Improved tires

Abstract

The present invention relates to a tire (1), comprising: a carcass (5); at least one high elongation belt (1, 2, 3, 4) applied to the outside of the carcass (5) in a single cord manner; and an outer tread portion (6), which is provided with two or more grooves (7) extending around the tread portion (6) according to a circumferential direction (L), wherein at least one of the grooves (7) has an axial width (Wg) of at most 2 mm measured according to an axial direction (A) parallel to the rotation axis (R) of the tire (10) and orthogonal to the circumferential direction (L).

Description

Technical Field

[0001] The present invention relates to an improved tire having a closed lug design on the tread, and more particularly to a truck or bus tire. Background Art

[0002] Tires provided with "closed tread technology" are well known in the art.

[0003] Conventional truck or bus tire treads are characterized by having a geometry of one or more longitudinal grooves with a width ranging from 6 mm to 15 mm. "Closed pattern technology" provides a technique to reduce the width of one or more tread grooves, resulting in a groove width typically ranging from 0.5 mm to 4 mm, with the goal of improving tire rolling losses.

[0004] Tire rolling losses are due to the cyclic deformation of the tire under rolling conditions and depend on rubber strain, material viscoelasticity and rubber volume according to the following known relationship (where RRc is the rolling resistance coefficient):

[0005] RRc=tanδ·volume·strain

[0006] According to standard practice, the closed pattern design of the tread allows for reduced rolling resistance by increasing the tread compression stiffness and reducing rib / block deformation under loading / rolling. As an example, in Figure 2 A graph is shown in which each portion of the graph below the groove image numbered by I, II or III (corresponding to small grooves, medium grooves and large grooves, respectively) refers to the void fraction of a specific type of groove. In this specification, if the width of the groove is equal to about 2 mm, it is defined as "small", if the width of the groove is equal to about 6 mm, it is defined as "medium", and if the width of the groove is equal to about 10 mm, it is defined as "large". In the graph, the growth of rolling resistance from small grooves to large grooves (groove images I to III) is shown by line A, where the dotted line B indicates that the stiffness decreases from small grooves to large grooves.

[0007] In order to evaluate how this technical effect is achieved, it should be taken into account that the ribs are subjected to vertical pressure during the rolling of the tire. Due to the Poisson effect of the rubber, the deformed shape of the ribs will expand in a direction perpendicular to the direction of compression, thus contributing to the overall rolling resistance of the tire.

[0008] In a closed pattern, the groove walls are reduced in distance (which causes the opposite sides of the groove to interlock and deform during tire rolling). FIG. 3A to FIG. 3C )) to increase the tire compression stiffness.

[0009] One of the trade-offs of a closed tread design is an increase in the ply steering effect, which has a negative impact on tire wear and irregular wear. Specifically, the rolling resistance coefficient RRc associated with a closed tread tire is approximately 2% lower than that of a standard tread tire.

[0010] Typically, tire crown structures are made of multiple plies bonded together to achieve a multi-ply system that twists and bends when subjected to simple tensile loads. The result is a combination of bending, shearing, and stretching of the laminate.

[0011] Furthermore, when the tire is in free rolling conditions, the toroidal shape of the tire flattens at the contact point, thus generating lateral and longitudinal shear stresses in the contact area (tread blocks). In addition, in the plane, shear also occurs due to the change in belt tension at the contact point. Such shear stress applied to the individual tread blocks causes a reaction force of the coupling, resulting in a self-aligning torque.

[0012] Thus, the tire generates measurable lateral forces and self-righting moments under straight rolling conditions. Ply lateral force, which is a non-zero lateral force at zero slip angle, is an inherent property of belted radial tires.

[0013] During the inflation phase, a tensile force is generated that stretches the belt package (causing the ply to turn), so tire loading / bending causes belt tension to relax. The more the tire bends, the more belt slack there is, and therefore the ply turning force is less. The closed pattern strengthens the tire crown and limits tire bending, resulting in less belt slack and greater ply turning force.

[0014] In order to evaluate the influence of tread geometry on the carcass turning effect, FEM simulations have been performed using two different tread geometries (standard and closed). The results of this simulation are presented in the attached Figure 4 and attached Figure 5 , and clearly shows that the closed pattern geometry results in a negative increment in the ply steering effect. Summary of the invention

[0015] The technical problem proposed and solved by the present invention is therefore that of providing a tyre which allows overcoming the drawbacks mentioned above with reference to the prior art.

[0016] This problem is solved by a tyre according to claim 1. Preferred features of the invention are the object of the dependent claims.

[0017] According to a first aspect of the invention, there is provided a tire comprising a carcass, a tread portion provided with a closed lug design and at least one high elongation (HE) belt applied in a single-cord manner or in a multi-cord strip manner, in particular arranged between bias working belts.

[0018] In the present application, the term "high elongation belt" refers to a belt characterized by a stiffness modulus that varies as a function of strain. In particular, the stiffness modulus is proportional to the strain, which means that the stiffness modulus is lower for small strains and higher for larger strains.

[0019] This allows the cord (or cords) to expand during the vulcanization process and ensures a high modulus of stiffness during operation.Steel cords (or cords) guarantee this technical effect due to the geometry of the strands.

[0020] For greater clarity, a high elongation belt is a belt embedded with cords provided with a modulus of stiffness varying between about 3,000 MPa (low modulus, from 0 to about 2% strain or elongation) to 125,000 MPa (high modulus, for strains greater than about 2%), said cords having an elongation at break of between 2.5% and 3.5%, measured on samples extracted from a cured tire.

[0021] There are currently available a number of known types of high elongation belts.

[0022] According to the invention, at least one high elongation belt may be applied in the form of a single cord or in the form of a strip of multiple cords, for example six or nine cords.

[0023] To this end, the above stiffness properties are not due to the belt itself, but rather to the single cord construction (ie, a plurality of single cords arranged parallel to one another or strips of six or nine cords also arranged parallel to one another) constituting the belt.

[0024] The application of at least one high elongation belt, preferably a system comprising one or at most two high elongation belts, offers great advantages over conventional belt constructions.

[0025] The latter traditional type of construction (cf. small truck tires or bus tires) generally provides for the placement of one or two longitudinal "corrugated belts" (also called "wavy belts"), applied as strips of several calendered cords (preferably nine cords) with a certain "placement angle" or "belt cord angle" θ. Moreover, the edges of such strips need to be protected with additional overlaps of belt strips to avoid durability problems.

[0026] Furthermore, during the construction of a conventional (corrugated) tire, after winding nine cord strips, in order to avoid the persistence of free cords, an extra full turn of strip is added at the beginning and end of the winding: in this way, a return edge is achieved.

[0027] The presence of belt strip application angle and return edges affects the ply cornering forces (increases them) because of the increased thickness between the crossing belts (turned edges) and also provides a residual belt cord angle θ.

[0028] In contrast, at least one high elongation belt of the claimed invention is applied in a single cord strip.Switching from a multi-cord strip to a single cord greatly reduces the belt cord angle θ and also avoids the need for a turned-back edge (no free edge).

[0029] In particular, at least one high elongation belt is applied at 0° (as a longitudinal belt). Advantageously, due to the small belt cord angle θ applied by HE, the lower asymmetry of the belt package will result in lower ply steering forces.

[0030] The comparative table 1 provided below shows the differences between the belt system of the prior art and the preferred embodiment of the belt system according to the claimed invention provided with one high elongation belt with respect to factors such as the axial width A and the belt cord angle θ (included in Figure 1 and Figure 2 The main difference in the parameters of the angle between the cords and the longitudinal direction L) shown in , the two compared belt systems have the same closed pattern and include four belts (numbered 1 to 4):

[0031] Table 1

[0032]

[0033] The letters L and R reported near the belt cord angle values ​​in Table 1 correspond to the left or right direction, respectively, from which the magnitude of the associated belt cord angle is measured starting from the circumference. R corresponds to the angle measured clockwise from the circumference, while L corresponds to the angle measured counterclockwise from the circumference.

[0034] In the attached Figure 6 In the present invention, experimental data (wear energy in several tire tread points) are reported, showing how the carcass cornering forces vary from the above-mentioned prior art belt system (in particular corrugated tire) and a preferred embodiment of the belt system according to the claimed invention (high elongation tire) (cf. Table 1).

[0035] exist Figure 6 In FIG. 1 , the portion of the abscissa axis ranging from about −125 mm to 125 mm refers to the lateral position of the point under consideration on the tread. Figure 6It is clearly shown that for a fixed lateral force (Fy=0), the average slip angle of the prior art corrugated tire is higher, which means that the prior art tire is associated with a higher ply cornering force when the slip angle is equal to 0°.

[0036] Thus, the combination of closed pattern technology with at least one high elongation belt according to the claimed tire construction allows to obtain lower ply cornering forces and, therefore, lower wear and irregular wear properties of the tire.

[0037] That is, applying at least one high elongation belt to a closed lug tire allows to counteract the negative effects provided by the closed lug and enjoy only its positive effects.

[0038] Other advantages, features and modes of using the invention will become apparent from the following detailed description of some embodiments presented by way of example and not by way of limitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Reference will be made to the accompanying drawings, in which:

[0040] Figure 1 shows a schematic cross-sectional view of a preferred embodiment of a tyre according to the invention, only one section of which some parts are illustrated for the sake of greater clarity;

[0041] Figure 1A is included in Figure 1 A simplified representation of a top view of the four belts in the tire shown;

[0042] Figure 2 is a graph showing rolling resistance trends as a function of volume void fraction %;

[0043] Figure 3A A schematic cross-sectional view of a prior art tire provided with a closed lug tread is shown;

[0044] Figure 3B Shows Figure 3A details, especially those related to the latter under loading conditions. Figure 3A Standard grooves in the tire tread pattern;

[0045] Figure 3C Shows Figure 3A Detail of the enlargement, especially with respect to the rear part subjected to vertical loads Figure 3A The tire tread pattern has closed tread grooves;

[0046] Figure 4 are diagrams showing the trend of residual force Fy as a function of slip angle for standard pattern and closed pattern tread designs, respectively;

[0047] Figure 5shows example values ​​of the ply steering effect with reference to a standard tread tire according to the prior art and a closed tread tire according to the prior art;

[0048] Figure 6 Exemplary values ​​of wear energy are shown with reference to a standard corrugated tire according to the prior art and a tire provided with a high elongation belt and a closed lug tread according to a preferred embodiment of the invention.

[0049] The dimensions and thicknesses and curvatures shown in the above-introduced drawings should be understood to be purely exemplary and not necessarily shown to scale. In addition, as mentioned above, in the drawings, some layers / components of the tire may have been omitted in order to more clearly illustrate various aspects of the invention. DETAILED DESCRIPTION

[0050] Hereinafter, several embodiments and modifications of the present invention will be described with reference to the drawings introduced above.

[0051] Furthermore, when the different embodiments and modifications described below are compatible, they may be used in combination.

[0052] The improved tire according to the present invention provides a new belt construction combined with a closed lug design of the tread to balance the ply steering tradeoff and enhance rolling resistance RRc and wear performance, thereby avoiding the disadvantages of prior art tires having a closed lug design.

[0053] As described above, the tire according to the present invention comprises a tread portion provided with two or more grooves designed to realize a closed pattern. Figure 1 A preferred embodiment of the tyre 10 comprises a tread portion 6 provided with two or more grooves 7 extending according to a circumferential direction L around said tread portion 6 .

[0054] An axial width Wg of at least one of the grooves 7 measured according to an axial direction A parallel to the axis of rotation R of the tyre 10 and orthogonal to the circumferential direction L ranges from 0.5 to 4 mm, in particular less than or equal to 2 mm.

[0055] The axial width Wg of the groove 7 is substantially constant over the entire depth of the groove. By "substantially" it is meant that the groove walls, at the points where they intersect the tread rolling surface, may have a slight inclination of between 2 and 5 degrees relative to a normal plane.

[0056] A radial depth Dg of at least one of the grooves 7 measured according to the radial direction of the tire 10 is in the range of 7 to 14 mm, preferably in the range of 8 to 13 mm, more preferably in the range of 9 to 12 mm.

[0057] In a preferred embodiment, at least one of the grooves 7 is the groove closest to the tire equatorial plane CL (or center line CL) in the tire axial direction.

[0058] The tire equatorial plane CL is a plane that divides the tread portion 6 into two equal-width portions.

[0059] In another preferred embodiment, two of the grooves 7 are grooves closest to the tire equatorial plane CL (or center line CL) in the tire axial direction.

[0060] In another preferred embodiment, two of the grooves 7 are the grooves closest to the tire equatorial plane CL (or center line CL) in the axial direction of the tire, wherein the two grooves 7 are arranged on both sides of the tire equatorial plane CL (or center line CL) in the axial direction of the tire (one on each side).

[0061] In another preferred embodiment, one, two or three of the grooves 7 are arranged on both sides of the tire equatorial plane CL (or center line CL) in the tire axial direction.

[0062] The advantage of the grooves 7 being located in the central region of the pattern (ie in the region close to the equatorial plane CL) is that the rigidity of the tread pattern is thereby increased, resulting in improved rolling resistance.

[0063] In a preferred embodiment, said grooves 7 are positioned within a maximum axial distance from the equatorial plane CL corresponding to 30% of the axial width W1 , W2, W3, W4 of the widest tread belt 1 , 2, 3, 4.

[0064] The tire 10 according to the invention also comprises a carcass 5 (which may comprise one or more inner carcass plies) and at least one high elongation belt. The at least one high elongation belt is radially applied to the outside of the carcass 5 in the form of a single cord.

[0065] According to a particular embodiment of the invention, at least one high elongation belt is applied to the radially outermost side of the inner carcass ply of the tire. According to a preferred embodiment of the invention, there is provided a tire comprising a plurality of belts radially superposed on each other, the tire comprising a high elongation belt corresponding to a second belt starting from the carcass towards the tread portion.

[0066] according to Figure 1 In the preferred embodiment shown, the tire 10 comprises four belts, in particular a first belt, a second belt, a third belt and a fourth belt (indicated by reference numerals 1, 2, 3, 4 respectively) starting from the carcass 5 towards the tread portion 8.

[0067] Preferably, each of the four belts 1, 2, 3, 4 is provided with a corresponding belt cord angle (in Figure 1Aθ1, θ2, θ3 and θ4, respectively), and more preferably, each of the belt cord angles θ1, θ2, θ3, θ4 is different from the other belt cord angles.

[0068] At least one of the first belt 1, the second belt 2, the third belt 3 and the fourth belt 4 is a high elongation belt applied in a single-cord manner and having a belt cord angle equal to 0. That is, the high elongation belt is configured as a longitudinal belt.

[0069] In particular, the single cords are applied in a spiral manner and, thanks to this application, it is advantageous to obtain a belt cord angle equal to 0°.

[0070] Preferably, the value of each belt cord angle θ1 , θ2, θ3, θ4 measured relative to the circumferential axis L is in the range of 0° to 80°.

[0071] More specifically, the belt cord angle is the smallest angle (having a positive or negative magnitude value, where a positive magnitude is measured in a clockwise direction and a negative magnitude is measured in a counterclockwise direction) comprised between the circumferential axis L and the main extension axis of the cord. Figure 1A , belt cord angles θ1 and θ4 are shown having a magnitude equal to about 45° according to the counterclockwise direction.

[0072] according to Figure 1 and Figure 1A In the preferred embodiment of the invention shown in , the second belt 2 is provided as a high elongation belt, applied in single-cord fashion and configured to define a second belt cord angle θ2 equal to 0° (as already described).

[0073] In particular, the tire 10 includes: a first belt 1, which defines a first belt cord angle θ1 in the range of 35° to 60°; a second high elongation belt 2, which defines a second belt cord angle θ2 equal to 0°; a third belt 3, which defines a third belt cord angle θ3 in the range of 20° to 40°; and a fourth belt 4, which defines a fourth belt cord angle θ4 in the range of 40° to 60°.

[0074] According to a preferred embodiment of the present invention, the angle of each belt relative to the first belt cord angle θ l The ratio between them is defined as follows:

[0075] - the second belt cord angle θ2 is equal to 0°;

[0076] a third belt cord angle θ3 equal to 60% to 80% of the first belt cord angle θ1, preferably equal to 70% of the first belt cord angle θ1, and

[0077] The fourth belt cord angle θ4 is equal to 120% to 140% of the first belt cord angle θ1 , preferably equal to 130% of the first belt cord angle θ1 .

[0078] According to a more preferred embodiment of the present invention, the first belt 1 defines a first belt cord angle θ1 equal to 40°, the second belt 2 defines a second belt cord angle θ2 equal to 0°, the third belt 3 defines a third belt cord angle θ3 equal to 28°, and the fourth belt 4 defines a belt cord angle θ4 equal to 52°.

[0079] In contrast, according to an alternative embodiment of the invention, only the first belt 1 is a high elongation belt, applied in single-cord fashion and defining, according to this embodiment, a first belt cord angle θ1 equal to 0°.

[0080] According to yet another embodiment of the invention, the first belt 1 and the second belt 2 are both high elongation belts applied in single-cord fashion and defining first and second belt cord angles θ1 and θ2 respectively equal to 0°.

[0081] Reference again Figure 1 and Figure 1A In the preferred embodiment of the tire 10 shown in FIG. 1 , each of the first belt 1, the second belt 2, the third belt 3 and the fourth belt 4 has a respective width W1, W2, W3, W4 ranging from 100 mm to 300 mm measured according to the axial direction A. According to a preferred embodiment of the present invention, the width may be in the range of 130 mm to 250 mm.

[0082] According to a preferred embodiment of the present invention, the ratio between the widths W2, W3, W4 of the second belt 2, the third belt 3 and the fourth belt 4 relative to the width W1 of the first belt 1 is defined as follows:

[0083] the width W2 of the second belt 2 is equal to 85% to 100%, preferably equal to 92% to 94% of the width W1 of the first belt 1,

[0084] the third belt has a width W3 equal to 95% to 115%, preferably equal to 107% to 109% of the width W1 of the first belt 1 , and

[0085] The fourth belt 4 has a width W4 equal to 45% to 60% of the width W1 of the first belt 1 , preferably equal to 55% to 57% of the width W1 of the first belt 1 .

[0086] In particular, the first belt 1 has a first width W1 equal to 230 mm, the second belt 2 has a second width W2 equal to 215 mm, the third belt 3 has a third width W3 equal to 250 mm and the fourth belt 4 has a fourth width W4 equal to 130 mm.

[0087] like Figure 1 As can be seen in the figure, four belts 1, 2, 3, 4 are radially superposed on each other in such a way as to realize a sandwich structure or belt system. In particular, the first belt 1 is at the innermost position and the fourth belt 4 is at the outermost position relative to the other belts 2, 3. According to such an embodiment, the second belt 2 is interposed between the first belt 1 and the third belt 3, and the third belt 3 is interposed between the second belt 2 and the fourth belt 4.

[0088] The tire according to the above disclosed embodiments is particularly suitable for use as a truck or bus tire.

[0089] The invention has been described herein with reference to preferred embodiments. Other embodiments are possible within the same inventive core, as defined by the protective scope of the appended claims.

Claims

1. A tire (10), comprising: - Carcass (5); - at least one high elongation belt (2) applied in the form of a single cord to the radially external part of the carcass (5), The high elongation belt (2) is embedded with cords, and the cords are provided with a stiffness modulus varying between 3,000 MPa and 125,000 MPa, wherein the stiffness modulus of 3,000 MPa is for strain values ​​of the cords ranging from 0 to 2%, and the stiffness modulus of 125,000 MPa is for strain values ​​of the cords greater than 2%; as well as - an outer tread portion (6) provided with two or more grooves (7) extending around said tread portion (6) according to a circumferential direction (L), wherein an axial width (Wg) of the two grooves (7) measured along an axial direction (A) parallel to the rotation axis (R) of the tire (10) and orthogonal to the circumferential direction (L) is less than or equal to 2 mm, The tire (10) comprises a first belt (1), a second belt (2), a third belt (3) and a fourth belt (4), wherein the first belt (1), the second belt (2), the third belt (3) and the fourth belt (4) each have a corresponding belt cord angle (θ1, θ2, θ3, θ4), wherein at least one of the first belt (1), the second belt (2), the third belt (3) and the fourth belt (4) is a high elongation belt (2) applied in a single-cord manner and having a belt cord angle (θ2) equal to 0°, The ratio of the belt angle to the first belt cord angle (θ1) is defined as follows: - the second belt cord angle (θ2) is equal to 0°; - said third belt cord angle (θ3) is equal to 60% to 80% of said first belt cord angle (θ1), and - The fourth belt cord angle (θ4) is equal to 120% to 140% of the first belt cord angle (θ1).

2. The tire (10) according to claim 1, characterized in that The third belt cord angle (θ3) is equal to 70% of the first belt cord angle (θ1).

3. The tire (10) according to claim 1, characterized in that The fourth belt cord angle (θ4) is equal to 130% of the first belt cord angle (θ1).

4. The tire (10) according to claim 1, characterized in that The cords embedded in the high elongation belt (2) have an elongation at break between 2.5% and 3.5%.

5. The tire (10) according to any one of claims 1 to 4, characterized in that The two grooves (7) have a depth in the radial direction, and the axial width (Wg) of the two grooves (7) is substantially constant over the entire depth of the grooves (7).

6. The tire (10) according to claim 1, characterized in that The first belt (1), the second belt (2), the third belt (3) and the fourth belt (4) are radially superimposed on each other starting from the first belt (1) to the fourth belt (4), wherein the first belt (1) is at an innermost position and the fourth belt (4) is at an outermost position relative to the other belts (2, 3).

7. The tire (10) according to claim 1 or 6, characterized in that The second belt (2) is a high elongation belt applied in single-cord fashion and having a belt cord angle (θ2) equal to 0°.

8. The tire (10) according to claim 1 or 6, comprising: - a first belt (1) defining a first belt cord angle (θ1) in the range of 35° to 60°; - a second high elongation belt (2) defining a second belt cord angle (θ2) equal to 0°; - a third belt (3) defining a third belt cord angle (θ3) ranging from 20° to 40°; and - a fourth belt (4) defining a fourth belt cord angle (θ4) ranging from 40° to 60°.

9. The tire (10) according to claim 8, characterized in that: - the first belt cord angle (θ1) is equal to 40°; - said third belt cord angle (θ3) is equal to 28°; and - The fourth belt cord angle (θ4) is equal to 52°.

10. The tire (10) according to claim 1, characterized in that Each of the first belt (1), the second belt (2), the third belt (3) and the fourth belt (4) has a respective width (W1, W2, W3, W4) ranging from 100 mm to 300 mm measured according to the axial direction (A).

11. The tire (10) according to claim 10, characterized in that The widths (W1, W2, W3, W4) are in the range of 130 mm to 250 mm.

12. The tire (10) according to claim 10 or 11, characterized in that The ratios of the width (W2) of the second belt (2), the width (W3) of the third belt (3) and the width (W4) of the fourth belt (4) relative to the width (W1) of the first belt (1) are defined as follows: - the width (W2) of the second belt (2) is equal to 85% to 100% of the width (W1) of the first belt (1), - the width (W3) of the third belt is equal to 95% to 115% of the width (W1) of the first belt (1), and - The width (W4) of the fourth belt (4) is equal to 45% to 60% of the width (W1) of the first belt (1).

13. The tire (10) according to claim 12, characterized in that The width (W2) of the second belt (2) is equal to 92% to 94% of the width (W1) of the first belt (1).

14. The tire (10) according to claim 12, characterized in that The width (W3) of the third belt is equal to 107% to 109% of the width (W1) of the first belt (1).

15. The tire (10) according to claim 12, characterized in that The width (W4) of the fourth belt (4) is equal to 55% to 57% of the width (W1) of the first belt (1).

16. The tire (10) according to claim 11, comprising: - a first belt (1) having a first width (W1) equal to 230 mm; - a second belt (2) having a second width (W2) equal to 215 mm, - a third belt (3) having a third width (W3) equal to 250 mm; and - a fourth belt (4) having a fourth width (W4) equal to 130 mm.

17. The tire (10) according to claim 6, characterized in that The first belt (1) is applied in the form of a single cord and has a belt cord angle (θ) equal to 0° l ) of high elongation belts.

18. The tire (10) according to claim 17, characterized in that The first belt (1) and the second belt (2) are both high elongation belts applied in single-cord fashion and defining belt cord angles (θ1, θ2) equal to 0°.

19. The tire (10) according to any one of claims 1 to 4, characterized in that Two of the two or more grooves (7) are grooves closest to the tire equatorial plane (CL) in the tire axial direction.

20. The tire (10) according to claim 19, characterized in that The two grooves (7) are arranged one on each side of the tire equatorial plane (CL) in the tire axial direction.

21. The tire (10) according to claim 20, characterized in that More than one groove (7) is arranged on each side of the equatorial plane (CL) in the tire axial direction.

22. The tire (10) according to claim 20, characterized in that Between one and three grooves (7) are arranged on each side of the equatorial plane (CL) in the tire axial direction.

23. The tire (10) according to any one of claims 1 to 4, characterized in that The tire is a truck tire.

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