to 20% of the tread pattern height and an axial length greater than or equal to 20% of the axial width of the central rib or of the axial side portions being arranged such that πx OD / N ≥ 40 mm, the axial portion may comprise at least one circumferential cut having a depth strictly less than 50% of the tread pattern height,

[0015] III - the axial portion comprises transverse cuts having a depth greater than or equal to 20% of the tread pattern height and an axial length greater than or equal to 20% of the axial width of the central rib or of the axial side portions, all N transverse cuts having a depth greater than or equal to 20% of the tread pattern height and an axial length greater than or equal to 20% of the axial width of the central rib or of the axial side portions being arranged such that πx OD / N ≤ 24 mm, said axial portion may comprise at least one circumferential cut having a depth strictly less than 50% of the tread pattern height,

[0016] At least the central rib or an axial portion of a central rib or an axial portion of the first axial side portion or an axial portion of the second axial side portion satisfies condition I or II,

[0017] At least the central rib or an axial portion of a central rib or an axial portion of the first axial side portion or an axial portion of the second axial side portion satisfies condition III.

[0018] The inventors have reduced the external noise generated by the tire due to the fact that one or more of the central ribs and the axial side portions comprise no or few transverse cutouts, or comprise a large number of transverse cutouts.

[0019] Specifically, the inventors of the present invention have utilized the fact that the external noise generated by the tire originates from the excitation of the cutouts on the one hand and from the resonance of the mechanical structure formed by the tire on the other hand. The inventors have found that by avoiding the superposition of the noise spectrum originating from the excitation of the cutouts and the noise spectrum originating from the mechanical structure, the resonance of the frequencies and harmonics of these spectra is avoided, thereby significantly reducing the external noise emitted by the tire.

[0020] More specifically, the frequency spectrum of the noise originating from the mechanical structure is between 600 Hz and 1100 Hz, which frequency spectrum mainly depends on the length of the tire contact patch and the size and structure of the tire. According to the present invention, the frequency spectrum of the noise excited by the transverse cuts of the central rib or each central rib and the first axial side portion and the second axial side portion is shifted relative to the frequency spectrum ranging from 600 Hz to 1100 Hz, thereby reducing the external noise emitted by the tire. Therefore, for each central rib and each axial portion of each of the first axial side portion and the second axial side portion, the number of cuts in the tire contact patch can be increased (i.e., the average spacing πx OD / N can be reduced), thereby shifting the frequency spectrum of the noise excited by the transverse cuts to high frequencies. Conversely, for each central rib and each axial portion of each of the first axial side portion and the second axial side portion, the number of cuts in the tire contact patch can be reduced (i.e., the average spacing πx OD / N can be increased), thereby shifting the frequency spectrum of the noise excited by the transverse cuts to low frequencies. The excitation also depends on the driving speed of the vehicle, so each N value within the interval of the present invention can be selected according to the speed at which the vehicle is used.

[0021] According to the present invention, the central rib or at least one axial portion of a central rib and at least one axial portion of the first axial side portion and the second axial side portion satisfy condition I or II and condition III at least once. Specifically, if the rib or all ribs and the first axial central portion and the second axial central portion each satisfy only condition I or II, the grip of the tire on wet ground will be affected. If the rib or all ribs and the first axial central portion and the second axial central portion each satisfy only condition III, the rigidity of the tread will be excessively reduced in the longitudinal direction due to the excessive number of transverse cuts, which will lead to a decrease in grip on dry ground.

[0022] Within the scope of the present invention, each axial portion either satisfies a single condition among conditions I, II, III or does not satisfy one of conditions I, II, III. Therefore, the axial development along the central rib or the axial side portion includes a plane perpendicular to the axis of rotation that satisfies one of conditions I, II, III to a plane perpendicular to the axis of rotation that does not satisfy conditions I, II, III, i.e., includes from one axial portion to another axial portion. Similarly, the axial development along the central rib or the axial side portion includes a plane perpendicular to the axis of rotation that satisfies one of conditions I, II, III to a plane perpendicular to the axis of rotation that satisfies another of conditions I, II, III, i.e., includes from one axial portion to another axial portion. Finally, the axial development along the central rib or the axial side portion includes a plane perpendicular to the axis of rotation that satisfies one of conditions I, II, III to a plane perpendicular to the axis of rotation that satisfies the same conditions I, II, III, i.e., remains in the same axial portion.

[0023] The fact that the transverse incisions taken into account in the calculation of the average spacing have a depth greater than or equal to 20% of the tread pattern height and an axial length greater than or equal to 20% of the axial width of the central rib or axial side portion concerned means that it is not necessary to take into account transverse incisions whose depth or axial length are not sufficient to cause external noise emanating from the tire.

[0024] The fact that the axial width of the central rib or each central rib and the first and second axial side portions, respectively, of all axial portions that only meet one of the conditions I, II, III is greater than or equal to 70% of the axial width of the central rib or each central rib and the first and second axial side portions, respectively, means that embodiments can be considered in which at least an insignificant portion (in this case representing less than 30% of the axial width of the central rib or each central rib and the first and second axial side portions, respectively) does not meet any of the conditions I, II and III. The fact that the axial width of the portion or portions that does not meet any of the conditions I, II and III is relatively small ensures that the portion or portions contribute little or nothing to the external noise emitted by the tire and are prone to resonate with the tire structure-borne noise.

[0025] Furthermore, the fact that the central rib or each central rib and the first and second axial side portions each comprise at least one axial portion that satisfies only one of the conditions I, II, III makes it possible to consider embodiments in which distinct axial portions of the central rib or each central rib and the first and second axial side portions each satisfy or do not satisfy different conditions I, II, III. According to the invention, the sum of the axial widths of the one or more axial portions that each satisfy only one of the conditions I, II, III is greater than or equal to 70% of the axial width of the central rib or each central rib and the first and second axial side portions, respectively.

[0026] In the case where an axial portion of a rib or an axial side portion and two adjacent axial portions of the same rib or the same axial side portion do not satisfy the same conditions I, II, III, or in the case where an axial portion of a rib or an axial side portion does not satisfy any one of the conditions I, II and III and two adjacent axial portions of the same rib or the same axial side portion each satisfy only one of the conditions I, II, III, there are two transition areas located between the axial portion in question and each adjacent axial portion, the spectrum of the external noise emitted by these two transition areas tends to overlap with the spectrum of the tire structure-borne noise. Therefore, the number of transition areas will be minimized or even eliminated. This will firstly minimize the number of conditions I, II, III satisfied on the same central rib or the same axial side portion, and secondly, if only one of the conditions I, II, III is satisfied on the same rib or the same axial side portion, the axial portions that do not satisfy any one of the conditions I, II and III and that may be inserted axially between different axial portions satisfying a single condition I, II and III will be minimized or even eliminated.

[0027] OD is the tire's outside diameter measured in the mid-plane of the tire. Therefore, π x OD is the tire's circumference measured in the mid-plane of the tire. N and OD or π x OD are measured on an unloaded tire and can be measured on an inflated or non-inflated tire. The important thing is that N and OD or π x OD are measured under the same conditions.

[0028] The axial width of the central rib, the axial width of the axial central portion or the axial side portion, the axial width of the axial portion of the central rib, the axial width of the axial portion of the axial side portion, is the axial distance between the following two planes: the two planes are perpendicular to the rotation axis of the tire and each plane passes through the axial inner edge and the axial outer edge of the central rib, the axial inner edge and the axial outer edge of the axial central portion or the axial side portion, the axial inner edge and the axial outer edge of the axial portion of the central rib, and the axial inner edge and the axial outer edge of the axial portion of the axial side portion.

[0029] The axial length of a transverse cut is the axial distance between two planes perpendicular to the axis of rotation of the tyre and each passing through an axially inside end and an axially outside end of the transverse cut.

[0030] According to the invention, the central rib or at least a portion of one central rib, or at least a portion of the first axial side portion or at least a portion of the second axial side portion comprises transverse cutouts. The cutouts are grooves or sipes and form spaces opening onto the tread surface.

[0031] A sipe or groove has two main characteristic dimensions on the tread surface: width and curve length, with the curve length being at least equal to twice the width. Thus, a sipe or groove is delimited by at least two main sides that determine its curve length and are connected by a bottom surface, the distance between these two main sides being non-zero, called the cut width.

[0032] On a new tire, the width of the cut is the maximum distance between the two main side faces, measured at the radial dimension coinciding with the tread surface when the cut has no chamfer, and at the radially outermost radial dimension of the cut and the radially innermost dimension of the chamfer when the cut has a chamfer. In the case of a cut having two portions with different widths W1 and W2 (satisfying 0.67≤W1 / W2≤1.50), the cut width is the width of the portion with the maximum curve length. The different portions are separated from each other by discontinuities in the curvature of each side face of each portion (e.g., local or abrupt steps or local or abrupt narrowings).

[0033] On a new tire, the cut depth 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 cut depth is called the tread height.

[0034] The sipes meet a distance between the main sides suitable for allowing the main sides delimiting said sipes to come into at least partial contact when passing through the contact patch, in particular when the tyre is new and under normal running conditions, these normal running conditions including in particular the fact that the tyre is under nominal load and its nominal pressure.

[0035] The grooves satisfy a distance between the main flanks such that these do not contact one another under normal running conditions, which include in particular the fact that the tyre is under nominal load and its nominal pressure.

[0036] The incision may be a transverse incision or a circumferential incision.

[0037] The transverse incision satisfies that the incision extends along an average direction, which forms an angle with the circumferential direction of the tire that is strictly greater than 30°, preferably greater than or equal to 45°. 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, that is, not interrupted by a tread block or another incision, so that the two main sides that determine its length are not interrupted over the length of the transverse incision. The transverse incision can also be discontinuous, that is, 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.

[0038] The circumferential incision is such that the incision extends in an average direction, the 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. The average direction is the shortest curve connecting the two ends of the incision and parallel to the tread surface. In the case where the circumferential incision is continuous, the two ends coincide with each other and are joined by a curve forming a complete circumference of 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 of 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 by one or more tread blocks and / or one or more incisions over the entire circumference of the tire.

[0039] The main direction of the cut is the direction in which the curve equidistant from each edge of the cut extends in the radial dimension of the tread surface. The curve length is the length between the ends of the cut measured along the curve equidistant from each edge of the cut in the radial dimension of the tread surface.

[0040] In the case of a circumferential cutout outside the mid-plane of the tyre, the sides are the axially inner side and the axially outer side, the axially inner side being arranged axially inside the axially outer side at a given azimuth angle relative to the mid-plane.

[0041] In the case of a transverse cut, the side faces are the leading face, which for a given circumferential line has its edge entering the contact patch before the edge of the trailing face, and the trailing face.

[0042] The circumferential grooves having a depth greater than or equal to 50% of the tread pattern height and included between the first and second axial side portions and one or more central ribs are called main circumferential grooves. Thus, in cases where the tread pattern height is at least twice the height of the prescribed tread wear indicator (which represents the vast majority of passenger vehicle tires), the depth of these main circumferential grooves can continue to more than half of the wearable tread height of the tire. Thus, such main circumferential grooves having a depth greater than or equal to 50% of the tread pattern height do not disappear before the tire has worn away at least 50% of its wearable tread height. The wearable tread height is defined as the radial height between the radially outermost point of the prescribed wear indicator when the tire is new and the projection of said radially outermost point on the ground when the tire is running. Such prescribed tread wear indicators are defined, for example, by United Nations regulations R30 and R54, American standard FMVSS139 or Chinese standard GB97743 and seek to enable tire users to recognize a prescribed tire tread wear threshold beyond which driving is dangerous, especially on wet ground.

[0043] Conventionally, within the meaning of the 2019 European Tyre and Rim Technical Organisation (ETRTO) standard, the tread surface is determined on a tyre mounted on a nominal rim and inflated to its nominal pressure. If there is a clear boundary between the tread surface and the rest of the tyre, the axial width of the tread surface is simply measured. If the tread surface is continuous with the outer surface of the tyre sidewall, the axial limit of the tread surface passes through the following point: at this point, 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 section plane where the absolute value of the angle is equal to 30°, the radially outermost point is used.

[0044] The tyre according to the invention has a generally toroidal 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: axial, circumferential and radial.

[0045] 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.

[0046] 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 centred on the axis of rotation of the tire).

[0047] 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.

[0048] The expression “median plane of the tire” (indicated by M) means the plane perpendicular to the axis of rotation of the tire, situated axially centred between the two beads and passing through the axial middle of the crown reinforcement.

[0049] The expression "equatorial circumferential plane of the tire" (indicated by E) means that in a meridian section plane, this plane passes through the equator of the tire and is perpendicular to the median plane and to the radial direction. The equator of the tire is the axis in a meridian section plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions) which is parallel to the axis of rotation of the tire and is 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, such as a rim, the distance between these two points being equal to H.

[0050] The expression “meridian plane” means a plane parallel to the axis of rotation of the tyre, containing this axis of rotation and perpendicular to the circumferential direction.

[0051] “Radially inside” and “radially outside” mean “closer to the tire's axis of rotation” and “further away from the tire's axis of rotation”, respectively. “Axially inside” and “axially outside” mean “closer to the tire's mid-plane” and “further away from the tire's mid-plane”, respectively.

[0052] The term "bead" means the portion of the tyre intended to enable the tyre to be attached to a mounting support, such as a wheel comprising a rim. Thus, each bead is particularly intended to be in contact with a flange of the rim so that it can be attached.

[0053] Any numerical interval represented by the expression "between a and b" represents a numerical range extending from greater than a to less than b (i.e., excluding the endpoints a and b), while any numerical interval represented by the expression "a to b" means a numerical range extending from a all the way to b (i.e., including the strict endpoints a and b).

[0054] The tire of the invention is intended for passenger vehicles as defined according to the European Tyre and Rim Technical Organization or "ETRTO" standard of 2019. This tire has a section in the meridian section plane characterized by a section height H and a nominal section width S satisfying, according to the meaning of the European Tyre and Rim Technical Organization (or "ETRTO") standard of 2019, a ratio H / S expressed as a percentage of at most 90, preferably at most 80, more preferably at most 70 and at least 30, preferably at least 40, and a nominal section width S of at least 115 mm, preferably at least 155 mm, more preferably at least 175 mm and at most 385 mm, preferably at most 315 mm, more preferably at most 285 mm, even more preferably at most 255 mm. In addition, a diameter D at the flange, which defines the diameter of the mounting rim of the tire, is at least 12 inches, preferably at least 16 inches and at most 24 inches, preferably at most 20 inches.

[0055] Advantageously, in order to take into account only those transverse incisions which, due to their depth, contribute most to the external noise emitted by the tire, the depth of all N transverse incisions considered when calculating the average spacing is greater than or equal to 30% of the tread pattern height, preferably greater than or equal to 40% of the tread pattern height.

[0056] Similarly, in order to take into account only those transverse incisions which, due to their width, contribute most to the external noise emitted by the tire, the axial length of all N transverse incisions to be considered when calculating the average spacing is greater than or equal to 30% of the axial width of the central rib or of the axial side portion, preferably greater than or equal to 50% of the axial width of the central rib or of the axial side portion, and even more preferably greater than or equal to 75% of the axial width of the central rib or of the axial side portion.

[0057] Of course, in order to take into account those transverse incisions which, due to their width and axial length, contribute most to the external noise emitted by the tire, in a highly preferred embodiment, the calculation of the average spacing will advantageously take into account those transverse incisions whose depth is greater than or equal to 40% of the tread pattern height and whose axial length is greater than or equal to 75% of the axial width of the central rib or of the axial side portions.

[0058] In a preferred embodiment, at least one axial portion of the central rib or each central rib satisfies condition I or II, and at least one axial portion of each of the first axial side portion and the second axial side portion satisfies condition III. Preferably, at least one axial portion of the central rib or each central rib satisfies condition I, and at least one axial portion of each of the first axial side portion and the second axial side portion satisfies condition III.

[0059] During the acceleration phase, the load on the front of the vehicle becomes less, so the axial central portion will come into contact with the ground on which it is driven, while the first and second axial side portions come into contact with the ground to a lesser extent (if at all). In order to reduce the noise emitted during this acceleration phase as much as possible, especially in the case of front-wheel drive vehicles, it is therefore preferred to make the axial central portion as quiet as possible, so that one or more central ribs have a small number of transverse cutouts or even no transverse cutouts.

[0060] Advantageously, in order to avoid as much as possible the superposition of the noise spectrum originating from the incision excitation with the noise spectrum originating from the mechanical structure, the depth of the central rib or each central rib or the axial side portion or each axial side portion is greater than or equal to 20% of the tread pattern height and the axial length is greater than or equal to 20% of the axial width of the central rib or each central rib or the axial side portion or each axial side portion and all N transverse incisions that meet condition II are preferably arranged so that πx OD / N ≥ 60 mm, and more preferably πx OD / N ≥ 80 mm.

[0061] In a preferred embodiment, the depth of the central rib or each central rib or the axial side portion or each axial side portion is greater than or equal to 20% of the tread pattern height and the axial length is greater than or equal to 20% of the axial width of the central rib or each central rib or the axial side portion or each axial side portion and all N transverse cuts satisfying condition III are arranged so that πx OD / N ≥ 10 mm, preferably πx OD / N ≥ 15 mm.

[0062] Limiting the number of transverse cuts in the tire contact patch avoids excessively reducing the area of ​​contact between the tread and the ground, thus avoiding excessive increase in the pressure exerted by the ground on each corner forming the edge of the transverse cut. This avoids compromising the grip on dry ground, since grip is an inverse function of the pressure exerted by the ground on the tread.

[0063] Advantageously, in order to avoid as much as possible the superposition of the noise spectrum originating from the incision excitation with the noise spectrum originating from the mechanical structure, the depth of the central rib or each central rib or the axial side portion or each axial side portion is greater than or equal to 20% of the tread pattern height and the axial length is greater than or equal to 20% of the axial width of the central rib or each central rib or the axial side portion or each axial side portion and all N transverse incisions that meet condition III are preferably arranged so that πx OD / N≤22mm, and more preferably πx OD / N≤20mm.

[0064] Very advantageously, in order to limit as much as possible the external noise emitted by the parts that do not satisfy any of the conditions I, II and III, the axial width of all axial parts of the central rib or each central rib and the first axial side part and the second axial side part that respectively only satisfy one of the conditions I, II, III is greater than or equal to 80%, preferably 90%, of the axial width of the central rib or each central rib and the first axial side part and the second axial side part.

[0065] As mentioned above, in order to minimize the diversity of the transition area by reducing the number of conditions satisfied on the same central rib or the same axial side portion, the central rib or each central rib or the first axial side portion or the second axial side portion includes several axial portions that respectively satisfy only one of the conditions I, II, and III, and all axial portions of the central rib or each central rib or the first axial side portion or the second axial side portion only satisfy one of the conditions I, II, and III.

[0066] As described above, in order to minimize the number of transition areas by minimizing the number of axial portions that do not satisfy any of the conditions I, II and III and are axially inserted between different axial portions that satisfy a single condition I, II, III, the central rib or each central rib and the first axial side portion and the second axial side portion each include the following axial portions: the axial portion only satisfies one of the conditions I, II, III and the axial width is greater than or equal to 70%, preferably 80%, and more preferably 90% of the axial width of the central rib or each central rib and the first axial side portion and the second axial side portion respectively.

[0067] In an advantageous embodiment, the ratio of the axial width of the central portion to the axial width of each of the first and second axial side portions is greater than or equal to 3.0, preferably in the range of 3.0 to 5.0, more preferably in the range of 4.0 to 4.5.

[0068] In this embodiment, the axial central portion is the portion having the largest axial width relative to the first axial side portion and the second axial side portion. This embodiment is particularly advantageous when the rib or each rib satisfies condition I or II, whereby the smaller the axial width of the axial central portion, the greater the extent to which the noise generated by the transverse cutout can be reduced.

[0069] Advantageously, the axial width of the axially central portion is greater than or equal to 50% of the axial width of the tread surface of a new tire, preferably greater than or equal to 60% of the axial width of the tread surface of a new tire. Advantageously, the axial width of the axially central portion is less than or equal to 80% of the axial width of the tread surface of a new tire, preferably less than or equal to 70% of the axial width of the tread surface of a new tire.

[0070] Advantageously, the first axial side portion and the second axial side portion each have an axial width less than or equal to 25% of the axial width of the tread surface of a new tire, preferably less than or equal to 20% of the axial width of the tread surface of a new tire. Advantageously, the first axial side portion and the second axial side portion each have an axial width greater than or equal to 5% of the axial width of the tread surface of a new tire, preferably greater than or equal to 10% of the axial width of the tread surface of a new tire.

[0071] According to the advantageous characteristics of each main circumferential groove:

[0072] - The depth of each main circumferential groove ranges from 4.0 mm to the tread pattern height, preferably ranges from 5.0 mm to the tread pattern height, and more preferably ranges from 5.5 mm to the tread pattern height.

[0073] - The width of each main circumferential groove is greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, more preferably greater than or equal to 8.0 mm, still more preferably in the range of 8.0 mm to 15.0 mm.

[0074] Advantageously, the first axial side portion and the second axial side portion each comprise a transverse cut extending axially from the axially outer end to the axially inner end, at least 50%, preferably at least 75%, and even more preferably each of the transverse cuts of the first axial side portion and the second axial side portion being at least partially blocked by a connecting bridge connecting the leading edge face and the trailing edge face and forming the axial inner end of the transverse cut. In order to take into account only those transverse cuts that contribute most to the noise, the above characteristics preferably apply to all N transverse cuts having a depth greater than or equal to 20% of the tread pattern height and an axial length greater than or equal to 20% of the axial width of the first axial side portion and the second axial side portion, respectively.

[0075] In other words, the connecting bridge constitutes a part of the axial outer side surface of the first main circumferential groove or the second main circumferential groove. In addition, due to the presence of the connecting bridge, the air transmission between the transverse cutout and the main circumferential groove in the axial central part is limited or even completely eliminated, so the acoustic resonance of the potential air column that may be established between the transverse cutout and the circumferential groove is also limited.

[0076] Even more advantageously, when the transverse cut enters the contact patch (where the tyre comes into contact with the ground on which it runs), the connecting bridges are arranged in such a way as to completely block the communication between the transverse cut and the first or second main circumferential grooves. This eliminates any risk of acoustic resonance of the air column between the transverse cut and the circumferential grooves.

[0077] According to the advantageous features of each transverse incision:

[0078] - the depth of each transverse cut is in the range of 2.0 mm to the tread pattern height, preferably in the range of 4.0 mm to the tread pattern height, still more preferably in the range of 5.0 mm to the tread pattern height,

[0079] - The width of each transverse cut is less than or equal to 2.0 mm, preferably in the range of 0.5 mm to 2.0 mm.

[0080] Advantageously, at least one transverse cutout of at least one of the first and second axial side portions, preferably at least 25%, more preferably at least 40% of the transverse cutouts of at least one of the first and second axial side portions, comprising a main portion and a supplementary portion separated from each other by a discontinuity in curvature of each side, satisfies:

[0081] - the main part extends over a main curve length which is strictly greater than 50% of the total curve length of the transverse incision,

[0082] The complementary portion extends over a complementary curvilinear length which is strictly less than 50% of the total curvilinear length of the transverse cutout, the complementary portion being axially arranged outside the main portion and having a width greater than that of the main portion.

[0083] These additional sections allow effective water drainage, resulting in better grip on wet surfaces.

[0084] According to a preferred feature of the tire, the surface area void fraction of the tread ranges from 27% to 45%, preferably from 30% to 40%.

[0085] According to another preferred characteristic of the tire, the volume void fraction of the tread ranges from 17% to 35%, preferably from 20% to 30%.

[0086] Such surface area porosity and volume porosity ensure effective water drainage under driving conditions on wet surfaces.

[0087] Preferably, the surface area void fraction of each of the first axial side portion and the second axial side portion is in the range of 20% to 30%.

[0088] Again preferably, the first axial side portion and the second axial side portion each have a volume void fraction in the range of 5% to 10%.

[0089] Preferably, the surface area void fraction of the axially central portion is in the range of 35% to 45%.

[0090] Again preferably, the volume void fraction of the axially central portion ranges from 25% to 35%.

[0091] Preferably, the or each central rib has a surface area void fraction in the range 5% to 10%.

[0092] Again preferably, the or each central rib has a volume void fraction in the range 0.5% to 5%, preferably in the range 0.5% to 2%.

[0093] Advantageously, the ratio of the surface area void fraction of the or each central rib to the surface area void fraction of each of the first and second axial side portions is less than or equal to 0.35, preferably less than or equal to 3.0, more preferably in the range 0.10 to 0.30.

[0094] Advantageously again, the ratio of the volume void fraction of the or each central rib to the void fraction of each of the first and second axial side portions is less than or equal to 0.20, preferably less than or equal to 0.15, more preferably in the range 0.10 to 0.15.

[0095] The surface area void ratio of a tread, a portion of a tread, or a rib is the ratio of:

[0096] - the difference between the total surface area AT of the contact patch of the tread, part of the tread or of a rib where the tyre comes into contact with the smooth ground, such as a sheet of glass, and the contact area AC of the elements of the tread, part of the tread or of the rib which come into contact with the ground during driving, of the tyre when new, inflated to nominal pressure and under nominal load, and

[0097] The total surface area AT of the contact patch where the tire comes into contact with a smooth ground surface, such as a glass sheet, of the tread, a part of the tread or a rib of the tire, when new and inflated to nominal pressure and under nominal load.

[0098] The volume void fraction of the tread, a portion of the tread or a rib is the ratio of the total volume of the cuts in the tread, a portion of the tread or a rib of a new tire to the total volume of the tread, a portion of the tread or a rib of the same new tire but without any cuts. The tread is bounded axially by two planes perpendicular to the axis of rotation of the tire and passing through the axial edges of the tread surface. A portion of the tread or a rib is bounded axially by two planes perpendicular to the axis of rotation of the tire and passing through the ends of the axial edges of the portion or rib. The tread, a portion of the tread or a rib is bounded radially by the tread surface and a curve parallel to the tread surface of the new tire and passing through the radially innermost point of the deepest cut in the tread of the new tire.

[0099] To determine the surface area void fraction, the nominal load is equal to 80% of the load rating given by the 2019 European Tire and Rim Technical Organization or "ETRTO" standard and the nominal pressure is equal to 2.5 bar.

[0100] In an advantageous embodiment, the axial central portion comprises at least a third main circumferential groove and at least a first central rib and a second central rib and is arranged such that:

[0101] - the first central rib is axially located between the first main circumferential groove and the third main circumferential groove,

[0102] The second central rib is axially interposed between the second main circumferential groove and the third main circumferential groove.

[0103] Thus, for a given axial width of the axially central portion, by increasing the number of central ribs, drainage is improved over the entire axial width of the tread.

[0104] In an even more preferred embodiment, the axial central portion comprises the third and fourth main circumferential grooves and at least the first, second and third central ribs and is arranged such that:

[0105] - the first central rib is axially located between the first main circumferential groove and the third main circumferential groove,

[0106] - the second central rib is axially interposed between the third main circumferential groove and the fourth main circumferential groove, and

[0107] The third central rib is axially interposed between the fourth main circumferential groove and the second main circumferential groove.

[0108] Drainage is further improved due to the presence of three central ribs.

[0109] In this even more preferred embodiment:

[0110] - a first central rib extending axially from the axially inner edge of the first main circumferential groove to the axially outer edge of the third main circumferential groove,

[0111] - the second central rib extends axially from the axially outer edge of the third main circumferential groove to the axially inner edge of the fourth main circumferential groove, and

[0112] The third central rib extends axially from the axially outer edge of the fourth main circumferential groove to the axially inner edge of the second main circumferential groove.

[0113] In the aforementioned embodiment, the axial width of the central rib or each central rib is less than or equal to 30% of the axial width of the axial central portion, preferably less than or equal to 25% of the axial width of the axial central portion. Therefore, regardless of the number of central ribs, by reducing the axial width of each central rib, drainage of each central rib can be promoted.

[0114] In order to have sufficient tread surface area to reduce the local pressure exerted by the ground on the tire and thus ensure good grip on dry ground, the central rib or each central rib has a sufficient axial width greater than or equal to 10% of the axial width of the axial central portion, preferably greater than or equal to 15% of the axial width of the axial central portion.

[0115] In a highly preferred embodiment the or each central rib has an axial width in the range 20mm to 40mm, preferably 25mm to 35mm.

[0116] In an embodiment of improving the grip on wet ground while generating little or no additional noise in the axially central portion and without deteriorating the performance of the tyre, the central rib or at least one central rib, preferably each central rib, comprises at least one additional circumferential cutout, the or each additional circumferential cutout:

[0117] - arranged axially between two circumferential grooves, the or each central rib being interposed between the two circumferential grooves, and

[0118] The depth is strictly less than 50% of the tread pattern height, preferably less than or equal to 30% of the tread pattern height, more preferably ranging from 10% to 30% of the tread pattern height.

[0119] In particular, due to its circumferential orientation and therefore the circumferential orientation of the side edges of the or each additional circumferential cut, the or each additional circumferential cut contributes little or nothing to the noise originating from the cut excitation, since the corners of the or each additional circumferential cut do not hit the ground when the tire is running.

[0120] Due to the void volume created, the or each additional circumferential cutout is able to store water when driving on wet ground, thereby improving the grip on wet ground. Furthermore, each additional circumferential cutout divides the central rib in which the additional circumferential cutout is formed into two axial sections, each axial section being delimited by the main circumferential cutout on the one hand and the additional circumferential cutout on the other hand. As a result, the axial width of each axial section of the central rib is shorter than without the additional circumferential cutout, and the ability to drain water from the middle of each axial section to each main circumferential cutout and additional circumferential cutout is therefore greater.

[0121] Finally, since the depth is relatively small, the or each additional circumferential cut does not worsen the performance of the tyre, in particular in terms of lateral stiffness.

[0122] According to favorable features:

[0123] - the axial width of the or each additional circumferential cutout of the or each central rib is in the range of 4% to 15%, preferably 4% to 10% of the axial width of the or each central rib. In a highly preferred embodiment, the axial width of the or each additional circumferential cutout is in the range of 1.0 mm to 4.0 mm.

[0124] The or each additional circumferential cutout has a depth less than or equal to 3.0 mm, preferably in the range 1.0 mm to 3.0 mm.

[0125] By giving priority to additional circumferential cuts that are wider than they are deep, the axial width of each axial portion of the central rib arranged on either side of the additional circumferential cut is reduced, thereby improving the ability of the tyre to drain water from each main circumferential cut and the additional circumferential cut, the greater the axial width of the or each additional circumferential cut. However, this axial width must not be too large in order to have sufficient tread surface area to reduce the local pressure exerted by the ground on the tyre, thereby ensuring good grip on dry ground.

[0126] In an embodiment for improving grip on wet ground while generating little or no additional noise in the first axial side portion and without deteriorating the performance of the tire, the first axial side portion is identical to the axial central portion and comprises at least one additional circumferential cutout as follows:

[0127] - is arranged axially between the first circumferential groove and a first axial end of the tread, and

[0128] The depth is strictly less than 50% of the tread pattern height, preferably less than or equal to 30% of the tread pattern height, more preferably ranging from 10% to 30% of the tread pattern height.

[0129] Similarly, in order to improve the grip on wet ground, while generating little or no additional noise in the second axial side portion and without deteriorating the performance of the tyre, the second axial side portion, identical to the axial central portion and the first axial side portion, comprises at least one additional circumferential cutout as follows:

[0130] - is arranged axially between the second circumferential groove and the second axial end of the tread, and

[0131] The depth is strictly less than 50% of the tread pattern height, preferably less than or equal to 30% of the tread pattern height, more preferably ranging from 10% to 30% of the tread pattern height.

[0132] According to advantageous features, like the additional circumferential cutouts in the axial central part, the tyre's ability to shed water is improved while ensuring good grip on dry ground:

[0133] The or each additional circumferential cutout of the first axial side portion has an axial width in the range 3% to 15%, preferably 3% to 10%, of the axial width of the first axial side portion.

[0134] The or each additional circumferential cutout of the second axial side portion has an axial width in the range 3% to 15%, preferably 3% to 10%, of the axial width of the second axial side portion.

[0135] In a highly preferred embodiment:

[0136] - whether the additional circumferential cutout is formed in the first axial side portion or in the second axial side portion, the or each additional circumferential cutout has an axial width ranging from 1.0 mm to 4.0 mm,

[0137] Whether the additional circumferential cutout is made in the first axial side portion and / or in the second axial side portion, the or each additional circumferential cutout has a depth less than or equal to 3.0 mm, preferably ranging from 1.0 mm to 3.0 mm.

[0138] In an embodiment capable of reducing the pressure on the corners forming the cutout edges and thus improving the grip on dry ground, at least one main circumferential groove has a chamfer. In other words, each main circumferential groove (including the central rib or one central rib in between) is axially delimited by an axially inner side surface and an axially outer side surface, which delimit the main circumferential groove axially towards the inside and towards the outside and are joined together by a bottom surface, which delimits the main circumferential groove radially towards the inside, and at least one circumferential groove (preferably each main circumferential groove) is arranged so that at least one of the axially inner side surface and the axially outer side surface is connected to at least one of the axially inner edge and the axially outer edge of the main circumferential groove by a chamfer, preferably the axially inner side surface and the axially outer side surface are each connected to the axially inner edge and the axially outer edge of each main circumferential groove respectively by a chamfer.

[0139] The chamfer on the circumferential cutout can be a straight chamfer or a round chamfer. A straight chamfer is formed by a plane that is inclined relative to the axially inner side surface and the axially outer side surface and continues until the axially inner edge or the axially outer edge that axially delimits the circumferential cutout. A round chamfer is formed by a curved surface that merges tangentially with the axially inner side surface or the axially outer side surface that it continues. The chamfer on the circumferential cutout is characterized in that the height and width are respectively equal to the radial distance and the axial distance between the common point of the axially inner side surface or the axially outer side surface to which the chamfer extends and the axially inner edge or the axially outer edge that axially delimits the circumferential cutout.

[0140] In order to improve the grip on dry ground, if conditions II and / or III are met, at least 50%, preferably at least 75%, and more preferably each of the transverse cuts has a chamfer. In other words, each transverse cut is delimited radially by a leading edge face and a trailing edge face, which delimit the transverse cut in the circumferential direction and are connected to each other by a bottom face, which delimits the transverse cut radially toward the inside, and at least 50%, preferably at least 75%, and more preferably each of the transverse cuts is arranged so that at least one of the leading edge face and the trailing edge face is connected to at least one of the front edge and the rear edge of the circumferential cut by a chamfer, preferably the leading edge face and the trailing edge face are each connected to the respective front edge and the rear edge of each circumferential cut by a chamfer.

[0141] The chamfer on the transverse cutout can be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a plane that is inclined relative to the leading edge face and the trailing edge face and continues until the leading edge or the trailing edge that circumferentially delimits the transverse cutout. A rounded chamfer is formed by a curved surface that merges tangentially with the leading edge face or the trailing edge face that it continues. The chamfer on the transverse cutout 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 edge face or the trailing edge face between the common point of the leading edge face or the trailing edge face to which the chamfer extends and the leading edge or the trailing edge that circumferentially delimits the transverse cutout.

[0142] 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 inside the tread. The tyre also comprises a carcass reinforcement anchored in each bead and extending in each sidewall and radially inside the crown.

[0143] In conventional manner, the crown reinforcement comprises at least one crown layer containing reinforcing elements. These reinforcing elements are preferably textile or metal thread-like elements.

[0144] In an embodiment capable of obtaining the properties of a tyre known as a radial tyre as defined by ETRTO, the carcass reinforcement comprises at least one carcass layer, the or each carcass layer comprising carcass filamentary reinforcing elements, each carcass filamentary reinforcing element extending substantially in a main direction making an angle with the circumferential direction of the tyre having an absolute value ranging from 80° to 90°. BRIEF DESCRIPTION OF THE DRAWINGS

[0145] The invention will be better understood on reading the following description given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0146] - Figure 1 is a meridian cross-sectional plane view parallel to the axis of rotation of the tire according to a first embodiment of the present invention,

[0147] - Figure 2 for Figure 1 sectional view of a tire of , showing the arrangement of the filamentary reinforcing elements in and under the crown,

[0148] - Figure 3 for Figure 1 A three-dimensional view of the tire tread.

[0149] - Figure 4 for Figure 3 A meridian cross-sectional plane view of the tread parallel to the tire rotation axis,

[0150] - Figure 5 for Figure 4 Detailed view of region V,

[0151] - Figure 6 for Figure 3 Detailed view of Area VI,

[0152] - Figure 7 for Figure 6 Detail of Region VII,

[0153] - Figure 8 for Figure 6 Detail of Region VIII,

[0154] - Fig. 9 for Figure 1 A schematic diagram of a tire, and

[0155] - Figures 10 to 13 The tires according to the second, third, fourth and fifth embodiments of the present invention are respectively Fig. 9 Similar pictures. DETAILED DESCRIPTION

[0156] In the figures relating to the tire, reference frames X, Y, Z are shown, corresponding respectively to the usual axial direction (Y), radial direction (Z) and circumferential direction (X) of the tire.

[0157] In the following description, except for the volume void fraction and surface area void fraction measurements, all other measurements are performed on an unloaded and uninflated tire.

[0158] Figure 1 A tyre according to the invention is shown, indicated overall with the reference 10. The tyre 10 has a generally toroidal 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 245 / 45R18. In the various figures, the tyre 10 is depicted as new, that is to say when it has not yet been driven. The outer diameter OD of the tyre 10 is equal to 678 mm.

[0159] The tyre 10 comprises a crown 12 including a tread 14 intended to come into contact with the ground when running, and a crown reinforcement 16 extending in the crown 12 in a circumferential direction X. The tyre 10 also comprises an airtight layer 18, airtight to the inflation gas, intended to delimit a closed internal cavity with a mounting support for the tyre 10 when the tyre 10 has been mounted on such a mounting support, such as a rim.

[0160] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22. The working reinforcement 16 comprises at least one working layer, in this case two working layers 24, 26. In this particular case, the working reinforcement 16 consists of two working layers 24, 26. The radially inner working reinforcement 24 is arranged radially on the inside of the radially outer working layer 26.

[0161] The hoop reinforcement 22 comprises at least one hoop layer, in this case one hoop layer 28. The hoop reinforcement 22 consists in this case of a hoop layer 28.

[0162] The crown reinforcement 16 is radially covered by the tread 14. In this case, the hoop reinforcement 22, in this case the hoop layer 28, is arranged radially on the outside of the working reinforcement 20 and is therefore radially interposed between the working reinforcement 20 and the tread 14. Preferably, it is envisaged that the hoop reinforcement 22 has an axial width at least as great as the axial width of the working reinforcement 20, in this particular case Figure 1 In the embodiment shown, the hoop reinforcement 22 has an axial width that is greater than the axial width of the working reinforcement 20 .

[0163] The tire 10 comprises two sidewalls 30 extending the crown 12 radially inwardly. The tire 10 also has two beads 32 located radially inside the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown 12.

[0164] The tire 10 comprises a carcass reinforcement 34 anchored in each bead 32 and turned up in this case around the bead wire 33. The carcass reinforcement 34 is in each sidewall 30 and extends radially inside the crown 12. The crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass layer, in this case a single carcass layer 36. In this particular case, the carcass reinforcement 34 consists of a single carcass layer 36.

[0165] Each working layer 24, 26, the hoop layer 28 and the carcass layer 36 comprises an elastomeric matrix in which one or more filamentary reinforcing elements of the corresponding layer are embedded. Figure 2 Describe these layers.

[0166] Hoop reinforcement 22 (in this case, hoop layer 28) is axially defined by two axial edges 28A, 28B of hoop reinforcement 22. Hoop reinforcement 22 comprises one or more hoop filamentary reinforcing elements 280, which are spirally wound circumferentially to extend axially from the axial edge 28A of hoop layer 28 to another axial edge 28B along the main direction D0 of each hoop filamentary reinforcing element 280. Main direction D0 forms an angle AF whose absolute value is less than or equal to 10 °, preferably less than or equal to 7 °, more preferably less than or equal to 5 ° with the circumferential direction X of tire 10. In this case, AF=-5 °. Hoop layer 28 has a density of 98 hoop filamentary reinforcing elements per decimeter, which is measured perpendicular to direction D0.

[0167] The radially inner working layer 24 is axially bounded by two axial edges 24A, 24B. The radially inner working layer 24 comprises working filamentary reinforcing elements 240, which extend axially from the axial edge 24A to the other axial edge 24B in a manner substantially parallel to each other along the main direction D1. Similarly, the radially outer working layer 26 is axially bounded by two axial edges 26A, 26B. The radially outer working layer 26 comprises working filamentary reinforcing elements 260, which extend axially from the axial edge 26A to the other axial edge 26B in a manner substantially parallel to each other along the main direction D2. The main direction D1 in which each working filamentary reinforcing element 240 of the radially inner working layer 24 extends and the main direction D2 in which each working filamentary reinforcing element 260 of the other radially outer working layer 26 extends form angles AT1 and AT2 with the circumferential direction X of the tire 10, respectively, and the orientations of the angles AT1 and AT2 are opposite. Each main direction D1, D2 forms an angle AT1, AT2 with the circumferential direction X of the tyre 10, respectively, of absolute value strictly greater than 10°, preferably ranging from 15° to 50°, more preferably ranging from 15° to 30°. In this case, AT1 = -26° and AT2 = +26°.

[0168] The carcass layer 36 is axially delimited by two axial edges 36A, 36B. The carcass layer 36 comprises carcass filamentary reinforcing elements 360 extending axially from an axial edge 36A of the carcass layer 36 to another axial edge 36B along a main direction D3, the main direction D3 forming an angle AC with the circumferential direction X of the tire 10 having an absolute value greater than or equal to 60°, preferably ranging from 80° to 90°, and in this case AC=+90°.

[0169] Each hoop filamentary reinforcing element 280 generally comprises two multifilamentary strands, and each multifilamentary strand is made up of the spinning of aliphatic polyamide (in this case nylon) monofilament equal to 140tex by thread count, and these two multifilamentary strands are twisted with 250 turns / meter spirally in one direction, and then twisted with 250 turns / meter spirally in the opposite direction.These two multifilamentary strands are spirally wound around each other.As an alternative, hoop filamentary reinforcing element 280 can be used, it comprises a multifilamentary strand made up of the spinning of aliphatic polyamide (in this case nylon) monofilament equal to 140tex by thread count and a multifilamentary strand made up of the spinning of aromatic polyamide (in this case aramid) monofilament equal to 167tex by thread count, and these two multifilamentary strands are twisted with 290 turns / meter spirally in one direction, and then twisted with 290 turns / meter spirally in the opposite direction.These two multifilamentary strands are spirally wound around each other. This variant results in AT1 = -29° and AT2 = +29°.

[0170] Each working filamentary reinforcing element 180 is an assembly with two steel monofilaments wound in a spiral with a pitch of 14mm, and the diameter of each steel monofilament is equal to 0.30mm. As an alternative, an assembly of six steel monofilaments with a diameter equal to 0.23mm can also be used, and the six steel monofilaments include an inner layer of two monofilaments wound in a spiral with a pitch of 12.5mm in a first direction (e.g., Z direction), and an outer layer of four monofilaments wound in a spiral around the inner layer in a second direction (e.g., S direction) opposite to the first direction with a pitch of 12.5mm. In another alternative, each working filamentary reinforcing element 180 is composed of a steel monofilament with a diameter equal to 0.30mm. More generally, the diameter range of the steel monofilament is 0.25mm to 0.32mm.

[0171] Each carcass filamentary reinforcing element 340 generally comprises two multifilament strands, each of which is made of spinning of polyester (PET in this case) monofilaments, which are twisted together in one direction with 240 turns / m spirally, and then twisted together in the opposite direction with 240 turns / m spirally. These multifilament strands each have a thread count equal to 220 tex. In other variants, a thread count equal to 144 tex and a twist equal to 420 twists / m or a thread count equal to 334 tex and a twist equal to 270 twists / m can be used.

[0172] refer to Figure 1 , Figure 3 and Figure 4 , the tread 14 comprises a tread surface 38 through which the tread 14 comes into contact with the ground. The tread surface 38 is intended to come into contact with the ground when the tire 10 is running along the ground and is axially delimited by a first axial edge 41 and a second axial edge 42 passing through each point N arranged on either side of the midplane M, wherein for each point N, the angle between a tangent T to the tread surface 38 and a straight line R parallel to the axial direction Y and passing through said point is equal to 30°.

[0173] refer to Figure 1 as well as Figures 3 to 5 The tread 14 includes an axially central portion P0 and a first axial side portion P1 and a second axial side portion P2, wherein the first axial side portion P1 and the second axial side portion P2 are axially arranged outside the axially central portion P0 and are axially located on both sides of the axially central portion P0 relative to the midplane M of the tire 10.

[0174] The axial width L0 of the axial center portion P0 is greater than or equal to 50% of the axial width L of the tread surface 38 of the new tire 10, preferably greater than or equal to 60% of the axial width L of the tread surface 38 of the new tire 10, and less than or equal to 80% of the axial width L of the tread surface 38 of the new tire 10, preferably less than or equal to 70% of the axial width L of the tread surface 38 of the new tire 10.

[0175] The axial widths L1 and L2 of the first axial side portion P1 and the second axial side portion P2 are respectively less than or equal to 25% of the axial width L of the tread surface 38 of the new tire 10, preferably less than or equal to 20% of the axial width L of the tread surface 38 of the new tire 10, and greater than or equal to 5% of the axial width L of the tread surface 38 of the new tire 10, preferably greater than or equal to 10% of the axial width L of the tread surface 38 of the new tire 10.

[0176] The ratio of the axial width L0 of the central portion P0 to the axial widths L1 and L2 of the first and second axial side portions P1 and P2 is greater than or equal to 3.0, preferably in the range of 3.0 to 5.0, and more preferably in the range of 4.0 to 4.5.

[0177] In this case, L0 = 140 mm, L1 = L2 = 33 mm and L = 206 mm.

[0178] The axially central portion includes main circumferential grooves, including a first main circumferential groove, a second main circumferential groove, a third main circumferential groove, and a fourth main circumferential groove, respectively indicated by reference numerals 52, 54, 56, and 58. The first groove 52 and the second groove 54 are arranged one on each side of the midplane M of the tire 10 in the axial direction, and are the main circumferential grooves closest to the outer side of the tread 14 in the axial direction.

[0179] Reference Figures 3 to 5 , at a radial dimension equal to the radial dimension of the tread surface 38, the first main circumferential groove 52, the second main circumferential groove 54, the third main circumferential groove 56 and the fourth main circumferential groove 58 are each axially bounded by an axially outer edge represented by reference numerals 521, 541, 561, 581, respectively, and an axially inner edge represented by reference numerals 522, 542, 562, 582, respectively.

[0180] refer to Figure 4 and Figure 5 , at a radial dimension inside the radial dimension of the tread surface 38, each main circumferential groove 52, 54, 56, 58 is axially bounded by an axially inner side surface Fr1 and an axially outer side surface Fr2 that axially bound each main circumferential groove 52, 54, 56, 58. Each main circumferential groove 52, 54, 56, 58 is radially bounded toward the inside by a bottom surface Frd.

[0181] Each main circumferential groove 52, 54, 56, 58 has a chamfer, that is, each main circumferential groove 52, 54, 56, 58 is arranged so that at least one (in this case each) of the axial inner side surface Fr1 and the axial outer side surface Fr2 is connected to the respective axial inner edge 522, 542, 562, 582 and axial outer edge 521, 541, 561, 581 of the main circumferential groove 52, 54, 56, 58 by a chamfer Cf.

[0182] The depth of each main circumferential groove 52, 54, 56, 58 is represented by reference numerals Hr2, Hr4, Hr6, Hr8, respectively, and ranges from 4.0 mm to the tread pattern height Hs, preferably ranges from 5.0 mm to the tread pattern height Hs, and more preferably ranges from 5.5 mm to the tread pattern height Hs. Each depth Hr2, Hr4, Hr6, Hr8 is greater than or equal to 50% of the tread pattern height Hs. In this case, Hs=Hr6=Hr8=6.5 mm and Hr2=Hr4=6.0 mm.

[0183] The width of each main circumferential groove 52, 54, 56, 58 is represented by reference numerals Lr2, Lr4, Lr6, Lr8, respectively, and is greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, more preferably greater than or equal to 8.0 mm, and more preferably in the range of 8.0 mm to 15.0 mm. In this case, Lr2 = Lr4 = 10.0 mm and Lr6 = Lr8 = 12.5 mm.

[0184] The axial center portion P0 axially extends from the axial outer edge 521 of the first main axial groove 52 to the axial outer edge 541 of the second main circumferential groove 54 .

[0185] The axial central portion P0 includes a first central rib, a second central rib, and a third central rib, respectively indicated by reference numerals 62, 64, 66. Each central rib 62, 64, 66 is axially bounded by two main circumferential grooves (in this case, two of the first main circumferential groove 52, the second main circumferential groove 54, the third main circumferential groove 56, and the fourth main circumferential groove 58).

[0186] The first central rib 62 is arranged so that it is axially interposed between the first main circumferential groove 52 and the third main circumferential groove 56. In this case, the first central rib 62 extends axially from the axial inner edge 522 of the first main circumferential groove 52 to the axial outer edge 561 of the third main circumferential groove 56.

[0187] The second central rib 64 is arranged so that it is axially interposed between the third main circumferential groove 56 and the fourth main circumferential groove 58. In this case, the second central rib 64 extends axially from the axial inner edge 562 of the third main circumferential groove 56 to the axial inner edge 582 of the fourth main circumferential groove 58.

[0188] The third central rib 66 is arranged so that it is axially interposed between the fourth main circumferential groove 58 and the second main circumferential groove 54. In this case, the third central rib 66 extends axially from the axial outer edge 581 of the fourth circumferential groove to the axial inner edge 542 of the second main circumferential groove 54.

[0189] The axial width of each central rib 62, 64, 66 is represented by reference numerals Ln2, Ln4, Ln6, respectively, and is less than or equal to 30% of the axial width L0 of the axial central portion P1, preferably less than or equal to 25% of the axial width L0 of the axial central portion P1, and greater than or equal to 10% of the axial width L0 of the axial central portion P1, preferably greater than or equal to 15% of the axial width L0 of the axial central portion P1. Each axial width Ln2, Ln4, Ln6 ranges from 20 mm to 40 mm, preferably from 25 mm to 35 mm. In this case, Ln2 = Ln4 = Ln6 = 29.5 mm.

[0190] The axial central portion P0 includes at least one additional circumferential cutout formed in one of the central ribs 62, 64, 66. In this case, each central rib 62, 64, 66 includes an additional circumferential cutout 72, 74, 76, respectively. Each additional circumferential cutout 72, 74, 76 is arranged axially between two circumferential grooves 52 and 56, 56 and 58, 58 and 54, respectively, and the central ribs 62, 64, 66 are each between two circumferential grooves 52 and 56, 56 and 58, 58 and 54.

[0191] The depth of each additional circumferential cutout 72, 74, 76 is strictly less than 50% of the tread pattern height Hs, preferably less than or equal to 30% of the tread pattern height Hs, and more preferably in the range of 10% to 30% of the tread pattern height Hs. Each additional circumferential cutout 72, 74, 76 has an axial width Lc2, Lc4, Lc6, respectively, ranging from 4% to 15% of each axial width Ln2, Ln4, Ln6, preferably 4% to 10%. Each axial width Lc2, Lc4, Lc6 ranges from 1.0mm to 4.0mm, in which case Lc2=Lc4=Lc6=2.0mm. Each additional circumferential cutout 72, 74, 76 has a depth Hc2, Hc4, Hc6 less than or equal to 3.0mm, preferably in the range of 1.0mm to 3.0mm, in which case Hc2=Hc4=Hc6=1.0mm.

[0192] refer to Fig. 9 , each central rib 62, 64, 66 comprises an axial portion P62, P64, P66, respectively, in this case consisting of the respective axial portions P62, P64, P66. The axial width of each axial portion P62, P64, P66 is equal to the respective axial widths Ln2, Ln4 and Ln6. Each axial portion P62, P64, P66 does not include a transverse cut having a depth greater than or equal to 20% of the tread pattern height Hs and an axial length greater than or equal to 20% of the axial widths Ln2, Ln4 and Ln6 of each central rib 62, 64, 66, so that each of these axial portions P62, P64, P66 satisfies only one of the conditions I, II, III, in this case satisfying condition I. The axial width of all axial portions P62, P64, P66 (in this case the axial width of each axial portion P62, P64, P66 of each central rib 62, 64, 66) is greater than or equal to 70%, preferably 80%, more preferably 90% of the axial width of each central rib 62, 64, 66, and in this case, is equal to 100% of each axial width Ln2, Ln4, Ln6.

[0193] refer to Figure 3 The first axial side portion P1 is arranged such that it extends axially from the first axial edge 41 of the tread surface 38 to the axially outer edge 521 of the first main circumferential groove 52 .

[0194] The second axial side portion P2 is arranged such that it extends axially from the second axial edge 42 of the tread surface 38 to the axially outer edge 541 of the second main circumferential groove 54 .

[0195] refer to Figures 4 to 6 , the first axial side portion P1 and the second axial side portion P2 each include additional circumferential cutouts 82, 84 formed therein, respectively. The additional circumferential cutout 82 is axially arranged between the first circumferential groove 52 and the first axial edge 41 of the tread surface 38. The additional circumferential cutout 84 is axially arranged between the second circumferential groove 54 and the second axial edge 42 of the tread surface 38.

[0196] The depth of each additional circumferential cut 82, 84 is strictly less than 50% of the tread pattern height Hs, preferably less than or equal to 30% of the tread pattern height Hs, and more preferably in the range of 10% to 30% of the tread pattern height Hs. Each additional circumferential cut 82, 84 has an axial width LI2, LI4, respectively, ranging from 3% to 15% of each axial width L1, L2, preferably 3% to 10%. Each axial width LI2, LI4 ranges from 1.0mm to 4.0mm, in which case LI2=LI4=2.0mm. Each additional circumferential cut 82, 84 has a depth HI2, HI4, respectively, less than or equal to 3.0mm, preferably in the range of 1.0mm to 3.0mm, in which case HI2=HI4=1.0mm.

[0197] refer to Figure 6 , each axial side portion P1, P2 comprises a transverse cutout 90, 90', respectively, whose depth is greater than or equal to 20% of the tread pattern height Hs. In this particular case, the depth Ht of all transverse cutouts 90, 90' of each axial side portion P1, P2 is greater than or equal to 20%, preferably 30%, more preferably 40% of the tread pattern height Hs. The depth Ht of each transverse cutout 90, 90' ranges from 2.0 mm to the tread pattern height Hs, preferably ranges from 4.0 mm to the tread pattern height Hs, and more preferably ranges from 5.0 mm to the tread pattern height Hs, where Ht=6.0 mm.

[0198] refer to Figure 7 and Figure 8 , at a radial dimension equal to the radial dimension of the tread surface 38, each transverse cut 90, 90' is circumferentially bounded by a front edge 901 and a rear edge 902. At a dimension radially inside the radial dimension of the tread surface 38, each transverse cut 90, 90' is circumferentially bounded by a leading edge face Ft1 and a trailing edge face Ft2. Each transverse cut 90, 90' is bounded radially toward the inside by a bottom face Ftd. Each transverse cut 90, 90' has a chamfer, that is, each transverse cut 90, 90' is arranged so that the leading edge face Ft1 and the trailing edge face Ft2 are each connected to the respective leading edge 901 and the trailing edge 902 of each transverse cut 90, 90' by a chamfer Cf. Each transverse cutout 90 , 90 ′ extends axially from an axially outer end E1 to an axially inner end E2 , defining an overall curvilinear length TI of each transverse cutout 90 , 90 ′ and an axial length La, La′ of each transverse cutout 90 , 90 ′.

[0199] Among the transverse cuts 90, 90' having a depth greater than or equal to 20% of the tread pattern height Hs, a distinction is made between four series of transverse cuts 90 including transverse cuts 92, 94, 96, 98 formed in the first axial side portion P1 and three series of transverse cuts 90' including transverse cuts 92', 94', 96' formed in the second axial side portion P2. These cuts have different widths and are arranged irregularly in the circumferential direction to avoid whining sounds while also maintaining the uniformity of the tire. Each transverse cut 90, 90' has a width less than or equal to 2.0 mm, preferably in the range of 0.5 mm to 2.0 mm. Therefore, the width Lt2, Lt4, Lt6, Lt8, Lt2', Lt4', Lt6' of each transverse cutout 92, 94, 96, 98, 92', 94', 96' satisfies Lt2=Lt2'=1.2 mm, Lt4=Lt4'=Lt8=1.5 mm and Lt6=Lt6'=0.8 mm.

[0200] refer to Figure 3 , Figure 7 and Figure 8 The first axial side portion P1 includes transverse cuts 92, 94, 96, 98, each of which includes a main portion represented by reference numerals 921, 941, 961, 981 and a supplementary portion represented by reference numerals 922, 942, 962, 982, respectively, and the main portion and the supplementary portion are separated from each other by a curvature discontinuity portion 923, 943, 963, 983 of each leading edge face Ft1 and trailing edge face Ft2. Each supplementary portion 922, 942, 962, 982 is arranged axially outside each main portion 921, 941, 961, 981 and has a width Ls2, Ls4, Ls6, Ls8 greater than the width Lp2, Lp4, Lp6, Lp8 of each main portion 921, 941, 961, 981 (the width Lp2, Lp4, Lp6, Lp8 is equal here to each width Lt2, Lt4, Lt6, Lt8). Each main portion 921, 941, 961, 981 extends over a main curve length Tp that is strictly greater than 50% of the total curve length TI of each transverse cutout 92, 94, 96, 98. Each complementary portion 922 , 942 , 962 , 982 extends over a complementary curve length Tc that is strictly less than 50% of the total curve length TI of each transverse cutout 92 , 94 , 96 , 98 .

[0201] The axial length La of each transverse cutout 92, 94, 96, 98 is greater than or equal to 20%, preferably 30%, more preferably 50%, still more preferably 75% of the axial width L1 of the first axial side portion P1. In this case, La=42 mm.

[0202] Over the entire circumference of the tire 10, the number of transverse cuts 90 (including transverse cuts 92, 94, 96, 98) having a depth greater than or equal to 20% of the tread pattern height Hs and an axial length La greater than or equal to 20% of the axial width of the first axial side portion P1 is N = 125. In a variant of the first embodiment, N = 98.

[0203] like Figure 3 As can be seen in FIG. 1 , the second axial side portion P2 comprises transverse cutouts 92 ′, 94 ′, 96 ′, each of which comprises a main portion of a curvilinear length equal to the curvilinear length of the cutout.

[0204] The axial length La' of each transverse cutout 92', 94', 96' is greater than or equal to 20%, preferably 30%, more preferably 50%, still more preferably 75% of the axial width L2 of the second axial side portion P2. In this case, La2'=42 mm.

[0205] Over the entire circumference of the tire 10, the number of transverse cuts 90' (including transverse cuts 92', 94', 96') having a depth greater than or equal to 20% of the tread pattern height Hs and an axial length La' greater than or equal to 20% of the axial width of the second axial side portion P2 is N' = 125. In the above variant, N' = 98.

[0206] Each transverse cutout 90, 90' of the first axial side portion P1 and the second axial side portion P2 is at least partially closed by a connecting bridge 100 connecting the leading edge face Ft1 and the trailing edge face Ft2, the connecting bridge 100 forming the axial inner end E2 of each transverse cutout 90, 90'. When the transverse cutout enters the contact patch (in which the tire is in contact with the ground on which it runs), each connecting bridge 100 is arranged in such a way that the communication between each transverse cutout 90, 90' and the first main circumferential groove 52 or the second main circumferential groove 54 is completely blocked.

[0207] Therefore, reference Fig. 9 The first axial side portion P1 and the second axial side portion P2 each include a first axial portion P11, P21 including N, N' transverse cutouts 90, 90', respectively, and a second axial portion P12, P22 including a connecting bridge 100. The second axial portions P12, P22 are each axially arranged inside the first axial portions P11, P21, respectively.

[0208] The axial width of each axial portion P11, P21 is greater than or equal to 70%, preferably 80%, more preferably 90%, and here equal to 91% of the axial width of each axial side portion P1, P2. Here, the axial width of each first axial portion P11, P21 is equal to 30mm. In addition, the axial width of each second axial portion P12, P22 is equal to 3mm. Each axial portion P11, P21 only satisfies condition III because πx OD / N≤24mm. In addition, πx OD / N≥10mm. In this particular case, πx OD / N=17mm. In the above-mentioned variant form, N=98, πx OD / N≤24mm and πx OD / N≥10mm, more specifically, πxOD / N=22mm.

[0209] Note that in the first embodiment, in order to limit the transition area, each central rib 62, 64, 66 and the first axial side portion P1 and the second axial side portion P2 each include an axial portion P62, P64, P66, P11, P21, respectively, and these axial portions P62, P64, P66, P11, P21 only satisfy one of the conditions I, II, III and the axial width is greater than or equal to 70%, preferably 80%, and more preferably 90% of the axial width of each central rib 62, 64, 66 and the first axial side portion P1 and the second axial side portion P2.

[0210] The surface area void fraction of the tread 14 ranges from 27% to 45%, preferably from 30% to 40%, here equal to 36%. The volume void fraction of the tread 14 ranges from 17% to 35%, preferably from 20% to 30%, here equal to 24%.

[0211] The surface area porosity of each of the first axial side portion P1 and the second axial side portion P2 ranges from 20% to 30%, here equal to 25%. The volume porosity of each of the first axial side portion P1 and the second axial side portion P2 ranges from 5% to 10%, here equal to 8%.

[0212] The surface area porosity of the axially central portion P0 ranges from 35% to 45%, and is here equal to 41%. The volume porosity of the axially central portion P0 ranges from 25% to 35%, and is here equal to 30%.

[0213] The surface area porosity of each central rib 62, 64, 66 ranges from 5% to 10%, here equal to 7%. The volume porosity of each central rib 62, 64, 66 ranges from 0.5% to 5%, preferably from 0.5% to 2%, here equal to 1%.

[0214] The ratio of the surface area porosity of each central rib 62, 64, 66 to the surface area porosity of each of the first axial side portion P1 and the second axial side portion P2 is less than or equal to 0.35, preferably less than or equal to 3.0, more preferably in the range of 0.10 to 0.30, and here is equal to 0.28. The ratio of the volume porosity of each central rib 62, 64, 66 to the porosity of each of the first axial side portion P1 and the second axial side portion P2 is less than or equal to 0.20, preferably less than or equal to 0.15, more preferably in the range of 0.10 to 0.15, and here is equal to 0.13.

[0215] Now refer to Fig.10 A tire according to a second embodiment of the present invention will now be described. Similar elements to those of the first embodiment are denoted by the same reference numerals.

[0216] Unlike the first embodiment, the central rib 64 has no circumferential cutouts having a depth strictly less than 50% of the tread pattern height. In this case, the central rib does not comprise additional circumferential cutouts 74.

[0217] Furthermore, the central rib 64 comprises several axial portions, each of which satisfies only one of the conditions I, II, and III. In this particular case, the central rib 64 comprises, on the one hand, a first axial portion P641 having an axial width equal to 50% of the axial width Ln4 of the central rib 64 and satisfying only the condition III, and on the other hand, a second axial portion P642 having an axial width equal to 50% of the axial width Ln4 of the central rib 64 and satisfying only the condition I. Therefore, the axial width of the first axial portion P641 and the second axial portion P642 of the central rib 64, which respectively satisfy only one of the conditions I, II, and III, is greater than or equal to 70%, preferably 80%, more preferably 90%, and here equal to 100% of the axial width Ln4 of the central rib 64.

[0218] More specifically, the axial portion P641 comprises transverse cuts 91 having a depth Ht greater than or equal to 20% of the tread pattern height Hs and an axial length Lb greater than or equal to 20% of the axial width of the central rib 64, here equal to 50%. Over the entire circumference of the tire, the number of cuts 91 is N=125. All N transverse cuts 91 are arranged so that πx OD / N≤24 mm, thus satisfying only condition III. In a variant of this second embodiment, N=98 and likewise πx OD / N≤24 mm.

[0219] It will be noted that, unlike the first embodiment, the central rib 64 includes a transition area between the first axial portion P641 and the second axial portion P642 and between the first axial portion P641 and the second axial portion P642, and the axial width of the transition area is such that the central rib 64 does not include any axial portion that satisfies only one of the conditions I, II, III and has an axial width greater than or equal to 70% of the axial width of the central rib 64.

[0220] Now refer to Fig.11 A tire according to a third embodiment of the present invention will now be described. Similar elements to those of the previous embodiments are denoted by the same reference numerals.

[0221] Unlike the first embodiment, the central ribs 62 , 64 , 66 do not have any circumferential cutouts having a depth strictly less than 50% of the tread pattern height. In this case, each central rib 62 , 64 , 66 does not comprise a respective additional circumferential cutout 72 , 74 , 76 .

[0222] In addition, just as in the second embodiment, each central rib 62, 64, 66 includes several axial portions that satisfy only one of the conditions I, II, and III. In this particular case, each central rib 62, 64, 66 includes, on the one hand, a first axial portion P621, P641, P661, and on the other hand, a second axial portion P622, P642, P662, wherein the axial width of the first axial portion P621, P641, P661 is equal to 50% of each axial width Ln2, Ln4, Ln6 of each central rib 62, 64, 66 and satisfies only the condition III, and the axial width of the second axial portion P622, P642, P662 is equal to 50% of each axial width Ln2, Ln4, Ln6 of each central rib 62, 64, 66 and satisfies only the condition I. Therefore, the axial width of the first axial portion P621, P641 and P661 and the second axial portion P622, P642 and P662 of each central rib 62, 64, 66 which respectively only satisfies one of the conditions I, II, III is greater than or equal to 70%, preferably 80%, and more preferably 90% of the axial width of the central rib 64, which is equal to 100% of the axial width Ln2, Ln4, Ln6.

[0223] Now refer to Fig.12 A tire according to a fourth embodiment of the present invention will now be described. Similar elements to those of the previous embodiments are denoted by the same reference numerals.

[0224] Unlike the first embodiment, the central rib 64 has no circumferential cutouts having a depth strictly less than 50% of the tread pattern height. In this case, the central rib does not comprise additional circumferential cutouts 74.

[0225] Furthermore, the central rib 64 includes a plurality of axial portions P641 , P643 that respectively satisfy only one of the conditions I, II, and III, and a central portion P642 that does not satisfy any of the conditions I, II, and III.

[0226] In this particular case, on the one hand, the axial width of the axial portion P641 is equal to 50% of the axial width Ln4 of the central rib 64 and only satisfies condition III, and on the other hand, the axial width of the axial portion P643 is equal to 25% of the axial width Ln4 of the central rib 64 and only satisfies condition III, so that the entire axial width of the axial portions P641 and P643, which respectively only satisfy one of conditions I, II, and III (in this case condition III), is greater than or equal to 70% of the axial width of the central rib 64, which is equal to 75% of the axial width Ln4.

[0227] In addition, unlike the second and third embodiments, even if the central rib 64 includes several axial portions P641, P643 that respectively satisfy only one of the conditions I, II, and III, all the axial portions P641, P643 of the fourth embodiment satisfy only one of the conditions I, II, and III, in this case only condition III.

[0228] It will also be noted that, unlike the first embodiment, the central rib 64 includes two transition regions between different axial portions P641, P642 and P643 and the axial width of the transition regions is such that the central rib 64 does not include any axial portion that satisfies only one of the conditions I, II, III and whose axial width is greater than or equal to 70% of the axial width of the central rib 64.

[0229] More specifically, the axial portions P641, P643 comprise transverse cuts 91, 93, respectively, of depth Ht greater than or equal to 20% of the tread pattern height Hs and of axial lengths Lb, Lc greater than or equal to 20% of the axial width of the central rib 64, here equal to 50% and 25%, respectively. Over the entire circumference of the tire, the number of cuts 91, 93 is respectively N1=N3=125. All N1 transverse cuts 91 and all N3 transverse cuts 93 are arranged so that πx OD / N1≤24 mm and πx OD / N3≤24 mm, thus satisfying only condition III. A variant of this fourth embodiment would give N1=N3=98, so this would also give πxOD / N1≤24 mm and πx OD / N3≤24 mm, thus satisfying only condition III.

[0230] The axial portion P642 does not satisfy any of the conditions I, II, and III. Specifically, although Fig.12In the figure, over the entire circumference of the tire, the axial portion P642 includes N2 transverse cuts 95, the depth Ht of these N2=65 transverse cuts 95 is greater than or equal to 20% of the tread pattern height Hs and the axial length is greater than or equal to 20% of the axial width Ln4 of the central rib 64, here equal to 25%, but all N transverse cuts 95 are arranged so that 24mm<πx OD / N2<40mm.

[0231] Now refer to Fig.13 A tire according to a fifth embodiment of the present invention will now be described. Similar elements to those of the previous embodiments are denoted by the same reference numerals.

[0232] Different from the fourth embodiment, the central rib 64 includes several axial portions P641, P643, P644 respectively satisfying only one of the conditions I, II, III, and a central portion P642 satisfying none of the conditions I, II, III.

[0233] In this particular case, on the one hand, the axial width of the axial portion P641 is equal to 25% of the axial width Ln4 of the central rib 64 and only satisfies condition III, on the other hand, the axial width of the axial portion P643 is equal to 25% of the axial width Ln4 of the central rib 64 and only satisfies condition I, and finally, the axial width of the axial portion P644 is equal to 25% of the axial width Ln4 of the central rib 64 and only satisfies condition II, so that the axial widths of all the axial portions P641, P643 and P644, which respectively only satisfy one of conditions I, II, and III (in this case conditions I, II, and III), are greater than or equal to 70% of the axial width of the central rib 64, which is equal to 75% of the axial width Ln4.

[0234] More specifically, the axial portion P641 comprises transverse cuts 91 having a depth Ht greater than or equal to 20% of the tread pattern height Hs and an axial length Lc greater than or equal to 20% of the axial width of the central rib 64, here equal to 25%. Over the entire circumference of the tire, the number of cuts 91 is N1=125. All N1 transverse cuts 91 are arranged so that πx OD / N1≤24 mm, thus satisfying only condition III. A variant of this fifth embodiment would give N1=98, so that πx OD / N1≤24 mm, thus satisfying only condition III.

[0235] As in the fourth embodiment, the axial portion P642 does not satisfy any of the conditions I, II, and III.

[0236] The axial portion P644 comprises transverse cutouts 97 having a depth Ht greater than or equal to 20% of the tread pattern height Hs and an axial length Lc greater than or equal to 20%, here equal to 25%, of the axial width of the central rib 64. Over the entire circumference of the tire, the number of these cutouts 97 is N4=25. All N4 transverse cutouts 97 of the axial portion P644 are arranged so that πx OD / N4≥40 mm, preferably so that πx OD / N4≥60 mm, even more preferably so that πx OD / N4≥80 mm.

[0237] It will be noted that, unlike the first embodiment, the central rib 64 includes different axial portions P641, P642, P643 and P644 and three transition regions between the axial portions P641, P642, P643 and P644, the axial width of the transition regions being such that the central rib 64 does not include any axial portion that satisfies only one of the conditions I, II, III and whose axial width is greater than or equal to 70% of the axial width of the central rib 64.

[0238] Comparison test

[0239] The tire 10 according to the first embodiment of the present invention and the control tire W not conforming to the present invention were tested. Unlike the tire 10 according to the first embodiment, each axial portion P62, P64, P66 of the control tire W includes the following transverse incision: the depth of the transverse incision is greater than or equal to 20% of the tread pattern height Hs and the axial width is greater than or equal to 20% of the axial width Ln2, Ln4 and Ln6 of each central rib 62, 64, 66, so that each of these axial portions P62, P64, P66 satisfies condition III.

[0240] In these tests, a vehicle was equipped with four identical tyres 10 or tyres W inflated to 2.5 bar and subjected to a load equal to 470 daN, the noise generated by the tyres tested being measured according to UNECE Regulation 51-03.

[0241] The first test measures the external noise generated by the tested tire at a constant speed, that is, at zero acceleration. The second test measures the external noise generated by the tested tire during the acceleration phase (acceleration equal to 3m.s -2 The results are summarized in the following Table 1. In this table, the noise generated by the tire W at a constant speed is represented by R, and the noise generated during the acceleration phase is represented by R'.

[0242] Table 1

[0243]

[0244]

[0245] It will be noted that the tyre 10 according to the invention makes it possible to significantly reduce the external noise generated by the tyre, both at constant speed and during acceleration phases.

[0246] The present invention is not limited to the above-described embodiments.

[0247] In particular, without departing from the scope of the invention, it is conceivable that the axial central portion comprising the first, second and third main circumferential grooves and the first and second central ribs is arranged such that:

[0248] - the first central rib is axially located between the first main circumferential groove and the third main circumferential groove,

[0249] The second central rib is axially interposed between the second main circumferential groove and the third main circumferential groove.

Claims

1. A tire (10) for a passenger vehicle, the tire (10) having an outer diameter OD and comprising a tread (14), the tread (14) being intended to come into contact with the ground when the tire (10) is running via a tread surface (38), the tread surface (38) being axially delimited by a first axial edge and a second axial edge (41, 42) of the tread surface (38), the tread (14) comprising: - an axially central portion (P0), the axially central portion (P0) comprising main circumferential grooves (52, 54, 56, 58), the depth (Hr) of the main circumferential grooves (52, 54, 56, 58) being greater than or equal to 50% of the tread pattern height (Hs) and comprising at least a first main circumferential groove and a second main circumferential groove (52, 54) arranged axially on both sides of a midplane (M) of the tire (10), the first main circumferential groove and the second main circumferential groove (52, 54) being axially closest to the tread (14 ), the axial central portion (P0) extending axially from the axial outer edge (521) of the first main circumferential groove (52) to the axial outer edge (541) of the second main circumferential groove (54), the axial central portion (P0) comprising at least one central rib (62, 64, 66), the central rib or each central rib (62, 64, 66) being axially delimited by two main circumferential grooves (52, 54, 56, 58) having a depth (Hr) greater than or equal to 50% of the tread pattern height (Hs), - a first axial side portion and a second axial side portion (P1, P2), which are arranged axially outside the axial central portion (P0) and one on each side of the axial central portion (P0) axially relative to a midplane (M) of the tire (10), and are arranged such that: - said first axial side portion (P1) extends axially from a first axial edge (41) of the tread surface (38) to an axially outer edge (521) of a first main circumferential groove (52), - said second axial side portion (P2) extends axially from a second axial edge (42) of the tread surface (38) to an axially outer edge (541) of the second main circumferential groove (54), The central rib or each central rib (62, 64, 66) and the first and second axial side portions (P1, P2) each include at least one axial portion (P62, P64, P66, P11, P21, P641, P642, P643, P644, P622, P662) that satisfies only one of the following conditions I, II, III, and the axial width of all axial portions of the central rib or each central rib (62, 64, 66) and the first and second axial side portions (P1, P2) that respectively satisfies only one of the conditions I, II, III is greater than or equal to 70% of the axial width (Ln2, Ln4, Ln6, L1, L2) of the central rib or each central rib (62, 64, 66) and the first and second axial side portions (P1, P2): I - the axial portion (P62, P64, P66, P642, P643, P622, P662) does not include a transverse cutout (90, 90') having a depth (Ht) greater than or equal to 20% of the tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of the axial width (Ln2, Ln4, Ln6, L1, L2) of the central rib (62, 64, 66) or of the axial side portion (P1, P2), the axial portion being able to include at least one circumferential cutout (72, 74, 76, 82, 84) having a depth (Hc2, Hc4, Hc6, HI2, HI4) strictly less than 50% of the tread pattern height (Hs), II-The axial portion (P644) comprises transverse cuts (90, 90') having a depth (Ht) greater than or equal to 20% of the tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of the axial width of the central rib (62, 64, 66) or of the axial side portions (P1, P2), and all N transverse cuts (90, 90') having a depth (Ht) greater than or equal to 20% of the tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of the axial width (Ln2, Ln4, Ln6, L1, L2) of the central rib (62, 64, 66) or of the axial side portions (P1, P2) are arranged so that πx OD / N≥40 mm, the axial portion can include at least one circumferential cutout (72, 74, 76, 82, 84) having a depth (Hc2, Hc4, Hc6, HI2, HI4) strictly less than 50% of the tread pattern height (Hs), III-The axial portion (P11, P21, P621, P641, P661, P643) comprises a transverse cutout (90, 90) having a depth (Ht) greater than or equal to 20% of the tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of the axial width (Ln2, Ln4, Ln6, L1, L2) of the central rib (62, 64, 66) or of the axial side portion (P1, P2); 90'), all N transverse cuts (90, 90') having a depth (Ht) of a central rib (62, 64, 66) or of an axial portion greater than or equal to 20% of the tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of the axial width (Ln2, Ln4, Ln6, L1, L2) of the central rib (62, 64, 66) or of the axial side portion (P1, P2) are arranged so that πx OD / N≤24 mm, the axial portion can include at least one circumferential cut (72, 74, 76, 82, 84) having a depth (Hc2, Hc4, Hc6, HI2, HI4) strictly less than 50% of the tread pattern height (Hs), At least one axial portion of the central rib or one axial portion of a central rib (62, 64, 66) or one axial portion of the first axial side portion (P1) or one axial portion of the second axial side portion (P2) satisfies condition II, At least one axial portion of the central rib or one axial portion of a central rib (62, 64, 66) or one axial portion of the first axial side portion (P1) or one axial portion of the second axial side portion (P2) satisfies condition III.

2. The tire (10) according to claim 1, wherein: At least one axial portion of the or each central rib (62, 64, 66) satisfies condition II, while at least one axial portion of each of the first and second axial side portions (P0, P1) satisfies condition III.

3. The tire (10) according to claim 1 or 2, wherein: The depth of the central rib or each central rib (62, 64, 66) or the axial side portion or each axial side portion (P0, P1) is greater than or equal to 20% of the tread pattern height (Hs) and the axial length (La, Lb, Lc) is greater than or equal to 20% of the axial width (L1, L2, Ln1, Ln4, Ln6) of the central rib or each central rib (62, 64, 66) or the axial side portion or each axial side portion (P1, P2) and all N transverse cuts (90, 90') that meet condition III are arranged so that πx OD / N≥10mm.

4. The tire (10) according to claim 1 or 2, wherein: The axial width of all axial portions of the central rib or each central rib (62, 64, 66) and the first axial side portion and the second axial side portion (P1, P2), respectively, which only satisfies one of the conditions I, II, and III, is greater than or equal to 80% of the axial width (Ln2, Ln4, Ln6, L1, L2) of the central rib or each central rib (62, 64, 66) and the first axial side portion and the second axial side portion (P1, P2), respectively.

5. The tire (10) according to claim 1 or 2, wherein: The central rib or each central rib (62, 64, 66) or the first axial side portion (P1) or the second axial side portion (P2) includes several axial portions that respectively satisfy only one of the conditions II and III, and all axial portions of the central rib or each central rib (62, 64, 66) or the first axial side portion (P1) or the second axial side portion (P2) satisfy only one of the conditions II and III.

6. The tire (10) according to claim 1 or 2, wherein: The central rib or each central rib (62, 64, 66) and the first axial side portion and the second axial side portion (P1, P2) each include an axial portion, which satisfies only one of conditions II and III and has an axial width greater than or equal to 70% of the axial width of the central rib or each central rib (62, 64, 66) and the first axial side portion and the second axial side portion (P1, P2).

7. The tire (10) according to claim 1 or 2, wherein: A ratio of an axial width (L0) of the central portion (P0) to respective axial widths (L1, L2) of the first and second axial side portions (P1, P2) is greater than or equal to 3.

0.

8. The tire (10) according to claim 1 or 2, wherein: The first axial side portion and the second axial side portion (P1, P2) each include a transverse cutout (90, 90') extending axially from the axial outer end (E1) to the axial inner end (E2), and at least 50% of the transverse cutouts (90, 90') of each of the first axial side portion and the second axial side portion (P1, P2) are at least partially blocked by a connecting bridge (100), wherein the connecting bridge (100) connects the leading edge surface (Ft1) and the trailing edge surface (Ft2) and forms the axial inner end (E2) of the transverse cutout (90, 90').

9. The tire (10) according to claim 1 or 2, wherein: The surface area void fraction of each of the first axial side portion and the second axial side portion (P1, P2) ranges from 20% to 30%.

10. The tire (10) according to claim 1 or 2, wherein: The volume void ratio of each of the first axial side portion and the second axial side portion (P1, P2) ranges from 5% to 10%.

11. The tire (10) according to claim 1 or 2, wherein: The or each central rib (62, 64, 66) may have a surface area void fraction in the range of 5% to 10%.

12. The tire (10) according to claim 1 or 2, wherein: The or each central rib (62, 64, 66) has a volume void fraction in the range of 0.5% to 5%.

13. The tire (10) according to claim 1 or 2, wherein: The axial central portion (P0) comprises at least a third main circumferential groove (56) and at least a first central rib and a second central rib (62, 64, 66) and is arranged such that: - a first central rib (62) is axially located between the first main circumferential groove (52) and the third main circumferential groove (56), The second central rib (64) is axially interposed between the second main circumferential groove (54) and the third main circumferential groove (56).

14. The tire (10) according to claim 1 or 2, wherein: The axial central portion (P0) includes third and fourth main circumferential grooves (56, 58) and at least first, second and third central ribs (62, 64, 66), and is arranged such that: - a first central rib (62) is axially located between the first main circumferential groove (52) and the third main circumferential groove (56), - the second central rib (64) is axially located between the third main circumferential groove (56) and the fourth main circumferential groove (58), and The third central rib (66) is axially interposed between the fourth main circumferential groove (58) and the second main circumferential groove (54).

15. The tire (10) according to claim 1 or 2, wherein: The or at least one central rib (62, 64, 66) comprises at least one additional circumferential cutout (72, 74, 76), the or each additional circumferential cutout (72, 74, 76) comprising: - arranged axially between two circumferential grooves (52, 54, 56, 58), the or each central rib (62, 64, 66) being interposed between the two circumferential grooves (52, 54, 56, 58), and - The depth (Hc) is strictly less than 50% of the tread pattern height (Hs).

Images