阅读说明：本技术 用于交通工具轮子的具有凹口抓地元件的轮胎 (Tyre for vehicle wheels with notched grip elements ) 是由 托马索·皮佐尔诺 于 2020-02-24 设计创作，主要内容包括：用于交通工具轮子的轮胎包括具有多个肋和/或块状物的胎面带；至少一个抓地元件(3)形成在所述肋(2)和/或块状物中的至少一个上,其中所述抓地元件(3)由凹口(4A)界定,该凹口具有至少部分曲线的闭合线的设计,并且包括一个或更多个胎面部分(5A),其中在凹口(4A)内有至少一个胎面部分(5A)相对于凹口(4A)的底部(43)凸起,并且与凹口(4A)的外轮廓(41)分离。(A tyre for vehicle wheels comprises a tread band having a plurality of ribs and/or blocks; at least one grip element (3) is formed on at least one of the ribs (2) and/or blocks, wherein the grip element (3) is delimited by a recess (4A) having an at least partially curvilinear closed line design and comprising one or more tread portions (5A), wherein within the recess (4A) there is at least one tread portion (5A) that is convex with respect to the bottom (43) of the recess (4A) and that is separated from the outer contour (41) of the recess (4A).)

1. Tyre (1) for vehicle wheels, comprising a tread band having a plurality of ribs (2) and/or blocks, wherein at least one grip element (3) is formed on at least one of said ribs (2) and/or blocks, wherein said grip element (3) is delimited by a recess (4A, 4B) having an extension of a closed line that is at least partially curvilinear, and comprises one or more tread portions (5A, 5B).

2. Tyre (1) according to claim 1, wherein said one or more tread portions (5A, 5B) are located within said recess (4A, 4B).

3. Tyre (1) according to claim 2, wherein said recess (4A, 4B) has an outer profile (41) and said at least one tread portion (5A) is separated from said outer profile (41).

4. Tyre (1) according to any one of the previous claims, wherein said closed line has a circular or elliptical or oval shape.

5. Tyre (1) according to any one of the previous claims, wherein said closing line has a lobed shape, in particular having a first and a second end lobe and an intermediate transition.

6. Tyre (1) according to any one of the previous claims, wherein said at least one tread portion (5A) has a cylindrical or truncated conical shape.

7. Tyre (1) according to any one of the previous claims, wherein said at least one tread portion (5A) has a profile corresponding to the shape of said closed line.

8. Tyre (1) according to any one of the previous claims, wherein said at least one tread portion (5A) has internally a hole (6) or a hollow.

9. Tyre (1) according to claim 8, wherein said hole (6) or hollow is deeper than the recess bottom (5A).

10. Tyre (1) according to claim 8 or 9, wherein said hole (6) has a first conical end region (6A) and a second truncated conical end region (6B), wherein said first end region (6A) and said second end region (6B) have different inclinations with respect to the axis of said hole (6), in particular the inclination of said first end region (6A) is smaller than the inclination of said second end region (6B).

11. Tyre (1) according to any one of the previous claims, wherein said grip element (3) comprises a plurality of tread portions (5A, 5B), in particular two or three or four tread portions (5A, 5B), adjacent to each other and located within said recess (4B).

12. Tyre (1) according to claim 11, wherein said plurality of tread portions (5A, 5B) define a profile and said profile corresponds to the shape of said closed line.

13. Tyre (1) according to claim 11 or 12, wherein said plurality of tread portions (5A, 5B) comprises two tread portions (5A) having a cylindrical or truncated conical shape.

14. Tyre (1) according to any one of the previous claims, wherein a first plurality of grip elements (3, 32) is formed on the first rib (2, 22).

15. Tyre (1) according to claim 14, wherein said first plurality of traction elements (3, 32) are identical to each other.

16. Tyre (1) according to claim 15, wherein said first plurality of grip elements (3, 32) have the same first direction.

17. Tyre (1) according to claim 14 or 15 or 16, wherein a second plurality of grip elements (3, 31, 33) is formed on the second rib (2, 21, 23).

18. Tyre (1) according to claim 17, wherein said second plurality of grip elements (3, 31, 33) are identical to each other.

19. Tyre (1) according to claim 18, wherein said second plurality of grip elements (3, 31) has the same second direction.

20. Tyre (1) according to claims 16 and 19, wherein said first direction of said first plurality of grip elements (3, 31) is different from said second direction of said second plurality of grip elements (3, 31).

Technical Field

The present invention relates to a tyre for vehicle wheels provided with notched grip elements.

In particular, the invention applies to tyres suitable for use on non-dry and/or poorly adhering roads, for example due to the presence of water, snow, ice or mud.

Preferably, the invention applies to tires for heavy vehicle wheels (cargo and/or personnel transport).

Heavy tires require a combination of features such as durability, low noise, driving comfort, reduced fuel consumption and grip on all roads.

Generally, different categories of tires are distinguished according to their intended use; for example, there are traction tires, directional tires, and non-traction tires.

Generally, traction tires have a design with blocks (blocks) and are mounted on drive shafts; the directional tire adopts a stripe design and is mainly arranged on a steering shaft; non-traction tires are primarily of a striped design, cannot be used on steering axles, and are primarily used on trailers.

Whatever the category to which a tire belongs, it is required that the tire can sufficiently grip: the traction tires are configured to transmit driving torque to the ground, the directional tires allow one to change the direction of travel of the vehicle and thus oppose centrifugal forces, and the braking non-traction tires transmit braking torque to the ground.

Generally, in some vehicles, traction tires may also be used for orientation. For example, a heavy vehicle for passenger transport may be equipped with a tire provided with an orientation design suitable for a steering shaft, which is also on the drive shaft. Generally, in situations where high traction is required, a chunky traction tire is used.

Tires with circumferential grooves are also commonly used for braking.

Generally, the tread design of a traction tire has circumferential grooves (more or less offset) that pass through lateral grooves, creating distinct areas of the tread known as "blocks".

On the other hand, in general, the tread of a non-traction tire is not provided with transverse grooves and therefore has a plurality of "ribs" separated by circumferential grooves.

The tread pattern (tread pattern) allows traction to be provided by the contact pressure on the ground by the edges of the blocks, which, like "claws", are close to the ground.

However, during rolling, the alternation between the mass (the contact area thereof) and the groove (the non-contact area) generates vibrations, which are transmitted to the air, generating noise.

In addition, vibrations propagate through the tire structure and through the suspension system to the steering wheel, thereby reducing driver comfort.

Therefore, traction tires have conflicting requirements: a large number of blocks is advantageous in order to provide good grip on the ground, while on the other hand the number of blocks should be as small as possible in order to provide high comfort and low noise.

Examples of tyres provided with recesses or openings made in the ribs and/or blocks are disclosed in documents EP2563604, FR2530194, WO 2016100032.

Summary of The Invention

The applicant has identified a construction of a grip element that combines the above requirements.

In general, the present invention relates to a tyre for vehicle wheels comprising a tread band having a plurality of ribs and/or blocks, wherein at least one grip element is formed on at least one of the ribs and/or blocks, wherein the grip element is defined by a recess having an extension of a closed line that is at least partially curvilinear, and comprises one or more tread portions.

Preferably, the closed line has a circular or elliptical or oval shape.

Preferably, the closed line has a lobed shape.

Preferably, the closing line defines a first end lobe and a second end lobe and an intermediate transition.

Preferably, the intermediate transition interconnects the first end lobe and the second end lobe.

Preferably, the tread portion is located within the recess.

Preferably, the tread portion is surrounded by a recess.

Preferably, the recess has an outer profile and the tread portion is separated from the outer profile of the recess.

Preferably, the traction elements comprise one or more tread portions located inside the recesses.

Preferably, the recess has an outer profile and the tread portion is separated from the outer profile of the recess.

Preferably, the tread portion has a cylindrical or truncated conical shape.

Preferably, the tread portion has a shape corresponding to the shape of said closed line.

Preferably, the tread portion has a hole or hollow on the inside.

Preferably, the hole or recess is deeper than the bottom of the recess.

Preferably, the orifice has a first end region which is conical and a second end region which is truncated conical.

Preferably, the first end region and the second end region have different inclinations with respect to the axis of the orifice.

Preferably, the inclination of the first end region is smaller than the inclination of the second end region.

Preferably, the first end region is located at a greater depth than the second end region. Preferably, the gripping element comprises a plurality of tread portions, in particular two or three or four tread portions, adjacent to each other and located within the recess.

Preferably, the plurality of tread portions define a profile, and the profile corresponds to the shape of a closed line.

Preferably, the plurality of tread portions includes two tread portions having a cylindrical or truncated conical shape.

Preferably, the first plurality of traction elements are formed on the first rib.

Preferably, the first plurality of traction elements are identical to each other.

Preferably, the first plurality of traction elements have the same first direction.

Preferably, the second plurality of traction elements are formed on the second rib.

Preferably, the second plurality of traction elements are identical to each other.

Preferably, the second plurality of traction elements have the same second direction.

Preferably, the first direction of the first plurality of traction elements is different from the second direction of the second plurality of traction elements.

The traction element may be positioned at different points of the tread and, preferably, it is positioned at a plurality of points of the same tire tread.

In particular, the grip elements may be positioned in the ribs or blocks.

Preferably, the grip element may be defined by a recess having an at least partially curvilinear closed line design and comprising one or more tread portions.

Preferably, within the recess, at least a portion of the tread surface is raised relative to the bottom of the recess and is spaced apart from the outer contour of the recess.

Preferably, the recess has a curved shape, the shape being a closed line, comprising circular or elliptical or rectilinear portions and/or combinations of said portions.

Preferably, the recesses have a lobed pattern.

Preferably, the recess has a first end lobe and a second end lobe connected by an intermediate transition.

Advantageously, the tread portion within the recess has a cylindrical or truncated conical shape.

The tread portion within the recess may have a shape corresponding to the shape of the closed line of the recess.

Advantageously, the tread portion inside the recess has a hole or hollow inside.

The hole or recess is preferably deeper than the bottom of the recess.

Preferably, the orifice has a first end region which is conical and a second end region which is truncated conical.

Preferably, the first end region and the second end region have different inclinations with respect to the axis of the orifice.

Preferably, the inclination of the first end region is smaller than the inclination of the second end region.

According to some second advantageous embodiments, a plurality of tread portions adjacent to one another, in particular two or three or four tread portions, are located within the recess. In this case, preferably, the plurality of tread portions define a profile corresponding to a closed line shape of the concave recess.

According to a particularly advantageous embodiment, the plurality of tread portions comprises two tread portions having a cylindrical or truncated conical shape.

The invention is particularly advantageous if the tread has circumferential grooves, wherein the traction is advantageously increased by using circular and/or lobed holes and recesses without transverse grooves.

Drawings

Further characteristics and advantages of the invention are explained below with reference to embodiments illustrated by way of non-limiting example in the accompanying drawings, in which:

figure 1 shows a perspective overall view of an exemplary embodiment of a tyre for vehicle wheels according to the present invention,

figure 2 shows an enlarged view of a portion of figure 1,

figure 3 shows a top view (figure 3A) and a cross-sectional view (figure 3B) of a first example of a traction element formed in the tyre of figure 1,

figure 4 shows a top view of a second example of a traction element formed in the tyre of figure 1,

figure 5 shows a top view (figure 5A) and a cross-sectional view (figure 5B) of a second example of a grip element with size indication,

fig. 6 to 13 show examples of tire treads according to the invention.

Detailed description of the invention

In fig. 1 and 2, an exemplary embodiment of a tyre 1 according to the present invention can be seen.

The tyre 1 comprises a tread band having a plurality of circumferential ribs 2.

In particular, but not in a limiting way, the tyre 1 comprises two ribs 21 on the edges of the belt, a rib 23 in the centre of the belt and two ribs 22 in an intermediate position between the ribs 21 and 23.

Between two adjacent ribs there is a circumferential groove, in particular an offset groove. Further, the center rib 23 has a center offset groove.

The exemplary embodiment of the tire according to the present invention, which replaces the tire of fig. 1 and 2, may have a different construction; in particular the different number of ribs and/or blocks.

As already mentioned, the core of the invention is the presence of at least one particular "grip element" on the tread, in particular on the ribs or blocks.

In general, there may be a plurality of traction elements in various arrangements and configurations.

For example, with reference to the tire 1 of the example of fig. 1 and 2, there are a plurality of grip elements 3.

On each rib 21 there is a plurality of grip elements 31, the grip elements 31 being arranged, for example, on the circumference of the tire.

On each rib 22 there is a plurality of grip elements 32, the grip elements 32 being arranged, for example, on the circumference of the tire.

On the rib 23, there are two pluralities of grip elements 33, for example arranged on two circumferences of the tyre on a first side and a second side offset from the groove.

According to the grip element of the invention, the tread surface occupied is preferably comprised between about 30mm²And about 1800mm²More preferably about 100mm²And about 600mm²According to a particular embodiment about 250mm²。

The traction elements may have a relatively large circumference, preferably, according to a specific embodiment of about 73mm, the circumference of one of these elements may be between about 10mm and about 450mm, more preferably between about 30mm and about 150mm, even more preferably between about 60mm and about 100 mm.

The grip element according to a tire embodiment of the invention is delimited by a recess having an extension of a closed line that is at least partially curvilinear and comprises one or more tread portions.

Within the recess, at least a portion of the tread surface is raised relative to the bottom of the recess and separated from the outer contour 41 of the recess.

Referring to the traction element 3A of fig. 3, there is a recess 4A and a tread portion 5A.

In fig. 3A, it can be seen that the recess 4A has an outer profile 41 and an inner profile 42, in the example of the figure the outer profile 41 and the inner profile 42 having the same shape (or they may have slightly different shapes). Furthermore, in fig. 3B it can be seen that the recess 4A (preferably but not necessarily with uniform depth) has a bottom 43 connected to the profiles 41 and 42 by walls, in the example of the figure both vertical (alternatively one or both may be inclined).

In fig. 3A and 3B, it can be seen that the tread portion 5A is convex with respect to the bottom 43 and is separated from the outer contour 41. As shown in fig. 3B, it is preferable that the projection of the tread portion 5A has its upper surface (i.e., the surface furthest from the tire axis) aligned with the tread surface surrounding the traction elements 3A.

With reference to the traction element 3B of fig. 4, there is a recess 4B and three tread portions, two of which are indicated by the reference numeral 5A and one of which is indicated by the reference numeral 5B.

For the grip element 3B of fig. 4, a similar design as previously with respect to the grip element 3A of fig. 3 is also applicable.

The three tread portions 5A, 5B, 5A are raised with respect to the bottom of the recess and are separated from the outer contour 46 of the recess 4B; preferably, but not necessarily, the projections of the three composite material portions have the same size; it is preferable, but not necessary, that the projections are such that the upper surface (i.e. the surface furthest from the axis of the tire) is aligned with the tread surface surrounding the traction elements 3B.

The two tread portions of fig. 4 are identical to the tread portion of fig. 3, and therefore the same reference numeral 5A is used.

It should be noted that the particular configuration of fig. 4 is symmetrical with respect to its longitudinal axis "L-L", that is to say with respect to the longitudinal axis of the grip element.

"T" represents a direction perpendicular to the axis of the traction element; "C" represents the circumferential direction of the tire, and may also be referred to as the longitudinal direction of the tire.

According to some embodiments (see e.g. fig. 3), the closed line constituting the shape of the recess according to the invention may be circular (such as e.g. the shape of the recess 4A) or elliptical or oval.

According to some embodiments (see for example fig. 4), the closing lines constituting the indentation pattern formed in the tyre according to the invention may be lobed (loboidal).

For example, the line associated with the notch 4B has a first and a second end lobe and an intermediate gradual portion, in particular connecting the two lobes; in particular, the two lobes of the notch 4B are identical.

In general, the number of lobes may be greater than one (e.g., two or three or four or … …) and/or the lobes may be the same or different from each other.

It should be noted that, due to the recesses, the inner tread portion or portions have a relative movement with respect to the tread during rolling of the tyre, locally increasing the specific pressure.

It will be appreciated that the (outer and inner) profiles of the peripheral recess (slightly separated and slightly spaced apart) are effective for both longitudinal (i.e. circumferential) and transverse adhesion. The greater the length of the recess profile, the better the grip.

The tread portion delimited by the recesses acts as a small block, so that the alternation of full and empty spaces has the slight effect of increasing the pressure on the ground at the edge of the tread portion.

As will be better explained below, noise and comfort are not affected if the distance between the (outer and inner) contours of the peripheral recess is not excessive.

Reducing the width of the recess reduces the mobility of the cover (cover) in rolling and further reduces the mobility if the recess does not open into an adjacent recess or rib. This effect is evident, in particular when the (outer and inner) profiles of the peripheral recess are arranged on the same horizontal plane.

For example, the distance between the outer and inner contours of the peripheral recess may preferably be between about 0.2mm and about 4.0mm, more preferably between about 0.5mm and about 1.5mm, and according to a particular embodiment about 0.8 mm.

As in the case of the example of fig. 3 and of fig. 4, the tread portion, in particular the portion 5A, may have a cylindrical shape (in particular hollow internally, as shown in the figures) or a truncated conical shape; in general, the cross-section of these bodies may be circular (as shown), elliptical or oval.

The tread portion 5A advantageously has a hole 6 (or alternatively a hollow), in particular a blind hole, in its interior.

In particular, the hole is advantageous during the production steps of the tyre (in particular for vulcanisation), since it can receive a hot tip, improving the diffusion of heat by evening the vulcanisation level of the composite component furthest from the heat source, and also when using the tyre, since it allows the dissipation of heat generated by the movement of the belts (beads) within the tyre and by the tread composite.

This advantage is even greater if the hole 6 (or hollow) is deeper than the bottom of the recess (as shown in fig. 3B).

In particular, the orifice 6 has a first (deep) terminal area 6A of conical shape (in particular with a rounded tip) and a second (shallow) terminal area 6B of truncated conical shape.

The inclination of the wall of the hole 6 is advantageous because if a small stone enters the hole during movement of the vehicle, it will be expelled during rotation of the tyre and will not remain in the hole.

It should be noted that the surface edges of the hole also contribute to the grip of the tire.

Preferably, the first end zone 6A and the second end zone 6B have different inclinations with respect to the axis of the orifice 6; in particular, the inclination of the first end region 6A is smaller than the inclination of the second end region 6B. Advantageously, the angle between the walls of the zone 6B is greater than the angle between the walls of the zone 6A, since the zone 6B is more critical for the stagnation of stones.

Preferably, between the first end zone 6A and the second end zone 6B, the orifice 6 has a step, i.e. a sharp change in its diameter, which decreases between the second end zone 6B and the first end zone 6A. Advantageously, the step acts as a further barrier preventing stones from being trapped in the hole 6.

As can be understood from the above explanation, one important aspect of the traction element is the relationship between the closed line related to the shape of the peripheral recess and the shape of the tread portion or inner tread portion; in fact, this relationship determines the width of the notch and indirectly affects noise and comfort.

Generally, the larger the notch size, the greater the noise generated, and varying the notch size and distance will vary the frequency of the noise generated.

In the example of fig. 3 and as seen in fig. 3A, the shape of the tread portion 5A corresponds to the shape of the closed line of the recess 4A.

In the example of fig. 4, there are a plurality of tread portions (with possibly separate grooves, as shown in fig. 4) adjacent to each other within the recess 4B.

Preferably, there are two or three or four tread portions. In particular, in the example of fig. 4, there are two tread portions 5A and one tread portion 5B. The tread portion 5A has a cylindrical shape (alternatively, it may also be a truncated cone) and has a circular cross section (alternatively, it may have an elliptical or oval cross section). The tread portion 5B has a substantially prismatic shape and connects the tread portions 5A; one of the functions of the tread portion 5B is to prevent the outer contour 46 of the recess 4B from deforming significantly and abruptly in the central region during rolling of the tire (i.e. to avoid excessive deformation of the tread).

Advantageously, the tread portion 5B thus acts as a "damper" and may contribute to the grip performance.

As can be seen in fig. 4, the plurality of tread portions 5A, 5B, 5A define a shape corresponding to the shape of the closed line of the recess 4B and also to the shape of the outer contour 46 of the recess 4B.

It should be noted that in the example of fig. 4, the edges that contribute to grip are: the edge of the outer contour 46 of the recess 4B, the entire circumferential edge of the tread portion 5A, the entire circumferential edge of the tread portion 5B, the surface edge of the aperture 6 of the tread portion 5A.

For example, in the case of the particular embodiment as constructed in FIG. 4, at about 250mm²In the region of (a), a total edge length of about 200mm is obtained.

Advantageously, if the inner tread portion is at the same level as the surrounding tread, the wear of the grip elements is equal to the wear of the surrounding tread, so that the grip, noise and comfort characteristics remain constant during the life of the tire; furthermore, the tire provides rolling resistance at the beginning of its life and maintains the same rolling resistance.

An important aspect of the grip element according to the invention is the dimensions of its components.

With particular reference to fig. 5B, an indication will be provided as to the possible sizing of the tread portion 5A and the related elements, as this tread portion is used in both the embodiment of fig. 3 and the embodiment of fig. 4.

It should be noted that these possible dimensioning settings are at least partly independent of each other.

Furthermore, it is to be noted that these possible dimensions are also used for tread portions having a similar configuration.

D1 denotes the surface diameter of the outer contour 41: preferably between about 30mm and about 5mm, even more preferably between about 20mm and about 7mm, and in particular embodiments it is equal to about 10 mm.

D2 denotes the surface diameter of the inner profile 42: preferably between about 30mm and about 4mm, even more preferably between about 20mm and about 5mm, and in particular embodiments it is equal to about 8.4 mm.

In particular, the difference between D1 and D2 defines the spacing between the tread portion 5A and the outer profile 41 described above.

D3 denotes the surface diameter of the orifice 6, in particular of the second end region 6B: preferably between about 20mm and about 2mm, even more preferably between about 10mm and about 3mm, and in particular embodiments it is equal to about 5 mm.

D4 denotes the first inner diameter of the bore 6: preferably between about 20mm and about 2mm, even more preferably between about 8mm and about 2mm, and in particular embodiments it is equal to about 3 mm.

D5 denotes the second inner diameter of the bore 6: preferably between about 20mm and about 2mm, even more preferably between about 8mm and about 2mm, and in particular embodiments it is equal to about 2.4 mm.

In particular, the first inner diameter D4 and the second inner diameter D5 are measured at the boundary between the first end region 6A and the second end region 6B, and their difference determines the extent of the aforementioned step.

Z1 denotes the depth of the second end region 6B of the hole 6, preferably equal to the depth of the notch 4A: preferably between about 10mm and about 3mm, even more preferably between about 8mm and about 3mm, and in particular embodiments it is equal to about 5 mm.

Z2 represents the depth of the first end region 6A of the orifice 6: preferably between about 20mm and about 6mm, even more preferably between about 16mm and about 6mm, and in particular embodiments it is equal to about 10 mm.

Alternatively, the value of Z2 may preferably be between about 400% and about 120% of the value of Z1, even more preferably between about 320% and about 120%, and in particular embodiments it is equal to about 200%.

A1 denotes the opening angle of the second end region 6B of the orifice 6: preferably between about 40 ° and about 10 °, even more preferably between about 25 ° and about 20 °, and in particular embodiments it is equal to about 23 °.

A2 denotes the opening angle of the first end region 6A of the orifice 6: preferably between about 20 ° and about 3 °, even more preferably between about 15 ° and about 5 °, and in particular embodiments it is equal to about 9 °.

With particular reference to fig. 5A, an indication will be provided as to possible further dimensioning of the ground engaging elements.

XL denotes the distance between the design axes of the two tread portions of a single traction element, in particular the distance measured along the direction indicated by the axis L-L in fig. 4. Preferably, XL is between about 60mm and about 10mm, even more preferably between about 45mm and about 15mm, and in particular embodiments it is equal to about 20 mm.

YT represents the width of the pinch point of the transition between two lobes, measured in particular perpendicularly to the direction represented by the axis L-L of figure 4, in the above-described configuration. Preferably, YT is between about 15mm and about 3mm, even more preferably between about 9mm and about 4mm, and in particular embodiments it is equal to about 5.8 mm.

Alternatively, the value of YT may preferably be between about 30% and about 90%, even more preferably between about 50% and about 70%, and in particular embodiments it is equal to about 58% of the value of the width or diameter of the lobe.

With the aid of fig. 2, a possible use of the grip element according to the invention in a tyre will be explained.

The figure shows several grip elements, which are aligned, in particular, on different circumferences of the tire. Alternatively, the plurality of traction elements may be located, for example, within the circumferential band of the tire, and optionally arranged to the right and left of the central circumference, preferably at a distance of between about 0mm and about 60mm from the circumference itself. The plurality of traction elements may be spaced apart from each other on the circumference of the tire, preferably by a distance of between about 10mm and about 120 mm.

For example, a first plurality of traction elements 32 are formed on the first rib 22. The elements 32 are in particular identical to each other. The element 32 has in particular a shape with two lobes. Element 32 has, in particular, the same first direction with respect to the circumferential direction of the tyre (indicated with "C" in figure 4), preferably the direction of an "alpha" angle (see figure 4) oriented between about 0 and about 90 degrees, more preferably between about 30 and about 60 degrees, and according to a particular embodiment, about 52 °.

In particular, a larger "alpha" angle favors the lateral grip of the tire, while a smaller "alpha" angle favors the longitudinal grip of the tire.

For example, a second plurality of traction elements 31 or 33 are formed on the second ribs 21 or 23. In the example of fig. 2, there are grip elements on both the ribs 21 and 23; in particular on the ribs 23, there are two sets of a plurality of grip elements.

The grip elements 31 are in particular identical to each other. The grip elements 33 are in particular identical to each other. The element 33 has in particular a circular shape. The element 31 has in particular a shape with two lobes. The elements 31 have in particular the same second direction with respect to the circumferential direction of the tyre (indicated with "C" in figure 4), preferably the direction of an "alpha" angle (see figure 4) ranging from about 0 ° to about-90 °, more preferably from about-30 ° to about-60 °, according to a particular embodiment, about-52 °.

As can be seen from fig. 2, the first direction is different from the second direction; in particular, these two directions are equal and opposite with respect to the circumferential direction of the tyre (indicated by "C" in figure 4).

Referring to fig. 2, the width of the five ribs 21, 22 and 23 is preferably between about 20mm and about 70mm, even more preferably between about 35mm and about 55mm, which in a particular embodiment is equal to about 45 mm.

Furthermore, the mutual distance between the aforementioned five ribs 21, 22 and 23 (i.e. the width of the four offset circumferential grooves) is preferably between about 2.5mm and about 30mm, even more preferably between about 15mm and about 25mm, and in a particular embodiment it is equal to about 20 mm.

These dimensions and the number of ribs are not restrictive but indicative.

In the example of fig. 2 again, the circular grip member has a diameter of about 10mm, while the lobed grip member has a length of about 30mm and a width of about 10mm, and is inclined by about 50 ° with respect to the circumferential direction; the widths of these dimensions and angles are not restrictive, but are merely indicative.

In the diagrams of fig. 6 to 13, some possible configurations of the tread of a tire according to the invention are shown, which employ convex grip elements (for example similar to that of fig. 3) and/or convex grip elements, in particular with convex corners (for example similar to that of fig. 4).