Tire and a lamella plate for the manufacture of a sipe of a tire

[0001] This U.S. patent application claims the benefit of European Patent Application No. EP22151616.4 filed with the European Patent Office on Jan. 14, 2022, the entire contents of which is incorporated herein by reference.

[0002] The present invention relates to a tire having tread blocks, and being provided in the tread blocks with sipes, more particularly to an improved shape of a sipe being capable of providing better traction of the tire. The present invention also relates to a lamella plate that is used in the manufacturing process of a tire for making said sipe. The present invention also relates to the use of said lamella plate for manufacturing a tire.

[0003] A tread of a known pneumatic tyre is indicated in FIG. 1a. A pneumatic tire is known to include a tread which has circumferential and transversal grooves on its outer surface, said grooves defining a number of tread blocks. The tread is meant for a rolling contact against a ground surface, such as road. The grooves are meant for draining water and/or slush that is possibly located on the ground surface away from the tread, so that the contact between the tread and the ground surface is as good and consistent as possible. Referring to FIG. 2b, some tires are provided in the tread with a number of sipes (S₁₁, S₂₁, S₁₂, S₂₂) at various angles with respect to a motion direction of the tire. The sipes not only serve a better tire-ground contact in the rain, but also improve traction, braking and lateral stability on snow by trapping snow as well as providing more gripping edges. The sipes also make the rubber material to deform more easily, in effect making the tire appear softer. This also improves friction. A purpose of the invention is to improve grip, stability, and handling of the tire.

[0004] Lamella plates are commonly used in the manufacturing process of a pneumatic tire for making said sipes. The lamella plate is included in a mould, in which the tire is made. After vulcanizing the tire, the tire is removed from the mould, and the lamella plates are removed from the tread. The locations where the lamella plates were arranged define the sipes of the tread. A purpose of the invention is to present a lamella plate that can be used to manufacture the tire with improved grip.

[0005] For improved traction, the opposing walls of a sipes should lock to each other properly particularly during breaking and acceleration and in presence of lateral forces. While some degree of locking is known to occur in some special sipes, the locking of the sipes is not always optimal. An object of the invention is to improve the properties of a tire provided with sipes in the tread blocks so that the sipes can work more efficiently in the sense of improved gripping, improved stability, and improved handling, because of the more efficient locking of the sipe walls.

[0006] It is also an object of the invention to provide a lamella plate that is able to make the sipe according to the present invention.

[0042] The embodiments relate to a tire having tread blocks and a lamella plate for manufacturing a tire. The tire is preferably a pneumatic tire. At least some tread blocks are provided with sipes. To improve locking of sipe walls, opposite walls of a sipe, preferably opposite walls of many sipes, are provided with an indentation and a protrusion. Herein the term sipe refers to a narrow groove provided in a tread block of a tire. In between two parallel sipes, a lamella may be arranged. The term lamella refers to a narrow piece of tread block material in between two sipes. As an example, FIG. 1b shows a lamella LAM in between the sipes S₁₁ and S₂₁. A lamella plate is a plate that is usable for forming a sipe in a moulding process. When a lamella plate is embedded to uncured rubber, and removed therefrom after curing the rubber, the sipe is formed.

[0043] In the present case, novel features of the tire 100 are derivable from the shape of the lamella plate 500 used for forming the sipe(s). Therefore, embodiments of a lamella plate 500 are defined first. As well known, because of the moulding process, a shape of the sipe formed by the lamella plate is geometrically congruent with the part of the lamella plate that is arranged in the tread of the tire during moulding.

[0044] FIG. 2a shows, in a side view, a lamella plate 500 for forming a sipe to a tire. Somewhat similar lamella plate 500 is shown in FIG. 8a in a perspective view; in FIG. 8b in a side view; and in FIG. 8c in a top view. FIG. 2c shows the cross section A-A of FIG. 2a. Thus, referring to FIGS. 2a, 2c, and 8a to 8c, the lamella plate 500 comprises a first surface 510 and a second surface that is opposite 520 to the first surface 510. The first surface 510 is provided with a first primary plate indentation PI₁₁ and a first primary plate protrusion PP₁₁. The first primary plate indentation PI₁₁ may have been made to a plate by pressing the indentation PI₁₁ thereto. Alternatively, the plate 500 may have been made by additive manufacturing. When manufacturing the tire 100, a part of the lamella plate 500 is arranged in a tread 110 of the tire such that the direction SR of FIG. 2a is parallel to a radial direction SR of the tire (see FIG. 1a) at the point of the lamella plate 500. The directions SS and ST in FIG. 2a are orthogonal to SR, and ST is a direction of a thickness of the lamella plate. This concerns also FIG. 2c.

[0045] As detailed above, a purpose of the invention is to lock walls of a sipe to each other during braking, acceleration, and/or driving on a curve. Braking and acceleration cause circumferential forces to the tire, and driving on a curve causes lateral forces to the tire. In this way, the locking of the walls of the sipes improves grip, stability, and handling of the tire. Therefore, and referring to FIG. 2c, the second surface 520 is provided with a second primary plate protrusion PP₂₁ that is opposite to the first primary plate indentation PI₁₁. The second surface 520 is also provided with a second primary plate indentation PI₂₁ that is opposite to the first primary plate protrusion PP₁₁.

[0046] In the lamella plate 500, the first surface 510 defines a first primary lamella plate surface LPS₁₁. In the embodiments shown e.g. in FIGS. 2a to 2d and 8a to 8c, the first primary lamella plate surface LPS₁₁ has the shape of a planar surface. However, in the embodiment shown in FIGS. 11a to 11c, the first primary lamella plate surface LPS₁₁ has the shape of a curved surface. The first surface 510 defines the first primary lamella plate surface LPS₁₁ such that the first surface 510 comprises the first primary lamella plate surface LPS₁₁.

[0047] The first primary plate protrusion PP₁₁ protrudes from the first primary lamella plate surface LPS₁₁ and the first primary plate indentation PI₁₁ descends into the first primary lamella plate surface LPS₁₁. Preferably, an area of the first primary lamella plate surface LPS₁₁ is at least 10%, more preferably at least 50%, of an area of the first primary plate protrusion PP₁₁. Preferably, an area of the first primary lamella plate surface LPS₁₁ is at least 10%, more preferably at least 50%, of an area of the first primary plate indentation PI₁₁.

[0048] In the lamella plate 500, the second surface 520 defines a second primary lamella plate surface LPS₂₁. In the embodiments shown e.g. in FIGS. 2a to 2d and 8a to 8c, the second primary lamella plate surface LPS₂₁ has the shape of a planar surface. However, in the embodiment shown in FIGS. 11a to 11c, the second primary lamella plate surface LPS₂₁ has the shape of a curved surface.

[0049] The second surface 520 defines the second primary lamella plate surface LPS₂₁ such that the second surface 520 comprises the second primary lamella plate surface LPS₂₁.

[0050] The second primary plate protrusion PP₂₁ protrudes from the second primary lamella plate surface LPS₂₁ and the second primary plate indentation PI₂₁ descends into the second primary lamella plate surface LPS₂₁.

[0051] Concerning the both the first primary lamella plate surface LPS₁₁ and second primary lamella plate surface LPS₂₁, both these surfaces may be planar surfaces. In the alternative, both these surfaces may be curved surfaces. Herein a curved surface refers to a planar surface that is obtainable by bending a plane about (i) an axis, (ii) axes that are parallel with each other and lying on only one side of the planar surface, or (iii) (iii,a) at least one primary axis, which is/are parallel with a primary direction and lying on a same side of the plane and (iii,b) at least one secondary axis, which is/are parallel with a secondary direction that is different from the primary direction, the secondary axes/axis lying mutually on a same side of the plane. The secondary axes may be arranged on a different side than the primary axes. Preferably, the first primary lamella plate surface LPS₁₁ and second primary lamella plate surface LPS₂₁ are planar or curved such that they are obtainable from a planar surface by bending about only one axis or by bending about only such axes that are parallel with each other and that are on a same side of the planar surface. Even more preferably, the first primary lamella plate surface LPS₁₁ and second primary lamella plate surface LPS₂₁ are planar or curved such that they are obtainable from a planar surface by bending about one axis or by bending about only such axes that are parallel with each other such that a radius of curvature about the axis/axes is constant throughout the lamella plate surfaces LPS₁₁, LPS₂₁.

[0052] It is noted that the lamella plate may be, but need not be, manufactured from a planar plate. As an alternative, a lamella plate may be manufactured using an additive manufacturing technique (including e.g. rapid prototyping and various sintering techniques). Thus, the shape of the first primary lamella plate surface LPS₁₁ and second primary lamella plate surface LPS₂₁ as disclosed above does not restrict the manufacturing method to a method comprising bending a plate.

[0053] In FIGS. 11a to 11c, the lamella plate surfaces LPS₁₁, LPS₁₂, LPS₂₁, and LPS₂₂ have such a curved shape that is obtainable from a planar surface by bending about only one axis, and the radius of curvature is constant. Naturally, when forming the plate, a planar plate may be bent in multiple process steps, but the resulting plate has a shape of being bent about only one axis such that the resulting radius of curvature is constant. Preferably, the first primary lamella plate surface LPS₁₁ and second primary lamella plate surface LPS₂₁, are either planar or curved surfaces in such a way that they are obtainable from a planar surface by bending about only one axis or axes that are parallel with each other. With reference to FIGS. 20a and 20b, the first primary lamella plate surface LPS₁₁ and second primary lamella plate surface LPS₂₁ may be planar even if the whole surfaces 510, 520 are not.

[0054] The surfaces 510, 520 having both a protrusion and an indentation has the effect that the walls of the sipe manufactured by the lamella plate 500 lock to each other well irrespective of the direction of the forces (forward or backward; or transversal forces to left or right). Correspondingly, the sipes function well both during acceleration and braking, and improve handling also when driving on a curve, curved to either direction.

[0055] In an embodiment, a thickness of the lamella plate 500 is constant at least in the regions defining the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁. This has the effect that the second primary plate protrusion PP₂₁, which is opposite to the first primary plate indentation PI₁₁, is geometrically congruent with the first primary plate indentation PI₁₁. Moreover, the second primary plate indentation PI₂₁, which is opposite to the first primary plate protrusion PP₁₁, is geometrically congruent with the first primary plate protrusion PP₁₁. This improves the locking of the sipe walls to each other. More preferably, a thickness of the lamella plate 500 is constant at least in the regions defining the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, the second primary plate indentation PI₂₁, the first primary lamella plate surface LPS₁₁, and the second primary lamella plate surface LPS₂₁. Naturally, the thickness of the whole lamella plate 500 may be constant. This is beneficial for manufacturing reasons. The thickness of the lamella plate 500 may be e.g. 0.2 mm to 3.0 mm; preferably 0.3 mm to 1.2 mm.

[0056] It has been found that the locking functions particularly well when the first primary plate indentation PI₁₁ is arranged close to the first primary plate protrusion PP₁₁. They may even contact each other, as shown in FIG. 2c. Therefore, in an embodiment, a minimum distance d_PI between the first primary plate protrusion PP₁₁ and the first primary plate indentation PI₁₁ is at most 4 mm. The minimum distance d_PI is preferably at most equal to a thickness of the lamella plate 500. The minimum distance d_PI may be at most 2 mm or zero. These distances have the effect that the projection functions together with the closely neighbouring indentation in this way improving the locking effect. In an embodiment, the minimum distance d_PI is arranged in a direction that is parallel to a projection line PR. The projection line PR is a projection of a of a line that remains between a centre of the first primary plate protrusion PP₁₁ and a centre of the first primary plate indentation PI₁₁, the projection being a normal projection to the first primary lamella plate surface LPS₁₁. Such a projection line PR is shown e.g. in FIG. 4a. The minimum distance d_PI may be zero as in FIG. 2c. However, the protrusion PP₁₁ and the indentation PI₁₁ need not contact each other, whereby the distance may be greater, as shown in FIG. 2e. It is noted that FIG. 2e shows a protrusion and an indentation that do not incline towards each other, as detailed below. A somewhat similar shape is shown also in FIGS. 10a and 10b.

[0057] Referring to FIGS. 2b, 2c, and 2d, preferably, the first primary plate protrusion PP₁₁ is symmetric with the second primary plate protrusion PP₂₁ about an axis AXs. More precisely, in an embodiment, the first primary plate protrusion PP₁₁ is symmetric with the second primary plate protrusion PP₂₁ about an axis AXs such that, upon a rotation of 180 degrees about the axis AXs of symmetry, the first primary plate protrusion PP₁₁ coincides with the second primary plate protrusion PP₂₁ (unrotated). Herein the angle of 180 degrees is given with an accuracy of only two significant figures, because the curved surface (see FIGS. 11a to 11c) may have the effect that the angle is not precisely 180 degrees. Having this type of symmetry in the lamella plate 500 relates to the effect of locking the sipes in all directions that are parallel to the tread 110.

[0058] In case the first primary plate protrusion PP₁₁ is symmetric with the second primary plate protrusion PP₂₁ about an axis AXs, preferably, the axis AXs of symmetry is parallel or at least substantially parallel to a direction that, in the tire, is a radial direction. More specifically, preferably, [i] a direction of the axis AXs is parallel to a direction d_R that is directed from a lower edge 530 of the lamella plate 500 to an opposite upper edge 540 (see FIG. 2b) or [ii] a direction of the axis AXs forms first angles (α₁, α₂) with a direction d_R that is directed from a lower edge 530 of the lamella plate 500 to an opposite upper edge, wherein a minimum α₁ of the first angles (α₁, α₂) is at most 30 degrees (see FIG. 2d). The direction d_R is directed from the lower edge 530 of the lamella plate 500 to the opposite upper edge 540 along shortest possible path. A hole 550 may be arranged closer to the upper edge 540 than the lower edge 530 (see FIG. 22).

[0059] As for other characteristics of preferable shapes for the indentation PI₁₁ and protrusion PP₁₁, it is noted that the first primary plate protrusion PP₁₁ and the first primary plate indentation PI₁₁ define a projection line PR (see FIG. 4a) as defined above.

[0060] Preferably, the indentation PI₁₁ and protrusion PP₁₁ are arranged side-by-side rather than on top of each other. This improves handling of the tire under transversal load, e.g. driving in a curve. Referring to FIG. 4a, preferably, a direction of the projection line PR forms second angles β₁, β₂ with the direction d_R, wherein a minimum β₁ of the second angles β₁, β₂ is at least 60 degrees. Referring to FIG. 4a, the minimum β₁ of the second angles β₁, β₂ may be 90 degrees (one significant figure).

[0061] Referring to FIG. 4a, in a preferable embodiment, the first primary plate protrusion PP₁₁ is antisymmetric about all such planes L_AS that have a normal that is parallel to the projection line PR. In other words, the first primary plate protrusion PP₁₁ is not symmetric about any such plane L_AS that has a normal that is parallel to the projection line PR. It has been found that this improves handling of the tire under transversal load, e.g. driving in a curve. For similar reasons, in an embodiment, the first primary plate indentation PI₁₁ is antisymmetric about all such planes L_AS that have a normal that is parallel to the projection line PR.

[0062] Referring to FIG. 4b, in an embodiment, the first primary plate protrusion PP₁₁ is symmetric about a plane L_S. As shown in FIG. 4b, a normal of the plane L_S of symmetry may be parallel to the direction d_R as defined above. However, it need not be parallel, as shown in FIG. 2d. In an embodiment, the first primary plate indentation PI₁₁ is symmetric about a plane. It may be symmetric about the same plane L_S. This type of symmetry has the effect that an outer part of the tread locks to a neighbouring sipe as well as an inner part of the tread. This has beneficial properties for handling the tire. More preferably, the first primary plate protrusion PP₁₁ is symmetric about a plane L_S and the first primary plate indentation PI₁₁ is symmetric about the plane L_S. The plane L_S of symmetry may comprise the projection line PR as defined above and a normal of the primary lamella plate surface LPS₁₁ as defined above.

[0063] It has also been found that the locking improves when there is a smooth transition from the protruding region of the first surface 510 to the declining region of the first surface 510. Therefore, and with reference to FIG. 5a, in an embodiment a part of a surface of the first primary plate protrusion PP₁₁ is inclined such that a height hP₁₁(r) of the first primary plate protrusion PP₁₁, measured from the first primary lamella plate surface LPS₁₁, decreases towards the first primary plate indentation PI₁₁. Herein the height hP₁₁(r) refers to the height as measured in a location r. Thus, the height hP₁₁(r) decreases as the location r moves towards the first primary plate indentation PI₁₁ as shown in FIG. 5a. In contrast, the height hP₁₁(r) could decrease to zero abruptly (within the limits of manufacturing tolerances of the lamella plate 500) as indicated in FIGS. 2e and 10b. A maximum of the height hP₁₁(r) of the first primary plate protrusion PP₁₁ is, in an embodiment, from 0.5 mm to 4 mm.

[0064] When the height hP₁₁(r) of the first primary plate protrusion PP₁₁ decreases towards the first primary plate indentation PI₁₁ the height hP₁₁(r) preferably decreases such that a first inclination IN1 (see FIGS. 5b and 5c) defines a first inclination angle γ1 less than 45 degrees. The first inclination angle γ1 is an angle that remains between (i) a primary first line that remains between the point r of maximum height of the height hP₁₁(r) of the first primary plate protrusion PP₁₁ and a center of the projection line PR as defined above and (ii) a secondary first line that is projection of the primary first line, the projection being a normal projection to the first primary lamella plate surface LPS₁₁. Reference is made to FIG. 5c. It has been found that if the first inclination angle γ1 was more, the locking effect would not be as good. Clearly, by the nature of the protrusion, the first inclination angle γ1 is greater than zero. Preferably, the first inclination angle γ1 is at least 2 degrees. The first inclination angle γ1 is shown in FIG. 5b.

[0065] As for an abrupt decrement of the height, an abrupt decrement can be quantified by a third inclination angle (not shown), which is for the abrupt change almost 90 degrees, e.g. at least 85 degrees.

[0066] Preferably, also the inclination of different sides of the protrusion PP₁₁ makes it antisymmetric as indicated above. Thus, in a preferable embodiment (see FIG. 5c), a first part R1 of a surface of the first primary plate protrusion PP₁₁ is inclined such that a height hP₁₁(r) of the first primary plate protrusion PP₁₁ decreases from a maximal height towards the first primary plate indentation PI₁₁ by a first inclination IN1. As previously, the height hP₁₁(r) is defined from the first primary lamella plate surface LPS₁₁. Moreover, a second part R2 of the surface of the first primary plate protrusion PP₁₁ is inclined such that the height hP₁₁(r) of the first primary plate protrusion PP₁₁ decreases from the maximal height away from the first primary plate indentation PI₁₁ by a second inclination IN2. Moreover, the second inclination IN2 is different from the first inclination IN1. Preferably, the second inclination IN2 is steeper than the first inclination IN1, as depicted in FIG. 5c. This applies also to the second primary plate protrusion PP₂₁ mutatis mutandis (see FIG. 2c).

[0067] The second inclination IN2 defines a defines a second inclination angle γ2. The second inclination angle γ2 is an angle that remains between (i) a primary second line that remains between the point r of maximum height of the height hP₁₁(r) of the first primary plate protrusion PP₁₁ and a point that is on a line that comprises the projection line PR the point being located at such a boundary of the first primary plate protrusion PP₁₁ that is opposite to a center of the projection line PR and (ii) a secondary second line that is projection of the primary second line, the projection being a normal projection to the first primary lamella plate surface LPS₁₁. Reference is made to FIG. 5c. Preferably, the second inclination angle γ2 is greater than the first inclination angle γ1. Preferably, also the second inclination is not abrupt. Thus, preferably, the second inclination angle γ2 is less than 85 degrees. The second inclination angle γ2 is shown in FIG. 5b.

[0068] Preferably a height of the lamella plate (i.e. a distance between the lower edge 530 and the upper edge 540) is more or less constant at least for the part that comprises the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁. However, in case the lamella plate is for manufacturing a sipe for a shoulder are of the tire, the height of the lamella plate at one end may be less that the height of the lamella plate at another, opposite, end.

[0069] The height of the lamella plate 500 may decrease locally e.g. because of a taper 532 (see FIG. 6b). Such a taper may be arranged according to needs. A taper 532 may, e.g., ease bending of a plate. In a preferable embodiment, the lower edge 530 extends without a taper 532 for at least a portion overlapping each one of the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁. Herein the term overlapping refers to overlapping in the direction d_R as defined above. Moreover, the lower edge 530 is configured to be inserted into a tread 110 of a tire 100, while typically the opposite upper edge 540 is not configured to be inserted in to the tread at all. As two examples, the neither the taper 532 of FIG. 20a nor the taper 532 of FIG. 19 overlaps any protrusion or indentation in the direction d_R.

[0070] Herein the term “taper” refers to a groove limited by the lamella plate, the groove extending in the thickness of the lamella plate. Thus, the taper tapers the lamella plate, i.e. reduces locally its height.

[0071] The lamella plate 500 may also comprise a taper 532, e.g. when it has more protrusions. Referring to FIGS. 6b, 8a, 11a, and 20a, in an embodiment the lower edge 530 comprises a taper 532. However as shown in the figures, preferably the taper 532 does not overlap any one of the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁. Referring to FIG. 6b, preferably, a length L_ftb of the portion of the lower edge 530 that is free from a taper 532 is at most 50% greater than a length L_ppi of projection of the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁ to the lower edge 530. The lengths L_ppi and L_ftb may be substantially equal, as readable from FIG. 7a.

[0072] Preferably, at least a part of the first primary lamella plate surface LPS₁₁ is arranged between the upper edge 540 of the lamella plate 500 and both of the first primary plate indentation PI₁₁ and the first primary plate protrusion PP₁₁. This has the effect that a reasonably large portion of a wall of a sipe that is the outermost part of the tread has the shape of a plane or a curved surface. This improves traction of the tire, sine the edges of such sipes have an improved grip on the road.

[0073] Preferably, also at least a part of the first primary lamella plate surface LPS₁₁ is arranged between the lower edge 530 and both of the first primary plate indentation PI₁₁ and the first primary plate protrusion PP₁₁.

[0074] The projection line PR as defined above defines a direction SS of a length of the lamella plate 500, at least at the location of the projection PR line. Referring to FIG. 4a, in an embodiment, a length RPI₁₁ of the first primary plate indentation PI₁₁, as measured in the direction SS of a length of the lamella plate 500 is greater than a width WPI₁₁ of the first primary plate indentation PI₁₁, as measured in a direction that is perpendicular to the direction SS of the length of the lamella plate and perpendicular to a norm of the first primary lamella plate surface LPS₁₁. This has the effect that the first primary plate indentation PI₁₁ can be made relatively large, which improves the locking of the sipe walls. Preferably, the length RPI₁₁ of the first primary plate indentation PI₁₁ is at least 5% greater than the width WPI₁₁ of the first primary plate indentation PI₁₁. This applies also to the first primary plate indentation PP₁₁. Thus, in an embodiment, a length RPP₁₁ of the first primary plate protrusion PP₁ is greater than a width WPP₁₁ of the first primary plate protrusion PI₁₁, wherein the direction of length and width are defined as in the context of the indentation PI₁₁. Preferably, the length RPP₁₁ of the first primary plate protrusion PP₁₁ is at least 5% greater than the width WPP₁₁ of the first primary plate protrusion PP₁₁.

[0075] In an embodiment, the length RPI₁₁ of the first primary plate indentation PI₁₁ is from 1.5 mm to 20 mm, such as from 2.5 mm to 15 mm. In an embodiment, the length RPP₁₁ of the first primary plate protrusion PP₁₁ is from 1.5 mm to 20 mm, such as from 2.5 mm to 15 mm. In an embodiment, the length RPP₁₁ of the first primary plate protrusion PP₁₁ is equal to the length RPI₁₁ of the first primary plate indentation PI₁₁. In an embodiment, the width WPP₁₁ of the first primary plate protrusion PP₁₁ is equal to the width WPI₁₁ of the first primary plate indentation PI₁₁.

[0076] In an embodiment, a maximum of the width WPI₁₁ of the first primary plate indentation PI₁₁ is from 1.5 mm to 15 mm. In an embodiment, a maximum of the width WPP₁₁ of the first primary plate protrusion PP₁₁ is from 1.5 mm to 15 mm.

[0077] As for the width WPI₁₁ of the first primary plate indentation PI₁₁, preferably the first primary plate indentation PI₁₁ is narrower closer to the protrusion PP₁₁ than away from it. More specifically, and referring to FIGS. 12a and 12b, in an embodiment, the width WPI₁₁(r) of the primary plate indentation PI₁₁ decreases towards the first primary plate protrusion PP₁₁. Referring to FIG. 12b, the width WPI₁₁(r₁) of the first primary plate indentation PI₁₁ at a first location r₁, which is further away from the first primary plate protrusion PP₁₁ than a second location r₂, is greater than the width WPI₁₁(r₂) of the primary plate indentation PI₁₁ at the second location r₂.

[0078] In an embodiment, this applies also to the first primary plate protrusion PP₁₁ mutatis mutandis. Thus, in an embodiment, a width WPP₁₁(r) of the primary plate protrusion PP₁₁ decreases towards the first primary plate indentation PI₁₁. Referring to FIG. 12b, the width WPP₁₁(r₃) of the first primary plate protrusion PP₁₁ at a third location r₃, which is further away from the first primary plate indentation PI₁₁ than a fourth location r₄, is greater than the width WPP₁₁(r₄) of the first primary plate protrusion PP₁₁ at the fourth location r₄.

[0079] Referring to FIGS. 6c, 7a to 7c, and 20a and 20b, the whole lamella plate 500, excluding the protrusions and the indentations, need not have a shape of a plane or a curved surface. As indicated in FIGS. 6c, 7a, 20a, and 20b, the lamella plate 500 may comprise multiple bend points BP. In this case, the first primary lamella plate surface LPS₁₁ and the first secondary lamella plate surface LPS₁₂ may be arranged between two neighbouring bend points, and the protrusions PP₁₁, PP₂₁ may protrude therefrom and the indentations PI₁₁, PI₂₁ may descend thereto, as indicated in FIGS. 7a and 20a. Moreover, lengthwise, the protrusions PP₁₁, PP₂₁ and the indentations PI₁₁, PI₂₁ may use the whole length between the bend points BP. However, they need not. In this sense, the bend point BP may affect the length of the lower edge 530 in a similar way as a taper 532. Reference is made also to FIG. 6b and what has been said about the length of the lower edge 530. Thus, in an embodiment the lower edge 530 comprises a bend point BP. However, preferably the bend point BP does not overlap any one of the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁. Preferably, a length L_ftb of the portion of the lower edge 530 that is free from a bend point BP is at most 50% greater than a length L_ppi of projection of the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁ to the lower edge 530. The lengths L_ppi and L_ftb may be substantially equal.

[0080] In particular, if the lower edge 530 comprises bend points BP, it may comprise a taper 532 that overlaps the first primary plate indentation PI₁₁ or the first primary plate protrusion PP₁₁. Even in such a case, a length L_ftb of the portion of the lower edge 530 that is free from a bend point BP is, in an embodiment, at most 50% greater than a length L_ppi of projection of the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁ to the lower edge 530. The lengths L_ppi and L_ftb may be substantially equal.

[0081] As indicated in FIGS. 7a and 7b, not even a part of the first primary lamella plate surface LPS₁₁ or the first secondary lamella plate surface LPS₁₂ needs to be arranged in between a bend point BP and a the protrusion PP₁₁ or the indentation PI₁₁. As indicated in FIGS. 7a and 7c, in such a case, at least a part of the first primary lamella plate surface LPS₁₁ may be arranged between the upper edge 540 and the protrusion/indentation and/or between the lower edge 530 and the protrusion/indentation.

[0082] Referring to FIGS. 6a-6c and 8a to 20b, the lamella plate 500 may comprise another protrusion and indentation. Thus, in an embodiment, the first surface 510 is provided with a first secondary plate indentation PI₁₂ and a first secondary plate protrusion PP₁₂. Correspondingly, the second surface 520 is provided with a second secondary plate protrusion PP₂₂ that is opposite to the first secondary plate indentation PI₁₂ and a second secondary plate indentation PI₂₂ that is opposite to the first secondary plate protrusion PP₁₂ (see FIG. 6c).

[0083] Moreover, the first surface 510 defines a first secondary lamella plate surface LPS₁₂ having the shape of a planar surface or a curved surface, from which the first secondary plate protrusion PP₁₂ protrudes and into which the first secondary plate indentation PI₁₂ descends. In addition, the second surface 520 defines a second secondary lamella plate surface LPS₂₂ having the shape of a planar surface or a curved surface, from which the second secondary plate protrusion PP₂₂ protrudes and into which the second secondary plate indentation PI₂₂ descends. What has been said about the area of the primary lamella plate surface LPS₁₁ applies, mutatis mutandis, to an area of the first secondary lamella plate surface LPS₁₂.

[0084] Referring to FIGS. 6a, 6b and 8a to 19, both the first primary lamella plate surface LPS₁₁ and the first secondary lamella plate surface LPS₁₂ may be a part of the same planar or curved surface. In a similar manner, both the second primary lamella plate surface LPS₂₁ and second secondary lamella plate surface LPS₂₂ may be a part of the same planar or curved surface. However, referring to FIGS. 6c and 20b, they need not be. In the embodiment of FIG. 6c, the lamella plate 500 comprises such bend points that the first primary lamella plate surface LPS₁₁ and the first secondary lamella plate surface LPS₁₂ are not part of the same curved surface in the conventional meaning of the term “curved surface”. For a detailed definition of a curved surface, see above wherein the term is defined in connection with the first primary lamella plate surface LPS₁₁ and second primary lamella plate surface LPS₂₁. In the embodiment of FIG. 20b, the lamella plate 500 comprises such bend points that the first primary lamella plate surface LPS₁₁ and the first secondary lamella plate surface LPS₁₂ are planar, but not part of the same plane.

[0085] The embodiment of FIG. 6b shows a taper 532 that is arranged at a location L₁₂. The embodiment of FIG. 6b shows a bend point BP that is arranged at a location L₁₂. As indicated in these figures, the location L₁₂ of the taper 532 or bend point BP does not overlap a protrusion or an indentation in the meaning discussed above. In contrast, the location L₁₂ of the bend point BP or the taper 532 is arranged between [A] that one of the first secondary plate indentation PI₁₂ and the first secondary plate protrusion PP₁₂ that is closer to the first primary plate indentation PI₁₁ and [B] that one of the first primary plate indentation PI₁₁ and the first primary plate protrusion PP₁₁ that is closer to the first secondary plate indentation PI₁₂. However, in addition, the plate may comprise taper that overlaps a protrusion or an indentation in the meaning discussed above. However, preferably, a lamella plate does not comprise a taper that would overlap a protrusion or an indentation in the meaning discussed above.

[0086] Referring to FIG. 13, if the lamella plate comprises multiple protrusions/indentations, they are preferably arranged such that a direction of a line L_LP12 that runs (i) from a centre of a locking form defined by the first primary plate indentation PI₁₁ and a first primary plate protrusion PP₁₁ (ii) to a centre of a locking form defined by the first secondary plate indentation PI₁₂ and the first secondary plate protrusion PP₁₂ is substantially parallel to such a part of the lower edge 530 of the lamella plate 500 that comprises neither a taper 532 nor a bend point BP. In other words, the locking forms are preferably not arranged on top of each other in the direction that would be radial in the corresponding tire. The line L_LP12 may be parallel to the such a part of the lower edge 530 of the lamella plate 500 that comprises neither a taper 532 nor a bend point BP. In an embodiment, the smaller of the angles formed by the line L_LP12 with such a part of the lower edge 530 of the lamella plate 500 that comprises neither a taper 532 nor a bend point BP is at most 10 degrees.

[0087] Moreover, preferably the protrusions PP₁₁, PP₁₂ and the indentations PI₁₁ and PI₁₂ are arranged subsequently such that a protrusion is only arranged between two indentations and vice versa as in the Figures. Therefore, in an embodiment, [i] provided that a distance between the first primary plate indentation PI₁₁ and the first secondary plate indentation PI₁₂ is smaller than a distance between the first primary plate protrusion PP₁₁ and the first secondary plate indentation PI₁₂, a distance between the first primary plate indentation PI₁₁ and the first secondary plate protrusion PP₁₂ is smaller than a distance between the first primary plate indentation PI₁₁ and the first secondary plate indentation PI₁₂, and [ii] otherwise, a distance between the first primary plate protrusion PP₁₁ and the first secondary plate indentation PI₁₂ is smaller than a distance between the first primary plate protrusion PP₁₁ and the first secondary plate protrusion PP₁₂. However, the protrusions PP₁₁ and PP₁₂ may be arranged without any indentation in between them and/or the indentations PI₁₁ and PI₁₂ may be arranged without any protrusion in between them (not shown).

[0088] The lamella plate 500 as described above may be used to form a sipe of a tire 100. Multiple lamella plates may be used to form multiple sipes to a tread block or a sipe to multiple tread blocks or multiple sipes to multiple tread blocks, which is the most common way for making the sipes.

[0089] FIG. 1a shows a tire 100 comprising a tread 110. The tread 110 is formed of multiple tread blocks forming an arrangement 200 of tread blocks. The tire 100 is configured to form a rolling contact against a base 900 such as a road. Referring to FIG. 1b the arrangement 200 of tread blocks comprises a first tread block TB₁ and a second tread block TB₂. In general, the tread blocks define a groove 120 (and also other grooves) which are configured to guide water and slush away from a contact area of the tire 100. Thus, the first tread block TB₁ is separated from the second tread block TB₂ (and another tread block TB₃, TB₄) by a portion of the groove 120. FIG. 1c shows half of a cross section of a tire 100 and indicates the radial direction SR and the axial direction, i.e. the transversal direction (AX, ST) of the tire. The axial direction AX forms an axis of rotation of the tire 100.

[0090] The tread of the tire is formed of multiple tread blocks, including a first tread block TB₁ and a second tread block TB₂. Each tread block may comprise a number of sipes, such as a primary sipe and a secondary sipe. Thus e.g. a first tread block TB₁ may limit a primary first sipe S₁₁ and a secondary first sipe S₂₁, the “first” referring to an index of the tread block. Moreover, a (primary, secondary, etc.) sipe is arranged between two walls, the walls being comprised by the (first, second, etc.) tread block. These walls are called as first and second walls. When they concern e.g. a primary first sipe S₁₁, they are called a first primary first wall W₁₁₁ and a second primary first wall W₂₁₁.

[0091] Thus, referring to FIGS. 1b and 3a, the first tread block TB₁ is provided with sipes, including a primary first sipe S₁₁. The first tread block TB₁ may also limit a secondary first sipe S₂₁. A lamella LAM is arranged in between the sipes S₁₁ and S₂₁. The sipes are limited by side walls. Particularly, the primary first sipe S₁₁ is limited by a first primary first wall W₁₁₁ and an opposite second primary first wall W₂₁₁ as indicated in FIG. 3b. These walls are provided in the first tread block TB₁. As readable from above, the walls W₁₁₁ and W₂₁₁ have been made by a lamella plate 500 as detailed above. Referring to FIGS. 2c and 3d, the first primary first wall W₁₁₁ may have been made by the first surface 510 of a lamella plate 500. Correspondingly, referring to FIGS. 2c and 3c, the second primary first wall W₂₁₁ may have been made by the second surface 520 of a lamella plate 500. Moreover, outside the location of a lamella plate, the tread block may be integral (i.e. without a sipe). This is shown by the text “no sipe here” in FIG. 22. As indicated in FIG. 22, in use, an upper edge 540 of a lamella plate 500 may protrude from the tread 110 partly formed by the tread block TB₁. Moreover, a lamella plate 500 may be provided with holes 550 close to the upper edge 540 to help the removal of the lamella plate from the tread 110. Such holes are also shown in FIG. 20a. Also other embodiments of lamella plates may comprise similar holes 550.

[0092] Therefore, referring to FIG. 3b, the first tread block TB₁ comprises a first primary first wall W₁₁₁ and a second primary first wall W₂₁₁ such that a primary first sipe S₁₁ is arranged between the first primary first wall W₁₁₁ and the second primary first wall W₂₁₁. Because of the shape of the lamella plate 500, the first primary first wall W₁₁₁ is provided with a first primary first wall indentation WI₁₁₁ and first primary first wall protrusion WP₁₁₁ as shown in FIG. 3d. These correspond to the first primary plate protrusion PP₁₁ and the first primary plate indentation PI₁₁ of the lamella plate 500, respectively (see FIGS. 3d and 2c). Moreover, the second primary first wall W₂₁₁ is provided with a second primary first wall indentation WI₂₁₁ and second primary first wall protrusion WP₂₁₁. These correspond to the second primary plate protrusion PP₂₁ and the second primary plate indentation PI₂₁ of the lamella plate 500, respectively (see FIGS. 3c and 2c).

[0093] Moreover, the first primary first wall W₁₁₁ comprises (i.e. defines) a first primary first wall surface WS₁₁₁ having the shape of a planar surface or a curved surface, from which the first primary first wall protrusion WP₁₁₁ protrudes and into which the first primary first wall indentation WI₁₁₁ descends (see FIGS. 3d and 22). This corresponds to the first primary lamella plate surface LPS₁₁ of the lamella plate 500. The second primary first wall W₂₁₁ comprises (i.e. defines) a second primary first wall surface WS₂₁₁ having the shape of a planar surface or a curved surface, from which the second primary first wall protrusion WP₂₁₁ protrudes and into which the second primary first wall indentation WI₂₁₁ descends (see FIG. 3c). This corresponds the second primary lamella plate surface LPS₂₁ of the lamella plate 500.

[0094] Moreover, to provide for the locking of the walls W₁₁₁, W₂₁₁ together during braking or acceleration or driving on a curve, the first primary first wall indentation WI₁₁₁ is geometrically congruent with the second primary first wall protrusion WP₂₁₁ and the first primary first wall protrusion WP₁₁₁ is geometrically congruent with the second primary first wall indentation WI₂₁₁. They are also arranged such that upon compressing the first primary first wall W₁₁₁ and the second primary first wall W₂₁₁ to each other, the second primary first wall protrusion WP₂₁₁ penetrates into the first primary first wall W₁₁₁; and the first primary first wall protrusion WP₁₁₁ penetrates into the second primary first wall indentation WI₂₁₁. This can be achieved at least when a thickness of the lamella plate 500 is constant at least in the regions defining the first primary plate indentation PI₁₁, the first primary plate protrusion PP₁₁, the second primary plate protrusion PP₂₁, and the second primary plate indentation PI₂₁; as discussed above.

[0095] As for the term sipe, a width of the sipe corresponds to a thickness of the lamella plate 500. Therefore, in an embodiment, a width of the primary first sipe S₁₁ is from 0.2 mm to 3.0 mm, preferably from 0.3 mm to 1.2 mm. A readable from FIG. 3b, the width of the primary first sipe S₁₁ remains between the first primary first wall W₁₁₁ and the second primary first wall W₂₁₁.

[0096] As indicated in connection with the lamella plate, in an embodiment, a minimum distance between the first primary first wall indentation WI₁₁₁ and the first primary first wall protrusion WP₁₁₁ is at most 4 mm. This corresponds the distance d_PI of the lamella plate (see FIGS. 2c and 2e). The minimum distance between the first primary first wall indentation WI₁₁₁ and the first primary first wall protrusion WP₁₁₁ may be e.g. at most equal the width of the primary first sipe S₁₁, such as at most 2 mm or zero; i.e. the protrusion WP₁₁₁ may start at a location where the indentation WI₁₁₁ ends.

[0097] As indicated in connection with the lamella plate, therein the first primary plate protrusion PP₁₁ may be symmetric with the second primary plate protrusion PP₂₁ about an axis AXs. If so, this shows also in the walls W₁₁₁, W₂₁₁ of the first tread block TB₁. Thus and with reference to FIG. 21, in an embodiment, a first form FWP that is symmetric with the first primary first wall protrusion WP₁₁₁ about a first symmetry plane SP₁ is symmetric with the first primary first wall indentation WI₁₁₁ about a second symmetry plane SP₂, the second symmetry plane SP₂ being perpendicular to the first symmetry plane SP₁. The first symmetry plane SP₁ intersects the second symmetry plane SP₂. The intersection of these planes forms a line, which is parallel to the axis AXs; at least when a part of the lamella plate 500 has been inserted into the tread to form the wall protrusions and indentations as detailed above.

[0098] Referring to FIG. 22, the first primary first wall protrusion WP₁₁₁ the first primary first wall indentation WI₁₁₁ of the first primary first wall W₁₁₁ define a projection line PR_W on the wall (i.e. a wall projection line PR_W), the projection line PR_W on the wall being a projection of a line that remains in between a centre of the first primary first wall protrusion WP₁₁₁ and a centre of the first primary first wall indentation WI₁₁₁, the projection being a normal projection to the first primary first wall surface WS₁₁₁.

[0099] As shown in FIG. 22, the first primary wall W₁₁₁ is a wall of the first tread block TB₁, which defines a part of the tread 110 (see FIGS. 1 and 2). Referring to FIG. 22, in an embodiment, the projection line PR_W on the wall is parallel to the tread 110. However, it need not be. Considering FIG. 2d and its effects on the tire 100, in an embodiment, the projection line PR_W on the wall forms a minimum angle with the tread 110, and the minimum angle is at most 30 degrees. This relates to the angle α₁ defined above. It is noted that the tread 110 is a surface, and, as conventional, an angle between a line (e.g. PR_W) with a plane is defined as the minimum angle between these.

[0100] As indicated in connection with the lamella plate, in an embodiment, the first primary first wall protrusion WP₁₁₁ is antisymmetric about all such planes W_AS that have a normal that is parallel to the projection line PR_W on the wall (i.e. the wall projection line PR_W) as defined above. Reference is made to FIG. 22. This may apply also to the primary first wall indentation WI₁₁₁ mutatis mutandis. Therefore, in an embodiment, the first primary first wall indentation WI₁₁₁ is antisymmetric about all such planes W_AS that have a normal that is parallel to the projection line PR_W on the wall (i.e. the wall projection line PR_W) as defined above.

[0101] Referring still to FIG. 22, in an embodiment, the first primary first wall protrusion WP₁₁₁ is symmetric about a plane. In an embodiment, the first primary first wall indentation WI₁₁₁ is symmetric about another plane or the same plane. In an embodiment, both the first primary first wall protrusion WP₁₁₁ and the first primary first wall indentation WI₁₁₁ are symmetric about a plane. Referring to FIG. 22, the plane of symmetry may comprise the wall projection line PR_W. The plane of symmetry is not shown in FIG. 22; instead, reference is made to FIG. 4b and the plane L_S.

[0102] Referring particularly to FIG. 5c, the first primary plate protrusion PP₁₁ may comprise inclined areas. This concerns also the indentations PI₁₁, PI₂₁ of the lamella plate and, correspondingly, the protrusion PP₂₁ the lamella plate (see FIG. 5c) mutatis mutandis.

[0103] This shows also in the protrusions/indentations of the tire, as reproduced in FIG. 23. Referring to FIG. 23, in an embodiment, a part of a surface of the first primary first wall protrusion WP₁₁₁ is inclined such that a height hWP₁₁₁(r) of the first primary first wall protrusion WP₁₁₁, measured from the first primary first wall surface WS₁₁₁, decreases towards the first primary first wall indentation WI₁₁₁. A maximum of the height hWP₁₁₁(r) of the first primary first wall protrusion WP₁₁₁ is, in an embodiment, from 0.5 mm to 4.0 mm. Correspondingly, a maximum of a depth of the first primary first wall indentation WI₁₁₁ is, in an embodiment, from 0.5 mm to 4.0 mm. The depth is defined from the first primary first wall surface WS₁₁₁.

[0104] More preferably, a first part of a surface of the first primary wall protrusion WP₁₁₁ is inclined such that a height hWP₁₁₁(r) of the first primary wall protrusion WP₁₁₁, measured from the first primary first wall surface WS₁₁₁, decreases from a maximal height towards the first primary first wall indentation WI₁₁₁ by a third inclination. In addition, a second part of a surface of the first primary wall protrusion WP₁₁₁ is inclined such that a height hWP₁₁₁(r) of the first primary wall protrusion WP₁₁₁, measured from the first primary first wall surface WS₁₁₁, decreases from a maximal height away from the first primary first wall indentation WI₁₁₁ by a fourth inclination, wherein the fourth inclination is different from the third inclination. Even more preferably, the fourth inclination is steeper than the third inclination, as depicted in FIG. 23. This applies also to the second primary first wall protrusion WP₂₁₁ of the other wall W₂₁₁ of the sipe mutatis mutandis.

[0105] As readable from above, in an embodiment, the third inclination corresponds to the first inclination IN1 of the lamella plate 500. In an embodiment, the fourth inclination corresponds to the second inclination IN2 of the lamella plate 500. Thus, an inclination angle of the third inclination may be 2 to 45 degrees as disclosed in connection with the lamella plate and the first inclination angle γ1. Moreover, an inclination angle of the fourth inclination may be greater than the inclination angle of the third inclination and less than 85 degrees as disclosed in connection with the lamella plate and the second inclination angle γ2. What has been said about the definition of the inclination angles γ1 and γ2 in connection with the lamella plate 500 applies to inclination angles of the walls of the sipe mutatis mutandis.

[0106] As for preferable measures of the wall protrusion/indentation, in an embodiment and with reference to FIG. 22, a length LWP₁₁₁ of the first primary first wall protrusion WP₁₁₁, as measured in the direction of wall projection line PR_W is greater than a width of the first primary first wall protrusion WP₁₁₁. The width is defined in a direction that is perpendicular to the direction of wall projection line PR_W and perpendicular to a norm of the first primary first wall surface WS₁₁₁. In FIG. 22, the width would be defined in the direction SR which is perpendicular to the tread 110. However, the wall projection line PR_W needs not be parallel to the tread 110.

[0107] In an embodiment, the length LWP₁₁₁ of the first primary first wall protrusion WP₁₁₁ is from 1.5 mm to 20 mm, such as from 2.5 mm to 15 mm. Preferably, the length LWP₁₁₁ of the first primary first wall protrusion WP₁₁₁ is at least 5% greater than the width of the first primary first wall protrusion WP₁₁₁.

[0108] Preferably, a width of the first wall protrusion WP₁₁₁ decreases towards the first primary first wall indentation WI₁₁₁, the width of the first wall protrusion WP₁₁₁ being perpendicular to the length of the first wall protrusion WP₁₁₁. Preferably, a width of the first wall indentation WI₁₁₁ decreases towards the first primary first wall protrusion WP₁₁₁, the width of the first wall indentation WI₁₁₁ being perpendicular to the length of the first wall indentation WI₁₁₁.

[0109] A maximum of the width of the first wall protrusion WP₁₁₁ may be 1.5 mm to 15 mm. A maximum of the width of the first wall indentation WI₁₁₁ may be 1.5 mm to 15 mm.

[0110] As indicated above, the first primary first wall W₁₁₁ is configured to lock with the second primary first wall W₂₁₁. To this end, the protrusion and indentation, in combination, define a locking shape to enable the locking. More precisely, the first primary first wall indentation WI₁₁₁ and the first primary first wall protrusion WP₁₁₁ form a first locking form, which is arranged on the first primary first wall W₁₁₁; and the second primary first wall protrusion WP₂₁₁ and the second primary first wall indentation WI₂₁₁ form a second locking form, which is arranged on the second primary first wall W₂₁₁. The second locking form is geometrically congruent with the first locking form to enable a shape-locking mechanism of the second locking form to the first locking form upon pressing the first primary first wall W₁₁₁ and the second primary first wall W₂₁₁ together.

[0111] As detailed in connection with a lamella plate 500, the lamella plate 500 may comprise a bend point BP or a taper 532. It is noted that the lower edge 530 of the lamella plate 500 defines a bottom of the sipe, particularly the primary first sipe S₁₁. If the lower edge 530 of the lamella plate 500 comprises a taper, the bottom of the primary first sipe S₁₁ comprises a corresponding bottom protrusion (not shown). In line with what has been said about the lamella plate 500, in an embodiment, such a part of a bottom of the primary first sipe S₁₁ that is arranged below the first and second locking forms does not comprise a bend point or a bottom protrusion. If the primary first sipe S₁₁ comprises a bend point and/or a bottom protrusion that/they is/are preferably arranged to another place than below the locking forms defined by the wall protrusions/indentations. However, such a part of a bottom of the primary first sipe S₁₁ that is arranged below the first and second locking forms may comprise a bottom protrusion, even if the first and second locking forms are arranged between two bend points.

[0112] A shape of a projection of the first locking form to the first primary first wall surface WS₁₁₁ may resemble one of the following: an infinity sign, a bowtie, a dog bone, a double ended arrow, a rectangle, and a rounded rectangle. As for the locking form of the sipe of the tire 100, this concerns the locking form formed by first primary first wall indentation WI₁₁₁ and the first primary first wall protrusion WP₁₁₁. As for the locking form of the lamella plates, this concerns the locking form formed by the first primary plate indentation PI₁₁ and the first primary plate protrusion PP₁₁.

[0113] The shape of the first and second locking forms are derivable from the shape of the indentations/protrusions of the lamella plate 500. For example, the FIGS. 2a-2e, 4a, 4b, 6a, 6b, 7a, and 8a-11c show a shape that resembles an infinity sign. FIGS. 12a and 12b show a shape that resembles a double ended arrow. FIG. 13 shows a shape that resembles both a bowtie and a double ended arrow. FIG. 14 shows a shape that resembles a dog bone. FIGS. 15 and 16 show shapes that resemble bowties. FIGS. 17 and 18 show shapes that resemble rounded rectangles. FIG. 19 shows a shape that resembles a rectangle.

[0114] However, it has been found that the shape of a rectangle does not function as well as the others. Thus, in an embodiment, a shape of a projection of the first locking form to the first primary first wall surface WS₁₁₁ does not resemble a rectangle or a rounded rectangle. As for the locking form of the sipe of the tire 100, this concerns the locking form formed by first primary first wall indentation WI₁₁₁ and the first primary first wall protrusion WP₁₁₁. As for the locking form of the lamella plates, this concerns the locking form formed by the first primary plate indentation PI₁₁ and the first primary plate protrusion PP₁₁, and the shape of the locking form as projected onto the first primary lamella plate surface (LPS₁₁). Thus, in the embodiment, a shape of a projection of the first locking form to the to the first primary first wall surface WS₁₁₁ resembles one of the following: an infinity sign, a bowtie, a dog bone, and a double ended arrow.

[0115] As discussed above, the primary first sipe S₁₁ is producible in a moulding process by using a lamella plate 500 as described above. Referring to FIG. 1b, in an embodiment, first tread block TB₁ comprises a secondary first sipe S₂₁ that is producible in a moulding process by using a lamella plate 500 as described above. Referring to FIGS. 1a and 1b, in an embodiment, the tire 100 comprises a second tread block TB₂ that comprises a primary second sipe S₁₂ that is producible in a moulding process by using a lamella plate 500 as discussed above. Referring to FIGS. 1a and 1b, in an embodiment, the second tread block TB₂ comprises a secondary second sipe S₂₂ that is producible in a moulding process by using a lamella plate 500 as discussed above.

[0116] As an example, the lamella plate may comprise at least two protrusions on each surface 510, 520, as detailed e.g. in FIGS. 8a to 20b. Corresponding walls are shown in FIGS. 24a and 24b. As detailed in FIG. 24b in an embodiment, the first primary first wall W₁₁₁, which is provided with the first primary first wall indentation WI₁₁₁ and first primary first wall protrusion WP₁₁₁, is further provided with a secondary first primary first wall indentation WI₂₁₁₁ and secondary first primary first wall protrusion WP₂₁₁₁. In general, a wall may be provided with a wall protrusion WP_ijkl wherein l is an index of the tread block, k is an index of a sipe in that tread block, j is an index (1 or 2) of a wall of that sipe, and i is an index of the protrusion. In the above only three indexes are used in case a wall is discussed only in connection with one protrusion, whereby the index i=1 has been omitted. However, there may be several protrusions/indentation on a wall, even if the figures who lamella plates with at most two locking forms. As well known, the number of tread blocks in a tire may be huge (corresponding to index 1). Typically a tread block, if comprises sipes, comprises 2 to 4 sipes, but may comprise also any other number of sipes, such as 1 to 8 (corresponding to index k). In a similar manner a wall may be provided with a wall indentation WI_ijkl.

[0117] Moreover, the first primary first wall W₁₁₁ defines a secondary first primary first wall surface WS₂₁₁₁ having the shape of a planar surface or a curved surface, from which the secondary first primary first wall protrusion WP₂₁₁₁ protrudes and into which the secondary first primary first wall indentation WI₂₁₁₁ descends (see FIG. 24b).

[0118] As detailed in FIG. 24a in an embodiment, the second primary first wall W₂₁₁, which is provided with a second primary first wall indentation WI₂₁₁ and second primary first wall protrusion WP₂₁₁, is further provided with a secondary second primary first wall indentation WI₂₂₁₁ and secondary second primary first wall protrusion WP₂₂₁₁. Moreover, the second primary first wall W₂₁₁ defines a secondary second primary first wall surface WS₂₂₁₁ having the shape of a planar surface or a curved surface, from which the secondary second primary first wall protrusion WP₂₂₁₁ protrudes and into which the secondary second primary first wall indentation WI₂₂₁₁ descends (see FIG. 24a).

[0119] Referring to FIG. 24b, when the first primary first wall W₁₁₁ comprises the secondary first primary first wall indentation WI₂₁₁₁ and the secondary first primary first wall protrusion WP₂₁₁₁, these are preferably arranged such that a direction of a line L_WP12 that runs (i) from a centre of the locking form defined by the first primary first wall indentation WI₁₁₁ and the first primary first wall protrusion WP₁₁₁(ii) to a centre of a locking form defined by the secondary first primary first wall indentation WI₂₁₁₁ and the secondary first primary first wall protrusion WP₂₁₁₁ is substantially parallel to the tread 110. In other words, the locking forms are preferably not arranged on top of each other in the radial direction SR. The line L_WP12 may be parallel to the tread 110. In an embodiment, a minimum angle formed by the line L_WP12 with respect to the tread 110 is at most 10 degrees.

[0120] This applies, mutatis mutandis, to the lamella plate 500, too, as discussed above.

[0121] In an embodiment, the first tread block TB₁ is provided with a secondary first sipe S₂₁. The secondary first sipe S₂₁ is limited by walls W₁₂₁ and W₂₂₁ of the first tread block. The wall W₁₂₁ may be provided with a wall protrusion WP₁₂₁ and a wall indentation WI₁₂₁. The wall W₂₂₁ may be provided with a wall protrusion WP₂₂₁ and a wall indentation WI₂₂₁. The walls W₁₂₁ and W₂₂₁, the wall protrusions WP₁₂₁ and WP₂₂₁ and the wall indentations W₁₂₁ and WI₂₂₁

may have been formed by a lamella plate as disclosed above.

[0122] Thus, in between the primary first sipe S₁₁ and secondary first sipe S₂₁, a narrow piece of rubber material, i.e. a lamella LAM (see FIG. 1b), is arranged. A thickness of the lamella LAM may be e.g. 1 to 10 mm. Because both the sipes S₁₁ and S₂₁ have been provided with the locking shape as discussed above, also the lamella locks to other parts of the first tread block TB₁ on both sides of the lamella. This also improves grip, stability, and handling. Such sipes are shown in FIGS. 1b and 3a.

[0123] In an embodiment, the tire comprises a second tread block TB2 is provided with a primary second S₁₂ and a secondary second sipe S₂₂ (see FIG. 1b). Both the primary second S₁₂ and a secondary second sipe S₂₂ may have been made by a lamella plate 500 as discussed above. Thus, the primary second sipe S₁₂ is limited by walls W₁₁₂ and W₂₁₂ of the second tread block TB₂. The wall W₁₁₂ may be provided with a wall protrusion WP₁₁₂ and a wall indentation WI₁₁₂. The wall W₂₁₂ may be provided with a wall protrusion WP₂₁₂ and a wall indentation WI₂₁₂. Moreover, the secondary second sipe S₂₂ is limited by walls W₁₂₂ and W₂₂₂ of the second tread block TB₂. The wall W₁₂₂ may be provided with a wall protrusion WP₁₂₂ and a wall indentation WI₁₂₂. The wall W₂₂₂ may be provided with a wall protrusion WP₂₂₂ and a wall indentation WI₂₂₂. What has been said about the wall protrusion and indentation in connection with the primary first sipe S₁₁ applies.

[0124] Thus, in between the primary second sipe S₁₂ and secondary second sipe S₂₂, a narrow piece of rubber material, i.e. a lamella, is arranged. A thickness of the lamella may be within the same range as disclosed for the lamella LAM. Because both the sipes S₁₂ and S₂₂ have been provided with the locking shape as discussed above, also the lamella locks to other parts of the second tread block TB₂ on both sides of the lamella. This also improves grip and handling. Such sipes are shown in FIG. 1b.

[0125] The sipes discussed above may be used in winter tires or in summer tires. A hardness of a tread material of a summer tire is typically in the range 60 to 72 Sh(A), i.e. hardness of measured by the Shore scale, durometer type A at the temperature 23° C.

[0126] However, sipes are preferably used in wither tires for the reason discussed above. However, in winter tires, preferably also the tread material per se is reasonably soft. A hardness of a tread material of a winter tire is typically in the range 48 to 59 Sh(A).

[0127] Therefore, in an embodiment, the tread blocks (TB₁, TB₂, TB₃, TB₄) of the tread block arrangement 200 are made of rubber having the hardness 48 to 72 Sh(A). Preferably, the tread blocks (TB₁, TB₂, TB₃, TB₄) of the tread block arrangement 200 are made of rubber having the hardness 48 to 59 Sh(A).

[0128] A tire 100 having the tread block arrangement 200 as described above, may comprise a first marking 152 (see FIG. 1a) indicative of the tire 100 being suitable for use as a winter tire. A groove pattern of a winter tire is typically such that a direction of rotation of the tire 100 is defined for driving forward. Therefore, in an embodiment, the tire 100 comprises a second marking 154 indicative of a direction of rotation of the tire when driving forward.

[0129] A groove pattern refers to a pattern formed by grooves of the tire. Like a sipe, a groove is a valley in the tread, however, a width of a groove is typically much larger than that of a sipe. Grooves define the tread blocks by separating tread blocks from each other. A groove has a depth and a width. Typically, a depth of a groove is at least 6 mm, such as at least 8 mm, such as from 6 mm to 50 mm. However, the depth needs not be constant. Moreover, near sidewalls of a tire, a depth of a groove may be very small. In fact, the depth may decrease to zero towards the sidewall, depending on the shape of the shoulder area of the tire. Typically, a width of a groove is more than 3 mm, such as more than 4 mm. However, at or near a central area of the tread, a width of a groove may be less. In a central area of the tread, a width of a groove may be e.g. 1.5 mm or more.

[0130] Referring to FIG. 25, to further improve grip, the tread 110 may be provided with studs 250. Such studs 250 improve friction on icy roads. However, the tread 110 formed by the tread block arrangement 200 is also applicable as a tread of a studless tire. A studless tire may be a summer tire or a winter tire. The tread block arrangement 200 may limit an indicator 240 indicative of depth of the groove 120 (i.e. a wear indicator of the tire 100). The indicator 240 may also be indicative of the of the groove 120 having a depth that is sufficient or insufficient for driving on a snowy road.

[0131] The embodiments described herein that relate to a tire 100 refer to an unworn tire 100. It is understood that, in use, a tire 100 wears, which may affect the depth of its sipes and/or grooves. Such an unworn tire may comprise a pattern 260 (see FIG. 25) indicative of the tire being not used. The pattern 260 may be e.g. a portion of the tread 110 having fine protrusions and/or indentations that are indicative of the tire 100 unused, i.e. unworn.