Tire for big enduro type motorcycle

Abstract

The present invention relates mainly to a big enduro type motorcycle tire for off-road use. By virtue of a specific "cap and base" configuration of the tread band and of the specific mechanical properties of the compounds constituting it, the tire according to the invention improves the performance both on dry and wet surfaces, both in off-road and road driving.

Description

Technical Field

[0001] The present invention relates to a tire for a motorcycle, and more particularly, to a tire for a big enduro type motorcycle.

Background Art

[0002] Big enduro type or on / off-road motorcycles, also called big adventuring or dual-purpose, are motorcycles with high engine displacement, output, and mass designed to be ridden on both paved roads and off-road. These motorcycles generally have a cylinder volume of 1000 cm 3 or more, an output of 100 hp or more, a maximum torque of 100 Nm or more, and a mass of 180 kg or more.

[0003] Examples of big enduro type motorcycles are the BMW GS 1250R, Ducati Multistrada V4, KTM 1290 Super Adventure R, and Honda CRF1100L Africa Twin.

[0004] Motorcycles in this segment have a very wide range of uses, which range from pure road use corresponding to sports touring with a sports bike tendency to off-road use on so-called taped, unpaved tracks or routes including riverbeds, soft terrain, mud, sand, and unevenness of various types and difficulties, which is more severe than simply even roads.

[0005] To meet all these types of uses, there are various tire products on the market, each of which is weighted towards a clearly defined use, such as for sports driving on roads, for tourist driving on roads, for driving on a combination of unpaved roads, for on-road driving combined with easy off-road, or for severe off-road combined with on-road driving, etc.

[0006] Typically, tires for big enduro motorcycles, which are mainly intended for use on severe off-road combined with on-road riding, are marked with M+S and are approved to reach a maximum speed of 160 km / h (ETRTO speed index: Q), for example. These tires generally have a maximum radial section width of 90 - 170 mm (for example, 90 - 120 mm for front tires and 130 - 170 mm for rear tires) and are typically mounted on wheel rims with a seating diameter of approximately 17 inches (43.18 cm) to approximately 21 inches (53.34 cm) (for example, 19 inches (48.26 cm) - 21 inches (53.34 cm) for front tires and 17 inches (43.18 cm) - 18 inches (45.72 cm) for rear tires).

[0007] Tires mainly for road use are manufactured to maximize performance in terms of stability at high speeds, grip on dry and wet surfaces, handling on wet surfaces, fuel efficiency, traction, and braking, as well as comfort and wear regularity on asphalt road surfaces. In particular, these tires are often used under all-weather conditions throughout the year and must enable high reliability and performance on road surfaces with reduced grip, such as wet road surfaces.

[0008] Instead, tires for off-road use, even in harsh conditions, are made to maximize performance with respect to grip, traction, maneuverability, and directional stability on uneven, slippery, and / or inconsistent terrain (e.g., sand, mud, gravel) so as to effectively transmit even high driving and braking torques to the ground. These tires must also enable the aforementioned performance on wet surfaces.

[0009] Typically, in off-road use, the tire is used at an inflation pressure significantly lower than the inflation pressure during road use in order to increase the deflection of the tread from contact with the ground and, consequently, the footprint area, traction, and road grip of the motorcycle.

[0010] During road use, the pressure must then be suitably returned to the reference value typically indicated by the motorcycle manufacturer.

[0011] The handling of a motor vehicle perceived by the driver depends on an ideal compromise of inflation pressure that balances all variations of physical parameters induced by the pressure of the tire itself in the most beneficial way.

[0012] In practice, a decrease in pressure is accompanied by both a decrease in static stiffness (its components, lateral, vertical, and longitudinal), and thus the tire deforms more in all directions during operation, and a decrease in dynamic stiffness (drift and camber stiffness and self-aligning moment), and thus the tire's ability to generate dynamic forces in response to various stresses is lower. Such dynamic forces can become extremely strong on the road due to speed and higher camber angles.

[0013] Tires inflated at a pressure lower than the reference pressure are more deformed and inevitably operate at a higher heat regime. This can lead to premature tire wear as all components will degrade and lose their physical and mechanical characteristics once the exposure to thermal stress exceeds a certain level. Additionally, due to the greater compliance of the profile, the tire becomes more difficult to handle and slower to change direction.

[0014] Therefore, when transitioning from on-road to off-road driving and vice versa, it is advisable to adapt the tire pressure, even by significantly modifying it (e.g., by up to approximately 1.5 bar), in order to extend the tire's lifespan and maximize performance.

[0015] Typically, tires for big-enduro motorcycles are provided with a tread band having a tread pattern defined by a plurality of blocks separated by circumferential grooves and transverse grooves. Such blocks are arranged in both the central annular portion of the tread band and the annular shoulder portions on both sides of the tread band. Such tires generally have a solid / void ratio of from about 0.40 to about 0.65.

[0016] To optimize performance, it is typical in motorcycle tires to have a two-layer structure for the tread band.

[0017] Such a two-layer structure comprises a rolling layer or part (referred to as the cap) and a lower layer (referred to as the base) radially inside the rolling layer, constituting a so-called "cap and base" structure.

[0018] Typically in motorcycle tires, the cap layer and the base layer extend annularly and axially with the cap overlapping the base over the entire width of the tread band. As shown, for example, in EP3530487A1, the outermost cap in the radial direction forms the entire rolling surface, and the innermost base in the radial direction does not reach the rolling surface.

[0019] Thus, while it is possible to use an elastomeric material that can provide a cap having resistance to wear and resistance to crack formation, the elastomeric material of the base is particularly aimed at cooperating to reduce rolling resistance, properly supporting the cap, and / or being characterized by low hysteresis. The base may be disposed between the belt structure and the rolling layer.

[0020] However, in some alternative embodiments relating to motorcycle tires that are explicitly for road use (super sports sector), as shown in, for example, WO2019082012A1 and WO2021090152A1, the rolling surface of the tread band may comprise a central annular portion consisting of an underlying layer that appears on the surface, and the central annular portion is flanked on both sides by one or more annular sectors of different compounds. In this application, riding a motorcycle is completely different from the big enduro type characterized by a very high camber angle that keeps the shoulder portion of the tread in continuous contact with the road surface.

[0021] JP 2007-125988 discloses a cap and a base tire for a motorcycle in which a cap layer (32) extends axially over the entire width of the central annular portion (W2), and a base layer (34) extends axially over the entire width of the central annular portion (W2) and to each annular portion of the shoulder (W1).

[0022] The document also does not report the presence of blocks in the tread having a specific void / solid ratio, nor the extension of the annular portions. The elastic modulus values E1 and E2 of the compounds of the cap layer (32) and the base layer (34) measured at 60°C without further indication of the test conditions are assumed to be 11 kgf / mm 2 ≦E1≦16 kgf / mm 2 and 7 kgf / mm 2 ≦E2≦13 kgf / mm 2 respectively (paragraph 0019).

[0023] Japanese Patent No. 6053550 discloses a cap and a base tire for a two-wheeled vehicle including a base layer (38), an intermediate layer (40), and a cover layer (42) laminated in the radial direction. The document does not describe the elastic modulus values of the compounds making up those layers.

Summary of the Invention

Problems to be Solved by the Invention

[0024] The applicant has found, by examining the motorcycle segment, that "big enduro" type motorcycles have a very wide range of uses, as already described.

[0025] In order to optimally cover the entire usage area, the applicant has noticed that big enduro type motorcycles should be equipped with tires suitable for enabling high performance both on roads (mainly stability at high speeds, grip in dry and wet conditions, handling) and off-road (mainly traction, maneuverability, and directional stability), in accordance with the ability to travel long kilometers.

[0026] However, the applicant has found that the aforementioned performance characteristics are at least partially contradictory to each other due to the increasingly widespread current trend of emphasizing road performance on the one hand and off-road performance on the other hand. In fact, tires that enable high performance on roads usually have performance limits under severe off-road conditions, and vice versa.

[0027] The applicant has also noted that tires that combine on-road and off-road uses with a good compromise solution do not make it possible to achieve the highest satisfactory performance in either of the two fields (roads and off-road). In this regard, these days, the market has shifted to more specialized solutions according to customer requirements, assuming several segments of tires for big enduro type motorcycles, and it should be noted that each of these segments places emphasis on specific widespread uses of motorcycles.

[0028] Consistently, the applicant has proposed tires for big enduro motorcycles suitable mainly for use on roads and tires for big enduro motorcycles suitable mainly for off-road use.

[0029] The applicant has focused on the segment of tires designed for the widespread off-road use of big enduro motorcycles.

[0030] These tires are generally selected by users who seek performance on off-road routes and assume that road use is limited to the travel segments to / from off-road routes.

[0031] Although road use of this type of tire is permitted, it is mainly intended for off-road use, and even more severe off-road use. In this specific application, unlike when mainly used on roads, the motorcycle is operated in a substantially vertical position or in a state where the roll angle (camber) is limited to about 25° to 30°, and the shoulder portion of the tread band of the tire hardly contacts the ground.

[0032] The applicant has conceived of making a tire that can maintain excellent off-road performance and has on-road behavior suitable for allowing the user to take a longer and clearer road journey safely and comfortably compared to simple travel to / from off-road routes, and that improves on-road behavior on dry road surfaces where grip is of particular importance and, above all, on wet road surfaces.

[0033] The applicant has found that, in order to improve the above-mentioned on-road behavior while maintaining off-road behavior, contrary to the above typical configuration, at least one cap and a tread band formed by a base are provided, where the surface of the lower layer, i.e., the base, is on the radially outer portion of the tread band in the lateral annular portion (shoulder portion) of the tread band, while the central annular portion on the radially outer side is formed by a cap layer.

[0034] This arrangement of the layers, combined with the selection of a suitable elastomeric compound having suitable properties for the composition of the cap layer and the base layer, first means that during off-road use, even when the inflation pressure is maximum, the tread band of the tire bends more at the shoulder portion, resulting in a larger footprint area, and thus better traction, handling, and comfort.

[0035] This greater flexibility at the shoulder portion and the resulting larger footprint area of the tread band provide an advantage in off-road performance regardless of the pressure used, and in fact enable excellent off-road driving performance even when the pressure is only equal to or slightly less than the pressure on the road.

[0036] Furthermore, this tire has unexpectedly better road performance in terms of stability, handling, and comfort on both dry and wet road surfaces.

[0037] This result is completely innovative and contrary to the general knowledge of the specific sector of big enduro tires mainly used off-road.

[0038] The applicant has found that by using this cap and base configuration and by making selections for the realization of a compound having suitable properties for the precisely required performance in use at specific positions of the tread band where the compound is present, it is possible to improve on-road performance while maintaining or even improving off-road performance even when the inflation pressure is maximum or the shrinkage is minimum.

[0039] The applicant has actually intuitively realized that in big enduro tires mainly used off-road, the tread band is typically subject to different stress and heat regimes during operation. The different stress and heat regimes are - maximum for the central annular portion that is constantly in contact with the road and off-road surfaces, - Most of this sector does not touch the ground in straight riding, but is intermediate with respect to the shoulder portion, which is a target of continuous curvature especially in off-road, - It is minimal with respect to the inner lower layer that does not touch the road surface and is not a target of such prominent and repeated curvature.

[0040] Therefore, the applicant recognizes that by using this innovative cap and base configuration, it is possible to meet the extremely high performance requirements of the central annular portion with a specific first cap compound having certain optimal properties (higher wear resistance, better adhesion), and to comply with the different requirements of the shoulder portion (flexibility) and the inner lower layer (temperature stability) with a second base compound having different properties from the first compound. The second compound forms the lower layer and appropriately occurs only on the surface in the shoulder portion.

Means for Solving the Problems

[0041] Therefore, the present invention relates to a tire (1) for an in- / off-road motorcycle (big enduro). The tire (1) for an in- / off-road motorcycle (big enduro) includes a tread band (8) having a total radial thickness S, and includes a plurality of blocks and grooves defining a void / solid ratio of 0.40 to 0.65 in the tread band (8). The tread band (8) includes a central annular portion (A) symmetrically arranged across the equatorial plane (X-X), and a pair of annular shoulder portions (B) symmetrically arranged on both sides with respect to the central annular portion (A) and adjacent to the central annular portion (A). - The central annular portion (A) extends axially over a width of 70% to 90% of the width of the tread band, and includes a rolling layer (8a) having a radial thickness S1 at the outermost radial position, and a lower layer (8b) having a radial thickness S2, which is adjacent to the rolling layer (8a) and is arranged at the innermost radial position. The tread band (8) has a total radial thickness S = S1 + S2. The rolling layer (8a) extends axially over the entire width of the central annular portion (A), and the lower layer (8b) extends axially over the entire width of the central annular portion (A) and over the entire width of each annular shoulder portion (B). - Each annular shoulder portion (B) extends axially over a width of 5% to 15% of the width of the tread band, and the entire total radial thickness S of the tread band is made from the lower layer (8b). The rolling layer (8a) contains a first elastomeric compound characterized by a modulus of elasticity E’ (E’ modulus) measured at 70 °C and 10 Hz according to the method described in the experimental part, of 5.00 to 6.50 MPa, and the lower layer (8b) contains a second elastomeric compound characterized by a modulus of elasticity E’ (at 70 °C and 10 Hz) of 3.50 to 4.60 MPa, and the percentage ratio between the coefficient E’ of the second compound and the coefficient E’ of the first compound is 70% to 90%.

[0042] Definitions The term "motorcycle tire" means a vulcanized tire having a large curvature ratio (typically greater than 0.20) and capable of reaching a large camber angle during cornering.

[0043] The "curvature ratio" means the ratio between the distance between the radially highest point of the tread band and the maximum radial cross-sectional width of the tire (this distance is also identified as the "deflection") and the said maximum width of the tire in the tire cross-section.

[0044] The "camber angle" means the angle between the equatorial plane of the tire mounted on a motorcycle wheel and the plane perpendicular to the road surface.

[0045] The "maximum radial cross-sectional width" or "maximum chord" means the maximum width of the tire profile, i.e., the dimension of the line segment having as endpoints the two axially outermost points of the tread band profile.

[0046] The "equatorial plane" of a tire means a plane that is perpendicular to the axis of rotation of the tire and divides the tire into two symmetrically equal parts.

[0047] The "tread pattern" means that which is represented by all the points of the tread band (including grooves) in a plane that is perpendicular to the equatorial plane of the tire and touches the maximum diameter of the tire. The tread pattern is defined by a plurality of blocks that are separated by grooves and may include recesses in some cases.

[0048] A "block" means a part of the tread band separated by grooves. When a block is positioned at the outermost axial part of the tread band, the block is axially delimited by the outermost axial surface of the tread band and, at the innermost axial position, is axially delimited by at least one groove.

[0049] A "groove" means a groove formed in the tread band to delimit a part of a block.

[0050] Angles, and / or linear quantities (such as distance, width, length, amplitude, axial cross-section, and / or circumferential cross-section, etc.), and / or surface measurements should be understood as referring to the tread pattern defined above.

[0051] "Width" means a dimension measured along a direction perpendicular to the equatorial plane.

[0052] "Circumferential length" means a dimension measured along a direction on the equatorial plane or a direction parallel to the equatorial plane.

[0053] The expression "maximum extension" for a block indicates the distance between the two outermost points of the block measured along a direction perpendicular to the equatorial plane, or along a direction parallel to the equatorial plane or a direction on the equatorial plane, in the axial or circumferential direction.

[0054] The terms "radial direction" and "axial direction", as well as the expressions "radially inner / outer" and "axially inner / outer", are used to refer to the direction parallel to the equatorial plane of the tire and the direction perpendicular to the equatorial plane of the tire, respectively, that is, the direction perpendicular to the axis of rotation of the tire and the direction parallel to the axis of rotation of the tire, respectively.

[0055] The terms "circumferential direction" and "circumferentially" are used to refer to the direction of circumferential development of the tire, that is, the rolling direction of the tire, and that direction corresponds to the direction on a plane that coincides with or is parallel to the equatorial plane of the tire.

[0056] The "circumferential development" of a tire or a tread band or a part of a tread band means the plan view development of the radially outermost surface of the tire or the tread band or the part of the tread band on a plane tangential to the tire.

[0057] The expressions "most axially inner" and "most axially outer" indicate positions closer to and farther from the equatorial plane with respect to the reference element, respectively.

[0058] The annular part of the tread band means a part of the tread band that extends circumferentially over the entire tread band and has a predetermined axial extension.

[0059] The distance of the annular tread part from the equatorial plane is estimated axially by referring to the closest end face parallel to the equatorial plane of the annular part.

[0060] "Substantially axial" means a direction inclined at an angle between 70° and 90° with respect to the equatorial plane of the tire.

[0061] "Substantially circumferential" means a direction oriented at an angle between 0° and 20° with respect to the equatorial plane of the tire.

[0062] The "circumferential groove" means a groove having at least one groove portion extending along a substantial circumferential direction.

[0063] The "transverse groove" means a groove having at least one groove portion extending along a substantial axial direction.

[0064] The expression "substantially parallel" indicates not only a state of perfect parallelism but also a state in which something deviates from perfect parallelism by an angle of 10° or less.

[0065] The "solid / void ratio" means the ratio between the total surface of the grooves of a given annular portion of the tire tread pattern (in some cases the entire tread band or the tread pattern) and the surface of a given tread pattern portion (in some cases the entire tread band or the tread pattern).

[0066] The "footprint area" of a tire means the portion of the tire that contacts the ground or road surface when the tire is mounted on a wheel rim and a predetermined vertical load is applied to the tire.

[0067] The term "phr" (acronym for parts per hundreds of rubber, parts per 100 parts of rubber weight) indicates the parts by weight of a given elastomer compound component per 100 parts by weight of the elastomer polymer, taking into account the net amount of any plasticizer extender oil.

[0068] "Elastomeric material" means a material containing a vulcanizable natural or synthetic polymer and a reinforcing filler, and (according to the definition of ASTM D1566-11 Standard Terminology Relating To Rubber) such a material after vulcanization at room temperature is easily deformed by force and can quickly and vigorously recover its substantial original shape and dimensions after the deforming force is removed.

[0069] The term "diene polymer" refers to a polymer or copolymer derived from the polymerization of one or more different monomers, at least one of which is a conjugated diene (conjugated diolefin).

[0070] The term "elastomer compound" refers to a compound obtainable by mixing at least one elastomeric polymer with at least one of the additives customarily used in the preparation of tire compounds and optionally heating.

[0071] The term "vulcanizable elastomer compound" refers to an elastomer compound in a vulcanizable state obtainable by incorporating all additives including additives for vulcanization into the elastomer compound.

[0072] The term "vulcanized elastomer compound" means a material obtainable by vulcanizing a vulcanizable elastomer compound.

[0073] The term "vulcanization" typically means the crosslinking reaction of natural or synthetic rubber induced by a sulfur-based crosslinking agent.

[0074] The term "vulcanizing agent" refers to a product capable of converting natural or synthetic rubber into an elastic and resistant material due to the formation of a three-dimensional network of intermolecular and intramolecular bonds. Typical vulcanizing agents are sulfur-based compounds such as elemental sulfur, polymeric sulfur, and sulfur donors such as bis[(trialkoxysilyl)propyl] polysulfide, thiuram, dithiomorpholine, and caprolactam-disulfide.

[0075] The term "vulcanization accelerator" means a compound capable of reducing the period and / or operating temperature of the vulcanization process, such as TBBS, common sulfenamides, thiazoles, dithiophosphates, dithiocarbamates, guanidines, and sulfur donors such as thiuram.

[0076] The term "vulcanization activator" refers to a product that can further accelerate vulcanization and cause vulcanization in a shorter time and, in some cases, at a lower temperature. An example of an activator is the stearic acid-zinc oxide system.

[0077] The term "vulcanization retarder" refers to a product that can delay the start of the vulcanization reaction and / or suppress undesired secondary reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0078] The term "vulcanization package" is meant to refer to a vulcanizing agent and one or more vulcanization additives selected from among vulcanization activators, accelerators, and retarders.

[0079] The term "reinforcing filler" refers to a reinforcing material preferably selected from among carbon black, conventional silica such as silica from sand precipitated with strong acid, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicate, kaolin, silicate fiber, and mixtures thereof, and typically used in sectors to improve the mechanical properties of tire rubber.

[0080] The term "white filler" refers to a conventional reinforcing material used in sectors, preferably selected from among conventional silica and silicates such as sepiolite, palygorskite (also known as attapulgite), montmorillonite, and allophane, which may be modified and / or derivatized by acid treatment in some cases. Typically, white fillers have surface hydroxyl groups.

[0081] The expression "reinforcing cord", or more simply "cord", means a filamentary element consisting of one or more elongated elements (also called "yarns") that are covered by or incorporated into the matrix of an elastomeric material in some cases.

Brief Description of the Drawings

[0082]

Figure 1

Figure 2

DETAILED DESCRIPTION OF THE INVENTION

[0083] In the following of this specification and in the appended claims, even if not explicitly shown, any numerical value is understood to be modified by the term "about" for the purpose of further indicating any value that slightly deviates from the stated numerical value, for example, taking into account the typical dimensional tolerances of the reference sectors.

[0084] Furthermore, when reference is made to any range of values between a minimum value and a maximum value, the minimum value and the maximum value are understood to be included within the range unless otherwise explicitly defined.

[0085] Furthermore, even if not specifically described explicitly, all ranges include any combination of the stated maximum and minimum values and any intermediate ranges.

[0086] The tire according to the invention is characterized by one or more of the following features used individually or in combination.

[0087] The tire according to the invention comprises a tread band (8) with a total radial thickness S.

[0088] The total radial thickness S of the tread band (8), as well as the radial thicknesses S1 and S2 of the tread layer (8a) and the bottom layer (8b), relate to the tire after molding and vulcanization.

[0089] To enable appropriate tread life and tire integrity, preferably, the total radial thickness S of the tread band is 10 mm to 20 mm, more preferably 12 mm to 16 mm, for example 14.5 mm. Further, the thickness of the tread band must be sufficient to ensure that the grooves do not come too close to the carcass ply and / or belt structure after vulcanization.

[0090] The total radial thickness S of the tread band does not have to be constant. Specifically, it may vary from the central annular portion to the shoulder portion.

[0091] In one embodiment, the total radial thickness S is greater in the central annular portion (A) than in the annular shoulder portion (B). Preferably, the total radial thickness S of the central annular portion (A) is 110% to 120% of the total radial thickness S of the annular shoulder portion B.

[0092] Preferably, the thickness S1 of the tread layer (8a) in the central annular portion (A) is between 9 mm and 17 mm, more preferably between 11 mm and 15 mm.

[0093] The thickness S2 of the lower layer (8b) in the central annular portion (A) is not uniform as a whole because it is subject to lateral movement (sliding) during vulcanization and in particular during the molding process, as well as deformation caused by molding to define blocks and grooves.

[0094] Preferably, the thickness S2 of the lower layer (8b) in the central annular portion (A) is 0.8 mm to 4 mm, more preferably 1.0 mm to 3 mm, and even more preferably 1.0 mm to 2.0 mm, so as to provide appropriate support.

[0095] In the annular shoulder portion (B), the thickness S2 of the lower layer (8b) instead coincides with the total radial thickness S of the tread band.

[0096] In the tire of the present invention, the sum of the widths of the axial developments of the two shoulder sectors (B) and the width of the axial development of the central annular sector (A) corresponds to the width of the axial development of the tread band (8).

[0097] Preferably, the central annular portion (A) extends axially over a width of 75% to 85% of the width of the tread band.

[0098] Preferably, each annular shoulder portion (B) extends axially over a width of 7.5% to 12.5% of the width of the tread band.

[0099] Preferably, the axial developments of the two annular shoulder sectors (B) have the same width.

[0100] In the tire of the present invention, the rolling layer (8a) is preferably entirely formed of the first elastomer compound, and / or the lower layer (8b) is entirely formed of the second elastomer compound.

[0101] In the tire of the present invention, the first compound of the rolling layer of the central annular portion (A) has a dynamic elastic modulus E' (measured at 70°C and 10 Hz according to the method described in the experimental part) greater than the elastic modulus E' (70°C, 10 Hz) of the second compound of the annular shoulder portion (B) during compression.

[0102] Preferably, the first compound and the second compound are selected such that the finished (vulcanized) tire has a vulcanized elastomer material having a dynamic elastic modulus E' (measured at 70°C and 10 Hz) of 75% to 90%, more preferably 80% to 85% of the dynamic elastic modulus E' (measured at 70°C and 10 Hz) of the vulcanized elastomer material of the rolling surface of the central annular portion (A) in the annular shoulder portion (B).

[0103] Preferably, the first elastomer compound is characterized by an elastic modulus E' of 6.50 MPa or less, more preferably 6.00 MPa or less (measured at 70°C and 10 Hz).

[0104] Preferably, the first elastomer compound is characterized by an elastic modulus E' of 5.00 to 6.00 MPa, more preferably 5.00 to 5.50 MPa (measured at 70°C and 10 Hz).

[0105] Preferably, the first elastomer compound is characterized by an elastic modulus E' of more than 5.00 MPa, more preferably more than 5.50 MPa (measured at 70°C and 10 Hz).

[0106] Preferably, the second elastomer compound is characterized by an elastic modulus E' of 4.60 MPa or less, more preferably 4.50 MPa or less, even more preferably 4.40 MPa or less (measured at 70°C and 10 Hz).

[0107] Preferably, the second elastomer compound is characterized by an elastic modulus E' of more than 4.00 MPa, more preferably more than 4.20 MPa (measured at 70°C and 10 Hz).

[0108] Preferably, the second elastomer compound is characterized by an elastic modulus E' of 4.00 to 4.50 MPa, more preferably 4.20 to 4.40 MPa (measured at 70°C and 10 Hz).

[0109] In one embodiment, the first elastomer compound is characterized by an elastic modulus E' of more than 5.00 MPa, more preferably more than 5.50 MPa (measured at 70°C and 10 Hz), and the second elastomer compound is characterized by an elastic modulus E' of 4.60 MPa or less, more preferably 4.50 MPa or less, even more preferably 4.40 MPa or less (measured at 70°C and 10 Hz).

[0110] Preferably, the difference between the elastic modulus E' of the first compound (measured at 70°C and 10 Hz) and the elastic modulus E' of the second compound is 0.3 to 2.3 MPa, more preferably 0.4 to 1.5 MPa, and even more preferably 0.6 to 1.1 MPa.

[0111] In the tire of the present invention, the first compound of the rolling layer of the central annular portion (A) and the second compound of the lower layer of the tread band (8) are such that the completed (vulcanized) tire has a loss tangent (tan delta) (measured at 70°C and 10 Hz) greater than that of the vulcanized elastomer material of the annular shoulder portion (B) on the rolling surface of the central annular portion (A).

[0112] Preferably, the first compound and the second compound are selected such that the completed (vulcanized) tire has a loss tangent (tan delta) (measured at 70°C and 10 Hz) of 45% to 65%, more preferably 50% to 60%, of the loss tangent of the vulcanized elastomer material of the rolling surface of the central annular portion (A) in the annular shoulder portion (B).

[0113] Preferably, the first elastomer compound is characterized by a loss tangent (measured at 70°C and 10 Hz) greater than 0.220, more preferably greater than 0.230.

[0114] Preferably, the first elastomer compound is characterized by a loss tangent (measured at 70°C and 10 Hz) of 0.220 to 0.280, more preferably 0.230 to 0.270.

[0115] Preferably, the second elastomer compound is characterized by a loss tangent (measured at 70°C and 10 Hz) of 0.180 or less, more preferably 0.170 or less.

[0116] Preferably, the second elastomer compound is characterized by a loss tangent of 0.120 to 0.180, more preferably 0.135 to 0.150 (measured at 70 °C and 10 Hz).

[0117] Preferably, the first elastomer compound is characterized by an IRHD hardness measured at 23 °C of less than 78, more preferably less than 75, and / or greater than 66, more preferably greater than 68.

[0118] Preferably, the first elastomer compound is characterized by an IRHD hardness measured at 23 °C of 66 to 76, more preferably 68 to 74.

[0119] Preferably, the second elastomer compound is characterized by an IRHD hardness measured at 23 °C of less than 73, more preferably less than 71, and / or greater than 63, more preferably greater than 65.

[0120] Preferably, the second elastomer compound is characterized by an IRHD hardness measured at 23 °C of 63 to 73, more preferably 65 to 71.

[0121] In this tire, the first compound preferably has a load CA3 at 300% elongation that is lower than the load CA3 of the second compound (measured at 23 °C according to the UNI6065:2001 standard).

[0122] Preferably, the first elastomer compound is characterized by a load CA1 at 100% elongation of 1.7 to 2.3 MPa, more preferably 1.9 to 2.1 MPa, and / or a load CA3 at 300% elongation of 7.7 to 10.5 MPa, more preferably 8.6 to 9.5 MPa, measured at 23 °C according to the UNI6065:2001 standard.

[0123] Preferably, the second elastomer compound is characterized by a load CA1 at 100% elongation of 1.7 to 2.3 MPa, more preferably 1.9 to 2.1 MPa, measured at 23°C according to the UNI6065:2001 standard, and / or a load CA3 at 300% elongation of 8.6 to 11.7 MPa, more preferably 9.7 to 10.7 MPa.

[0124] In a preferred embodiment of the tire of the present invention, the first compound of the tread layer in the central annular portion (A) of the tread band (8) has a load value CA3 of 7.7 to 10.5 MPa measured at 23°C, a dynamic elastic modulus E of 5.00 to 6.00 MPa measured at 70°C and 10 Hz, a loss tangent of 0.220 to 0.280 measured at 70°C and 10 Hz, a dynamic elastic modulus E' of 6.60 to 10.00 MPa measured at 23°C and 10 Hz, and a loss tangent of 0.320 to 0.431 measured at 23°C and 10 Hz.

[0125] More preferably, the first compound has a load value CA3 of 8.6 to 9.5 MPa measured at 23°C, a dynamic elastic modulus E' of 5.00 to 5.50 MPa measured at 70°C and 10 Hz, a loss tangent between 0.230 and 0.270 measured at 70°C and 10 Hz, a dynamic elastic modulus E' of 7.00 to 8.60 MPa measured at 23°C and 10 Hz, and a loss tangent of 0.337 to 0.412 measured at 23°C and 10 Hz.

[0126] In a preferred embodiment of the present invention, the second compound of the lower layer has a load value CA3 of 8.6 to 11.7 MPa measured at 23°C, a loss tangent of 0.120 to 0.180 measured at 70°C and 10 Hz, a dynamic elastic modulus E' of 4.00 to 4.50 MPa measured at 70°C and 10 Hz, a dynamic elastic modulus E' of 4.80 to 6.50 MPa measured at 23°C and 10 Hz, and a loss tangent of 0.262 to 0.354 measured at 23°C and 10 Hz.

[0127] More preferably, the second compound has a load value CA3 of 9.7 to 10.7 MPa measured at 23°C, a loss tangent of 0.135 to 0.150 measured at 70°C and 10 Hz, a dynamic elastic modulus E' of 4.20 to 4.40 MPa measured at 70°C and 10 Hz, a dynamic elastic modulus E' of 5.10 to 6.30 MPa measured at 23°C and 10 Hz, and a loss tangent of 0.277 to 0.339 measured at 23°C and 10 Hz.

[0128] In this preferred embodiment, the first compound has an IRHD hardness of 69 to 73 at 23°C, while the second compound has an IRHD hardness of 65 to 69.

[0129] Typically, for the preparation of the compounds of the tire according to the present invention, the raw materials listed below, and other raw materials typically used in the tire industry sector can be used.

[0130] Specifically, for the preparation of the compound of the lower layer (8b) and the compound of the tread layer (8a), for example, a sulfur-crosslinkable elastomer composition (vulcanized), a peroxide, or other systems known to those skilled in the art are commonly used, and an elastomer composition containing at least one elastomer diene polymer selected from elastomer diene polymers particularly suitable for the production of tires, or an elastomer polymer or copolymer with an unsaturated chain having a glass transition temperature (Tg) usually below 20°C, preferably in the range of -110°C to 0°C can be used.

[0131] The compounds of the lower layer (8b) and the compounds of the rolling layer (8a) preferably contain 100 phr of at least one diene elastomer polymer, which is preferably at least one styrene-butadiene rubber selected from solution-polymerized styrene-butadiene rubber (S-SBR), emulsion-polymerized styrene-butadiene rubber (E-SBR), or a combination thereof. The styrene-butadiene rubber may be present in an amount in the range of, for example, 20 to 90 phr.

[0132] Commercial examples of SBR polymers useful in the present invention are Asahi Kasei (registered trademark) (Japan)'s Toughlene E581 and E680 polymers, Trinseo (Germany)'s SPRINTAN SLR4602, SLR3402, and SLR4630, JSR Corporation (Japan)'s HPR620, Arlanxeo (Germany)'s BUNA SL-4518, BUNA SE1502, and BUNA CB22, ENI (Italy)'s Europrene5543T, Europrene1739, and Intol1789, Japan Synthetic Rubber Co., Ltd. (Japan)'s HP755, and Zeon Corporation (Japan)'s NIPOL NS522.

[0133] The compounds of the lower layer (8b) and the compounds of the rolling layer (8a) may contain, for example, 10 to 50 phr of at least one butadiene polymer (BR), preferably low-cis functionalized BR.

[0134] The compounds of the lower layer (8b) and the compounds of the rolling layer (8a) are selected from alkylene-based, preferably optionally hydroxy- or epoxy-functionalized, liquid polymers and copolymers based on butadiene (BR), isoprene (IR), isoprene / butadiene rubber (IBR), styrene / butadiene rubber (SBR), or depolymerized liquid natural rubber (NR), and may contain one or more liquid polymers in an amount of, for example, 1 to 40 phr.

[0135] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one resin.

[0136] The at least one resin may be a polyterpene resin selected from homopolymers or copolymers of α-pinene, β-pinene, limonene, and vinyl aromatic monomers (styrene) and / or aromatic monomers (phenol).

[0137] Examples of commercial terpene-based natural resins are Piccolyte F90 and Piccolyte F105 resins 2495 manufactured by PINOVA, and Dercolyte A115 and Dercolyte M115 manufactured by DRT.

[0138] The at least one resin may be a hydrocarbon resin selected from, for example, resins derived from coumarone-indene resins, resins derived from styrene-indene resins, resins derived from styrene-alkylstyrene resins, and resins derived from aliphatic resins.

[0139] A specific example of a commercially available hydrocarbon resin is NOVARES C resin (indene-coumarone synthetic resin) manufactured by RUTGERS CHEMICAL GmbH.

[0140] Examples of commercially available styrene-indene hydrocarbon resins are UNILENE A100 manufactured by Braskem, and Novares TT90 manufactured by Ruetgers.

[0141] The at least one resin may be present, for example, in an amount of 0 to 50 phr.

[0142] The compound of the lower layer (8b) and the compound of the rolling layer (8a) according to the present invention may contain at least one plasticized oil.

[0143] The term "plasticized oil" means a process oil derived from process oils derived from petroleum, process oils derived from mineral oils, process oils derived from vegetable oils, process oils derived from synthetic oils, or a combination thereof.

[0144] The plasticized oil may be a process oil derived from petroleum, selected from paraffin (saturated hydrocarbons), naphthenes, polycyclic aromatics, and mixtures thereof.

[0145] Examples of suitable process oils derived from petroleum are aromatic oils, paraffinic oils, naphthenic oils such as Mild Extract Solvated (MES), Distillate Aromatic Extract (DAE), Treated Distillate Aromatic Extract (TDAE), Treated Residual Aromatic Extract (TRAE), Residual Aromatic Extract (RAE), etc., known in the industry.

[0146] The plasticized oil may be a natural or synthetically derived oil derived from the esterification of glycerol with fatty acids, including glycerol tristearate, diglyceride, monoglyceride, or mixtures thereof.

[0147] Examples of suitable vegetable oils are sunflower oil, soybean oil, linseed oil, rapeseed oil, castor oil, and cottonseed oil.

[0148] The plasticized oil may be a synthetic oil selected from alkyl esters or aryl esters of phthalic acid or phosphoric acid.

[0149] An example of an oil used in the compound is Lanxess' tri-(2-ethylhexyl)-phosphate (TOF).

[0150] Preferably, the oil derived from natural (e.g., plant) or synthetic sources has a glass transition temperature (Tg) of less than -70 °C (in accordance with the ISO 28343:2010 standard).

[0151] Examples of suitable commercial plasticized oils are NYTEX 4700 sold by Nynas, which is an oil derived from petroleum, EXTENSOIL 1471 sold by Repsol, VIVATEC 500 sold by H&R, and RADIA 6132 sold by Oleon, Agripure AP18 and Agripure AP75 sold by Cargill, which are vegetable oils.

[0152] The total amount of oil, including both the added oil and optionally the oil already present as a diluent for the elastomeric polymer, may be, for example, 10 to 70 phr.

[0153] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one reinforcing filler in an amount of, for example, 10 phr to 150 phr.

[0154] The reinforcing filler may be selected from carbon black, white fillers, silicate fibers, or mixtures thereof.

[0155] In one embodiment, the reinforcing filler is a white filler selected from hydroxides, oxides and hydrated oxides, salts and hydrated salts of metals, silicate fibers, or mixtures thereof. Preferably, the white filler is silica.

[0156] Suitable commercial examples of conventional silica are Zeosil 1165MP from Solvay and Ultrasil 7000GR from Evonik.

[0157] In one embodiment, the reinforcing filler is carbon black.

[0158] Preferably, the carbon black is 20 m 2 / g or more, preferably more than 50 m 2 / g, and is selected from carbon blacks having a surface area.

[0159] The carbon black may be, for example, N234, N326, N330, N375, or N550, N660 sold by Birla Group (India), or CRX1391 by Cabot Corporation.

[0160] The reinforcing filler may include a mixture, for example, a mixture of carbon black and silica.

[0161] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one vulcanizing agent in an amount of, for example, 0.5 to 7 phr.

[0162] The at least one vulcanizing agent is preferably selected from sulfur or, alternatively, sulfur-containing molecules (sulfur donors) such as bis[(trialkoxysilyl)propyl] polysulfide and mixtures thereof.

[0163] Preferably, the vulcanizing agent is sulfur, preferably selected from soluble sulfur (crystalline sulfur), insoluble sulfur (polymer sulfur), (iii) oil-dispersed sulfur, and mixtures thereof.

[0164] Commercial examples of vulcanizing agents suitable for use in the elastomer composition of the present invention are Rhenocure® IS90P from RheinChemie or sulphur Redball Superfine from International Sulfur Inc.

[0165] In this elastomer compound, the vulcanizing agent may be used together with adjuvants such as vulcanization activators, accelerators, and / or retarders known to those skilled in the art.

[0166] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one vulcanization activator.

[0167] Vulcanization activators suitable for use in this elastomer compound are zinc compounds, specifically ZnO, ZnCO3, zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms, and the zinc salts are preferably formed in situ in the elastomer compound by reaction of ZnO with fatty acids or mixtures thereof. For example, zinc stearate preferably formed in situ by ZnO and fatty acids, or magnesium stearate formed by MgO, or mixtures thereof may be used.

[0168] The vulcanization activator may be present in the elastomer compound of the present invention in an amount of, for example, 0.2 phr to 15 phr.

[0169] Preferred activators result from the reaction of zinc oxide and stearic acid.

[0170] Examples of activators are Aktiplast ST from Rheinchemie and zinc bis-neodecanoate VALIKAT Zn1910 from Umicore.

[0171] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one vulcanization accelerator.

[0172] Conventionally used primary vulcanization accelerators and secondary vulcanization accelerators may be selected from, for example, dithiocarbamates, guanidines, thioureas, thiazoles, sulfenamides, sulfenimides, thiurams, amines, xanthates, or mixtures thereof.

[0173] Preferably, the accelerator is selected from mercaptobenzothiazole (MBT), N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), dibenzothiazole disulfide (MBTS), and mixtures thereof.

[0174] Commercial examples of accelerators suitable for use in this elastomer compound are N-cyclohexyl-2-benzothiazyl-sulfenamide Vulkacit® (CBS or CZ) and N-tert-butyl 2-benzothiazylsulfenamide Vulkacit® NZ / EGC sold by Lanxess, tetrabenzylthiuram disulfide (Perkacit® TBzTD) of Huatai Chemicals, dibenzothiazole disulfide Rhenogran MBTS80, and N-tert-butyl-2-benzothiazylsulfenamide TBBS.

[0175] The vulcanization accelerator may be employed, for example, in an amount of 0.05 phr to 10 phr.

[0176] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one vulcanization retarder.

[0177] The vulcanization retarder may be selected from urea, phthalic anhydride, N-nitrosodiphenylamine, N-cyclohexylthiophthalimide (CTP or PVI), and mixtures thereof.

[0178] A commercial example of a suitable retarder is N-cyclohexylthiophthalimide VULKALENT G from Lanxess.

[0179] The vulcanization retarder may be present, for example, in an amount of 0.05 phr to 2 phr.

[0180] The compounds of the lower layer (8b) and the compounds of the rolling layer (8a) may contain at least one silane coupling agent in an amount of, for example, 0.5 to 10.0 phr.

[0181] Preferably, the coupling agent is a drug selected from drugs having at least one hydrolyzable silane group, and the drug is, for example, the following general formula (III): (R’)3Si-C n H 2n -X (III) It may be identified by the above formula, in which the R’ groups, which are equal to or different from each other, are selected from an alkyl group, an alkoxy group, or an aryloxy group, or from a halogen atom on condition that at least one of the R’ groups is an alkoxy group or an aryloxy group, n is an integer from 1 to 6, and X is nitrose, mercapto, amino, epoxide, vinyl, imide, chloro, -(S) m C n H 2n -Si-(R’)3, and a group selected from -S-COR’, where m and n are integers from 1 to 6, and the R’ group is as defined above.

[0182] Preferred silane coupling agents are bis(3-triethoxysilylpropyl)tetrasulfide and bis(3-triethoxysilylpropyl)disulfide. The coupling agent may be added by itself or mixed with an inert filler (such as carbon black) to facilitate incorporation into the elastomer compound.

[0183] An example of a silane coupling agent is TESPT bis(3-triethoxysilylpropyl)tetrasulfide Si69 sold by Evonik.

[0184] The compounds of the lower layer (8b) and the compounds of the rolling layer (8a) may contain additional raw materials commonly used in the sector, such as antioxidants and / or anti-ozonants (anti-ageing agents), waxes, adhesives, etc.

[0185] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one wax, such as a mixture of petroleum wax or paraffin, in an amount of, for example, 0.1 phr to 20 phr.

[0186] Commercial examples of suitable waxes are Repsol's N-paraffin mixture and Rhein Chemie's Antilux® 654 microcrystalline wax.

[0187] The compound of the lower layer (8b) and the compound of the rolling layer (8a) may contain at least one antioxidant in a total amount of, for example, 0.1 phr to 20 phr.

[0188] The antioxidant may be selected from N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N-(1,3-dimethyl-butyl)-n'-phenyl-p-phenylenediamine (6PPD), N,N'-bis-(1,4-dimethyl-pentyl)-p-phenylenediamine (77PD), N,N'-bis-(1-ethyl-3-methyl-pentyl)-p-phenylenediamine (DOPD), N,N'-bis-(1,4-dimethyl-pentyl)-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N,N'-di-β-naphthyl-p-phenylenediamine (DNPD), N,N'-bis(1-methylheptyl)-p-phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine (44PD), N-phenyl-N-cyclohexyl-p-phenylenediamine, N-phenyl-N'-1-methylheptyl-p-phenylenediamine, etc., and mixtures thereof.

[0189] A commercial example of a suitable antioxidant is 6PPD from Solutia / Eastman.

[0190] In a preferred embodiment, the first elastomer compound is obtained by vulcanizing an elastomer composition, which contains 0 to 30 phr of at least one liquid polymer, 0 to 20 phr of at least one resin, and 10 to 60 phr of at least one plasticizing oil, and if present, the total of the liquid polymer and resin and the plasticizing oil is 20 to 90 phr, the elastomer composition contains 100 phr of a mixture of solid diene elastomer polymers, the mixture of polymers contains at least one solid polybutadiene (BR) of 10 to 50 phr, having a weight average molecular weight Mw of 300,000 g / mol to 600,000 g / mol, and contains at least one solid polybutadiene having a cis double bond content of at least 95%, the elastomer composition contains at least one emulsion-polymerized solid styrene-butadiene copolymer (E-SBR) of 10 to 70 phr, having a Tg of -60°C to -20°C, a Mooney viscosity of 30 to 70 MU at 160°C, and contains at least one emulsion-polymerized solid styrene-butadiene copolymer having a styrene content of 15% to 50%, contains at least one solution-polymerized solid styrene-butadiene copolymer (S-SBR) of 10 to 80 phr chain-functionalized with a multi-branched coupling agent, having a weight average molecular weight Mw of more than 500,000 g / mol, and / or a styrene content of 25% to 50% and a vinyl content of 10% to 50%, and / or a Tg of -50°C to -20°C, and / or has a Mooney viscosity of 60 to 100 MU at 160°C, at least one solution-polymerized solid styrene-butadiene copolymer, At least 40 phr of at least one reinforcing filler, and at least 1.0 phr of at least one vulcanizing agent.

[0191] In a preferred embodiment, the second elastomeric compound is obtained by vulcanizing an elastomeric composition which contains 0 to 20 phr of at least one liquid polymer, 5 to 40 phr of at least one resin, and 10 to 60 phr of at least one plasticizing oil, wherein when present, the total of the liquid polymer and resin and the plasticizing oil is 15 to 120 phr, and the elastomeric composition contains 100 phr of a mixture of solid diene elastomeric polymers, wherein the mixture of polymers has a weight average molecular weight Mw of 200,000 g / mol to 600,000 g / mol, and contains 10 to 40 phr of at least one solid polybutadiene (BR) preferably having a cis double bond content of at least 30%, and the elastomeric composition contains 60 to 90 phr of at least one terminally functionalized solution polymerized solid styrene butadiene copolymer (S-SBR) which preferably has a weight average molecular weight Mw of more than 500,000 g / mol, preferably more than 800,000 g / mol, more preferably more than 900,000 g / mol, a styrene content of 25% to 50% and a vinyl content of 10% to 70%, preferably 10% to 50%, a Tg of -50 °C to -10 °C, and / or a Mooney viscosity of 50 to 100 MU at 100 °C, and is continuously produced, at least 50 phr of at least one reinforcing filler, and at least 1.0 phr of at least one vulcanizing agent.

[0192] Description of the tire according to the present invention Referring to FIGS. 1 and 2, reference numeral 1 indicates a motorcycle tire according to the present invention.

[0193] Tire 1 is a rear tire, but the following description applies equally to the front tire, except when a specific reference is made to the rear tire.

[0194] Tire 1 is for a motorcycle defined as a big enduro type having a high engine displacement (equal to, for example, 1000 cm 3 ), a large output (equal to, for example, 100 hp), and a motorcycle mass at the riding position equal to, for example, 200 kg or more.

[0195] Tire 1 generally has a maximum radial section width of 90 to 170 mm (for example, 90 mm to 120 mm for the front tire and 130 mm to 170 mm for the rear tire), and a seating diameter of about 17 inches (43.18 cm) to about 21 inches (53.34 cm) (for example, 19 inches (48.26 cm) to 21 inches (53.34 cm) for the front tire and 17 inches (43.18 cm) to 18 inches (45.72 cm) for the rear tire), and is intended to be mounted on a wheel.

[0196] In tire 1, an equatorial plane "X-X" (FIG. 1) and a rotation axis R (FIG. 2) are defined. A circumferential direction arranged according to the rotation direction of tire 1 and thus parallel to the equatorial plane X-X, and an axial direction r perpendicular to the equatorial plane "X-X" and / or parallel to the rotation axis R are also defined.

[0197] Tire 1 comprises a carcass structure 2 formed by at least one carcass ply 3 of an elastomeric material incorporating a plurality of reinforcing cords made of a fiber fabric material (not shown).

[0198] In the tire of FIG. 1, the carcass structure 2 is of the radial type, i.e., the reinforcing cords of the at least one carcass ply 3 are arranged substantially parallel to each other in the radial direction, i.e., at an angle of 70° to 110°, more preferably 80° to 100°, with respect to the circumferential direction.

[0199] In an embodiment not shown, the carcass structure comprises at least two radially overlapping carcass plies. In this case, the reinforcing cords are essentially parallel to each other in each carcass ply, and in each carcass ply they are oriented in an inclined direction (e.g., at least 45°) with respect to the equatorial plane of the tire and in a direction opposite to the cords of the radially adjacent carcass ply 3 (cross-ply carcass).

[0200] The carcass structure 2 is typically lined with a layer of air-impermeable elastomeric material adapted to ensure airtight sealing of the tire 1 itself once inflated, i.e., a so-called liner, which coats its inner wall.

[0201] Each (or the) carcass ply 3 is shaped according to a substantially toroidal form and has axially facing lateral edges 3a directed towards the respective annular reinforcing structure 4 intended to hold the tire 1 on a corresponding mounting rim (not shown). The annular reinforcing structure 4 is typically called a bead core.

[0202] A tapered elastomeric filler 5 is applied to the outer peripheral edge of the bead core 4, and such tapered elastomeric filler 5 occupies the space defined between each carcass ply 3 and the corresponding folded-back lateral edge 3a of the carcass ply 3.

[0203] In a further alternative embodiment not shown, each carcass ply has its facing lateral edges associated with a specific annular reinforcing structure provided with two annular metal inserts, without flaps.

[0204] The region of the tire 1 comprising the bead core 4 and the elastomeric filler 5 forms the so-called bead 9, and such bead 9 is intended to secure the tire 1 to a rim not shown.

[0205] Preferably, a carcass reinforcement structure may advantageously be provided at a radially outer position of the carcass (whether radial or cross-ply). This reinforcement structure comprises, at least for the crown portion, a crown ply disposed radially outermost with respect to the radially outer carcass ply. Such a crown ply is made of reinforcing elements arranged parallel to each other, and the reinforcing elements are arranged so as to have an angle opposite to that of the reinforcing elements of the radially outermost carcass ply with respect to the equatorial plane. Optionally, the carcass reinforcement structure comprises two plies arranged laterally with respect to the crown ply, facing axially with respect to the equatorial plane and not associated with each bead respectively.

[0206] In one embodiment thereof, the (or each) carcass ply 3 is made by combining a plurality of strips of elastomeric material reinforced by the aforementioned cords.

[0207] The belt structure 6 is applied circumferentially at a radially outer position with respect to the carcass structure 2, and such a belt structure 6 comprises at least one belt layer 6a typically formed from a rubberised fabric or a metal cord.

[0208] Preferably, the belt structure 6 is of the zero-degree type, i.e., the belt layer 6a is made of cords arranged substantially parallel and side by side, forming a plurality of turns. Such turns are substantially oriented (typically at an angle of 0° to 5°) along the circumferential direction, and such a direction is usually referred to as "zero-degree" with reference to its laying with respect to the circumferential direction of the tyre 1.

[0209] Preferably, the belt layer 6a, typically known as "zero-degree", may comprise axially arranged turns of a single cord or a rubberised fabric band with axially arranged cords.

[0210] The cords of the zero-degree belt layer 6a are typically metal cords made from high-carbon steel wire, i.e., steel wire with a carbon content of at least 0.6 - 0.7%. Preferably, these metal cords have high elongation (HE).

[0211] To improve the adhesion between the belt structure 6 and the carcass structure 2, an adhesive layer 7 of an elastomeric material may be provided sandwiched between the two aforementioned structures.

[0212] In different embodiments, the belt structure 6 has two or more belt layers radially superimposed, and each layer consists of an elastomeric material reinforced with cords arranged parallel to each other. The above layers are arranged such that the cords of the first belt layer are oriented obliquely with respect to the equatorial plane of the tire, while the cords of the radially adjacent belt layers have an oblique but intersecting orientation with respect to the cords of the first layer (so-called cross-belt), and the same applies to any other belt layer. Cross-belts typically involve textile cords.

[0213] The tread band (8) is circumferentially superimposed on the belt structure 6, and in the tread band (8), after a shaping operation carried out simultaneously with the vulcanization process of the tire 1, circumferential grooves and transverse grooves arranged to delimit a plurality of blocks according to a geometric shape detailed elsewhere in this specification are typically obtained.

[0214] According to a preferred embodiment, the tread band (8) (and other components of the tire) are made using the elastomeric material defined as above.

[0215] The tread band (8) comprises a central annular portion (A) symmetrically arranged across the equatorial plane (X-X), and a pair of annular shoulder portions (B) symmetrically arranged on both sides with respect to the central annular portion (A) and adjacent to the central annular portion (A).

[0216] The central annular portion (A) extends over a width that includes 70% to 90%, preferably 75% to 85%, of the width of the tread band.

[0217] The tread band (8) is of the cap and base type and has an overall total radial thickness S that may vary between the center and the shoulder, and has a rolling layer (8a) (cap) having a radial thickness S1 at the outermost radial position, and a lower layer (8b) (base) having a radial thickness S2 that is adjacent to the rolling layer (8a) and is disposed at the innermost radial position. The tread band (8) has a total radial thickness S = S1 + S2.

[0218] The rolling layer (8a) extends axially over the entire width of the central annular portion (A), and the lower layer (8b) extends axially over the entire width of the tread band, that is, over the entire width of the central annular portion (A) and over the entire width of each annular shoulder portion (B).

[0219] Each annular shoulder portion (B) extends axially over a width of 5% to 15%, preferably 7.5% to 12.5%, of the width of the tread band, and the entire total radial thickness S of the tread band is made from the lower layer (8b).

[0220] The following Table 1 provides some examples of measured values of the cap extension and the base extension for several types of tires according to the present invention.

[0221]

Table 1

[0222] The tire 1 may further include a pair of sidewalls 10 that are applied laterally on both sides of the carcass structure 2.

[0223] Referring to FIG. 1, the tire 1 has a cross-sectional height "H" measured between the top of the tread band (8) and the seating diameter identified by the reference line "r" passing through the bead 9 of the tire 1 on the equatorial plane "X-X".

[0224] The tire 1 further has a maximum radial cross-sectional width "C" defined by the distance between the ends "E" on both lateral sides of the tread band 8, and a deflection "f" defined by the distance from the line passing through the ends "E" on both lateral sides to the top of the tread band (8), and measured on the equatorial plane "X-X" of the tire 1. The ends "E" on both lateral sides of the tread band (8) may be formed with corners.

[0225] The tire 1 has a "camber ratio" (f / C) defined by the ratio between the deflection "f" and the above-mentioned maximum radial cross-sectional width "C".

[0226] The tire 1 has a ratio of "deflection height to total height" (f / H) given by the ratio between the deflection "f" and the cross-sectional height "H".

[0227] The reference symbols ("H", "XX", "r", "C", "f", "E") cited are shown for the rear tire in FIG. 1, but these reference symbols are the same for the front tire as well.

[0228] Preferably, the deflection "f" of the tire 1 is about 40 mm to about 60 mm.

[0229] The tire 1 has a camber ratio "f / C" of about 0.25 to about 0.35, for example equal to about 0.26.

[0230] The tire 1 has a ratio of deflection height to total height "f / H" of about 0.40 to about 0.60, for example equal to about 0.43.

[0231] In the case of a front tire, the deflection "f" is from about 35 mm to about 60 mm, the camber ratio "f / C" is from about 0.30 to about 0.40, and is equal to, for example, 0.38.

[0232] Still in the case of a front tire, the ratio of the deflection height to the total height "f / H" is from about 0.40 to about 0.60, and is equal to, for example, about 0.53.

[0233] As shown in FIG. 2, the tire 1 according to the present invention is of a knobbed type, that is, the tire 1 includes a plurality of transverse grooves and circumferential grooves that separate a plurality of mutually spaced blocks.

[0234] The blocks and grooves define a tread pattern having a void / full ratio of 0.40 to 0.65, preferably 0.50 to 0.6, equal to 0.51 in the case of a rear tire, for example 170 / 60 / R17, and equal to 0.56 in the case of a rear tire, for example 150 / 70 / R18.

[0235] Experimental part Evaluation method Static mechanical properties (load CA1 at 100% elongation, load CA3 at 300% elongation) according to the UNI6065:2001 standard were measured at 23°C for samples of an elastomeric material vulcanized at 170°C for 10 minutes.

[0236] The dynamic mechanical properties E’, E” and loss tangent were measured using an Instron model 1341 dynamic device in tension-compression mode as described in this specification. A crosslinked material (at 170 °C for 10 minutes) having a cylindrical shape (length = 25 mm, diameter = 14 mm) was pre-pressed with a compression of up to 25% longitudinal strain relative to the initial length and maintained at a predetermined temperature of 23 °C or 70 °C throughout the test. A dynamic sinusoidal strain with an amplitude of ±3.5% relative to the length under preload was applied to the test piece at a frequency of 10 Hz or 100 Hz. The dynamic mechanical properties were represented by the dynamic elastic modulus (E’), the dynamic viscosity coefficient (E”), and the loss tangent (loss ratio). The loss tangent value was calculated as the ratio between the dynamic viscosity coefficient (E”) and the dynamic elastic modulus (E’). For samples of the above-mentioned elastomeric material vulcanized at 170 °C for 10 minutes, the hardness (at 23 °C) in IRHD degrees was measured according to the ISO 48:2007 standard.

[0237] Preparation of Compounds The base compounds MB1 (INV), MB2 (REF), and the cap compounds MC1 (INV) and MC2 (REF) were prepared starting from the compositions detailed in Table 2 below.

[0238] [Table 2]

[0239] NR is natural rubber (standard Thai rubber STR20 from Thaiteck Rubber).

[0240] Tufdene E680 (S-SBR) is a solution-polymerized styrene-butadiene polymer extended with 37.5 parts of TDAE oil per 100 parts of dry polymer (107.3 phr of Tufdene E680 contains 78 phr of dry polymer).

[0241] SBR1739 is Buna® SB1739 from Schkopau, an E-SBR produced by low-temperature emulsion polymerization using a mixed rosin / fatty acid soap. SBR1739 is plasticized with 37.5 parts of TDAE oil related to solid rubber (60.5 phr and 76 phr of Buna® SB1739 contain 44 phr and 55.3 phr of dry polymer respectively).

[0242] YB03 Asaprene is a low-cis functionalized polybutadiene polymer.

[0243] SBR1723 is an emulsified styrene-butadiene polymer obtained by low-temperature polymerization using a mixture of rosin acid and fatty acid soap as an emulsifier, oil-extended with 37.5 parts of TDAE oil at a Tg of about -50 °C.

[0244] HPR620 is prepared in solution as described in SG10201800553S(A) in a continuous process, functionalized in the chain with a polyorganosiloxane multi-branched coupling agent, having a weight average molecular weight of about 1,000,000 g / mol, a styrene content of about 40%, a vinyl content of about 25%, a Tg of about -33 °C, and a Mooney viscosity of about 80 MU (Mooney viscosity ML(3+4) 160 °C), and is an oil-extended styrene-butadiene polymer with 25 parts of TDAE oil related to solid rubber (32.5 phr of HPR620 contains 26 phr of dry polymer).

[0245] BR is Europrene® Neocis BR60, a polybutadiene having a high cis content (minimum 97%) produced in solution using a neodymium organometallic catalyst.

[0246] N234 is a high surface area carbon black (STSA 112 m 2 / g).

[0247] CRX1391 is a high surface area carbon black (STSA 156 m 2 / g).

[0248] PERKASIL 408 is PERKASIL® KS408, which is precipitated silica with a high surface area (BET 175 m 2 / g).

[0249] ZEOSIL 1165 MP is silica in the form of microbeads with a high specific surface area BET of 165 m 2 / g.

[0250] ULTRASIL 7000 is precipitated silica with a high surface area (BET 175 m 2 / g).

[0251] RICON 100 is a low molecular weight (Mn 4500) liquid (styrene 25%) butadiene styrene copolymer (PBS) with a Tg of -57 °C.

[0252] TDAE is a treated distilled aromatic extract that is an aromatic oil plasticizer and is Vivatec® 500 (plasticizer).

[0253] POLYVEST 130 is a stereospecific, low-viscosity, non-saponifiable liquid polybutadiene having a high content of 1,4-cis double bonds (1,4-cis double bonds 77%, 1,4-trans double bonds 22%, 1,2-vinyl double bonds 1%), a Tg of -99 °C, and a weight average molecular weight of about 12,000 g / mol.

[0254] TOF is the plasticizer tri-(2-ethylhexyl)-phosphate.

[0255] RESIN 2495 is a terpene resin.

[0256] RASINA CUMARON is a coumarone resin.

[0257] RHENOSIN TT90 is an adhesion-promoting and dispersing hydrocarbon resin.

[0258] NOVARES TT30 is a hydrocarbon resin produced by the polymerization of C9 / C10 unsaturated aromatic hydrocarbons.

[0259] α-Methylstyrene resin is a thermoplastic resin.

[0260] Zinc neodecanoate 50 is a zinc salt of neodecanoic acid.

[0261] RHENOGRAN ZNO is zinc oxide.

[0262] ACID GRAS SARE DE ZINC is a zinc salt of fatty acids.

[0263] Liquid silane is SI69 which is bis[3-(triethoxysilyl)propyl] polysulfide.

[0264] Wax is BMO1 which is a mixture of N-paraffin and isoparaffin.

[0265] 6PPD is N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine which is an antioxidant.

[0266] Sulfur is Lanxess' Rhenocure® IS90-20 which is a mixture of 90:10 ratio of insoluble / soluble sulfur with 20% oil added.

[0267] TBBS is N-tert-butyl-2-benzothiazylsulfenamide.

[0268] MBTS80 is dibenzothiazyl disulfide.

[0269] DURALINK TS is sodium hexamethylene-1,6-bis(thiosulfate) salt.

[0270] TBZTD is tetrabenzylthiuram disulfide (Perkacit® TBzTD).

[0271] An elastomer compound was prepared according to the following process.

[0272] Using a closed mixer (Banbury, Intermix, or Brabender), the components were mixed in two steps.

[0273] In the first step (1), all raw materials were introduced except for the vulcanizing agent and accelerator. Mixing was continued for a maximum of 5 minutes until the temperature reached approximately 145°C. Then, in the second step (2) carried out again using the closed mixer, the vulcanizing agent and accelerator were added and mixing was continued for approximately 4 minutes while maintaining the temperature below 100°C. The compound was then removed. After cooling, and at least 12 hours after preparation, some samples of the compound were pressed and vulcanized at 170°C for 10 minutes to obtain specimens useful for evaluating mechanical characteristics.

[0274] Properties of the Compound The main static and dynamic properties and hardness of the aforementioned elastomer compound, measured by the above method, are shown in Figure 3 below.

[0275] [Table 3]

[0276] The compounds used to produce the tire according to the present invention were MB1 and MC1. While MC1 constituted the central annular portion (A) on the radially outer side of the tread band, MB1 constituted the inner lower layer on the surface of the annular shoulder portion (B) (see the following comparative test).

[0277] It can be seen from Table 3 that the compounds MB1 and MC1, which are suitable for producing the tire of the present invention, have significantly different properties compared to the previous compounds MB2 of the lower layer and the previous compounds MC2 of the tread layer used in the conventional cap and base tread bands (see tire REF1 below).

[0278] Specifically, it was found that the base compound MB1 and the cap compound MC1 had significantly lower IRHD hardness and elastic modulus value E' compared to the compounds MB2 and MC2, respectively, under all test conditions.

[0279] The Applicant understood that the tread band of this tire behaved rather homogeneously in use, as if it were formed from a single material having equal coefficients and hysteresis in various parts of the tread for the operating conditions, despite the simultaneous presence of different compounds.

[0280] As demonstrated by the values of E' and loss tangent in the various regimes shown in Table 3 herein, this phenomenon was highlighted by the measurement of the coefficients and hysteresis of different compounds, which were carried out under the actual conditions where the different compounds acted in specific parts of the tread band where they were located.

[0281] In this regard, the dynamic mechanical properties of this compound were evaluated at different levels of dynamic stress (sample stress at frequencies of 10 Hz and 100 Hz) and different temperatures (23 °C and 70 °C) to reproduce the conditions that this compound would experience in road and off-road driving.

[0282] Specifically, considering road driving, it was possible to identify the following possible thermal regimes during operation, and the relative measurement conditions of the modules, as schematized in Table 4 below.

[0283] [Table 4]

[0284] As can be seen from Table 3, under these conditions (i.e., 100 Hz, 23 °C for the shoulder and 10 Hz, 23 °C for the core), the shoulder compound (MB1) and the core compound (MC1) had practically the same elastic modulus E' (7.77 vs. 7.79).

[0285] Instead, considering off-road operation, it was possible to identify the following possible thermal regimes during operation, and the relative measurement conditions of the module, as schematized in Table 5 below.

[0286]

Table 5

[0287] In off-road operation, the central annular portion was at a high temperature, but the stress was macro (engaging blocks) rather than micro (lateral fluctuations), and thus the measurement frequency was 10 Hz.

[0288] As can be seen from Table 3, under these conditions (i.e., 100 Hz, 70 °C for the shoulder and 10 Hz, 70 °C for the core), the shoulder compound (MB1) and the core compound (MC1) had very similar elastic moduli E' (4.90 vs. 5.20).

[0289] Comparative tests The applicant of the present application produced an example of a rear tire 1 that is 170 / 60 R17 according to an embodiment of the present invention, specifically having the cap and base configurations illustrated in FIG. 1 and the tread pattern illustrated in FIG. 2.

[0290] The cap layer was made of the MC1 compound, while the base layer was made of the MB1 compound. This tire is indicated as INV below.

[0291] Two reference rear tires, designated REF1 and REF2, were further produced. - In REF1, the cap layer and the base layer extended annularly and axially over the entire width of the tread band and consisted of MC2 and MB2, respectively. - In REF2, the cap layer and the base layer were arranged according to the present invention and consisted of MC2 and MB1, respectively.

[0292] An outdoor test was conducted to compare the tire of the present invention with tires REF1 and REF2.

[0293] Tire REF1 is a big enduro type manufactured by the applicant, and its excellent off-road behavior, as well as its behavior on dry and wet road surfaces, which is considered satisfactory, was highly evaluated by customers.

[0294] Tire REF2 was a prototype made for the purpose of comparing the effects of the characteristics of the cap compound and the base compound on the performance of a tire having the same tread structure (cap and base arranged according to the present invention).

[0295] The relevant measured values of the tread bands and their components of tire INV of the present invention and comparison tires REF1 and REF2 are shown in Table 6 below.

[0296]

Table 6

[0297] Tires (inflated to the same inflation pressure) were mounted on the rear wheel of a motorcycle BMW GS1250R, and the same tires were mounted on the front wheel under substantially the same environmental conditions for testing.

[0298] The front tire had a size of 120 / 70R19 with a 3.00×19 rim, and an inflation pressure of 2.0 bar for off-road tests and 2.5 bar for road tests. The rear tire had a size of 170 / 60R17 with a 4.50×17 rim, and an inflation pressure of 2.0 bar for off-road tests and 2.9 bar for road tests.

[0299] By asking the driver for their opinions, the behavior of the INV, REF1, and REF2 tires on both (dry and wet) roads and off-road was evaluated. Specifically, the items listed in Tables 7, 8, and 9 below, which also show the opinions stated by the driver, were evaluated. Road tests were conducted on both dry and wet roads along routes with straight sections and curves. Off-road tests were conducted by running several times on a pre-set length of straight stretch prepared on muddy and sandy ground that replicated conditions that might be found in a natural environment, and keeping the ground as homogeneous as possible after each test. Two sensors were installed on the straight line to determine when the motorcycle entered and exited, and the latter sensor was equipped with suitable instruments (GPS sensor, engine throttle valve opening sensor, and speed sensors for both wheels).

[0300] Table 7 relates to the tests on dry roads. Table 8 relates to the tests on wet roads. Table 9 relates to the off-road tests.

[0301] In Tables 7 to 9, "=" indicates a score equivalent to that obtained with the REF1 tire, and "+" and "-" indicate an improvement or deterioration compared to the REF1 tire.

[0302]

Table 7

[0303]

Table 8

[0304]

Table 9

[0305] Tables 7 and 8 show, along with the behavior of REF1 tires in other evaluated items, how the INV tires unexpectedly generally resulted in improved road surface performance compared to the road surface performance of REF1 tires, regarding comfort and handling especially in contact with particularly dry road surfaces and grip on wet roads. On the other hand, it was found that REF2 tires, whose cap compound MC2 did not have the characteristics of the cap compound MC1 of the present invention, were deteriorating (pejorative).

[0306] Therefore, the Applicant has demonstrated that it is actually possible to obtain a surprisingly improved performance on both dry and wet road surfaces by using a specific compound in combination with the specific configuration employed in the tire of the present invention.

[0307] Instead, Table 9 also highlighted an unexpected improvement in off-road performance for all the items tested. This improvement was not foreseeable and far exceeded the expectations of the Applicant, who had set out to maintain the excellent off-road behavior of the reference tire (REF1).

Claims

1. A tire (1) for a road / off-road motorcycle (big enduro), comprising a tread band (8) with a total radial thickness S, said tread band (8) including a plurality of blocks and grooves defining a void / solid ratio of 0.40 to 0.65 in said tread band (8), said tread band (8) comprising a central annular portion (A) symmetrically disposed across the equatorial plane (X-X), and a pair of annular shoulder portions (B) symmetrically disposed on both sides with respect to said central annular portion (A) and adjacent to said central annular portion (A). - Said central annular portion (A) extends axially over a width of 70% to 90% of the width of said tread band, and includes a rolling layer (8a) with a radial thickness S1 at the outermost radial position, and a lower layer (8b) with a radial thickness S2 adjacent to said rolling layer (8a) and disposed at the innermost radial position, said tread band (8) having a total radial thickness S = S1 + S2. Said rolling layer (8a) extends axially over the entire width of said central annular portion (A), and said lower layer (8b) extends axially over the entire width of said central annular portion (A) and over the entire width of each annular shoulder portion (B). - Each annular shoulder portion (B) extends axially over a width of 5% to 15% of the width of said tread band, and is made from said lower layer (8b) over the entire total radial thickness S of said tread band. Said rolling layer (8a) includes a first elastomeric compound characterized by a modulus of elasticity E' of 5.00 to 6.50 MPa, said lower layer (8b) includes a second elastomeric compound characterized by a modulus of elasticity E' of 3.50 to 4.60 MPa, said modulus of elasticity E' being measured at 70 °C and 10 Hz according to the method described in the experimental part, and the percentage ratio between said modulus of elasticity E' of said second compound and said modulus of elasticity E' of said first compound being 70% to 90%. A tire (1) for a road / off-road motorcycle (big enduro).

2. The tire according to claim 1, wherein the total radial thickness S of the tread band (8) is 10 mm to 20 mm, preferably 12 mm to 16 mm.

3. The tire according to claim 1 or 2, wherein the thickness S1 of the rolling layer (8a) in the central annular portion (A) is 9 mm to 17 mm, preferably 11 mm to 15 mm, and the thickness S2 of the lower layer (8b) in the central annular portion (A) is 0.8 mm to 4 mm, more preferably 1.0 mm to 3 mm.

4. The tire according to any one of claims 1 to 3, wherein the central annular portion (A) extends axially over a width of 75% to 85% of the width of the tread band, and each annular shoulder portion (B) extends axially over a width of 7.5% to 12.5% of the width of the tread band.

5. The tire according to any one of claims 1 to 4, wherein the percentage ratio of the elastic modulus E' of the second compound to the elastic modulus E' of the first compound is 75% to 90%, preferably 80% to 85%.

6. The tire according to any one of claims 1 to 5, wherein the difference between the elastic modulus E' of the first compound and the elastic modulus E' of the second compound is 0.3 to 2.3 MPa, preferably 0.4 to 1.5 MPa, more preferably 0.6 to 1.1 MPa.

7. The tire according to any one of claims 1 to 6, wherein the first elastomeric compound is characterized by an elastic modulus E' of 5.00 to 6.00 MPa, preferably 5.00 to 5.50 MPa, and the second elastomeric compound is characterized by an elastic modulus E' of 4.00 to 4.50 MPa, preferably 4.20 to 4.40 MPa.

8. The first elastomeric compound is characterized by a loss tangent of 0.220 to 0.280, preferably 0.230 to 0.270, and the second elastomeric compound is characterized by a loss tangent of 0.120 to 0.180, preferably 0.135 to 0.150, and the loss tangent is measured at 70 ° C. and 10 Hz. The tire according to any one of claims 1 to 7.

9. The first elastomeric compound is characterized by an IRHD hardness of 66 to 76, preferably 68 to 74, and the second elastomeric compound is characterized by an IRHD hardness of 63 to 73, preferably 65 to 71, and the IRHD hardness is measured at 23 ° C. The tire according to any one of claims 1 to 8.

10. - The first elastomeric compound is characterized by a load CA1 at 100% elongation of 1.7 to 2.3 MPa, preferably 1.9 to 2.1 MPa, and / or a load CA3 at 300% elongation of 7.7 to 10.5 MPa, preferably 8.6 to 9.5 MPa. - The second elastomeric compound is characterized by a load CA1 at 100% elongation of 1.7 to 2.3 MPa, preferably 1.9 to 2.1 MPa, and / or a load CA3 at 300% elongation of 8.6 to 11.7 MPa, preferably 9.7 to 10.7 MPa, and the load CA1 and the load CA3 are measured at 23 ° C. according to the UNI6065: 2001 standard. The tire according to any one of claims 1 to 9.

11. The first elastomeric compound for the rolling layer (8a) is obtained by vulcanization of an elastomeric composition, and the elastomeric composition is 0 to 30 phr of at least one liquid polymer, 0 to 20 phr of at least one resin, 10 to 60 phr of at least one plasticizer oil, and If present, the total of the liquid polymer and resin and the plasticizer oil is 20 to 90 phr, The elastomeric composition is containing 100 phr of a mixture of solid diene elastomer polymers, said mixture of polymers being at least one solid polybutadiene (BR) of 10 to 50 phr, having a weight average molecular weight Mw of 300,000 g / mol to 600,000 g / mol, and containing at least one solid polybutadiene having a cis double bond content of at least 95%, said elastomer composition being at least one emulsion polymerized solid styrene butadiene copolymer (E-SBR) of 10 to 70 phr, having a Tg of -60 °C to -20 °C, having a Mooney viscosity of 30 to 70 MU at 160 °C, and at least one emulsion polymerized solid styrene butadiene copolymer having a styrene content of 15% to 50%, at least one solution polymerized solid styrene butadiene copolymer (S-SBR) of 10 to 80 phr chain functionalized with a multi-branched coupling agent, having a weight average molecular weight Mw of more than 500,000 g / mol, and / or, a styrene amount contained at 25% to 50% and a vinyl amount contained at 10% to 50%, and / or, having a Tg of -50 °C to -20 °C, and / or, at least one solution polymerized solid styrene butadiene copolymer having a Mooney viscosity of 60 to 100 MU at 160 °C, at least one reinforcing filler of at least 40 phr, and at least one vulcanizing agent of at least 1.0 phr, the tire according to any one of claims 1 to 10.

12. said second elastomer compound for said lower layer (8b) being obtained by vulcanization of an elastomer composition, said elastomer composition being 0 to 20 phr of at least one liquid polymer, and 5 to 40 phr of at least one resin, comprising at least one plasticizing oil in an amount of 10 to 60 phr, and if present, the total of the liquid polymer and resin and the plasticizing oil is 15 to 120 phr, said elastomer composition comprising 100 phr of a mixture of solid diene elastomer polymers, said polymer mixture comprising at least 10 to 40 phr of at least one solid polybutadiene (BR) preferably having a weight average molecular weight Mw of 200,000 g / mol to 600,000 g / mol and a cis double bond content of at least 30%, said elastomer composition at least 60 to 90 phr of at least one terminally functionalized solution-polymerized solid styrene-butadiene copolymer (S-SBR) preferably having a weight average molecular weight Mw of more than 500,000 g / mol, a styrene amount of 25% to 50% and a vinyl amount of 10% to 70%, a Tg of -50°C to -10°C, and / or a Mooney viscosity of 50 to 100 MU at 100°C, and being continuously produced, at least one reinforcing filler in an amount of at least 50 phr, at least one vulcanizing agent in an amount of at least 1.0 phr, the tire according to any one of claims 1 to 11.

13. The tire according to any one of claims 1 to 12, mainly for off-road use.

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