Tire for motorcycle

Abstract

A tire (1) for a motorcycle wheel is described which comprises a "cap and base" type tread band (8) having a radially outer portion formed by a central sub-portion (11a) made of a first vulcanized elastomer material and a pair of lateral sub-portions (11b, 11c) made of a second vulcanized elastomer material, and a radially inner portion (12) made of a third vulcanized elastomer material. The first vulcanized elastomer material of the central sub-portion (11a) has a dynamic elastic modulus (E') measured under the same conditions that is greater than the dynamic elastic modulus (E') of the second vulcanized elastomer material of the lateral sub-portions (11b, 11c), measured at a frequency of 10 Hz and 23 °C. Both such vulcanized elastomer materials are included between 5.2 and 6.5 MPa and each has a dynamic elastic modulus (E') measured under the same conditions that is greater than the dynamic elastic modulus (E') of the third vulcanized elastomer material, measured at a frequency of 10 Hz and 23 °C. In this tire (1), the ratios R1 and R2 of the dynamic elastic modulus and tanδ of the second vulcanized elastomer material of the lateral sub-portions (11b, 11c) of the radially outer portion, measured at a frequency of 10 Hz and 100 °C, to the dynamic elastic modulus and tanδ of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8), measured at a frequency of 10 Hz and 70 °C, are included between 0.8 and 1.2.

Description

Technical Field

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

[0002] In particular, the present invention relates to a tire for a "super sports" and / or "hyper sports" motorcycle that is also used on a race track and has a large displacement (e.g., 600 or 1000 cm 3 or more) and / or a large output (e.g., 200 horsepower or more).

[0003] Even more specifically, the present invention relates to a high-performance tire intended to be mounted on the rear wheel of a motorcycle, in other words, a tire capable of maintaining a maximum speed of at least about 210 km / h, or a tire capable of withstanding a maximum load of at least about 210 kg, or a tire having both of these capabilities.

Background Art

[0004] Tires for motorcycles are known, for example, from European Patent Application Publication No. 2662226 (A1) and International Publication No. 2019 / 082012.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Recently, it has been observed that there is a tendency for large-output motorcycles for super sports or hyper sports to be introduced into the market. In fact, for example, there are motorcycles for general roads with a displacement of 1000 cm 3 or more and a horsepower of 200 or more in the market.

[0006] The applicant has noticed that the demand for the use of such super sports motorcycles on both general roads and race tracks is increasing.

[0007] Parallel to this, the Applicant has noticed that there is an increasing demand for high-performance tires for very demanding sports driving (e.g., on a race track) and for both the lifespan and handling in all weather and seasonal conditions (for the use of motorcycles on public roads throughout the year).

[0008] In this regard, the Applicant has observed, in particular, the recent trend that users desire, for tires mounted on supersport motorcycles, handling performance and load-holding performance in wet and / or low-temperature climatic conditions or non-optimal road surface conditions (hereinafter also referred to as "low-temperature" usage conditions), as well as handling performance and performance under extreme speed and maneuvering conditions on dry and / or high-temperature ground (hereinafter also referred to as "high-temperature" usage conditions), and to keep the tire performance as constant as possible over a long period.

[0009] Satisfying such contrasting requirements with a single set of tires is an especially challenging task if the solutions are contrasting with each other. Typically, different adjustments are adopted for each of the above requirements to apply a solution suitable for a specific problem.

[0010] In order to improve the handling performance and performance on dry and / or high-temperature ground, as well as on wet and / or low-temperature climatic conditions or non-optimal road surfaces, it is necessary, in particular, to ensure an optimal grip on the ground under these different driving conditions.

[0011] To improve the grip of the tire, during the manufacture of the tread band, it is possible to use so-called soft types of vulcanized elastomer materials (also defined in this specification by the term "rubber compound") to better adapt to the roughness of the road surface that reflects the irregular profile of the road surface. These vulcanized elastomer materials typically feature a low elastic modulus and / or a high hysteresis.

[0012] However, the applicant has observed that if the rubber compound is too soft, the driving stability on a straight course decreases and the tire life becomes shorter.

[0013] To overcome the above problems, tires having tread bands made of different rubber compounds have been proposed. Typically, a softer rubber compound is used in the shoulder portion and a less soft rubber compound is used in the crown portion.

[0014] A tire configured in this way is described, for example, in European Patent No. 2662226.

[0015] However, in relation to this configuration of the tread band, the applicant has observed that the handling performance and performance of the tire under "high temperature" usage conditions tend to decrease, particularly in the case of extreme usage such as on a race track, and the service life of the tire is significantly impaired.

[0016] To meet the above contrasting requirements with a single set of tires, for example, as described in International Publication No. 2019 / 082012 in the name of the applicant, tires having tread bands made of different rubber compounds, typically rubber compounds with a high carbon black filler content in the shoulder portion and several rubber compounds with a high white filler content in the crown portion and the intermediate annular portion of the tread band, have also been proposed, all of which are combined with an appropriate distribution and arrangement of the grooves in the tread band at the interface between rubber compounds of different compositions.

[0017] Finally, the Applicant has observed that a highly rigid tire structure typical for use on a race track, with the tire deflated by a fraction of a bar relative to the pressure recommended by the manufacturer in order to increase the contact area so as to be able to adequately cope with extreme maneuvers, is not very suitable for general road use where the tire inflated to the pressure recommended by the manufacturer is required to provide comfort, load holding, and the ability to absorb loads on various road surfaces.

[0018] In the pursuit of continuous improvement of motorcycle tires, the Applicant has set itself two objectives: to improve the handling performance and tire performance under "high temperature" usage conditions and to keep them constant for as long as possible without sacrificing the handling and load holding performance under the aforementioned "low temperature" usage conditions of the tire.

Means for Solving the Problem

[0019] The Applicant has found that it is possible to achieve such two objectives by adopting the so-called "cap-and-base" configuration of the tread band and using a vulcanized elastomer material having appropriate dynamic mechanical properties under the "low temperature" and "high temperature" usage conditions of the tire.

[0020] In particular, the Applicant has found that for this purpose, it is necessary to simultaneously adopt the following clauses. i) Using the configuration of the radially outer portion of a tread band of the type comprising a central sub-portion disposed across the equatorial plane of the tire and a pair of lateral sub-portions distal to the equatorial plane of the tire and disposed on both sides of this central sub-portion, and ii) Using a vulcanized elastomer material having specific dynamic mechanical properties under the respective "high temperature" and "low temperature" usage conditions of the tire for each portion of the tread band.

[0021] In this regard, the Applicant has also found it necessary to evaluate the dynamic mechanical properties of the vulcanized elastomer materials used to manufacture different parts of the tread band in a differentiated manner for each elastomer material and under specific stress and temperature conditions that can be correlated with the actual service conditions of each material, which are subjected to different types of stress and different temperatures depending on their position in the tread band during the use of the tire.

[0022] As far as the "low-temperature" use of the tire is concerned, the Applicant has in particular found that the dynamic mechanical properties predicting the behavior of the tire under such service conditions for all of the elastomer materials forming the tread band are the storage modulus E' and tanδ measured at a frequency of 10 Hz and 23°C.

[0023] Conversely, as far as the "high-temperature" use of the tire is concerned, the Applicant has found that the dynamic mechanical properties predicting the behavior of the tire under such service conditions are - for the vulcanized elastomer material of the central sub-part of the radially outer part of the tread band and the vulcanized elastomer material of the radially inner part of the tread band, at a frequency of 10 Hz and 70°C, and - for the vulcanized elastomer material of the lateral sub-part of the radially outer part of the tread band, at a frequency of 10 Hz and 100°C the storage modulus E' and tanδ measured respectively.

[0024] Therefore, the Applicant's desired goal of maintaining the handling and load-holding performance of the tire under the aforementioned "low-temperature" service conditions of the tire is - in the central sub-part of the radially outer part of the tread band, a first vulcanized elastomer material having a storage modulus E' measured at a frequency of 10 Hz and 23°C, which is greater than the storage modulus E' measured at a frequency of 10 Hz and 23°C of a second vulcanized elastomer material used in the lateral sub-part of the radially outer part of the tread band, and - In the radially inner part of the tread band, a third vulcanized elastomer material having a dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C, which is lower than the dynamic elastic modulus E' of the aforementioned first and second elastomer materials measured at a frequency of 10 Hz and 23°C has been found to be achievable by using.

[0025] On the other hand, as far as the "high temperature" use of the tire is concerned, the applicant aims to improve the handling and performance of the tire and keep it constant for as long as possible, - By keeping the ratio of the "high temperature" dynamic elastic modulus (E') of the second vulcanized elastomer material used in the lateral sub-part of the radially outer part of the tread band to the dynamic elastic modulus (E') of the third vulcanized elastomer material used in the radially inner part of the tread band close to 1, that is, by keeping the dynamic elastic modulus (E') of such materials very similar to each other, and - By keeping the ratio of the "high temperature" tanδ of the second vulcanized elastomer material to the "high temperature" tanδ of the third vulcanized elastomer material, and the ratio of the "high temperature" tanδ of the first vulcanized elastomer material to the "high temperature" tanδ of the third vulcanized elastomer material close to 1, that is, by keeping the tanδ of such materials very similar to each other has been found to be achievable simultaneously.

[0026] The applicant has surprisingly found that by controlling the coefficient values and hysteresis values, particularly the tanδ values, of the vulcanized elastomer materials used to make various parts of the tread band, which are correlated with the tire's usage conditions, within a specific ratio range according to the area of the tread band under consideration, it is possible to improve both the "high temperature" handling and load holding performance of the tire without sacrificing the handling and load holding performance of the tire under the aforementioned "low temperature" usage conditions, and maintain them at an optimal level for a long time.

[0027] In particular, by using a so-called "soft" vulcanized elastomer material having a lower elastic modulus and a higher hysteresis than the vulcanized elastomer material used in the radially outer portion of the tread band under both low temperature and high temperature conditions in the radially inner portion of the tread band, it has been surprisingly achieved to improve and maintain the handling and performance of the tire under "high temperature" usage conditions over a long period of time.

[0028] Using such a "soft" vulcanized elastomer material in the radially inner portion of the tread band not only has been considered unsuitable for providing constant performance over a long period of time under such usage conditions, but on the contrary, it has been likely to rapidly degrade the performance of the tire. Therefore, it is surprising to improve and maintain the handling and performance of the tire under "high temperature" usage conditions.

[0029] Accordingly, the present invention relates to a tire for a motorcycle.

[0030] Such a tire for a motorcycle includes an equatorial plane and a tread band, and the tread band a) a radially outer portion, and a1) a central sub-portion disposed across the equatorial plane of the tire and made of a first vulcanized elastomer material, and a2) a pair of lateral sub-portions distal to the equatorial plane of the tire and disposed on both sides of this central sub-portion, the pair of lateral sub-portions made of a second vulcanized elastomer material, wherein the first vulcanized elastomer material of the central sub-portion has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is greater than the dynamic elastic modulus (E') of this second vulcanized elastomer material of the lateral sub-portions measured at a frequency of 10 Hz and 23°C, and the first vulcanized elastomer material of this central sub-portion and the second vulcanized elastomer material of the lateral sub-portions each have a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is included between 5.2 and 6.5 MPa, a radially outer portion, b) a radially inner portion that extends along the entire axial development portion below the radially outer portion of the tread band, the third vulcanized elastomer material having a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C being lower than that of the first vulcanized elastomer material of the central sub-portion of the radially outer portion of the tread band and the second vulcanized elastomer material of the lateral sub-portion of the radially outer portion of the tread band, and comprising a radially inner portion made of a third vulcanized elastomer material having a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C, The ratio R1 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer material of the lateral sub-portion of the radially outer portion of the tread band to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion of the tread band is included between 0.8 and 1.2, The ratio R2 of the tanδ measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer material of the lateral sub-portion of the radially outer portion of the tread band to the tanδ measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion of the tread band is included between 0.8 and 1.2.

[0031] The Applicant has experimentally found that by using a so-called "cap and base" type of tread band having the aforementioned characteristics, it is surprisingly possible to improve and maintain over a long period the handling and performance of a tire under "high temperature" use conditions of a motorcycle tire, particularly a "super sports" and / or "hyper sports" motorcycle tire, without substantially changing the handling and road holding performance in wet and / or low temperature climatic conditions, or on a non-optimal road surface.

[0032] Without wishing to be bound by any theory of interpretation, the Applicant believes that under "high temperature" use conditions, a tire as defined above has a substantially uniform dynamic and hysteresis behavior of the tread band in the shoulder region, i.e., the region most stressed under such use conditions.

[0033] The Applicant believes that this substantially uniform dynamic and hysteresis behavior advantageously limits the premature wear phenomenon and the deterioration of tire performance, i) the ratio between the deformation characteristics of a second vulcanized elastomer material present in the lateral or shoulder sub - portion of the radially outer portion of the tread band and a third vulcanized elastomer material present in the radially inner portion of the tread band - which correlates with the value of the dynamic elastic modulus (E’) under each of the "high - temperature" service conditions specified above - and ii) the ratio between the hysteresis characteristics of the second vulcanized elastomer material and the third vulcanized elastomer material - which correlates with the tanδ value under each of the "high - temperature" service conditions specified above - can be achieved by controlling it to a value close to 1.

[0034] Surprisingly, as outlined above, this advantageous technical effect is observed in the service conditions of the tire by using, in the radially inner portion of the tread band, a third vulcanized elastomer material having a lower elastic modulus and a higher tanδ than the second vulcanized elastomer material used in the shoulder region of the radially outer portion of the tread band. These are characteristics that were thought to cause a rapid decline in performance under the "high - temperature" service conditions of the tire, but it has been found that this is not actually the case. Instead, the third vulcanized elastomer material was able to actually improve and maintain the handling and performance of the tire under "high - temperature" service conditions over a long period.

[0035] Conversely, also in this case, although not wishing to be bound by any theory of interpretation, the Applicant believes that in the "low temperature" use conditions of the tire, the third vulcanized elastomer material present in the radially inner part of the tread band is subject to deformation (correlated with the elastic modulus E') and hysteresis phenomena (correlated with the tanδ parameter), whereby it can "heat" the radially outer part of the tread band thereon (which is harder and has less hysteresis), so that the radially outer part of the tread band can adhere better to a wet and / or low temperature ground, thereby obtaining sufficient handling and load holding performance under these use conditions.

[0036] Basically, in the tire according to the present invention, there is an effective convergence of the hysteresis characteristics in the shoulder region of the tread band of the tire, and improvement and long-term maintenance of the handling and load holding performance under extreme speed and steering conditions on a dry and / or hot ground under "high temperature" use conditions, while at the same time having an effective differentiation of the stiffness and hysteresis characteristics between different parts of the tread band under the "low temperature" use conditions of the tire, maintaining the handling and load holding performance in wet and / or low temperature climatic conditions or on a non-optimal road surface.

[0037] In particular, under "high temperature" use conditions, the assembly formed by the lateral or shoulder sub-part of the radially outer part of the tread band and the part below such a sub-part of the tire according to the present invention in the radially inner part of the tread band behaves as if it were substantially constituted by a single vulcanized elastomer material having optimal characteristics under these use conditions from the viewpoints of deformability and hysteresis.

[0038] Advantageously, therefore, the tire according to the present invention not only achieves an improvement in the handling and load holding performance under extreme speed and steering conditions on a dry and / or hot surface, but can also maintain such performance for a longer period.

[0039] Furthermore, in the "high temperature" usage conditions, the assembly formed by the central sub - portion of the radially outer portion of the tread band and the portion below such a sub - portion of the tire according to the present invention in the radially inner portion of the tread band behaves optimally from the viewpoints of deformability and hysteresis even under the straight - course driving conditions where it is necessary to attenuate as much as possible any unevenness of the road surface.

[0040] In this specification and the following claims, all numerical entities indicating amounts, parameters, percentages, etc. should be understood to be preceded by the term "about" in all cases, unless otherwise indicated. Further, all ranges of numerical entities include, in addition to the ranges specifically shown hereinbelow, all possible combinations of the maximum and minimum numerical values, as well as all possible intermediate ranges.

[0041] Unless otherwise indicated, all ranges of numerical entities also include the maximum and minimum numerical values.

[0042] For the purposes of the present invention, the following definitions apply.

[0043] The term "phr" (an acronym for "per hundred parts" per 100 parts by weight of elastomeric polymer excluding plasticized extender oil) indicates the parts by weight of a given component of an elastomeric rubber compound per 100 parts by weight of elastomeric polymer.

[0044] The terms "elastomeric material", "rubber", "elastomeric polymer", or "elastomer" are used to denote a material that includes a vulcanizable natural or synthetic polymer and a reinforcing filler, and such a material can be deformed by force at room temperature after being vulcanized and can quickly and strongly return substantially to its original shape and size after the deforming force is removed (according to the definition of standard terms for rubber in ASTM D1566 - 11).

[0045] The term "diene polymer" is used to denote a polymer or copolymer obtained from the polymerization of one or more different monomers, at least one of which is a conjugated diene (conjugated diolefin).

[0046] The term "rubber compound" or "elastomeric rubber compound" is used to denote a mixture obtained by mixing at least one elastomeric polymer with at least one of the additives commonly used in the preparation of tire rubber compounds and optionally heating.

[0047] The term "vulcanizable rubber compound" or "vulcanizable elastomeric rubber compound" is used to denote a vulcanizable elastomeric mixture obtained by compounding all the additives including a vulcanizing agent into an elastomeric rubber compound.

[0048] The term "vulcanized elastomeric material" is used to denote a material obtained by vulcanizing a vulcanizable elastomeric rubber compound.

[0049] The term "vulcanization" is used to denote the crosslinking reaction of natural or synthetic rubber induced by a crosslinking agent, typically sulfur-based.

[0050] The term "vulcanizing agent" is used to denote a compound that can change natural or synthetic rubber into an elastic and strong 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, bis[(trialkoxysilyl)propyl] polysulfide, thiuram, dithiomorpholine, and sulfur donors such as caprolactam disulfide.

[0051] The term "vulcanization accelerator" is used to denote compounds such as sulfur donors, for example TBBS, sulfenamides in general, thiazoles, dithiophosphates, dithiocarbamates, guanidines, and thiurams, which enable shortening of the duration of the vulcanization process and / or reduction of the operating temperature.

[0052] The term "vulcanization activator" is used to denote compounds that further accelerate vulcanization, thereby enabling vulcanization to be carried out in a shorter time and, in some cases, at a lower temperature. An example of an activator is the stearic acid-zinc oxide system.

[0053] The term "vulcanization retarder" is used to denote compounds, such as N-(cyclohexylthio)phthalimide (CTP), that can delay the start of the vulcanization reaction and / or suppress unwanted secondary reactions.

[0054] The term "reinforcing filler" is used to denote reinforcing materials typically used in the art, preferably selected from carbon black and "white fillers", to improve the mechanical properties of the rubber in a tire.

[0055] The term "white filler" is used to denote conventional silica and silicates, for example, preferably amorphous silica precipitated with a strong acid, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicates, kaolin, silicate fibers, for example, palygorskite also known as attapulgite, sepiolite, montmorillonite, halloysite and other phyllosilicate minerals, optionally modified by acid treatment and / or derivatization, and conventional reinforcing materials selected from mixtures thereof used in the art. Typically, white fillers have surface hydroxyl groups.

[0056] The term "motorcycle tire" is used to denote a tire having a large curvature ratio (typically greater than 0.20) and capable of achieving a large camber angle during cornering.

[0057] The term "curvature ratio" is used to indicate the ratio between the distance included between the radially highest point of the tread band and the maximum width of the radial cross-section of the tire (such a distance is also shown as an "arrow") in the cross-section of the tire, and the same maximum width of the tire (also called the "maximum chord").

[0058] The term "axial development" of the tread band or a part thereof is used to indicate the development of the radially outermost profile of the tread band or a part thereof in the cross-section of the tire, which is performed by a plane including the rotation axis of the tire.

[0059] The term "axial half-development" of the tread pattern of the tread band or a part thereof is used to indicate the development of the radially outermost profile of the tread band or a part thereof from the equatorial plane towards the axially outermost end of the tire in the cross-section of the tire, which is performed by a plane including the rotation axis of the tire.

[0060] The term "equatorial plane" of the tire is used to indicate a plane that is perpendicular to the rotation axis of the tire and symmetrically bisects the tire.

[0061] The term "width" is used to indicate a dimension measured along a direction perpendicular to the equatorial plane.

[0062] The term "tread pattern" is used to represent all parts (including grooves) of the tread band in a plane that is perpendicular to the equatorial plane of the tire and in contact with the maximum diameter of the tire. The tread pattern is defined by a plurality of land parts separated by grooves and may include sipes in some cases.

[0063] The terms "radial direction" and "axial direction", as well as the expressions "radially inner / outer" and "axially inner / outer", are used to refer 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, that is, a direction substantially perpendicular to the rotation axis of the tire and a direction substantially parallel to the rotation axis of the tire, respectively.

[0064] The terms "circumferential" and "circumferentially" are used to refer to the direction of circumferential development of the tire, that is, the rolling direction of the tire, which corresponds to the direction of a plane that coincides with or is substantially parallel to the equatorial plane of the tire.

[0065] The term "circumferential development portion" of a tire, or a tread band, or a part thereof is used to indicate the planar development of the radially outermost surface of the tire, or the tread band, or a part thereof on a plane in contact with the tire.

[0066] The expressions "axially innermost" and "axially outermost" indicate a position close to the equatorial plane and a position far from the equatorial plane with respect to the reference element, respectively.

[0067] The term "radial carcass structure" is used to indicate a carcass structure provided with a plurality of reinforcing cords each oriented substantially axially in the crown portion of the tire. Such reinforcing cords can also be incorporated into a single carcass ply or several (preferably two) carcass plies overlapped radially with each other.

[0068] The term "substantially axial" is used to indicate a direction inclined at an angle included between 60° and 90° with respect to the equatorial plane of the tire.

[0069] The term "substantially circumferential" is used to indicate a direction facing an angle included between 0° and 20° with respect to the equatorial plane of the tire.

[0070] The term "static mechanical properties" of the tread rubber compound is used to indicate the stress-strain properties when pulling a thermoplastic rubber vulcanized according to UNI standard 6065:2001, measured at a predetermined temperature on a specimen of the rubber compound vulcanized at 170 °C for 10 minutes.

[0071] The term "dynamic mechanical properties" of the tread rubber compound is used to indicate the mechanical properties measured using an Instron dynamic device model 1341 in a tension-compression mode, as described herein.

[0072] Using a test piece of a material crosslinked at (170 °C, 15 minutes) in a cylindrical shape (length = 25 mm, diameter = 18 mm), a compression preload was applied until the longitudinal deformation reached 25% with respect to the initial length, and it was maintained at a predetermined temperature (e.g., 23 °C, 70 °C, and 100 °C) throughout the test. Following a 2-minute waiting time, after mechanical preconditioning with a deformation amplitude of 7.5%, 10 Hz, and 125 cycles with respect to the length under the preload, the test piece was subjected to a dynamic sinusoidal stress having an amplitude of ±3.5% with respect to the length under the preload at a predetermined frequency, e.g., 10 Hz. The dynamic mechanical properties are represented by the values of the dynamic elastic modulus (E') and tanδ (loss factor). The tanδ value was calculated as the ratio of the dynamic viscosity coefficient (E'') to the dynamic elastic modulus (E').

[0073] The present invention can have one or more of the following preferred features in one or more of the foregoing aspects, and these features can be combined as desired according to the application requirements.

[0074] Preferably, the first vulcanized elastomer material in the central sub-part and the second vulcanized elastomer material in the lateral sub-part of the radially outer part of the tread band have respective dynamic elastic moduli (E') measured at a frequency of 10 Hz and 23 °C, which are included between 5.8 and 6.4 MPa.

[0075] In this way, it is advantageously possible to have the appropriate stiffness characteristics of the tread band under the "low temperature" usage conditions of the tire.

[0076] Preferably, the ratio R1 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer material of the lateral sub - portion of the radially outer portion of the tread band to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion of the tread band is included between 0.9 and 1.1.

[0077] Advantageously, this preferred feature contributes to optimizing and substantially maintaining over a long period the handling and performance of the tire under extreme speed and steering conditions on dry and / or hot surfaces during cornering, since the shoulder region of the tread band of the tire is formed of a substantially "homogeneous" vulcanized elastomer material from the viewpoint of its "high temperature" deformation ability and from the viewpoint of its behavior on the road.

[0078] Preferably, the ratio R2 of the tanδ measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer material of the lateral sub - portion of the radially outer portion of the tread band to the tanδ measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion of the tread band is included between 0.9 and 1.1.

[0079] Also in this case, this preferred feature advantageously contributes to optimizing and substantially maintaining over a long period the handling and performance of the tire under extreme speed and steering conditions on dry and / or hot surfaces during cornering, since the shoulder region of the tread band of the tire is formed of a vulcanized elastomer material that is substantially "homogeneous" from the viewpoint of its "high temperature" deformation ability and from the viewpoint of its behavior on the road.

[0080] Preferably, the first vulcanized elastomer material of the central sub - portion of the radially outer portion of the tread band has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C, which is included between 5.1 and 5.5 MPa, more preferably between 5.2 and 5.4 MPa.

[0081] Preferably, the first vulcanized elastomer material of the central sub - portion of the radially outer portion of the tread band has a tanδ measured at a frequency of 10 Hz and 70 °C, which is included between 0.26 and 0.30, more preferably between 0.27 and 0.29.

[0082] Preferably, the second vulcanized elastomer material of the lateral sub - portion of the radially outer portion of the tread band has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 100 °C, which is included between 2.5 and 2.9 MPa, more preferably between 2.6 and 2.8 MPa.

[0083] Advantageously, this preferred feature contributes to achieving optimal ground contact performance and optimal grip of the tire on the ground so as to improve the handling and performance of the tire under "high - temperature" usage conditions.

[0084] Preferably, the second vulcanized elastomer material of the lateral sub - portion of the radially outer portion of the tread band has a tanδ measured at a frequency of 10 Hz and 100 °C, which is included between 0.24 and 0.28, more preferably between 0.25 and 0.27.

[0085] Also in this case, this preferred feature advantageously contributes to achieving optimal ground contact performance and optimal grip of the tire on the ground so as to improve the handling and performance of the tire under "high - temperature" usage conditions.

[0086] Preferably, the third vulcanized elastomer material of the radially inner portion of the tread band has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C, which is included between 2.5 and 2.9 MPa, more preferably between 2.6 and 2.8 MPa.

[0087] Advantageously, due to this preferred feature, the third vulcanized elastomeric material in the radially inner portion of the tread band can effectively contribute to achieving optimal handling and performance of the tire under "high temperature" service conditions.

[0088] Under such "high temperature" service conditions, in fact, the third vulcanized elastomeric material in the radially inner portion of the tread band is appropriately differentiated in various regions of the tread band and simultaneously has the characteristic of deformability correlated with the value of the dynamic elastic modulus (E') that enables achieving high stability characteristics from the perspective of dynamics as a whole of the tread band under "high temperature" service conditions.

[0089] The third vulcanized elastomeric material is in fact substantially the same as the second vulcanized elastomeric material in the shoulder sub-portion of the radially outer portion of the tread band and has much lower deformation characteristics than the first vulcanized elastomeric material in the central portion of the radially outer portion of the tread band, thereby being able to "resemble" the hysteresis behavior of the shoulder portion and "heat" the central sub-portion of the tread band formed by a rubber compound with low deformability.

[0090] Preferably, the third vulcanized elastomeric material in the radially inner portion of the tread band has a tanδ measured at a frequency of 10 Hz and 70 °C, which is included between 0.25 and 0.29, more preferably between 0.26 and 0.28.

[0091] Advantageously, due to this preferred feature, also, the third vulcanized elastomeric material in the radially inner portion of the tread band can effectively contribute to achieving optimal handling and performance of the tire under "high temperature" service conditions, and in this case, it has hysteresis characteristics correlated with the tanδ value that are substantially the same as the hysteresis characteristics of the first and second vulcanized elastomeric materials in the radially outer portion of the tread band.

[0092] Preferably, the first vulcanized elastomer material of the central sub-part of the radially outer part of the tread band has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is included between 6.0 and 6.5 MPa, more preferably between 6.2 and 6.4 MPa.

[0093] Preferably, the first vulcanized elastomer material of the central sub-part of the radially outer part of the tread band has a tanδ measured at a frequency of 10 Hz and 23°C, which is included between 0.40 and 0.44, more preferably between 0.41 and 0.43.

[0094] Preferably, the second vulcanized elastomer material of the lateral sub-part of the radially outer part of the tread band has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is included between 5.5 and 6.0 MPa, more preferably between 5.7 and 5.9 MPa.

[0095] Preferably, the second vulcanized elastomer material of the lateral sub-part of the radially outer part of the tread band has a tanδ measured at a frequency of 10 Hz and 23°C, which is included between 0.66 and 0.70, more preferably between 0.67 and 0.69.

[0096] In this way, it is advantageously possible to achieve an optimal grip of the tire on the ground so as to improve the handling and performance of the tire under "low temperature" usage conditions.

[0097] Preferably, the third vulcanized elastomer material of the radially inner part of the tread band has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is included between 4.0 and 5.0 MPa, more preferably between 4.2 and 4.5 MPa.

[0098] Advantageously, due to this preferred feature, the third vulcanized elastomer material of the radially inner part of the tread band can effectively contribute to achieving an optimal contact area on the ground and an optimal grip of the tire on the ground so as to improve the handling and performance of the tire under "low temperature" usage conditions.

[0099] Preferably, the third vulcanized elastomer material in the radially inner portion of the tread band has a tan δ measured at a frequency of 10 Hz and 23 °C, which is included between 0.49 and 0.53, more preferably between 0.50 and 0.52.

[0100] Advantageously, also due to this preferred feature, the third vulcanized elastomer material in the radially inner portion of the tread band can effectively contribute to achieving an optimal contact area and an optimal grip of the tire on the ground so as to improve the handling and performance of the tire under "low temperature" usage conditions.

[0101] Preferably, the ratio R3 between the tan δ measured at a frequency of 10 Hz and 70 °C of the first vulcanized elastomer material in the central sub-portion of the radially outer portion of the tread band and the tan δ measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material in the radially inner portion of the tread band is included between 0.5 and 1.2, more preferably between 0.7 and 1.0.

[0102] In this way, since the central region of the tread band of the tire is formed of a substantially "homogeneous" vulcanized elastomer material from the viewpoint of hysteresis in both the radially outer portion and the radially inner portion, it is advantageously possible to optimize the handling and performance of the tire under "high temperature" usage conditions even during straight running and keep them substantially constant over a long period of time.

[0103] Preferably, the ratio R4 between the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C of the first vulcanized elastomer material in the central sub-portion of the radially outer portion of the tread band and the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material in the radially inner portion of the tread band is included between 1.3 and 2.0, more preferably between 1.5 and 1.8.

[0104] In this way, from the perspective of its "high temperature" deformation ability, the central region of the tire tread band can well adapt to the ground roughness according to the modulus characteristics of the central sub - part on the outer - radial side of the tread band, and at the same time, since it is formed from a vulcanized elastomer material that achieves a high grip according to the modulus characteristics of the inner - radial part of the tread band, it is advantageously possible to optimize and substantially keep constant over a long period the handling and performance of the tire under high - speed driving conditions on a dry and / or hot surface during straight - line driving.

[0105] Preferably, the ratio R5 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the second vulcanized elastomer material of the lateral sub - part on the outer - radial side of the tread band to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material of the inner - radial part of the tread band is included between 1.1 and 1.6, more preferably between 1.2 and 1.5.

[0106] In this way, it is advantageously possible to achieve an excellent level of handling and performance of the tire under "low - temperature" use conditions, such as, for example, during the warm - up stage of the tire, or on wet ground and / or in low - temperature climatic conditions, or under very severe camber conditions on a curve of a non - optimal road surface.

[0107] Although not wishing to be bound by any theory of interpretation, the applicant believes that in this case, the third vulcanized elastomer material of the inner - radial part of the tread band enables appropriate deformation of the lateral or shoulder sub - part of the outer - radial part of the tread band, thereby increasing their contact area with the ground.

[0108] Preferably, the ratio R6 of the tanδ measured at a frequency of 10 Hz and 23 °C of the second vulcanized elastomer material of the lateral sub - part on the outer - radial side of the tread band to the tanδ measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material of the inner - radial part of the tread band is included between 1.1 and 1.6, more preferably between 1.2 and 1.5.

[0109] Preferably, the ratio R7 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the first vulcanized elastomer material in the central sub-part of the radially outer part of the tread band to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material in the radially inner part of the tread band is included between 1.2 and 1.8, more preferably between 1.3 and 1.7.

[0110] Preferably, the ratio R8 of the tanδ measured at a frequency of 10 Hz and 23 °C of the first vulcanized elastomer material in the central sub-part of the radially outer part of the tread band to the tanδ measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material in the radially inner part of the tread band is included between 0.6 and 1.1, preferably between 0.7 and 1.0.

[0111] In this way, it is advantageously possible to achieve an excellent level of handling and performance of the tire under "low temperature" usage conditions, for example, during the warm-up phase of the tire, or during straight-line driving on wet ground and / or in low-temperature climatic conditions, or on a non-optimal road surface.

[0112] Although not wishing to be bound by any theory of interpretation, the applicant believes that in this case, the third vulcanized elastomer material in the radially inner part of the tread band has a hysteresis that is substantially equal to or appropriately greater than the hysteresis of the first vulcanized elastomer material in the central sub-part of the radially outer part of the tread band, thereby enabling an appropriate thermal effect of the central sub-part that increases the aforementioned contact area.

[0113] Preferably, the ratio R9 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material in the radially inner part of the tread band to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C of the same vulcanized elastomer material is included between 1.2 and 2.0, more preferably between 1.4 and 1.9.

[0114] Advantageously, due to this preferred feature, the third vulcanized elastomeric material of the radially inner portion of the tread band can have an optimal "flexibility" of its deformation properties under "low temperature" and "high temperature" usage conditions, and this flexibility effectively contributes to achieving the following advantageous technical effects.

[0115] First, through the cooperation between the third vulcanized elastomeric material of the radially inner portion of the tread band and the second vulcanized elastomeric material of the lateral or shoulder sub - portion of the radially outer portion of the tread band, which have very close "high - temperature" dynamic elastic moduli, i.e., degrees of deformation (refer to the value of the aforementioned ratio R1), it contributes to improving and maintaining the handling and performance of the tire under "high - temperature" usage conditions.

[0116] Second, it contributes to maintaining an excellent level of handling and performance of the tire under "low - temperature" usage conditions, such as during the warm - up phase of the tire, or when used on wet ground and / or in low - temperature climatic conditions, or on non - optimal road surfaces. This is due to the cooperation between the third vulcanized elastomeric material of the radially inner portion of the tread band and the first vulcanized elastomeric material of the central sub - portion of the radially outer portion of the tread band, and these elastomeric materials have "low - temperature" dynamic elastic moduli, i.e., degrees of deformation that are substantially different from each other (refer to the value of the aforementioned ratio R7).

[0117] Under the "low - temperature" usage conditions of the tire, in fact, the third vulcanized elastomeric material of the radially inner portion of the tread band is much more deformable and has much greater hysteresis compared to the first vulcanized elastomeric material of the central sub - portion of the radially outer portion of the tread band, thereby promoting the heating of the tread band during the warm - up phase and contributing to improving the grip of the tire on wet surfaces and / or in low - temperature climatic conditions, or on non - optimal road surfaces at "low - temperature" operating temperatures.

[0118] Preferably, the ratio R10 of the tanδ of the third vulcanized elastomer material in the radially inner part of the tread band, measured at a frequency of 10 Hz and 23°C, to the tanδ of the same vulcanized elastomer material, measured at a frequency of 10 Hz and 70°C, is between 1.5 and 2.4, more preferably between 1.7 and 2.1.

[0119] Advantageously, also due to this preferred feature, the third vulcanized elastomer material in the radially inner part of the tread band can have an optimal "flexibility" of its hysteresis characteristics in the "low temperature" and "high temperature" usage states, and this flexibility effectively contributes to achieving the above-mentioned advantageous technical effects.

[0120] Preferably, this tire is a tire for a rear wheel of a motorcycle and has a cross-sectional curvature ratio of about 0.30 or more, preferably between 0.30 and 0.35.

[0121] Further features and advantages of the present invention will become more readily apparent from the following description of some preferred embodiments shown hereinafter for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0122] Such drawings are schematic and not to scale.

Brief Description of the Drawings

[0123]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0124] In the figure, reference numeral 1 indicates, as a whole, a tire for a motorcycle wheel according to a preferred embodiment of the present invention. This is preferably a tire intended to be used for the rear wheel of a motorcycle, for a large-displacement, for example 600 cc, supersport motorcycle.

[0125] The equatorial plane X-X and the axis of rotation (not shown) are defined for the tire 1. The circumferential direction (in FIG. 1, indicated by the arrow F facing the rotation direction of the tire 1), and the axial direction, indicated in FIG. 2 by the axis r perpendicular to the equatorial plane X-X, are also defined.

[0126] The tire 1 comprises a carcass structure 2 formed by at least one carcass layer 3 comprising a plurality of reinforcing elements (cords).

[0127] The carcass structure 2 is typically coated on its inner wall by a seal layer, a so-called "liner", which basically consists of an airtight layer of elastomeric material, and is configured to ensure the airtight seal of the tire itself when inflated.

[0128] The reinforcing elements included in the carcass layer 3 preferably include a fabric cord made of a fibrous material.

[0129] The fibrous material used for the manufacture of the cord can be made of natural or synthetic-derived fibers selected from among rayon, lyocell, polyester (e.g., PEN, PET, PVA), aromatic polyamides (e.g., aramids such as Twaron® and Kevlar®), either alone or in combination. More specifically, the fibrous material for making the cord is preferably selected from among polyester, rayon, lyocell, aromatic polyamides, or hybrid materials formed by two or more of the aforementioned materials.

[0130] The reinforcing elements included in at least one carcass layer 3 are preferably arranged radially, i.e., according to an angle included between 70° and 110°, more preferably between 80° and 100°, with respect to the circumferential direction.

[0131] At least one carcass layer 3 is shaped substantially according to a toroidal form and is engaged with at least one annular reinforcement structure by the peripheral edges 3a on both sides thereof.

[0132] In particular, the side edges 3a on both sides of at least one carcass layer 3 can be folded around the annular reinforcement structure, and each of the annular reinforcement structures comprises one or more metallic annular bead cores 4 and a tapered elastomeric filler 5 occupying a space defined between the carcass layer 3 and the corresponding folded side edge 3a of the carcass layer 3.

[0133] The region of the tire comprising the bead core 4 and the filler 5 forms a so-called bead 9, which is intended to fix the tire 1 to a corresponding mounting rim (not shown).

[0134] In an embodiment (not shown), at least one carcass layer 3 is made by joining together a plurality of pieces of an elastomeric material reinforced by the aforementioned cords and has side edges on both sides thereof associated with a particular annular reinforcement structure without being folded. The filler made of an elastomeric material can be arranged in an axially outer position with respect to the first annular insert. On the other hand, the second annular insert can be arranged in an axially outer position with respect to the end of the carcass layer. Finally, a further filler, which does not necessarily have to be in contact therewith, may optionally be provided in an axially outer position with respect to this second annular insert to complete the construction of the annular reinforcement structure.

[0135] A belt structure 6 comprising at least one belt layer 6a typically formed of a rubber-coated cord is applied circumferentially at a radially outer position over the carcass structure 2.

[0136] Preferably, layer 6a is made of cords arranged substantially parallel and in parallel to each other so as to form a plurality of loops. Such loops are oriented substantially circumferentially (typically at an angle between 0° and 5°), and such a direction is usually referred to as "zero degree" with respect to the laying direction relative to the circumferential direction of the tire.

[0137] Preferably, the "zero degree" layer 6a can comprise a single cord winding adjacent axially, or an axially adjacent winding of a rubber-coated fabric band comprising axially adjacent cords.

[0138] The cords of layer 6a are fabric or metal cords. Preferably, such cords are metal cords made of steel wire with a high carbon content, in other words, steel wire with a carbon content of at least 0.6 - 0.7%.

[0139] Preferably, such metal cords have high elongation (HE).

[0140] In order to improve the adhesion between the belt structure 6 and the carcass structure 2, an adhesive layer 7 made of an elastomeric material may be sandwiched between the two aforementioned structures.

[0141] In an embodiment not shown, the belt structure 6 can be composed of at least two radially overlapping layers. The cords of the first belt layer are oriented obliquely with respect to the circumferential direction of the tire, and the cords of the second layer are also oriented obliquely, but are arranged so as to cross substantially symmetrically with respect to the cords of the first layer.

[0142] The tread band 8 is circumferentially superimposed on the belt structure 6, and after the molding operation performed simultaneously with the vulcanization of the tire, typically, longitudinal and / or transverse grooves are formed in the tread band 8 so as to define a desired tread pattern.

[0143] FIG. 1 shows, by way of non-limiting example, a tread pattern with a plurality of grooves arranged variously on both sides of the equatorial plane X-X of the tire 1.

[0144] Preferably, the tread pattern includes a substantially L-shaped first circumferential continuous groove 13, a second circumferential continuous groove 14 located axially outside the groove 13, and a group 15a, 15b, 15c, and 15d of third circumferential continuous grooves that are variously inclined with respect to the equatorial plane X-X of the tire 1 and are circumferentially sandwiched between the grooves 13.

[0145] For the sake of simplicity, such grooves are not shown in FIG. 2.

[0146] The tire 1 can include a pair of sidewalls 10 applied laterally on both sides of the carcass structure 2.

[0147] The tire 1 has a cross-sectional height H measured at the equatorial plane X-X between the top of the tread band 8 and the mounting diameter specified by the reference line r passing through the bead of the tire 1.

[0148] The tire 1 also has a maximum width C of the transverse cross-section defined by the distance between the axial ends E of the profile of the tread band 8, and a curvature ratio defined as the ratio of the distance f from the top of the tread band 8 to the line passing through both ends E of the tread band 8 itself measured at the equatorial plane of the tire 1 to the aforementioned maximum width C. The axial ends E of the tread band 8 can be formed at the ends.

[0149] In particular, the tire 1 has a transverse cross-section characterized by a large curvature ratio, preferably a curvature ratio f / C of at least about 0.30.

[0150] In a preferred embodiment, the motorcycle tire 1 of the present invention is intended to be mounted on a rear wheel having a cord size substantially included between 160 and 210 mm.

[0151] Preferably, the distance f between the radially outermost point of the tread band 8 and the line passing through the axially opposite ends E of the tread band 8 of the tire 1 itself is substantially included between 50 and 70 mm.

[0152] Preferably, for a tire 1 intended to be mounted on the rear wheel of a motorcycle, the transverse curvature ratio f / C is substantially about 0.30 or more, more preferably included between 0.30 and 0.35.

[0153] Preferably, the overall height / cord ratio H / C is substantially included between 0.5 and 0.65.

[0154] In a preferred embodiment, for example, when the tire 1 is intended to be mounted on the rear wheel of a motorcycle, better performance can be achieved when the tire 1 has a sidewall 10 of substantial height such that the value of the sidewall height ratio (H - f) / H is 0.35 or more, more preferably 0.4 or more.

[0155] Preferably, the ratio of the shoulder radius to the maximum cross-sectional width of the tire 1 is 0.60 or more.

[0156] According to the present invention, the tread band 8 is of the so-called "cap and base" type and is made of at least three different elastomeric materials.

[0157] In the illustrated preferred embodiment, the tread band 8 a1) a central sub-part 11a arranged across the equatorial plane X-X of the tire 1 and made of a first vulcanized elastomeric material, and a2) a pair of lateral sub-parts 11b, 11c distal to the equatorial plane X-X of the tire 1 and arranged on both sides of the central sub-part 11a comprises a radially outer part 11.

[0158] As outlined above, the lateral sub-parts 11b, 11c of the tread band 8 are made of a second vulcanized elastomeric material.

[0159] In the illustrated preferred embodiment, the tread band 8 comprises a radially inner portion 12 that extends along the entire axial development of the tread band 8 below the radially outer portion 11 of the tread band 8.

[0160] As outlined above, the radially inner portion 12 of the tread band 8 is made of a third vulcanized elastomeric material.

[0161] Preferably, the central annular sub-portion 11a of the tread band 8 has an axial development L1 that extends in the transverse direction over 25% to 40%, more preferably 30% to 35% of the entire axial development L of the tread band 8.

[0162] Preferably, the lateral sub-portions 11b, 11c of the tread band 8 each have an axial development L2, L3 that extends in the transverse direction over 25% to 40%, more preferably 30% to 35% of the entire axial development L of the tread band 8.

[0163] The central sub-portion 11a of the radially outer portion 11 of the tread band 8 is advantageously formed integrally by arranging, for example, a helix of at least one continuous elongate element of the aforementioned first vulcanized elastomeric material adjacent thereto in the circumferential direction.

[0164] Conversely, the lateral sub-portions 11b, 11c of the tread band 8 are advantageously formed integrally by arranging, for example, a ring of at least one continuous elongate element of the aforementioned second vulcanized elastomeric material adjacent thereto in the circumferential direction.

[0165] Thus, and as outlined above, in the radially outer portion 11 of the tread band 8, a pair of boundary surfaces 16 between the first vulcanized elastomeric material and the second vulcanized elastomeric material are defined on both sides of the central annular portion 11a on both sides of the equatorial plane X-X of the tire 1.

[0166] Thus, in this preferred configuration of the tread band 8, the interface surface 16 separates the central sub - portion 11a of the radially outer portion 11 of the tread band 8 from the lateral sub - portions 11b, 11c along the axial direction.

[0167] Preferably, the lateral sub - portions 11b, 11c of the radially outer portion 11 of the tread band 8, and thus the interface surface 16, are arranged at a distance from the equatorial plane X - X of the tire 1 that is between 25% and 40%, more preferably between 30% and 35% of half of the axial development L / 2 of the tread band, as defined above.

[0168] In the preferred embodiment shown in FIG. 2, the interface surface 16 can converge from the inside to the outside of the tread band 8 towards the equatorial plane X - X of the tire 1, and the interface surface is oriented along a direction inclined with respect to the equatorial plane X - X at an angle included between 30° and 50°, preferably between 35° and 40°.

[0169] In this preferred configuration of the tread band 8, the radially inner portion 12 of the tread band 8 extends substantially over the entire axial development of the belt structure 6.

[0170] Thus, in this preferred configuration of the tread band 8, the radially inner portion 12 of the tread band 8 is radially sandwiched between the belt structure 6 and the central sub - portion 11a and the lateral sub - portions 11b, 11c of the radially outer portion 11 of the tread band 8.

[0171] The rubber compounds of the different parts of the tread band 8 contain at least one elastomeric polymer (a1), like the rubber compounds of the other semi - finished products forming the tire 1.

[0172] Advantageously, such rubber compounds contain at least one α - olefin and have a specific formulation as described in more detail below.

[0173] According to one embodiment, this at least one elastomeric gum polymer (a1) can be selected from elastomeric gum polymers generally used in sulfur-crosslinkable (vulcanizable) elastomeric compositions, which are particularly suitable for the manufacture of tires, i.e., usually elastomeric polymers or copolymers having unsaturated chains with a glass transition temperature (Tg) lower than 20 °C, preferably in the range of 0 °C to -110 °C. These polymers or copolymers may be of natural origin or, optionally, may be obtained by solution polymerization, emulsion polymerization, or gas-phase polymerization of one or more conjugated diolefins mixed with at least one comonomer selected from monovinyl arenes and / or polar comonomers.

[0174] Preferably, for the tread rubber compound, polybutadiene (BR) and / or styrene-butadiene polymer (SBR), such as SSBR (solution-polymerized styrene-butadiene elastomer) or E-SBR (emulsion-polymerized styrene-butadiene elastomer), may be used alone or in combination.

[0175] Preferably, the styrene-butadiene polymer (SBR) can be present in the rubber compound of the present invention in a variable amount of about 50 to 100 phr, more preferably 70 to 100 phr.

[0176] Advantageously, polybutadiene (BR) can be included in the rubber compound of the present invention, particularly in the tread rubber compound, in an amount of not present or about 0 phr to 40 phr, more preferably about 10 to 30 phr.

[0177] Preferably, the styrene-butadiene polymer can be obtained from a solution or emulsion and generally contains styrene in an amount of about 10 to 40% by weight, preferably about 15 to 30% by weight.

[0178] Preferably, the styrene-butadiene polymer can have a low molecular weight and has an average molecular weight Mn of less than 200,000 g / mol, preferably between 150,000 and 200,000 g / mol.

[0179] The elastomeric material of the different parts of the tread band 8 contains at least one reinforcing filler present in an amount generally included between 1 phr and 130 phr.

[0180] Such reinforcing fillers are preferably selected from carbon black and so-called white fillers, namely silica, alumina, silicate, hydrotalcite, calcium carbonate, kaolin, titanium dioxide, and mixtures thereof.

[0181] The reinforcing fillers used in the elastomeric material of the different parts of the tread band 8 can include only carbon black or both carbon black and one or more white fillers, such as silica.

[0182] In a preferred embodiment, the first vulcanized elastomeric material of the central sub-part 11a of the radially outer part 11 of the tread band 8 contains more than 75% by weight, preferably 80% by weight or more, more preferably 85% by weight or more, more preferably 90% by weight or more, more preferably more than 95% by weight of the total weight of the reinforcing filler for the "white" reinforcing filler as defined above.

[0183] More preferably, such a "white" reinforcing filler is selected from silica, alumina, silicate, hydrotalcite, calcium carbonate, kaolin, titanium dioxide, and mixtures thereof.

[0184] Even more preferably, the "white" reinforcing filler is 50 m 2 / g to 500 m 2 / g, preferably 70 m 2 / g to 200 m 2It can be pyrolysis silica or precipitated silica having a BET surface area (measured according to ISO standard 5794 / 1) included between / g.

[0185] In this way, it is advantageously possible to achieve rapid warm-up of the tread band 11 of the tire 1 and excellent grip under different road surface conditions.

[0186] In a preferred embodiment, the second elastomeric material of the lateral sub-portions 11b, 11c of the radially outer portion 11 of the tread band 8 contains, for carbon black, more than 75% by weight, preferably 80% by weight or more, more preferably 85% by weight or more, more preferably 90% by weight or more, more preferably more than 95% by weight of the total weight of the reinforcing filler.

[0187] Preferably, the carbon black is not less than 20 m 2 / g, preferably more than 50 m 2 / g and is selected from those having a surface area (determined by STSA - statistical thickness surface area according to ISO 18852:2005).

[0188] The carbon black can be, for example, N234, N326, N330, N375, N550, or N660 sold by Birla Group (India), or CRX 1391 of Cabot Corporation.

[0189] The reinforcing filler can include, for example, a mixture of carbon black and silica.

[0190] In this way, it is advantageously possible to achieve optimal support during cornering and optimal traction during acceleration in order to manage the torque generated by a high-performance motorcycle such as, for example, a previous-generation superbike.

[0191] The above elastomer composition and the elastomer composition of other components of the tire 1 can be vulcanized using known techniques, in particular, using a sulfur-based vulcanization system commonly used for elastomer polymers. For this purpose, in the elastomer composition, after one or more thermomechanical treatment steps, a sulfur-based vulcanizing agent is compounded together with a vulcanization accelerator. In the final stage of this treatment, the temperature is generally kept below 140 °C to avoid undesirable pre-vulcanization phenomena.

[0192] The most advantageously used vulcanizing agent is sulfur or a sulfur-containing molecule (sulfur donor), and the accelerators and activators are known to those skilled in the art.

[0193] Particularly effective activators are zinc-based compounds, especially ZnO, ZnCO 3 , zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms, for example, preferably zinc stearate formed in situ in the elastomer composition from ZnO and fatty acids, and also BiO, PbO, Pb 3 O 4 , PbO 2 , or mixtures thereof, etc.

[0194] Generally used accelerators can be selected from dithiocarbamates, guanidines, thioureas, thiazoles, sulfonamides, thiurams, amines, xanthates, or mixtures thereof.

[0195] The elastomer compositions used can include other additives generally selected based on the specific use for which each composition is intended.

[0196] For example, antioxidants, anti-aging agents, plasticizers, adhesives, anti-ozone agents, modified resins, fibers (aramid or natural-derived fibers), or mixtures thereof can be added to these elastomer compositions.

[0197] In Table 1 below, there is shown merely an example for indicating rubber compounds which become the first, second, and third vulcanized elastomer materials in a preferred embodiment of Tire 1 after vulcanization.

[0198] The amounts of the various components of the elastomer composition are generally expressed in phr as defined above.

[0199]

Table 1

[0200] According to the present invention, the first vulcanized elastomer material of the central sub-part 11a of the radially outer part 11 of the tread band 8 has a dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C, which is greater than that of the second vulcanized elastomer materials of the lateral sub-parts 11b, 11c.

[0201] Furthermore, the first vulcanized elastomer material of the central sub - portion 11a of the radially outer portion 11 of the tread band 8 and the second vulcanized elastomer materials of the lateral sub - portions 11b, 11c each have a dynamic elastic modulus E' measured at a frequency of 10 Hz and 23 °C, which is included between 5.2 and 6.5 MPa, preferably between 5.8 and 6.4 MPa.

[0202] Furthermore, according to the present invention, the third vulcanized elastomer material of the radially inner portion 12 of the tread band 8 has a dynamic elastic modulus E' measured at a frequency of 10 Hz and 23 °C, which is lower than the dynamic elastic modulus E' measured at a frequency of 10 Hz and 23 °C of the first vulcanized elastomer material of the central sub - portion 11a of the radially outer portion 11 of the tread band 8 and the second vulcanized elastomer materials of the lateral sub - portions 11b, 11c.

[0203] As outlined above, the applicant believes that under the "low - temperature" use conditions of the tire 1, the third vulcanized elastomer material present in the radially inner portion 12 of the tread band 8 undergoes deformation (correlated with the elastic modulus E') and hysteresis phenomena (correlated with the tanδ parameter) in the lateral or shoulder portions of the tire, thereby being able to "heat" the radially outer portion 11 of the tread band 8 above it (which is harder and has less hysteresis), so that the radially outer portion 11 can adhere better to the wet and / or low - temperature ground.

[0204] According to the present invention, the ratio R1 between the dynamic elastic modulus E' measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer materials of the lateral sub - portions 11b, 11c of the radially outer portion 11 of the tread band 8 and the dynamic elastic modulus E' measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion 12 of the tread band 8 is included between 0.8 and 1.2, preferably between 0.9 and 1.1.

[0205] Furthermore, the ratio R2 of the tanδ measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer material of the lateral sub-portions 11b, 11c of the radially outer portion 11 of the tread band 8 to the tanδ measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion 12 of the tread band 8 is included between 0.8 and 1.2, preferably between 0.9 and 1.1.

[0206] As outlined above, the Applicant has experimentally observed that by controlling the aforementioned ratio R1 between the deformation characteristics correlated with the value of the dynamic elastic modulus E’ and the aforementioned ratio R2 between the hysteresis characteristics correlated with the tanδ value to be close to 1, it is advantageously possible to have optimal dynamic behavior and hysteresis behavior in the "high temperature" usage conditions of the tire, limit the phenomena of premature wear and performance degradation in the shoulder region, and ensure optimal running performance on a straight course in the central region.

[0207] The tire 1 can also comprise one or more of the above-preferred features that achieve corresponding advantageous technical effects.

[0208] Next, the present invention will be described by way of several examples, which are for illustrative purposes and not for the purpose of limitation.

[0209] Properties of the vulcanized elastomer composition In Table 2 below, there is shown a mere example for showing the rubber compounds that become the first, second, and third vulcanized elastomer materials in a particularly preferred embodiment of the tire 1 after vulcanization.

[0210] The amounts of the various components of the elastomer composition are generally indicated in phr as defined above.

[0211]

Table 2

[0212] Table 3 below shows the results of static and dynamic mechanical analyses performed on specimens of the compositions used in the three materials of the radially inner part 12 and the radially outer part 11 of the tread band 8 of tire 1 according to the present invention, the formulation of which is shown in Table 1 above.

[0213] These analyses were carried out according to the techniques shown above, under temperature and frequency conditions.

[0214]

Table 3

[0215] Table 4 below shows the ratios of the dynamic mechanical properties of the elastic modulus E' and tanδ in each of the vulcanized elastomer materials which are the subject of the present invention, for various vulcanized elastomer materials.

[0216]

Table 4

[0217] From Table 4, it is clearly understood that the values of the ratios R1, R2, R5, and R6 equal to or close to 1 predict homogeneous behavior both at “high temperature” and at “low temperature” between the second vulcanized elastomer material and the third vulcanized elastomer material, that is, between the rubber compound present in the radially outer part of the shoulder region of Tire 1 and the rubber compound present in the radially inner part.

[0218] Also from Table 4, the “high temperature” values of the ratios R3 and R4 of tanδ and dynamic elastic modulus E’ between the first vulcanized elastomer material present in the central sub - part of the radially outer part of the tread band of Tire 1 and the third vulcanized elastomer material present in the radially inner part predict an appropriately differentiated behavior between such materials, that is, a more deformable and highly hysteretic behavior in the base part of the tread band and a more rigid and less hysteretic behavior in the central sub - part of the radially outer part of the tread band.

[0219] In this way, as outlined above, such vulcanized elastomer materials can achieve the optimal “high temperature” handling performance and load - holding performance of the tire when driving on a straight course.

[0220] Finally, from Table 4, the “low temperature” values of the ratios R7 and R8 of dynamic elastic modulus E’ and tanδ between the first vulcanized elastomer material present in the central sub - part of the radially outer part of Tire 1 and the third vulcanized elastomer material present in the radially inner part predict an appropriately differentiated behavior between such materials, that is, a more deformable and highly hysteretic behavior in the base part of the tread band and a more rigid and less hysteretic behavior in the central part of the radially outer part of the tread band.

[0221] In this way, as outlined above, such a vulcanized elastomer material can achieve the optimal "low-temperature" handling performance and load holding performance of the tire during straight-course driving.

[0222] Outdoor tire test In order to obtain improved performance, the applicant has found that it has received high evaluations from sports users and has now chosen the Pirelli Diablo Rosso (trademark) IV 190 / 55ZR17, which is still a benchmark tire, as the basis for a comparative driving test for the rear wheel.

[0223] In sports driving, the rear tire has a greater thermal load than the front tire, so the choice to conduct the test on the rear tire was considered particularly stringent.

[0224] Both the tire according to the present invention and the comparative tire have a "cap and base" structure of the tread band. However, the comparative tire is different in that it has a structure with two different vulcanized elastomer materials, namely, a first elastomer material in the lateral sub-part of the radially outer part of the tread band and a second elastomer material in the central sub-part and the radially inner part of the radially outer part of the tread band.

[0225] As shown above with reference to FIG. 2, the tire according to the present invention has a structure having three different vulcanized elastomer materials, two on the radially outer side and one on the radially inner side.

[0226] Using the rubber compound shown in Table 2 having the mechanical properties shown in Tables 3 and 4, the radially inner part and the radially outer part of the tread band of a super sports tire for the rear wheel of a size similar to that of the comparative tire were produced.

[0227] The tread band of the cap-and-base type comparison tire was manufactured using the two materials shown in Table 5 below (for those applicable, the components shown in Table 2 above).

[0228]

Table 5

[0229] To test grip and maneuverability on both dry and wet ground, various test sessions were conducted on a private race track by performing a series of operations. The driver's evaluation is the average of the evaluations in various operations.

[0230] In the dry ground test, the conditions were as follows. Tire air pressure: 2.5 bar, track asphalt temperature: 39°C, air temperature: 18°C.

[0231] In the wet ground test, the conditions were as follows. Tire air pressure: 2.9 bar, track asphalt temperature: 8°C, air temperature: 8°C.

[0232] The test was conducted on the "Super Sports" motorcycle model BMW (registered trademark) S1000R.

[0233] Tables 6 and 7 below summarize the scores given by the test operators for various types of required performance of the tires being tested on dry and wet ground, respectively.

[0234] Furthermore, in the dry ground test, different sets of the tire according to the present invention and the comparison tire were tested both for one lap of the track (columns 1 and 2 of Table 6) and for 20 laps completed (columns 3 and 4 of Table 6). In this second case, performance degradation due to high-load use ("hard handling") simulating a race on the track or several training sessions (about 100 km of driving) was confirmed.

[0235] Table 5 shows the evaluation of the tire according to the present invention having the same performance as the comparative tire by the symbol "=", and shows the evaluation of improvement for the comparative tire by a larger number of symbols "+" as the improvement in performance increases.

[0236] It should be noted that there is homogeneity in the evaluation only between column 1 and column 2 (one revolution), and only between column 3 and column 4 (after 20 revolutions of running). In other words, the evaluation of one revolution was performed with a different set of tires from the set of tires in the race simulation test, and such one revolution is not the first lap of the race simulation.

[0237]

Table 6

[0238]

Table 7

[0239] From the evaluations shown in Table 6 and Table 7, it is clearly understood that the tire according to the present invention achieved the two desired objectives of improving the handling performance and the tire performance under "high temperature" use conditions without sacrificing the handling and load holding performance of the tire under the aforementioned "low temperature" use conditions, and maintaining them as constant as possible over a long period of time.

[0240] Surprisingly, even though a "soft" vulcanized elastomer material that is clearly not very suitable for this type of running condition is used in the radially inner part of the tread band, the effect of improving and maintaining the handling and performance of the tire under "high temperature" use conditions has been achieved.

[0241] During the implementation of the test, it was also noticed that the lap time on the test circuit was significantly shortened for the tire according to the present invention.

[0242] Various changes can be made to the detailed embodiments as long as they remain within the scope of protection of the present invention defined by the following claims.

Claims

1. A motorcycle tire (1) comprising an equatorial plane (X-X) and a tread band (8), wherein the tread band (8) has a) a radially outer portion (11) having a1) a central sub-portion (11a) arranged across the equatorial plane (X-X) of the tire and made of a first vulcanized elastomer material; and a2) a pair of lateral sub-portions (11b, 11c) distal to the equatorial plane (X-X) of the tire (1) and arranged on both sides of the central sub-portion (11a), the pair of lateral sub-portions (11b, 11c) being made of a second vulcanized elastomer material; the first vulcanized elastomer material of the central sub-portion (11a) has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is greater than the dynamic elastic modulus (E') of the second vulcanized elastomer material of the lateral sub-portions (11b, 11c); the first vulcanized elastomer material of the central sub-portion (11a) and the second vulcanized elastomer material of the lateral sub-portions (11b, 11c) each have a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is included between 5.2 and 6.5 MPa, preferably between 5.8 and 6.4 MPa, the radially outer portion (11); b) a radially inner portion (12) extending along the entire axial development of the tread band (8) below the radially outer portion (11) of the tread band (8), the radially inner portion (12) being made of a third vulcanized elastomer material having a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is lower than the dynamic elastic modulus (E') of the first vulcanized elastomer material of the central sub-portion (11a) of the radially outer portion (11) of the tread band (8) and the dynamic elastic modulus (E') of the second vulcanized elastomer material of the lateral sub-portions (11b, 11c) of the radially outer portion (11) of the tread band (8); The ratio R1 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer material of the lateral sub - portions (11b, 11c) of the radially outer portion (11) of the tread band (8) to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) is included between 0.8 and 1.2, preferably between 0.9 and 1.

1. The ratio R2 of the tanδ measured at a frequency of 10 Hz and 100 °C of the second vulcanized elastomer material of the lateral sub - portions (11b, 11c) of the radially outer portion (11) of the tread band (8) to the tanδ measured at a frequency of 10 Hz and 70 °C of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) is included between 0.8 and 1.2, preferably between 0.9 and 1.

1. A motorcycle tire (1). **Claim 2** The first vulcanized elastomer material of the central sub - portion (11a) 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 70 °C, which is included between 5.1 and 5.5 MPa, preferably between 5.2 and 5.4 MPa. The motorcycle tire (1) according to claim 1. **Claim 3** The first vulcanized elastomer material of the central sub - portion (11a) of the radially outer portion (11) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 70 °C, which is included between 0.26 and 0.30, preferably between 0.27 and 0.

29. The motorcycle tire (1) according to claim 1 or 2. **Claim 4** The second vulcanized elastomer material of the lateral sub - portions (11b, 11c) 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 100 °C, which is included between 2.5 and 2.9 MPa, preferably between 2.6 and 2.8 MPa. The motorcycle tire (1) according to any one of claims 1 - 3. **Claim 5** The second vulcanized elastomer material of the lateral sub-portions (11b, 11c) of the radially outer portion (11) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 100 °C and is included between 0.24 and 0.28, preferably between 0.25 and 0.

27. The motorcycle tire (1) according to any one of claims 1 to 4.

6. The third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70 °C and is included between 2.5 and 2.9 MPa, preferably between 2.6 and 2.8 MPa. The motorcycle tire (1) according to any one of claims 1 to 5.

7. The third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 70 °C and is included between 0.25 and 0.29 MPa, preferably between 0.26 and 0.28 MPa. The motorcycle tire (1) according to any one of claims 1 to 6.

8. The first vulcanized elastomer material of the central sub-portion (11a) of the radially outer portion (11) of the tread band (23) has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C and is included between 6.0 and 6.5 MPa, preferably between 6.2 and 6.4 MPa. The motorcycle tire (1) according to any one of claims 1 to 7.

9. The first vulcanized elastomer material of the central sub-portion (11a) of the radially outer portion (11) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 23 °C and is included between 0.40 and 0.44, preferably between 0.41 and 0.

43. The motorcycle tire (1) according to any one of claims 1 to 8.

10. The second vulcanized elastomer material of the lateral sub-portions (11b, 11c) 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 is included between 5.5 and 6.0 MPa, preferably between 5.7 and 5.9 MPa. The motorcycle tire (1) according to any one of claims 1 to 9.

11. The second vulcanized elastomer material of the lateral sub - portions (11b, 11c) of the radially outer portion (11) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 23°C, which is included between 0.66 and 0.70, preferably between 0.67 and 0.

69. The motorcycle tire (1) according to any one of claims 1 to 10.

12. The third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C, which is included between 4.0 and 5.0 MPa, preferably between 4.2 and 4.5 MPa. The motorcycle tire (1) according to any one of claims 1 to 11.

13. The third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) has a tanδ measured at a frequency of 10 Hz and 23°C, which is included between 0.49 and 0.53 MPa, preferably between 0.50 and 0.52 MPa. The motorcycle tire (1) according to any one of claims 1 to 12.

14. The ratio R3 of the tanδ of the first vulcanized elastomer material of the central sub - portion (11a) of the radially outer portion (11) of the tread band (8) measured at a frequency of 10 Hz and 70°C to the tanδ of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) measured at a frequency of 10 Hz and 70°C is included between 0.5 and 1.2, preferably between 0.7 and 1.

0. The motorcycle tire (1) according to any one of claims 1 to 13.

15. The ratio R4 of the dynamic elastic modulus (E') of the first vulcanized elastomer material of the central sub - portion (11a) of the radially outer portion (11) of the tread band (8) measured at a frequency of 10 Hz and 70°C to the dynamic elastic modulus (E') of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) measured at a frequency of 10 Hz and 70°C is included between 1.3 and 2.0, preferably between 1.5 and 1.

8. The motorcycle tire (1) according to any one of claims 1 to 14.

16. The ratio R5 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the second vulcanized elastomer material of the lateral sub-portions (11b, 11c) of the radially outer portion (11) of the tread band (8) to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) is included between 1.1 and 1.6, preferably between 1.2 and 1.5, for the motorcycle tire (1) according to any one of claims 1 to 15.

17. The ratio R6 of the tanδ measured at a frequency of 10 Hz and 23 °C of the second vulcanized elastomer material of the lateral sub-portions (11b, 11c) of the radially outer portion (11) of the tread band (8) to the tanδ measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) is included between 1.1 and 1.6, preferably between 1.2 and 1.5, for the motorcycle tire (1) according to any one of claims 1 to 16.

18. The ratio R7 of the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the first vulcanized elastomer material of the central sub-portion (11a) of the radially outer portion (11) of the tread band (8) to the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) is included between 1.2 and 1.8, preferably between 1.3 and 1.7, for the motorcycle tire (1) according to any one of claims 1 to 17.

19. The ratio R8 of the tanδ measured at a frequency of 10 Hz and 23 °C of the first vulcanized elastomer material of the central sub-portion (11a) of the radially outer portion (11) of the tread band (8) to the tanδ measured at a frequency of 10 Hz and 23 °C of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8) is included between 0.6 and 1.1, preferably between 0.7 and 1.0, for the motorcycle tire (1) according to any one of claims 1 to 18.

20. For the tire (1) for a motorcycle according to any one of claims 1 to 19, the ratio R9 of the dynamic elastic modulus (E') of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8), measured at a frequency of 10 Hz and 23°C, to the dynamic elastic modulus (E') of the same vulcanized elastomer material, measured at a frequency of 10 Hz and 70°C, is included between 1.2 and 2.0, preferably between 1.4 and 1.

9.

21. For the tire (1) for a motorcycle according to any one of claims 1 to 20, the ratio R10 of tanδ of the third vulcanized elastomer material of the radially inner portion (12) of the tread band (8), measured at a frequency of 10 Hz and 23°C, to tanδ of the same vulcanized elastomer material, measured at a frequency of 10 Hz and 70°C, is included between 1.5 and 2.4, preferably between 1.7 and 2.

1.

22. The tire (1) for a motorcycle according to any one of claims 1 to 21, having a cross-sectional direction curvature ratio of about 0.30 or more, preferably included between 0.30 and 0.35.

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