Tyre comprising a flexible tread

Abstract

The invention relates to a tyre (10) comprising first, second and third circumferential grooves (62, 64, 66), transverse grooves (72) substantially parallel to one another and intersecting each first, second and third circumferential groove (62, 64, 66), first, second and third circumferential columns (22, 24, 28) of blocks (20) and an additional circumferential column (30, 32) of blocks (20). The leading edge (202) of each block of each first, second and third circumferential column (22, 24, 28) forms, with the circumferential direction (X), an angle (D1, D2, D3) strictly greater than the angle (A1, A2) formed by the mean direction of the leading edge (202) of each block of the additional circumferential column (30, 32).

Description

Pneumatic tire with a flexible tread

[0001] The present invention relates to a tire. By tire is meant a bandage intended to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized to a pressure higher than atmospheric pressure. A tire according to the invention has a structure of substantially toroidal shape of revolution around a main axis of the tire.

[0002] The state of the art is known for competition tires intended for rally events in which vehicles equipped with such tires drive on dirt surfaces. Well-known tires are the MICHELIN LATITUDE CROSS ® tires.

[0003] For many years, rally stages, also known as special stages, were relatively long. In order to obtain tires durable enough to withstand the entirety of each stage, tires with relatively rigid treads were preferred. More recently, the stages have been shortened, making the relatively high tread stiffness unnecessary.

[0004] The invention aims to make the tire more efficient on special stages requiring a less rigid tread.

[0005] To this end, the subject of the invention is a tire having an inner side and an outer side imposed when the tire is mounted on a vehicle, the tire comprising a tread comprising first and second axial edges arranged respectively on the inner and outer side, the tread comprising a plurality of loaves and a plurality of grooves comprising: - at least first, second and third circumferential grooves arranged so that there is at least one first, second and third substantially circumferential line passing respectively in each first, second and third circumferential groove extending continuously over a circumference of the tire without cutting any of the plurality of loaves, each first, second or third substantially circumferential line having an axial width greater than or equal to 2 mm, each first, second and third circumferential groove being arranged in an axial portion of axial width equal to at most 75% of the axial width of the tread and extending from the first axial edge, - at least the first, second, third circumferential columns of loaves of the plurality of loaves, - transverse grooves extending continuously from the first axial edge to the second axial edge of the tread substantially parallel to each other, each transverse groove intersecting each first, second and third circumferential groove, - at least one additional circumferential column of loaves of the plurality of loaves, the or each additional circumferential column being the circumferential column axially closest to the second axial edge among the first, second, third circumferential columns of loaves and said additional circumferential column, each loaf of the plurality of loaves comprising a leading edge, the leading edge of each loaf of at least each first, second and third circumferential column of loaves has a mean direction forming, with the circumferential direction of the tire, an angle strictly greater than the angle formed by the mean direction of the leading edge of each loaf of the or each additional circumferential column of loaves with the circumferential direction of the tire.

[0006] The presence of the first, second and third circumferential grooves in the axial portion of axial width equal to at most 75% of the axial width of the tread and extending from the first axial edge combined with the presence of the transverse grooves extending from the first axial edge to the second axial edge crossing the first, second and third circumferential grooves makes it possible to ensure relatively significant flexibility of the tread in this axial portion which is the one which is most often in contact with the ground due to the camber of motor vehicles. Indeed, these first, second and third circumferential grooves act as hinges oriented in the circumferential direction allowing axial flexion of the tread which better matches the profile of the ground on which the tire rolls.This improved adaptability of the tread thus improves the tire's performance. The transverse grooves ensure circumferential flexion across the entire width of the tread and therefore better match the ground profile. For example, tests conducted on earthy ground between a vehicle equipped with the state-of-the-art tires described above and the same vehicle equipped with the tires according to the invention resulted in a gain of one second per kilometer. Such a time saving is considerable.

[0007] A substantially circumferential line is a line forming at any point on the line an angle less than or equal to 5° with the circumferential direction of the tire.

[0008] The presence of the first, second and third circumferential columns of loaves allows for efficient transmission of forces in the circumferential direction due to the orientation of the leading edge of each loaf of these circumferential columns. These loaves are essentially stressed in a straight line, whether during acceleration or braking, due to the negative camber usually encountered on motor vehicles, in particular motor racing vehicles, which results in greater stress on the portion of the tread arranged on the inner side of the vehicle.

[0009] In addition, the orientation of the leading edge of each loaf of the additional circumferential column allows for efficient transmission of drift forces. Such drift forces are very frequently encountered in rallying on earthy ground when cornering. Indeed, when cornering, the load transfer associated with the kinematics of the vehicle's running gear results in greater stress on the portion of the tread arranged on the outside of the vehicle and therefore on the loaves of the additional circumferential column. A circumferential column of loaves means a column in which one passes from one loaf of the column to another identical loaf of the column by translation in the circumferential direction. Within the same circumferential column of loaves, one can have a single type of loaf, i.e. two circumferentially consecutive loaves of the column are identical.It is also possible to have several different types of bread, that is to say that at least two identical breads of the column and of a first type are circumferentially separated by at least one bread of a second type, different from the first type. By type, we mean the geometric shape of the bread, whether its external geometric shape or any incisions that may be made therein.

[0010] The tire according to the invention is a tire having an inner side and an outer side imposed when it is mounted on the vehicle. This means that the tire is designed so that one of its sides is arranged on the inner side and the other of its sides is arranged on the outer side. By outer side is meant the side of the tire entirely visible from the outside of the vehicle when the tire is mounted on the vehicle. By inner side is meant the side of the tire facing the wheel arch of the vehicle on which it is mounted. Generally, the tire has a marking indicating the inner side and the outer side.

[0011] A tire generally has several edges defining a tire contour. These edges can be straight or curved. There is a leading edge, a trailing edge, and lateral edges. The leading edge is the edge that first comes into contact with the ground when the tire rotates in its forward direction. The trailing edge is the edge that last comes into contact with the ground when the tire rotates in its forward direction of rotation. The lateral edges are the edges connecting the leading and trailing edges.

[0012] The angle between two directions is the angle, in absolute value, the smallest of the two angles defined between a reference direction, most often the circumferential direction of the tire and the other direction.

[0013] The mean direction formed by an edge is the straight direction connecting the two ends of the edge.

[0014] In the case of a competition tire, the determination of the axial width of the tread is made on an unmounted and uninflated tire by measuring the axial distance between the edges forming the first and second axial edges of the tread, these axial edges forming the boundary between the tread and the sidewalls of the tire. In the case of a competition tire, each of these first and second axial edges includes the lateral edges of the axially outermost blocks of the tread.

[0015] In the case of a tire not intended for competition, the rolling surface on a tire mounted on a measuring rim and inflated to the nominal pressure (250 kPa or 290 kPa depending on whether it is a standard or reinforced tire) within the meaning of the ETRTO standard manual, 2021 can be determined as being the surface in contact with the ground when the tire is loaded to 80% of its load capacity within the meaning of the ETRTO standard manual, 2021, a load then representing conditions of use normally encountered.Another method may consist, on a tire mounted on a measuring rim, unloaded and inflated to the nominal pressure (250 kPa or 290 kPa depending on whether it is a standard or reinforced tire) within the meaning of the ETRTO (“European Tire and Rim Technical Organization”) standard manual, 2021, in determining the axial limits of the rolling surface, for example, by considering that each axial limit of the rolling surface passes through the point for which the angle between the tangent to the rolling surface and a straight line parallel to the axial direction passing through this point is equal to 30°. When there are several points on a meridian section plane for which the said angle is equal in absolute value to 30°, the radially outermost point is retained.

[0016] The invention applies particularly to competition tires for motor vehicles. Competition means officially timed events and not free driving, sometimes known as "track days" or "HDPE" (High Driving Performance Events), which covers officially untimed events.

[0017] The invention applies very particularly and very preferentially to rally competition tires and more preferentially to rally competition tires at least on earthy and / or gravelly and / or muddy ground and very preferentially in rally competition on earthy ground.

[0018] The tire according to the invention has a substantially toric shape around an axis of revolution substantially coincident with the axis of rotation of the tire. This axis of revolution defines three directions conventionally used by those skilled in the art: an axial direction, a circumferential direction and a radial direction.

[0019] The tread surface of the tire is the area of ​​the tread through which the tire comes into contact with the ground when rolling over that ground.

[0020] Axial direction means the direction substantially parallel to the axis of revolution of the tire, i.e. the axis of rotation of the tire.

[0021] Circumferential direction means the direction which is substantially perpendicular to both the axial direction and a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[0022] Radial direction means the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[0023] By median plane of the tire (noted M), we mean the plane perpendicular to the axis of rotation of the tire which is located at the axial midpoint of the two beads and passes through the axial center of the crown reinforcement.

[0024] The equatorial circumferential surface of the tire means, in a meridian section plane, the surface passing through the equator of the tire, perpendicular to the median plane and to the radial direction. The equator of the tire is, in a meridian section plane (plane perpendicular to the circumferential direction and parallel to the radial and axial directions) the axis parallel to the axis of rotation of the tire and located equidistant between the radially outermost point of the tread intended to be in contact with the ground and the radially innermost point of the tire intended to be in contact with a support, for example a rim.

[0025] Meridian plane means a plane parallel to and containing the axis of rotation of the tire and perpendicular to the circumferential direction.

[0026] By radially inner, respectively radially outer, is meant closer to the axis of rotation of the tire, respectively further from the axis of rotation of the tire. By axially inner, respectively axially outer, is meant closer to the median plane of the tire, respectively further from the median plane of the tire.

[0027] By bead is meant the radial portion of the tire intended to allow the tire to be attached to a mounting support, for example a wheel comprising a rim. Thus, each bead is in particular intended to be in contact with a hook on the rim allowing it to be attached.

[0028] Any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from more than a to less than b (i.e., excluding the limits a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (i.e., including the strict limits a and b).

[0029] A cutout is either a groove or an incision and forms a space opening onto the rolling surface.

[0030] An incision or groove has, on the rolling surface, two main characteristic dimensions: a width and a curvilinear length such that the curvilinear length is at least twice the width. An incision or groove is therefore delimited by at least two main lateral faces determining its curvilinear length and connected by a bottom face, the two main lateral faces being distant from each other by a non-zero distance, called the width of the cut.

[0031] The width of a cutout is, on a new tire, the maximum distance between the two main lateral faces measured, in the case where the cutout does not include a chamfer, at a radial dimension coincident with the rolling surface, and in the case where the cutout includes a chamfer, at the radial dimension most radially outer of the cutout and radially inner of the chamfer. The width is measured substantially perpendicular to the main lateral faces.

[0032] An incision is such that the distance between the main lateral faces is suitable to allow at least partial contact of the main lateral faces delimiting said incision when passing through the contact area, in particular when the tire is in new condition.

[0033] A groove is such that the distance between the main lateral faces is such that these main lateral faces cannot come into contact with each other, particularly when the tire is new.

[0034] A cutout can be transverse or circumferential.

[0035] A transverse cut is such that the cut extends in a mean direction forming an angle strictly greater than 30°, preferably greater than or equal to 45° with the circumferential direction of the tire. The mean direction is the shortest curve joining the two ends of the cut and parallel to the tread surface. A transverse cut may be continuous, i.e. not be interrupted by a loaf or other cutout so that the two main lateral faces determining its length are uninterrupted along the length of the transverse cutout. A transverse cutout may also be discontinuous, i.e. interrupted by one or more loaves and / or one or more cutouts so that the two main lateral faces determining its length are interrupted by one or more loaves and / or one or more cutouts.

[0036] A circumferential cutout is such that the cutout extends in a mean direction forming an angle less than or equal to 30°, preferably less than or equal to 10° with the circumferential direction of the tire. The mean direction is the shortest curve joining the two ends of the cutout and parallel to the rolling surface. In the case of a continuous circumferential cutout, the two ends coincide with each other and are joined by a curve making a complete turn of the tire. A circumferential cutout may be continuous, that is to say not be interrupted by a loaf or another cutout so that the two main lateral faces determining its length are uninterrupted over the entire turn of the tire.A circumferential cutout may also be discontinuous, i.e. interrupted by one or more loaves and / or one or more cutouts so that the two main lateral faces determining its length are interrupted by one or more loaves and / or one or more cutouts over the entire circumference of the tire.

[0037] In embodiments, the or each circumferential cutout is provided with chamfers. A chamfer of a circumferential cutout may be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a flat face inclined relative to the axially inner and outer face which it extends to the axially inner or outer edge axially delimiting the circumferential cutout. A rounded chamfer is formed by a curved face connecting tangentially to the axially inner or outer face which it extends. A chamfer of a circumferential cutout is characterized by a height and a width equal respectively to the radial distance and the axial distance between the common point between the axially inner or outer face extended by the chamfer and the axially inner or outer edge axially delimiting the circumferential cutout.

[0038] In embodiments, the or each transverse cutout is provided with chamfers. In other words, each transverse cutout being delimited radially by faces circumferentially delimiting said transverse cutout and connected to each other by a bottom face delimiting radially inwardly said transverse cutout. A chamfer of a transverse cutout may be a straight chamfer or a rounded chamfer. A straight chamfer is formed by a flat face inclined relative to the face that it extends to the edge circumferentially delimiting the transverse cutout. A rounded chamfer is formed by a curved face connecting tangentially to the face that it extends. A chamfer of a transverse cutout is characterized by a height and a width equal respectively to the radial distance and to the distance in a direction perpendicular to the faces between the common point between the face extended by the chamfer and the edge circumferentially delimiting the transverse cutout.

[0039] The depth of a cut is, on a new tire, the maximum radial distance between the bottom of the cut and its projection onto the ground when the tire is rolling. The maximum value of the depths of the cuts is called the tread height.

[0040] In preferred embodiments, each first, second, third substantially circumferential line has an axial width greater than or equal to 5 mm and more preferably greater than or equal to 7 mm. Thus, the hinge effect of the first, second, and third circumferential grooves is favored.

[0041] In preferred embodiments using optimal positioning of the first, second and third circumferential grooves in order to improve the adaptability of the pneumatic tread, in particular in a straight line, each first, second and third circumferential groove is arranged in an axial portion of axial width equal to at most 70% of the axial width of the tread and extending from the first axial edge.

[0042] In advantageous but optional embodiments, the leading edge of each bread of at least each first, second and third circumferential column of breads has a mean direction forming an angle greater than or equal to 50°, preferably 60° with the circumferential direction of the tire.

[0043] Thus, by modifying the angle formed by the leading edge and the circumferential direction of each bread of the first, second and third circumferential columns, and here by increasing it, it is possible to optimize the position of the leading edge so as to position it as perpendicular as possible to the general direction of the forces in a straight line, which allows improved transmission of the forces and therefore increased traction.

[0044] In advantageous but optional embodiments, the leading edge of each loaf of the or each additional circumferential column of loaves has a mean direction forming an angle less than or equal to 60°, preferably 50° with the circumferential direction of the tire.

[0045] Thus, by modifying the angle formed by the leading edge and the circumferential direction of each bread of the or each additional circumferential column, and here reducing it, it is possible to optimize the position of the leading edge so as to position it as perpendicular as possible to the general direction of the forces when cornering, which allows improved transmission of the forces and therefore increased traction.

[0046] Advantageously, the first circumferential groove is the circumferential groove among the first, second, third circumferential grooves arranged axially closest to the first axial edge, the third circumferential groove is the circumferential groove among the first, second, third circumferential grooves arranged axially closest to the second axial edge, the second circumferential groove is arranged axially between the first circumferential groove and the third circumferential groove.

[0047] In preferred embodiments utilizing optimal positioning of the first, second, and third circumferential grooves to improve tire tread adaptability: - the first circumferential groove is arranged axially in a first axial portion extending axially between axial limits arranged at 3% and 25%, preferably at 5% and 20% of the axial width of the tread from the first axial edge, and / or - the second circumferential groove is arranged axially in a second axial portion extending axially between axial limits arranged at 19% and 42%, preferably at 23% and 39% of the axial width of the tread from the first axial edge, and / or - the third circumferential groove is arranged axially in a third axial portion extending axially between axial limits arranged at 42% and 70%, preferably at 46% and 66% of the axial width of the tread from the first axial edge.

[0048] Advantageously, the first circumferential column of breads is the column of breads among the first, second, third circumferential columns of breads arranged axially closest to the first axial edge, the third circumferential column of breads is the column of breads among the first, second, third circumferential columns of breads arranged axially closest to the second axial edge, the second circumferential column of breads is arranged axially between the first circumferential column and the third circumferential column.

[0049] In some embodiments: - each bread of the first circumferential column is delimited axially by the first circumferential groove and the first axial edge, - each bread of the second circumferential column being axially delimited by the first and second circumferential grooves, - each bread of the third circumferential column being delimited axially at least in part by the third circumferential groove.

[0050] In advantageous but optional embodiments, each transverse groove extending axially in an axially variable main direction, the angle formed by the main direction of each transverse groove and the circumferential direction of the tire has: - a non-zero monotonic variation between the first and second axial edges of the tread, or - is constant over at least one axial portion between the first and second axial edges of the tread and a non-zero monotonic variation over at least one complementary axial portion between the first and second axial edges of the tread.

[0051] By axially variable direction, we mean that the principal direction of each transverse groove varies as one moves axially along each transverse groove.

[0052] The complementary portions are such that, taken together, the complementary portions extend fully from the first axial edge to the second axial edge of the tread.

[0053] A constant angle corresponds to zero variation in the angle.

[0054] By non-zero monotonic variation, we mean that the angle increases only or decreases only between the first and second axial edges of the tread.

[0055] Thus, each transverse groove delimiting the leading edges of the breads of the different columns of breads, the non-zero monotonic variation makes it possible to obtain a variation in traction as a function of the angle of rotation of the tire around the axis of the running gear and therefore to allow continuity of traction between straight lines and bends.

[0056] More preferably, the angle formed by the main direction of each transverse groove and the circumferential direction of the tire at the first axial edge is greater than the angle formed by the main direction of each transverse groove and the circumferential direction of the tire at the second axial edge. Thus, in the case of a non-zero monotonic variation, the angle decreases only from the first axial edge to the second axial edge of the tread or over the corresponding portion between the first axial edge and the second axial edge of the tread.

[0057] In preferred embodiments, the angle formed by the mean direction of the leading edge of each bread of at least one given circumferential column of breads with the circumferential direction is strictly greater than the angle formed, with the circumferential direction, by the mean direction of the leading edge of each bread of the circumferential column of breads which is axially adjacent to it, the axially adjacent column being closer to the second axial edge than the given circumferential column of breads.More preferably, for at least 50% of the pairs of circumferential columns of breads axially adjacent to each other, even more preferably for at least 75% of the pairs of circumferential columns of breads axially adjacent to each other and here for each pair of circumferential columns of breads axially adjacent to each other, the angle formed by the average direction of the leading edge of each bread of a first of the circumferential columns of breads of the pair with the circumferential direction is strictly greater than the angle formed, with the circumferential direction, by the average direction of the leading edge of each bread of the second circumferential column of breads of the pair, the second circumferential column of breads of each pair being the column closest to the second axial edge among the first and second circumferential columns of breads of said pair.

[0058] In preferred embodiments, the angle formed by the main direction of each transverse groove and the circumferential direction of the tire at the first axial edge is between 70° and 90° and the angle formed by the main direction of each transverse groove and the circumferential direction of the tire at the second axial edge is between 30° and 60°.

[0059] In preferred embodiments, the angle formed by the average direction of the leading edge of each bread of the first circumferential column with the circumferential direction is greater than or equal to the angle formed by the average direction of the leading edge of each bread of the second circumferential column with the circumferential direction which is strictly greater than the angle formed by the average direction of the leading edge of each bread of the third circumferential column with the circumferential direction.

[0060] Thus, each transverse groove delimiting the leading edges of the breads of the different columns of breads, excellent traction in a straight line is ensured due to the relatively high angle between the leading edges of the breads located near the first edge corresponding to the inner side stressed in a straight line and the circumferential direction. Excellent traction in turns is also ensured due to the relatively low angle between the leading edges of the breads located near the second edge corresponding to the outer side stressed in turning and the circumferential direction.

[0061] Preferably, the leading edge of each bread of each first and second circumferential column has a mean direction forming an angle ranging from 70° to 90° with the circumferential direction. Preferably, the leading edge of each bread of the third circumferential column has a mean direction forming an angle ranging from 50° to 70° with the circumferential direction. Preferably, the leading edge of each bread of the or each additional circumferential column has a mean direction forming an angle ranging from 30° to 60° with the circumferential direction.

[0062] In advantageous but optional embodiments, the tread comprises a fourth circumferential column of loaves of the plurality of loaves arranged axially between the second and third circumferential columns of loaves, the leading edge of each loaf of the fourth circumferential column of loaves having a mean direction forming an angle strictly greater than the angle formed by the mean direction of the leading edge of each loaf of the or each additional circumferential column of loaves.

[0063] In advantageous but optional embodiments, the angle formed by the average direction of the leading edge of each bread of the fourth circumferential column with the circumferential direction is strictly greater than the angle formed by the average direction of the leading edge of each bread of the third circumferential column with the circumferential direction.

[0064] Preferably, the leading edge of each bread of the fourth circumferential column has a mean direction forming an angle ranging from 65° to 85° with the circumferential direction.

[0065] Preferably, each bread of the fourth circumferential column is axially delimited by the second and third circumferential grooves.

[0066] In still other embodiments, it may be envisaged that the tread comprises a fifth or even a sixth circumferential column of loaves of the plurality of loaves arranged axially between the second and third circumferential column of loaves, the loaves of this fifth or of these fifth and sixth columns, the leading edge of each of this fifth circumferential column of loaves or of these fifth and sixth circumferential columns of loaves having a mean direction forming an angle strictly greater than the angle formed by the mean direction of the leading edge of each loaf of the or each additional circumferential column of loaves.

[0067] In advantageous but optional embodiments, each loaf of the or each additional circumferential column of loaves is delimited by at least one oblique groove intersecting at least two circumferentially consecutive transverse grooves and being arranged so that there is no circumferential line extending continuously over a circumference of the tire passing through the or each oblique groove delimiting each loaf of said additional circumferential column of loaves without intersecting the loaves of said additional circumferential column of loaves.

[0068] Thus, each oblique groove does not form a hinge unlike the first, second and third circumferential grooves.

[0069] Two circumferentially consecutive transverse grooves are such that no other transverse groove is circumferentially arranged between said two circumferentially consecutive transverse grooves.

[0070] Optionally, the tread comprises first and second additional circumferential columns of loaves of the plurality of loaves, each first and second additional circumferential column being axially closer to the second axial edge than the first, second, third circumferential columns of loaves, the leading edge of each loaf of at least each first, second and third circumferential column of loaves has a mean direction forming an angle strictly greater than the angle formed by the mean direction of the leading edge of each loaf of each first and second additional circumferential column of loaves, each loaf of the first additional circumferential column of loaves being axially delimited by two oblique grooves crossing two circumferentially consecutive transverse grooves,each loaf of the second additional circumferential column of loaves being axially delimited by an oblique groove crossing two circumferentially consecutive transverse grooves and the second axial edge, each loaf of each first and second additional circumferential column of loaves being arranged so that there is no circumferential line extending continuously over a circumference of the tire passing through the or each oblique groove delimiting each loaf of each first and second additional circumferential column of loaves without intersecting the loaves respectively of each first and second additional circumferential column of loaves.,

[0071] In advantageous but optional embodiments, the second additional circumferential column being arranged axially outside the first additional circumferential column, the angle formed by the average direction of the leading edge of each bread of the first additional circumferential column with the circumferential direction is strictly greater than the angle formed by the average direction of the leading edge of each bread of the second additional circumferential column with the circumferential direction.

[0072] In advantageous but optional embodiments, the leading edge of each bread of each first and second additional circumferential column of breads has a mean direction forming an angle less than or equal to 60°, preferably 50° with the circumferential direction of the tire.

[0073] As already indicated, by modifying the angle formed by the leading edge and the circumferential direction, and here reducing it, the transmission of forces is improved and therefore the traction is increased.

[0074] In advantageous but optional embodiments, each first and second circumferential column of breads comprises a single bread between two circumferentially consecutive transverse grooves.

[0075] The presence of a single bread between two circumferentially consecutive transverse grooves makes it possible to give a relatively large length in the circumferential direction to the breads of each first and second circumferential column of breads and therefore to limit any possible tearing of these breads which are heavily stressed in a straight line, especially during acceleration and braking phases.

[0076] In advantageous but optional embodiments, the third circumferential column of loaves comprises at least two loaves, preferably only two loaves, between two circumferentially consecutive transverse grooves.

[0077] The loaves of the third circumferential column of loaves being further away from the inner side than those of each first and second circumferential column of loaves, the loaves of the third circumferential column of loaves are less stressed than those of each first and second circumferential column of loaves and therefore less sensitive to possible tearing. Thus, it is possible to reduce their length in the circumferential direction and therefore maximize the number of leading edges which come into contact with the ground by increasing their number between two circumferentially consecutive transverse grooves.

[0078] Preferably, the leading edge of at least a portion of the loaves of the third circumferential column of loaves, preferably of at least 50% of the loaves of the third circumferential column of loaves and more preferably of at least 75% of the loaves of the third circumferential column of loaves has a curvilinear length strictly greater than the curvilinear length of each lateral edge of said loaf.

[0079] The greater the curvilinear length of the leading edge, the better the traction and braking performance.

[0080] In embodiments in which the tread comprises a fourth circumferential column of loaves arranged axially between the second and third circumferential columns of loaves, the fourth circumferential column of loaves comprises at least two loaves, preferably only two loaves, between two circumferentially consecutive transverse grooves.

[0081] Preferably, the leading edge of at least a portion of the loaves of the fourth circumferential column of loaves, preferably of at least 50% of the loaves of the fourth circumferential column of loaves and more preferably of at least 75% of the loaves of the fourth circumferential column of loaves has a curvilinear length strictly greater than the curvilinear length of each lateral edge of said loaf.

[0082] Here again, the multiplication of the breads between two circumferentially consecutive transverse grooves as well as the maximization of the curvilinear length of the leading edges of the breads ensures good performance in traction and braking.

[0083] Preferably, the additional circumferential column of breads comprises a single bread between two circumferentially consecutive transverse grooves.

[0084] In the case where the tread comprises first and second additional circumferential columns of breads, each first and second additional circumferential column of breads comprises a single bread between two circumferentially consecutive transverse grooves.

[0085] In a similar manner to the first and second circumferential columns of breads, the presence of a single bread between two circumferentially consecutive transverse grooves makes it possible to confer a relatively large length in the circumferential direction to the breads of each first and second additional circumferential column of breads and therefore to limit any possible tearing of these breads which are heavily stressed when turning.

[0086] In embodiments particularly suited to competition tires, in particular rally competition tires, the width of each circumferential groove is greater than or equal to 2 mm, preferably ranging from 5 mm to 15 mm and more preferably ranging from 7 mm to 12 mm.

[0087] Still in embodiments particularly suited to competition tires, in particular rally competition tires, the width of each oblique groove is greater than or equal to 2 mm, preferably ranging from 5 mm to 15 mm and more preferably goes from 7 mm to 12 mm.

[0088] Still in embodiments particularly suited to competition tires, in particular rally competition tires, the width of each transverse groove is greater than or equal to 2 mm, preferably ranging from 5 mm to 15 mm and more preferably ranging from 7 mm to 12 mm.

[0089] Still in embodiments particularly suited to competition tires, particularly rally competition tires, the tread height is greater than or equal to 7 mm, preferably ranging from 9 mm to 16 mm.

[0090] Still in embodiments particularly suited to competition tires, in particular rally competition tires, the surface notch rate of the tread associated with the grooves having a width greater than or equal to 2 mm, preferably 4 mm, ranges from 35% to 55%, preferably from 40% to 50%.

[0091] Still in embodiments particularly suited to competition tires, in particular rally competition tires, the volumetric notch rate of the tread associated with the grooves having a width greater than or equal to 2 mm, preferably 4 mm, ranges from 30% to 45%, preferably from 35% to 45%.

[0092] The surface notch rate associated with grooves is the ratio of: - the difference between the imaginary total area AT of the tread without said grooves and the contact area AC of the tread blocks, and - the imaginary total area AT of the contact imprint of the tread without said grooves.

[0093] The contact area of ​​the blocks is measured on a new tire. For example, the individual surface area of ​​the blocks can be measured manually. Alternatively, the new, unmounted and uninflated tire can be rolled on a smooth surface, such as a window, and the individual surface area of ​​each block optically measured to deduce the contact area.

[0094] The volumetric notch rate associated with grooves is the ratio of the total volume of said grooves of the tire in the new, unmounted and uninflated state to the total volume of the tread in the new state but not including any of said grooves. In order to measure such a volumetric notch rate, one of the methods described in WO2021 / 089958 may in particular be used.

[0095] The characteristics indicated above characterize the tire in new condition.

[0096] The invention also relates to a pair of a first and a second tires, each first and second tire being as defined above, a pair in which the tread of the first tire is symmetrical to the tread of the second tire with respect to a plane of symmetry substantially perpendicular to an axis of rotation common to the first and second tires.

[0097] Another subject of the invention is the use of a tire having an inner side and an outer side imposed when the tire is mounted on a vehicle, the tire comprising a tread comprising first and second axial edges arranged respectively on the inner and outer side, the tread comprising a plurality of loaves and a plurality of grooves comprising: at least first, second and third circumferential grooves arranged so that there is at least one first, second and third substantially circumferential line passing respectively in each first, second and third circumferential groove extending continuously over a circumference of the tire without cutting a loaf of the plurality of loaves, each first, second or third substantially circumferential line having an axial width greater than or equal to 2 mm ...second and third circumferential grooves being arranged in an axial portion of axial width equal to at most 75% of the axial width of the tread and extending from the first axial edge, at least of the first, second, third circumferential columns of loaves of the plurality of loaves, transverse grooves extending continuously from the first axial edge to the second axial edge of the tread substantially parallel to each other, each transverse groove intersecting each first, second and third circumferential groove, at least one additional circumferential column of loaves of the plurality of loaves, the or each additional circumferential column being the circumferential column axially closest to the second axial edge among the first, second, third circumferential columns of loaves and said additional circumferential column,each loaf of the plurality of loaves comprising a leading edge, the leading edge of each loaf of at least each first, second and third circumferential column of loaves has a mean direction forming, with the circumferential direction of the tire, an angle strictly greater than the angle formed by the mean direction of the leading edge of each loaf of the or each additional circumferential column of loaves with the circumferential direction of the tire or of a pair of first and, second tires as defined above in competition, preferably in rally competition and more preferably in rally competition at least on earthy and / or gravelly and / or muddy ground and very preferably in rally competition on earthy ground.

[0098] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and with reference to the drawings in which: Figure 1 is a schematic top view of a tread of the state-of-the-art tire MICHELIN LATITUDE CROSS ®, Figure 2 is a top view of a tire according to the invention, Figure 3 is a top view of a pair of first and second tires according to the invention, Figures 4 to 8 are detailed views of the same block of the tread of the tire of Figure 2, and Figures 9 to 12 are detailed views of blocks according to different embodiments.

[0099] The figures show a reference X, Y, Z corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions of a tire.

[0100] Figure 2 shows a tire, in accordance with the invention and designated by the general reference 10. The tire 10 has a substantially toric shape around an axis of revolution R substantially parallel to the axial direction Y. The tire 10 has the dimensions 17 / 65 R15 and is intended for use in competition, here in rally competition and more preferably in rally competition at least on earthy and / or gravelly and / or muddy ground and very preferably in rally competition on earthy ground. The size “17” relates to the theoretical width of the tread, here 17 cm, the size 65 relates to the theoretical diameter of the tire, here 65 cm and the size “R15” characterizes a radial carcass tire suitable for being mounted on a 15-inch wheel. In the various figures, the tire 10 is shown in new condition, that is to say not having yet been driven.

[0101] The tire 10 comprises a crown 12 comprising a tread 14 intended to come into contact with a ground during rolling via a rolling surface 16. The tread 14 comprises and is delimited by first and second axial edges 16A and 16B defining an axial width L of the rolling surface 16. Here L=178 mm. The tire 10 comprises an inner side INT and an outer side EXT imposed when the tire 10 is mounted on a vehicle. The first axial edge 16A is arranged on the inner side INT and the second axial edge 16B is arranged on the outer side EXT.

[0102] The tire 10 comprises two sidewalls 18 extending the crown 12 radially inwards. The tire 10 further comprises two beads (not shown) radially inwards to the sidewalls 18 intended to allow the tire 10 to be attached to a mounting support, for example a rim. Each sidewall 18 connects each bead to the crown 12.

[0103] The tread 14 comprises a plurality of loaves 20 and a plurality of cutouts 50 delimiting the plurality of loaves 20. The plurality of cutouts 50 comprises a plurality of grooves 60 and a plurality of incisions 80.

[0104] The plurality of grooves 60 comprises first, second and third circumferential grooves 62, 64, 66 arranged such that there is at least one first, second and third substantially circumferential line 63, 65, 67 passing respectively in each first, second and third circumferential groove 62, 64, 66 extending continuously over a circumference of the tire without cutting any of the plurality of loaves 20. Each first, second and third substantially circumferential line 63, 65, 67 has an axial width Le greater than or equal to 2 mm, preferably greater than or equal to 5 mm and here greater than or equal to 7 mm.

[0105] The first circumferential groove 62 is the circumferential groove among the first, second, third circumferential grooves 62, 64, 66 arranged axially closest to the first axial edge 16A. The third circumferential groove 66 is the circumferential groove among the first, second, third circumferential grooves 62, 64, 66 arranged axially closest to the second axial edge 16B. The second circumferential groove 64 is arranged axially between the first circumferential groove 62 and the third circumferential groove 66.

[0106] Each first, second and third circumferential groove 62, 64, 66 is arranged in an axial portion of axial width P equal to at most 75%, preferably at most 70% of the axial width L of the tread 14 and extending from the first axial edge 16A.

[0107] More specifically, the first circumferential groove 62 is arranged axially in a first axial portion P1 extending axially between axial limits arranged at 3% and 25%, preferably at 5% and 20% of the axial width L of the tread 14 from the first axial edge 16A. The second circumferential groove 64 is arranged axially in a second axial portion P2 extending axially between axial limits arranged at 19% and 42%, preferably at 23% and 39% of the width axial width L of the tread 14 from the first axial edge 16A. The third circumferential groove 66 is arranged axially in a third axial portion P3 extending axially between axial limits arranged at 42% and 70%, preferably at 46% and 66% of the axial width L of the tread 14 from the first axial edge 16A.

[0108] The plurality of grooves 60 also includes transverse grooves 72 extending continuously from the first axial edge 16A to the second axial edge 16B of the tread 14. The transverse grooves 72 extend substantially parallel to each other. Each transverse groove 72 extends axially in an axially variable main direction. Each transverse groove 72 intersects each first, second and third circumferential groove 62, 64, 66.

[0109] The angle formed by the main direction of each transverse groove 72 and the circumferential direction X is constant over an axial portion extending axially from the first axial edge 16A and the first circumferential line 63 and has a non-zero monotonic variation, and here strictly decreasing, over a complementary axial portion extending axially from the first circumferential line 63 and the second axial edge 16B. Furthermore, the angle DA formed by the main direction DR of each transverse groove 72 and the circumferential direction X of the tire at the first axial edge 16A is greater than the angle DB formed by the main direction DR of each transverse groove 72 and the circumferential direction X at the second axial edge 16B. The angle DA is between 70° and 90° and here substantially equal to 90°. The angle DB is between 30° and 60° and here substantially equal to 50°.

[0110] The plurality of loaves 20 comprises first, second, third, fourth circumferential columns of loaves 20 of the plurality of loaves 20, respectively designated by the references 22, 24, 28, 26, as well as first and second additional circumferential columns 30, 32 of loaves 20 of the plurality of 20. The first and second additional circumferential columns 30, 32 of loaves 20 are distinct from the first, second, third, fourth circumferential columns 22, 24, 28, 26 of loaves 20. Each additional circumferential column 30, 32 is axially closer to the second axial edge than the first, second, third circumferential columns 22, 24, 28, 26. The first circumferential column 22 of loaves 20 is the column of loaves among the first, second, third circumferential columns 22, 24, 26 of breads arranged axially closest to the first axial edge 16A.The third circumferential column 28 is the column of breads among the first, second, third and fourth circumferential columns 22, 24, 28, 26 of breads arranged axially closest to the second axial edge 16B. The second column. circumferential column 24 is arranged axially between the first circumferential column 22 and the third circumferential column 28. The fourth circumferential column 26 is arranged axially between the second circumferential column 24 and the third circumferential column 28.

[0111] Each bread 20 of the first circumferential column 22 is axially delimited by the first circumferential groove 62 and the first axial edge 16A. Each bread 20 of the second circumferential column 24 is axially delimited by the first and second circumferential grooves 62, 64. Each bread 20 of the third circumferential column 28 is axially delimited at least in part by the third circumferential groove 66. Each bread 20 of the fourth circumferential column 26 is axially delimited by the second and third circumferential grooves 64, 66.

[0112] Each first and second circumferential column 22, 24 comprises a single bread 20 between two circumferentially consecutive transverse grooves 72. Each third and fourth circumferential column 28, 26 comprises at least two breads 20, preferably only two breads 20, between two circumferentially consecutive transverse grooves 72.

[0113] Each first and second additional circumferential column 30, 32 of breads 20 is arranged axially outside the third circumferential column 28. The second additional circumferential column 32 is arranged axially outside the first additional circumferential column 30.

[0114] Each bread 20 of the first additional circumferential column 30 is axially delimited by two oblique grooves 68, 70 crossing two circumferentially consecutive transverse grooves 72. Each bread 20 of the second additional circumferential column 32 being axially delimited by an oblique groove 70 crossing two circumferentially consecutive transverse grooves 72 and the second axial edge 16B.

[0115] In Figure 2, two circumferential lines 69, 71 are shown passing through each oblique groove 68, 70. Each of these circumferential lines 69, 71 necessarily intersects the loaves 20 respectively of each first and second additional circumferential column 30, 32. Thus, more generally, each loaf 20 of each first and second additional circumferential column 30, 32 is arranged so that there is no substantially circumferential line extending continuously over a circumference of the tire passing through each oblique groove 68, 70 delimiting each loaf of each first and second additional circumferential column 30, 32 without intersecting the loaves 20 respectively of each first and second additional circumferential column 30, 32.

[0116] Each first and second additional circumferential column 30, 32 comprises a single bread 20 between two circumferentially consecutive transverse grooves 72.

[0117] Each bread 20 of the plurality of breads 20 comprises several edges defining a contour here substantially polygonal. Each bread 20 of each first, second, third, fourth circumferential column 22, 24, 28, 26 and of each first and second additional circumferential column 30, 32 comprises a leading edge 202, a trailing edge 204 and lateral edges 206, 208.

[0118] The leading edge 202 of each bread 20 of each first, second, third and fourth circumferential column 22, 24, 28, 26 has a mean direction forming, with the circumferential direction X, respectively an angle D1, D2, D3, D4 strictly greater than the angle A1, A2 formed by the mean direction of the leading edge 202 of each bread 20 respectively of each first and second additional circumferential column 30, 32 with the circumferential direction X.

[0119] The angle D1, D2, D4, D3, A1, A2 formed by the mean direction of the leading edge 202 of each bread 20 of each circumferential column 22, 24, 26, 28, 30, 32 with the circumferential direction X is strictly greater than the angle D2, D4, D3, A1, A2 formed, with the circumferential direction X, by the mean direction of the leading edge 202 of each bread 20 of the circumferential column 24, 26, 28, 30, 32 which is axially adjacent to it, each axially adjacent column 24, 26, 28, 30, 32 to a given circumferential column 22, 24, 26, 28, 30, 32 being closer to the outer side EXT than each given circumferential column 22, 24, 26, 28, 30, 32 corresponding.

[0120] The leading edge 202 of 100% of the breads 20 of each third and fourth circumferential column 28, 26 has a curvilinear length strictly greater than the curvilinear length of each lateral edge 206, 208 of said bread 20.

[0121] Each angle D1, D2, D3, D4 is greater than or equal to 50°, preferably greater than or equal to 60°. Angle D1 is greater than or equal to angle D2. Angle D2 is strictly greater than angle D3. Angle D4 is strictly greater than angle D3. In this case, each angle D1, D2 ranges from 70° to 90°, angle D3 ranges from 50° to 70° and angle D4 ranges from 65° to 85°. D1=90°, D2=85°, D3=60° and D4=75°.

[0122] Each angle A1, A2 is less than or equal to 60°, preferably less than or equal to 50°. Angle A1 is strictly greater than angle A2. In this case, each angle A1, A2 ranges from 30° to 60°. A1=45° and A2=40°.

[0123] The width of each first, second and third circumferential groove 62, 64, 66 is greater than or equal to 2 mm, preferably ranges from 5 mm to 15 mm and more preferably ranges from 7 mm to 12 mm and is here equal to 9.7 mm, 8.7 mm respectively. and 9.7 mm. The width of each transverse groove 72 is greater than or equal to 2 mm, preferably ranging from 5 mm to 15 mm and more preferably ranging from 7 mm to 12 mm and is here equal to 9.6 mm. The width of each oblique groove 68, 70 is greater than or equal to 2 mm, preferably ranging from 5 mm to 15 mm and more preferably ranging from 7 mm to 12 mm and is here equal to 10 mm.

[0124] The surface notch rate of the tread 14 associated with the grooves having a width greater than or equal to 2 mm, preferably 4 mm, here associated with the circumferential grooves 62, 64, 66, the transverse grooves 72 and the oblique grooves 68, 70 ranges from 35% to 55%, preferably from 40% to 50% and is here equal to 44%. The volume notch rate of the tread associated with the grooves having a width greater than or equal to 2 mm, preferably 4 mm, here associated with the circumferential grooves 62, 64, 66, the transverse grooves 72 and the oblique grooves 68, 70 ranges from 30% to 45%, preferably from 35% to 45% and is here equal to 39%.

[0125] The tread height is greater than or equal to 7 mm, preferably ranging from 9 mm to 16 mm and here is equal to 12 mm.

[0126] With reference to Figure 3, a pair 100 of first and second tires 10, 10' is shown, both in accordance with the invention. The tread 14 of the first tire 10 is symmetrical to the tread 14' of the second tire 10' with respect to a plane of symmetry S substantially perpendicular to an axis of rotation R common to the first and second tires 10, 10'. In the example of Figure 3, the first tire 10 is intended to be mounted on the right side of a vehicle while the second tire 10' is intended to be mounted on the left side of a vehicle so that the inner side INT of each first and second tire 10, 10' faces the wheel arch of the vehicle and so that the side EXT of each first and second tire 10, 10' is entirely visible from outside the vehicle when the tire is mounted on the vehicle.

[0127] With reference to FIG. 2, each bread 20 of the tread 14 comprises a single incision 80. Each bread 20 of each first and second circumferential column 22, 24 and of the additional circumferential column 30 comprises a so-called elongated incision 82 and here a single elongated incision 82.

[0128] We will now describe in detail with reference to figures 4 and 5 a loaf 20 of the second circumferential column 24 of loaves and the elongated incision 82 which is made therein.

[0129] With reference to figure 4, each bread 20 of the second circumferential column 24 is slender in the circumferential direction X. Indeed, each bread 20 of the second circumferential column 24 is inscribed in a rectangle RE of which two sides are parallel to the axial direction Y and two other sides of which are parallel to the circumferential direction X. The two sides parallel to the axial direction Y being smaller than the two sides parallel to the circumferential direction X, each bread 20 of the second circumferential column 24 is slender in the circumferential direction X. The slenderness line LE of each bread 20 of the second circumferential column 24 is the curved line joining the two leading edges 202 and trailing edges 204 and equidistant from the lateral edges 206, 208 joining the leading edges 202 and trailing edges 204. The average slenderness direction Ep is the straight line passing through the points of intersection between the curved slenderness line and the two leading edges 202 and trailing edges 204 which it crosses.

[0130] The circumferential length of each bread 20 of the second circumferential column 24, that is to say here the length of the two sides of the rectangle RE parallel to the circumferential direction X is equal to 40 mm. The width of each bread 20 of the second circumferential column 24, that is to say here the length of the two sides of the rectangle RE parallel to the axial direction Y is equal to 22 mm.

[0131] Each elongated incision 82 has a depth greater than or equal to 9 mm, preferably ranging from 10 to 14 mm and here equal to 12 mm. This depth is greater than or equal to 50%, preferably 70% and more preferably 90% of the height of the bread 20 in which said elongated incision 82 is made. Here, the height of each bread 20 of the second circumferential column 24 is substantially equal to 12 mm. Each elongated incision 82 has a width less than or equal to 2.0 mm, preferably ranging from 0.5 mm to 2.0 mm and here equal to 1.0 mm.

[0132] Each elongated incision 82 comprises a central portion 84 and first and second elongation portions 86, 88, each first and second elongation portion 86, 88 being in communication with the central portion 84. Each elongated incision 82 also comprises first and second blind ends 90, 92 as well as first and second dimensioning points 94, 96 arranged so as to define, on the one hand, the central portion 84 arranged between the first and second dimensioning points 94, 96 and, on the other hand, each first and second elongation portion 86, 88 arranged respectively between each first and second dimensioning point 94, 96 and each first and second blind end 90, 92. Each first and second dimensioning point 94, 96 is respectively distinct from each first and second blind end 90, 92.

[0133] The curvilinear length of each first and second elongation portion 86, 88, i.e. the curvilinear length between each first and second dimensioning point 94, 96 and respectively each first and second blind end 90, 92, is here equal to 8 mm. The curvilinear length of the central portion 84, i.e. i.e. the curvilinear length between each first and second dimensioning point 94, 96, is here equal to 30 mm. Thus, the ratio between the curvilinear length of each first and second elongation portion 86, 88 and the curvilinear length of the central portion 84 is strictly less than 1.0, preferably less than or equal to 0.7, preferably 0.5 and greater than or equal to 0.1, preferably 0.2 and more preferably ranges from 0.2 to 0.5 and here equal to 0.27.

[0134] With reference to FIG. 5, the first and second dimensioning points 94, 96 define a slenderness direction Ei of the elongated incision 82 and a maximum dimension Lmax of the elongated incision 82 according to the slenderness direction Ei of the elongated incision 82 and a maximum dimension lmax of the elongated incision 82 according to a direction Epi perpendicular to the slenderness direction Ei. In general, it is noted that the slenderness direction Ei of the elongated incision 82 coincides with the slenderness direction of the central portion 84. Each first and second elongation portion 86, 88 extends according to an elongation direction Ea1, Ea2. Here Lmax=31 mm, lmax=10 mm so that the elongated incision 82 has a slenderness greater than or equal to 1.5, preferably 1.7 and more preferably 2.0 and here equal to 3.1.

[0135] Each elongation direction Ea1, Ea2 of each first and second elongation portion 86, 88 and the slenderness direction Ei of the elongated incision 82 form an angle less than or equal to 80°, preferably ranging from 30° to 70°, more preferably ranging from 30° to 50° and here equal to 37°.

[0136] With reference to figure 6, the average slenderness direction Ep of the bread 20 and the slenderness direction Ei of the elongated incision 82 form an angle less than or equal to 45°, preferably 30°, more preferably 15° and even more preferably 5°.

[0137] With reference to Figure 7, the distance Li between the first and second dimensioning points 94, 96 of the elongated incision 82 along the average slenderness direction Ep of the bread 20 is here equal to 31 mm and the distance Lp between the first and second dimensioning points 98, 100 of the bread 20 along the average slenderness direction Ep of the bread 20 is here equal to 41 mm. The ratio between Li and Lp is greater than or equal to 0.5, preferably 0.7 and here equal to 0.76.

[0138] With reference to FIG. 8, the elongated incision 82 has first and second dimensioning points of the elongated incision 82 in a direction Epp perpendicular to the average slenderness direction Ep of the bread 20. Here, each first and second dimensioning point of the elongated incision 82 in the direction Epp coincides respectively with each first and second blind end 90, 92. The distance li between the first and second dimensioning points 90, 92 of the incision elongated 82 in the Epp direction is equal to 11 mm. The bread 20 has first and second points 102, 104 for sizing the bread 20 in the Epp direction. The distance Ip between the first and second points 102, 104 for sizing the bread 20 in the Epp direction is equal to 22 mm. The ratio between li and Ip is greater than or equal to 0.3, preferably 0.5 and here equal to 0.5.

[0139] Referring to Figure 5, the central portion 84 and each first and second elongation portion 86, 88 are arranged such that, when moving along the elongated incision 82 from each first and second elongation portion 86, 88 towards the central portion 84, the direction of movement changes relative to the slenderness direction Ei of the elongated incision 82 when passing respectively through each first and second dimensioning point 94, 96 of the elongated incision 82.

[0140] The central portion 84 is arranged such that, when moving along the elongated incision 82 in the central portion 84 from the first dimensioning point 94 to the second dimensioning point 96, the direction of movement does not change relative to the slenderness direction Ei of the elongated incision 82.

[0141] The first elongation portion 86 is arranged such that, when moving along the elongated incision 82 in the first elongation portion 86 from the first dimensioning point 94 to the first blind end 90, the direction of movement does not change relative to the slenderness direction Ei. Similarly, the second elongation portion 88 is arranged such that, when moving along the elongated incision 82 in the second elongation portion 88 from the second dimensioning point 96 defining the slenderness direction Ei to the second blind end 92, the direction of movement does not change relative to the slenderness direction Ei.

[0142] Returning to Figure 2, it will be noted that at least 20%, preferably at least 30% and here 50% of the number of loaves of the tread comprise an elongated incision 82, in this case the loaves 20 of the circumferential columns 22, 24 and 30. At least 50%, preferably 75% of the number of loaves having a circumferential slenderness, that is to say here at least 50%, preferably 75% of the number of loaves 20 of the circumferential columns 22, 24, 30 and 32 comprise an elongated incision 82.

[0143] Figures 9 to 12 show loaves comprising elongated incisions 82 according to other embodiments.

[0144] Unlike the elongated incisions 82 described with reference to the preceding figures, the elongated incisions 82 of figures 9 and 10 are such that the central portion 84 is not rectilinear. However, as for the elongated incisions 82 described with reference to the preceding figures, when moving along the elongated incision 82 in the central portion 84 from the first dimensioning point 94 defining the slenderness direction Ei to the second dimensioning point 96, the direction of movement does not change relative to the slenderness direction Ei.

[0145] Unlike the elongated incisions 82 described with reference to the preceding figures, the first and second elongated portions 86, 88 are curved in the same direction.

[0146] Unlike the elongated incisions 82 described with reference to the preceding figures, the elongated incision 82 of figure 12 comprises a single elongation portion 86.

[0147] The invention is not limited to the embodiments previously described.

Claims

CLAIMS 1. A tire (10) having an inner side (INT) and an outer side (EXT) imposed when the tire is mounted on a vehicle, the tire comprising a tread (14) comprising first and second axial edges (16A, 16B) arranged respectively on the inner and outer sides, the tread (14) comprising a plurality of loaves (20) and a plurality of grooves (62, 64, 66, 68, 70, 72) comprising: at least first, second and third circumferential grooves (62, 64, 66) arranged such that there is at least one first, second and third substantially circumferential line (63, 65, 67) passing respectively in each first, second and third circumferential groove (62, 64, 66) extending continuously over a circumference of the tire without cutting any loaf (20) of the plurality of loaves (20), each first, second, third line substantially circumferential (63, 65,67) having an axial width (Le) greater than or equal to 2 mm, each first, second and third circumferential groove (62, 64, 66) being arranged in an axial portion of axial width (P) equal to at most 75% of the axial width (L) of the tread (14) and extending from the first axial edge (16A), at least of the first, second, third circumferential columns (22, 24, 28) of loaves (20) of the plurality of loaves (20), transverse grooves (72) extending continuously from the first axial edge (16A) to the second axial edge (16B) of the tread (14) substantially parallel to each other, each transverse groove (72) intersecting each first, second and third circumferential groove (62, 64, 66), at least one additional circumferential column (30, 32) of loaves (20) of the plurality of loaves (20), the or each additional circumferential column (30,32) being the circumferential column axially closest to the second axial edge (16B) among the first, second, third circumferential columns (22, 24, 28) of loaves and said additional circumferential column (30, 32), each loaf (20) of the plurality of loaves (20) comprising a leading edge (202), the leading edge (202) of each loaf of at least each first, second and third circumferential column (22, 24, 28) of loaves has a mean direction forming, with the circumferential direction (X) of the tire, an angle (D1, D2, D3) strictly greater than the angle (A1, A2) formed by the mean direction of the leading edge (202) of each loaf of, the or each additional circumferential column (30, 32) of breads with the circumferential direction (X) of the tire.

2. Tire (10) according to the preceding claim, each transverse groove extending axially in an axially variable main direction, the angle formed by the main direction of each transverse groove and the circumferential direction of the tire has: - a non-zero monotonic variation between the first and second axial edges of the tread, or - is constant over at least one axial portion between the first and second axial edges of the tread and a non-zero monotonic variation over at least one complementary axial portion between the first and second axial edges of the tread.

3. Tire (10) according to any one of the preceding claims, intended for use in rally competition and more preferably in rally competition at least on earthy and / or gravelly and / or muddy ground and very preferably in rally competition on earthy ground.

4. A tire (10) according to any preceding claim, wherein the first circumferential groove (62) is the circumferential groove among the first, second, third circumferential grooves (62, 64, 66) arranged axially closest to the first axial edge (16A), the third circumferential groove (66) is the circumferential groove among the first, second, third circumferential grooves (62, 64, 66) arranged axially closest to the second axial edge (16B), the second circumferential groove (64) is arranged axially between the first circumferential groove (62) and the third circumferential groove (66).

5. A tire (10) according to any preceding claim, wherein the first circumferential column of loaves (22) is the column of loaves among the first, second, third circumferential columns (22, 24, 28) of loaves arranged axially closest to the first axial edge (16A), the third circumferential column of loaves (28) is the column of loaves among the first, second, third circumferential columns (22, 24, 28) of loaves arranged axially closest to the second axial edge (16B), the second circumferential column (24) of loaves is arranged axially between the first circumferential column (22) and the third circumferential column (28).

6. Tire (10) according to any one of the preceding claims, wherein: each bread (20) of the first circumferential column (22) is axially delimited by the first circumferential groove (62) and the first axial edge (16A), each bread (20) of the second circumferential column (24) is axially delimited by the first and second circumferential grooves (62, 64), each bread (20) of the third circumferential column (28) is axially delimited at least in part by the third circumferential groove (66).

7. A tire (10) according to any one of the preceding claims, wherein the tread (14) comprises a fourth circumferential column (26) of loaves (20) of the plurality of loaves (20) arranged axially between the second and third circumferential columns (24, 28) of loaves, the leading edge (202) of each loaf of the fourth circumferential column (26) of loaves having a mean direction forming an angle (D4) strictly greater than the angle (A1, A2) formed by the mean direction of the leading edge (202) of each loaf of the or each additional circumferential column (30, 32) of loaves.

8. Tire (10) according to the preceding claim, in which each bread (20) of the fourth circumferential column (26) is axially delimited by the second and third circumferential grooves (64, 66).

9. A tire (10) according to any one of the preceding claims, wherein each loaf (20) of the or each additional circumferential column (30, 32) of loaves is delimited by at least one oblique groove (68, 70) intersecting at least two circumferentially consecutive transverse grooves (72) and being arranged so that there is no circumferential line extending continuously over a circumference of the tire passing through the or each oblique groove (68, 70) delimiting each loaf (20) of said additional circumferential column (30, 32) of loaves without intersecting the loaves of said additional circumferential column (30, 32) of loaves.

10. A tire (10) according to any one of the preceding claims, wherein the tread (14) comprises first and second additional circumferential columns (30, 32) of loaves of the plurality of loaves, each first and second additional circumferential column (30, 32) being axially closer to the second axial edge (16B) than the first, second, third circumferential columns (22, 24, 28) of loaves, the leading edge (202) of each loaf of at least each first, second and third circumferential column (22, 24, 28) of loaves has a mean direction forming an angle (D1, D2, D3) strictly greater than the angle (A1, A2) formed by the mean direction of the leading edge (202) of each loaf of each first and second additional circumferential column (30, 32) of loaves, each loaf (20) of the first additional circumferential column (30) of loaves being axially delimited by two oblique grooves (68, 70) crossing two circumferentially consecutive transverse grooves (72), each loaf (20) of the second additional circumferential column (32) of loaves being axially delimited by an oblique groove (70) crossing two circumferentially consecutive transverse grooves (72) and the second axial edge (16B), each loaf (20) of each first and second additional circumferential column (30, 32) of loaves being arranged so that there is no circumferential line extending continuously over a circumference of the tire passing through the or each oblique groove (68, 70) delimiting each loaf of each first and second additional circumferential column (30, 32) of loaves without cutting the loaves respectively of each first and second additional circumferential column (30, 32) of loaves.

11. A tire (10) according to any preceding claim, wherein each first and second circumferential column (22, 24) of bars comprises a single bar (20) between two circumferentially consecutive transverse grooves (72).

12. A tire (10) according to any one of the preceding claims, wherein the third circumferential column (28) of loaves comprises at least two loaves (20), preferably only two loaves (20), between two circumferentially consecutive transverse grooves (72).

13. A tire (10) according to any one of the preceding claims, wherein the leading edge (202) of at least a portion of the loaves of the third circumferential column (28) of loaves has a curvilinear length strictly greater than the curvilinear length of each lateral edge (206, 208) of said loaf.

14. Pair of a first and a second tire (10, 10'), each first and second tire (10, 10') being according to any one of the preceding claims, pair in which the tread (14) of the first tire (10) is symmetrical to the tread (14') of the second tire (10') with respect to a plane of symmetry (S) substantially perpendicular to an axis of rotation (R) common to the first and second tires (10, 10').

15. Use of a tire (10) having an inner side (INT) and an outer side (EXT) imposed when the tire is mounted on a vehicle, the tire comprising a tread (14) comprising first and second axial edges (16A, 16B) arranged respectively on the inner and outer sides, the tread (14) comprising a plurality of loaves (20) and a plurality of grooves (62, 64, 66, 68, 70, 72) comprising: at least first, second and third circumferential grooves (62, 64, 66) arranged such that there is at least one first, second and third substantially circumferential line (63, 65, 67) passing respectively in each first, second and third circumferential groove (62, 64, 66) extending continuously over a circumference of the tire without cutting a loaf (20) of the plurality of loaves (20), each first, second third substantially circumferential line (63, 65, 67) having an axial width (Le) greater than or equal to 2 mm, each first, second and third circumferential groove (62, 64, 66) being arranged in an axial portion of axial width (P) equal to at most 75% of the axial width (L) of the tread (14) and extending from the first axial edge (16A), at least first, second, third circumferential columns (22, 24, 28) of loaves (20) of the plurality of loaves (20),transverse grooves (72) extending continuously from the first axial edge (16A) to the second axial edge (16B) of the tread (14) substantially parallel to each other, each transverse groove (72) intersecting each first, second and third circumferential groove (62, 64, 66), at least one additional circumferential column (30, 32) of loaves (20) of the plurality of loaves (20), the or each additional circumferential column (30, 32) being the circumferential column axially closest to the second axial edge (16B) among the first, second, third circumferential columns (22, 24, 28) of loaves and said additional circumferential column (30, 32), each loaf (20) of the plurality of loaves (20) comprising a leading edge (202), the leading edge (202) of each loaf of at least each first, second and third circumferential column (22, 24, 28) of loaves has a mean direction forming,with the circumferential direction (X) of the tire, an angle (D1, D2, D3) strictly greater than the angle (A1, A2) formed by the average direction of the leading edge (202) of each block of the or each additional circumferential column (30, 32) of blocks with the circumferential direction (X) of the tire or of a pair of first and second tires (10, 10') according to the preceding claim in competition, preferably in rally competition and more preferably in rally competition at least on earthy and / or gravelly and / or muddy ground and very preferably in rally competition on earthy ground.,

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