Vehicle wheel tyre

Abstract

A tire (1) comprises a tread band (2), a tread surface (3) located radially outward of the tread band, and a plurality of blocks (5) formed on the tread band. Each block (5) is at least partially delimited by a groove (4) defining a side face (7) of the block joined to a tread surface portion (6) defined on the block in the region of an edge (8) of the block. According to the invention, a plurality of consecutive recesses (9) are defined on a portion of the edge (8), and in the region of at least two of these recesses (9), a respective block portion (10) is provided, which defines a projection, which projects from the lateral face (7) of the block towards the inside of the groove (4) and extends as far as the bottom (4b) of the groove (4).

Description

Technical Field

[0001] The present invention relates to a tyre for vehicle wheels, in particular to a winter tyre. Background Art

[0002] The tyre generally comprises a carcass structure shaped toroidally around an axis of rotation and comprising at least one carcass ply the end edges of which are engaged in respective annular anchoring structures, called bead cores.

[0003] In a radially external position with respect to the carcass structure, there is arranged a belt structure, which, in the case of a tyre for automobiles, comprises at least two radially superposed rubberised textile strips provided with reinforcing cords, generally made of metal, and arranged in each strip in a mutually parallel manner but crossed with respect to the cords of adjacent strips, preferably symmetrically with respect to the equatorial plane of the tyre.

[0004] Preferably, the belt structure also comprises a third layer of textile or metal cords arranged circumferentially (0 degrees) in a radially external position at least at the end of the underlying belt strip. In tyres of the tubeless type, there is also a radially internal layer called liner, which has an impermeable character in order to ensure the airtightness of the tyre itself.

[0005] In a radially outer position with respect to the belt structure, there is applied a tread band made of elastomeric material on which is defined a tread surface intended to come into contact with the road surface.

[0006] In order to ensure sufficient grip even on wet roads, the tread band of the tire is provided with grooves of various shapes and geometries, the main function of which is to drain away water present between the tire surface and the road surface during their mutual contact, thus preventing the hydrostatic pressure caused by the impact of water on the advancing tire from being able to cause the tire to be even partially lifted off the road surface and thus cause the vehicle to lose control (a phenomenon known as "hydroplaning").

[0007] The grooves formed in the circumferential direction also affect the directional characteristics and driving stability of the tire, which is related to the ability of the tire to withstand tangential stresses parallel to the rotation axis of the tire.

[0008] Grooves formed in the transverse direction affect the traction characteristics of the tire, that is to say its ability to transmit tangential stresses parallel to the direction of travel to the road surface, in particular during acceleration and braking steps of the motor vehicle.

[0009] The grooves usually define a plurality of blocks on the tread band, each of which comprises a radially outer surface intended to contact the road surface and thus forming part of the tread surface of the tyre. In the case of winter tyres, small indentations, called "sipes", are usually formed on the blocks of the tread band, extending from the tread surface of the tyre towards the interior of the blocks. The function of the sipes is to provide an additional grip element and to retain a certain amount of snow in the case of driving on snowy surfaces, thereby improving the grip on the road surface.

[0010] Each block is also at least partially delimited by one or more sides defined by the sidewalls of the grooves surrounding the sides. Each side is joined to the radially outer surface of the tire by a respective edge, which in turn may have a chamfer or a sharp edge.

[0011] Typically, the sides of the block extend parallel to the longitudinal direction of the grooves defining the sides, but in some cases, one or more sides of the block may have a non-linear profile formed by a series of protrusions and recesses and defining an edge having a zigzag extension.

[0012] An example of a winter tire provided with blocks shaped in this way is described in US 2003 / 0029537.

[0013] Another example of a winter tyre with blocks shaped in this way is described in EP 3375639. In fact, this latter document describes a winter tyre with a shoulder block, one of the sides of which has, in its axially internal portion, a series of protrusions and depressions defining a zigzag development of corresponding edges. On said side, in its axially external portion, a depression is also formed, the bottom of which is raised with respect to the bottom of the groove so as to form a step extending towards the axial end of the tread band. Summary of the invention

[0014] The term "circumferential" direction means a direction pointing substantially in the direction of rotation of the tyre or in any case a direction slightly inclined (at most about 5°) relative to the direction of rotation of the tyre.

[0015] The term "axial" direction means a direction substantially parallel to the axis of rotation of the tyre or a direction at most slightly inclined (at most about 5°) relative to the axis of rotation of the tyre. The axial direction is generally perpendicular to the circumferential direction.

[0016] The term "radial" direction means a direction which is substantially perpendicular to the axis of rotation of the tire or which is at most slightly inclined (at most about 5°) with respect to this direction and which extends through the axis of rotation of the tire. In other words, a radial direction belongs to a plane which is perpendicular to the axis of rotation of the tire and which intersects this axis of rotation.

[0017] In particular, it may be noted that when reference is made to a radial direction with respect to an element of the tread band, such as, for example, a groove, a block or a component thereof, this is to be understood as the radial direction extending through this element.

[0018] The term "equatorial plane" of the tire means the axial center plane perpendicular to the axis of rotation of the tire.

[0019] The term "shoulder regions" of the tread band refers to portions of the tread band extending circumferentially in an axially external position with respect to the tread band itself. Preferably, each shoulder region extends over a width equal to at least 10% of the width of the tread band.

[0020] The term "groove" means a depression formed in the tread band portion, the width of which is greater than or equal to 1.5 mm and, preferably, the depth of which is greater than 3 mm.

[0021] The term "sipe" means a depression formed in a tread band portion, the width of which is less than 1.5 mm, preferably less than or equal to 1 mm.

[0022] The term "block" refers to that tread band portion which is delimited by at least one groove, preferably by at least two distinct grooves, and on which is defined, on its radially external surface, a tread surface portion intended to contact the road surface.

[0023] Thus, both a tread band portion having a closed outline defined by three or more grooves and a circumferential rib defined by a pair of grooves extending circumferentially around the tread band are considered to be blocks.

[0024] A "central block" is defined as a block not bounded by the axial ends of the tread band, whereas a block partially bounded by one of the axial ends of the tread band is defined as a "shoulder block".

[0025] The term "side" of a block refers to the surface that extends generally from the bottom of the grooves that delimit the block toward the tread surface portion of the block.

[0026] The term "inclination" of the lateral surface refers to the direction of maximum inclination of the lateral surface joining the bottom of the groove to the tread band portion of the block. This inclination may coincide with the radial direction or may be inclined relative to the radial direction, for example at an angle between 0° and 40° relative to the radial direction, depending on the functional characteristics of the groove.

[0027] The term "edge" of a block refers to the area of ​​the block joining the side of the block with the tread surface portion of the block. Thus, when the block is completely delimited by grooves, the edge defines the peripheral contour of the tread band portion of the block.

[0028] If the wall directly intersects the tread surface portion, the edge or a portion thereof may be formed by a sharp edge, or the edge or a portion thereof may be formed by a connecting surface connecting the wall to the tread surface portion.

[0029] The term "recess" of an edge refers to an edge portion in which the distance to the longitudinal axis of the groove it faces has a relative maximum. Typically, the recess is thus formed by a non-rectilinear edge portion having a concavity directed towards the groove.

[0030] The edge can have a straight or curved shape or a shape in the form of a broken line, in particular in the form of a zigzag. In the last case, it is also called "serrated".

[0031] The term "buttress" refers to a block portion that defines a raised portion that projects from the side of the block toward the interior of the groove it faces and extends to rest on the bottom of the groove. The buttress is therefore in relief relative to the side of the block and the bottom of the groove.

[0032] A tread band element, such as, for example, a block or part thereof, may be viewed in a "top plan view" when viewed from the outside of the tread band in a radial direction of the tread band extending therethrough.

[0033] Two or more edge portions have "substantially equal" lengths when their respective lengths differ from each other by at most 10% of the maximum length.

[0034] Two or more directions or two or more elements extending along respective directions (eg two edge portions) are "substantially parallel" when they are inclined relative to each other at an angle of less than 10°, preferably less than 5°.

[0035] The overall construction of the tread band, defined by the combination of grooves and blocks, constitutes the tread pattern of the tire.

[0036] The tread pattern may be of the “directional” type, that is to say configured to be mounted on a vehicle so that the tire rotates in a preferred direction of travel.

[0037] This defines a preferred rolling direction on the tread band, relative to which two elements of the tread band (such as, for example, the two edges of a block) can be identified as a "front" edge and a "rear" edge, respectively, the front element coming into contact with the road surface before the rear element when rolling along the preferred direction of travel.

[0038] The Applicant has initially observed that the rigidity of a block (understood as resistance to deformation under the effect of tangential stresses) is a parameter of particular relevance in determining the behaviour of a tyre on the road.

[0039] In particular, the Applicant has established that the greater the rigidity of the blocks, the greater the grip of the tyre generally.

[0040] In fact, during braking, acceleration or cornering, the block is subjected to tangential stresses which, if it lacks sufficient rigidity, could cause its associated deformation and local lifting of the block from the road surface, resulting in a reduction in the contact area between the block and the road surface and, therefore, also in a reduction in the friction force that the tyre normally applies to the road surface.

[0041] The Applicant has also observed that the rigidity of the blocks can be significantly reduced when sipes are formed on them, which, as mentioned above, are widely used in the case of winter tyres in order to improve the behaviour of the tyre on snowy surfaces.

[0042] The Applicant has also observed that, in particular in winter tyres, one or more sides of a block may have a continuous series of raised and depressed portions extending from the bottom of the groove to the corresponding edge of the block along a direction substantially parallel to the direction of maximum inclination of the side of the block relative to the groove.

[0043] The series of continuous projections and depressions defines a zigzag profile or a "sawtooth" profile on the respective edge, in which a plurality of continuous depressions are defined.

[0044] This particular configuration of the side effectively provides the blocks with new and additional gripping edges, thus improving the performance level of the tyre on snowy surfaces. Not only that, this configuration of the side allows a greater amount of snow to be retained, and also allows it to be retained in a more effective way, with respect to a side with a substantially "flat" profile, defining edges substantially parallel to the direction of extension of the grooves. This allows the tyre's grip on snowy roads to be further improved.

[0045] However, the Applicant has demonstrated that such a structure, by providing a series of continuous depressions, can actually reduce the volume and mass of the block, weakening its structure and thus further reducing its resistance to tangential stresses.

[0046] The Applicant has therefore perceived the need to provide a tyre having blocks which, despite having one or more sides with edges having a zigzag profile, have good rigidity and can therefore offer an increased level of performance on dry or wet roads.

[0047] In seeking to meet this requirement, the Applicant has observed that when the side of the block is subjected to tangential deformation, the direction of maximum deformation of the side of the block is that directed towards the inside of the groove it faces.

[0048] Therefore, the applicant believes that the structure of the block can be reconfigured in such a way that in the region of a plurality of continuous depressions formed on its side, an element capable of resisting deformation of the side of the block in at least one direction directed towards the inside of the groove can be provided.

[0049] Finally, the Applicant has discovered that defining a plurality of continuous depressions on the edge of the block and providing in the region of at least two of these depressions corresponding buttresses, i.e. portions of the block defining raised portions which project from the sides of the block towards the interior of the groove and which extend as far as the bottom of the groove, allows obtaining a block which, on the one hand, maintains the ability to effectively retain snow and, on the other hand, provides greater rigidity.

[0050] In particular, in a first aspect thereof, the invention relates to a tyre for vehicle wheels, said tyre comprising a tread band and a tread surface radially external to said tread band.

[0051] Preferably, a plurality of blocks are formed on said tread band.

[0052] Preferably, each block of the plurality of blocks is at least partially bounded by a groove, the groove defining a side of the block.

[0053] Preferably, a tread surface portion is defined on the block, the tread surface portion being delimited by an edge of the block, the edge joining the tread surface portion to the side of the block.

[0054] Preferably, a plurality of continuous recessed portions are defined on a portion of the edge.

[0055] Preferably, in the region of at least two of the plurality of recesses, respective buttresses are provided, ie respective block parts defining raised portions which protrude from the side faces of the block towards the inside of the groove and extend up to the bottom of the groove.

[0056] The Applicant considers that the provision of buttresses allows increasing the rigidity of the block, which is in fact supported laterally in the region of its sides so as to resist deformations of the block towards the inside of the groove it faces.

[0057] Furthermore, the precise arrangement of the buttresses in the region of the series of consecutive dimples allows a substantial gripping edge and a high snow retention capacity to be maintained, thus giving the tyre an optimal behaviour on snowy roads.

[0058] In the above aspects, the present invention may have at least one of the additional preferred features indicated below.

[0059] In some embodiments, each recessed portion of the plurality of recessed portions is defined by a first edge portion and a second edge portion, the second edge portion being continuous with the first edge portion and inclined relative to the first edge portion.

[0060] In some embodiments, the first edge portions of the recessed portions are substantially parallel to each other.

[0061] In some embodiments, the second edge portions of the recessed portions are substantially parallel to each other.

[0062] In some embodiments, the first edge portions of the recesses have substantially equal lengths.

[0063] In some embodiments, the second edge portions of the recessed portions have substantially equal lengths.

[0064] In this way, the first edge portion and the second edge portion substantially define a zigzag-shaped stretch of the edge portion.

[0065] Preferably, the first edge portion is longer than the second edge portion, more preferably at least 3 times longer.

[0066] In some embodiments, for each of the recessed portions, the first edge portion is inclined relative to the second edge portion at an angle between 70° and 110°, preferably about 79°.

[0067] In some embodiments, the first edge portion is inclined at an angle between 10° and 30°, more preferably about 15°, relative to the extending direction of the groove.

[0068] In some embodiments, the second edge portion is inclined at an angle between 60° and 90°, more preferably about 75°, relative to the extending direction of the groove.

[0069] In some embodiments, the plurality of recesses includes at least four recesses.

[0070] Preferably, the recessed portions of the plurality of recessed portions are substantially identical to each other.

[0071] In some embodiments, each buttress portion extends along a longitudinal direction that is inclined relative to an extension direction of the groove when viewed from a top plan view.

[0072] Preferably, the longitudinal direction is inclined at an angle between 10° and 30°, more preferably about 15°, relative to the extension direction of the groove.

[0073] In some embodiments, the buttress portions extend along respective longitudinal directions that are substantially parallel to each other.

[0074] In some embodiments, the longitudinal direction along which the buttress portion extends intersects one of the second edge portions when viewed from a top plan view.

[0075] In other words, each buttress portion extends from a portion of the side of the block, the portion being defined in a position below one of the second edge portions.

[0076] In some embodiments, the longitudinal direction along which the buttress portion extends is substantially parallel to the first edge portion when viewed from a top plan view.

[0077] In particular, each buttress portion extends from a side portion corresponding to the second edge portion in the region of a respective recess of the edge in a longitudinal direction parallel to the first edge portion, wherein the recess is defined by the first edge portion and the second edge portion.

[0078] Preferably, each buttress portion abuts against the side surface of the block in the region of the first edge portion.

[0079] In particular, each buttress portion extends from a portion of the side of the block defined in a position below one of the second edge portions, held against a side portion defined in a position below the first edge portion.

[0080] In some embodiments, each buttress portion defines a step-like structure comprising at least one side wall directed towards the inside of said groove and an upper wall directed radially towards the outside of the tread band.

[0081] Preferably, the upper wall and the side walls of the buttress portion form sharp edges.

[0082] In this way, additional gripping edges are provided on the blocks, which may be advantageous in the event of driving on snowy roads.

[0083] In some embodiments, the upper wall is joined to the side face of the block in the region of the second edge portion at a distance of at least 2 mm from the second edge portion.

[0084] In other words, the buttress portion extends from the bottom of the groove up to the side of the block, but is maintained in a lowered position relative to the second edge portion. In this way, the buttress portion can perform its supporting function for the block in the lower part of the side, while the upper part of the side remains free to perform its function of retaining snow and having a gripping edge defined by the first edge portion and the second edge portion.

[0085] Preferably, the upper wall is joined to the side face of the block in the region of the second edge portion at a fraction of the distance from the second edge portion equal to between 30% and 80% of the depth of the groove.

[0086] Preferably, the upper wall is substantially planar and continuous.

[0087] In some embodiments, the upper wall is inclined relative to the tread surface portion of the block at an angle between 20° and 60°, more preferably between 30° and 45°.

[0088] In other words, the upper wall is in the form of an inclined slope which extends continuously from the bottom of the groove to the side of the block.

[0089] In this way, the buttress portion acts as a support for the side of the block in the region of the second edge portion.Such a configuration of the buttress portion has been found to be particularly effective in resisting any deformation of the block in the longitudinal direction of the buttress portion.

[0090] In some embodiments, said buttress portion is oriented so that said upper wall faces away from the equatorial plane of said tread band.

[0091] In this way, the buttresses are found to be particularly effective in resisting any deformation of the block caused by tangential stresses having an axial orientation directed towards the outside of the tread band. This is found to be particularly effective in increasing the rigidity of the block during cornering, particularly when the block is positioned in the shoulder region of the tread band.

[0092] Preferably, the upper wall has a width substantially equal to the extent of the second edge portion.

[0093] In some embodiments, said side faces of a block have, at least in the region of said first edge portion and said second edge portion, the same inclination relative to a radial direction of said tread band extending across said side faces.

[0094] Preferably, said side faces of the block are inclined with respect to said radial direction at an angle between 0° and 20°, more preferably about 10°.

[0095] In some embodiments, the inclination of said sidewall of said buttress portion relative to a radial direction of said tread band extending across said side surface is substantially the same as the inclination of said side surface.

[0096] Preferably, the side walls of the buttress portion are substantially parallel to the side faces of the block in the region of the first edge portion.

[0097] In some embodiments, said extension direction of said grooves is inclined at an angle comprised between 60° and 90° with respect to a circumferential direction defined on said tread band.

[0098] Therefore, the edge of the block having the plurality of recessed portions formed thereon preferably extends in a direction having a major axial component, thereby being able to be used in a more effective manner.

[0099] In some embodiments, said plurality of blocks are positioned in a shoulder region defined on said tread band.

[0100] Preferably, said plurality of blocks are formed by shoulder blocks.

[0101] In some embodiments, a tread pattern of a directional type is defined on said tread band, said tread pattern of the directional type providing a preferred rolling direction of said tyre.

[0102] Preferably, said plurality of depressions are formed on a rear edge of said block relative to said preferred rolling direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] The characteristics and advantages of the invention will be better understood from the detailed description of some preferred embodiments of the invention illustrated by way of non-limiting example with reference to the accompanying drawings, in which:

[0104] - Figure 1 is a schematic plan view of a tread band portion of a tyre for a vehicle wheel constructed in accordance with the present invention,

[0105] - Figure 2 Drawn to an enlarged scale Figure 1 A schematic perspective view of a block of a tread band of a tire,

[0106] - Figure 3 yes Figure 2 Schematic plan view of a portion of a block. DETAILED DESCRIPTION

[0107] With reference to the accompanying drawings, 1 generally indicates a tyre for vehicle wheels constructed in accordance with the present invention.

[0108] The tyre 1 has a general substantially toroidal shape extending around an axis of rotation defining an axial direction Y of the tyre and which is crossed by an equatorial plane perpendicular to the axis of rotation, said equatorial plane defining a circumferential direction X.

[0109] The tyre 1 comprises a tread band 2 on which a tread surface is defined, arranged in a radially outer position relative to the tread band 2 and intended to come into contact with a road surface.

[0110] The tire 1 has a nominal section width of, for example, about 205 mm and a rim diameter of 16 inches.

[0111] The tread band 2 is still defined with: a central area, which extends circumferentially and symmetrically around the equatorial plane of the tire; and a pair of shoulder areas, which extend at axially opposite sides of the central area to corresponding axial ends 3 of the tread band 2 in axially outer positions relative to the tread band 2.

[0112] Formed on the tread band 2 are a plurality of first grooves 4 and a plurality of second grooves 4 a which substantially delimit a respective plurality of blocks formed on the tread band 2 .

[0113] The first grooves 4 extend transversely relative to the tread band 2 from the axial end 3 and through the shoulder region along a curvilinear direction of extension A towards the equatorial plane of the tyre.

[0114] The first grooves 4 are substantially parallel to each other and have a depth between 7 mm and 9 mm (eg, about 8.5 mm) and a width between 4 mm and 9.5 mm.

[0115] The second grooves 4 a extend such that pairs of the first grooves 4 arranged one after another along the circumferential direction X are connected to each other.

[0116] The second grooves 4a are substantially rectilinear and inclined at about 15° with respect to the circumferential direction X and have a depth between 3 and 5 mm and a width between 2.5 and 4 mm.

[0117] The extension direction A of the first groove 4 is inclined at an angle of about 70° with respect to the circumferential direction X in an axially outer portion thereof close to the axial end 3 .

[0118] The arrangement of blocks and grooves generally defines the tread pattern of the tire 1 and, in the preferred embodiment described herein, defines a directional type of tire in which a preferred rolling direction of the tire is defined. Figure 1 Marked as F in the middle.

[0119] The blocks formed on the tread band 2 may differ in central blocks 5a, which are generally delimited by grooves, and in shoulder blocks 5, which are delimited in the region of their sides by axial ends 3.

[0120] The shoulder block 5 is thus defined by the axial end 3 , a pair of first grooves 4 and a second groove 4 a connecting the two aforementioned grooves 4 .

[0121] The shoulder block 5 comprises: a tread surface portion 6 defined on a radially outer surface of the shoulder block and intended to come into contact with the road surface; and a plurality of side faces 7 extending towards the tread surface portion 6 from respective bottoms 4b, 4c of the grooves 4 and 4a defining the shoulder block 5.

[0122] The tread surface portion 6 is also formed with sipes 6a which are formed in various ways and configured to improve the behavior of the tire 1 on snowy roads.

[0123] Each side surface 7 extends from the bottom 4b of the first groove 4 or the bottom 4c of the second groove 4a toward the tread surface portion 6 at a substantially constant inclination, wherein the inclination diverges slightly relative to the radial direction of the tire, and the angle formed by the inclination with the radial direction of the tire is between about 2° and about 20°, for example, about 5°, about 10° or about 15°.

[0124] Each side face 7 is joined to the tread surface portion 6 in the region of a respective edge 8 a of the shoulder block 5 .

[0125] In particular, with reference to the preferred rolling direction F, a rear edge 8 is identified on the shoulder block 5 .

[0126] The side faces 7 of the shoulder blocks 5 extending from the rear edge 8 are formed such that the rear edge 8 has a plurality of continuous depressions which are all referenced 9 and which substantially define the zigzag-shaped development of the rear edge 8 .

[0127] The depressions 9 are substantially identical to one another and, in the preferred embodiment described here, there are four or six depressions, depending on the length of the shoulder blocks 5 on which they are formed.

[0128] Each recessed portion 9 is defined by a first edge portion 9a and a second edge portion 9b which is continuous with the first edge portion 9a and inclined at an angle, for example, about 79°, relative to the first edge portion 9a.

[0129] Each first edge portion 9a is substantially straight and inclined at an angle of about 15° with respect to the extension direction A of the first groove 4 it faces.

[0130] Each first edge portion 9 a is about 4 mm long, and is about four times longer than the second edge portion 9 b forming the recessed portion 9 together therewith.

[0131] The first edge portions 9a of the recessed portions 9 are further substantially parallel to each other.

[0132] Similarly, each second edge portion 9b is substantially straight and inclined at an angle of about 75° with respect to the extending direction A of the first groove 4 it faces. Furthermore, the second edge portions 9b are substantially parallel to each other.

[0133] The shoulder block 5 also comprises, in the region of each depression 9 defined on the rear edge 8 , a respective buttress 10 , ie a block portion defining a protrusion projecting from the side 7 towards the inside of the first groove 4 and extending as far as the bottom 4 b of the first groove 4 .

[0134] In the preferred embodiment described herein, the buttress portions 10 are identical to each other, but different structures may be used according to production needs or other functional requirements.

[0135] Each buttress portion 10 defines a step-like structure starting from the portion of the side surface 7 located below the second edge portion 9b, continuing by being held against the side surface 7 in the region of the first edge portion 9a until connecting to the bottom 4b of the first groove 4. The length of the buttress portion 10 is substantially equal to the length of the first edge portion 9a when viewed from a top plan view.

[0136] In this way, the buttress portion 10 extends in a main longitudinal direction B which is substantially parallel to the first edge portion 9 a and which is inclined at an angle of about 15° with respect to the extension direction A of the first groove 4 .

[0137] The longitudinal directions B of the different buttress portions 10 formed on the shoulder blocks 5 are substantially parallel to each other.

[0138] On each buttress portion 10, a side wall 11 is defined, directed towards the inside of the first groove 4, and an upper wall 12 directed radially towards the outside of the tread band 2 and joined to the side wall 11 by a sharp edge 13. The upper wall 12 is substantially planar and extends continuously from the side 7 up to the bottom 4b, with an inclination of about 45° relative to the tread surface portion 6.

[0139] The width of the upper wall 12 is substantially equal to the elongation of the second edge portion 9b.

[0140] In the region of the second edge portion 9 b , the upper wall 12 joins to the side face 7 at a distance of approximately 5 mm from the second edge portion 9 b , said distance being equal to approximately 60% of the depth of the first groove 4 .

[0141] The upper wall 12 thus defines a slope which rises from the bottom 4b of the first groove 4 and is supported laterally on the side portion 7 below the first edge portion 9a until it connects to the side portion 7 below the second edge portion 9b.

[0142] The side wall 11 of the buttress portion 10 joins the upper wall 12 to the bottom 4 b of the first groove 4 and has a substantially planar structure substantially parallel to the side surface 7 in the region of the first edge portion 9 a (in a portion not affected by the buttress portion 10 ).

[0143] The buttress portion 10 formed in this way is therefore oriented in such a way that the upper wall 12 is directed towards the axial end 3 of the tread band 2 situated on the side opposite to the equatorial plane.

[0144] In this way, the buttress portions 10 act as supporting elements for the flanks 7 , acting to counteract any deformation of the shoulder blocks 5 due to tangential stresses applied to the tread surface portion 6 and directed towards the outside of the tread band 2 .

[0145] This feature advantageously increases the rigidity of the shoulder blocks 5 , which results in improved behaviour on roads with a wet or dry surface, in terms of the performance level of the tyre 1 .

[0146] Furthermore, the provision of the buttress portions 10 and the dimples 9 which are lowered relative to the tread surface portion 6 allows the tire 1 to achieve an optimum performance level also on snowy roads.

[0147] Of course, in order to meet specific and accidental application requirements, those skilled in the art may apply additional modifications and variations to the above invention, which are still included in the protection scope defined by the appended claims.

[0148] For example, in a block, besides the edge provided with the recess and the corresponding supporting buttress portion, this may not be limited to the rear edge, but instead may be provided in one or more of the different edges of the block.

[0149] Furthermore, the provision of edges provided with depressions and respective supporting buttresses may not be limited to shoulder blocks but, on the contrary, may be provided in any block or any type of block defined on the tread band.

[0150] Again, a buttress portion different from the above can be formed by appropriately changing its size and form according to specific functional requirements.

Claims

1. A tyre (1) comprising a tread band (2), a tread surface (3) situated radially outside said tread band, and a plurality of blocks (5) formed on said tread band, each block (5) being at least partially delimited by a groove (4), said groove defining a side (7) of said block, a tread surface portion (6) being defined on said block, said tread surface portion being delimited by an edge (8) of said block, said edge (8) connecting said tread surface portion (6) to said side (7) of said block, wherein: A plurality of continuous recesses (9) are defined on a portion of the edge (8), and in the region of at least two of the plurality of recesses (9), corresponding block portions (10) are provided, the block portions defining a raised portion, the raised portion protruding from the side surface (7) of the block toward the inner side of the groove (4) and extending to the bottom (4b) of the groove (4).

2. The tire according to claim 1, wherein: Each of the plurality of recessed portions (9) is defined by a first edge portion (9a) and a second edge portion (9b), the second edge portion being continuous with the first portion (9a) and inclined relative to the first edge portion (9a).

3. The tire according to claim 2, wherein: The first edge portion (9a) is longer than the second edge portion (9b).

4. A tyre according to any one of the preceding claims, wherein: The plurality of recessed portions include at least four recessed portions (9) that are substantially identical to each other.

5. A tyre according to any one of the preceding claims, wherein: In a top plan view, each of the block portions (10) extends along a longitudinal direction (B) that is inclined relative to an extension direction (A) of the groove (4).

6. A tyre according to any one of the preceding claims, wherein: The block portions (10) extend along respective longitudinal directions (B) which are substantially parallel to each other.

7. The tire according to claim 6, wherein: In a top plan view, the longitudinal direction (B) along which the block portion (10) extends intersects one of the second edge portions (9b).

8. The tire according to claim 6 or 7, wherein: In a top plan view, the longitudinal direction (B) along which the block portion (10) extends is substantially parallel to the first edge portion (9a).

9. A tyre according to any one of the preceding claims, wherein: Each block portion (10) defines a step-like structure comprising at least one side wall (11) directed towards the inside of the groove (4) and an upper wall (12) facing radially towards the outside of the tread band (2).

10. The tire according to claim 9, wherein: At a distance of at least 2 mm from the second edge portion (9b), the upper wall (12) is joined to the side face (7) of the block in the region of the second edge portion (9b).

11. The tire according to claim 9 or 10, wherein: The upper wall (12) is substantially planar and continuous.

12. The tire according to any one of claims 9 to 11, wherein: The upper wall (12) is inclined at an angle between 20° and 60° relative to the tread surface portion (6) of the block.

13. The tire according to any one of claims 9 to 12, wherein: The block portion (10) is oriented in such a way that the upper wall (12) faces away from the equatorial plane of the tread band (2).

14. The tire according to any one of claims 2 to 13, wherein: At least in the region of said first edge portion (9a) and said second edge portion (9b), said side faces (7) of said blocks have the same inclination relative to a radial direction of said tread band (2) extending through said side faces.

15. The tire according to any one of claims 9 to 14, wherein: The inclination of the side wall (11) of the block portion (10) relative to a radial direction of the tread band (2) extending through the side face (7) is substantially the same as the inclination of the side face (7) relative to the radial direction.

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