Tire comprising an optimized self-sealing product layer

Abstract

The tire comprises a tread, an inner sealant layer, a self-sealing product layer (80), the tread comprising a main circumferential incision (52, 54, 56, 58) and a rib (62, 64, 66, 68, 70), the self-sealing product layer (80) comprising: an axial portion extending in alignment with the main circumferential incision (52, 54, 56, 58) and having an average thickness Ea>0, an axial portion extending in alignment with the rib (62, 64, 66, 68, 70) and having an average thickness Eb≥0 of self-sealing product, Eb<Ea being satisfied.

Description

Technical Field

[0001] This invention relates to a tire. A tire is understood to mean an outer tire designed to form a cavity by cooperating with a supporting element (e.g., a rim), the cavity being pressurized to pressures greater than atmospheric pressure. The tire according to the invention has a substantially annular structure exhibiting rotational symmetry about the tire's main axis. Background Technology

[0002] EP2629964 discloses a tire including a tread designed to contact the ground via its surface during tire travel. The tread includes main circumferential cutouts and central ribs, each central rib being axially arranged between two adjacent main circumferential cutouts and defined axially by the two adjacent main circumferential cutouts.

[0003] The tire of EP2629964 includes an airtight inner layer and a self-sealing product layer. The airtight inner layer is designed to form an airtight cavity relative to the inflation gas when the tire is mounted on a mounting support (e.g., a rim). The self-sealing product layer extends circumferentially inside a portion of the airtight inner layer.

[0004] In the event of a tire puncture caused by a perforating object, the self-sealing product layer can seal the hole created by the puncture under the pressure inside the tire. This is because, under the pressure inside the tire, the self-sealing product flows towards the hole through which air escapes, thereby sealing it and re-establishing an airtight seal relative to the inflation gas. Many self-sealing products have been described in the prior art, particularly in US4426468, EP1090069, WO99 / 62998, US4113799, US4115172, US4913209, US5085942, US5295525, FR2955587, and EP2167329.

[0005] Although self-sealing layers have proven effective in preventing punctures, their presence inevitably makes tires heavier than those without them. Summary of the Invention

[0006] The object of the present invention is to provide a tire with a sealing product layer that is as lightweight as possible and whose self-sealing product layer is substantially as effective as the self-sealing product layer of prior art tires in preventing punctures.

[0007] Therefore, one subject of the present invention is a tire, the tire comprising:

[0008] - Tread, the tread comprising:

[0009] - At least one circumferential cut, referred to as the main circumferential cut, having a depth Ha satisfying Ha / Hs≥50%, where Hs is the tread height.

[0010] - At least one rib-like part

[0011] -Airtight inner layer

[0012] - A self-sealing product layer that extends circumferentially inward on a portion of the airtight inner layer.

[0013] The self-sealing product layer comprises, over at least 50% of its circumferential length:

[0014] - An axial portion extending along the axial direction aligned with the main circumferential cut, wherein the axial portion has an average thickness Ea > 0 for the self-sealing product.

[0015] - An axial portion extending axially aligned with the ribs, said axial portion having an average thickness Eb≥0 for the self-sealing product, and satisfying Eb <Ea。

[0016] The inventors of this invention have determined that the axial portions of the tread with the greatest risk of perforation are those with relatively small tread thicknesses. According to the invention, these axial portions include primary circumferential cuts having a depth at least equal to half the tread pattern height. Therefore, the invention provides a relatively high average thickness Ea of the self-sealing product aligned with these primary circumferential cuts, thereby ensuring the high effectiveness of the self-sealing product layer against perforations occurring in the primary circumferential cuts.

[0017] To reduce tire weight, the inventors have determined that the rib portion of a tire with a tread thickness greater than that of the tread portion located radially inside the main circumferential cut has a lower risk of puncture. This is because, on the one hand, if the puncture object is relatively short, the tread thickness protects the tire from puncture, and on the other hand, a relatively larger tread thickness provides greater resistance to puncture than a relatively smaller thickness. Therefore, the present invention provides a relatively small (or even zero) average thickness Eb of a self-sealing product aligned with the rib portion, thereby enabling a significant reduction in tire weight.

[0018] In the event of a tire puncture caused by a perforating object, the self-sealing product layer can seal the hole created by the puncture under the pressure inside the tire. This is because, under the pressure inside the tire, the self-sealing product flows towards the airflow through the hole, thereby sealing it and re-establishing an airtight seal relative to the inflation gas.

[0019] Advantageously, in some embodiments, the self-sealing product layer consists of a single self-sealing product. In these embodiments, when the tire is mounted on a mounting support (e.g., a rim), the self-sealing product is arranged to contact the inflation gas present in a cavity at least partially defined by the self-sealing product and the tire's mounting support.

[0020] According to the present invention, in some embodiments, there may be one or more main circumferential cuts and one or more axial portions having relatively large non-zero thickness (each axial portion extending axially aligned with the main circumferential cut or a main circumferential cut), as well as one or more ribs and one or more axial portions having relatively small non-zero thickness (each axial portion extending axially aligned with the rib or a rib).

[0021] In other embodiments, there may be one or more main circumferential cuts and one or more axial portions with relatively large non-zero thickness (each axial portion extending axially aligned with the main circumferential cut or a main circumferential cut), as well as one or more ribs and one or more axial portions with zero thickness (each axial portion extending axially aligned with the rib or a rib).

[0022] In other embodiments, there may be one or more main circumferential cuts and one or more axial portions with relatively large non-zero thickness (each axial portion extending axially aligned with a main circumferential cut), a plurality of ribs and one or more axial portions with relatively small non-zero thickness (each axial portion extending axially aligned with a rib), and one or more axial portions with zero thickness (each axial portion extending radially aligned with a rib).

[0023] A circumferential cut, or each circumferential cut, is referred to as a primary circumferential cut because it has a relatively large depth Ha relative to other supplementary circumferential cuts (which may optionally be present on the tire tread and have a relatively small depth), thus creating a smaller risk of puncture.

[0024] The axial portion of the self-sealing product layer, aligned with the main circumferential cutout or rib of the tread, is defined by two circumferential planes perpendicular to the tire's axis of rotation, each plane passing through the axial end of the main circumferential cutout or rib. Therefore, if the axial width of the axial portion of the self-sealing product layer, referred to as the thick axial portion, is greater than the axial width of the main circumferential cutout, only a portion of the thick axial portion of the self-sealing product layer aligns with the main circumferential cutout. If the axial width of the thick axial portion of the self-sealing product layer is less than the axial width of the main circumferential cutout, the entire thick axial portion of the self-sealing product layer aligns with the main circumferential cutout. Similarly, if the axial width of the axial portion of the self-sealing product layer, referred to as the thin axial portion, is greater than the axial width of the rib, only a portion of the thin axial portion of the self-sealing product layer aligns with the rib. If the axial width of the thin axial portion of the self-sealing product layer is less than the axial width of the rib, the entire thin axial portion of the self-sealing product layer aligns with the rib.

[0025] Without constituting a fundamental feature, the invention is advantageous in embodiments with particularly deep main circumferential cuts or each main circumferential cut (i.e., Ha / Hs≥75%, more preferably Ha / Hs≥90%).

[0026] Since the self-sealing product layer exhibits the essential features of the invention over at least 50% of its circumference, it is conceivable that embodiments of the tire may not have the self-sealing product layer over at most 50% of its circumference, or embodiments where the self-sealing product layer extends over 100% of its circumference but does not exhibit the essential features over 100% of its circumference. Of course, to maximize the effects of the invention, the self-sealing product layer exhibits the essential features of the invention over at least 75%, more preferably at least 95%, and ideally 100% of its circumference.

[0027] The present invention envisions embodiments in which the self-sealing product layer extends circumferentially over all or part of its circumferential length in a discontinuous or continuous manner. Preferably, and to ensure a high degree of effectiveness of the self-sealing product layer against perforations, each axial portion of the self-sealing product layer extending in alignment with the cut or each cut and the rib or each rib extends circumferentially continuously over at least 50%, preferably at least 75%, more preferably at least 95%, and ideally 100% of the circumferential length of the self-sealing product layer.

[0028] The present invention also envisions axial portions of a self-sealing product layer having variable thickness in the circumferential direction. However, in order to maximize mass gain and ensure the effectiveness of uniformity of the self-sealing product layer aligned with each main circumferential cut and each rib, the average thickness of each axial portion of the self-sealing product layer extending aligned with the main circumferential cut or each main circumferential cut and each rib or each rib is at least 50%, preferably at least 75%, more preferably at least 95%, and ideally 100% substantially constant along the circumferential direction of the circumferential length.

[0029] The average thicknesses Ea and Eb of the axial portions of the self-sealing product layer, extending axially aligned with the main circumferential cuts or ribs, are measured by averaging the thickness of the self-sealing product layer between the axial ends of the axial portions of the self-sealing product layer in multiple meridional cross-sectional planes, with the thicknesses measured, for example, in millimeters. In the preferred case where the average thickness is substantially constant along the circumferential direction, a smaller number of meridional cross-sectional planes will be used. If the average thickness is not constant along the circumferential direction, a larger number of meridional cross-sectional planes will be used, for example, 16, and the thicknesses measured in all meridional cross-sectional planes will be averaged. The thickness measured at a point is naturally the shortest straight-line distance between the radially outer and radially inner surfaces of the self-sealing product layer passing through that point. It should be noted that the cross-sections of the meridional cross-sectional planes are obtained without damaging the self-sealing product layer, thereby accurately measuring various geometric variables, especially the thickness. In particular, an extremely high-pressure water jet cutting method will be used.

[0030] On a brand new tire, the depth of the slit is the maximum radial distance between the bottom of the slit and its projection onto the ground when the tire is in motion. The maximum slit depth is called the tread height.

[0031] Cutouts represent grooves or sipes and create spaces leading to the tread surface.

[0032] A sipe or groove has two main characteristic dimensions on the tread surface: width and curve length, and satisfies that the curve length is at least twice the width. Therefore, a sipe or groove is defined by at least two principal side surfaces, which determine its curve length and are connected by a bottom surface. The two principal side surfaces are spaced apart from each other by a non-zero distance, referred to as the width of the sipe.

[0033] On a brand new tire, when the slit does not have a chamfer, the slit width is the maximum distance between the two main side surfaces measured on the radial side coinciding with the tread surface. When the slit has a chamfer, the slit width is the maximum distance between the two main side surfaces measured on the outermost radial side of the slit and the innermost radial side of the chamfer. The width is measured substantially perpendicular to the main side surfaces.

[0034] In itself, the axial width of the cut is measured in the axial direction of the tire, for example, in the meridional section plane of the tire.

[0035] The sipes satisfy the distance between the main side surfaces such that the main side surfaces defining the sipes are at least partially in contact with the contact surface, especially when the tire is brand new and under normal driving conditions, which in particular include the tire being under nominal load and under its nominal pressure.

[0036] The grooves satisfy the distance between the main side surfaces such that these main side surfaces do not come into contact with each other under normal driving conditions, which in particular include the tire being under nominal load and under its nominal pressure.

[0037] The incision can be horizontal or circumferential.

[0038] The lateral cut extends in an average direction forming an angle of strictly greater than 30°, preferably greater than or equal to 45°, with respect to the tire's circumferential direction. The average direction is the shortest curve connecting the two ends of the cut and parallel to the tread surface. The lateral cut can be continuous, meaning it is not interrupted by tread blocks or other cuts, such that the two principal side surfaces determining its length are uninterrupted along the length of the lateral cut. The lateral cut can also be discontinuous, meaning it is interrupted by one or more tread blocks and / or one or more other cuts, such that the two principal side surfaces determining its length are interrupted by one or more tread blocks and / or one or more other cuts.

[0039] A circumferential cut extends in an average direction forming an angle of less than or equal to 30°, preferably less than or equal to 10°, with respect to the tire's circumferential direction. The average direction is the shortest curve connecting the two ends of the cut and parallel to the tread surface. When the circumferential cut is continuous, the two ends overlap and are connected by a curve that forms a complete circle around the tire. A circumferential cut can be continuous, meaning it is not interrupted by tread blocks or other cuts, such that the two principal side surfaces determining its length are uninterrupted along the entire circumference of the tire. A circumferential cut can also be discontinuous, meaning it is interrupted by one or more tread blocks and / or one or more other cuts, such that the two principal side surfaces determining its length are interrupted along the entire circumference of the tire by one or more tread blocks and / or one or more other cuts.

[0040] When the circumferential cut is located outside the center plane of the tire, the side surfaces are referred to as the axial inner surface and the axial outer surface, with the axial inner surface arranged axially inside the axial inner surface at a given azimuth angle relative to the center plane.

[0041] Each circumferential cut includes an inner axial end and an outer axial end. Regardless of whether the circumferential cut has a chamfer, each inner axial end and outer axial end coincides with each axial edge of the circumferential cut on the tread surface, thus making contact with the ground when the tire is in motion.

[0042] In the case of a transverse cut, the side surfaces are referred to as the leading edge and the trailing edge, and for a given circumferential line, the edge of the leading edge enters the ground plane before the edge of the trailing edge.

[0043] In some implementations, the circumferential cut, or each circumferential cut (whether or not it is a primary circumferential cut), has a chamfer. The chamfer on the circumferential cut can be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a planar surface inclined relative to an axial inner surface and an axial outer surface, said planar surface continuing to the axial inner or axial outer edge defining the circumferential cut along the axial direction. A rounded chamfer is formed by a curved surface tangentially merged into its continuing axial inner or axial outer surface. The chamfer on the circumferential cut is characterized by its height and width, which are respectively equal to the radial distance and axial distance between a point common to the axial inner or axial outer surface from which the chamfer continues and the axial inner or axial outer edge defining the circumferential cut along the axial direction.

[0044] In some embodiments, the transverse cuts, or each transverse cut, have a chamfer. In other words, each transverse cut is defined radially by a leading edge face and a trailing edge face, which circumferentially define the transverse cut and are connected to each other by a bottom surface defining the transverse cut radially inward. The chamfer on the transverse cut can be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a planar surface inclined relative to the leading or trailing edge face, the planar surface continuing to the leading or trailing edge edge that defines the transverse cut circumferentially. A rounded chamfer is formed by a curved surface tangentially merged into its continuing leading or trailing edge face. The chamfer on the transverse cut is characterized by its height and width, which are respectively equal to the radial distance between a point common to the leading or trailing edge face that the chamfer continues and the leading or trailing edge edge that defines the transverse cut circumferentially, and the distance in a direction perpendicular to the leading or trailing edge face.

[0045] In a conventional manner, within the meaning of the 2019 European Tire and Rim Technology Organization (or "ETRTO") standard, the axial end of the tread is defined as the axial end of the tread surface of an unloaded tire mounted to a nominal rim and inflated to its nominal pressure, which is in contact with the ground on which the tire travels. Where there is a clear boundary between the tread surface and the remainder of the tire, the axial end of the tread can be easily determined. If the tread surface is continuous with the outer surface of the tire sidewall, each axial end of the tread passes through a point where the angle between the tangent to the tread surface and a straight line parallel to the axial direction passing through that point is equal to 30°. When there are multiple points in the meridional section plane where the absolute value of said angle is equal to 30°, the outermost radial point is used.

[0046] The tire according to the invention has a shape that is substantially annular about an axis of rotation (which substantially coincides with the axis of rotation of the tire). This axis of rotation defines three directions commonly used by those skilled in the art: the axial direction, the circumferential direction, and the radial direction.

[0047] The term "axial direction" refers to a direction that is substantially parallel to the axis of rotation of the tire (i.e., the axis of rotation of the tire).

[0048] The term "circumferential direction" refers to a direction that is substantially perpendicular to the axial direction and the tire radius (in other words, tangent to a circle centered on the tire's axis of rotation).

[0049] The term "radial direction" refers to the direction along the tire's radius, that is, any direction that intersects the tire's axis of rotation and is substantially perpendicular to that axis.

[0050] The term "center plane of the tire" (denoted as M) is understood to refer to a plane that is perpendicular to the tire's axis of rotation, located axially between the two tire bead sections, and passes through the axial center of the tire crown reinforcement.

[0051] The term "equatorial circumferential plane of the tire" (denoted as E) is understood to refer to a plane in the meridional section plane that passes through the tire's equator and is perpendicular to the midline and radial directions. The tire's equator is the axis in the meridional section plane (a plane perpendicular to the circumferential direction and parallel to the radial and axial directions), parallel to the tire's axis of rotation, and equidistant between the outermost radial point of the tread intended for contact with the ground and the innermost radial point of the tire intended for contact with a support (e.g., the rim) (the distance between these two points is equal to H).

[0052] The meridional plane is understood as a plane that is parallel to the axis of rotation of the tire, includes the axis of rotation of the tire, and is perpendicular to the circumferential direction.

[0053] "Radially inner" and "radially outer" are understood as "closer to the tire's axis of rotation" and "further away from the tire's axis of rotation," respectively. "Axially inner" and "axially outer" are understood as "closer to the tire's center plane" and "further away from the tire's center plane," respectively.

[0054] A tire bead is understood as a portion of the tire designed to attach the tire to a mounting support (such as a wheel including a rim). Therefore, each tire bead is specifically designed to contact the flange of the rim to which it is attached.

[0055] Any range of values ​​expressed as “between a and b” refers to a range of values ​​greater than a and less than b (i.e., excluding endpoints a and b), while any range of values ​​expressed as “from a to b” refers to a range of values ​​from a to b (i.e., including strict endpoints a and b).

[0056] In some preferred embodiments of the invention, the tire is intended for use in passenger vehicles as defined by the European Tire and Rim Technology Organization (ETRTO) standard of 2019. According to the ETRTO standard of 2019, such a tire has a cross-section in the meridional plane characterized in that the section height H and the nominal section width S satisfy a ratio H / S (expressed as a percentage) of at most 90, preferably at most 80, more preferably at most 70 and at least 30, preferably at least 40, and the nominal section width S is at least 115 mm, preferably at least 155 mm, more preferably at least 175 mm and at most 385 mm, preferably at most 315 mm, more preferably at most 285 mm, and even more preferably at most 255 mm. Furthermore, the diameter D at the rim flange (which defines the diameter of the rim on which the tire is mounted) is at least 12 inches, preferably at least 16 inches and at most 24 inches, preferably at most 20 inches.

[0057] In embodiments where the main circumferential cut is a relatively wide main circumferential groove (especially in the case of tires for passenger vehicles and multi-purpose vehicles) and has a very high risk of puncture (therefore the present invention is particularly advantageous), the axial width of the main circumferential cut or each main circumferential cut is greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, more preferably greater than or equal to 8.0 mm, and even more preferably ranging from 8.0 mm to 20.0 mm.

[0058] In embodiments where the main circumferential cuts are relatively deep (especially in the case of tires for passenger vehicles and multi-purpose vehicles) and have a very high risk of puncture (and thus the present invention is particularly advantageous), the depth of the main circumferential cuts or each main circumferential cut ranges from 4.0 mm to the tread height, preferably from 5.0 mm to the tread height, and more preferably from 5.5 mm to the tread height.

[0059] Advantageously, the self-sealing product layer has a significant axial width relative to the main circumferential cut, close to the main circumferential cut, in order to effectively seal any possible holes. Therefore, the self-sealing product layer includes at least one axial portion referred to as a thick axial portion, which at least partially coincides with all or part of an axial portion or each axial portion extending axially aligned with the main circumferential cut or each main circumferential cut. The thick axial portion or each thick axial portion is defined axially by two adjacent inflection points on the radially inner surface curve of the self-sealing product layer. The thickness of the thick axial portion increases from each of the inflection points in a direction axially toward the inside of the thick axial portion. The axial width Wx of the thick axial portion satisfies Wx / Lax ≥ 0.50, preferably Wx / Lax > 1.00, where Lax is the axial width of the main circumferential cut.

[0060] Therefore, as described above, the axial width of the thick axial portion can be smaller than the axial width of the main circumferential cut, but it is still sufficient to effectively seal any possible holes. In this case, the thick axial portion coincides with a portion of the axial portion of the self-sealing product layer that extends aligned with the main circumferential cut. Similarly, the axial width of the thick axial portion can preferably be greater than or equal to the axial width of the main circumferential cut. In this case, a portion of the thick axial portion coincides with the axial portion of the self-sealing product layer that extends aligned with the main circumferential cut.

[0061] An inflection point represents the point in the meridional section plane where the direction of curvature of the radial inner surface curve of the self-sealing product layer changes. It also represents the termination point of the radial inner surface curve of the self-sealing product layer in contact with the airtight layer. The axial width of the thick axial portion, or each thick axial portion, is, for example, the axial distance between two inflection points measured in the meridional section plane.

[0062] Advantageously, Wx / Lax ≤ 4.00, preferably Wx / Lax ≤ 3.00, more preferably Wx / Lax ≤ 2.00, even more preferably Wx / Lax ≤ 1.50, and very preferably Wx / Lax ≤ 1.25. To avoid excessively increasing tire weight, it is preferable not to provide excessively wide axial portions, unless it has been proven to be preferred for optimizing puncture resistance performance (especially at the tire shoulder). Therefore, the thick axial portion corresponding to the outermost main circumferential cut may not satisfy the above conditions, while other thick axial portions corresponding to other main circumferential cuts may satisfy the above conditions.

[0063] In some preferred embodiments, Ea ≥ 1.10 × Eb, preferably Ea ≥ 1.30 × Eb, and more preferably Ea ≥ 1.50 × Eb. For a given value of Ea, the larger the ratio Ea / Eb, the smaller the average thickness Eb of the axial portion extending axially aligned with the rib, and the greater the mass gain. For a given value of Eb, the larger the ratio Ea / Eb, the larger the average thickness Ea of the axial portion extending axially aligned with the main circumferential cut, which promotes the effectiveness of sealing any holes that may be present in the main circumferential cut.

[0064] In some embodiments, Ea ≤ 5.00 × Eb, preferably Ea ≤ 4.00 × Eb, and more preferably Ea ≤ 2.50 × Eb. For a given value of Ea, the smaller the ratio Ea / Eb, the greater the average thickness Eb of the axial portion extending axially aligned with the rib, and the better the effectiveness of sealing any possible holes in the rib, even if those holes are relatively small. For a given value of Eb, the smaller the ratio Ea / Eb, the greater the reduction in the average thickness Ea of the axial portion extending axially aligned with the main circumferential cut, which can mitigate the weight of the self-sealing product.

[0065] In the embodiment described above, which maximizes the trade-off between mass gain and the effectiveness of sealing possible holes in the main circumferential cut, Ea-Eb ≥ 0.5 mm, preferably Ea-Eb ≥ 1.0 mm.

[0066] In the tires for passenger vehicles and multi-purpose vehicles as described above, the average thickness Ea is advantageously in the range of 2.0 mm to 5.0 mm, preferably 2.5 mm to 4.5 mm, and the average thickness Eb is advantageously in the range of 0.5 mm to 4.0 mm, preferably 1.0 mm to 3.0 mm.

[0067] Advantageously, the rib-like portion, or each rib-like portion, is defined axially by an inner axial end and an outer axial end, each selected from:

[0068] - The axial end of the tread, and

[0069] - The inner or outer end of the axial circumferential cut

[0070] The inner and outer ends of the rib-shaped portion are adjacent to each other.

[0071] When a rib is axially defined by the axial end of the tread and the axially inner or outer end of the main circumferential cut, the side rib is usually referred to because it is located on the side portion of the tread. When a rib is axially defined by the axially inner or outer end of the main circumferential cut and the adjacent axially outer or inner end of another main circumferential cut, the central rib is usually referred to because it is located in the central portion of the tread.

[0072] The fact that the ribs of the tread, or each rib, are described as a central rib does not restrict their positioning relative to the center plane of the tire.

[0073] The term "adjacent ends" is understood to mean that the axial inner end or axial outer end without a main circumferential cut is arranged axially between the adjacent ends.

[0074] In embodiments where the tread includes multiple axially defined main circumferential cuts that define one or more central ribs, it is advantageous that the thickness of the self-sealing product layer varies between a relatively large average thickness (when aligned with the main circumferential cuts) and a relatively small average thickness (when aligned with the ribs). Therefore, the tread includes:

[0075] -N>1 main circumferential cuts, wherein the depth Hai of each main circumferential cut satisfies Hai / Hs≥50%, preferably Hai / Hs≥75%, more preferably Hai / Hs≥90%, and i ranges from 1 to N, where N is the total number of main circumferential cuts on the tire.

[0076] -Q = N-1 ≥ 1 central rib, wherein each central rib is axially arranged between two adjacent main circumferential cuts and is defined axially by the two adjacent main circumferential cuts, and Q is the total number of central ribs present on the tire.

[0077] The self-sealing product layer includes:

[0078] -N>1 axial portions, each of which extends axially aligned with one of the N main circumferential cuts, and each has an average thickness Eai>0 for the self-sealing product.

[0079] - Q = N - 1 ≥ 1 axial parts, each of the axial parts extending axially in alignment with one of the Q central rib portions or the Q central rib portions, and each having an average thickness Ebj of the self-sealing product ≥ 0 (where j ranges from 1 to Q), and being arranged axially between two adjacent axial parts that extend axially in alignment with two of the N main circumferential cuts in the self-sealing product layer, and such that for each value of i ranging from 1 to N, at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, more preferably 100% of the values of j ranging from 1 to Q satisfy Ebj < Eai.

[0080] In this embodiment, in one variant, Ea1 = Ea2 = … EaN and Eb1 = Eb2 = … EbQ, so for each value of i ranging from 1 to N and for 100% of the values of j ranging from 1 to Q, the relation Ebj < Eai is satisfied. In other variants, depending on the trade-off between the desired effectiveness and quality gain of the self-sealing product layer, some values of Eai can be different from other values, and when it is desired to maximize the quality gain, for each value of i and for at least 50% of the values of j, preferably for 100% of the values of j, the relation Ebj < Eai can be satisfied. Similarly, for the same reason, some values of Ebj can be different from other values.

[0081] "Adjacent main circumferential cuts" is understood to mean that no main circumferential cut is arranged axially between the adjacent main circumferential cuts. Similarly, "adjacent axial parts that extend axially in alignment with two of the N main circumferential cuts" is understood to mean that no axial part that extends axially in alignment with one of the N main circumferential cuts is arranged axially between the adjacent axial parts.

[0082] In certain embodiments as shown above that can promote quality gain and the sealing effectiveness of possible holes in the main circumferential cuts, for each value of i ranging from 1 to N, at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, more preferably 100% of the values of j ranging from 1 to Q satisfy Eai ≥ 1.10 × Ebj, preferably Eai ≥ 1.30 × Ebj, more preferably Eai ≥ 1.50 × Ebj.

[0083] In other embodiments as shown above that can promote quality gain and the sealing effectiveness of possible holes in the rib portions, for each value of i ranging from 1 to N, at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, more preferably 100% of the values of j ranging from 1 to Q satisfy Eai ≤ 5.00 × Ebj, preferably Eai ≤ 4.00 × Ebj, more preferably Eai ≤ 2.50 × Ebj.

[0084] In the embodiment described above, which maximizes the trade-off between mass gain and sealing effectiveness of possible holes in the main circumferential cut, for each value of i ranging from 1 to N, at least 50% of the value of j ranging from 1 to Q, preferably at least 75% of the value of j ranging from 1 to Q, more preferably 100% of the value of j ranging from 1 to Q, satisfy Eai-Ebj ≥ 0.5 mm, and preferably Eai-Ebj ≥ 1.0 mm.

[0085] As shown above, in the tires for passenger vehicles and multi-purpose vehicles described above, the range of each average thickness Eai is advantageously from 2.0 mm to 5.0 mm, preferably from 2.5 mm to 4.5 mm, and the range of each average thickness Ebj is advantageously from 0.5 mm to 4.0 mm, preferably from 1.0 mm to 3.0 mm.

[0086] In most tires used in passenger vehicles and multi-purpose vehicles, N = 2, 3, or 4.

[0087] To reduce the risk of perforation of the central rib or each central rib, and thus mitigate the quality of self-sealing products aligned with the central rib or each central rib, the central rib or each central rib either does not include a transverse cut or includes a transverse cut. For at least 50%, preferably at least 75%, more preferably 100% of the number of transverse cuts in the central rib or each central rib, each transverse cut satisfies at least one of the following conditions:

[0088] - The width of the transverse incision in the central rib is strictly less than 1.6 mm, preferably strictly less than 1.0 mm, and more preferably strictly less than 0.7 mm.

[0089] - The depth H of the transverse incision in the central rib satisfies H / Hs<50%, preferably H / Hs≤30%.

[0090] In some implementations, the tread includes:

[0091] - An axial central portion, comprising N main circumferential incisions and Q central ribs, the axial central portion being defined axially by the outermost axially extending ends of each of the outermost axial main circumferential incisions.

[0092] - A first axial side portion and a second axial side portion, the first axial side portion and the second axial side portion being arranged axially outside the axial central portion, and one of each being arranged axially on each side of the axial central portion relative to the center plane of the tire, the first axial side portion and the second axial side portion respectively extending axially from each axial end of the tread to each axial outer end of each axial main circumferential cutout.

[0093] The first axial side portion and the second axial side portion each respectively include a first side rib portion and a second side rib portion, and at least one of the first side rib portion and the second side rib portion includes at least one transverse incision, the transverse incision having a depth Ht satisfying Ht / Hs≥50%, preferably Ht / Hs≥75%.

[0094] The self-sealing product layer includes at least one axial portion extending axially and aligned with the first side rib portion or the second side rib portion, the first side rib portion or the second side rib portion includes at least one transverse incision, the transverse incision having a depth Ht satisfying Ht / Hs≥50%, preferably Ht / Hs≥75%, and having an average thickness Ec of the self-sealing product>0, such that at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, more preferably 100% of the values of j ranging from 1 to Q satisfy Ebj<Ec.

[0095] In these embodiments, in addition to the main circumferential incision and the central rib portion, the tire further includes other axial portions (in this case the first side rib portion and the second side rib portion), and due to the presence of relatively deep transverse incisions formed in the side rib portions, these other axial portions have a risk of perforation. To ensure the effectiveness of preventing perforation in these first side rib portions and second side rib portions, the above embodiments provide the presence of an axial portion of the self-sealing product layer aligned with at least one of the first side rib portion and the second side rib portion.

[0096] In these embodiments, in one variant, Eb1 = Eb2 = … EbQ, so that for 100% of the values of j ranging from 1 to Q, the relationship Ebj<Ec is satisfied. In other variants, depending on the compromise between the desired effectiveness and the quality gain of the self-sealing product layer, some values of Ebj can be different from other values, and when it is desired to maximize the quality gain, for at least 50% of the values of j, preferably at least 75% of the values of j, more preferably 100% of the values of j, the relationship Ebj<Ec can be satisfied.

[0097] In certain embodiments as shown above that can promote quality gain and the sealing effectiveness of possible holes in the side rib portions, at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, more preferably 100% of the values of j ranging from 1 to Q satisfy Ec≥1.10×Ebj, preferably Ec≥1.30×Ebj, more preferably Ec≥1.50×Ebj.

[0098] In other embodiments such as those shown above that can promote mass gain and the sealing effectiveness of possible holes in each central rib, at least 50% of the values of j in the range from 1 to Q, preferably at least 75% of the values of j in the range from 1 to Q, more preferably 100% of the values of j in the range from 1 to Q satisfy Ec ≤ 5.00 × Ebj, preferably Ec ≤ 4.00 × Ebj, more preferably Ec ≤ 2.50 × Ebj.

[0099] In embodiments such as those described above that can maximize the compromise between mass gain and the sealing effectiveness of possible holes in the side ribs, at least 50% of the values of j in the range from 1 to Q, preferably at least 75% of the values of j in the range from 1 to Q, more preferably 100% of the values of j in the range from 1 to Q satisfy Ec - Ebj ≥ 0.5 mm, preferably Ec - Ebj ≥ 1.0 mm.

[0100] Preferably, each of the first side rib and the second side rib includes at least one transverse incision having a depth Ht such that Ht / Hs ≥ 50%, preferably Ht / Hs ≥ 75%.

[0101] The self-sealing product layer includes a first axial portion and a second axial portion that extend axially aligned with the first side rib and the second side rib respectively, and have average thicknesses Ec1 and Ec2 of the self-sealing product respectively, where Ec1 > 0 and Ec2 > 0, and at least 50% of the values of j in the range from 1 to Q, preferably at least 75% of the values of j in the range from 1 to Q, more preferably 100% of the values of j in the range from 1 to Q satisfy Ebj < Ec1 and Ebj < Ec2.

[0102] In certain embodiments such as those shown above that can promote mass gain and the sealing effectiveness of possible holes in each side rib, at least 50% of the values of j in the range from 1 to Q, preferably at least 75% of the values of j in the range from 1 to Q, more preferably 100% of the values of j in the range from 1 to Q satisfy Ec1 ≥ 1.10 × Ebj and Ec2 ≥ 1.10 × Ebj, preferably Ec1 ≥ 1.30 × Ebj and Ec2 ≥ 1.30 × Ebj, more preferably Ec1 ≥ 1.50 × Ebj and Ec2 ≥ 1.50 × Ebj.

[0103] In other embodiments shown above that can promote quality gain and sealing effectiveness of possible holes in each central rib, at least 50% of the value of j ranging from 1 to Q, preferably at least 75% of the value of j ranging from 1 to Q, more preferably 100% of the value of j ranging from 1 to Q, satisfy Ec1≤5.00×Ebj and Ec2≤5.00×Ebj, preferably Ec1≤4.00×Ebj and Ec2≤4.00×Ebj, more preferably Ec1≤2.50×Ebj and Ec2≤2.50×Ebj.

[0104] In the embodiment described above, which maximizes the trade-off between mass gain and sealing effectiveness of possible holes in each side rib, at least 50% of the value of j in the range of 1 to Q, preferably at least 75% of the value of j in the range of 1 to Q, more preferably 100% of the value of j in the range of 1 to Q, satisfies Ec1-Ebj≥0.5mm and Ec2-Ebj≥0.5mm, and preferably Ec1-Ebj≥1.0mm and Ec2-Ebj≥1.0mm.

[0105] Advantageously, the self-sealing product layer has a significant axial width relative to the axial width of the side ribs near the side ribs, so as to effectively seal any possible holes. Therefore, the self-sealing product layer includes at least one axial portion referred to as a thick axial portion, the thick axial portion or each thick axial portion at least partially coinciding with all or part of an axial portion or each axial portion extending axially aligned with at least one of the first and second side ribs. The thick axial portion or each thick axial portion is defined axially by two adjacent inflection points on the radial inner surface curve of the self-sealing product layer. The thickness of the thick axial portion increases from each inflection point in a direction axially toward the inside of the thick axial portion. The axial width Wy of the thick axial portion satisfies Wy / Lcy ≥ 0.50, preferably Wy / Lcy > 1.00, where Lcy is the axial width of the side ribs.

[0106] Therefore, as described above, the axial width of the thick axial portion can be less than the axial width of one or each of the first and second side ribs, but it is still sufficient to effectively seal any possible holes. In this case, a portion of the thick axial portion coincides with a portion of the axial portion of the self-sealing product layer that extends in alignment with one or each of the first and second side ribs. Similarly, the axial width of the thick axial portion can preferably be greater than or equal to the axial width of one or each of the first and second side ribs. In this case, a portion of the thick axial portion coincides with a portion of the axial portion of the self-sealing product layer that extends in alignment with one or each of the first and second side ribs.

[0107] In embodiments where the lateral cuts are relatively wide lateral grooves (especially in the case of tires for passenger vehicles and multi-purpose vehicles) and have a very high risk of puncture (therefore the present invention is particularly advantageous), the width of the lateral cuts or each lateral cut is greater than or equal to 0.7 mm, preferably greater than or equal to 1.0 mm, and more preferably greater than or equal to 1.6 mm.

[0108] In embodiments where the lateral cuts are relatively deep (especially in the case of tires for passenger vehicles and multi-purpose vehicles) and have a very high risk of puncture (and thus the present invention is particularly advantageous), the depth of the lateral cuts or each lateral cut ranges from 2.0 mm to the tread height, preferably from 4.0 mm to the tread height, and more preferably from 5.0 mm to the tread height.

[0109] To maximize the effectiveness of the self-sealing product layer over most of the axial width of the tread, each axial end of the self-sealing product layer is arranged at a distance less than or equal to 20% of the axial width of the tread, preferably less than or equal to 10%, and preferably axially inside each axial end of the tread.

[0110] In a conventional manner, a tire includes a crown, two sidewalls, and two beads, with each sidewall connecting each bead to the crown. Still in a conventional manner, the crown includes a tread and a crown reinforcement arranged radially inside the tread. The tire also includes a carcass reinforcement anchored in each bead and extending radially in each sidewall and axially in the crown, located radially inside the crown reinforcement.

[0111] In a conventional manner, a tread reinforcement includes at least one tread layer, which comprises reinforcing elements. These reinforcing elements are preferably fabric filament elements or metal filament elements.

[0112] In embodiments that achieve the performance of a tire as defined by ETRTO, referred to as a radial tire, the carcass reinforcement includes at least one carcass layer, and each carcass layer or each carcass layer includes a carcass filament reinforcement element, each carcass filament reinforcement element extending substantially along a principal direction that forms an angle with the circumferential direction of the tire ranging from 80° to 90° in absolute value. Attached Figure Description

[0113] The invention will be better understood by reading the following description, which is given by way of non-limiting embodiments only and with reference to the accompanying drawings, in which:

[0114] - Figure 1 This is a view of the tire according to the first embodiment of the present invention in a meridional section plane parallel to the tire's axis of rotation.

[0115] - Figure 2 for Figure 1 A top view of the tire tread.

[0116] - Figure 3 The view shown is in a meridional section plane parallel to the tire's axis of rotation. Figure 1 The tire manufacturing method, and

[0117] - Figure 4 To and Figure 1 A view of a tire similar to that of the tire according to a second embodiment of the present invention. Detailed Implementation

[0118] The accompanying drawings related to the tire show reference frames X, Y, and Z corresponding to the tire's usual axial (Y), radial (Z), and circumferential (X) directions, respectively.

[0119] In the following description, measurements are taken on an unloaded and uninflated tire, or on a section of the tire in the meridional plane.

[0120] Figure 1 A tire according to the invention, indicated by reference numeral 10, is shown. The tire 10 has a substantially annular shape about an axis of rotation substantially parallel to the axial direction Y. The tire 10 is intended for use in passenger vehicles and is sized 245 / 45R18. In the various figures, the tire 10 is depicted as brand new, i.e., before it has been driven.

[0121] Tire 10 includes a crown 12, which includes a tread 14 and a crown reinforcement 16. The tread 14 is intended to contact the ground when the tire is in motion, and the crown reinforcement 16 extends in the crown 12 in the circumferential direction X. Tire 10 also includes a ply 18, which is hermetically sealed relative to inflation gas and is intended to define a closed cavity with the mounting support of tire 10 after tire 10 is mounted to a mounting support (e.g., a rim).

[0122] The crown reinforcement 16 includes a working reinforcement 20 and a ring reinforcement 22. The working reinforcement 16 includes at least one working layer, and in this case, two working layers, including a radially inner working layer 24 arranged radially inside the radially outer working layer 26.

[0123] The hoop reinforcement 22 includes at least one hoop layer, in this case including a hoop layer 28.

[0124] The crown reinforcement 16 is radially covered by the tread 14. In this case, the ring reinforcement 22 (in this case, the ring layer 28) is arranged radially outside the working reinforcement 20 and is therefore radially positioned between the working reinforcement 20 and the tread 14.

[0125] The tire 10 includes two sidewalls 30, each extending radially inward to a crown 12. The tire 10 also has two beads 32, located radially inside the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown 12.

[0126] Tire 10 includes a carcass reinforcement 34 anchored in each bead 32, and in this case, the carcass reinforcement 34 is wound around a bead line 33. The carcass reinforcement 34 extends radially in each sidewall 30 and axially in the crown 12, and is located radially inside a crown reinforcement 16. The crown reinforcement 16 is radially disposed between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 includes at least one carcass layer 36.

[0127] Each working layer 24, 26, ring layer 28, and carcass layer 36 includes an elastomer matrix in which one or more filamentary reinforcing elements corresponding to the layer are embedded.

[0128] The hoop reinforcement 22 (in this case, the hoop layer 28) includes one or more hoop filamentary reinforcement elements that are spirally wound circumferentially in a principal direction, forming an angle AF with the circumferential direction X of the tire 10. The absolute value of the angle AF is less than or equal to 10°, preferably less than or equal to 7°, and more preferably less than or equal to 5°. In this case, AF = -5°.

[0129] The radial inner working layer 24 and the radial outer working layer 26 each include a working filament reinforcing element extending in a principal direction. This principal direction forms opposite-oriented angles AT1 and AT2 with the circumferential direction X of the tire 10, respectively. The absolute values ​​of these angles AT1 and AT2 are strictly greater than 10°, preferably ranging from 15° to 50°, and more preferably from 15° to 30°. In this case, AT1 = -26° and AT2 = +26°.

[0130] The carcass layer 36 includes carcass filamentary reinforcing elements that extend in a principal direction D3, which forms an angle AC with the circumferential direction X of the tire 10. The absolute value of the angle AC is greater than or equal to 60°, preferably in the range of 80° to 90°, and in this case AC = +90°.

[0131] Each hoop-shaped filamentary reinforcing element typically comprises two multifilament strands, each made of a yarn spun from an aliphatic polyamide (in this case, nylon) monofilament with a count of 140 tex. These two multifilament strands are individually helically twisted at 250 turns / meter in one direction and then helically twisted together at 250 turns / meter in the opposite direction. The two multifilament strands are spirally wound around each other. As a variation, a hoop-shaped filamentary reinforcing element may be used comprising a multifilament strand made of a yarn spun from an aliphatic polyamide (in this case, nylon) monofilament with a count of 140 tex and a multifilament strand made of an aramid (in this case, aramid) monofilament with a count of 167 tex. These two multifilament strands are individually helically twisted at 290 turns / meter in one direction and then helically twisted together at 290 turns / meter in the opposite direction. The two multifilament strands are spirally wound around each other. This variant will give AT1 = -29° and AT2 = +29°.

[0132] Each working filamentary reinforcing element is an assembly of two steel monofilaments spirally wound with a 14 mm twist pitch, each monofilament having a diameter of 0.30 mm. As a variant, an assembly of six steel monofilaments with a diameter of 0.23 mm can also be used, comprising an inner layer of two monofilaments spirally wound together with a 12.5 mm twist pitch in a first direction (e.g., the Z direction), and an outer layer of four monofilaments spirally wound together with a 12.5 mm twist pitch in a second direction opposite to the first direction (e.g., the S direction). In another variant, each working filamentary reinforcing element consists of a single steel monofilament with a diameter of 0.30 mm. More typically, the diameter of the steel monofilament ranges from 0.25 mm to 0.32 mm.

[0133] Each carcass filamentary reinforcing element typically comprises two multifilament strands, each made of spun yarn from polyester (PET in this case) monofilaments. These two multifilament strands are individually helically twisted in one direction at 240 turns / meter, and then helically twisted together in the opposite direction at 240 turns / meter. Each of these multifilament strands has a yarn count of 220 tex. In other variations, a yarn count of 144 tex and a twist of 420 turns / meter can be used, or a yarn count of 334 tex and a twist of 270 turns / meter can be used.

[0134] refer to Figure 1 and Figure 2The tread 14 includes a tread surface 38 through which the tread 14 contacts the ground. The tread surface 38 is designed to contact the ground when the tire 10 is traveling on the ground. The tread is axially defined by a first axial edge 41 and a second axial edge 42 passing through each point N arranged on both sides of the central plane M, and the angle between the tangent T of the tread surface 38 and the straight line R parallel to the axial direction Y and passing through that point is equal to 30°.

[0135] The tread 14 includes an axial central portion P0, a first axial side portion P1, and a second axial side portion P2. The first axial side portion P1 and the second axial side portion P2 are arranged axially on the outside of the axial central portion P0, and one is arranged axially on each side of the axial central portion P0 relative to the center plane M of the tire 10.

[0136] Without specifying the embodiment shown, the axial width L0 of the central portion P0 is greater than or equal to 50% of the axial width L of the tread surface 38 of the tire 10 when it is brand new, preferably greater than or equal to 60% and less than or equal to 80%, and more preferably less than or equal to 70%. The axial widths L1 and L2 of the first axial side portion P1 and the second axial side portion P2 are each less than or equal to 25% of the axial width L of the tread surface 38 of the tire 10 when it is brand new, preferably less than or equal to 20% and greater than or equal to 5%, and more preferably greater than or equal to 10%. The ratio of the axial width L0 of the central portion P0 to the axial widths L1 and L2 of the first axial side portion P1 and the second axial side portion P2 is greater than or equal to 3.0, preferably in the range of 3.0 to 5.0, and more preferably in the range of 4.0 to 4.5.

[0137] The axial central portion P0 includes N>1 main circumferential cuts (in this case, N main circumferential grooves), which include the first, second, third, and fourth main circumferential cuts, respectively indicated by reference numerals 52, 54, 56, and 58. The first main circumferential cut 52 and the second main circumferential cut 54 are arranged axially on both sides of the central plane M of the tire 10, and are the outermost axial main circumferential cuts of the tread 14.

[0138] Each primary circumferential cut 52 to 58 is defined axially by an outer axial end, indicated by reference numerals 521, 541, 561, and 581, respectively, and an inner axial end, indicated by reference numerals 522, 542, 562, and 582, respectively. An axial central portion P0 extends axially from the outer axial end 521 of the first primary circumferential cut 52 to the outer axial end 541 of the second primary circumferential cut 54.

[0139] Each of the main circumferential cuts 52 to 58 has a depth represented by reference numerals Ha1, Ha2, Ha3, and Ha4, respectively, and the depth ranges from 4.0 mm to the tread height Hs, preferably from 5.0 mm to the tread height Hs, and more preferably from 5.5 mm to the tread height Hs. Each depth Ha1, Ha, Ha3, and Ha4 is greater than or equal to 50% of the tread height Hs. In this case, Hs = Ha3 = Ha4 = 6.5 mm and Ha1 = Ha2 = 6.0 mm. Therefore, each main circumferential cut 52, 54, 56, and 58 satisfies Hai / Hs ≥ 75%, and in this case, Hai / Hs ≥ 90%, where i ranges from 1 to 4 because Hs = 6.5 mm.

[0140] Each main circumferential cut 52 to 58 has an axial width, respectively indicated by reference numerals La1, La2, La3, and La4, and the axial width is greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, more preferably greater than or equal to 8.0 mm, and even more preferably 8.0 mm to 20.0 mm. In this case, La1 = La2 = 10.0 mm and La3 = La4 = 12.5 mm.

[0141] The axial central portion P0 includes Q = N-1 ≥ 1 central rib, which in this case are the first, second, and third central ribs, respectively, indicated by reference numerals 62, 64, and 66. Each central rib 62, 64, and 66 is arranged axially between two adjacent main circumferential cuts 52 to 58 and is defined axially by the two adjacent main circumferential cuts 52 to 58.

[0142] Each central rib 62, 64, 66 is defined axially by an inner axial end and an outer axial end, each of which is either the inner or outer axial end of a main circumferential cut 52 to 58. The inner and outer axial ends of each central rib 62, 64, 66 are adjacent to each other. In this particular case, the first central rib 62 is defined axially by the inner axial end 522 of the first main circumferential cut 52 and the outer axial end 561 of the third main circumferential cut 56. The second central rib 64 is defined axially by the inner axial end 562 of the third main circumferential cut 56 and the inner axial end 582 of the fourth main circumferential cut 58. The third central rib 66 is defined axially by the outer axial end 581 of the fourth main circumferential cut 58 and the inner axial end 542 of the second main circumferential cut 54.

[0143] The axial central portion P0 includes additional circumferential cuts formed on the central ribs 62, 64, and 66. In this case, each central rib 62, 64, and 66 includes additional circumferential cuts 71, 72, and 73, respectively. The depth of each additional circumferential cut 71, 72, and 73 is strictly less than 50% of the tread height Hs, preferably less than or equal to 30% of the tread height Hs, more preferably ranging from 10% to 30% of the tread height Hs, in this case ranging from 1.0 mm to 4.0 mm, and in this case equal to 2.0 mm. The axial width of each additional circumferential cut 71, 72, and 73 ranges from 4% to 15% of the respective axial width of each central rib 62, 64, and 66, preferably from 4% to 10%, in this case less than or equal to 3.0 mm, preferably ranging from 1.0 mm to 3.0 mm, and in this case equal to 1.0 mm.

[0144] Furthermore, each central rib 62, 64, 66 includes transverse cuts 74, 75, 76, and for at least 50%, preferably at least 75%, more preferably 100% of the number of transverse cuts 74, 75, 76 in each central rib 62, 64, 66, the transverse cuts 74, 75, 76 satisfy at least one of the following conditions:

[0145] - The width of the transverse incision in the central rib is strictly less than 1.6 mm, preferably strictly less than 1.0 mm, and more preferably strictly less than 0.7 mm.

[0146] - The depth H of the transverse incision in the central rib satisfies H / Hs<50%, preferably H / Hs≤30%.

[0147] In this specific case, each central rib 62, 64, 66 includes transverse incisions 74, 75, 76, and 100% of the transverse incisions 74, 75, 76 of each central rib 62, 64, 66 satisfy the condition that the width of each transverse incision 74, 75, 76 is strictly less than 0.7 mm. In this respect, each central rib 62, 64, 66 is referred to as having a shallow incision.

[0148] The first axial portion P1 extends axially from the first axial end 41 of the tread 14 to the axial outer end 521 of the first main circumferential cut 52. The second axial portion P2 extends axially from the second axial end 42 of the tread 14 to the axial outer end 541 of the second main circumferential cut 54.

[0149] The first axial side portion P1 and the second axial side portion P2 each include a first side rib and a second side rib, respectively indicated by reference numerals 68 and 70, and in this case, each is composed of a first side rib 68 and a second side rib 70. Therefore, the tire 10 includes P = 2 > 1 side ribs. Thus, the first side rib 68 is axially defined by two adjacent ends (in this case, the axial end 41 of the tread 14 and the axially outer end 521 of the first main circumferential cutout 52). The second side rib 70 is axially defined by two adjacent ends (in this case, the axial end 42 of the tread 14 and the axially outer end 541 of the second main circumferential cutout 54). The first side rib 68 and the second side rib 70 each have an axial width indicated by reference numerals Lc1 and Lc2, respectively, where Lc1 = Lc2 = 33 mm still holds true here.

[0150] The first side rib 68 and the second side rib 70 each include transverse cuts 77 and 78, the depths Ht of which satisfy Ht / Hs≥50%, preferably Ht / Hs≥75%, and more preferably Ht / Hs≥90%. The depth Ht of each transverse cut 77 and 78 ranges from 2.0 mm to the tread height Hs, preferably from 4.0 mm to the tread height Hs, and even more preferably from 5.0 mm to the tread height Hs, in which case Ht = 6.0 mm. The width of each transverse cut 77 and 78 is greater than or equal to 0.7 mm, preferably greater than or equal to 1.0 mm, and more preferably greater than or equal to 1.6 mm. In this respect, each side rib 68 and 70 is referred to as having a relatively deep cut.

[0151] refer to Figure 1 The tire 10 also includes a self-sealing product layer 80, which extends circumferentially inside a portion of the airtight inner layer 18 and is at least partially aligned with the tread 14. Self-sealing products are known in the prior art and can be particularly selected from those described in documents WO2020009849, WO2011092122, and WO2011092123. The self-sealing product layer is axially defined by two axial ends 81, 82, which are arranged relative to each axial end 41, 42 of the tread 14 at an axial distance less than or equal to 20%, preferably less than or equal to 10%, of the axial width of the tread. In this case, each axial end 81, 82 is radially aligned with each end 41, 42, although a preferred embodiment is one in which each axial end 81, 82 is arranged axially inside each axial end 81, 82.

[0152] The self-sealing product layer 80 includes axial portions of L ≥ 1 (in this case L = 4 > 1) referred to as thick axial portions (in this case indicated by reference numerals 90, 92, 94, 96) and M ≥ 1 (in this case M = 3 > 1) referred to as thin axial portions (in this case indicated by reference numerals 100, 102, 104). Figure 1 As shown, each thick axial portion and each thin axial portion are defined by two inflection points 81, 82, 83, 84, 85, 86, 87, and 88 on the radial inner surface curve 89 of the self-sealing product layer 80. Each thick axial portion 90 to 96 is defined axially by two adjacent inflection points such that the thickness of each thick axial portion 90 to 96 increases from each inflection point in a direction axially toward the inside of each thick axial portion. Each thin axial portion 100 to 104 is defined axially by two adjacent inflection points such that the thickness of each thin axial portion 100 to 104 decreases from each inflection point in a direction axially toward the inside of the thin axial portion.

[0153] Each thick axial portion 90 to 96 and each thin axial portion 100 to 104 extends circumferentially continuously for at least 50%, preferably at least 75%, and more preferably at least 95% of the circumferential length of the self-sealing product layer 80, in which case it is 100% circumferentially continuous. The average thicknesses EE1, EE2, EE3, EE4 of each thick axial portion 90, 92, 94, 96 and the average thicknesses EM1, EM2, EM3 of each thin axial portion 100, 102, 104 extend circumferentially continuously for at least 50%, preferably at least 75%, and more preferably at least 95% of the circumferential length of the self-sealing product layer 80, in which case it is 100% substantially constant circumferentially. In this case, EE1 = EE2 = EE3 = EE4 = 3.45 mm and EM1 = EM2 = EM3 = 1.95 mm. Each thick axial portion 90, 92, 94, 96 includes axial portions 90', 92', 94', 96' extending axially aligned with each major circumferential cutout 52, 54, 56, 58, respectively. Therefore, the self-sealing product layer 80 includes N = 4 axial portions 90' to 96' extending axially and aligned with one of the N main circumferential cutouts 52 to 58. Each axial portion 90' to 96' has an average thickness Eai > 0 for the self-sealing product, where i ranges from 1 to 4. In this case, Ea1 = Ea2 = Ea3 = Ea4 = 3.50 mm.

[0154] Each thick axial portion 90, 92 further includes axial portions 90” and 92” extending axially aligned with the first side rib 68 and the second side rib 70, respectively. Each portion 90” and 92” has an average thickness Ec1>0 and Ec2>0, respectively. In this case, Ec1=Ec2=3.50mm.

[0155] Each thin axial portion 100, 102, 104 respectively includes axial portions 100', 102', 104' that respectively extend axially and are aligned with each of the central rib portions 62, 64, 66. Thus, the self-sealing product layer 80 includes Q = N - 1 = 3 axial portions 100', 102', 104' that extend axially and are aligned with one of the Q central rib portions 62, 64, 66. Each axial portion 100', 102', 104' is axially arranged between two adjacent axial portions 90' to 96'. Each axial portion 100', 102', 104' has an average thickness Ebj of the self-sealing product ≥ 0, where j ranges from 1 to 3. In this case, Eb1 = Eb2 = Eb3 = 2.00 mm.

[0156] It should be noted that for each value of i ranging from 1 to N, at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, and in this case 100% of the values of j ranging from 1 to Q satisfy Ebj < Eai, Ebj < Ec1, and Ebj < Ec2.

[0157] It should also be noted that for each value of i ranging from 1 to N, at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, and in this case 100% of the values of j ranging from 1 to Q on the one hand satisfy Eai ≥ 1.10 × Ebj, preferably Eai ≥ 1.30 × Ebj, more preferably Eai ≥ 1.50 × Ebj, and on the other hand satisfy Eai ≤ 5.00 × Ebj, preferably Eai ≤ 4.00 × Ebj, more preferably Eai ≤ 2.50 × Ebj. In this case, for each value of i ranging from 1 to N, 100% of the values of j ranging from 1 to Q satisfy Eai / Ebj = 1.75.

[0158] It should also be noted that at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, and in this case 100% of the values of j ranging from 1 to Q on the one hand satisfy Ec1 ≥ 1.10 × Ebj and Ec2 ≥ 1.10 × Ebj, preferably Ec1 ≥ 1.30 × Ebj and Ec2 ≥ 1.30 × Ebj, more preferably Ec1 ≥ 1.50 × Ebj and Ec2 ≥ 1.50 × Ebj, and on the other hand satisfy Ec1 ≤ 5.00 × Ebj and Ec2 ≤ 5.00 × Ebj, preferably Ec1 ≤ 4.00 × Ebj and Ec2 ≤ 4.00 × Ebj, more preferably Ec1 ≤ 2.50 × Ebj and Ec2 ≤ 2.50 × Ebj. In this case, 100% of the values of j ranging from 1 to Q satisfy Ec1 / Ebj = 1.75 and Ec2 / Ebj = 1.75.

[0159] Each thick axial portion 90, 92, 94, 96 coincides at least partially with all or part of each axial portion 90', 92', 94', 96'. In this case, as Figure 1 As shown, the axial width of each thick axial portion 90, 92, 94, 96 is greater than or equal to the axial width of each main circumferential cut 52, 54, 56, 58, respectively. Therefore, the axial widths W3 and W4 of each thick axial portion 94, 96 satisfy W3 / La3≤4.00 and W4 / La4≤4.00, preferably W3 / La3≤3.00 and W4 / La4≤3.00, more preferably W3 / La3≤2.00 and W2 / La2≤2.00, even more preferably W3 / La3≤1.50 and W4 / La4≤1.50, and most preferably W3 / La3≤1.25 and W4 / La4≤1.25. In this case, W3=W4=13.5mm, such that W3 / La3=W4 / La4=1.08.

[0160] Furthermore, each thick axial portion 90, 92 at least partially coincides with all or part of each axial portion 90”, 92”. In this case, as Figure 1 As shown, the axial width of each thick axial portion 90, 92 is greater than or equal to the axial width of each main circumferential cut 90”, 92”. Therefore, the axial widths W1 and W2 of each thick axial portion 90, 92 satisfy W1 / Lc1≥0.50 and W2 / Lc2≥0.50, preferably W1 / Lc1>1.00 and W2 / Lc2>1.00. In this case, W1=W2=44mm, such that W1 / Lc1=W2 / Lc2=1.33.

[0161] Furthermore, the conditions W1 / La1≥0.50 and W2 / La2≥0.50 are also true, preferably W1 / La1>1.00 and W2 / La2>1.00, and in this case W1 / La1=W2 / La2=4.40.

[0162] All conditions satisfied by the various axial portions 90 to 96, 90' to 96', 90”, 92”, 100 to 104 and 100’ to 104’ are satisfied at least 50, preferably at least 75%, more preferably at least 95%, and in the present case 100% of the circumferential length of the self-sealing product layer 80.

[0163] Each axial portion 90' to 96', 90", 92" and 100' to 104' of the self-sealing product layer extending in alignment with each cutout 52 to 58 and each rib 62 to 70 is at least 50%, preferably at least 75%, more preferably at least 95% of the circumferential length of the self-sealing product layer 80, and in this case, extends 100% continuously in the circumferential direction.

[0164] The average thicknesses Ea1 to Ea4, Ec1, Ec2 and Eb1 to Eb3 of each axial portion 90' to 96', 90", 92" and 100' to 104' are at least 50%, preferably at least 75%, more preferably at least 95% of the circumferential length of the self-sealing product layer 80, in which case they are substantially constant along the circumferential direction for 100%.

[0165] Reference Figure 3 A method for manufacturing tire 10 is described.

[0166] Provide brand new tires that are in a vulcanized state and do not have a self-sealing product layer 80.

[0167] Extrusion apparatus and devices are provided for applying strips 200 of a self-sealing product with a width of 15 mm and a thickness of 0.9 mm. These devices are specifically described in WO2015 / 173120. In variations, tire beads of the self-sealing product may be used.

[0168] The self-sealing strip 200 is wound in multiple circumferential turns, in this case 33 turns, around the radially inner side of the tire's airtight layer 18. This winding step is performed according to the principle of winding the strip 200 into circumferential loops, and the result is shown in... Figure 3 middle.

[0169] The winding of strip 200 begins at axial end 81 and stops when it reaches axial end 82. Strip 200 is wound between the two axial ends 81 and 82 without interruption.

[0170] In the winding step, the strip 200 is wound around itself Nai > 1 circumferential turns stacked radially on each thick axial end 90, 92, 94, 96 of the self-sealing product layer 80, where i ranges from 1 to 4. The strip 200 is wound around itself Nbj > 1 circumferential turns stacked radially on each thin axial end 100, 102, 104 of the self-sealing product layer 80, where j ranges from 1 to M. For any value of i ranging from 1 to L, at least 50%, preferably at least 75%, and in this case 100% of the values of j ranging from 1 to M satisfy Nbj < Nai. In this specific case, the following conditions still hold: for each thick axial part 90 and 92, Na1 = Na2 = 5, for each thick axial part 94, 96, Na3 = Na4 = 4, and for each thin axial part 100, 102, 10 = Nb2 = Nb3 = 3.

[0171] It should be noted that for each value of i ranging from 1 to L, at least 50%, preferably at least 75%, and in this case 100% of the values of j ranging from 1 to M on the one hand satisfy Nai / Nbj ≥ 1.20, and on the other hand satisfy Nai / Nbj ≤ 3.00, preferably Nai / Nbj ≤ 2.75, more preferably Nai / Nbj ≤ 2.50.

[0172] To carry out this winding step, the winding pattern includes a plurality of parameters for changing the thickness of the self-sealing product layer 80 axially. These parameters include the winding pitch of the strip 200, the winding speed of the strip 200 relative to the device for applying the strip 200, the axial movement speed of the tire 10 relative to the device for applying the strip 200 on the tire 10, the extrusion rate of the device for extruding the strip 200, the width of the strip 200 or the thickness of the strip 200. It is possible to choose to change only one of these parameters or to change several parameters simultaneously. Advantageously, in this case, only the winding pitch of the strip 200 is changed, so as to change the thickness of the self-sealing product layer 80 axially over at least 50%, preferably at least 75%, more preferably at least 95%, and in this case 100% of the circumferential length of the self-sealing product layer 80, and to obtain Figure 3 the layer shown. Reference will now be made to Figure 4 a tire according to a second embodiment of the present invention. Elements similar to those of the first embodiment are denoted by the same reference numerals.

[0173] Compared with the tire according to the first embodiment, each thick axial part 90 to 96 respectively completely coincides with a part of each axial part 90' to 96' extending axially and respectively aligned with each main circumferential cut 52 to 58.

[0174] Furthermore, the self-sealing product layer does not include any thin axial portions 100, 102, 104. Therefore, each axial portion 100', 102', 104' extending axially aligned with each central rib 62, 64, 66, respectively, has a self-sealing product thickness of zero. Therefore, Eb1 = Eb2 = Eb3 = 0. Each axial portion 100', 102', 104' is axially arranged between two axially adjacent axial portions 90' to 96', and axially arranged between two axial portions 90” and 92”. In the method of manufacturing the tire 10 according to the second embodiment, what is changed is not the spacing of the strips, but the thickness of the strip 200, which is substantially zero between axially adjacent axial portions 90' to 96'. Therefore, the strip 200 is wound between the two axial ends 81, 82 when the strip 200 is interrupted (in this case, three times).

[0175] The present invention is not limited to the above-described embodiments.

[0176] Specifically, an embodiment can also be envisioned in which each central rib 62, 64, 66 does not contain any transverse incisions. In this case, it can be said that each central rib 62, 64, 66 has no incisions.

Claims

1. A tire (10), said tire (10) comprising: - Tread (14), said tread (14) comprising: - At least one circumferential cut (52, 54, 56, 58) referred to as the main circumferential cut, wherein the depth Ha of the circumferential cut (52, 54, 56, 58) satisfies Ha / Hs≥50%, where Hs is the tread height. - At least one rib (62, 64, 66), -Airtight inner layer (18), - A self-sealing product layer (80), said self-sealing product layer (80) extending circumferentially inward on a portion of the airtight inner layer (18), Characterized in that, over at least 50% of the circumferential length of the self-sealing product layer (80), the self-sealing product layer (80) comprises: - Axial portions (90', 92', 94', 96') extending axially aligned with the main circumferential cuts (52, 54, 56, 58), wherein the axial portions (90', 92', 94', 96') have an average thickness Ea > 0 for the self-sealing product. - Axial portions (100', 102', 104') extending axially aligned with the ribs (62, 64, 66), wherein the axial portions (100', 102', 104') have an average thickness Eb ≥ 0 for the self-sealing product, satisfying Eb <Ea。 2. The tire (10) according to the preceding claim, wherein, The axial width of the main circumferential cuts (52, 54, 56, 58) or each main circumferential cut (52, 54, 56, 58) is greater than or equal to 1.0 mm, preferably greater than or equal to 5.0 mm, more preferably greater than or equal to 8.0 mm, and even more preferably in the range of 8.0 mm to 20.0 mm.

3. The tire (10) according to any one of the preceding claims, wherein, The depth of the main circumferential cuts (52, 54, 56, 58) or each main circumferential cut (52, 54, 56, 58) ranges from 4.0 mm to the tread height, preferably from 5.0 mm to the tread height, and more preferably from 5.5 mm to the tread height.

4. The tire (10) according to any one of the preceding claims, wherein, The self-sealing product layer (80) includes at least one axial portion (90, 92, 94, 96) referred to as a thick axial portion, wherein the thick axial portion (90, 92, 94, 96) or each thick axial portion (90, 92, 94, 96) at least partially coincides with all or part of an axial portion (90', 92', 94', 96') or each axial portion (90', 92', 94', 96') extending axially aligned with the main circumferential cuts (52, 54, 56, 58) or each main circumferential cut (52, 54, 56, 58), and the thick axial portion (90, 92, 94, 96) or each thick axial portion The portions (90, 92, 94, 96) are defined axially by two adjacent inflection points (81, 82, 83, 84, 85, 86, 87, 88) on the radial inner surface curve (89) of the self-sealing product layer (80). The thickness of the thick axial portion (90, 92, 94, 96) increases from each inflection point in a direction axially toward the inside of the thick axial portion (90, 92, 94, 96). The axial width Wx of the thick axial portion satisfies Wx / Lax≥0.50, preferably Wx / Lax>1.00, where Lax is the axial width of the main circumferential cut (52, 54, 56, 58).

5. The tire (10) according to the preceding claim, wherein, Wx / Lax ≤ 4.00, preferably Wx / Lax ≤ 3.00, more preferably Wx / Lax ≤ 2.00, even more preferably Wx / Lax ≤ 1.50, and most preferably Wx / Lax ≤ 1.

25.

6. The tire (10) according to any one of the preceding claims, wherein, Ea ≥ 1.10 × Eb, preferably Ea ≥ 1.30 × Eb, and more preferably Ea ≥ 1.50 × Eb.

7. The tire (10) according to any one of the preceding claims, wherein, Ea≤5.00×Eb, preferably Ea≤4.00×Eb, and more preferably Ea≤2.50×Eb.

8. The tire (10) according to any one of the preceding claims, wherein, Ribs (62, 64, 66, 68, 70) or each rib (62, 64, 66, 68, 70) is defined axially by an inner axial end and an outer axial end, each selected from: - The axial ends (81, 82) of the tread (14), and - The inner or outer axial ends (521, 522, 541, 542, 561, 562, 581, 582) of the main circumferential cuts (52, 54, 56, 58). The inner and outer ends of the ribs (62, 64, 66, 68, 70) are adjacent to each other.

9. The tire (10) according to any one of the preceding claims, wherein The tread (14) includes: -N>1 main circumferential cuts (52, 54, 56, 58), wherein the depth Hai of each main circumferential cut (52, 54, 56, 58) satisfies Hai / Hs≥50%, preferably Hai / Hs≥75%, more preferably Hai / Hs≥90%, and i ranges from 1 to N, where N is the total number of main circumferential cuts on the tire. -Q = N-1 ≥ 1 central rib (62, 64, 66), where each central rib (62, 64, 66) is axially arranged between two adjacent main circumferential cuts (52, 54, 56, 58) and is axially defined by the two adjacent main circumferential cuts (52, 54, 56, 58), and Q is the total number of central ribs present on the tire. The self-sealing product layer (80) includes: -N>1 axial portions (90', 92', 94', 96'), each of which extends axially aligned with one of N main circumferential cuts (52, 54, 56, 58), and each having an average thickness Eai>0 for the self-sealing product. -Q = N-1 ≥ 1 axial portion (100', 102', 104'), each of which extends axially aligned with one of Q central ribs (62, 64, 66) or Q central ribs (62, 64, 66), and each having an average thickness Ebj ≥ 0 for the self-sealing product, where j ranges from 1 to Q, and the axial portion (100', 102', 104') has an average thickness Ebj ≥ 0 for the self-sealing product. The self-sealing product layer (80) is arranged axially between two adjacent adjacent axial portions (90', 92', 94', 96') extending along the axial direction and between two of the N main circumferential cuts (52, 54, 56, 58), such that for each value of i ranging from 1 to N, at least 50% of the value of j ranging from 1 to Q, preferably at least 75% of the value of j ranging from 1 to Q, and more preferably 100% of the value of j ranging from 1 to Q, satisfy Ebj. <Eai。 10. The tire (10) according to the preceding claim, wherein, The central ribs (62, 64, 66) or each central rib (62, 64, 66) either do not include transverse cuts or include transverse cuts (74, 75, 76), and the number of transverse cuts in the central ribs (62, 64, 66) or each central rib (62, 64, 66) is at least 50%, preferably at least 75%, more preferably 100%, and each transverse cut (74, 75, 76) satisfies at least one of the following conditions: - The transverse cuts (74, 75, 76) of the central ribs (62, 64, 66) have a width strictly less than 1.6 mm, preferably strictly less than 1.0 mm, and more preferably strictly less than 0.7 mm. - The depth H of the transverse cuts (74, 75, 76) of the central ribs (62, 64, 66) satisfies H / Hs<50%, preferably H / Hs≤30%.

11. The tire (10) according to claim 9 or 10, wherein, The tread (14) includes: - An axial central portion (P0), comprising N main circumferential cuts (52, 54, 56, 58) and Q central ribs (62, 64, 66), wherein the axial central portion (P0) is defined axially by each axially outer end (521, 541) of each outermost axial main circumferential cut (52, 54), and - The first axially-side part and the second axially-side part (P1, P2), which are arranged axially outside the axially central part (P0) and one is arranged axially on each side of the axially central part (P0) with respect to the median plane (M) of the tire (10). The first axially-side part and the second axially-side part (P1, P2) each extend axially from each axially end (41, 42) of the tread (14) to each axially outermost axially main circumferential cut (52, 54)'s each axially outer end (521, 541). The first axially-side part and the second axially-side part (P1, P2) each respectively include a first side rib part and a second side rib part (68, 70). At least one of the first side rib part and the second side rib part (68, 70) includes at least one transverse cut (77, 78). The transverse cut (77, 78) has a depth Ht that satisfies Ht / Hs≥50%, preferably Ht / Hs≥75%. The self-sealing product layer (80) includes at least one axially extending axial part (90”, 92”) that is axially aligned with the first side rib part or the second side rib part (68, 70). The first side rib part or the second side rib part (68, 70) includes at least one transverse cut (77, 78). The transverse cut (77, 78) has a depth Ht that satisfies Ht / Hs≥50%, preferably Ht / Hs≥75%, and has an average thickness Ec of the self-sealing product >0, such that at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, more preferably 100% of the values of j ranging from 1 to Q satisfy Ebj<Ec.

12. The tire (10) according to the preceding claim, wherein, The first side rib part and the second side rib part (68, 70) each include at least one transverse cut (77, 78). The transverse cut (77, 78) has a depth Ht that satisfies Ht / Hs≥50%, preferably Ht / Hs≥75%. The self-sealing product layer (80) includes a first axial part and a second axial part (90”, 92”). The first axial part and the second axial part (90”, 92”) respectively extend axially in alignment with the first side rib part and the second side rib part (68, 70), and respectively have an average thickness Ec1, Ec2 of the self-sealing product that satisfy Ec1>0 and Ec2>0, and at least 50% of the values of j ranging from 1 to Q, preferably at least 75% of the values of j ranging from 1 to Q, more preferably 100% of the values of j ranging from Q satisfy Ebj<Ec1 and Ebj<Ec2.

13. The tire (10) according to claim 11 or 12, wherein, The transverse cut (77, 78) or each transverse cut (77, 78) has a width greater than or equal to 0.7 mm, preferably greater than or equal to 1.0 mm, more preferably greater than or equal to 1.6 mm.

14. The tire (10) according to any one of claims 11 to 13, wherein, The transverse cut (77, 78) or each transverse cut (77, 78) has a depth ranging from 2.0 mm to the tread pattern height, preferably from 4.0 mm to the tread pattern height, more preferably from 5.0 mm to the tread pattern height.

15. The tire (10) according to any one of the preceding claims, wherein, Each axial end (81, 82) of the self-sealing product layer (80) is arranged relative to each axial end (41, 42) of the tread (14) at a distance less than or equal to 20% of the axial width of the tread (14), preferably less than or equal to 10%, and preferably arranged axially inside each axial end (81, 82) of the tread (14).

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