Front tire for motorcycles

Abstract

A front tyre (1) for a motorcycle wheel is described as comprising an equatorial plane (XX) and a tread band (8), the tread band (8) having a total axial extension (L) and comprising a radially inner portion (12) made of a first vulcanised elastomeric material and a radially outer portion (11), the radially outer portion (11) comprising: a1) a central annular portion (L1) arranged across the equatorial plane (XX) of the tire (1) and made of a first vulcanized elastomeric material; a2) A pair of lateral annular portions (L2, L3) made of a second vulcanized elastomer material, arranged on both sides of the central annular portion (L1) with respect to the equatorial plane (XX) of the tire (1). In the tire (1), a ratio R1 between the dynamic modulus of elasticity E' of the second vulcanized elastomeric material measured at a frequency of 10 Hz and 23°C and the dynamic modulus of elasticity E' of the first vulcanized elastomeric material measured at a frequency of 10 Hz and 23°C is between 0.6 and 1.2. In the tire (1), the ratio R2 between the tan δ of the second vulcanized elastomeric material measured at a frequency of 10 Hz and 70°C and the tan δ of the first vulcanized elastomeric material measured at a frequency of 10 Hz and 23°C is comprised between 0.6 and 1.2.

Description

Technical Field

[0001] The present invention relates to a front tire for a motorcycle.

[0002] In particular, the present invention relates to motorcycle tires in the "super sports" and / or "hyper sports" segments that are also used on race tracks and involve large displacements (e.g., 600 or 1000 cm 3 3 or more) and / or large outputs (e.g., 200 horsepower or more).

Background Art

[0003] Motorcycle tires are known from, for example, European Patent Application Publication No. 2662226 (A1) and International Publication No. 2019 / 082012.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Recently, there has been an observed trend of large-output super sports or hyper sports motorcycles being introduced into the market. In fact, for example, there are motorcycles for general roads with a displacement of 1000 cm 3 3 or more and an output of 200 horsepower or more in the market.

[0005] The applicant has noticed an increasing demand for high-performance tires for both demanding sports driving (e.g., achievable on a track) and, in particular, year-round use of motorcycles on general roads in adverse weather conditions.

[0006] In this regard, the applicant has observed a recent trend in which users seek tires mounted on supersport motorcycles that combine drivability and performance under extreme handling and speed conditions on dry and / or hot surfaces (hereinafter also referred to as "hot conditions") with drivability and road-holding performance in wet or damp conditions and / or cold weather or suboptimal road conditions (hereinafter also referred to as "cold conditions"), while maintaining tire performance as consistently as possible over long periods.

[0007] Meeting such contrasting requirements with a single pair of tires is a particularly challenging task, as typically different types of measures are taken for each of the above requirements, applying solutions appropriate to the specific problem, but these solutions are contrasting to each other.

[0008] To improve driving performance and capabilities on dry and / or hot ground, as well as in wet or damp conditions and / or cold weather or suboptimal road surfaces, it is particularly necessary to ensure optimal ground contact under these different driving conditions.

[0009] To improve tire grip, it is possible to use so-called soft vulcanized elastomer materials to create the tread band, which best adapt to the roughness of the road surface by reflecting its irregular profile. These vulcanized elastomer materials typically feature a low modulus of elasticity and / or high hysteresis.

[0010] However, the applicant observed that if the vulcanized elastomer material is too soft, the stability when driving on a straight course decreases, and the tire's fuel efficiency decreases.

[0011] To overcome the aforementioned problems, tires made from different vulcanized elastomer materials have been proposed. Typically, a softer vulcanized elastomer material is used for the shoulder, and a less soft vulcanized elastomer material is used for the crown.

[0012] A tire configured in this manner is described, for example, in European Patent No. 2662226.

[0013] However, in relation to this configuration of the tread band, the applicant has observed that the driving performance and performance of the tire under "low temperature" usage conditions tend to decrease, particularly when used on wet roads, and that the tire's performance is significantly impaired.

[0014] To attempt to satisfy the aforementioned contrasting requirements in a single pair of tires, tires have also been proposed that have tread bands made of different vulcanized elastomer materials, typically vulcanized elastomer materials with a high carbon black filler content in the shoulders, and several vulcanized elastomer materials with a high white filler content in the crown and intermediate annular portions of the tread bands.

[0015] For example, as described in International Publication No. 2019 / 082012 in the name of the present applicant, all of this is combined with the proper distribution and arrangement of grooves in the tread band at the interface between vulcanized elastomer materials of different compositions.

[0016] In the pursuit of continuous improvement for motorcycle tires, particularly front tires, the applicant has set itself a dual challenge: to improve the drivability and grip performance of front tires under the aforementioned "low temperature" operating conditions on both dry and wet surfaces, while simultaneously maintaining an excellent level of drivability and performance under "high temperature" operating conditions.

[0017] The applicant has found that these two challenges can be achieved by adopting a so-called "cap-and-base" tread band configuration for the front tire and by using a vulcanized elastomer material that has appropriate dynamic mechanical properties under both "low-temperature" and "high-temperature" tire operating conditions.

[0018] In particular, the applicant found that it was necessary to adopt the following provisions simultaneously for this purpose. i) Configuration of the radially outer portion of a tread band of a type comprising a central annular portion positioned across the equatorial plane of the tire and a pair of transverse annular portions positioned on both axial sides of the central annular portion, ii) Using a first vulcanized elastomer material that is more rigid in the radially inner portion of the tread band and in the central annular portion of the radially outer portion of the tread band, and using a second vulcanized elastomer material that is softer in the transverse annular portion of the radially outer portion of the tread band, and iii) The first and second vulcanized elastomer materials shall be materials having specific mechanical stiffness properties correlated with the dynamic modulus E' under "low temperature" usage conditions, and specific mechanical properties of hysteresis correlated with tanδ under "high temperature" usage conditions of the tire.

[0019] In this regard, the applicant has found that in order to achieve the aforementioned dual objectives, it is necessary to evaluate the dynamic mechanical properties of the vulcanized elastomer materials used to fabricate different portions of the tread band in a distinct manner for each elastomer material, and under specific stress and temperature conditions that correlate with the actual usage conditions of each material, which is subjected to different types of stress and temperature depending on its position in the tread band during front tire use.

[0020] As far as the “low temperature” use of tires is concerned, the applicant has found that, in particular, for all elastomer materials that make up the tread band, the dynamic mechanical property that predicts the behavior of the front tire under such usage conditions is the dynamic modulus of elasticity E', measured at a frequency of 10 Hz and 23°C.

[0021] Conversely, with respect to the "high temperature" use of the front tire, the applicant has determined that the dynamic mechanical properties that predict the behavior of the tire under such usage conditions are, - For the first vulcanized elastomer material of the radially inner part and the central annular part of the radially outer part of the tread band, at a frequency of 10 Hz and 23 °C, and - For the second vulcanized elastomer material of the lateral annular part of the radially outer part of the tread band, it was found that they are the tanδ measured at a frequency of 10 Hz and 70 °C, respectively.

[0022] Thereby, the applicant has surprisingly found that the desired maintenance of the drivability and grip performance under the aforementioned "high temperature" operating conditions, and the improvement of the drivability and grip performance under the aforementioned "low temperature" operating conditions of the front tire are the following dynamic mechanical properties: - The ratio between the "low temperature" dynamic elastic modulus E' of the second vulcanized elastomer material and the "low temperature" dynamic elastic modulus E' of the first vulcanized elastomer material, and - The ratio between the "high temperature" tanδ of the second vulcanized elastomer material and the "high temperature" tanδ of the first vulcanized elastomer material, by maintaining a value close to 1. That is, it has been found that this can be achieved simultaneously by maintaining the "low temperature" dynamic elastic modulus E' and the "high temperature" tanδ of such vulcanized elastomer materials at similar values to each other.

Means for Solving the Problems

[0023] Therefore, the present invention relates to a front tire for a motorcycle comprising a tread band having an equatorial plane and an overall axial extension in the axial direction. The tread band is a) A radially outer part, a1) A central annular part arranged across the equatorial plane of the tire and made of the first vulcanized elastomer material, and a2) A pair of lateral annular parts arranged on both sides of the central annular part with respect to the equatorial plane of the tire, and a pair of lateral annular parts made of the second vulcanized elastomer material. b) A radially inner portion extending along the entire axial extension of the tread band, below the radially outer portion of the tread band, and made of a first vulcanized elastomer material, comprising: The ratio R1 between the dynamic modulus E' of the second vulcanized elastomer material in the transverse annular portion of the radially outer part of the tread band, measured at a frequency of 10 Hz and 23°C, and the dynamic modulus E' of the first vulcanized elastomer material in the central annular portion of the radially outer part and the radially inner part of the tread band, measured at a frequency of 10 Hz and 23°C, is between 0.6 and 1.2. The ratio R2 between the tanδ measured at a frequency of 10 Hz and 70°C for the second vulcanized elastomer material in the transverse annular portion of the radially outer part of the tread band and the tanδ measured at a frequency of 10 Hz and 23°C for the first vulcanized elastomer material in the central annular portion of the radially outer part and the radially inner part of the tread band is between 0.6 and 1.2.

[0024] Basically, in the front tire according to the present invention, i) Effective convergence of the ground "copying" characteristics of the front tire, which correlates with hysteresis characteristics under "high temperature" usage conditions, and ii) It is thought that there is an effective convergence of the characteristics of response homogeneity to stress experienced by the front tire under "low temperature" operating conditions.

[0025] The applicant has found that this convergence of characteristics enables the maintenance of drivability and grip performance over extended periods in dry and / or hot ground conditions, and at the same time, improves drivability and grip performance in wet or damp conditions and / or cold weather or suboptimal road conditions in the “low temperature” usage conditions of motorcycle front tires, specifically motorcycle front tires in the “supersport” and / or “hypersport” segments.

[0026] While we do not wish to be bound by any interpretive theory, the applicant believes that, under "high temperature" usage conditions, the front tire as defined above exhibits substantially uniform hysteresis behavior of the tread band in the shoulder region, i.e., the region subjected to the greatest stress under such usage conditions.

[0027] This result is surprising, as using a relatively "rigid" vulcanized elastomer material in the radially inner portion of the tread band was thought to be not only unsuitable for providing sufficient performance under these usage conditions, but also likely to cause a rapid deterioration of the front tire's performance.

[0028] The applicant has instead found that substantially uniform dynamic and hysteresis behavior of the tread band under “high temperature” operating conditions of the front tire allows for the maintenance of the tire’s “reflective” characteristics and avoids performance degradation and premature wear.

[0029] Conversely, in this case as well, although we do not wish to be bound by any interpretation or theory, the applicant believes that, under "low temperature" usage conditions, the front tire as defined above has substantially uniform dynamic behavior of the tread band as a whole.

[0030] The applicant observed, in particular, extremely homogeneous behavior of the vulcanized elastomer material constituting the tread band under "low temperature" operating conditions for the front tire, and homogeneous behavior that is considered to be essentially correlated with the homogeneity of the "low temperature" dynamic elastic modulus E' of the second vulcanized elastomer material and the first vulcanized elastomer material.

[0031] Therefore, advantageously, the front tire according to the present invention not only enables the maintenance of optimal drivability and grip performance in dry and / or hot ground conditions, typically in use on a race track, but can also achieve improved drivability and grip performance in "low temperature" conditions, typically in use on public roads.

[0032] From a practical standpoint, this translates into an advantage particularly appreciated by users: the fact that the front tires do not necessarily need to be replaced when transitioning from racetrack use to public road use, and vice versa.

[0033] In this specification and the following claims, all numerical entities, such as quantities, parameters, and percentages, should be understood to be preceded in all cases by the term “about,” unless otherwise indicated. Furthermore, all ranges of numerical entities include all possible combinations of the maximum and minimum values, as well as all possible intermediate ranges, in addition to the ranges specifically set forth below in this specification.

[0034] Unless otherwise indicated, all ranges of numerical entities also include the maximum and minimum values.

[0035] For the purposes of this invention, the following definitions apply.

[0036] The term "phr" (an acronym for per hundred parts by weight of rubber) refers to the parts by weight of a given component of an elastomer compound per 100 parts by weight of the elastomer polymer, excluding any possible extender plasticizer oil.

[0037] The terms “elastomer material,” “rubber,” “elastomer polymer,” or “elastomer” are used to describe materials comprising vulcanizable natural or synthetic polymers and reinforcing fillers, such materials, at room temperature, after vulcanization, can be deformed by force and, after the deformable force is removed, can quickly and forcefully return to substantially their original shape and size (according to the standard ASTM D1566-11 definition of standard terms relating to rubber).

[0038] The term "diene polymer" is used to refer to a polymer or copolymer obtained from the polymerization of one or more different monomers, at least one of which is a conjugated diene (conjugated diolefin).

[0039] The terms “compound” or “elastomer compound” are used to refer to a mixture that can be obtained by mixing at least one elastomer polymer with at least one of the additives commonly used in the preparation of tire compounds, and optionally by heating.

[0040] The terms "vulcanizable compound" or "vulcanizable elastomer compound" are used to refer to a vulcanizable elastomer mixture obtained by incorporating all additives, including vulcanizing additives, into an elastomer compound.

[0041] The term "vulcanized elastomer material" is used to refer to a material obtained by vulcanizing a vulcanizable elastomer compound.

[0042] The term "vulcanization" is used to describe the crosslinking reaction of natural or synthetic rubber induced by a crosslinking agent, typically a sulfur-based crosslinking agent.

[0043] The term "vulcanizing agent" is used to describe compounds that can transform natural or synthetic rubber into elastic and strong materials by forming a three-dimensional network of intermolecular and intramolecular bonds. Typical vulcanizing agents are sulfur-based compounds such as elemental sulfur, polymerizable sulfur, bis[(trialkoxysilyl)propyl]polysulfide, thiuram, dithiodimorpholine, and sulfur donors such as caprolactam disulfide.

[0044] The term "vulcanization accelerator" is used to refer to compounds that enable a reduction in the duration of the vulcanization process and / or a decrease in the operating temperature, such as sulfur donors including TBBS, sulfenamides in general, thiazoles, dithiophosphates, dithiocarbamates, guanidines, and thiuram.

[0045] The term "vulcanization activator" is used to describe compounds that further accelerate vulcanization by causing it to occur in a shorter time and, in some cases, at lower temperatures. An example of an activator is the stearate-zinc oxide system.

[0046] The term "vulcanization retarder" is used to refer to compounds that can delay the initiation of a vulcanization reaction and / or suppress undesirable secondary reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0047] The term "reinforcement filler" is used to refer to reinforcement materials typically used in the field, preferably selected from carbon black and "white filler," for the purpose of improving the mechanical properties of tires.

[0048] The term "white filler" is used to refer to conventional reinforcing materials used in the field, selected from conventional silica and silicates, such as preferably amorphous, strongly acid-precipitated silica sand, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicate, kaolin, silicate fibers, phyllosilicate minerals such as sepiolite, palygorskite (also known as attapulgite), montmorillonite, and halloysite, and possibly modified by acid treatment and / or derivatization, as well as mixtures thereof. Typically, white fillers have surface hydroxyl groups.

[0049] The term "motorcycle front tire" is used to describe a tire that has a large curvature ratio (typically 0.35 or greater) and can achieve a large camber angle while riding along a curve.

[0050] The term "curvature ratio" is used to describe the ratio of the distance contained between the radial highest point of the tread band and the maximum width of the tire's radial cross-section (such distances are also indicated as "arrows") to the same maximum width of the tire.

[0051] The term "axial extension" of the tread band or any part thereof is used to refer to the radially outermost profile extension of the tread band or any part thereof in a cross-section of the tire, as determined by the plane containing the tire's axis of rotation.

[0052] The term "axial semi-extension" of the tread band or any part of the tread pattern is used to refer to the radially outermost profile of the tread band or any part of it, extending from the equatorial plane toward the outermost axial end of the tire in a cross-section of the tire, as defined by the plane containing the tire's axis of rotation.

[0053] The term "equator plane" of a tire is used to refer to a plane that is perpendicular to the tire's axis of rotation and symmetrically bisects the tire.

[0054] The term "width" is used to indicate a dimension measured along a direction perpendicular to the equatorial plane.

[0055] The term "tread pattern" is used to describe all parts of the tread band (including sipes) in a plane perpendicular to the tire's equatorial plane and tangent to the tire's maximum diameter. The tread pattern is defined by multiple solid sections separated by sipes and, in some cases, includes grooves.

[0056] The terms “radial” and “axial,” as well as the expressions “radially inward / outward” and “axially inward / outward,” are used to refer to the direction substantially parallel to the equatorial plane of the tire and the direction substantially perpendicular to the equatorial plane of the tire, respectively; that is, the direction substantially perpendicular to the axis of rotation of the tire and the direction substantially parallel to the axis of rotation of the tire, respectively.

[0057] The terms "circumferential" and "circumferential" are used to refer to the direction of the tire's circumferential extension, i.e., the direction of the tire's rolling, and correspond to the direction of a plane that coincides with or is substantially parallel to the tire's equatorial plane.

[0058] The term "circumferential elongation" of a tire, tread band, or part thereof is used to refer to the planar elongation of the radially outermost surface of the tire, tread band, or part thereof, on the plane in contact with the tire.

[0059] The terms "axially inward" and "axially outward" indicate the position of the reference element that is close to the equatorial plane and the position that is farther from the equatorial plane, respectively.

[0060] The term “radial carcass structure” is used to describe a carcass structure in the crown of a tire that comprises multiple reinforcing cords, each oriented substantially along the axial direction. Such reinforcing cords may be incorporated into a single carcass ply or into several (preferably two) carcass plies juxtaposed radially to one another.

[0061] The term "substantially axial" is used to indicate a direction inclined at an angle between 60° and 90° relative to the tire's equatorial plane.

[0062] The term "substantially circumferential" is used to indicate a direction that aligns with an angle between 0° and 20° relative to the tire's equatorial plane.

[0063] The term "static mechanical properties" of a tread compound is used to describe the tensile stress-strain properties of vulcanized and thermoplastic rubbers, measured at a predetermined temperature for a sample of the compound vulcanized at 170°C for 10 minutes, in accordance with UNI standard 6065:2001.

[0064] The term “dynamic mechanical properties” of the tread compound is used to refer to the mechanical properties measured using the Instron Model 1341 dynamic apparatus in tensile-compression mode, as described herein.

[0065] A cylindrical specimen (length = 25 mm, diameter = 18 mm) of cross-linked material was used, and a compressive preload was applied until the longitudinal deformation reached 25% of the initial length. The specimen was maintained at a predetermined temperature (e.g., 23°C and 70°C) for the entire duration of the test. Following a 2-minute waiting period, a mechanical pre-adjustment was performed with a deformation amplitude of 7.5% of the length under preload, at 10 Hz, for 125 cycles. The specimen was then subjected to a dynamic sinusoidal stress with an amplitude of ±3.5% of the length under preload at a predetermined frequency, e.g., 10 Hz. The dynamic mechanical properties are represented by the values ​​of the dynamic modulus of elasticity E' and tanδ (loss coefficient). The tanδ value was calculated as the ratio between the kinematic viscosity coefficient (E'') and the dynamic modulus of elasticity E'.

[0066] The term "overall void-to-rubber ratio" is used to indicate the ratio between the overall surface area of ​​the grooves in a particular annular portion of the tread band (or sometimes the entire tread band) and the overall surface area of ​​the entire tread band.

[0067] The terms “annular portion” or “annular sector” are used to refer to a portion or sector of a tread band that extends circumferentially across the entire tread band and has a predetermined axial extension.

[0068] The distance of an annular tread portion or annular tread sector from the equatorial plane, or the distance between annular portions or annular sectors, is evaluated axially by referring to the center plane of those portions parallel to the equatorial plane, unless otherwise specified.

[0069] The terms "void-to-rubber ratio of the annular portion" or "void-to-rubber ratio of the annular sector," or collectively "void-to-rubber ratio," are used to indicate the ratio between the overall surface of the grooves in the annular portion or annular sector and the overall surface of the annular portion or annular sector itself.

[0070] The term “substantially groove-free” is used to refer to a portion of the tire's tread band, indicating that the “void-to-rubber ratio” defined above is very close to zero or substantially equal to zero in the portion of the tread band under consideration, for example, having a value of less than 0.2%.

[0071] The term "pitch" in tire terminology is used to describe a group of grooves and solid sections arranged to form a substantially identical pattern that repeats on the tread band without interruption along the circumferential extension of the tread band. Along the circumferential extension of the tread band, the pitch may have different circumferential lengths and may be circumferentially offset from one another on either side of the tire's equatorial plane.

[0072] The term "module," referring to the tread band, and more specifically the tread pattern, is used to indicate a portion of the tread pattern that is continuously repeated along the circumferential extension of the tread band itself. A module may still have different circumferential lengths while maintaining the same pattern configuration, and / or may have portions located on either side of the tire's equatorial plane, circumferentially offset along the circumferential extension of the tire itself.

[0073] In this second case, the tires have a "pitch" that is offset from each other circumferentially on both sides of the equatorial plane.

[0074] In one or more of the embodiments described above, the present invention may have one or more of the following preferred features, which can be combined with each other as desired depending on the application requirements.

[0075] Preferably, the ratio R1 between the dynamic modulus E' of the second vulcanized elastomer material of the lateral annular portion of the radially outer portion of the tread band, measured at a frequency of 10 Hz and 23°C, and the dynamic modulus E' of the first vulcanized elastomer material of the central annular portion of the radially outer portion and the radially inner portion of the tread band, measured at a frequency of 10 Hz and 23°C, is between 0.7 and 1.1.

[0076] In this way, it is advantageously possible to achieve optimal characteristics of the homogeneity of the tread band behavior under "low temperature" operating conditions for the front tire, accompanied by a significant improvement in driving and road-holding performance under these operating conditions.

[0077] Preferably, the ratio R2 between the tanδ measured at a frequency of 10 Hz and 70°C for the second vulcanized elastomer material of the transverse annular portion of the radially outer portion of the tread band and the tanδ measured at a frequency of 10 Hz and 23°C for the first vulcanized elastomer material of the central annular portion of the radially outer portion and the radially inner portion of the tread band is between 0.7 and 1.1.

[0078] In this way, it is advantageously possible to maintain or further improve drivability and road-holding performance under "high temperature" operating conditions for the front tires, while having optimal characteristics for the "reflection" of the tread band on the ground under these operating conditions.

[0079] In practice, the shoulder region of the front tire's tread band is formed from a vulcanized elastomer material that is substantially "homogeneous" in terms of its behavior on the road, and in terms of its "high-temperature" deformation capability.

[0080] Preferably, the first vulcanized elastomer material of the central annular portion of the radially outer portion and the radially inner portion of the tread band has a dynamic modulus of elasticity E' measured at a frequency of 10 Hz and 23°C, with an elasticity ranging from 5.7 to 7.1 MPa, more preferably from 6.0 to 6.4 MPa.

[0081] In this way, it is advantageously possible to have appropriate stiffness and support characteristics in the radially inner portion of the tread band under "low temperature" operating conditions for the front tire.

[0082] Preferably, the first vulcanized elastomer material of the central annular portion of the radially outer portion and the radially inner portion of the tread band has a tanδ measured at a frequency of 10 Hz and 23°C, which is between 0.37 and 0.47, preferably between 0.41 and 0.45.

[0083] Advantageously, this favorable characteristic contributes to optimizing, maintaining substantially constant, or improving the drivability and performance of the front tire under "high-temperature" usage conditions on dry and / or hot surfaces when driving along curves.

[0084] Preferably, the second vulcanized elastomer material of the lateral annular portion of the radially outer portion of the tread band has a dynamic modulus of elasticity E' measured at a frequency of 10 Hz and 23°C, with a dynamic modulus of elasticity E' between 5.2 and 6.5 MPa, more preferably between 5.6 and 6.0 MPa.

[0085] Advantageously, this desirable characteristic contributes to achieving optimal homogeneity of the front tire tread band, improving the drivability and performance of the tire under "low temperature" operating conditions.

[0086] Preferably, the second vulcanized elastomer material of the transverse annular portion of the radially outer portion of the tread band has a tanδ measured at a frequency of 10 Hz and 70°C, which is between 0.34 and 0.44 MPa, more preferably between 0.38 and 0.40 MPa.

[0087] Advantageously, this desirable characteristic contributes to maintaining or further improving drivability and road-holding performance under "high-temperature" operating conditions for the front tire, while achieving optimal characteristics of the tread band's "reflection" on the ground under these operating conditions.

[0088] Preferably, the first vulcanized elastomer material for the central annular portion of the radially outer portion and the radially inner portion of the tread band is obtained by vulcanizing an elastomer material comprising at least one elastomerized polymer 100 phr and a white reinforcing filler 70 to 110 phr, more preferably 80 to 100 phr.

[0089] Preferably, the white reinforcing filler contains an amount of 80% by weight or more, more preferably 85% by weight or more, more preferably 90% by weight or more, and more preferably 95% by weight or more, of the total weight of the reinforcing filler, an inorganic material selected from silica, alumina, silicates, hydrotalcite, calcium carbonate, kaolin, titanium dioxide, and mixtures thereof.

[0090] Advantageously, this desirable characteristic contributes to achieving optimal wet grip characteristics in "low temperature" operating conditions for the front tire.

[0091] Preferably, the second vulcanized elastomer material of the transverse annular portion of the radially outer portion of the tread band is obtained by vulcanizing an elastomer material comprising at least one elastomerized polymer 100 phr and a carbon black reinforcing filler 40 to 100 phr, more preferably 50 to 90 phr, and even more preferably 60 to 80 phr.

[0092] Preferably, the reinforcing filler contains carbon black in an amount of 75% by weight or more, preferably 80% by weight or more, more preferably 85% by weight or more, more preferably 90% by weight or more, and more preferably 95% by weight or more, of the total weight of the reinforcing filler.

[0093] Advantageously, this desirable characteristic contributes to achieving optimal grip characteristics under "high temperature" operating conditions for the front tire.

[0094] Preferably, the central annular portion of the radially outer part of the tread band extends transversely along 5-25%, preferably 10-20%, of the axially semi-extended portion of the tread band.

[0095] In this way, it is advantageously possible to achieve optimal stiffness and road-holding characteristics for the front tire under "low-temperature" operating conditions.

[0096] Preferably, the end of the lateral annular portion of the radially outer portion of the tread band, proximal to the equatorial plane, is positioned at a distance from the equatorial plane of at least 10% of the axial semi-extended portion of the tread band itself.

[0097] In this way, it is advantageously possible to achieve optimal drivability and grip performance of the front tires across a wide range of camber angles on both dry and wet or damp surfaces.

[0098] In a preferred embodiment, each of the lateral annular portions of the radially outer portion of the tread band is positioned adjacent to the central annular portion on the axial side, such that it defines an interface separating the central annular portion from the lateral annular portion along the axial direction.

[0099] In this way, it is advantageous to appropriately control the axial transition between the first vulcanized elastomer material and the second vulcanized elastomer material in the tread band in order to achieve the desired dynamic mechanical properties and behavioral homogeneity of the front tire.

[0100] In a preferred embodiment, the aforementioned interface can converge from the inside to the outside of the tread band toward the equatorial plane of the tire.

[0101] In this case, the aforementioned interface can be inclined with respect to the equatorial plane of the tire at an angle preferably between 30° and 50°, more preferably between 35° and 40°.

[0102] In this way, it is advantageous to achieve a gradual axial transition between the first vulcanized elastomer material and the second vulcanized elastomer material in the tread band, thereby achieving optimal dynamic mechanical properties and behavioral homogeneity of the front tire.

[0103] In an alternative, preferred embodiment, the aforementioned interface may be parallel to the equatorial plane of the tire, or it may even extend away from the equatorial plane from the inside to the outside of the tread band.

[0104] In this case, the aforementioned interface can be inclined with respect to the equatorial plane of the tire at an angle preferably between 120° and 140°, more preferably between 125° and 130°.

[0105] Preferably, the lateral annular portion of the radially outer portion of the tread band extends transversely along 75-95%, more preferably 80-90%, of the axially semi-extended portion of the tread band.

[0106] In this way, it is advantageously possible to optimize the drivability and grip performance of the front tires over a wide range of camber angles on both dry and wet or damp surfaces.

[0107] In a particularly preferred embodiment, the central annular portion of the radially outer portion of the tread band is substantially groove-free.

[0108] In this way, the adhesion capability of the first vulcanized elastomer material in the central annular portion of the radially outer portion of the tread band makes it advantageously possible to optimize the drivability and grip performance of the front tire in wet or damp conditions.

[0109] Preferably, each lateral annular portion of the radially outer part of the tread band comprises a first lateral annular sub-portion proximal to the equatorial plane of the tire and a second lateral annular sub-portion distal to the equatorial plane.

[0110] Preferably, the tire has a plurality of grooves formed in a first lateral annular sub-portion of the lateral annular portion of the radially outer portion of the tread band.

[0111] The applicant has experimentally found that these features result in a remarkable synergistic collaboration between the tread pattern configuration in the grooved portions and the mechanical properties of the stiffness of the tread band having the "cap and base" structure defined above, in achieving optimal drivability and performance of the tire on wet and / or cold ground.

[0112] Preferably, the first transverse annular sub-portion of the aforementioned transverse annular portion of the radially outer portion of the tread band extends transversely along 40-65%, more preferably 45-60%, of the axially semi-extended portion of the tread band.

[0113] In this way, the ability of the lateral annular portion of the radially outer part of the tread band, specifically its first lateral annular sub-part, to drain water present beneath the tire's contact area in the region of the tread band most frequently used during "low temperature" operating conditions of the front tire can advantageously optimize the drivability and grip performance of the front tire on wet or damp ground.

[0114] Preferably, the aforementioned plurality of grooves constitute a tread band that defines an overall void-to-rubber ratio of 4% or more and 8% or less, more preferably 4% or more and 5% or less.

[0115] In this way, it is advantageously possible to impart appropriate rigidity to the tread band without limiting its drainage capacity.

[0116] Preferably, the aforementioned plurality of grooves define a void-to-rubber ratio of 0% or more and 30% or less, more preferably 0% or more and 25% or less, in each first lateral annular sub-part of the lateral annular portion of the radially outer portion of the tread band.

[0117] In this disclosure, the value of the void-to-rubber ratio is considered to be calculated by dividing the radially outer portion of the tread band into annular areas having a predetermined transverse extension of, for example, 5 mm, and calculating the ratio value within each annular area.

[0118] In this way, it is advantageously possible to achieve an optimal compromise between the drivability and grip performance under "low temperature" operating conditions in wet or damp conditions and the drivability and grip performance of the front tires under "high temperature" operating conditions.

[0119] In a preferred embodiment, the aforementioned plurality of grooves define an air-to-rubber ratio that increases with distance from the tire's equatorial plane, starting from the aforementioned interface, along the axially semi-extended portion of the tread band, in a first annular sector located axially outward and adjacent to the central annular portion of each first lateral annular sub-portion of the lateral annular portion of the radially outer portion of the tread band.

[0120] Preferably, the aforementioned first annular sector extends transversely from the end proximal to the equatorial plane of the transverse annular portion of the radially outer portion of the tread band, in other words, it extends transversely from a circumferential line defined by the intersection between a plane passing through the boundary surface and the radially outer surface of the tread band. Its proximal end separates the central annular portion and the transverse annular portion of the radially outer portion of the tread band axially along 5-25%, more preferably 10-20%, of the axial half-extension of the tread band.

[0121] Preferably, in the first annular sector described above, the void-to-rubber ratio increases from a minimum value of approximately 0% at the end proximal to the equatorial plane of the transverse annular portion of the radially outer portion of the tread band to a maximum value that falls between 20% and 30% at the axially outer end of the first annular sector.

[0122] Preferably, the axial outer end of the first annular sector is positioned at a distance from the tire's equatorial plane that is at least 13% of the axial semi-extended portion of the tread band.

[0123] More preferably, the axial outer end of the first annular sector is located at a distance from the equatorial plane of the tire, within 15% to 35% of the axial semi-extended portion of the tread band.

[0124] In this way, the synergistic cooperation between the tread pattern configuration and mechanical hysteresis properties of the second vulcanized elastomer material in the lateral annular portion of the radially outer portion of the tread band can advantageously optimize the drivability and grip performance of the front tire in wet or damp conditions.

[0125] Specifically, under "low temperature" operating conditions for the front tire, the lateral annular portion of the radially outer part of the tread band can effectively drain water present beneath the tire's contact area in the tread band region most frequently used during straight-line driving and when driving along curves with a tendency towards low camber angles. Meanwhile, the mechanical hysteresis characteristics of the tread band enable a homogeneous response to the stresses the tire is subjected to under these operating conditions.

[0126] In a preferred embodiment, the aforementioned plurality of grooves are positioned axially outward of each first lateral annular sub-part of the lateral annular portion of the radially outer portion of the tread band, and in a second annular sector adjacent to the aforementioned first annular sector, they define a gap-to-rubber ratio that decreases along the axial extension of the tread band, starting from the aforementioned first annular sector and moving away from the equatorial plane of the tire.

[0127] Preferably, the second annular sector extends transversely from the first annular sector along 15-60%, more preferably 25-50%, of the axial semi-extended portion of the tread band.

[0128] Preferably, in the second annular sector, the void-to-rubber ratio decreases from a maximum of about 25% at the axial outer end of the first annular sector to a minimum of about 0% at the axial outer end of the first lateral annular sub-part of the lateral annular portion of the radially outer portion of the tread band.

[0129] Advantageously, in this preferred embodiment of the present invention, the void-to-rubber ratio decreases as the tire moves away from the equatorial plane, allowing for full utilization of the hysteresis properties of the second vulcanized elastomer material in the case of demanding operation and high camber angles, which are conditions that may be reached under high-temperature conditions during racing / on the racetrack.

[0130] In other words, in this preferred embodiment of the present invention, there is an effective synergistic interaction between the properties of the vulcanized elastomer material in the radially outer portion and the properties of the tread pattern.

[0131] Preferably, the axial outer end of the first lateral annular sub-part of the lateral annular portion of the radially outer portion of the tread band, which coincides with the axial outer end of the second annular sector, is positioned at a distance from the tire's equatorial plane XX of at least 55%, more preferably at least 60%, of the axial half-extension of the tread band.

[0132] In this way, it is advantageously possible to optimize the drivability and grip performance of the tire under "high temperature" operating conditions, and therefore in the absence of wet or damp surfaces, when driving along curves, which tend to be performed at higher camber angles.

[0133] Preferably, the second lateral annular sub-portion of the lateral annular portion of the radially outer portion of the tread band extends transversely along 10-55%, more preferably 20-45%, of the axially semi-extended portion of the tire's tread band.

[0134] In a particularly preferred embodiment, each second lateral annular sub-part of the aforementioned lateral annular portion of the radially outer portion of the tread band substantially does not contain grooves.

[0135] In this way, it is advantageously possible to optimize the drivability and grip performance of the tire under "high temperature" operating conditions, and therefore in the absence of wet or damp surfaces, when driving along curves, which tend to be performed at higher camber angles.

[0136] Preferably, the front tire for motorcycles of the present invention has a transverse curvature ratio of 0.35 or more and 0.50 or less, more preferably 0.39 or more and 0.45 or less, and even more preferably 0.40 or more and 0.44 or less.

[0137] Further features and advantages of the present invention will become more apparent from the following description of some preferred embodiments for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0138] These drawings are schematic and not to scale. [Brief explanation of the drawing]

[0139] [Figure 1] This is a perspective view of a front tire according to a preferred embodiment of the present invention. [Figure 2] This is a schematic, enlarged view of the cross-section of the front tire shown in Figure 1. [Figure 3] This graph shows the trend of the air-to-rubber ratio along the axial semi-expansion of the front tire in Figure 1, and also indicates the position of the circumferential line that separates the central annular portion and the lateral annular portion of the radially outer part of the tread band along the axial direction. [Figure 4]Figure 1 is a schematic plan view of a portion of the tread band of the front tire. [Modes for carrying out the invention]

[0140] In the figure, reference numeral 1 represents, as a whole, a front tire for a motorcycle wheel according to a preferred embodiment of the present invention. This preferably relates to a tire intended for use on the rear wheel of a motorcycle for a large displacement, e.g., a 600cc supersport motorcycle in the "supersport" and / or "hypersport" segment.

[0141] The equatorial plane XX and the axis of rotation (not shown) are defined for tire 1. The circumferential direction (indicated by arrow F pointing in the direction of rotation of tire 1 in Figures 1 and 4) and the axial direction (indicated by axis r perpendicular to the equatorial plane XX in Figure 2) are also defined.

[0142] The tire 1 comprises a carcass structure 2 formed by at least one carcass layer 3 having multiple reinforcing elements (cords). In the embodiment shown in Figure 1, there are two carcass layers 3.

[0143] Carcass structure 2 is typically configured such that its inner wall is coated with a sealing layer, a so-called "liner," which is basically an airtight layer of elastomer material, ensuring an airtight seal of the tire itself when inflated.

[0144] The reinforcing elements included in the carcass layer 3 preferably include woven cords made of fibrous material.

[0145] The fibrous materials used in the manufacture of the cord can be made alone or in mixtures from natural or synthetic fibers selected from rayon, lyocell, polyester (e.g., PEN, PET, PVA), and aromatic polyamides (e.g., aramids such as Twaron® and Kevlar®). More specifically, the fibrous materials for making the cord are preferably selected from polyester, rayon, lyocell, aromatic polyamides, or hybrids formed from two or more of the aforementioned materials.

[0146] The reinforcing elements included in at least one carcass layer 3 are preferably arranged radially, i.e., according to angles between 70° and 110°, more preferably between 80° and 100°, with respect to the circumferential direction.

[0147] At least one carcass layer 3 is shaped substantially according to a toroidal form and is engaged with at least one annular reinforcing structure by its peripheral edges 3a on both sides.

[0148] In particular, the side edges 3a on both sides of at least one carcass layer 3 can be folded back around an annular reinforcing structure, each annular reinforcing structure comprising one or more metallic annular bead cores 4 and tapered elastomer fillers 5 that occupy the space defined between the carcass layer 3 and the corresponding folded side edges 3a of the carcass layer 3.

[0149] The area of ​​the tire comprising the bead core 4 and the filler material 5 forms a so-called bead 9, which is intended to secure the tire 1 to a corresponding mounting rim (not shown).

[0150] In embodiments not shown, at least one carcass layer 3 is made by joining multiple pieces of elastomer material reinforced by the aforementioned code, and has side edges on both sides that are associated without folding with a special annular reinforcement structure having two annular inserts. A filler made of elastomer material can be positioned axially outward with respect to the first annular insert, while a second annular insert can be positioned axially outward with respect to the end of the carcass layer. Finally, a further filler can be provided axially outward with respect to this second annular insert, although it does not necessarily need to be in contact with it, to complete the fabrication of the annular reinforcement structure.

[0151] A belt structure 6, typically comprising at least one belt layer 6a formed of a rubber-coated cord, is applied circumferentially on the carcass structure 2 at a radially outward position.

[0152] Preferably, layer 6a is made of cords arranged substantially parallel and in parallel to form multiple windings. Such windings are oriented substantially circumferentially (typically at an angle between 0° and 5°), such orientation is usually referred to as "zero degrees" with respect to the arrangement laid relative to the circumferential direction of the tire.

[0153] Preferably, the layer 6a, typically referred to as the "zero degree," may comprise windings of a single cord adjacent in the axial direction, or windings of a rubber-coated cloth band having axially adjacent cords.

[0154] The cord of layer 6a is a woven or metal cord. Preferably, such a cord is made of metal consisting of high-carbon steel wire, i.e., steel wire with a carbon content of at least 0.6 to 0.7%.

[0155] Preferably, such metal cords have high elongation (HE).

[0156] To improve the adhesion between the belt structure 6 and the carcass structure 2, an adhesive layer 7 made of an elastomer material (not shown) may be sandwiched between the two structures.

[0157] In embodiments not shown, the belt structure 6 may consist of at least two radially juxtaposed layers. These layers are arranged such that the cords of the first belt layer are oriented obliquely with respect to the circumferential direction of the tire, and the cords of the second layer are also oriented obliquely, but intersect substantially symmetrically with respect to the cords of the first layer.

[0158] The tread band 8 is circumferentially superimposed on the belt structure 6, and the tread band 8 has longitudinal and transverse grooves formed on the tread band 8, typically arranged to define a desired tread pattern after a molding process that is performed simultaneously with the vulcanization of the tire.

[0159] Figures 1, 2, and 4 show, as non-limiting examples, tread patterns comprising a plurality of grooves 13, 14 arranged in various ways on both sides of the equatorial plane XX of the tire 1, and satisfying the requirements of the air-to-rubber ratio and the fluctuating trend of groove distribution according to a preferred embodiment of the front tire 1 of the present invention.

[0160] As better illustrated in Figure 4, the tread pattern comprises modules 15 that are repeated along the direction of circumferential expansion of the tire 1.

[0161] In a preferred embodiment of the front tire 1 shown in Figure 4, the module 15 comprises two pitches P that are circumferentially offset from each other on both sides of the equatorial plane XX of the tire 1.

[0162] The aforementioned module 15 is repeated at least 10 times along the circumferential unfolding of the tire 1, in the case of a tire intended to be mounted on the front wheel of a motorcycle, as in one object of the present invention. Preferably, it is repeated at least 12 times, for example 14 times.

[0163] Preferably, the tread pattern has a substantially L-shape and comprises a first circumferential continuity of the first groove 13 having a tapered portion of its preferred length along the preferred rolling direction F of the tire 1.

[0164] Preferably, the tread pattern includes a second circumferential continuum of a second groove 14, which is sandwiched circumferentially between the first grooves 13 and is preferably tapered along a direction opposite to the preferred rolling direction F of the tire 1.

[0165] Preferably, both the first groove 13 and the second groove 14 are inclined with respect to the equatorial plane XX of the tire 1.

[0166] For simplicity, grooves 13 and 14 are not shown in Figure 2.

[0167] The tire 1 may have a pair of sidewalls 10 applied laterally to both sides of the carcass structure 2.

[0168] The tire 1 has a cross-sectional height H measured between the top of the tread band 8 and the mounting diameter, which is defined by a reference line r passing through the bead of the tire 1, in the equatorial plane XX.

[0169] The tire 1 further has a maximum cross-sectional width C defined by the distance between the axial ends E of the tread band 8 profile, and a curvature ratio defined as the ratio of the distance f of the top of the tread band 8 from a line passing through both ends E of the tread band 8 itself, measured on the equatorial plane of the tire 1, to the maximum width C. The axial ends E of the tread band 8 can be formed by angles.

[0170] Specifically, tire 1 has a cross-section characterized by a large curvature ratio, preferably having a transverse curvature ratio f / C of 0.35 or more and 0.50 or less, more preferably 0.39 or more and 0.45 or less, and even more preferably 0.40 or more and 0.44 or less.

[0171] In a preferred embodiment, the motorcycle front tire 1 of the present invention is intended to be mounted on a front wheel having a chord dimension substantially between 100 and 130 mm.

[0172] Preferably, the distance f between a radially outer point of the tread band 8 and a line passing through both axial ends E of the tread band 8 itself of the tire 1 is substantially between 47 and 55 mm.

[0173] Preferably, the overall height / code ratio (H / C) falls substantially between 0.60 and 0.70.

[0174] In a preferred embodiment, better performance is possible when the tire 1 has a sidewall 10 of considerable height, for example, having a sidewall height ratio (Hf) / H of 0.3 or more, more preferably 0.35 or more.

[0175] According to the present invention, the tread band 8 is of the so-called "cap and base" type and is made of two different vulcanized elastomer materials having the above-mentioned properties.

[0176] In the illustrated preferred embodiment, the tread band 8 has a fully axially extended portion L, a) Radially outer portion 11, a1) A central ring portion L1 is positioned across the equatorial plane XX of tire 1, a2) The tire 1 comprises a radially outer portion 11 which includes a pair of lateral annular portions L2 and L3 positioned on both sides of the central annular portion L1 with respect to the equatorial plane XX of the tire 1.

[0177] As outlined above, the central annular portion L1 is made of the first vulcanized elastomer material mentioned earlier, while the lateral annular portions L2 and L3 of the tread band 8 are made of the second vulcanized elastomer material mentioned above.

[0178] In the illustrated preferred embodiment, the tread band 8 includes a radially inner portion 12 that extends along the entire axial extension of the tread band 8, below the radially outer portion 11 of the tread band 8.

[0179] As outlined above, the radially inner portion 12 of the tread band 8 is made of the aforementioned first vulcanized elastomer material.

[0180] Preferably, the central annular portion L1 of the tread band 8 has an axial extension portion L1 that extends transversely along 5-25%, more preferably 10-20%, of the axial semi-extension portion L / 2 of the tread band 8.

[0181] Preferably, the lateral annular portions L2 and L3 of the tread band 8 have axial extensions that extend transversely along 75-95%, more preferably 80-90%, of the axial semi-extension portion L / 2 of the tread band 8.

[0182] Preferably, as better illustrated in Figure 4, the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8 each comprise a first lateral annular sub-portion L2' and L3' proximal to the equatorial plane XX, and a second lateral annular sub-portion L2'' and L3'' distal to the equatorial plane XX of the tire 1.

[0183] Preferably, the grooves 13 and 14 are formed in the first lateral annular sub-parts L2' and L3' of the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8 of the tire 1.

[0184] Preferably, the first lateral annular sub-parts L2' and L3' of the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8 are arranged adjacent to the central annular portion L1 on the axial side so as to define an interface 16 that separates the central annular portion L1 from the lateral annular portions L2 and L3 along the axial direction.

[0185] Within the framework of the present invention, the interface 16 also forms a separation interface along the axial direction between the first vulcanized elastomer material constituting the central annular portion L1 of the radially outer portion 11 and the second vulcanized elastomer material constituting the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8.

[0186] The intersection between the plane passing through the boundary surface 16 and the radially outer surface of the tread band 8 defines a pair of circumferential lines 17, 18 (see Figures 3 and 4) on both sides of the equatorial plane XX, which identify the proximal ends of the transverse annular portions L2, L3 of the radially outer portion 11 of the tread band 8 to the equatorial plane XX.

[0187] Preferably, the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8, and therefore the circumferential lines 17, 18, are positioned at a distance from the equatorial plane XX of the tire 1 that is at least 10% of the axial semi-extended portion L / 2 of the tread band 8, as defined above.

[0188] Preferably, the first lateral annular sub-parts L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 extend transversely along 40-65%, preferably 45-60%, of the axial semi-extended portion L / 2 of the tread band 8.

[0189] Preferably, the central annular portion L1 of the radially outer portion 11 is integrated with the radially inner portion 12 of the tread band 8, for example, by arranging adjacent rings of at least one continuous elongated element of the first vulcanized elastomer material in the circumferential direction.

[0190] Preferably, the lateral annular portions L2, L3 of the tread band 8 are also integrally formed, for example, by arranging adjacent rings of at least one continuous elongated element of the second vulcanized elastomer material described above in the circumferential direction.

[0191] Thus, as outlined above, in the radially outer portion 11 of the tread band 8, a pair of interface surfaces 16 between the first vulcanized elastomer material and the second vulcanized elastomer material are defined on both sides of the central annular portion L1 on both sides of the equatorial plane XX of the tire 1.

[0192] In the preferred embodiment shown in Figure 2, the interface 16 can converge from the inside to the outside of the tread band 8 toward the equatorial plane XX of the tire 1 and is oriented in a direction inclined with respect to the equatorial plane XX at an angle between 30° and 50°, preferably between 35° and 40°.

[0193] Preferably, the interface 16 is positioned symmetrically with respect to the equatorial plane XX of the tire 1. In this case, the aforementioned inclination angles of the interface 16 are considered to be measured in opposite directions from the equatorial plane XX, as schematically illustrated in Figure 2.

[0194] In this preferred configuration of the tread band 8, the radially inner portion 12 of the tread band 8 extends substantially along the entire axially extended portion of the belt structure 6.

[0195] Therefore, in this preferred configuration of the tread band 8, the radially inner portion 12 of the tread band 8 is radially sandwiched between the belt structure 6 and the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8.

[0196] Preferably, the grooves 13 and 14 define an overall void-to-rubber ratio of 4% or more and 8% or less, preferably 4% or more and 5% or less, in the tread band 8.

[0197] Preferably, the grooves 13 and 14 are the first lateral annular sub-parts L2' and L3' of the lateral annular parts L2 and L3 of the radially outer part 11 of the tread band 8, respectively, and define a void-to-rubber ratio of 0% or more and 30% or less, preferably 0% or more and 25% or less.

[0198] As outlined above, the aforementioned values ​​for the void-to-rubber ratio in each of the first lateral annular sub-sections L2' and L3' are considered to be calculated by dividing the radially outer portion 11 of the tread band 8 into annular sections having, for example, a 5 mm transverse extension, and then calculating the ratio values ​​within each annular section.

[0199] Figure 3 shows a graph illustrating the position of the circumferential line 18, defined by the interface 16 together with the radially outer surface of the tread band 8, as an example referring to one of the two axial semi-extended portions L / 2 of the tread band 8, and the trend of the void-to-rubber ratio of the tread band 8 in half of the front tire 1 according to a preferred embodiment described herein.

[0200] It can be understood that the aforementioned mirroring trend of the air gap-to-rubber ratio exists in the halves of the front tires 1, which are positioned on both sides with respect to the equatorial plane XX.

[0201] In Figure 3, the circumferential line 18 separates the central annular portion L1 formed from the first vulcanized elastomer material and the lateral annular portion L3 formed from the second vulcanized elastomer material along the axial direction.

[0202] Therefore, the X-axis, expressed in mm, represents the distance relative to the equatorial plane XX, and the Y-axis represents the air gap to rubber ratio.

[0203] The solid line represents the trend of the air-to-rubber ratio of the front tire 1 according to the illustrated preferred embodiment.

[0204] Preferably, the tire 1 has a void-to-rubber ratio that is variable along the axial extension, between a minimum value substantially equal to zero along the circumferential lines 17, 18 and a maximum value located in the first lateral annular sub-parts L2', L3' of the lateral annular parts L2, L3 of the radially outer portion 11 of the tread band 8.

[0205] More specifically, as better illustrated in Figure 3 with reference to one of the two halves of the front tire 1, the multiple grooves 13, 14 define an air-to-rubber ratio that increases with distance from the equatorial plane XX of the tire 1, starting from the circumferential lines 17, 18, along the axial semi-extension portion L / 2 of the tread band 8, in the first lateral annular sub-parts L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8, starting from the circumferential lines 17, 18.

[0206] Advantageously, the position of the interface 16 between the central annular portion L1 of the radially outer portion 11 of the tread band 8 and the first lateral annular sub-portions L2', L3' of the lateral annular portions L2, L3, where the grooves 13, 14 are located, allows for the acquisition of appropriate "mobility" characteristics of the solid portion defined in the tread band 8 between the grooves 13, 14.

[0207] These "mobility" characteristics of the solid portion are advantageously adapted to "heat" the second vulcanized elastomer material under the "low temperature" operating conditions of tire 1, resulting in a substantial improvement in performance under these operating conditions.

[0208] Preferably, as better illustrated in Figure 3, the grooves 13 and 14 are located axially outward of the first lateral annular sub-parts L2' and L3' of the lateral annular parts L2 and L3 of the radially outer portion 11 of the tread band 8, and in the first annular sector A adjacent to the central annular portion L1, they define an air-to-rubber ratio that increases as it moves away from the equatorial plane XX of the tire 1, starting from the circumferential lines 17 and 18 defined by the boundary surface 16 along the axial extension of the tread band 8.

[0209] Preferably, the first annular sector A starts from the circumferential lines 17, 18 and extends transversely along 5-25%, preferably 10-20%, of the axial half-extension L / 2 of the tread band 8.

[0210] Preferably, in the first annular sector A, the void-to-rubber ratio increases from a minimum value of about 0% at the circumferential lines 17 and 18 defined by the interface 16 to a maximum value that falls between 20% and 30% at the axial outer end A' of the first annular sector A.

[0211] Preferably, the axial outer end A' of the first annular sector A is positioned at a distance from the equatorial plane XX of the tire 1 that is at least 13% of the axial semi-extended portion L / 2 of the tread band 8.

[0212] More preferably, the axial outer end A' of the first annular sector A is located at a distance from the equatorial plane XX of the tire 1, which is included between 15% and 35% of the axial semi-extended portion L / 2 of the tread band 8.

[0213] Preferably, as better illustrated in Figure 3, the grooves 13 and 14 are located axially outward of the first lateral annular sub-parts L2' and L3' of the lateral annular parts L2 and L3 of the radially outer portion 11 of the tread band 8, and in the second annular sector B adjacent to the first annular sector A, they define a gap-to-rubber ratio that decreases as you move away from the equatorial plane XX of the tire 1, starting from the aforementioned first annular sector A, along the axial extension of the tread band 8.

[0214] Preferably, the second annular sector B extends transversely from the first annular sector A along 15-60%, more preferably 25-50%, of the axial semi-extended portion L / 2 of the tread band 8.

[0215] Preferably, in the second annular sector B, the void-to-rubber ratio decreases from a maximum value of approximately 25% at the axial outer end A' of the first annular sector A to a minimum value equal to approximately 0% at the axial outer end of the first lateral annular sub-parts L2' and L3' of the lateral annular parts L2 and L3 of the radially outer portion 11 of the tread band 8.

[0216] Preferably, the axial outer ends of the first lateral annular sub-parts L2', L3' of the lateral annular parts L2, L3 of the radially outer portion 11 of the tread band 8, which coincide with the axial outer end of the second annular sector B, are positioned at a distance from the equatorial plane XX of the tire 1 that is at least 55%, more preferably at least 60%, of the axial semi-extended portion L / 2 of the tread band 8.

[0217] Preferably, the second lateral annular sub-parts L2'', L3'' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 extend transversely along 10-55%, more preferably 20-45%, of the axial semi-extended portion L / 2 of the tread band 8 of the tire 1.

[0218] Preferably, the second lateral annular sub-parts L2'' and L3'' of the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8 are substantially groove-free.

[0219] The compound of the different parts of the tread band 8, like the compound of the other semi-finished parts forming the tire 1, contains at least one elastomerized polymer (a1).

[0220] Advantageously, such rubber compounds contain at least one α-olefin and have a specific formulation as described in more detail below.

[0221] According to one embodiment, the at least one elastomerized polymer (a1) can be selected from elastomerized polymers commonly used in elastomer compositions that are crosslinkable (vulcanizable) with sulfur, particularly suitable for tire manufacturing, i.e., from elastomerized polymers or copolymers having unsaturated chains with a glass transition temperature (Tg) typically lower than 20°C, preferably in the range of 0°C to -110°C. These polymers or copolymers may be of natural origin or, optionally, obtained by polymerization in solution, polymerization in emulsion, or gas-phase polymerization of one or more conjugated diolefins mixed with at least one comonomer selected from monovinylarenes and / or polar comonomers.

[0222] Polybutadiene (BR) and / or styrene-butadiene polymer (SBR), such as SSBR (styrene-butadiene elastomer from solution), are preferably used in combination with the tread rubber compound, either alone or in mixture.

[0223] Preferably, styrene-butadiene polymer (SBR) can be present in the rubber compound of the present invention in a variable amount of about 50 to 100 phr, more preferably 70 to 100 phr.

[0224] Advantageously, polybutadiene (BR) may not be present in the rubber compound of the present invention, particularly in the tread rubber compound, or it may be present in an amount of about 0 to 40 phr, more preferably about 10 to 30 phr.

[0225] Preferably, the styrene-butadiene polymer can be obtained by solution polymerization and generally contains about 10-40% by weight, preferably about 15-30% by weight, of styrene.

[0226] Preferably, the styrene-butadiene polymer can have a low molecular weight, with an average molecular weight Mn of less than 200,000 g / mol, preferably between 150,000 and 200,000 g / mol.

[0227] The elastomer material of different parts of the tread band 8 includes at least one reinforcing filler, which in the case of a vulcanized elastomer material is preferably a white filler such as silica, alumina, silicates, hydrotalcite, calcium carbonate, kaolin, titanium dioxide, and mixtures thereof, and in the case of a second vulcanized elastomer material is preferably and universally a carbon black filler.

[0228] Such reinforcing fillers are generally present in each vulcanized elastomer material in amounts between 40 phr and 130 phr.

[0229] Preferably, the first vulcanized elastomer material of the central annular portion L1 of the radially outer portion 11 of the tread band 8 is obtained by vulcanizing an elastomer compound comprising at least one elastomerized polymer 100 phr and a white reinforcing filler 70 to 110 phr, more preferably 80 to 100 phr.

[0230] In a preferred embodiment, the first vulcanized elastomer material of the central annular portion L1 of the radially outer portion 11 of the tread band 8 contains more than 70% by weight, more preferably 80% or more by weight, more preferably 85% or more by weight, more preferably 90% or more by weight, and more preferably 95% or more by weight of the "white" reinforcing filler as defined above, of the total weight of the reinforcing filler.

[0231] More preferably, such "white" reinforcing fillers are selected from silica, alumina, silicates, hydrotalcite, calcium carbonate, kaolin, titanium dioxide, and mixtures thereof.

[0232] More preferably, the "white" reinforcing filler is 50m 2 / g~500m 2 / g, more comfortably 70m 2 / g~200m 2The silica can be obtained by pyrolysis or sedimentation, and may contain a BET surface area (measured according to ISO standard 5794 / 1) between each g.

[0233] In this way, it is advantageously possible to achieve a rapid temperature rise of the tread band 8 of tire 1 and excellent grip on different road surface conditions.

[0234] Preferably, the second vulcanized elastomer material of the transverse annular portions L2 and L3 of the radially outer portion 11 of the tread band 8 is obtained by vulcanizing an elastomer compound containing at least one elastomerized polymer 100 phr and a carbon black reinforcing filler 40 to 100 phr, more preferably 50 to 90 phr, and even more preferably 60 to 80 phr.

[0235] In a preferred embodiment, the second elastomer material of the transverse annular portions L2 and L3 of the radially outer portion 11 of the tread band 8 contains carbon black in an amount greater than 75% by weight, more preferably 80% or more by weight, more preferably 85% or more by weight, more preferably 90% or more by weight, and more preferably 95% or more by weight of the total weight of the reinforcing filler.

[0236] Preferably, the carbon black is 20m 2 More than / g, preferably 50m 2 It is selected from those having a surface area greater than / g (determined by STSA - statistical thickness surface area according to ISO 18852:2005).

[0237] The carbon black can be, for example, N234, N326, N330, N375, or N550, N660 sold by Birla Group (India), or CRX 1391 from Cabot Corporation.

[0238] The reinforcing filler may include, for example, a mixture of carbon black and silica.

[0239] In this way, it is advantageously possible to optimize the value of the dynamic modulus E' of the second elastomer material as a function of the temperature value expected during use of tire 1.

[0240] The elastomer compositions described above and the elastomer compositions of other components of tire 1 can be vulcanized using known techniques, in particular using sulfur-based vulcanization systems commonly used for elastomer polymers. For this purpose, a sulfur-based vulcanizing agent is added to the elastomer composition along with a vulcanization accelerator after one or more thermomechanical treatment steps. In the final stage of this treatment, the temperature is generally kept below 140°C to avoid undesirable pre-crosslinking phenomena.

[0241] The most advantageous vulcanizing agents are sulfur or sulfur-containing molecules (sulfur donors), and accelerators and activators are known to those skilled in the art.

[0242] Particularly effective activators are zinc compounds, especially ZnO, ZnCO3, and zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms, for example, preferably zinc stearate formed in situ in the elastomer composition from ZnO and fatty acids, as well as BiO, PbO, Pb3O4, PbO2, or mixtures thereof.

[0243] Commonly used accelerators can be selected from dithiocarbamates, guanidine, thiourea, thiazoles, sulfenamides, thiuram, amines, xanthetes, or mixtures thereof.

[0244] The elastomer compositions used may include other additives that are generally selected based on the specific application for which each composition is intended.

[0245] For example, antioxidants, anti-aging agents, plasticizers, adhesives, anti-ozone agents, modified resins, fibers (aramid or naturally derived fibers), or mixtures thereof can be added to these elastomer compositions.

[0246] Table 1 below shows just an example of elastomer compositions that become the first and second vulcanized elastomer materials after vulcanization in a preferred embodiment of the front tire 1.

[0247] The amounts of various components of the elastomer composition are indicated by the phr as defined above.

[0248] [Table 1]

[0249] S-SBR: Styrene-butadiene copolymer polymerized in solution (phr as dry polymer, spread at 37.5 phr of TDAE oil per 100 phr of dry elastomer polymer) - TUFDENE E680 (Asahi Kasei) BR: Low-cis functionalized polybutadiene-YB03 (Asahi Kasei) CB:CRX(trademark)1391(Cabot) Silica: ULTRASIL(registered trademark) 7000 (Evonik) Liquid copolymer (grip enhancer): Low molecular weight butadiene / styrene liquid copolymer (4500 g / mol) - RICON® 100 (Cray Valley) Extension oil: TDAE (Orgkhim) Lubricant: Tris(2-ethylhexyl) phosphate (TOF) (Lanxess) Resin 1: Hydrocarbon resin - KRISTALEX (registered trademark) 5140LV (Flexys) Resin 2: Hydrocarbon resin - RHENOSIN (registered trademark) TT90 (Lanxess) Zinc salt: Zinc neodecanoate 50 (Rhein Chemie) Stearic acid: Stearic acid (Undesa) Zinc Oxide: RHENOGRAN(registered trademark) ZnO (Zincol Ossidi) SILAN (Evonik) Zinc stearate: ACID GRAS SARE DE ZINC (Eigemann & Veronelli) Wax: WAX (Repsol) Antioxidant: 2,2,4-trimethyl-1,1-dihydroquinoline-TMQ(Lanxess) Anti-ozone agent: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-SANTOFLEX(registered trademark)6PPD(Eastman) Sulfur: RHENOCURE (registered trademark) IS 90 P (Rhein Chemie) Crosslinking agent: Bifunctional 1,6-bis(NN'-dibenzylthiocarbamoyldithio)-hexane-VULCUREN(registered trademark)KA9188(Lanxess) Vulcanization accelerator 1: N-tert-butyl-benzothiazole sulfenamide-TBBS (Huatai Chemical) Vulcanization accelerator 2: Dibenzothiazole disulfide - RHENOGRAN(registered trademark) MBTS80 (Rhein Chemie) Vulcanization accelerator 3: Tetrabenzylthioram disulfide-TBZTD (Akrochem) Vulcanization retarder: N-(cyclohexylthio)phthalimide-PVI (Akrochem)

[0250] Preferably, the first vulcanized elastomer material of the central annular portion L1 of the radially outer portion 11 and the radially inner portion 12 of the tread band 8 has a dynamic modulus of elasticity E' measured at a frequency of 10 Hz and 23°C, with an elasticity ranging from 5.7 to 7.1 MPa, more preferably from 6.0 to 6.4 MPa.

[0251] Furthermore, the first vulcanized elastomer material of the central annular portion L1 of the radially outer portion 11 and the radially inner portion 12 of the tread band 8 has a tanδ measured at a frequency of 10 Hz and 23°C, which is between 0.37 and 0.47, preferably between 0.41 and 0.45.

[0252] According to the present invention, the ratio R1 between the dynamic modulus E' of the second vulcanized elastomer material of the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8, measured at a frequency of 10 Hz and 23°C, and the dynamic modulus E' of the first vulcanized elastomer material of the central annular portion L1 of the radially outer portion 11 and the radially inner portion 12 of the tread band 8, measured at a frequency of 10 Hz and 23°C, is between 0.6 and 1.2, preferably between 0.7 and 1.1.

[0253] Furthermore, the ratio R2 between the tanδ measured at a frequency of 10 Hz and 70°C for the second vulcanized elastomer material of the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8, and the tanδ measured at a frequency of 10 Hz and 23°C for the first vulcanized elastomer material of the central annular portion L1 of the radially outer portion 11 and the radially inner portion 12 of the tread band 8, is between 0.6 and 1.2, preferably between 0.7 and 1.1.

[0254] As outlined above, the applicant has experimentally observed that by controlling the aforementioned ratio R1 between stiffness characteristics correlated with the value of the dynamic elastic modulus E', and the aforementioned ratio R2 between hysteresis characteristics correlated with the value of tanδ, to a value close to 1, it is advantageous to have optimal dynamic and hysteresis behavior under "high temperature" usage conditions for the tire, while simultaneously improving drivability and grip performance on the road under "low temperature" usage conditions.

[0255] The front tire 1 may also have one or more of the above-mentioned desirable features to achieve corresponding advantageous technical effects.

[0256] Next, the present invention will be described by some examples, which are for illustrative purposes only and not for limiting purposes.

[0257] Properties of vulcanized elastomer compositions Table 2 below shows just examples of elastomer compositions that become the first and second vulcanized elastomer materials after vulcanization in a particularly preferred embodiment of the front tire 1.

[0258] The amounts of various components of the elastomer composition are shown in phr, and the components are as defined at the end of Table 1 above.

[0259] [Table 2]

[0260] Table 3 below shows the results of static and dynamic mechanical analysis performed on samples of the compositions used for the first vulcanized elastomer material in the central annular portion L1 and radially inner portion 12 of the radially outer portion 11, and for the second vulcanized elastomer material in the lateral annular portions L2 and L3 of the radially outer portion 11 of the tread band 8 of the front tire 1 according to the present invention, the formulations of which are shown in Table 2 above.

[0261] These analyses were performed under temperature and frequency conditions using the methods described above.

[0262] [Table 3]

[0263] CA1: Load at 100% elongation CA3: Load at 300% elongation

[0264] Table 4 below shows the ratios R1 and R2 between the dynamic mechanical properties of the elastic modulus E' and tanδ of various vulcanized elastomer materials, as far as is of interest for the purposes of the present invention.

[0265]

Table 4

[0266] From Table 4, it is clearly understood that the values of the ratios R1 and R2 close to 1 predict homogeneous behavior between the second vulcanized elastomer material and the first vulcanized elastomer material in both the "low temperature" and "high temperature" usage conditions.

[0267] In this way, as outlined above, such vulcanized elastomer materials, as will be illustrated in more detail below by reference to tests conducted outdoors on comparative tires and the tires according to the present invention, enable maintaining optimal drivability and grip performance usage conditions in the "high temperature" usage condition, while at the same time improving drivability and grip performance in the "low temperature" usage condition of the front tires.

[0268] Outdoor Tests of Tires The applicant selected a size 120 / 70ZR17 front-wheel super sports tire having a cross-sectional curvature ratio equal to approximately 0.42 as the basis for comparative running tests for the purpose of improving performance.

[0269] The tire according to the present invention had the "cap and base" configuration of the tread band described above with reference to FIG. 2. In such a tire, the compounds shown in Table 2 having the mechanical properties shown in Tables 3 and 4 were used to fabricate the tread band.

[0270] The performance of such a tire was compared with the performance of a comparative tire that was of a similar size and construction but differed only in the configuration and composition of the tread band.

[0271] In this case, the comparative tire for the front wheels was for a race track and was approved for use on ordinary roads and had the configuration of a single compound type tread band customary for this type of tire.

[0272] The tread band of the comparison tire was made of the materials shown in Table 5 below.

[0273]

Table 5

[0274] S-SBR1: Styrene-butadiene copolymer polymerized in solution (phr as dry polymer, extended with 37.5 phr of TDAE oil per 100 phr of dry elastomer polymer) - SBR1789 (Synthos)

[0275] S-SBR2: Styrene-butadiene copolymer polymerized in solution (phr as dry polymer, extended with 37.5 phr of TDAE oil per 100 phr of dry elastomer polymer) - HP755 (JSR) CB: CRX (trademark) 1391 (Cabot) Extending oil: TDAE (Nynas) Resin 1: Hydrocarbon resin - KRISTALEX (registered trademark) F85 (Flexys) Resin 2: Hydrocarbon resin - RASINA BM01 (SER) Stearic acid: Stearic acid (Wilmar) Zinc oxide: RHENOGRAN (registered trademark) ZnO (Zincol Ossidi) Antioxidant: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine - SANTOFLEX (registered trademark) 6PPD (Eastman) Sulfur: RHENOCURE (registered trademark) IS 90 P (Rhein Chemie) Vulcanization accelerator: N-tert-butyl-benzothiazole sulfenamide - TBBS80 (Rhein Chemie) Vulcanization retarder: N-(cyclohexylthio)phthalimide - PVI (Akrochem)

[0276] Various test sessions were conducted on a private racetrack, performing a series of maneuvers to test grip and handling in both dry and wet conditions. Driver ratings are the average of their performance across the various maneuvers.

[0277] The conditions for the dry ground tests were as follows: Tire pressure: 2.3 bar, track asphalt temperature: 45°C, ambient temperature: 30°C.

[0278] The conditions for the test on wet ground were as follows: Tire pressure: 2.5 bar, track asphalt temperature: 29°C, ambient temperature: 30°C.

[0279] The test was conducted using a BMW® S1000RR motorcycle, a "supersport" segment model.

[0280] Tables 6 and 7 below summarize the scores assigned by testers to various types of required performance for the tires being tested, in tests conducted on dry and wet surfaces, respectively.

[0281] In Tables 6 and 7, the performance of the comparison tire is identified by the symbol " / ", while the performance of the tire according to the present invention is indicated by the symbol "=" to show equal performance to the comparison tire, and by the symbol "+" to show improved performance compared to the comparison tire. A greater number of these symbols indicates a greater improvement in performance.

[0282] [Table 6]

[0283] [Table 7]

[0284] During the test, it was also found that the lap time on the test circuit was significantly shortened for the tire according to the present invention.

[0285] The results shown in Tables 6 and 7 demonstrate that the tire according to the present invention shows a much improved behavior with respect to both adhesion and handling, and also with respect to camber angles which are typically not reached by front tires on wet road surfaces, compared to already excellent comparison tires on wet ground.

[0286] The results shown in Tables 6 and 7 also demonstrate that the tire according to the present invention shows a behavior similar or even improved with respect to the performance on dry ground.

[0287] Various changes can be made to the detailed embodiments described, as long as one remains within the scope of protection of the present invention defined by the following claims.

Claims

1. A front tire (1) for a motorcycle, comprising an equatorial plane (X-X) and a tread band (8) having a fully axially extended portion (L), The aforementioned tread band (8) a) A radially outer portion (11) having an axially extended portion equal to the axially extended portion (L) of the tread band (8), a1) A central annular portion (L1) made of a first vulcanized elastomer material is positioned to straddle the equatorial plane (X-X) of the tire (1), a2) A radially outer portion (11) comprising a pair of lateral annular portions (L2, L3) arranged on both sides of the central annular portion (L1) with respect to the equatorial plane (X-X) of the tire (1), the pair of lateral annular portions (L2, L3) made of a second vulcanized elastomer material, b) A radially inner portion (12) of the tread band (8) that extends below the radially outer portion (11) of the tread band (8) along the entire axial extension of the radially outer portion (11), and which is made of the first vulcanized elastomer material, The ratio R1 of the dynamic modulus E' of the second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8), measured at a frequency of 10 Hz and 23°C, to the dynamic modulus E' of the first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread band (8), measured at a frequency of 10 Hz and 23°C, is between 0.6 and 1.

2. Front tire for motorcycle (1), wherein the ratio R2 of the tanδ of the second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8), measured at a frequency of 10 Hz and 70°C, to the tanδ of the first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread band (8), measured at a frequency of 10 Hz and 23°C, is between 0.6 and 1.

2.

2. The front tire (1) for a motorcycle according to claim 1, wherein the first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread band (8) has a dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C, with a pressure between 5.7 and 7.1 MPa.

3. The front tire (1) for a motorcycle according to claim 1 or 2, wherein the first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 23°C, with the tanδ being between 0.37 and 0.

47.

4. The front tire (1) for a motorcycle according to claim 1, wherein the second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) has a dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C, with a pressure between 5.2 and 6.5 MPa.

5. The front tire (1) for a motorcycle according to claim 1, wherein the second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 70°C, with the tanδ being between 0.34 and 0.

44.

6. The front tire (1) for a motorcycle according to claim 1, wherein the first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread band (8) is obtained by vulcanizing an elastomer material comprising at least one elastomerized polymer 100 phr and a white reinforcing filler 70 to 110 phr.

7. The front tire (1) for a motorcycle according to claim 1, wherein the second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) is obtained by vulcanizing an elastomer material comprising at least one elastomerized polymer 100 phr and a carbon black reinforcing filler 40 to 100 phr.

8. The front tire (1) for a motorcycle according to claim 1, wherein the central annular portion (L1) of the radially outer portion (11) of the tread band (8) extends transversely along 5 to 25% of the axially semi-extended portion (L / 2) of the tread band (8).

9. The front tire (1) for a motorcycle according to claim 1, wherein the ends (17, 18) of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8), which are proximal to the equatorial plane (X-X), are positioned at a distance from the equatorial plane (X-X) that is at least 10% of the axial semi-extended portion (L / 2) of the tread band (8).

10. The front tire (1) for a motorcycle according to claim 1, wherein each of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is arranged adjacent to the central annular portion (L1) on the axial side, such that it defines an interface (16) separating the central annular portion (L1) and the lateral annular portions (L2, L3) along the axial direction.

11. The front tire (1) for a motorcycle according to claim 1, wherein the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) extend transversely along 75 to 95% of the axially semi-extended portion (L / 2) of the tread band (8).

12. The front tire (1) for a motorcycle according to claim 1, wherein the central annular portion (L1) of the radially outer portion (11) of the tread band (8) substantially does not contain grooves.

13. The lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) each comprise a first lateral annular sub-portion (L2', L3') proximal to the equatorial plane (X-X) and a second lateral annular sub-portion (L2'', L3'') distal to the equatorial plane (X-X). The front tire (1) for a motorcycle according to claim 1, wherein the tire (1) comprises a plurality of grooves (13, 14) formed in the first lateral annular sub-parts (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8).

14. The front tire (1) for a motorcycle according to claim 13, wherein the first lateral annular sub-parts (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) extend transversely along 40-65% of the axially semi-extended portion (L / 2) of the tread band (8).

15. The front tire (1) for a motorcycle according to claim 13 or 14, wherein the plurality of grooves (13, 14) define an overall void-to-rubber ratio of 4% or more and 8% or less in the tread band (8).

16. The front tire (1) for a motorcycle according to claim 13, wherein the plurality of grooves (13, 14) define a gap-to-rubber ratio of 0% or more and 30% or less in each first lateral annular sub-part (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8).

17. Each of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is arranged adjacent to the central annular portion (L1) on the axial side, such that it defines an interface (16) separating the central annular portion (L1) and the lateral annular portions (L2, L3) along the axial direction, Front tire (1) for a motorcycle according to claim 16, wherein the plurality of grooves (13, 14) are located axially outward in the first annular sector (A) of the first lateral annular sub-parts (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8), and adjacent to the central annular portion (L1), and define an air gap to rubber ratio that increases as it moves away from the equatorial plane (X-X) of the tire (1) along the axial semi-extended portion (L / 2) of the tread band (8) from the boundary surface (16).

18. Front tire for motorcycle (1) according to claim 17, wherein the first annular sector (A) extends transversely from the ends (17, 18) of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) that are proximal to the equatorial plane (X-X), along 5-25% of the axial semi-extended portion (L / 2) of the tread band (8).

19. Front tire (1) for a motorcycle according to claim 18, wherein in the first annular sector (A), the air gap to rubber ratio increases from a minimum value of about 0% at the end (17, 18) of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) that is close to the equatorial plane (X-X), to a maximum value that falls between 20% and 30% at the axial outer end (A') of the first annular sector (A).

20. The front tire (1) for a motorcycle according to claim 19, wherein the axial outer end (A') of the first annular sector (A) is positioned at a distance from the equatorial plane (X-X) of the tire (1) that is at least 13% of the axial semi-extended portion (L / 2) of the tread band (8).

21. Front tire (1) for a motorcycle according to claim 17, wherein the plurality of grooves (13, 14) are located axially outward in the second annular sector (B) adjacent to the first annular sector (A) and along the axially extended portion (L) of the tread band (8), the first lateral annular sub-portions (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8), and define a gap-to-rubber ratio that decreases as the distance from the equatorial plane (X-X) of the tire (1) increases along the entire axial extension (L) of the tread band (8) from the first annular sector (A).

22. The motorcycle front tire (1) according to claim 21, wherein the second annular sector (B) extends transversely from the first annular sector (A) along 15-60% of the axial semi-extended portion (L / 2) of the tread band (8).

23. Front tire for motorcycle (1) according to claim 22, wherein in the second annular sector (B), the air gap to rubber ratio decreases from a maximum value of about 25% at the axial outer end (A') of the first annular sector (A) to a minimum value equal to about 0% at the axial outer end of the first lateral annular sub-parts (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8).

24. Front tire (1) for a motorcycle according to claim 23, wherein the axial outer end of the first lateral annular sub-part (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) is positioned at a distance from the equatorial plane (X-X) of the tire (1) that is at least 55% of the axial semi-extended portion (L / 2) of the tread band (8).

25. The front tire (1) for a motorcycle according to claim 13, wherein the second lateral annular sub-parts (L2'', L3'') of the lateral annular portion (L2, L3'') of the radially outer portion (11) of the tread band (8) extend transversely along 10 to 55% of the axially semi-extended portion (L / 2) of the tread band (8).

26. Front tire for motorcycle (1) according to claim 13, wherein the second lateral annular sub-parts (L2'', L3'') of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) substantially do not contain grooves.

27. The front tire (1) for a motorcycle according to claim 1, wherein the tire has a transverse curvature ratio of 0.35 or more and 0.50 or less.

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