Low-noise tires

Abstract

A tire (10) for a passenger vehicle has an axial central portion and axial lateral portions, the axial central portion and each axial lateral portion satisfying conditions I, II, and III: I - the part does not have transverse cutouts (90, 90'), II - the part comprises N transverse notches (90, 90') arranged such that π x OD / N ≥ 40 mm; III - the part comprises N transverse notches (90, 90') arranged such that π x OD / N≦24 mm; Condition I or II is satisfied by the axial central portion or by the axial lateral portion, and condition III is satisfied by the axial central portion or by the axial lateral portion.

Description

[Technical Field]

[0001] The present invention relates to a tire for passenger vehicles. Tire is understood to mean a casing intended to form, by cooperation with a support element, for example a rim, a cavity that can be pressurized to a pressure higher than atmospheric pressure. The tire according to the invention has a substantially toroidal structure exhibiting rotational symmetry around the main axis of the tire. [Background technology]

[0002] Tyres of size 245 / 45R 18 sold under the MICHELIN registered trademark and belonging to the PRIMACY 4 range are known from the prior art. Such tyres offer an excellent performance compromise, in particular between grip on wet or dry roads and the exterior noise generated by the tyre.

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

[0004] Tire manufacturers have therefore developed tires to reduce this exterior noise, for example by modifying the tire's tread pattern, as disclosed in WO 2018 / 199273, where grooves are provided with protrusions that shift the resonant frequency of the air column within the grooves away from the frequency range audible to the human ear. Nevertheless, providing grooves with these protrusions increases the complexity of manufacturing the corresponding molds and therefore the cost of the associated tires.

[0005] Another solution known today, disclosed in WO 2010 / 069510, consists in modifying the architecture of the tire by radially inserting a sublayer of material containing high-density fillers between the tire's tread layer and its crown reinforcement. This sublayer makes it possible to attenuate the sound power of the emitted noise, rather than shifting its frequency, as in WO 2018 / 199273. Nevertheless, providing a tire with such a sublayer not only increases the tire's cost, but also its mass and therefore its rolling resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 199273 [Patent Document 2] International Publication No. 2010 / 069510 Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to reduce exterior noise generated by a tire in a simple manner and at no additional cost compared to prior art tires. [Means for solving the problem]

[0008] To this end, the subject of the present invention is a tire for passenger vehicles comprising a tread having an outer diameter OD and intended to come into contact with the road surface when the tire is running through a tread surface axially delimited by first and second axial edges of the tread surface, the tread comprising: an axially central portion comprising at least first and second main circumferential grooves having a depth greater than or equal to 50% of the tread pattern height and axially arranged, one on each side of the median plane of the tire, the first and second main circumferential grooves being the axially furthest main circumferential grooves towards 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 or each central rib being axially separated by two main circumferential grooves having a depth greater than or equal to 50% of the tread pattern height; - one axially on each side of the axially central portion with respect to the median plane of the tire and arranged axially outward of the axially central portion; and the first axial lateral portion extends axially from the first axial edge of the tread surface distal to the axially outer edge of the first major circumferential groove; the second axial lateral portion extends axially from the second axial edge of the tread surface to a distal axial outer edge of the second major circumferential groove; the first and second axial transverse portions being arranged such that The central rib or each central rib and each first and second axial lateral portion meets one of the following conditions I, II, and III: Only one and at least one axial portion that satisfies conditions I, II, and III. Only one the total axial width of one or more axial portions of the or each central rib and each first and second axial transverse portion each satisfying the above condition is greater than or equal to 70% of the axial width of the or each central rib and each first and second axial transverse portion, I - does not comprise a transverse notch 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 lateral portion, and the axial portion comprises at least one circumferential notch having a depth strictly less than 50% of the tread pattern height; It may be prepared thing, II - the axial portion comprises 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 transverse portion, the total of N transverse cutouts 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 transverse portion being arranged so that π × OD / N ≥ 40 mm, and the axial portion comprises at least one circumferential cutout having a depth strictly less than 50% of the tread pattern height. It may be prepared thing, III - the axial portion comprises transverse notches 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 lateral portions, the total of N transverse notches of the central rib or of the axial portions 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 lateral portions being arranged so that π × OD / N≦24 mm, and the axial portion comprises at least one circumferential notch having a depth strictly less than 50% of the tread pattern height; It may be prepared thing, and Condition I or II is satisfied by at least one of the axial portions of the central rib or of one of the central ribs, or by one of the axial portions of the first axial transverse portion, or by one of the axial portions of the second axial transverse portion, Condition III is satisfied by at least one of the axial portions of the central rib or of one of the central ribs, or by one of the axial portions of the first axial transverse portion, or by one of the axial portions of the second axial transverse portion, the first and second axial transverse portions; Equipped with.

[0009] Due to one or more of the central ribs and axial lateral portions having either no or very few transverse notches or having a large number of transverse notches, the inventors behind the present invention have reduced the exterior noise generated by the tire.

[0010] In particular, the inventors behind the present invention have taken advantage of the fact that the exterior noise generated by a tire results from the excitation of the notches 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 overlap of the frequency spectrum of the noise resulting from the excitation of the notches with the frequency spectrum of the noise resulting from the mechanical structure, resonances at frequencies and harmonics of these frequency spectra are avoided so as to be able to significantly reduce the exterior noise emitted by the tire.

[0011] More specifically, the frequency spectrum for the noise arising from the mechanical structure is comprised between 600 Hz and 1100 Hz, this spectrum depending, inter alia, on the length of the tire's contact patch and the tire's dimensions and structure. According to the invention, the frequency spectrum for the noise arising from the excitation of the transverse notches of the or each central rib and of each first and second axial transverse portion is shifted relative to the frequency spectrum in the range of 600 Hz to 1100 Hz so as to reduce the exterior noise emitted by the tire. That is, for each axial portion of each central rib and of each first and second axial transverse portion, the number of notches in the tire's contact patch can be increased (i.e., the average spacing π×OD / N can be reduced) so as to shift the frequency spectrum of the noise arising from the excitation of the transverse notches towards higher frequencies. Conversely, for each axial portion of each central rib and of each first and second lateral axial portion, the number of notches in the tire contact patch can also be reduced (i.e., the average spacing π×OD / N can be increased) to shift the frequency spectrum of the noise resulting from the excitation of the transverse notches towards lower frequencies. This excitation also depends on the traveling speed of the vehicle, and therefore the values ​​of N in the spacing of the present invention can be selected according to the speed at which the vehicle is used.

[0012] According to the invention, condition I or II and condition III are satisfied at least once by at least one of the axial portions of the central rib or one of the central ribs and by at least one of the axial portions of the first and second lateral axial portions. Specifically, if condition I or II is satisfied only by the rib or all of the ribs and the first and second central axial portions, the tire is considered to have grip problems on wet roads. If condition III is satisfied only by the rib or all of the ribs and the first and second central axial portions, the stiffness of the tread is considered to be excessively reduced in the longitudinal direction due to an excessive number of transverse notches, which is considered to result in a decrease in grip on dry roads.

[0013] Within the context of the present invention, each axial section either satisfies a single condition from among conditions I, II, III, or none of conditions I, II, III. That is, axial progression along a central rib or a transverse axial section involves passing from a plane perpendicular to the axis of rotation in which one of conditions I, II, III is satisfied to a plane perpendicular to the axis of rotation in which none of conditions I, II, III is satisfied, i.e., from one axial section to another. Similarly, axial progression along a central rib or a transverse axial section involves passing from a plane perpendicular to the axis of rotation in which one of conditions I, II, III is satisfied to a plane perpendicular to the axis of rotation in which another of conditions I, II, III is satisfied, i.e., from one axial section to another. Finally, the progression along the axial direction of the central rib or axial transverse portion involves passing from a plane perpendicular to the axis of rotation in which one of conditions I, II, III is satisfied to a plane perpendicular to the axis of rotation in which the same conditions I, II, III are satisfied, i.e. remaining in one and the same axial portion.

[0014] The fact that the transverse cutouts to be taken into account when calculating the average spacing have both 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 associated central rib or axial lateral portion means that transverse cutouts that are not deep enough or axially long enough to contribute to the exterior noise emitted by the tire do not need to be taken into account.

[0015] Conditions I, II, and III Only oneThe fact that the total axial width of the or each central rib and one or more axial portions of each first and second lateral axial portion that satisfy condition I is greater than or equal to 70% of the axial width of the or each central rib and each first and second lateral axial portion means that embodiments can be considered in which at least an insignificant portion of the axial width of the or each central rib and each first and second lateral axial portion does not satisfy any of conditions I, II, and III, in this case corresponding to less than 30%. The fact that the axial width of the or each portion that does not satisfy any of conditions I, II, and III is relatively small ensures that the or each portion makes little or no contribution to the exterior noise emissions emitted by the tire.

[0016] Furthermore, the central rib or each central rib and each of the first and second axial lateral portions satisfy the conditions I, II, and III. Only one The fact that the rib has at least one axial portion satisfying the following conditions makes it possible to envisage embodiments in which different conditions I, II, III are satisfied or not satisfied by distinct axial portions of the or each central rib and of each first and second axial transverse portion. Only one The sum of the axial widths of the one or more axial portions satisfying is greater than or equal to 70% of the axial width of the or each central rib and of each first and second axial lateral portion.

[0017] If an axial portion of a rib or axial transverse portion does not satisfy the same conditions I, II, III as two adjacent axial portions of the same rib or the same axial transverse portion, or if an axial portion of a rib or axial transverse portion does not satisfy any of conditions I, II, III, but two adjacent axial portions of the same rib or the same axial transverse portion each satisfy one of conditions I, II, III, Only oneIf the above equation is satisfied, there will be two transition zones between the associated axial section and each adjacent axial section, and these two transition zones will emit exterior noise with a frequency spectrum that is likely to be superimposed on the tire's structural noise spectrum. Therefore, the number of transition zones will be minimized, if not eliminated. Furthermore, this will firstly minimize the number of conditions I, II, III that are satisfied on one and the same central rib or one and the same axial lateral section, and secondly, minimize the number of conditions I, II, III that are satisfied on one and the same rib or one and the same axial lateral section. Only one is satisfied, axial portions that do not satisfy any of conditions I, II, and III and that could conceivably be sandwiched axially between various axial portions that do satisfy a single condition I, II, and III will be minimized, if not eliminated.

[0018] OD is the outer diameter of the tire measured on the median plane of the tire. Thus, π x OD is the circumference of the tire measured on the median plane of the tire. N and OD or π x OD are measured on an unloaded tire and can be measured either inflated or uninflated; what is important for N and OD or π x OD is that they are measured under the same conditions.

[0019] The axial width of the axial portions of the axial central or lateral portions of the central rib is the axial distance between two planes perpendicular to the rotational axis of the tire that pass through the inner and outer axial edges of the axial central or lateral portions of the central rib.

[0020] The axial length of a transverse notch is the axial distance between two planes perpendicular to the axis of rotation of the tire that pass through the inner and outer axial ends of the transverse notch, respectively.

[0021] According to the invention, at least a portion of the central rib or of one of the central ribs, at least a portion of the first axial lateral portion or at least a portion of the second axial lateral portion comprises a transverse notch, meaning either a groove or a sipe, forming a spatial opening on the tread surface.

[0022] A sipe or groove has two main characteristic dimensions on the tread surface, a width and a curvilinear length, which are such that the curvilinear length is at least equal to twice the width. A sipe or groove is thus bounded by at least two major side surfaces that determine its curvilinear length, connected by a base surface, and separated from each other by a non-zero distance called the width of the notch.

[0023] In a new tire, the width of a cutout is the maximum distance between the two major sides, measured at the radial dimension coinciding with the tread surface when the cutout is not chamfered, or between the outermost radial dimension of the cutout and the innermost radial dimension of the chamfer when the cutout is chamfered. In cases where a cutout has two distinct portions with different widths W1 and W2, such that 0.67≦W1 / W2≦1.50, the width of the cutout is the width of the portion with the greatest curvature. The distinct portions are separated from each other by an interruption in the curvature of each side of each portion, such as a localized or abrupt step or a localized or abrupt narrowing.

[0024] On a new tire, the depth of a cutout is the maximum radial distance between the bottom of the cutout and its projection onto the road surface when the tire is running. The maximum value for the cutout depth is called the tread pattern height.

[0025] The sipes are such that the distance between the major sides is suitable to allow at least partial contact between the major sides that define the sipes as they pass through the contact patch when the tire is new and under normal running conditions, including, inter alia, when the tire is under nominal load and pressure.

[0026] The grooves are such that the distance between the major sides is such that the major sides cannot come into contact with each other under normal running conditions, including, inter alia, when the tire is under nominal load and pressure.

[0027] The notches may be transverse or circumferential.

[0028] The transverse cutouts extend in an average direction that forms an angle with the circumferential direction of the tire that is greater than 30°, and preferably greater than or equal to 45°. The average direction is the shortest curve parallel to the tread surface that connects the two ends of the cutout. The transverse cutouts may be continuous, such that the two major sides that determine their length are uninterrupted along the length of the transverse cutout, i.e., not interrupted by a tread block or another cutout. Equivalently, the transverse cutouts may be discontinuous, such that the two major sides that determine their length are interrupted by one or more tread blocks and / or one or more cutouts, i.e., interrupted by one or more tread blocks and / or one or more other cutouts.

[0029] The circumferential cutout extends in an average direction that forms an angle with the circumferential direction of the tire that is less than or equal to 30°, preferably less than or equal to 10°. The average direction is the shortest curve parallel to the tread surface that connects the two ends of the cutout. In the case of a continuous circumferential cutout, the two ends coincide with each other and are joined by a curve that forms the entire circumference of the tire. The circumferential cutout can be continuous, meaning that the two major sides that determine its length are uninterrupted around the entire circumference of the tire, i.e., not interrupted by a tread block or another cutout. Equivalently, the circumferential cutout can be discontinuous, meaning that the two major sides that determine its length are interrupted around the entire circumference of the tire by one or more tread blocks and / or one or more cutouts, i.e., interrupted by one or more tread blocks and / or one or more other cutouts.

[0030] The main direction of the cutout is the direction in which a curve extends equidistant from each of the edges of the cutout in the radial dimension of the tread surface, and the curve length is the length between each of the ends of the cutout measured along this curve equidistant from each of the edges of the cutout in the radial dimension of the tread surface.

[0031] In the case of a circumferential cutout located outboard of the median plane of the tire, the sides are referred to as the axially inner and axially outer surfaces, with the axially inner surface being located axially inboard of the axially outer surface with respect to the median plane at a given azimuthal location.

[0032] In the case of a transverse cutout, the sides are referred to as the leading and trailing faces, the leading face being the face whose edge enters the ground contact patch before the edge of the trailing face for a given circumferential line.

[0033] Circumferential grooves having a depth greater than or equal to 50% of the tread pattern height and containing the first and second axial lateral portions and one or more central ribs therebetween are referred to as major ribs. Thus, in cases where the tread pattern height is at least twice the height of the legal tread wear indicator and is representative of the majority of passenger tires, these major circumferential grooves have a depth that lasts for more than half of the tire's wearable tread height. Thus, such major circumferential grooves greater than or equal to 50% of the tread pattern height will not disappear until the tire has worn down 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 legal tread wear indicator when the tire is new and the projection of the legal tread wear indicator on the road surface when the tire is in operation. Such legal tread wear indicators are mandated by, for example, United Nations regulations R30 and R54, US standard FMVSS139, or Chinese standard GB97743, and are intended to inform tire users of the legal tire tread wear threshold beyond which it is dangerous to drive, especially on wet roads.

[0034] Traditionally, the tread surface is determined on a tire mounted on a nominal rim and inflated to a nominal pressure within the meaning of the 2019 standards of the European Tyre and Rim Technical Organization (ETRTO). The axial width of the tread surface is simply measured when there is a clear boundary between the tread surface and the rest of the tire. If the tread surface is continuous with the outer surface of the tire's sidewall, the axial boundary of the tread surface passes through the point where the angle between the tangent of the tread surface and a line passing through a point parallel to the axial direction is equal to 30°. When there are several points in a meridian section where this angle is equal to 30° in absolute value, the radially outermost point is taken.

[0035] The tire according to the invention has a substantially toroidal shape about a pivot axis substantially coinciding with the axis of rotation of the tire, this pivot axis defining three directions conventionally used by those skilled in the art: axial, circumferential and radial.

[0036] The expression "axial" means a direction substantially parallel to the tire's pivot axis, i.e., the tire's axis of rotation.

[0037] The expression "circumferential" means a direction substantially perpendicular to both the axial direction and the radius of the tire (in other words, a tangent to a circle centered on the tire's axis of rotation).

[0038] The expression "radial" means any direction along the radius of the tire, i.e., any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[0039] The expression "median plane of the tire" (denoted M) means the plane perpendicular to the tire's axis of rotation, axially midway between the two beads and passing through the axial center of the crown reinforcement.

[0040] The expression "equatorial circumferential plane of the tire" (denoted E) means the plane that passes through the tire's equator in the meridian section and is perpendicular to the median plane and the radial direction. The tire's equator is the axis that, in the meridian section (perpendicular to the circumferential direction and parallel to the radial and axial directions), is parallel to the tire's axis of rotation and is equidistant between the radially outermost point of the tread intended to come into contact with the road surface and the radially innermost point of the tire intended to come into contact with the support, for example the rim, the distance between these two points being equal to H.

[0041] The expression "meridian plane" means a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0042] "Radially inner" and "radially outer" mean "nearer than" and "farther from" the tire's axis of rotation, respectively. "Axially inner" and "axially outer" mean "nearer than" and "farther from" the tire's median plane, respectively.

[0043] The term "bead" means the part of a tire intended to enable the tire to be mounted on a mounting support, for example a wheel provided with a rim. Each bead is therefore intended, inter alia, to come into contact with the flange of the rim and to enable it to be mounted.

[0044] Any range of values ​​expressed by the phrase "between a and b" denotes a range of values ​​that runs from greater than a to less than b (i.e., excluding the endpoints a and b), whereas any range of values ​​expressed by the phrase "from a to b" means a range of values ​​that runs from a to b (i.e., including the exact endpoints a and b).

[0045] The tire of the invention is intended for passenger cars defined in accordance with the 2019 standards of the European Tyre and Rim Technical Organisation or "ETRTO", having a cross-section in meridian section characterized by a section height H and a nominal section width S such that the ratio H / S, expressed as a percentage within the meaning of the 2019 standards of the European Tyre and Rim Technical Organisation or "ETRTO", is at most equal to 90, preferably at most equal to 80, more preferably at most equal to 70 and at least equal to 30, preferably at least equal to 40, and the nominal section width S is at least equal to 115 mm, preferably at least equal to 155 mm, more preferably at least equal to 175 mm and at most equal to 385 mm, preferably at most equal to 315 mm, more preferably at most equal to 285 mm, even more preferably at most equal to 255 mm. In addition, the diameter D at the flange, which defines the diameter of the tire-mounted rim, is at least equal to 12 inches, at least equal to 16 inches, and at most equal to 24 inches, preferably at most equal to 20 inches.

[0046] Advantageously, in order to consider only the transverse notches that contribute the most due to their depth to the exterior noise emitted by the tire, the total of N transverse notches to be taken into account for calculating the average spacing have a depth greater than or equal to 30% of the tread pattern height, preferably greater than or equal to 40%.

[0047] Similarly, in order to consider only the transverse notches that contribute most due to their width to the exterior noise emitted by the tire, the total of the N transverse notches to be taken into account for calculating the average spacing has an axial length greater than or equal to 30%, preferably greater than or equal to 50%, and more preferably greater than or equal to 75% of the axial width of the central rib or of the axial lateral portions.

[0048] Naturally, in order to take into account the transverse cutouts that contribute the greatest due to both their width and axial length to the exterior noise emitted by the tire, in a highly preferred embodiment, consideration of transverse cutouts having a depth greater than or equal to 40% of the tread pattern height and an axial length greater than or equal to 75% of the axial width of the central rib or of the axial lateral portions will favor the calculation of the average spacing.

[0049] In one preferred embodiment, at least one of the axial portions of the or each central rib satisfies condition I or II and at least one of the axial portions of each of the first and second axial transverse portions satisfies condition III, preferably at least one of the axial portions of the or each central rib satisfies condition I and at least one of the axial portions of each of the first and second axial transverse portions satisfies condition III.

[0050] During the acceleration phase, the vehicle is less heavily loaded at the front, and therefore the central axial portion is in contact with the road surface on which it is traveling, and the first and second lateral axial portions are in only relatively light contact with the road surface, if at all. Therefore, in order to reduce as much as possible the noise emitted during this acceleration phase, especially in the case of vehicles using front-wheel drive, it is preferable to make the central axial portion as quiet as possible, and therefore to have one or more central ribs with only a few or even no transverse cutouts.

[0051] Advantageously, and in order to avoid as far as possible any potential overlap of the frequency spectrum of the noise resulting from the excitation of the notches with the frequency spectrum of the noise resulting from the mechanical structure, the total of N transverse notches of the central rib or each central rib or axial lateral portion or each axial lateral 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 each central rib or axial lateral portion or each axial lateral portion satisfying condition II are preferably arranged so that π×OD / N≧60 mm, and even more preferably π×OD / N≧80 mm.

[0052] In one preferred embodiment, the total of N transverse notches in the central rib or each central rib or axial lateral portion or each axial lateral 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 each central rib or axial lateral portion or each axial lateral portion that satisfy condition III are arranged so that π×OD / N≧10 mm, preferably π×OD / N≧15 mm.

[0053] By limiting the number of transverse notches in the tire's contact patch, an excessive reduction in the area of ​​the tread in contact with the road surface is avoided, and therefore an excessive increase in the pressure exerted by the road surface on each of the edge corners forming the edges of the transverse notches is avoided, which in turn avoids compromising grip on dry roads, which is an inverse function of the pressure exerted by the road surface on the tread.

[0054] Advantageously, and in order to avoid as far as possible any potential overlap of the frequency spectrum of the noise resulting from the excitation of the notches with the frequency spectrum of the noise resulting from the mechanical structure, the total of N transverse notches of the central rib or each central rib or axial lateral portion or each axial lateral 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 each central rib or axial lateral portion or each axial lateral portion satisfying condition III are preferably arranged so that π×OD / N≦22 mm, and even more preferably π×OD / N≦20 mm.

[0055] Very advantageously, in order to limit as much as possible the exterior noise generated by one or more parts that do not satisfy any of conditions I, II, and III, Only one The overall axial width of one or more axial portions of the or each central rib and each first and second axial transverse portion satisfying the above is greater than or equal to 80%, preferably 90%, of the axial width of the or each central rib and each first and second axial transverse portion.

[0056] As described above, the central rib or each central rib or first axial transverse portion or second axial transverse portion may each satisfy one of conditions I, II, III so as to minimize the variety of the transition zone by reducing the number of conditions satisfied on one and the same central rib or one and the same axial transverse portion. Only one In the case where the central rib or each central rib or the first axial transverse portion or the second axial transverse portion has several axial portions that satisfy the above conditions, the entire axial portion of the central rib or each central rib or the first axial transverse portion or the second axial transverse portion does not satisfy any of the conditions I, II, and III. Only one Satisfy.

[0057] As described above, the or each central rib and each first and second axial transverse portion is configured to satisfy one of conditions I, II, and III so as to minimize the number of axial portions that do not satisfy any of conditions I, II, and III sandwiched between various axial portions that satisfy a single condition I, II, and III in the axial direction, thereby minimizing the number of transition zones. Only one and has an axial portion having an axial width greater than or equal to 70%, preferably 80%, more preferably 90% of the axial width of the or each central rib and of each first and second axial transverse portion.

[0058] In one advantageous embodiment, the ratio of the axial width of the central portion to the axial width of each of the first and second lateral axial portions is greater than or equal to 3.0, preferably in the range of 3.0 to 5.0, more preferably 4.0 to 4.5.

[0059] In this embodiment, the axially central portion has the greatest axial width compared to the first and second lateral axial portions. This embodiment is particularly advantageous in that the smaller the axial width of the axially central portion, the greater the extent to which the noise generated by the transverse cutouts can be reduced when the or each rib satisfies condition I or II.

[0060] Advantageously, the axially central portion has an axial width greater than or equal to 50% of the axial width of the tread surface of the tire when new, preferably greater than or equal to 60%. Advantageously, the axially central portion has an axial width less than or equal to 80% of the axial width of the tread surface of the tire when new, preferably less than or equal to 70%.

[0061] Advantageously, each of the first and second lateral axial portions has an axial width that is less than or equal to 25% of the axial width of the tread surface of the tire when new, preferably less than or equal to 20%. Advantageously, each of the first and second lateral axial portions has an axial width that is greater than or equal to 5% of the axial width of the tread surface of the tire when new, preferably greater than or equal to 10%.

[0062] The advantageous features of each main circumferential groove: each main circumferential groove has a depth ranging from 4.0 mm to the tread pattern height, preferably from 5.0 mm to the tread pattern height, and even more preferably from 5.5 mm to the tread pattern height; Each main circumferential groove has a width 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 even more preferably in the range of 8.0 mm to 15.0 mm.

[0063] Advantageously, when each of the first and second axial transverse portions comprises a transverse cutout extending axially from its axially outer end to its axially inner end, at least 50%, preferably 75%, and even more preferably, of each of the transverse cutouts of each of the first and second axial transverse portions are at least partially blocked by a connecting bridge connecting the front and rear faces and forming the axially inner end of the transverse cutout.In order to take into account only the transverse cutouts that contribute most to noise, preferably, the above-mentioned characteristics apply to the entire set of N 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 each of the first and second axial transverse portions.

[0064] In other words, the connecting bridge forms part of the axial outer surface of the first or second main circumferential groove. Furthermore, the presence of the connecting bridge limits or even completely eliminates air communication between the transverse cutout and the axially central main circumferential groove, and therefore also limits or even completely eliminates acoustic resonance of a potential air column that would be established between the transverse cutout and the circumferential groove.

[0065] Even more advantageously, the connecting bridge is arranged to completely block communication between the transverse cutout and the first or second main circumferential groove when the transverse cutout penetrates into the contact patch when the tire is in contact with the road surface during movement. Furthermore, this eliminates any risk of acoustic resonance of the air column between the transverse cutout and the circumferential groove.

[0066] The advantageous features of each transverse cutout: each transverse cutout has a depth 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, and even more preferably in the range of 5.0 mm to the tread pattern height; Each transverse notch has a width less than or equal to 2.0 mm, preferably in the range of 0.5 mm to 2.0 mm.

[0067] Advantageously, at least one of the transverse cutouts of at least one of the first and second axial transverse portions, preferably at least 25%, more preferably at least 40%, of the transverse cutouts of at least one of the first and second axial transverse portions are the main portion extends over a main curve length that is strictly greater than 50% of the total curve length of the transverse cutout, the complementary portion extends over a complementary curved length that is strictly less than 50% of the total curved length of the transverse cutout, is arranged axially outside the main portion, and has a width that is greater than the width of the main portion; Thus, it has a main portion and a complementary portion separated from each other by an interruption in the curvature of each side.

[0068] Such a supplemental portion allows for effective drainage and therefore better grip performance on wet roads.

[0069] A preferred feature of the tire is that the surface area voids of the tread are in the range of 27% to 45%, preferably in the range of 30% to 40%.

[0070] A preferred feature of the tire is that the volume voids of the tread are in the range of 17% to 35%, preferably in the range of 20% to 30%.

[0071] Such surface and volume porosity ensures effective drainage under driving conditions on wet roads.

[0072] Preferably, the surface area porosity of each of the first and second axial transverse portions is in the range of 20% to 30%.

[0073] Also preferably, the volume porosity of each of the first and second axial transverse portions is in the range of 5% to 10%.

[0074] Preferably, the surface area porosity of the axially central portion is in the range of 35% to 45%.

[0075] Also preferably, the volume porosity of the central portion in the axial direction is in the range of 25% to 35%.

[0076] Preferably, the surface area porosity of the or each central rib is in the range of 5% to 10%.

[0077] Also preferably, the or each central rib has a volume porosity in the range of 0.5% to 5%, preferably in the range of 0.5% to 2%.

[0078] Advantageously, the ratio of the surface area porosity of the or each central rib to the surface area porosity of each of the first and second axial lateral portions is less than or equal to 0.35, preferably less than or equal to 0.30, and more preferably in the range of 0.10 to 0.30.

[0079] Also advantageously, the ratio of the volume porosity of the or each central rib to the volume porosity of each of the first and second axial transverse portions is less than or equal to 0.20, preferably less than or equal to 0.15, and more preferably in the range of 0.10 to 0.15.

[0080] The surface area porosity of the tread, of a portion of the tread, or of the rib is the difference between the total contact area AT of the tread, of parts of the tread or of the ribs of a new tire, inflated to a nominal pressure and under a nominal load, which is in contact with a smooth road surface, for example a pane of glass, and the contact area AC of the elements of the tread, of parts of the tread or of the ribs that are in contact with the road surface during travel, the total area AT of the contact patch of a portion of the tread or of a rib of a tire tread that is new, inflated to its nominal pressure and under nominal load, thereby in contact with a smooth road surface; is the ratio that relates

[0081] The volume void ratio of a tread, tread portion, or rib is the ratio of the total volume of the cutouts in the tread, tread portion, or rib of a new tire to the total volume of the tread, tread portion, or rib of an otherwise identical new tire without any cutouts. The tread is bounded axially by two planes perpendicular to the tire's axis of rotation and passing through the axial edges of the tread surface. A tread portion or rib is bounded radially by two planes perpendicular to the tire's axis of rotation and passing through the axial edges of said portion or rib. A tread, tread portion, or rib is bounded radially by the tread surface and a curved surface parallel to the new tire's tread surface and passing through the radially innermost point of the deepest cutout in the new tire's tread.

[0082] For determining the surface area porosity, the nominal load is equal to 80% of the rated load indicated by the European Tyre and Rim Technical Organisation or "ETRTO" 2019, and the nominal pressure is equal to 2.5 bar.

[0083] In one advantageous embodiment, the axially central portion includes at least a third main circumferential groove and at least first and second central ribs. a first central rib is included axially between the first and third major circumferential grooves; a second central rib is included axially between the second and third major circumferential grooves; The equipment shall be arranged as shown below.

[0084] Therefore, increasing the number of central ribs for a given axial width of the axial center portion improves water drainage across the entire axial width of the tread.

[0085] In a further preferred embodiment, the axially central portion includes third and fourth main circumferential grooves and at least first, second, and third central ribs. a first central rib is included axially between the first and third major circumferential grooves; a second central rib is included axially between the third and fourth major circumferential grooves; a third central rib is included axially between the fourth major circumferential groove and the second major circumferential groove; The equipment shall be arranged as shown in the figure.

[0086] The presence of three central ribs further improves drainage.

[0087] In this further preferred embodiment, the first central rib extends axially from the axially inner edge of the first major circumferential groove to the axially outer edge of the third major circumferential groove; the second central rib extends axially from the axially outer edge of the third major circumferential groove to the axially inner edge of the fourth major circumferential groove; the third central rib extends axially from the axially outer edge of the fourth major circumferential groove to the axially inner edge of the second major circumferential groove;

[0088] In the embodiments shown thus far, the or each central rib has an axial width that is less than or equal to 30% of the axial width of the axial center portion, preferably less than or equal to 25%. Thus, regardless of the number of central ribs, water drainage by each of the central ribs is facilitated by reducing the axial width of each of these central ribs.

[0089] The or each central rib has a sufficient axial width greater than or equal to 10% of the axial width of the axial center portion, preferably greater than or equal to 15%, in order to have a sufficient tread surface to reduce the local pressure that the road surface applies to the tire, thereby ensuring good grip on dry roads.

[0090] In one highly preferred embodiment, the or each central rib has an axial width in the range from 20mm to 40mm, preferably from 25mm to 35mm.

[0091] In an embodiment that improves grip on wet roads while at the same time generating little or no additional noise in the axially central portion and not impairing the tire behavior, the central rib or at least one of them, preferably each central rib, comprises: - axially arranged between two circumferential grooves with a central rib or ribs therebetween, -having a depth strictly less than 50% of the tread pattern height, preferably less than or equal to 30% of the tread pattern height, more preferably in the range of 10% to 30% of the tread pattern height; At least one additional circumferential notch is provided.

[0092] In particular, the or each additional circumferential cutout contributes little or nothing to the generation of noise resulting from excitation of the cutouts, particularly since due to its circumferential orientation and therefore the circumferential orientation of its side edge there are no edge corners of the or each additional circumferential cutout that come into contact with the road surface when the tire is running.

[0093] The or each additional circumferential notch can store water when driving on a wet road due to the void volume it creates, thereby improving grip on wet roads. Furthermore, each additional circumferential notch divides the central rib, which is formed into two axial sections separated by the main circumferential notch on the one hand and the additional circumferential notch on the other hand. This means that each of the axial sections of the central rib has a shorter axial width than if the central rib did not have the additional circumferential notch, and therefore has a higher ability to remove water from the center of each axial section towards the main circumferential notch and each of the additional circumferential notches.

[0094] Finally, the or each additional circumferential notch does not deteriorate the behavior of the tire, especially with regard to lateral stiffness, due to its relatively small depth.

[0095] Due to its advantageous features, the axial width of the or each additional circumferential notch 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 notch is in the range of 1.0 mm to 4.0 mm; the depth of the or each additional circumferential notch is less than or equal to 3.0 mm, preferably in the range of 1.0 mm to 3.0 mm;

[0096] By preferring additional circumferential notches whose width is greater than their depth, the axial width of each of the axial portions of the central rib located on either side of the additional circumferential notch is reduced, thus enhancing the ability of the tire to remove water to each of the main circumferential notches, an effect that is more significant the greater the axial width of the or each additional circumferential notch. Nevertheless, this axial width must not be excessively large in order to have a sufficient tread area to reduce the local pressure that the road surface exerts on the tire, thereby ensuring good grip on dry roads.

[0097] In an embodiment that improves grip on wet roads while at the same time generating little or no extra noise in the first axial lateral portion and not impairing the behavior of the tire, the first axial lateral portion, like the axial central portion, - axially disposed between the first circumferential groove and the first axial end of the tread surface; -having a depth strictly less than 50% of the tread pattern height, preferably less than or equal to 30% of the tread pattern height, more preferably in the range of 10% to 30% of the tread pattern height; At least one additional circumferential notch is provided.

[0098] Likewise, in order to improve grip on wet roads and at the same time generate little or no extra noise in the second axial lateral portion and not deteriorate the behavior of the tire, the second axial lateral portion, like the axial central portion and the first axial lateral portion, axially disposed between the second circumferential groove and the second axial end of the tread surface; -having a depth strictly less than 50% of the tread pattern height, preferably less than or equal to 30% of the tread pattern height, more preferably in the range of 10% to 30% of the tread pattern height; At least one additional circumferential notch is provided.

[0099] Just like the additional circumferential notch in the axially central portion, this advantageous feature improves the tire's ability to remove water and at the same time ensures good grip on dry roads. the axial width of the or each additional circumferential notch of the first axial transverse portion is in the range from 3% to 15%, preferably from 3% to 10%, of the axial width of the first axial transverse portion; the axial width of the or each additional circumferential notch of the second axial transverse portion is in the range of 3% to 15%, preferably 3% to 10%, of the axial width of the second axial transverse portion.

[0100] In one highly preferred embodiment, the axial width of the or each additional circumferential notch, regardless of whether the or each additional circumferential notch is made in the first axial transverse portion or in the second axial transverse portion, is in the range of 1.0 mm to 4.0 mm; the depth of the or each additional circumferential notch, regardless of whether the or each additional circumferential notch is made in the first axial transverse portion and / or in the second axial transverse portion, is less than or equal to 3.0 mm, preferably in the range of 1.0 mm to 3.0 mm.

[0101] In an embodiment that allows reducing the pressure experienced by the edge corners that form the edges of the cutouts and thus improving grip on dry roads, at least one of the main circumferential grooves is chamfered. In other words, if the boundary of each main circumferential groove between which the or one of the central ribs is contained is axially defined by axially inner and axially outer surfaces that bound the main circumferential groove axially inward and outward and are connected to each other by a bottom surface that bounds the main circumferential groove radially inward, at least one of the circumferential grooves, preferably each main circumferential groove, is arranged such that at least one of the axially inner and axially outer surfaces is connected to at least one of the axially inner and axially outer edges of the main circumferential groove by a chamfer, preferably each of the axially inner and axially outer surfaces is connected to each of the axially inner and axially outer edges of each main circumferential groove, respectively, by a chamfer.

[0102] The chamfer on the circumferential cutout can be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a plane that is inclined relative to the inner and outer axial surfaces and continues to the inner or outer axial edge that bounds the circumferential cutout in the axial direction. A rounded chamfer is formed by a curved surface that continues to the inner or outer axial surface and meets these surfaces tangent to them. The chamfer on the circumferential cutout is characterized by a height and width that are equal to the radial and axial distances, respectively, between the common point of the inner or outer axial surface extended by the chamfer and the inner or outer axial edge that bounds the circumferential cutout in the axial direction.

[0103] With a view to further improving grip on dry roads, if conditions II and / or III are met, at least 50%, preferably at least 75%, and even more preferably each transverse cutout is chamfered, in other words if each transverse cutout is bounded radially by a front face and a rear face that bound it circumferentially and are connected to one another by a base face that bounds it radially inward, at least 50%, preferably at least 75%, and even more preferably each transverse cutout is arranged so that at least one of the front and rear faces is connected to at least one of the leading and trailing edges of the transverse cutout by a chamfer, preferably each front and rear face being connected to each of the leading and trailing edges of each transverse cutout, respectively, by a chamfer.

[0104] 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 or trailing face and continues circumferentially to the leading or trailing edge that bounds the transverse cutout. A rounded chamfer is formed by a curved surface that continues to the leading or trailing face and meets the tangent to these faces. A chamfer on a transverse cutout is characterized by a height and width that are equal to the radial distance and the distance perpendicular to the leading or trailing face, respectively, between the common point with the leading or trailing face extended by the chamfer and the leading or trailing edge that bounds the transverse cutout circumferentially.

[0105] In a conventional manner, the tire comprises a crown, two sidewalls, and two beads, each sidewall connecting a respective bead to the crown. The crown also conventionally comprises a tread and a crown reinforcement disposed radially inwardly thereof. The tire further comprises a carcass reinforcement secured within each bead and extending radially inwardly of the crown within each sidewall.

[0106] Conventionally, the crown reinforcement comprises at least one crown layer containing reinforcing elements, which are preferably woven or metallic filamentary elements.

[0107] In an embodiment making it possible to achieve the performance characteristics of a tire known as a radial tire as defined by the 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 along a main direction forming an angle with the circumferential direction of the tire ranging from 80° to 90° in absolute value.

[0108] The invention will be better understood on reading the following description, given purely as a non-limiting example with reference to the drawings in which: [Brief explanation of the drawings]

[0109] [Figure 1] 1 is a meridian section of a tire according to a first embodiment of the invention, taken parallel to its axis of rotation; [Figure 2] 2 is a cutaway view of the tire of FIG. 1 showing the placement of filamentary reinforcing elements in and under the crown. [Figure 3] FIG. 2 is a perspective view of the tread of the tire of FIG. 1. [Figure 4] 4 is a meridian section of the tread of FIG. 3 taken parallel to the axis of rotation of the tire; [Figure 5] FIG. 5 is a detailed view of region V in FIG. 4. [Figure 6] FIG. 4 is a detailed view of region VI in FIG. 3. [Figure 7] FIG. 7 is a detailed view of region VII in FIG. 6. [Figure 8] FIG. 7 is a detailed view of region VIII in FIG. 6. [Figure 9] FIG. 2 is a schematic view of the tire of FIG. 1. [Figure 10] 10 is a view similar to FIG. 9 of a tire according to a second embodiment of the invention; [Figure 11] 10 is a view similar to FIG. 9 of a tire according to a third embodiment of the invention; [Figure 12] 10 is a view similar to FIG. 9 of a tire according to a fourth embodiment of the invention; [Figure 13] 10 is a view similar to FIG. 9 of a tire according to a fifth embodiment of the invention; DETAILED DESCRIPTION OF THE INVENTION

[0110] The coordinate system X, Y, Z corresponding to the axial (Y), radial (Z) and circumferential (X) directions of the tire is shown in the tire diagram.

[0111] In the following description, measurements taken are taken with the tire in an unloaded, uninflated state, except for volume void fraction and surface area void fraction measurements.

[0112] Figure 1 illustrates a tire, designated by the general reference number 10, according to the invention. The tire 10 has a substantially donut shape about a pivot axis substantially parallel to an axial direction Y. The tire 10 has a size of 245 / 45R18 for passenger cars. In the various figures, the tire 10 is depicted as new, i.e. when not yet run. The outer diameter OD of the tire 10 is equal to 678 mm.

[0113] The tire 10 comprises a crown 12, which comprises a tread 14 intended to be in contact with the road surface when in motion, and a crown reinforcement 16 extending in the circumferential direction X within the crown 12. Furthermore, the tire 10 comprises a mounting support therefor, for example an airtight layer 18, airtight to inflation gases, intended to delimit, together with this mounting support, a closed internal cavity when mounted on a rim.

[0114] The crown reinforcement 16 comprises an actuation reinforcement 20 and a hoop reinforcement 22. The actuation reinforcement 16 comprises at least one actuation layer, here two actuation layers 24, 26. In this particular case, the actuation reinforcement 16 is made up of two actuation layers 24, 26. The radially inner actuation reinforcement 24 is positioned radially inward of the radially outer actuation layer 26.

[0115] The hoop reinforcement 22 comprises at least one hooping layer, and here comprises one hooping layer 28. The hoop reinforcement 22 is composed of the hooping layer 28 here.

[0116] The crown reinforcement 16 bears radially on the tread 14. In this case, the hoop reinforcement 22, here the hooping layer 28, is arranged radially outside the operational reinforcement 20 and is therefore radially sandwiched between the operational reinforcement 20 and the tread 14. Preferably, the hoop reinforcement 22 has an axial width at least as large as the axial width of the operational reinforcement 20; in this particular case in the embodiment shown in Figure 1, the hoop reinforcement 22 can be envisaged as having an axial width greater than the axial width of the operational reinforcement 20.

[0117] The tire 10 includes two sidewalls 30 extending radially inward from the crown 12. The tire 10 further includes two beads 32 radially inward from the sidewalls 30. Each sidewall 30 connects a respective bead 32 to the crown 12.

[0118] The tire 10 comprises a carcass reinforcement 34 secured within each bead 32, in this case wrapped around a bead wire 33. The carcass reinforcement 34 extends radially inward of the crown 12 within each sidewall 30. The crown reinforcement 16 is disposed radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass layer, here a single carcass layer 36. In this particular case, the carcass reinforcement 34 consists of a single carcass layer 36.

[0119] Each working layer 24, 26, hooping layer 28, and carcass layer 36 comprises an elastomeric matrix having embedded therein one or more filamentary reinforcing elements of the corresponding layer, as will now be described with reference to FIG.

[0120] The hoop reinforcement 22, here a hooping layer 28, is axially bounded by two axial edges 28A, 28B of the hoop reinforcement 22. The hoop reinforcement 22 comprises one or more hooping filamentary reinforcing elements 280, which are circumferentially spirally wound so as to extend axially from the axial edge 28A of the hoop layer 28 to the other axial edge 28B in a main direction D0 of each hooping filamentary reinforcing element 280. The main direction D0 forms an angle AF with the circumferential direction X of the tire 10 that is less than or equal to 10°, preferably less than or equal to 7°, and more preferably less than or equal to 5°, in absolute value. In this case, AF=-5°. The hooping layer 28 comprises a density of 98 hooping filamentary reinforcing elements per decimeter, measured perpendicular to the direction D0.

[0121] The radially inner working layer 24 is delimited axially 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 one another along the main direction D1. Similarly, the radially outer working layer 26 is delimited axially 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 one another 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, respectively, directed oppositely with the circumferential direction X of the tire 10. Each main direction D1, D2 forms with the circumferential direction X of the tire 10 an angle AT1, AT2, respectively, that is strictly greater than 10° in absolute value, preferably in the range of 15° to 50°, more preferably in the range of 15° to 30°. In this case, AT1=-26° and AT2=+26°.

[0122] 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 its axial edge 36A to the other axial edge 36B along a main direction D3 that forms an angle AC with the circumferential direction X of the tire 10 that is greater than or equal to 60° in absolute value, preferably ranging from 80° to 90°, here AC=+90°.

[0123] Conventionally, each hooping filamentary reinforcing element 280 comprises two multifilament strands, each made of a spun aliphatic polyamide yarn, in this case a nylon monofilament with a yarn count equal to 140 tex, each of which is individually twisted helically in one direction at 250 turns per meter and in the opposite direction at 250 turns per meter, and which are wound helically around each other. As a variant, it is conceivable to use a hooping filamentary reinforcing element 280 comprising one multifilament strand of a spun aliphatic polyamide yarn, here a nylon monofilament with a yarn count equal to 140 tex, and one multifilament strand of a spun aromatic polyamide yarn, here an aramid monofilament with a yarn count equal to 167 tex, each of which is helically twisted 290 times per meter in one direction and then helically twisted 290 times per meter in the opposite direction. The two multifilament strands are helically wound around each other. This variant results in AT1 = -29° and AT2 = +29°.

[0124] Each working filamentary reinforcing element 180 is an assembly of two steel monofilaments, each having a diameter equal to 0.30 mm and wound helically with a pitch of 14 mm. As a variant, it is contemplated that an assembly of six steel monofilaments may be used, comprising an inner layer of two monofilaments, each having a diameter equal to 0.23 mm, wound helically around one another in a first direction, e.g., the Z direction, with a pitch of 12.5 mm, and an outer layer of four monofilaments wound helically around one another around the inner layer with a pitch of 12.5 mm in a second direction opposite the first direction, e.g., the S direction. In another variant, each working filamentary reinforcing element 180 is composed of a steel monofilament having a diameter equal to 0.30 mm. More generally, the steel monofilaments have a diameter ranging from 0.25 mm to 0.32 mm.

[0125] Conventionally, each carcass filamentary reinforcing element 340 comprises two multifilament strands, each composed of a spun polyester yarn, here a monofilament of PET, each of which is individually helically twisted in one direction at 240 turns per meter and in the opposite direction at 240 turns per meter. Each of these multifilament strands has a yarn count equal to 220 tex. In other variants, it is contemplated that a yarn count equal to 144 tex and a twist equal to 420 turns per meter, or a yarn count equal to 334 tex and a twist equal to 270 turns per meter, could be used.

[0126] 1, 3, and 4, the tread 14 comprises a tread surface 38 which brings it into contact with the road surface. The tread surface 38 is intended to be in contact with the road surface when the tire 10 is running along the road surface and is bounded axially by first and second axial edges 41, 42 which pass through points N located on either side of the median plane M such that the angle between a tangent T of the tread surface 38 passing through points N and a straight line R parallel to the axial direction Y is equal to 30°.

[0127] 1 and 3-5, the tread 14 comprises an axially central portion P0 and first and second axial lateral portions P1, P2 axially disposed axially outward of the axially central portion P0, one on each side of the axially central portion P0 with respect to the median plane M of the tire 10.

[0128] The axially central portion P0 has an axial width L0 that is 50% of the axial width L of the tread surface 38 of the tire 10 when new, preferably greater than or equal to 60%, less than or equal to 80%, and preferably less than or equal to 70%.

[0129] Each of the first and second axial lateral portions P1, P2 has an axial width L1 that is less than or equal to 25%, preferably less than or equal to 20%, and greater than or equal to 5%, preferably greater than or equal to 10%, of the axial width L of the tread surface 38 of the tire 10 when new.

[0130] The ratio of the axial width L0 of the central portion P0 to the axial width L1, L2 of each of the first and second lateral axial portions P1, P2 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.

[0131] In this case, L0=140 mm, L1=L2=33 mm, and L=206 mm.

[0132] The axially central portion includes first, second, third, and fourth major circumferential grooves, designated by reference numerals 52, 54, 56, and 58, respectively. The first and second grooves 52, 54 are axially disposed, one on each side of the median plane M of the tire 10, and are the major circumferential grooves furthest axially outward of the tread 14.

[0133] Referring to Figures 3 to 5, each of the first, second, third, and fourth major circumferential grooves 52, 54, 56, 58 is bounded by an axially outer edge, designated by reference numerals 521, 541, 561, 581, respectively, at a radial dimension equal to the radial dimension of the tread surface 38, and an axially inner edge, designated by reference numerals 522, 542, 562, 582, respectively.

[0134] 4 and 5, each main circumferential groove 52, 54, 56, 58 is bounded axially by an axially inner surface Fr1 and an axially outer surface Fr2 that axially bound each main circumferential groove 52, 54, 56, 58 at a radial dimension inside the radial dimension of the tread surface 38. Each main circumferential groove 52, 54, 56, 58 is bounded radially inward by a bottom surface Frd.

[0135] Each main circumferential groove 52, 54, 56, 58 is chamfered, i.e., each main circumferential groove 52, 54, 56, 58 is arranged so that it is connected to at least one of the axial inner surface Fr1 and the axial outer surface Fr2, in this case each of the axial inner edges 522, 542, 562, 582 and axial outer edges 521, 541, 561, 581 of the main circumferential groove 52, 54, 56, 58, respectively, by a chamfer Cf.

[0136] Each of the main circumferential grooves 52, 54, 56, 58 is designated by the reference numerals Hr2, Hr4, Hr6, and Hr8, and has a depth ranging from 4.0 mm to the tread pattern height Hs, particularly preferably from 5.0 mm to the tread pattern height Hs, and even more preferably from 5.5 mm to the tread pattern height Hs. Each depth Hr2, Hr4, Hr6, and 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.

[0137] Each of the main circumferential grooves 52, 54, 56, 58 is designated by the reference numerals Lr2, Lr4, Lr6, and Lr8, respectively, and has a width 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 even more preferably in the range of 8.0 mm to 15.0 mm, where Lr2=Lr4=10.0 mm and Lr6=Lr8=12.5 mm.

[0138] The axially central portion P0 extends in the axial direction from the axially outer edge 521 of the first main circumferential groove 52 to the axially outer edge 541 of the second main circumferential groove .

[0139] The axially central portion P0 comprises first, second, and third central ribs, respectively designated by reference numerals 62, 64, and 66. Each central rib 62, 64, and 66 is axially bounded by two major circumferential grooves, here two of the first, second, third, and fourth major circumferential grooves 52, 54, 56, and 58.

[0140] The first central rib 62 is disposed so as to be included in the axial direction between the first main circumferential groove 52 and the third main circumferential groove 56. In this case, the first central rib 62 extends in the axial direction 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.

[0141] The second central rib 64 is disposed axially between the third major circumferential groove 56 and the fourth major circumferential groove 58. In this case, the second central rib 64 extends axially from the inner axial edge 562 of the third major circumferential groove 56 to the inner axial edge 582 of the fourth major circumferential groove 58.

[0142] The third central rib 66 is disposed axially between the fourth major circumferential groove 58 and the second major circumferential groove 54. In this case, the third central rib 66 extends axially from the outer axial edge 581 of the fourth major circumferential groove to the inner axial edge 542 of the second major circumferential groove 54.

[0143] Each central rib 62, 64, 66, designated by the reference numerals Ln2, Ln4, and Ln6, has an axial width that is less than or equal to 30%, preferably less than or equal to 25%, and greater than or equal to 10%, preferably greater than or equal to 15%, of the axial width L0 of the axial central portion P1. Each axial width Ln2, Ln4, and Ln6 ranges from 20 mm to 40 mm, preferably 25 mm to 35 mm. In this case, Ln2 = Ln4 = Ln6 = 29.5 mm.

[0144] The axially central portion P0 comprises at least one additional circumferential notch formed in one of the central ribs 62, 64, 66. In this case, each central rib 62, 64, 66 comprises an additional circumferential notch 72, 74, 76, respectively. Each additional circumferential notch 72, 74, 76 is axially disposed between two circumferential grooves 52 and 56, 56 and 58, 58 and 54, respectively, that comprise a respective central rib 62, 64, 66 therebetween.

[0145] Each additional circumferential notch 72, 74, 76 has a depth 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 notch 72, 74, 76 has an axial width Lc2, Lc4, Lc6, respectively, in the range of 4% to 15% of the respective axial width Ln2, Ln4, Ln6, preferably 4% to 10%. Each axial width Lc2, Lc4, Lc6 ranges from 1.0 mm to 4.0 mm, where Lc2 = Lc4 = Lc6 = 2.0 mm. Each additional circumferential notch 72, 74, 76 has a depth Hc2, Hc4, Hc6, respectively, less than or equal to 3.0 mm, preferably in the range of 1.0 mm to 3.0 mm, where Hc2=Hc4=Hc6=1.0 mm.

[0146] 9, each central rib 62, 64, 66 has an axial portion P62, P64, P66, respectively, and here is composed of each axial portion P62, P64, P66. Each axial portion P62, P64, P66 has an axial width equal to each axial width Ln2, Ln4, and Ln6. Each axial portion P62, P64, P66 does not include a transverse notch 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 width Ln2, Ln4, and Ln6 of each central rib 62, 64, 66, so as to satisfy one of conditions I, II, and III, here only condition I. The axial width of all of the axial portions P62, P64, P66, here 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, here equal to 100% of each axial width Ln2, Ln4, and Ln6.

[0147] Referring to FIG. 3, the first axial lateral portion P1 is disposed to extend axially from the first axial edge 41 of the tread surface 38 to the axial outer edge 521 of the first major circumferential groove 52.

[0148] The second axial lateral portion P2 is disposed to extend axially from the second axial edge 42 of the tread surface 38 to the axial outer edge 541 of the second major circumferential groove 54.

[0149] 4-6, each of the first and second axial transverse portions P1, P2 includes an additional circumferential notch 82, 84 formed therein. The additional circumferential notch 82 is axially disposed between the first circumferential groove 52 and the first axial edge 41 of the tread surface 38. The additional circumferential notch 84 is axially disposed between the second circumferential groove 54 and the second axial edge 42 of the tread surface 38.

[0150] Each additional circumferential notch 82, 84 has a depth strictly less than 50% of the tread pattern height Hs, preferably less than 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 notch 82, 84 has an axial width Ll2, Ll4, respectively, in the range of 3% to 15% of the respective axial width Ll, L2, preferably 3% to 10%. Each axial width Ll2, Ll4 is in the range of 1.0 mm to 4.0 mm, where Ll2 = Ll4 = 2.0 mm. Each additional circumferential notch 82, 84 has a depth Hl2, Hl4, respectively, less than or equal to 3.0 mm, preferably in the range of 1.0 mm to 3.0 mm, where Hl2 = Hl4 = 1.0 mm.

[0151] 6, each axial lateral portion P1, P2 includes a transverse cutout 90, 90' having a depth greater than or equal to 20% of the tread pattern height Hs. In this particular case, all of the transverse cutouts 90, 90' in each axial lateral portion P1, P2 have a depth Ht greater than or equal to 20%, preferably 30%, and more preferably 40% of the tread pattern height Hs. Each transverse cutout 90, 90' has a depth Ht ranging from 2.0 mm to the tread pattern height Hs, preferably ranging from 4.0 mm to the tread pattern height Hs, and even more preferably ranging from 5.0 mm to the tread pattern height Hs, where Ht=6.0 mm.

[0152] 7 and 8, each transverse cutout 90, 90' is circumferentially bounded by a leading edge 901 and a trailing edge 902 at a radial dimension equal to the radial dimension of the tread surface 38. Each transverse cutout 90, 90' is circumferentially bounded by a front face Ft1 and a trailing face Ft2 at a dimension radially inward of the radial dimension of the tread surface 38. Each transverse cutout 90, 90' is bounded radially inward by a bottom face Ftd. Each transverse cutout 90, 90' is chamfered, i.e., each transverse cutout 90, 90' is positioned such that each of the front face Ft1 and the trailing face Ft2 is connected to each of the leading edge 901 and the trailing edge 902 of each transverse cutout 90, 90', respectively, by a chamfer Cf. Each transverse notch 90, 90' extends axially from the outer axial end E1 to the inner axial end E2 as far as the inner axial end E2, defining a total curvilinear length TI of each transverse notch 90, 90' and an axial length La, La' of each transverse notch 90, 90'.

[0153] 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 a four-component group of transverse cuts 90 comprising transverse cuts 92, 94, 96, 98 formed in the first axial transverse portion P1 and a three-component group of transverse cuts 90' comprising transverse cuts 92', 94', 96' formed in the second axial transverse portion P2. These cuts have different widths and are irregularly distributed around the circumferential direction to avoid shrill noise and maintain tire uniformity. The width of each transverse cut 90, 90' is less than or equal to 2.0 mm, preferably ranging from 0.5 mm to 2.0 mm. Thus, each transverse notch 92, 94, 96, 98, 92', 94', 96' has a width Lt2, Lt4, Lt6, Lt8, Lt2', Lt4', Lt6' such that Lt2=Lt2'=1.2 mm, Lt4=Lt4'=Lt8=1.5 mm, and Lt6=Lt6'=0.8 mm.

[0154] 3, 7 and 8, the first axial transverse portion P1 comprises transverse cutouts 92, 94, 96, 98 each comprising a main portion designated by reference numerals 921, 941, 961, 981, respectively, and a complementary portion designated by reference numerals 922, 942, 962, 982, respectively, the main and complementary portions being separated from each other by discontinuities 923, 943, 963, 983 in the curvature of each front face Ft1 and rear face Ft2. Each supplemental portion 922, 942, 962, 982 is disposed axially outward of 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, which here equals the respective width Lt2, Lt4, Lt6, Lt8. Each main portion 921, 941, 961, 981 extends over a major curvilinear length Tp that is strictly greater than 50% of the total curvilinear length TI of each transverse cutout 92, 94, 96, 98. Each supplemental portion 922, 942, 962, 982 extends over a supplemental curvilinear length Tc that is strictly less than 50% of the total curvilinear length TI of each transverse cutout 92, 94, 96, 98.

[0155] Each transverse notch 92, 94, 96, 98 has an axial length La that is greater than or equal to 20%, preferably 30%, more preferably 50%, and even more preferably 75% of the axial width L1 of the first axial transverse portion P1, in this case La=42 mm.

[0156] The transverse cuts 90, here made up of transverse cuts 92, 94, 96, 98 and 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 lateral axial portion P1, number N=125 around the circumference of the tire 10. In a variant of the first embodiment, N=98.

[0157] As can be seen in FIG. 3, the second axial transverse portion P2 comprises transverse notches 92', 94', 96' each consisting of a main portion having a curvilinear length equal to the curvilinear length of the notch.

[0158] Each transverse cutout 92', 94', 96' has an axial length La' that is greater than or equal to 20%, preferably 30%, more preferably 50%, and even more preferably 75% of the axial width L2 of the second axial transverse portion P2, in this case La2'=42 mm.

[0159] The transverse cuts 90' made up of the transverse cuts 92', 94', 96' and 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 lateral axial portion P2 are N'=125 in number around the circumference of the tire 10, or N'=98 in the variant described above.

[0160] Each transverse cutout 90, 90' of each of the first and second axial transverse portions P1, P2 is at least partially closed by a connecting bridge 100 connecting the front face Ft1 and the rear face Ft2 and forming the axially inner end E2 of each transverse cutout 90, 90', where each connecting bridge 100 is arranged to completely block communication between each transverse cutout 90, 90' and each of the first and second main circumferential grooves 52, 54 when the transverse cutout penetrates into the contact patch when the tire is in contact with the road surface on which it is traveling.

[0161] 9, each first and second axial transverse portion P1, P2 comprises a first axial portion P11, P21 respectively comprising N, N' transverse cutouts 90, 90', and a second axial portion P12, P22 respectively consisting of a connecting bridge 100. Each second axial portion P12, P22 is arranged axially inward of each first axial portion P11, P21.

[0162] Each axial portion P11, P21 has an axial width greater than or equal to 70%, preferably 80%, more preferably 90%, and here equal to 91% of the axial width of the respective transverse axial portion P1, P2. In this case, each first axial portion P11, P21 has an axial width equal to 30 mm. To complement this, each second axial portion P12, P22 has an axial width equal to 3 mm. Each axial portion P11, P21 only satisfies condition III in that π×OD / N≦24 mm. Furthermore, π×OD / N≧10 mm. In this particular case, π×OD / N=17 mm. In the above-mentioned variant with N=98, π×OD / N≦24 mm and π×OD / N≧10 mm, more specifically π×OD / N=22 mm, are true.

[0163] In the first embodiment, to limit the transition zone, each central rib 62, 64, 66 and each first and second axial transverse portion P1, P2 must satisfy one of conditions I, II, and III. Only one and having axial widths greater than or equal to 70%, preferably 80%, and more preferably 90% of the axial width of each central rib 62, 64, 66 and each first and second axial transverse portion P1, P2, respectively.

[0164] The surface area porosity of the tread 14 ranges from 27% to 45%, preferably from 30% to 40%, and is here equal to 36%. The volume porosity of the tread 14 ranges from 17% to 35%, preferably from 20% to 30%, and is here equal to 24%.

[0165] The surface area porosity of each of the first and second axial transverse portions P1, P2 ranges from 20% to 30% and is here equal to 25%. The volume porosity of each of the first and second axial transverse portions P1, P2 ranges from 5% to 10% and is here equal to 8%.

[0166] 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%.

[0167] 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%.

[0168] The ratio of the surface area porosity of each central rib 62, 64, 66 to the surface area porosity of each first and second axial transverse portion P1, P2 is less than or equal to 0.35, preferably less than or equal to 0.30, and more preferably in the range of 0.10 to 0.30, here equal to 0.28. The ratio of the volume porosity of each central rib 62, 64, 66 to the volume porosity of each first and second axial transverse portion P1, P2 is less than or equal to 0.20, preferably less than or equal to 0.15, and more preferably in the range of 0.10 to 0.15, here equal to 0.13.

[0169] A tire according to a second embodiment of the invention will now be described below with reference to Figure 10. Elements similar to those of the first embodiment are indicated by the same reference numerals.

[0170] Unlike in the first embodiment, the central rib 64 does not have a circumferential notch with a depth strictly less than 50% of the tread pattern height. In this case, the central rib does not include the additional circumferential notch 74.

[0171] Furthermore, the central rib 64 is formed so as to satisfy each of the conditions I, II, and III. Only oneIn this particular case, the central rib 64 has, on the one hand, a first axial portion P641 whose axial width is equal to 50% of the axial width Ln4 of the central rib 64 and which satisfies only condition III, and, on the other hand, a second axial portion P642 whose axial width is equal to 50% of the axial width Ln4 of the central rib 64 and which satisfies only condition I. Each of the overall axial widths of the first and second axial portions P641 and P642 of the central rib 64 satisfies one of conditions I, II, and III. Only one and is 70%, preferably 80%, more preferably 90% of the axial width of the central rib 64, and here is 100% of the axial width Ln4.

[0172] More specifically, the axial portion P641 comprises transverse cutouts 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%, here equal to 50%, of the axial width of the central rib 64. The cutouts 91 number N=125 around the circumference of the tire. The total number of N transverse cutouts 91 is arranged such that π×OD / N≦24 mm, so as to satisfy only condition III. In a variation of this second embodiment, N=98, and π×OD / N≦24 mm also holds.

[0173] Unlike the first embodiment, the central rib 64 has a transition zone between the first axial portion P641 and the second axial portion P642, and the axial widths of the first and second axial portions P641 and P642 are such that the central rib 64 satisfies one of conditions I, II, and III. Only one and does not include any axial portion having an axial width greater than or equal to 70% of the axial width of the central rib 64.

[0174] A tire according to a third embodiment of the present invention will now be described below with reference to Figure 11. Elements similar to those of the prior art embodiment are indicated by the same reference numerals.

[0175] Unlike the first embodiment, each central rib 62, 64, 66 does not have any circumferential notches having a depth strictly less than 50% of the tread pattern height. In this case, each central rib 62, 64, 66 does not include each additional circumferential notch 72, 74, 76.

[0176] Furthermore, as in the second embodiment, each of the central ribs 62, 64, 66 satisfies one of conditions I, II, and III. Only one In this particular case, each of the central ribs 62, 64, 66 has axial portions P621, P641, P661 which have an axial width equal to 50% of the axial width Ln2, Ln4, Ln6 of each of the central ribs 62, 64, 66 and which satisfy only condition III, and on the other hand, has axial portions P622, P642, P662 which have axial widths equal to 50% of the axial width Ln2, Ln4, Ln6 of each of the central ribs 62, 64, 66 and which satisfy only condition I. Therefore, Only one The overall axial width of the first and second axial portions P621 and P622, P641 and P642, P661 and P662 of each central rib 62, 64, 66 satisfying the following is greater than or equal to 70%, preferably 80%, more preferably 90% of the axial width of the central rib 64, and here equal to 100% of each axial width Ln2, Ln4, Ln6.

[0177] A tire according to a fourth embodiment of the present invention will now be described with reference to Figure 12. Elements similar to those of the prior art embodiment are indicated by the same reference numerals.

[0178] Unlike in the first embodiment, the central rib 64 does not have a circumferential notch with a depth strictly less than 50% of the tread pattern height. In this case, the central rib does not include the additional circumferential notch 74.

[0179] Furthermore, the central rib 64 is formed so as to satisfy each of the conditions I, II, and III. Only oneand a central portion P642 that does not satisfy any of conditions I, II, or III.

[0180] In this particular case, the overall axial width of axial portions P641 and P643, each satisfying one of conditions I, II, or III, here only condition III, is greater than or equal to 70% of the axial width of the central rib 64, here equal to 75% of the axial width Ln4, such that on the one hand, axial portion P641 has an axial width equal to 50% of the axial width Ln4 of the central rib 64 and satisfies only condition III, and on the other hand, axial portion P643 has an axial width equal to 25% of the axial width Ln4 of the central rib 64 and satisfies only condition III.

[0181] Furthermore, unlike the second and third embodiments, the central rib 64 is formed so as to satisfy one of conditions I, II, and III, respectively. Only one However, the entire axial portions P641, P643 of the fourth embodiment satisfy one of conditions I, II, and III, here only condition III.

[0182] Unlike in the first embodiment, the central rib 64 comprises two transition zones between the various axial portions P641, P642, and P643, and the axial widths of the axial portions P641, P642, and P643 are such that the central rib 64 satisfies one of conditions I, II, and III. Only one and does not include any axial portion having an axial width greater than or equal to 70% of the axial width of the central rib 64.

[0183] More specifically, each axial portion P641, P643 includes a transverse cutout 91, 93 having a depth Ht greater than or equal to 20% of the tread pattern height Hs and an axial length Lb, Lc greater than or equal to 20% of the axial width of the central rib 64, here equal to 50% and 25%, respectively. The notches 91, 93 are each circumferentially spaced N1 = N3 = 125 in number. The total number of N1 transverse cutouts 91 and the total number of N3 transverse cutouts 93 are arranged such that π × OD / N1 ≦ 24 mm and π × OD / N3 ≦ 24 mm, satisfying only condition III. This variation of the fourth embodiment results in N1 = N3 = 98, and therefore π × OD / N1 ≦ 24 mm and π × OD / N3 ≦ 24 mm, also satisfying only condition III.

[0184] Axial portion P642 does not satisfy any of conditions I, II, or III. In particular, axial portion P642 comprises N transverse notches 95 throughout the circumferential direction of the tire of FIG. 12, where these N=65 transverse notches 95 have a depth Ht greater than or equal to 20% of the tread pattern height Hs and an axial length greater than or equal to 20%, here equal to 25%, of the axial width Ln4 of the central rib 64, but where the total of the N transverse notches 95 is arranged such that 24 mm<π×OD / N2<40 mm.

[0185] A tire according to a fifth embodiment of the present invention will now be described with reference to Figure 13. Elements similar to those of the prior art embodiment are indicated by the same reference numerals.

[0186] Unlike the fourth embodiment, the central rib 64 is formed so as to satisfy the conditions I, II, and III. Only one and a central portion P642 that does not satisfy any of conditions I, II, or III.

[0187] In this particular case, the overall axial width of axial portions P641, P643, and P644, each satisfying one of conditions I, II, and III, here only conditions I, II, and III, is greater than or equal to 70% of the axial width of the central rib 64, here equal to 75% of the axial width Ln4, so that on the one hand, axial portion P641 has an axial width equal to 25% of the axial width Ln4 of the central rib 64 and satisfies only condition III, on the other hand, axial portion P643 has an axial width equal to 25% of the axial width Ln4 of the central rib 64 and satisfies only condition I, and finally axial portion P644 has an axial width equal to 25% of the axial width Ln4 of the central rib 64 and satisfies only condition II.

[0188] More specifically, the axial portion P641 includes transverse cutouts 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%, here equal to 25%, of the axial width of the central rib 64. The cutouts 91 number N1=125 around the circumference of the tire. The total number of N1 transverse cutouts 91 is arranged such that π×OD / N1≦24 mm so as to satisfy only condition III. A variation of this fifth embodiment results in N1=98 such that π×OD / N1≦24 mm so as to satisfy only condition III.

[0189] As in the fourth embodiment, the axial portion P642 does not satisfy any of the conditions I, II, or III.

[0190] 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. These cutouts 97 number N4=25 around the circumference of the tire. All of the transverse cutouts 97 of the axial portion P644 are arranged such that π×OD / N4≧40 mm, preferably such that π×OD / N4≧60 mm, and even more preferably such that π×OD / N4≧80 mm.

[0191] It should be noted that, unlike the first embodiment, the central rib 64 comprises three transition zones between the various axial portions P641, P642, P643 and P644, and the axial widths of the axial portions P641, P642, P643 and P644 are such that the central rib 64 satisfies only one of conditions I, II and III and does not include any axial portion having an axial width greater than or equal to 70% of the axial width of the central rib 64.

[0192] Comparative Test

[0193] Tests were conducted on a tire 10 according to the first embodiment of the present invention, and also on a control tire W not according to the present invention, which, unlike the tire 10 according to the first embodiment, has axial portions P62, P64, P66 each having a depth greater than or equal to 20% of the tread pattern height Hs and an axial width greater than or equal to 20% of the axial width Ln2, Ln4, and Ln6 of each central rib 62, 64, 66, and therefore each of these axial portions P62, P64, P66 has a transverse notch that satisfies condition III.

[0194] During these tests, the vehicle was fitted with four identical tyres 10 or W inflated to 2.5 bar and subjected to a load equal to 470 daN to measure the noise generated by the tyres tested in accordance with UNECE regulation 51-03.

[0195] The first test measured the exterior noise generated by the tire tested at a constant speed, i.e., zero acceleration. The second test measured the exterior noise generated by the tire tested during an acceleration phase with an acceleration equal to 3 m.s-2. The results are collated in Table 1 below. In this table, the noise generated by tire W at a constant speed is designated R, and that generated during the acceleration phase is designated R'. TIFF0007745572000001.tif23155 Table 1

[0196] It should be noted that the tire 10 according to the invention allows a significant reduction in the exterior noise generated by the tire, whether at constant speed or in the acceleration phase.

[0197] The present invention is not limited to the above-described embodiments.

[0198] Specifically, without departing from the scope of the present invention, a first central rib is included axially between the first and third major circumferential grooves; a second central rib is included axially between the second and third major circumferential grooves; It is possible to envisage an axially central portion comprising first, second and third main circumferential grooves and first and second central ribs arranged as follows: [Explanation of symbols]

[0199] 10 Tires 52, 54, 56, 58 Main circumferential groove 62, 64, 66 central rib 72, 74, 76 Circumferential notch 90, 90' transverse notch

Claims

1. A tire (10) for a passenger vehicle, comprising a tread (14) having an outer diameter OD and intended to come into contact with a road surface when the tire (10) is in motion through a tread surface (38) axially bounded by first and second axial edges (41, 42) of the tread surface, The tread (14) an axially central portion (P0) having main circumferential grooves (52, 54, 56, 58) having a depth (Hr) greater than or equal to 50% of a tread pattern height (Hs) including at least first and second main circumferential grooves (52, 54), one on each side of a median plane (M) of the tire (10), the first and second main circumferential grooves (52, 54) being the main circumferential grooves axially furthest outward from the tread (14); an axially central portion (P0) extending axially from the axially outer edge (521) of the main circumferential groove (52) as far as the axially outer edge (541) of the second main circumferential groove (54), the axially central portion (P0) comprising at least one central rib (62, 64, 66), the or each central rib (62, 64, 66) being axially separated 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); first and second axial lateral portions (P1, P2) axially arranged outside the axial central portion (P0), one on each side of the axial central portion (P0) with respect to the median plane (M) of the tire (10), the first axial lateral portion (P1) extends axially from the first axial edge (41) of the tread surface (38) to the axial outer edge (521) of the first main circumferential groove (52); the second axial lateral portion (P2) extends axially from the second axial edge (42) of the tread surface (38) to the axial outer edge (541) of the second main circumferential groove (54); The or each central rib (62, 64, 66) and each first and second axial transverse portion (P1, P2) comprises 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 each of the axial portions that each satisfy only one of the conditions I, II, III is the total axial width of one or more axial portions of the or each central rib (62, 64, 66) or of each first and second axial lateral portion (P1, P2) is greater than or equal to 70% of the axial width (Ln2, Ln4, Ln6, L1, L2) of the or each central rib (62, 64, 66) and of each first and second axial lateral portion (P1, P2); The condition is I - said axial portions (P62, P64, P66, P642, P643, P622, P662) do not comprise transverse notches (90, 90') having a depth (Ht) greater than or equal to 20% of said tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of said axial width (Ln2, Ln4, Ln6, L1, L2) of said central rib (62, 64, 66) or of said axial lateral portions (P1, P2), II - said axial portion (P644) comprises transverse notches (90, 90') having a depth (Ht) greater than or equal to 20% of said tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of said axial width of said central rib (62, 64, 66) or of said axial lateral portions (P1, P2), a set of N transverse notches (90, 90') of the axial portion having a depth (Ht) greater than or equal to 0% 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 transverse portion (P1, P2) is arranged so that π×OD / N≧40 mm; III - said axial portions (P11, P21, P621, P641, P661, P643) comprise transverse notches (90, 90') having a depth (Ht) greater than or equal to 20% of said tread pattern height (Hs) and an axial length (La, Lb, Lc) greater than or equal to 20% of said axial width (Ln2, Ln4, Ln6, L1, L2) of said central rib (62, 64, 66) or of said axial lateral portions (P1, P2), the N transverse notches (90, 90') of the central rib (62, 64, 66) or of the axial portions thereof having a depth (Ht) greater than or equal to 20% of the dot 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 transverse portions (P1, P2) are all arranged so that π×OD / N≦24 mm; and Condition I or II is satisfied by at least one of the axial portions of the central rib (62, 64, 66) or of one of the central ribs (62, 64, 66), or by one of the axial portions of the first axial transverse portion (P1), or by one of the axial portions of the second axial transverse portion (P2), condition III is satisfied by at least one of the axial portions of the central rib (62, 64, 66) or of one of the central ribs (62, 64, 66), or by one of the axial portions of the first axial transverse portion (P1), or by one of the axial portions of the second axial transverse portion (P2), the first and second axial transverse portions (P1, P2); Equipped with A tire (10) characterized in that

2. 2. A tire (10) according to claim 1, characterized in that at least one of the axial portions of the or each central rib (62, 64, 66) satisfies condition I or II, and at least one of the axial portions of each of the first and second axial lateral portions (P1, P2) satisfies condition III.

3. 3. A tire (10) according to claim 1, having a depth (La, Lb, Lc) 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 (L1, L2, Ln1, Ln4, Ln6) of the or each central rib (62, 64, 66) or of the or each axial lateral portion (P1, P2), and wherein the total of the N transverse notches (90, 90') of the or each central rib (62, 64, 66) or of the or each axial lateral portion (P1, P2) that satisfy condition III is arranged so that π × OD / N ≥ 10 mm.

4. 4. A tire (10) according to any one of claims 1 to 3, characterized in that the total axial width of the one or more axial portions of the or each central rib (62, 64, 66) and of each first and second axial lateral portion (P1, P2), each satisfying only one of conditions I, II, III, is greater than or equal to 80%, preferably 90%, of the axial width (Ln2, Ln4, Ln6, L1, L2) of the or each central rib (62, 64, 66) and of each first and second axial lateral portion (P1, P2).

5. 5. Tyre (10) according to any one of claims 1 to 4, characterized in that the or each central rib (62, 64, 66) or the first axial transverse portion (P1) or the second axial transverse portion (P2) comprises several axial portions each satisfying only one of conditions I, II, III, such that the entire axial portion of the or each central rib (62, 64, 66) or of the first axial transverse portion (P1) or of the second axial transverse portion (P2) satisfies only one of conditions I, II, III.

6. 6. A tyre (10) according to any one of claims 1 to 5, characterized in that the or each central rib (62, 64, 66) and each first and second axial lateral portion (P1, P2) comprises axial portions satisfying only one of conditions I, II and III, the axial width of which is greater than or equal to 70% of the axial width of the or each central rib (62, 64, 66) and of each first and second axial lateral portion (P1, P2).

7. 7. Tyre (10) according to any one of claims 1 to 6, characterized in that the surface area porosity of each of the first and second axial lateral portions (P1, P2) is in the range of 20% to 30%.

8. 8. Tyre (10) according to any one of claims 1 to 7, characterized in that the volume voids of each of the first and second axial transverse portions (P1, P2) are in the range of 5% to 10%.

9. 9. A tire (10) according to any one of claims 1 to 8, characterized in that the or each central rib (62, 64, 66) has a surface area porosity in the range of 5% to 10%.

10. 10. Tyre (10) according to any one of claims 1 to 9, characterized in that the or each central rib (62, 64, 66) has a volume void content in the range of 0.5% to 5%.

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