Front tire of motorcycle

Abstract

The present application describes a front tyre (1) for a motorcycle wheel, comprising an equatorial plane (X-X) and a tread band (8) having an entire axial extension (L) and comprising a radially outer portion (11) and a radially inner portion (12) made of a first vulcanised elastomeric material, the radially outer portion comprising: a1) a central annular portion (L1), the central annular part is arranged across the equatorial plane (X-X) of the tyre (1) and is made of a first vulcanized elastomeric material; and a2) a pair of lateral annular portions (L2, L3) arranged on opposite sides of the central annular portion (L1) with respect to the equatorial plane (X-X) of the tyre (1) and made of a second vulcanized elastomeric material. In the tyre (1), the ratio R1 between the dynamic elastic modulus E'of the second vulcanized elastomeric material measured at a frequency of 10 Hz and 23 DEG C and the dynamic elastic modulus E 'of the first vulcanized elastomeric material measured at a frequency of 10 Hz and 23 DEG C is comprised between 0.6 and 1.2. In the tyre (1), the ratio R2 between the loss factor of the second vulcanized elastomeric material, measured at a frequency of 10 Hz and 70 DEG C, and the tandet of the first vulcanized elastomeric material, measured at a frequency of 10 Hz and 23 DEG C, is comprised between 0.6 and 1.2.

Description

TECHNICAL FIELD

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

[0002] In particular, the present invention relates to a motorcycle tire for the "super sport" and / or "hyper sport" segments having a large displacement (e.g., 600 cm 3 or 1000 cm 3 or greater) and / or high power (e.g., 200 hp or greater), such motorcycle tires also being used on race tracks. BACKGROUND OF THE INVENTION

[0003] For example, motorcycle tires are known from EP 2 662 226 A1 and WO 2019 / 082012. SUMMARY OF THE INVENTION

[0004] In recent years, there has been an observed trend in the market towards the introduction of high-power super sport or hyper sport motorcycles. Indeed, there are, for example, road motorcycles on the market with a displacement of 1000 cm 3 and greater and a power of 200 hp or even greater.

[0005] The applicant has noticed that there is an increasing demand for high-performance tires for sporty driving (e.g., achieved on a race track) as well as for year-round road use of motorcycles (especially in adverse weather conditions).

[0006] In this regard, the applicant has particularly observed a recent trend among users to combine the following in tires fitted to super sport motorcycles: drivability and performance under extreme handling and speed conditions on dry and / or hot surfaces (hereinafter also referred to as "hot" usage conditions), as well as drivability and road holding under wet or moist conditions and / or in cold weather or on non-optimal road surfaces (hereinafter also referred to as "cold" usage conditions), while at the same time maintaining the performance of the tire as constant as possible over time.

[0007] Meeting these conflicting requirements with a single pair of tires is a particularly challenging task, given that different types of actions are typically required for each of the above requirements, leading to solutions that are suitable for a particular problem but conflicting with other problems.

[0008] To improve drivability and performance on dry and / or hot ground as well as in wet or moist conditions and / or in cold weather or on non-optimal road surfaces, it is particularly necessary to ensure optimal adhesion to the ground under these different driving conditions.

[0009] To improve the grip of a tyre, so-called soft vulcanised elastomeric materials may be used to manufacture the tread band, which better adapt to the roughness of the road surface by mimicking the irregular profile of the road surface. These vulcanised elastomeric materials typically have the characteristics of a low elastic modulus and / or a high hysteresis.

[0010] However, the applicant has found that overly soft vulcanised elastomeric materials result in a decrease in the stability of the tyre when driving along a straight route and a reduction in the mileage of the tyre.

[0011] To overcome the above problems, tyres made of different vulcanised elastomeric materials have been proposed. Typically, the vulcanised elastomeric material at the shoulders is softer, while the vulcanised elastomeric material at the crown is less soft.

[0012] For example, a tyre configured in this way is described in EP 2 662 226.

[0013] However, with regard to this construction of the tread band, the applicant has observed that, under "cold" usage conditions, the drivability and performance of the tyre tend to decrease, especially in the case of road use on wet ground, severely impairing the performance of the tyre.

[0014] To attempt to meet the above conflicting requirements with a single pair of tyres, tyres have also been proposed that have a tread band made of different vulcanised elastomeric materials. Typically, vulcanised elastomeric materials with a higher carbon black filler content are used at the shoulders, while various vulcanised elastomeric materials with a higher white filler content are used at the crown and at the intermediate annular portion of the tread band.

[0015] In combination with an appropriate distribution and arrangement of the grooves of the tread band at the interfaces of the vulcanised elastomeric materials of different compositions, all things such as those described in the patent application WO2019 / 082012 in the name of the present applicant.

[0016] In the process of continuously improving motorcycle tyres (especially front tyres), the applicant has set itself a dual task: to maintain the drivability and performance of the front tyre at an excellent level under "hot" usage conditions, while improving the drivability and grip performance of the front tyre under the aforementioned "cold" usage conditions (both on dry and wet ground).

[0017] The applicant has found that by adopting a so-called "crown base" tread band construction and by using vulcanised elastomeric materials that have appropriate dynamic mechanical properties under both the "cold" and "hot" usage conditions of the tyre, it is possible to achieve this dual task.

[0018] In particular, the applicant has found that, for this purpose, the following provisions need to be taken simultaneously:

[0019] i) The structure of the radially outer part of the tread band of the tire includes a central annular part arranged across the equatorial plane of the tire and a pair of lateral annular parts arranged on the axially opposite sides of the central annular part;

[0020] ii) A harder first vulcanized elastomeric material is used in the radially inner part of the tread band and the central annular part of the radially outer part of the tread band, while a softer second vulcanized elastomeric material is used in the lateral annular parts of the radially outer part of the tread band; and

[0021] iii) Materials having specific mechanical stiffness characteristics related to the dynamic elastic modulus E' under the "cold" usage conditions of the tire and specific hysteretic mechanical characteristics related to tan delta under the "hot" usage conditions of the tire are used as the first vulcanized elastomeric material and the second vulcanized elastomeric material.

[0022] In this regard, the applicant has actually found that, in order to achieve the above dual tasks, it is necessary to evaluate the dynamic mechanical properties of the vulcanized elastomeric materials used to manufacture different parts of the tread band in a differentiated manner under specific stress and temperature conditions related to the actual usage conditions of each elastomeric material. Each elastomeric material is subjected to different types of stress and temperature during the use of the front tire depending on its position in the tread band.

[0023] Regarding the "cold" usage of the tire, the applicant has particularly found that the dynamic mechanical property predicting the behavior of the front tire under such usage conditions is the dynamic elastic modulus E' measured at a frequency of 10 Hz and a temperature of 23 °C for all elastomeric materials constituting the tread band.

[0024] Conversely, regarding the "hot" usage of the front tire, the applicant has found that the dynamic mechanical property predicting the behavior of the tire under such usage conditions is tan delta measured under the following conditions respectively:

[0025] - At a frequency of 10 Hz and a temperature of 23 °C, for the first vulcanized elastomeric material of the radially inner part and the central annular part of the radially outer part of the tread band, tan delta is measured; and

[0026] - At a frequency of 10 Hz and a temperature of 70 °C, for the second vulcanized elastomeric material of the lateral annular part of the radially outer part of the tread band, tan delta is measured.

[0027] Therefore, the applicant has unexpectedly found that by keeping the following dynamic mechanical properties close to a value of 1, it is possible to simultaneously achieve the desired retention of driving performance and grip performance of the front tire under the above "hot" usage conditions and the improvement of driving performance and grip performance under the above "cold" usage conditions:

[0028] - The ratio between the "cold" dynamic elastic modulus E' of the second vulcanized elastomeric material and the first vulcanized elastomeric material; and

[0029] - The ratio between the "hot" tandelta of the second vulcanized elastomeric material and the first vulcanized elastomeric material.

[0030] That is, it is achieved by keeping the "cold" dynamic elastic modulus E' and the "hot" tandelta of these two vulcanized elastomeric materials at similar values to each other.

[0031] Therefore, the present invention relates to a front motorcycle tire, the front motorcycle tire comprising an equatorial plane and a tread band having an overall axially extending portion,

[0032] wherein the tread band comprises:

[0033] a) A radially outer portion, the radially outer portion comprising:

[0034] a1) A central annular portion, the central annular portion being arranged across the equatorial plane of the tire and made of a first vulcanized elastomeric material, and

[0035] a2) A pair of lateral annular portions, the pair of lateral annular portions being arranged on opposite sides of the central annular portion with respect to the equatorial plane of the tire, the pair of lateral annular portions being made of a second vulcanized elastomeric material;

[0036] b) A radially inner portion, the radially inner portion being below the radially outer portion of the tread band and extending along the entire axially extending portion of the tread band, the radially inner portion being made of the first vulcanized elastomeric material;

[0037] wherein the ratio R1 between the dynamic elastic modulus E' of the second vulcanized elastomeric 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 elastic modulus E' of the first vulcanized elastomeric material of the central annular portion and the radially inner portion of the radially outer portion of the tread band measured at a frequency of 10 Hz and 23 °C is included between 0.6 and 1.2; and

[0038] wherein the ratio R2 between the tandelta (loss factor) of the second vulcanized elastomeric material of the lateral annular portion of the radially outer portion of the tread band measured at a frequency of 10 Hz and 70 °C and the tandelta of the first vulcanized elastomeric material of the central annular portion and the radially inner portion of the radially outer portion of the tread band measured at a frequency of 10 Hz and 23 °C is included between 0.6 and 1.2.

[0039] Basically, in the front tire according to the present invention, the following characteristics seem to be effectively integrated:

[0040] i) The ground "mimicking" characteristics of the front tyre, which are related to the hysteresis characteristics under "hot" usage conditions; and

[0041] ii) The uniformity characteristics of the response of the front tyre to the stresses applied under "cold" usage conditions.

[0042] The Applicant has found that the combination of these characteristics allows a motorcycle front tyre (especially a motorcycle front tyre in the "super sport" and / or "hyper sport" market segments) to maintain its drivability and grip performance over time on dry and / or hot ground conditions, while improving its drivability and grip performance under "cold" usage conditions, in wet or damp conditions and / or in cold weather or on non-optimal road surface conditions.

[0043] Without wishing to be bound by any explanatory theory, the Applicant believes that under "hot" usage conditions, the front tyre as defined above has a substantially uniform hysteresis behaviour in the shoulder area (i.e., the area most stressed under such usage conditions).

[0044] This result may seem surprising since the use of a relatively "hard" vulcanised elastomeric material in the radially inner part of the tread band not only seems unsuitable for providing adequate performance under such usage conditions, but may even lead (conversely) to a sharp decline in the performance of the front tyre.

[0045] On the contrary, the Applicant has found that the substantially uniform dynamic and hysteresis behaviour of the tread band under the "hot" usage conditions of the front tyre allows the "mimicking" characteristics of the tyre to be maintained, thus avoiding performance degradation and premature wear phenomena.

[0046] Conversely, and again without wishing to be bound by any explanatory theory, the Applicant believes that under "cold" usage conditions, the front tyre as defined above has a substantially uniform dynamic behaviour overall in the tread band under such usage conditions.

[0047] The Applicant has particularly observed that under the "cold" usage conditions of the front tyre, the vulcanised elastomeric material constituting the tread band has a very homogeneous behaviour, which is considered to be essentially related to the homogeneity of the "cold" dynamic elastic modulus E' values of the second vulcanised elastomeric material and the first vulcanised elastomeric material.

[0048] Advantageously, therefore, the front tyre according to the present invention not only allows the best drivability and grip performance to be maintained under dry and / or hot ground usage conditions (typical track usage conditions), but is also capable of achieving improved drivability and grip performance under "cold" usage conditions (typical road usage conditions).

[0049] From a practical point of view, this translates into an advantage that is particularly appreciated by users, namely that it is not necessarily necessary to change the front tyre when switching from track usage to road usage, and vice versa.

[0050] In this specification and the following claims, unless otherwise indicated, all numerical entities representing quantities, parameters, percentages, etc. shall be understood to be prefaced by the term "about" in all instances. Additionally, except for those specifically noted hereinafter, the ranges of all numerical entities include all possible combinations of the maximum and minimum values and all possible intermediate ranges.

[0051] Unless otherwise indicated, the ranges of all numerical entities also include the maximum and minimum values.

[0052] For the purposes of the present invention, the following definitions apply.

[0053] The term "phr" (abbreviation for parts per hundred rubber) represents the number of parts by weight of a given component of an elastomeric composite per 100 parts by weight of an elastomeric polymer, the elastomeric polymer being considered exclusive of any possible plasticizer extender oil.

[0054] The terms "elastomeric material", "rubber", "elastomeric polymer", or "elastomer" are used to denote a material comprising a vulcanizable natural or synthetic polymer and reinforcing fillers, where such a material, after vulcanization at room temperature, can withstand deformation caused by a force and is capable of rapidly and strongly returning to substantially its original shape and dimensions (as defined in accordance with ASTM standard D1566 - 11, Standard Terminology Relating to Rubber).

[0055] The term "diene polymer" is used to denote a polymer or copolymer obtained by the polymerization of one or more different monomers, at least one of which is a conjugated diene (conjugated diolefin).

[0056] The term "composite" or "elastomeric composite" is used to denote a mixture obtained by mixing and possibly heating at least one elastomeric polymer and at least one additive typically used in the preparation of tire composites.

[0057] The term "vulcanizable composite" or "vulcanizable elastomeric composite" is used to denote an elastomeric mixture ready for vulcanization, which can be obtained by incorporating all additives, including vulcanization additives, into the elastomeric composite.

[0058] The term "vulcanized elastomeric material" is used to denote a material obtained by vulcanizing a vulcanizable elastomeric composite.

[0059] The term "vulcanization" is used to denote the cross - linking reaction in natural or synthetic rubber caused by a cross - linking agent, typically a sulfur - based one.

[0060] The term "vulcanizing agent" is used to denote a compound capable of transforming natural or synthetic rubber into an elastic and robust material by forming a three-dimensional network of intermolecular and intramolecular bonds. Typical vulcanizing agents are sulfur-based compounds such as elemental sulfur, polymeric sulfur, sulfur donor agents such as bis[(trialkoxysilyl)propyl] polysulfides, thiurams, dithiomorpholines, and caprolactam disulfides.

[0061] The term "vulcanization accelerator" is used to denote a compound capable of reducing the duration of the vulcanization process and / or reducing the operating temperature, such as TBBS, sulfenamides, thiazoles, dithiophosphates, dithiocarbamates, guanidines, and sulfur donors such as thiurams.

[0062] The term "vulcanization activator" is used to denote a compound capable of further promoting vulcanization so that vulcanization occurs in a shorter time and possibly at a lower temperature. An example of an activator is the stearic acid-zinc oxide system.

[0063] The term "vulcanization retarder" is used to denote a compound capable of delaying the start of the vulcanization reaction and / or inhibiting unwanted side reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0064] The term "reinforcing filler" is used to denote a reinforcing material typically used in the art to improve the mechanical properties of a tire, preferably selected from carbon black and "white fillers".

[0065] The term "white filler" is used to denote traditional reinforcing materials used in the art, which are selected from traditional silica and silicates such as silica sand (preferably amorphous diatomaceous earth) precipitated with strong acid, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicates, kaolin, silicate fibers, layered silicates such as sepiolite, palygorskite (also known as attapulgite), montmorillonite, halloysite, and the like, which are optionally modified and / or derivatized by acid treatment, and mixtures thereof. Typically, white fillers have surface hydroxyl groups.

[0066] The term "motorcycle front tire" is used to denote a tire having a high curvature ratio (usually equal to or greater than 0.35) and capable of achieving a high camber angle when traveling along a curve.

[0067] The term "curvature ratio" is used to denote the ratio between the distance (also represented by an "arrow") included in the cross-section of the tire between the radially highest point of the tread band and the maximum width of the radial section of the tire and the said maximum width of the tire.

[0068] The term "axial extension" of the tread band or a part thereof is used to denote the extension in the cross-section intercepted in the plane of the tire containing the axis of rotation of the tire of the radially outermost contour of the tread band or a part thereof.

[0069] The term "semi-axial extension" of a tread pattern, tread band or a part thereof is used to denote the extension from the equatorial plane towards the axially outermost end of the tire in a section taken in a plane containing the axis of rotation of the tire of the radially outermost contour of the tread band or a part thereof.

[0070] The term "equatorial plane" of a tire is used to denote a plane perpendicular to the axis of rotation of the tire and bisecting the tire symmetrically.

[0071] The term "width" is used to denote a dimension measured in a direction perpendicular to the equatorial plane.

[0072] The term "tread pattern" is used to denote the presentation of all points (including sipes) of the tread band in a plane perpendicular to the equatorial plane of the tire and tangent to the maximum diameter of the tire. The tread pattern is defined by a plurality of solid portions separated by sipes and may include grooves.

[0073] The terms "radial" and "axial" and the expressions "radially in / out" and "axially in / out" are used by reference to a direction substantially parallel to the equatorial plane of the tire and a direction substantially perpendicular to the equatorial plane of the tire, respectively, i.e., by reference to a direction substantially perpendicular to the axis of rotation of the tire and a direction substantially parallel to the axis of rotation of the tire, respectively.

[0074] The terms "circumferential" and "circumferentially" are used by reference to the circumferential extension direction of the tire, i.e., by reference to the rolling direction of the tire, which corresponds to a direction lying in a plane coinciding with or substantially parallel to the equatorial plane of the tire.

[0075] The term "circumferential extension" of a tire, tread band or a part thereof is used to denote the planar extension of the radially outermost surface of the tire, tread band or a part thereof in a plane tangent to the tire.

[0076] The expressions "axially in" and "axially out" denote positions closer to and farther from the equatorial plane, respectively, relative to a reference element.

[0077] The term "radial carcass structure" is used to denote a carcass structure including a plurality of reinforcing cords, each reinforcing cord being oriented in a substantially axial direction in the crown part of the tire. Such reinforcing cords may be incorporated into a single carcass ply or may be incorporated into several (preferably two) carcass plies radially superposed on one another.

[0078] The term "substantially axial direction" is used to denote a direction in which the angle of inclination relative to the equatorial plane of the tire is included between 60° and 90°.

[0079] The term "substantially circumferential direction" is used to denote a direction in which the angle of orientation relative to the equatorial plane of the tire is included between 0° and 20°.

[0080] The term "static mechanical properties" of the tread compound is used to denote the stress-strain properties under tension of the vulcanized thermoplastic rubber measured on a sample of the compound vulcanized at 170 °C for 10 minutes at a predetermined temperature according to the UNI 6065:2001 standard.

[0081] The term "dynamic mechanical properties" of the tread compound is used to denote the mechanical properties measured in tension-compression mode using an Instron model 1341 dynamic device as described herein.

[0082] A test piece of the crosslinked material in the form of a cylinder (length = 25 mm; diameter = 18 mm) (170 °C, 15 minutes) is preloaded under compression until the longitudinal deformation reaches 25% of the initial length and is maintained at a predetermined temperature (e.g., 23 °C and 70 °C) throughout the test. After waiting for 2 minutes, the test piece is mechanically preconditioned 125 times at 10 Hz with a deformation amplitude of 7.5% of the length under the preload, and then the test piece is subjected to a dynamic sinusoidal stress with an amplitude of ±3.5% of the length under the preload and a predetermined frequency of e.g., 10 Hz. The dynamic mechanical properties are expressed as the values of the dynamic elastic modulus (E') and tandelta (loss factor). The tandelta value is calculated as the ratio between the viscous dynamic modulus (E") and the elastic dynamic modulus (E').

[0083] The term "total void rubber ratio" is used to denote the ratio between the total surface of the grooves of a specific annular portion (which may be the entire tread band) of the tread band and the total surface of the entire tread band.

[0084] The term "annular portion" or "annular segment" is used to denote a portion or segment of the tread band that extends circumferentially along the entire tread band and has a predetermined axial extension.

[0085] Unless otherwise specified, the distance of the annular tread portion or annular tread segment from the equatorial plane or the distance between the annular portions or annular segments is axially evaluated with reference to the central plane parallel to the equatorial plane of the one or more portions.

[0086] The term "void rubber ratio of the annular portion" or "void rubber ratio of the annular segment", or collectively the "void rubber ratio", is used to denote the ratio between the total surface of the grooves of the annular portion or annular segment and the total surface of the annular portion itself or annular segment itself.

[0087] "Substantially groove-free" with respect to a portion of the tread band of a tire is used to denote that in the portion of the tread band under consideration, the "void rubber ratio" as defined above is very close to or substantially equal to zero, e.g., its value is less than 0.2%.

[0088] The term "pitch" of a tire is used to denote a set of grooves and solid portions arranged to form part of a tread pattern, the tread pattern being substantially the same and repeating uninterruptedly along the circumferential extension of the tread band. Along the circumferential extension of the tread band, the pitches may have different circumferential lengths and may be circumferentially offset from one another on opposite sides of the equatorial plane of the tire.

[0089] The expression "module" relating to the tread band (in particular relating to the tread pattern) is used to denote a tread pattern portion that repeats identically in sequence along the entire circumferential extension of the tread band itself. While maintaining the same tread pattern configuration, these modules may still have different circumferential lengths and / or have corresponding portions that are circumferentially offset on opposite sides of the equatorial plane of the tire and along the circumferential extension of the tire itself.

[0090] In the second case, the tire includes "pitches" that are circumferentially offset from one another on opposite sides of the equatorial plane.

[0091] The present invention may have one or more of the following preferred features in one or more of the above aspects, and, if desired, these preferred features may be combined with one another according to application requirements.

[0092] Preferably, the ratio R1 between the dynamic elastic modulus E' of the second vulcanized elastomeric material of the lateral annular portion of the radially outer part of the tread band measured at a frequency of 10 Hz and 23 °C and the dynamic elastic modulus E' of the first vulcanized elastomeric material of the central annular portion and the radially inner part of the radially outer part of the tread band measured at a frequency of 10 Hz and 23 °C is included between 0.7 and 1.1.

[0093] In this way, it is possible to advantageously make the tread band have optimal behavior homogeneity characteristics under "cold" use conditions of a front tire, where driving performance and road holding performance are significantly improved under these use conditions.

[0094] Preferably, the ratio R2 between the tandelta of the second vulcanized elastomeric material of the lateral annular portion of the radially outer part of the tread band measured at a frequency of 10 Hz and 70 °C and the tandelta of the first vulcanized elastomeric material of the central annular portion and the radially inner part of the radially outer part of the tread band measured at a frequency of 10 Hz and 23 °C is included between 0.7 and 1.1.

[0095] In this way, it is possible to advantageously make the tread band have optimal ground "mimicking" characteristics under "hot" use conditions of a front tire, while maintaining or further improving its drivability and road holding performance under these use conditions.

[0096] In fact, from the perspective of its "thermal" deformation ability, the shoulder region of the tread band of the front tire is formed of a vulcanized elastomeric material that is substantially "homogeneous" from the perspective of its road behavior.

[0097] Preferably, the dynamic elastic modulus E' of the first vulcanized elastomeric material of the central annular portion and the radially inner portion of the radially outer portion of the tread band measured at a frequency of 10 Hz and 23 °C is included between 5.7 MPa and 7.1 MPa, more preferably included between 6.0 MPa and 6.4 MPa.

[0098] In this way, it is possible to advantageously make the radially inner portion of the tread band have sufficient stiffness and support characteristics under the "cold" use conditions of the front tire.

[0099] Preferably, the tandelta of the first vulcanized elastomeric material of the central annular portion and the radially inner portion of the radially outer portion of the tread band measured at a frequency of 10 Hz and 23 °C is included between 0.37 and 0.47, preferably included between 0.41 and 0.45.

[0100] Advantageously, this preferred feature helps to optimize and substantially maintain or improve the drivability and performance of the front tire on dry and / or hot surfaces under the "hot" use conditions of the front tire during cornering driving.

[0101] Preferably, the dynamic elastic modulus E' of the second vulcanized elastomeric 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 is included between 5.2 MPa and 6.5 MPa, more preferably included between 5.6 MPa and 6.0 MPa.

[0102] Advantageously, this preferred feature helps to achieve the best homogeneity of the tread band of the front tire to improve the drivability and performance of the tire under "cold" use conditions.

[0103] Preferably, the tandelta of the second vulcanized elastomeric material of the lateral annular portion of the radially outer portion of the tread band measured at a frequency of 10 Hz and 70 °C is included between 0.34 MPa and 0.44 MPa, more preferably included between 0.38 MPa and 0.40 MPa.

[0104] Advantageously, this preferred feature helps to achieve the best "mimicking" characteristics of the tread band on the ground under the "hot" use conditions of the front tire, while maintaining or further improving the drivability and road holding performance under these use conditions.

[0105] Preferably, the central annular portion of the radially outer part and the first vulcanized elastomeric material of the radially inner part of the tread band are obtained by vulcanizing an elastomeric material comprising 100 phr of at least one elastomeric diene polymer and 70 phr to 110 phr (more preferably 80 phr to 100 phr) of a white reinforcing filler.

[0106] Preferably, the white reinforcing filler comprises an inorganic material, the amount of which, based on the total weight of the reinforcing filler, is equal to or greater than 80%, more preferably equal to or greater than 85%, more preferably equal to or greater than 90%, more preferably equal to or greater than 95%, and the inorganic material is selected from silica, alumina, silicate, hydroaluminate, calcium carbonate, kaolin, titanium dioxide and mixtures thereof.

[0107] Advantageously, this preferred feature contributes to achieving optimal wet grip characteristics under "cold" operating conditions of the front tire.

[0108] Preferably, the second vulcanized elastomeric material of the lateral annular portion of the radially outer part of the tread band is obtained by vulcanizing an elastomeric material comprising 100 phr of at least one elastomeric diene polymer and 40 phr to 100 phr (more preferably 50 phr to 90 phr, even more preferably 60 phr to 80 phr) of a carbon black reinforcing filler.

[0109] Preferably, the reinforcing filler comprises carbon black, the amount of which, based on the total weight of the reinforcing filler, is equal to or greater than 75%, preferably equal to or greater than 80%, more preferably equal to or greater than 85%, more preferably equal to or greater than 90%, more preferably equal to or greater than 95%.

[0110] Advantageously, this preferred feature contributes to achieving optimal grip characteristics under "hot" operating conditions of the front tire.

[0111] Preferably, the central annular portion of the radially outer part of the tread band extends transversely by 5% - 25% of the semi-axial extension of the tread band, preferably by 10% - 20% of the semi-axial extension of the tread band.

[0112] In this way, it may be advantageous to have optimal stiffness and road holding characteristics under "cold" operating conditions of the front tire.

[0113] Preferably, the end portion of the lateral annular portion of the radially outer part of the tread band close to the equatorial plane is arranged at a distance from the equatorial plane which is at least 10% of the semi-axial extension of the tread band itself.

[0114] In this way, it may be advantageous for the front tire to achieve optimal drivability and grip performance within a wide range of camber angles both on dry surfaces and on wet or moist surfaces.

[0115] In a preferred embodiment, each of the lateral annular portions of the radially outer part of the tread band is axially disposed outside and adjacent to the central annular portion to define an interface that separates the central annular portion and the lateral annular portion in the axial direction.

[0116] In this way, it is possible to advantageously and properly manage the transition in the axial direction between the first vulcanized elastomeric material and the second vulcanized elastomeric material in the tread band to achieve the desired dynamic mechanical characteristics and behavioral homogeneity of the front tire.

[0117] In a preferred embodiment, the aforementioned interface can converge from the inner side to the outer side of the tread band towards the equatorial plane of the tire.

[0118] In this case, the aforementioned interface can be preferably inclined at an angle between 30° and 50°, more preferably at an angle between 35° and 40°, with respect to the equatorial plane of the tire.

[0119] In this way, it may be advantageous to achieve a gradual transition in the axial direction between the first vulcanized elastomeric material and the second vulcanized elastomeric material in the tread band, thereby achieving the best dynamic mechanical characteristics and behavioral homogeneity of the front tire.

[0120] In an alternative preferred embodiment, the aforementioned interface can be parallel to the equatorial plane of the tire, or further, diverge from the equatorial plane from the inner side to the outer side of the tread band.

[0121] In this case, the aforementioned interface can be inclined at an angle preferably between 120° and 140°, more preferably between 125° and 130°, with respect to the equatorial plane of the tire.

[0122] Preferably, the lateral annular portions of the radially outer part of the tread band extend transversely along 75%-95% of the semi-axial extension of the tread band, more preferably along 80%-90% of the semi-axial extension of the tread band.

[0123] In this way, it is possible to advantageously optimize the drivability and grip performance of the front tire within a wide range of camber angles on both dry surfaces and wet or moist surfaces.

[0124] In a particularly preferred embodiment, the central annular portion of the radially outer part of the tread band is substantially free of grooves.

[0125] In this way, it may be advantageous to optimize the drivability and grip performance of the front tire under wet or moist conditions due to the adhesion ability of the first vulcanized elastomeric material of the central annular portion of the radially outer part of the tread band.

[0126] Preferably, the lateral annular portions of the radially outer portion of the tread band each include 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.

[0127] Preferably, the tire includes a plurality of grooves formed in the first lateral annular sub-portion of the lateral annular portion of the radially outer portion of the tread band.

[0128] The applicant has found through experiments that due to these features, there is a significant synergy between the construction of the tread pattern in the grooved portion and the stiffness mechanical properties of the tread band having the "crown base" structure defined above, thereby achieving optimal drivability and performance of the tire on wet and / or cold surfaces.

[0129] Preferably, the first lateral annular sub-portion of the aforementioned lateral annular portion of the radially outer portion of the tread band extends transversely along 40% to 65% of the semi-axial extension of the tread band, more preferably along 45% to 60% of the semi-axial extension of the tread band.

[0130] In this way, it may be advantageous that, since the lateral annular portion (especially its first lateral annular sub-portion) of the radially outer portion of the tread band can drain the water present below the tire-ground contact area in the most commonly used tread band area during the "cold" use conditions of the front tire, the drivability and grip performance of the front tire on wet or moist surfaces are optimized.

[0131] Preferably, the total void rubber ratio defined by the aforementioned plurality of grooves in the tread band is greater than or equal to 4% and less than or equal to 8%, more preferably greater than or equal to 4% and less than or equal to 5%.

[0132] In this way, it may be advantageously given sufficient stiffness to the tread band without restricting its drainage capacity.

[0133] Preferably, the void rubber ratio defined by the aforementioned plurality of grooves in each first lateral annular sub-portion of the lateral annular portion of the radially outer portion of the tread band is greater than or equal to 0% and less than or equal to 30%, more preferably greater than or equal to 0% and less than or equal to 25%.

[0134] In the present disclosure, the value of the void rubber ratio is considered to be calculated by dividing the radially outer portion of the tread band into annular regions having a predetermined transverse extension amount (e.g., 5 mm) and by calculating the ratio value within each annular region.

[0135] In this way, it may be advantageously achieved the best compromise between the drivability and grip performance of the front tire under "cold" use conditions, on wet or moist conditions, and the drivability and grip performance under "hot" use conditions.

[0136] In a preferred embodiment, the plurality of grooves define a void rubber ratio in each first lateral annular sub - portion of the lateral annular portion of the radially outer portion of the tread band in a first annular segment disposed axially outside and adjacent to the central annular portion, and the void rubber ratio increases along the semi - axial extension of the tread band and from the aforementioned interface as it moves away from the equatorial plane of the tire.

[0137] Preferably, the aforementioned first annular segment extends transversely along 5% - 25% of the semi - axial extension of the tread band, more preferably along 10% - 20% of the semi - axial extension of the tread band, from the end of the lateral annular portion of the radially outer portion of the tread band proximal to the equatorial plane (in other words, from the circumferential line defined by the intersection of the plane passing through the interface and the radially outer surface of the tread band), and the proximal end separates the central annular portion and the lateral annular portion of the radially outer portion of the tread band in the axial direction.

[0138] Preferably, in the aforementioned first annular segment, the void rubber ratio increases from a minimum value of about 0% at the end of the lateral annular portion of the radially outer portion of the tread band proximal to the equatorial plane to a maximum value between 20% and 30% at the axially outer end of the first annular segment.

[0139] Preferably, the axially outer end of the first annular segment is disposed at a distance from the equatorial plane of the tire that is at least 13% of the semi - axial extension of the tread band.

[0140] More preferably, the axially outer end of the first annular segment is disposed at a distance from the equatorial plane of the tire that is between 15% and 35% of the semi - axial extension of the tread band.

[0141] In this way, it may be advantageous to optimize the drivability and grip performance of the front tire in wet or moist conditions due to the synergistic cooperation between the structure of the tread pattern and the mechanical hysteresis characteristics of the second vulcanized elastomeric material of the lateral annular portion of the radially outer portion of the tread band.

[0142] In particular, under the "cold" operating conditions of the front tire, the lateral annular portion of the radially outer portion of the tread band can effectively drain the water present below the tire - ground contact area in the most commonly used tread - band areas during straight - line driving and often when cornering with a relatively low camber angle, while the mechanical hysteresis characteristics of the tread band allow for a homogeneous response to the stresses to which the tire is subjected under these operating conditions.

[0143] In a preferred embodiment, the plurality of grooves define a void rubber ratio in each first lateral annular sub - portion of the lateral annular portion of the radially outer portion of the tread band, in a second annular segment that is axially outside and adjacent to the first annular segment. The void rubber ratio extends along the axial extension of the tread band and decreases as it moves away from the equatorial plane of the tire starting from the aforementioned first annular segment.

[0144] Preferably, the second annular segment extends transversely from the first annular segment by 15% - 60% of the semi - axial extension of the tread band, more preferably by 25% - 50% of the semi - axial extension of the tread band.

[0145] Preferably, in the second annular segment, the void rubber ratio decreases from a maximum value of about 25% at the axially outer end of the first annular segment to a minimum value of about 0% at the axially outer end of the first lateral annular sub - portion of the lateral annular portion of the radially outer portion of the tread band.

[0146] Advantageously, in this preferred embodiment of the invention, the value of the void rubber ratio decreases gradually as it moves away from the equatorial plane of the tire, which allows for the full utilization of the hysteresis characteristics of the second vulcanized elastomer in the case of handling conditions and high camber conditions that can be achieved during a race / on a race track under hot conditions.

[0147] In other words, in this preferred embodiment of the invention, there is an effective synergistic interaction between the characteristics of the vulcanized elastomer material of the radially outer portion and the characteristics of the tread pattern.

[0148] Preferably, the axially outer end of the first lateral annular sub - portion of the lateral annular portion of the radially outer portion of the tread band, which coincides with the axially outer end of the second annular segment, is arranged at a distance from the equatorial plane X - X of the tire, and the distance is at least 55% of the semi - axial extension of the tread band, more preferably at least 60% of the semi - axial extension of the tread band.

[0149] In this way, it is possible to advantageously optimize the drivability and grip performance of the tire when driving along a bend under "hot" usage conditions and thus in the absence of a wet or moist surface, in which case driving is often carried out with a relatively high camber.

[0150] Preferably, the second lateral annular sub - portion of the lateral annular portion of the radially outer portion of the tread band extends transversely by 10% - 55% of the semi - axial extension of the tread band of the tire, more preferably by 20% - 45% of the semi - axial extension of the tread band.

[0151] In a particularly preferred embodiment, each second lateral annular sub - portion of the aforementioned lateral annular portion of the radially outer portion of the tread band is substantially free of grooves.

[0152] In this way, it is possible to advantageously optimize the drivability and the grip performance of the tyre during driving along a bend in "hot" use conditions and thus in the absence of a wet or moist surface, in which case driving is often carried out with a relatively high camber angle.

[0153] Preferably, the lateral curvature ratio of the front tyre for a motorcycle according to the invention is equal to or greater than 0.35 and equal to or less than 0.50, more preferably equal to or greater than 0.39 and equal to or less than 0.45, even more preferably equal to or greater than 0.40 and equal to or less than 0.44. Description of the drawings

[0154] With reference to the accompanying drawings, other features and advantages of the present invention will become more apparent from the following description of some preferred embodiments of the invention given for illustrative and non - limiting purposes.

[0155] These figures are schematic and are not drawn to scale.

[0156] In the drawings:

[0157] Figure 1 A perspective view of a front tyre according to a preferred embodiment of the invention is shown;

[0158] Figure 2 is Figure 1 an enlarged schematic cross - section of the front tyre;

[0159] Figure 3 is a graph showing the trend of the void - rubber ratio along the semi - axial extension of the front tyre, which also indicates the position of the circumferential line separating the central annular part and the lateral annular part of the radially outer part of the tread band in the axial direction; and Figure 1

[0160] Figure 4 Figure 1 is a schematic plan view of a part of the tread band of the front tyre. Detailed description of the invention

[0161] In the figures, the reference numeral 1 generally denotes a front tyre for a motorcycle wheel according to a preferred embodiment of the invention. This concerns a tyre which is preferably intended for the rear wheel of a supersport motorcycle with a large displacement (e.g. 600 cc) in the "supersport" and "hyper - sport" market segments.

[0162] An equatorial plane X - X and a rotation axis (not shown) are defined in the tyre 1. A circumferential direction (indicated by an arrow F oriented in the rotation direction of the tyre 1 in Figure 1 and Figure 4 is also defined) and an axial direction (in Figure 2represented by an axis r perpendicular to the equatorial plane X-X).

[0163] The tire 1 includes a carcass structure 2 formed by at least one carcass ply 3, the carcass ply including a plurality of reinforcing elements (cords). In Figure 1 the illustrated embodiment, there are two carcass plies 3.

[0164] The carcass structure 2 is typically coated on its inner wall with a sealing layer or a so-called "liner", which is mainly composed of an airtight elastomeric material layer and is adapted to ensure the airtight seal of the tire itself after inflation.

[0165] The reinforcing elements included in the carcass ply 3 preferably include fabric cords made of a fiber material.

[0166] The fiber material for manufacturing the cords can be made of fibers of natural or synthetic origin, the fibers being selected from rayon, lyocell, polyester (e.g., PEN, PET, PVA), aramids (e.g., such as aramids), and these fibers can be individual or mixed. More specifically, the fiber material for manufacturing the cords is preferably selected from polyester, rayon, lyocell, aramids or a mixed material formed by two or more of the above materials.

[0167] The reinforcing elements included in at least one carcass ply 3 are preferably arranged in the radial direction, i.e., arranged according to an angle included between 70° and 110° (more preferably between 80° and 100°) with respect to the circumferential direction.

[0168] At least one carcass ply 3 is formed according to a generally annular configuration and is joined to at least one annular reinforcing structure by its opposite circumferential edges 3a.

[0169] In particular, the opposite lateral edges 3a of at least one carcass ply 3 can be turned up around the annular reinforcing structure, each said annular reinforcing structure including one or more metal annular bead cores 4 and a tapered elastomeric filler 5, the tapered elastomeric filler occupying the space defined between the carcass ply 3 and the corresponding turned-up lateral edge 3a of the carcass ply 3.

[0170] The tire area including the bead core 4 and the filler 5 forms a so-called bead 9, which is intended to anchor the tire 1 to a corresponding mounting rim (not shown).

[0171] In an embodiment not shown, at least one carcass layer 3 is made by bringing together a plurality of strips of elastomeric material reinforced by the aforementioned cords and its opposite lateral edges are associated without turning up with a specific annular reinforcing structure provided with two annular inserts. A filler made of elastomeric material can be arranged at an axially outer position relative to the first annular insert. On the other hand, a second annular insert can be arranged at an axially outer position relative to the end of the carcass layer. Finally, at an axially outer position relative to the second annular insert (and not necessarily in contact with it), another filler may be arranged, which ends the manufacture of the annular reinforcing structure.

[0172] Circumferentially applied to the carcass structure 2 at a radially external position is a belt structure 6 comprising at least one belt layer 6a typically formed of rubberized cords.

[0173] Preferably, the belt layer 6a is made of cords arranged substantially parallel and side by side to form a plurality of turns. Such turns are oriented substantially according to a circumferential direction (typically with an angle between 0° and 5°), this direction being generally referred to as "zero degrees" with reference to its laying arrangement relative to the circumferential direction of the tire.

[0174] Preferably, the belt layer 6a, often called "zero degree", may comprise axially adjacent windings of a single cord or a rubberized fabric belt comprising axially adjacent cords.

[0175] The cords of the belt layer 6a are textile cords or metal cords. Preferably, the cords are metal cords made of steel wires with a high carbon content, ie made of steel wires with a carbon content of at least 0.6%-0.7%.

[0176] Preferably, such metal cords have a high elongation (HE).

[0177] In order to improve the adhesion between the belt structure 6 and the carcass structure 2, an adhesion layer 7 made of elastomeric material (not shown) may be interposed between the two structures.

[0178] In an embodiment not shown, the belt structure 6 may consist of at least two radially superposed layers arranged so that the cords of a first belt layer are oriented obliquely with respect to the circumferential direction of the tire, while the cords of the second layer also have an oblique orientation but cross substantially symmetrically with respect to the cords of the first layer.

[0179] Circumferentially superimposed on the belt structure 6 is a tread band 8 on which, after a moulding operation carried out while the tyre is being vulcanised, typically longitudinal and transverse grooves are formed, these grooves being arranged so as to define the desired tread pattern.

[0180] Figure 1 , Figure 2 andFigure 4 A tread pattern is shown by way of non - limiting example, the tread pattern including a plurality of grooves 13, 14 which are arranged in different ways on opposite sides of the equatorial plane X - X of the tire 1 and meet the requirements of the void - rubber ratio variation trend and groove distribution of the front tire 1 according to a preferred embodiment of the present invention.

[0181] As Figure 4 Better shown, the tread pattern includes a module 15 which repeats along the circumferential extension direction of the tire 1.

[0182] In Figure 4 The preferred embodiment of the front tire 1 shown, the module 15 includes 2 pitches P which are offset circumferentially from each other on opposite sides of the equatorial plane X - X of the tire 1.

[0183] In the case where the tire is intended to be mounted on the front wheel of a motorcycle (such as an object of the present invention), the above - mentioned module 15 repeats along the circumferential extension of the tire 1 at least 10 times. Preferably it repeats at least 12 times, for example 14 times.

[0184] Preferably, the tread pattern includes a series of circumferential first grooves 13 which are substantially L - shaped and preferably have a main length portion that tapers along the preferred rolling direction F of the tire 1.

[0185] Preferably, the tread pattern includes a series of circumferential second grooves 14 which are circumferentially interposed between the first grooves 13 and preferably taper along a direction opposite to the preferred rolling direction F of the tire 1.

[0186] Preferably, both the first grooves 13 and the second grooves 14 are inclined with respect to the equatorial plane X - X of the tire 1.

[0187] For simplicity, Figure 2 the first grooves 13 and the second grooves 14 are not shown in

[0188] The tire 1 may include a pair of sidewalls 10 which are laterally applied to the carcass structure 2 on opposite sides.

[0189] The tire 1 has a section height H measured in the equatorial plane X - X between the top of the tread band 8 and the assembly diameter passing through the bead of the tire 1 (identified by the reference line r).

[0190] The tire 1 also has a maximum width C in cross-section, which is defined by the distance between the axially opposite ends E of the profile of the tread band 8, and the tire 1 also has a curvature ratio, which is defined as the ratio of the distance f (measured in the equatorial plane of the tire 1) by which the top of the tread band 8 is spaced from the line passing through the ends E of the tread band 8 itself to the aforementioned maximum width C. The axially opposite ends E of the tread band 8 may be formed by corners.

[0191] In particular, the tire 1 has a cross-section characterized by a high curvature ratio, preferably with a transverse curvature ratio f / C equal to or greater than 0.35 and equal to or less than 0.50, more preferably equal to or greater than 0.39 and equal to or less than 0.45, and even more preferably equal to or greater than 0.40 and equal to or less than 0.44.

[0192] In a preferred embodiment, the front motorcycle tire 1 of the present invention is intended to be mounted on a front wheel with a chord length dimension substantially comprised between 100 mm and 130 mm.

[0193] Preferably, the distance f between the radially outer point of the tread band 8 of the tire 1 and the line passing through the axially opposite ends E of the tread band 8 of the tire 1 itself is substantially comprised between 47 mm and 55 mm.

[0194] Preferably, the total height / chord length ratio H / C is approximately between 0.60 and 0.70.

[0195] In a preferred embodiment, when the tire 1 has sidewalls 10 of appreciable height, the tire 1 allows for better performance, for example, with the value of the sidewall height ratio (H−f) / H equal to or greater than 0.3, and more preferably equal to or greater than 0.35.

[0196] According to the present invention, the tread band 8 is a so-called "crown-based (crown and base)" type tread band and is made of two different vulcanized elastomeric materials having the above characteristics.

[0197] In the preferred embodiment shown in the figures, the tread band 8 has an overall axial extension L and comprises:

[0198] a) a radially outer portion 11, said radially outer portion comprising:

[0199] a1) a central annular portion L1, said central annular portion being arranged across the equatorial plane X-X of the tire 1, and

[0200] a2) a pair of lateral annular portions L2, L3, said pair of lateral annular portions being arranged on opposite sides of the central annular portion L1 with respect to the equatorial plane X-X of the tire 1.

[0201] As described above, the central annular portion L1 is made of the aforementioned first vulcanized elastomeric material, while the lateral annular portions L2, L3 of the tread band 8 are made of the aforementioned second vulcanized elastomeric material.

[0202] In the preferred embodiment shown in the drawings, the tread band 8 includes a radially inner portion 12 that is below the radially outer portion 11 of the tread band 8 and extends along the entire axial extension of the tread band.

[0203] As described above, the radially inner portion 12 of the tread band 8 is made of the aforementioned first vulcanized elastomeric material.

[0204] Preferably, the central annular portion L1 of the tread band 8 has an axial extension L1 that extends transversely along 5% - 25% of the semi-axial extension L / 2 of the tread band 8, and more preferably along 10% - 20% of the semi-axial extension of the tread band 8.

[0205] Preferably, the lateral annular portions L2, L3 of the tread band 8 have corresponding axial extensions that extend transversely along 75% - 95% of the semi-axial extension L / 2 of the tread band 8, and more preferably along 80% - 90% of the semi-axial extension of the tread band 8.

[0206] Preferably and as Figure 4 better shown, each of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 includes a first lateral annular sub-portion L2', L3' that is proximal to the equatorial plane X-X of the tire 1 and a second lateral annular sub-portion L2", L3" that is distal to the equatorial plane X-X of the tire 1.

[0207] Preferably, the grooves 13, 14 are formed in the first lateral annular sub-portions L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 of the tire 1.

[0208] Preferably, each of the first lateral annular sub-portions L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 is arranged axially outside the central annular portion L1 and adjacent to the central annular portion to define an interface 16 that separates the central annular portion L1 from the lateral annular portions L2, L3 in the axial direction.

[0209] Within the framework of the present invention, the interface 16 also constitutes a separation interface between the first vulcanized elastomeric material and the second vulcanized elastomeric material in the axial direction, the first vulcanized elastomeric material constituting the central annular portion L1 of the radially outer portion 11 of the tread band 8, and the second vulcanized elastomeric material constituting the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8.

[0210] The intersection line between the plane passing through the interface 16 and the radial outer surface of the tread band 8 defines a pair of circumferential lines 17, 18 on the opposite side parts of the equatorial plane X-X (see Figure 3 and Figure 4 ), and this pair of circumferential lines identify the ends of the lateral annular parts L2, L3 of the radial outer part 11 of the tread band 8 that are proximal to the equatorial plane X-X.

[0211] Preferably, the lateral annular parts L2, L3 of the radial outer part 11 of the tread band 8 and thus the circumferential lines 17, 18 are arranged at a certain distance from the equatorial plane X-X of the tire 1 (as described above), and this distance is at least 10% of the semi-axial extension L / 2 of the tread band 8.

[0212] Preferably, the first lateral annular sub-parts L2', L3' of the lateral annular parts L2, L3 of the radial outer part 11 of the tread band 8 extend transversely along 40%-65% of the semi-axial extension L / 2 of the tread band 8, preferably along 45%-60% of the semi-axial extension of the tread band.

[0213] Preferably, the central annular part L1 of the radial outer part 11 is integrally formed with the radial inner part 12 of the tread band 8, for example, by laying a continuous circumferential coil of at least one continuous elongated element of the aforementioned first vulcanized elastomeric material.

[0214] Preferably, the lateral annular parts L2, L3 of the tread band 8 are also formed as one piece, for example, by laying a continuous circumferential coil of at least one continuous elongated element of the aforementioned second vulcanized elastomeric material.

[0215] In this way and as described above, a pair of interfaces 16 between the first vulcanized elastomeric material and the second vulcanized elastomeric material are defined in the radial outer part 11 of the tread band 8 and are located on the opposite side parts of the equatorial plane X-X of the tire 1 and the central annular part L1.

[0216] In Figure 2 the preferred embodiment shown, the interface 16 can converge from the inner side to the outer side of the tread band 8 towards the equatorial plane X-X of the tire 1 and be oriented at an inclination angle with respect to the inclination direction of the equatorial plane X-X, and this inclination angle is included between 30° and 50°, preferably between 35° and 40°.

[0217] Preferably, the interface 16 is symmetrically arranged with respect to the equatorial plane X-X of the tire 1. In this case, the above inclination angle of the interface 16 is considered to be measured along the opposite direction from the equatorial plane X-X, as Figure 2 schematically shown.

[0218] In this preferred configuration of the tread band 8, the radially inner portion 12 of the tread band 8 extends substantially along the entire axial extension of the belt structure 6.

[0219] Thus, in this preferred configuration of the tread band 8, the radially inner portion 12 of the tread band 8 is interposed in the radial direction between the belt structure 6 and the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8.

[0220] Preferably, the total void rubber ratio defined by the grooves 13, 14 in the tread band 8 is greater than or equal to 4% and less than or equal to 8%, preferably greater than or equal to 4% and less than or equal to 5%.

[0221] Preferably, the void rubber ratio defined by the grooves 13, 14 in each first lateral annular sub-portion L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 is greater than or equal to 0% and less than or equal to 30%, preferably greater than or equal to 0% and less than or equal to 25%.

[0222] As described above, the value of the void rubber ratio in each of the first lateral annular sub-portions L2', L3' is considered to be calculated by dividing the radially outer portion 11 of the tread band 8 into annular regions having a transverse extension of, for example, 5 mm and by calculating the ratio values within each annular region.

[0223] Figure 3 A graph is shown for one of the two half-axial extensions L / 2 of the tread band 8, which graph shows the position of the circumferential line 18 defined by the interface 16 and the radially outer surface of the tread band 8 and the trend of the void rubber ratio of the tread band 8 in the half of the front tire 1 according to the preferred embodiment described herein.

[0224] It should be understood that in the half of the front tire 1 arranged on the opposite sides with respect to the equatorial plane X-X, there is a mirror image trend of the aforementioned void rubber ratio.

[0225] In Figure 3 the circumferential line 18 separates the central annular portion L1 formed of the first vulcanized elastomeric material from the lateral annular portion L3 formed of the second vulcanized elastomeric material in the axial direction.

[0226] Thus, the X-axis represents the distance (in mm) from the equatorial plane X-X, and the Y-axis represents the void rubber ratio.

[0227] The solid line represents the trend of the void rubber ratio of the front tire 1 according to the shown preferred embodiment.

[0228] Preferably, the void rubber ratio of the tire 1 can vary between a minimum value that is substantially equal to zero at the circumferential lines 17, 18 along the axial extension and a maximum value in the first lateral annular sub - portions L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8.

[0229] More particularly and as Figure 3 better shown in, for one of the two half - portions of the front tire 1, the grooves 13, 14 define a void rubber ratio in each of the first lateral annular sub - portions L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8, and the void rubber ratio increases along the semi - axial extension L / 2 of the tread band 8 and away from the equatorial plane X - X of the tire 1 starting from the circumferential lines 17, 18.

[0230] Advantageously, the position of the interface 16 between the central annular portion L1 and each of the first lateral annular sub - portions L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 (where the grooves 13, 14 are located) allows to obtain appropriate "mobility" characteristics of the solid portions defined in the tread band 8 between the grooves 13, 14.

[0231] The "mobility" characteristics of these solid portions are advantageously suitable for "heating" the second vulcanized elastomeric material under "cold" use conditions of the tire 1 and having significantly improved performance under these use conditions.

[0232] Preferably and as Figure 3 better shown, the grooves 13, 14 define a void rubber ratio in a first annular segment A that is axially outside and adjacent to the central annular portion L1 in each of the first lateral annular sub - portions L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8, and the void rubber ratio increases along the axial extension of the tread band 8 and away from the equatorial plane X - X of the tire 1 starting from the circumferential lines 17, 18 defined by the interface 16.

[0233] Preferably, the first annular segment A extends transversely from the circumferential lines 17, 18 along 5% - 25% of the semi - axial extension L / 2 of the tread band 8, preferably along 10% - 20% of the semi - axial extension L / 2 of the tread band.

[0234] Preferably, in the first annular segment A, the void rubber ratio increases from a minimum value of about 0% at the circumferential lines 17, 18 defined by the interface 16 to a maximum value comprised between 20% and 30% at the axially outer end A' of the first annular segment A.

[0235] Preferably, the axially outer end A' of the first annular segment A is arranged at a distance from the equatorial plane X-X of the tire 1 which is at least 13% of the semi-axial extension L / 2 of the tread band 8.

[0236] More preferably, the axially outer end A' of the first annular segment A is arranged at a distance from the equatorial plane X-X of the tire 1 which is comprised between 15% and 35% of the semi-axial extension L / 2 of the tread band 8.

[0237] Preferably and as Figure 3 better shown, the grooves 13, 14 define in each first lateral annular sub-part L2', L3' of the lateral annular parts L2, L3 of the radially outer part 11 of the tread band 8 a void rubber ratio in the second annular segment B which is axially outside the first annular segment A and adjacent to the first annular segment, and which decreases along the axial extension of the tread band 8 and starting from said first annular segment A as it moves away from the equatorial plane X-X of the tire 1.

[0238] Preferably, the second annular segment B extends transversely from the first annular segment A by 15% - 60% of the semi-axial extension L / 2 of the tread band 8, more preferably by 25% - 50% of the semi-axial extension of the tread band.

[0239] Preferably, in the second annular segment B, the void rubber ratio decreases from a maximum value of about 25% at the axially outer end A' of the first annular segment A to a minimum value of about 0% at the axially outer ends of the first lateral annular sub-parts L2', L3' of the lateral annular parts L2, L3 of the radially outer part 11 of the tread band 8.

[0240] Preferably, the axially outer ends of the first lateral annular sub-parts L2', L3' of the lateral annular parts L2, L3 of the radially outer part 11 of the tread band 8 which coincide with the axially outer end of the second annular segment B are arranged at a distance from the equatorial plane X-X of the tire 1 which is at least 55% of the semi-axial extension L / 2 of the tread band 8, more preferably at least 60% of the semi-axial extension of the tread band.

[0241] Preferably, the second lateral annular sub-parts L2", L3" of the lateral annular parts L2, L3 of the radially outer part 11 of the tread band 8 extend transversely by 10% - 55% of the semi-axial extension L / 2 of the tread band 8 of the tire 1, more preferably by 20% - 45% of the semi-axial extension of the tread band.

[0242] Preferably, each second lateral annular sub-part L2", L3" of the lateral annular parts L2, L3 of the radially outer part 11 of the tread band 8 is substantially free of grooves.

[0243] The composite for different parts of the tread band 8 and other semi-finished products forming the tire 1 comprises at least one elastomeric diene polymer (a1).

[0244] Advantageously, such a rubber composite comprises at least one α-olefin and has a specific formulation, as will be described in more detail below.

[0245] According to one embodiment, the at least one elastomeric diene polymer (a1) may be selected, for example, from elastomeric diene polymers commonly used in elastomeric compositions capable of being crosslinked (vulcanized) with sulfur, which are particularly suitable for the production of tires, i.e., from elastomeric polymers or copolymers having unsaturated chains, the glass transition temperature (Tg) of which is generally below 20°C, preferably in the range of 0°C and -110°C. These polymers or copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas-phase polymerization of one or more conjugated dienes, optionally mixed with at least one comonomer selected from monovinylaromatics and / or polar comonomers.

[0246] For the tread rubber composite, polybutadiene (BR) and / or styrene-butadiene polymers (SBR), alone or in a mixture, such as SSBR (styrene-butadiene elastomer from solution), are preferably used.

[0247] Preferably, the styrene-butadiene polymer (SBR) may be present in the rubber composite of the present invention in variable amounts in the range of about 50 phr to 100 phr (more preferably in the range of 70 phr to 100 phr).

[0248] Advantageously, polybutadiene (BR) may be absent or may be included in the rubber composite of the present invention, particularly in the tread rubber composite, in an amount of about 0 phr to 40 phr, more preferably about 10 phr to 30 phr.

[0249] Preferably, the styrene-butadiene polymer may be obtained by solution polymerization and generally comprises about 10% to 40% by weight (preferably about 15% to 30%) of styrene.

[0250] Preferably, the styrene-butadiene polymer may have a low molecular weight, with an average molecular weight Mn below 200,000 g / mol, preferably comprised between 150,000 g / mol and 200,000 g / mol.

[0251] The elastomeric material of the different parts of the tread band 8 includes at least one reinforcing filler, which is preferably a white filler such as silica, alumina, silicate, hydrotalcite, calcium carbonate, kaolin, titanium dioxide and mixtures thereof for the vulcanized elastomeric material, while for the second vulcanized elastomeric material, the filler is preferably and generally a carbon black filler.

[0252] The content of such reinforcing filler in the corresponding vulcanized elastomeric material is generally included between 40 phr and 130 phr.

[0253] Preferably, the first vulcanized elastomeric material of the central annular portion L1 of the radially outer portion 11 of the tread band 8 is obtained by vulcanizing an elastomeric composite comprising 100 phr of at least one elastomeric diene polymer and 70 phr to 110 phr (more preferably 80 phr to 100 phr) of a white reinforcing filler.

[0254] In a preferred embodiment, the first vulcanized elastomeric material of the central annular portion L1 of the radially outer portion 11 of the tread band 8 includes the "white" reinforcing filler as defined above, in an amount by weight greater than 70% of the total weight of the reinforcing filler, more preferably equal to or greater than 80%, more preferably equal to or greater than 85%, more preferably equal to or greater than 90%, more preferably equal to or greater than 95%.

[0255] More preferably, such "white" reinforcing filler is selected from silica, alumina, silicate, hydrotalcite, calcium carbonate, kaolin, titanium dioxide and mixtures thereof.

[0256] Even more preferably, the "white" reinforcing filler can be fumed silica or precipitated silica, the BET surface area of which (measured according to ISO standard 5794 / 1) is included between 50 m 2 / g and 500 m 2 / g, more preferably between 70 m 2 / g and 200 m 2 / g.

[0257] In this way, it is possible to advantageously achieve a rapid temperature rise of the tread band 11 of the tire 1 and excellent grip under different road surface conditions.

[0258] Preferably, the second vulcanized elastomeric material of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 is obtained by vulcanizing an elastomeric composite comprising 100 phr of at least one elastomeric diene polymer and 40 phr to 100 phr (more preferably 50 phr to 90 phr, even more preferably 60 phr to 80 phr) of a carbon black reinforcing filler.

[0259] In a preferred embodiment, the second elastomeric material of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 comprises carbon black, the amount of which is greater than 75% by weight of the total weight of the reinforcing fillers, more preferably equal to or greater than 80%, more preferably equal to or greater than 85%, more preferably equal to or greater than 90%, more preferably equal to or greater than 95%.

[0260] Preferably, the carbon black is selected from carbon blacks having a surface area of not less than 20 m 2 / g (preferably greater than 50 m 2 / g) (determined by STSA - statistical thickness surface area according to ISO18852:2005).

[0261] The carbon black can be, for example, N234, N326, N330, N375 or N550, N660 sold by Birla Group (India) or CRX 1391 sold by Cabot Corporation.

[0262] The reinforcing fillers can include a mixture, for example, a mixture of carbon black and silica.

[0263] In this way, it is possible to advantageously optimize the value of the dynamic elastic modulus E’ of the second elastomeric material based on the expected temperature value during the use of the tire 1.

[0264] The elastomeric compositions described earlier and the elastomeric compositions of the other components of the tire 1 can be vulcanized according to known techniques, in particular using a sulfur - based vulcanization system commonly used for elastomeric polymers. For this purpose, in the elastomeric composition, after one or more thermo - mechanical treatment steps, a sulfur - based vulcanizing agent is admixed with a vulcanization accelerator. In the last step of the treatment, the temperature is generally maintained below 140 °C to avoid any undesired pre - crosslinking phenomenon.

[0265] The most advantageously used vulcanizing agent is sulfur or a sulfur - containing molecule (sulfur donor), which has accelerators and activators known to those skilled in the art.

[0266] Particularly effective activators are: zinc - based compounds, in particular ZnO, ZnCO3, zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms (e.g., zinc stearate), which are preferably formed in situ from ZnO and fatty acids in the elastomeric composition; and also BiO, PbO, Pb3O4, PbO2 or mixtures thereof.

[0267] Commonly used accelerators can be selected from: dithiocarbamates, guanidines, thioureas, thiazoles, sulfonamides, thiurams, amines, xanthates or mixtures thereof.

[0268] The elastomeric composition used may include other additives, which are generally selected according to the specific use intended for each composition.

[0269] For example, the following additives may be added to the elastomeric composition: antioxidants, anti-aging agents, plasticizers, adhesives, anti-ozone agents, modified resins, fibers (aramid or fibers of natural origin) or mixtures thereof.

[0270] In Table 1 below, examples of elastomeric compositions are given for illustrative purposes only, which are made into a first vulcanized elastomeric material and a second vulcanized elastomeric material after vulcanization in a preferred embodiment of the front tire 1.

[0271] The amounts of the various components in the elastomeric composition are provided in phr as defined above.

[0272] Table 1

[0273]

[0274]

[0275] * phr of dry polymer without extender oil

[0276] S-SBR: Solution-polymerized styrene-butadiene copolymer (phr given on dry polymer, 37.5 phr of TDAE oil added per 100 phr of dry elastomeric polymer) - TUFDENE E680 (Asahi Kasei)

[0277] BR: Functionalized low-cis polybutadiene - YB03 (Asahi Kasei)

[0278] CB: CRX TM 1391 (Cabot)

[0279] Silica: (Evonik)

[0280] Liquid copolymer (grip enhancer): Low molecular weight butadiene / styrene liquid copolymer (4500 g / mol) - (Cray Valley)

[0281] Extender oil: TDAE (Orgkhim)

[0282] Lubricant: Tris(2-ethylhexyl) phosphate (TOF) (Lanxess)

[0283] Resin 1: Hydrocarbon resin - (Flexys)

[0284] Resin 2: Hydrocarbon resin - 90 (Lanxess)

[0285] Zinc salt: Zinc neodecanoate 50 (Rhein Chemie)

[0286] Stearic acid: Stearic acid (Undesa)

[0287] Zinc oxide: (Zincol Ossidi)

[0288] Silane: SILAN (Evonik)

[0289] Zinc stearate: ACID GRAS SARE DE ZINC (Eigemann&Veronelli)

[0290] Wax: WAX (Repsol)

[0291] Antioxidant: 2,2,4 - Trimethyl - 1,1 - dihydroquinoline - TMQ (Lanxess)

[0292] Antiozonant: N - (1,3 - dimethylbutyl) - N’ - phenyl - p - phenylenediamine - (Eastman)

[0293] Sulfur: 90P (Rhein Chemie)

[0294] Cross - linker: Bifunctional 1,6 - bis(NN’ - dibenzylthiocarbamoyldithio) - hexane - 9188 (Lanxess)

[0295] Vulcanization accelerator 1: N - tert - butylbenzothiazole sulfenamide - TBBS (Huatai Chemicals)

[0296] Vulcanization accelerator 2: Dibenzothiazole disulfide - 80 (RheinChemie)

[0297] Vulcanization accelerator 3: Tetrabenzylthiuram disulfide - TBZTD (Akrochem)

[0298] Vulcanization retarder: N - (cyclohexylthio)phthalimide - PVI (Akrochem)

[0299] Preferably, the central annular portion L1 of the radially outer portion 11 and the first vulcanized elastomeric material of the radially inner portion 12 of the tread band 8 have a dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C and included between 5.7 MPa and 7.1 MPa, more preferably included between 6.0 MPa and 6.4 MPa.

[0300] Furthermore, the tandelta measured at a frequency of 10 Hz and 23°C of the central annular portion L1 of the radially outer portion 11 and the first vulcanized elastomeric material of the radially inner portion 12 of the tread band 8 is included between 0.37 and 0.47, preferably included between 0.41 and 0.45.

[0301] According to the present invention, the ratio R1 between the dynamic elastic modulus E' of the second vulcanized elastomeric material of the lateral annular portions L2, 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 elastic modulus E' of the first vulcanized elastomeric 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 included between 0.6 and 1.2, preferably included between 0.7 and 1.1.

[0302] Moreover, the ratio R2 between the tandelta of the second vulcanized elastomeric material of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 measured at a frequency of 10 Hz and 70°C and the tandelta of the first vulcanized elastomeric 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 included between 0.6 and 1.2, preferably included between 0.7 and 1.1.

[0303] As described above, the applicant has observed experimentally that by controlling the above ratio R1 between the rigidity characteristics related to the value of the dynamic elastic modulus E' and the ratio R2 between the hysteresis characteristics related to the value of tandelta to be close to 1, it may be advantageous to have an optimal dynamic hysteresis behavior both under the "hot" operating conditions of the tire and at the same time improve the drivability and grip performance on the road under the "cold" operating conditions.

[0304] The front tire 1 may also be provided with one or more of the above preferred features, thereby achieving the corresponding advantageous technical effects.

[0305] The present invention will now be illustrated by some examples, considering only for illustrative purposes and not for limiting purposes.

[0306] Properties of the Vulcanized Elastomer Composition

[0307] In Table 2 below, examples of elastomeric compositions are given for illustrative purposes only, which in a particularly preferred embodiment of the front tire 1 are made, after vulcanization, into a first vulcanized elastomeric material and a second vulcanized elastomeric material.

[0308] The amounts of the various components in the elastomeric composition are in phr and are as defined at the bottom of Table 1 above.

[0309] Table 2

[0310]

[0311]

[0312] * phr of dry polymer without extender oil

[0313] Table 3 below gives the results of static mechanical analysis and dynamic mechanical analysis carried out on composition samples of the aforementioned first vulcanized elastomeric material for the central annular portion L1 and the radially inner portion 12 of the radially outer portion 11 of the tread band 8 of the front tire 1 according to the invention, and of the second vulcanized elastomeric material for the lateral annular portions L2, L3 of the radially outer portion 11, the formulations of which have been indicated in Table 2 above.

[0314] These analyses were carried out under temperature and frequency conditions and using the methods indicated earlier.

[0315] Table 3

[0316]

[0317]

[0318] CA1: Load at 100% elongation

[0319] CA3: Load at 300% elongation

[0320] Table 4 below gives the ratios R1 between the dynamic mechanical properties of the elastic modulus E' between the various vulcanized elastomeric materials indicated earlier and the ratio R2 between tandelta within each vulcanized elastomeric material, provided they are in line with the purposes of the invention.

[0321] Table 4

[0322]

[0323] It can be clearly seen from Table 4 that the values of the ratios R1 and R2 are close to 1, indicating that the second vulcanized elastomeric material and the first vulcanized elastomeric material respectively exhibit homogeneous behavior under the "cold" and "hot" service conditions.

[0324] In this way and as described above, these vulcanized elastomeric materials allow to maintain optimal drivability and grip performance under "hot" usage conditions, and at the same time improve the drivability and grip performance under "cold" usage conditions of the front tires, as will be explained in more detail below with reference to tests carried out outdoors on a comparative tire and a tire according to the invention.

[0325] Tire Outdoor Test

[0326] In order to seek performance improvement, the applicant carried out comparative driving tests on a super sports tire for the front wheel with a size of 120 / 70ZR17 and a lateral curvature ratio of approximately equal to 0.42.

[0327] The tire according to the invention has the "crown base" construction of the tread band as described above with reference to Figure 2 In this tire, the tread band is manufactured using the compound given in Table 2 with the mechanical properties listed in Tables 3 and 4. The performance of this tire is compared with the performance of a comparative tire that is similar in size and structure but different only in the construction and composition of the tread band.

[0328] In this case, the comparative tire for the front wheel is for track applications and is approved for road applications, and has a tread band construction of a single compound type, which is the conventional configuration for such tires.

[0329] The tread band of the comparative tire is made of the materials given in Table 5 below.

[0330] Table 5 - Comparative Tire

[0331] Composite Single Elastomer Material of the Tread Band S-SBR 1 98 S-SBR 2 40 CB 80 Processing Oil 15 Resin 1 14 Resin 2 1.5 Stearic Acid 1.5 Zinc Oxide 5 Antioxidant 2 Sulfur 2.5 Vulcanization Accelerator 2.5 Vulcanization Retarder 0.2

[0332] * phr of dry polymer without extender oil

[0333] S-SBR 1: Solution-polymerized styrene-butadiene copolymer (phr given as dry polymer, 37.5 phr of TDAE oil added per 100 phr of dry elastomeric polymer) - SBR 1789 (Synthos)

[0334] S-SBR 2: Solution-polymerized styrene-butadiene copolymer (phr given as dry polymer, 37.5 phr of TDAE oil added per 100 phr of dry elastomeric polymer) - HP755 (JSR)

[0335] CB: CRX TM 1391 (Cabot)

[0336] Extender oil: TDAE (Nynas)

[0337] Resin 1: Hydrocarbon resin - (Flexys)

[0338] Resin 2: Hydrocarbon resin - RASINA BM01 (SER)

[0339] Stearic acid: Stearic acid (Wilmar)

[0340] Zinc oxide: (Zincol Ossidi)

[0341] Antiozonant: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine - (Eastman)

[0342] Sulfur: 90P (Rhein Chemie)

[0343] Accelerator: N-tert-butylbenzothiazole sulfenamide - TBBS 80 (Rhein Chemie)

[0344] Vulcanization retarder: N-(cyclohexylthio)phthalimide - PVI (Akrochem)

[0345] Different test tasks were carried out on a private track by performing a series of maneuvers to test adhesion and controllability under both dry and wet conditions. The driver's evaluation represents the average of the evaluations obtained from various maneuvers.

[0346] In the tests on dry ground, the conditions were as follows.

[0347] Tire inflation pressure: 2.3 bar; Track asphalt temperature: 45 °C; Air temperature: 30 °C.

[0348] In the tests on wet ground, the conditions were as follows.

[0349] Tire inflation pressure: 2.5 bar; Track asphalt temperature: 29 °C; Air temperature: 30 °C.

[0350] Tests were carried out using a BMW S1000RR motorcycle in the "Super Sport" segment.

[0351] Tables 6 and 7 below summarize the scores given by the testers for various types of performance expected for the test tires in the tests on dry ground and wet ground, respectively.

[0352] In Tables 6 and 7, the performance of the comparison tires is indicated by the symbol " / ", while for the performance of the tires according to the present invention, the symbol "=" is used to indicate an evaluation of the same performance as the comparison tires, and the symbol "+" is used to indicate an improvement in performance relative to the comparison tires, and the greater the number of the symbol "+", the greater the performance improvement.

[0353] Table 6 (Tests on dry ground)

[0354]

[0355] Table 7 (Tests on wet ground)

[0356] Tire Comparative Front Tire Front Tire According to the Invention Front Grip / ++ Traction During Braking / ++ Sense of Security / ++ Driving Precision / ++ Drive / Thrust / ++

[0357] It was also found during the tests carried out that using the tyre according to the invention can significantly reduce the lap times on the test track.

[0358] The results given in Tables 6 and 7 show that the tyre according to the invention exhibits a greater improvement in both adhesion and handling compared to the reference tyres, which are already excellent on wet ground, and also a greater improvement in the camber angle, which is usually not achievable with the front tyres on wet roads.

[0359] The results given in Tables 6 and 7 also show that the tyre according to the invention exhibits a similar or even improved behaviour with respect to its performance on dry ground.

[0360] Various modifications can be made to the embodiments described in detail, which still fall within the scope of protection of the present invention, and the scope of protection of the present invention is defined by the following claims.

Claims

1. A motorcycle front tire (1), said motorcycle front tire comprising an equatorial plane (X-X) and a tread band (8) having an entire axial extension (L), wherein, The tread band (8) comprises: a) a radially outer portion (11), which comprises: a1) a central annular portion (L1) which is arranged across the equatorial plane (X-X) of the front motorcycle tyre (1) and is made of a first vulcanised elastomeric material, and a2) a pair of lateral annular portions (L2, L3) which are arranged on opposite sides of the central annular portion (L1) with respect to the equatorial plane (X-X) of the front motorcycle tyre (1), the lateral annular portions (L2, L3) being made of a second vulcanised elastomeric material; b) a radially inner portion (12) which is below the radially outer portion (11) of the tread band (8) and extends along the entire axial extension of the tread band, the radially inner portion (12) being made of the first vulcanised elastomeric material; wherein the ratio R1 between the dynamic elastic modulus E' of the second vulcanised elastomeric material of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8), measured at a frequency of 10 Hz and a temperature of 23 °C, and the dynamic elastic modulus E' of the first vulcanised elastomeric material of the central annular portion (L1) and the radially inner portion (12) of the radially outer portion (11) of the tread band (8), measured at a frequency of 10 Hz and a temperature of 23 °C, is comprised between 0.6 and 1.2, preferably between 0.7 and 1.1; and wherein the ratio R2 between the loss factor of the second vulcanised elastomeric material of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8), measured at a frequency of 10 Hz and a temperature of 70 °C, and the loss factor of the first vulcanised elastomeric material of the central annular portion (L1) and the radially inner portion (12) of the radially outer portion (11) of the tread band (8), measured at a frequency of 10 Hz and a temperature of 23 °C, is comprised between 0.6 and 1.2, preferably between 0.7 and 1.

1.

2. The motorcycle front tire (1) according to claim 1, wherein, The first vulcanised elastomeric material of the central annular portion (L1) and the radially inner portion (12) 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 a temperature of 23 °C which is comprised between 5.7 MPa and 7.1 MPa, the dynamic elastic modulus E' preferably being comprised between 6.0 MPa and 6.4 MPa.

3. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The first vulcanised elastomeric material of the central annular portion (L1) and the radially inner portion (12) of the radially outer portion (11) of the tread band (8) has a loss factor measured at a frequency of 10 Hz and a temperature of 23 °C which is comprised between 0.37 and 0.47, the loss factor preferably being comprised between 0.41 and 0.

45.

4. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The second vulcanized elastomeric material of the lateral annular portions (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 and comprised between 5.2 MPa and 6.5 MPa, the dynamic elastic modulus E' preferably being comprised between 5.6 MPa and 6.0 MPa.

5. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The second vulcanized elastomeric material of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) has a loss factor measured at a frequency of 10 Hz and 70 °C and comprised between 0.34 and 0.44, the loss factor preferably being comprised between 0.38 and 0.

40.

6. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The first vulcanized elastomeric material of the central annular portion (L1) of the radially outer portion (11) of the tread band (8) and of the radially inner portion (12) is obtained by vulcanizing an elastomeric material comprising 100 phr of at least one elastomeric diene polymer and from 70 phr to 110 phr of a white reinforcing filler, the white reinforcing filler preferably comprising an inorganic material, the amount of which, by weight, is equal to or greater than 80% of the total weight of the white reinforcing filler, more preferably equal to or greater than 85%, more preferably equal to or greater than 90%, more preferably equal to or greater than 95%, the inorganic material being selected from silica, alumina, silicates, hydroaluminates, calcium carbonate, kaolin, titanium dioxide and mixtures thereof.

7. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The second vulcanized elastomeric material of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is obtained by vulcanizing an elastomeric material comprising 100 phr of at least one elastomeric diene polymer and from 40 phr to 100 phr of a carbon black reinforcing filler, the amount of the carbon black reinforcing filler preferably being from 50 phr to 90 phr, more preferably from 60 phr to 80 phr.

8. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The central annular portion (L1) of the radially outer portion (11) of the tread band (8) extends transversely over 5% - 25% of the semi-axial extension of the tread band (8), preferably over 10% - 20% of the semi-axial extension of the tread band.

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

10. The motorcycle front tire (1) according to any one of the preceding claims, wherein, Each of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is arranged axially outside and adjacent to the central annular portion (L1) so as to define an interface (16) separating the central annular portion (L1) from the lateral annular portions (L2, L3) in the axial direction.

11. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) extend transversely along 75% - 95% of the semi-axial extension (L / 2) of the tread band (8), preferably along 80% - 90% of the semi-axial extension of the tread band.

12. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The central annular portion (L1) of the radially outer portion (11) of the tread band (8) is substantially free of grooves.

13. The motorcycle front tire (1) according to any one of the preceding claims, wherein, The lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) each include 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). And wherein, the front motorcycle tire (1) includes a plurality of grooves (13, 14) formed in the first lateral annular sub-portions (L2’, L3’) of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8).

14. The motorcycle front tire (1) according to claim 13, wherein, The first lateral annular sub-portions (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% of the semi-axial extension (L / 2) of the tread band (8), preferably along 45% - 60% of the semi-axial extension of the tread band.

15. The front motorcycle tire (1) according to any one of claims 13 to 14, wherein, The total void rubber ratio defined by the plurality of grooves (13, 14) in the tread band (8) is greater than or equal to 4% and less than or equal to 8%, preferably greater than or equal to 4% and less than or equal to 5%.

16. The front motorcycle tire (1) according to any one of claims 13 to 15, wherein, The void rubber ratio defined by the plurality of grooves (13, 14) in each first lateral annular sub-portion (L2’, L3’) of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is greater than or equal to 0% and less than or equal to 30%, preferably greater than or equal to 0% and less than or equal to 25%.

17. The front motorcycle tire (1) according to claim 16, wherein, The void rubber ratio defined by the plurality of grooves (13, 14) in the first annular segment (A) of each first lateral annular sub-portion (L2’, L3’) of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) increases along the semi-axial extension (L / 2) of the tread band (8) as it moves away from the equatorial plane (X-X) of the front motorcycle tire (1) from the interface (16), and the first annular segment is arranged axially outside and adjacent to the central annular portion (L1).

18. The front motorcycle tire (1) according to claim 17, wherein, The first annular segment (A) extends transversely along 5% - 25% of the semi-axial extension (L / 2) of the tread band (8) from the ends (17, 18) of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) proximal to the equatorial plane (X-X), preferably along 10% - 20% of the semi-axial extension of the tread band.

19. The front motorcycle tire (1) according to claim 17 or 18, wherein, In the first annular segment (A), the void rubber ratio increases from a minimum of approximately 0% at the ends (17, 18) proximal to the equatorial plane (X-X) of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) to a maximum between 20% and 30% at the axially outer end (A') of the first annular segment (A).

20. The front motorcycle tire (1) according to claim 19, wherein, The axially outer end (A') of the first annular segment (A) is arranged at a distance from the equatorial plane (X-X) of the motorcycle front tire (1), the distance being at least 13% of the semi-axial extension L / 2 of the tread band (8), preferably between 15% and 35% of the semi-axial extension.

21. The front motorcycle tire (1) according to any one of claims 17 - 20, wherein, The void rubber ratio defined in the second annular segment (B) of each first lateral annular sub-portion (L2', L3') of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) decreases along the axial extension of the tread band (8) from the first annular segment (A) as it moves away from the equatorial plane (X-X) of the motorcycle front tire (1), the second annular segment being arranged axially outside and adjacent to the first annular segment (A).

22. The front motorcycle tire (1) according to claim 21, wherein, The second annular segment (B) extends transversely from the first annular segment (A) by 15% - 60% of the semi-axial extension (L / 2) of the tread band (8), preferably by 25% - 50% of the semi-axial extension of the tread band.

23. The front motorcycle tire (1) according to claim 20 or 22, wherein, In the second annular segment (B), the void rubber ratio decreases from a maximum of approximately 25% at the axially outer end (A') of the first annular segment (A) to a minimum of approximately 0% at the axially outer end of the first lateral annular sub-portion (L2', L3') of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8).

24. The front motorcycle tire (1) according to claim 23, wherein, The axially outer end of the first lateral annular sub-portion (L2', L3') of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is arranged at a distance from the equatorial plane (X-X) of the motorcycle front tire (1), the distance being at least 55% of the semi-axial extension (L / 2) of the tread band (8), preferably at least 60% of the semi-axial extension of the tread band.

25. The front motorcycle tire (1) according to any one of claims 12 to 24, wherein, The second lateral annular sub-portions (L2", L3") of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) extend transversely by 10% - 55% of the semi-axial extension (L / 2) of the tread band (8), preferably by 20% - 45% of the semi-axial extension of the tread band.

26. The front motorcycle tire (1) according to any one of claims 12 - 25, wherein, Each second lateral annular sub-portion (L2", L3") of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is substantially free of grooves.

27. The front motorcycle tire (1) according to any one of the preceding claims, wherein, The lateral curvature ratio of the front motorcycle tire is equal to or greater than 0.35 and equal to or less than 0.50, preferably equal to or greater than 0.39 and equal to or less than 0.45, and more preferably equal to or greater than 0.40 and equal to or less than 0.44.

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