Motorcycle tire

Abstract

Described is a tyre (1) for motorcycle wheels, comprising a tread band (8) of the "crown base" type comprising: a radially outer portion formed by a central sub-portion (11a) made of a first vulcanized elastomeric material and a pair of lateral sub-portions (11b, 11c) made of a second vulcanized elastomeric material; and a radially inner portion (12) made of a third vulcanized elastomeric material. The dynamic elastic modulus (E ') of the first vulcanized elastomeric material of the central sub-portion (11a) measured at a frequency of 10 Hz and 23 DEG C is greater than the dynamic elastic modulus (E') of the second vulcanized elastomeric material of the lateral sub-portions (11b, 11c) measured under the same conditions, and the respective dynamic elastic modulus (E ') of these two vulcanized elastomeric materials measured at the same frequency of 10 Hz and 23 DEG C is between 5.2 MPa and 6.5 MPa and greater than the dynamic elastic modulus (E') of the third vulcanized elastomeric material measured under the same conditions. In the tyre (1), the ratio R1 and R2 between the dynamic elastic modulus and tan delta of the second vulcanized elastomeric material of the lateral sub-portions (11b, 11c) of the radially outer portion of the tread band (8) measured at a frequency of 10 Hz and 100 DEG C and the dynamic elastic modulus and tan delta of the third vulcanized elastomeric material of the radially inner portion (12) measured at a frequency of 10 Hz and 70 DEG C is between 0.8 and 1.2.

Description

Technical Field

[0001] The invention relates to a motorcycle tire.

[0002] In particular, the present invention relates to a method for a pump having a large displacement (e.g., 600 cm 3 or 1000cm 3 Motorcycle tires for "supersport" and / or "ultrasport" type motorcycles having 200 horsepower or more and / or high power (e.g., 200 horsepower or more), which are also used on racetracks.

[0003] More particularly, 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 withstanding a maximum load of at least about 210 kg or both. Background Art

[0004] Motorcycle tires are known, for example, from EP 2 662 226 A1 and WO 2019 / 082012. Summary of the invention

[0005] Recently, a trend has been observed towards the introduction of high-powered motorcycles for supersport or ultra-sport purposes. Indeed, there are motorcycles with a displacement of 1000 cm 3 And larger road motorcycles with 200 horsepower or more.

[0006] The applicant has noticed that there is a growing demand for such super sports motorcycles, both on the road and on the track.

[0007] At the same time, the Applicant has noticed a growing demand for high-performance tires suitable for demanding sports driving (e.g. performed on racetracks) as well as for service life and handling in any atmospheric and seasonal conditions (motorcycles suitable for year-round use on roads).

[0008] In this regard, the Applicant has taken particular note of recent trends whereby users desire tyres for installation on super sports motorcycles that have both handling and performance under extreme speed and handling conditions on dry and / or hot surfaces (hereinafter also referred to as "hot" use conditions) as well as handling and grip under wet and / or cold climatic conditions or on non-optimal road conditions (hereinafter also referred to as "cold" use conditions), and that keep tyre performance as stable as possible over time.

[0009] Meeting these conflicting requirements with a single pair of tires is a particularly difficult task, as each of these requirements usually requires a different intervention, with solutions that are appropriate for certain problems but conflict with others.

[0010] In order to improve handling and performance on dry and / or hot surfaces as well as in wet and / or cold climatic conditions or on non-optimal road surfaces, it is particularly desirable to ensure optimal grip in these different driving conditions.

[0011] In order to improve the grip of the tire, so-called soft vulcanized elastomeric materials (also defined herein as "rubber compounds") can be used when manufacturing the tread band, which can better adapt to the roughness of the road surface by imitating the irregular contours of the road surface. These vulcanized elastomeric materials are generally characterized by a low elastic modulus and / or a high hysteresis.

[0012] However, the applicant has found that a rubber compound that is too soft can lead to reduced driving stability when traveling in a straight line and can shorten the life of the tire.

[0013] In order to overcome the above problems, tires with tread bands made of different rubber compounds have been proposed. Typically, the rubber compound at the shoulder is softer, while the rubber compound at the crown is not so soft.

[0014] A tyre configured in this way is described, for example, in EP 2 662 226 .

[0015] However, with regard to this configuration of tread band, the Applicant has observed that the handling and performance of the tyre in “hot” conditions of use tend to deteriorate, particularly in cases of extreme use (such as, for example, on racetracks), with serious detriment to the useful life of the tyre.

[0016] In order to try to meet the aforementioned contradictory requirements with a single pair of tires, tires have also been proposed whose tread bands are made of different rubber compounds, generally using a rubber compound with a higher content of carbon black filler in the shoulder parts, and several rubber compounds with a higher content of white filler in the crown and in the middle annular part of the tread band, all of which are combined with a proper distribution and positioning of the grooves of the tread band at the interfaces between the rubber compounds of different compositions, for example, as described in the applicant's patent application WO 2019 / 082012.

[0017] Finally, the Applicant notes that a rigid tyre structure (typical for racetracks) does not seem to be well suited for road use, where the tyres are deflated to a pressure a few tenths of a bar lower than the pressure recommended by the manufacturer in order to have a larger ground contact area and thus be fully prepared for extreme handling, whereas on roads the tyres need to be inflated to the pressure recommended by the manufacturer in order to provide comfort, grip and the ability to absorb stress on different road surfaces.

[0018] In the ongoing quest for improvements in motorcycle tires, the applicant has set a dual objective: to improve and maintain as long as possible the handling and tire performance under "hot" use conditions, without impairing the handling and road holding properties of the tire under the aforementioned "cold" use conditions.

[0019] The Applicant has discovered that this dual purpose can be achieved by adopting a so-called "cap-base" tread band construction and by using a vulcanized elastomeric material having suitable dynamic mechanical properties both under "cold" and "hot" conditions of use of the tire.

[0020] In particular, the applicant finds that, for this purpose, the following provisions must be adopted simultaneously:

[0021] i) using a configuration of the radially outer portion of the tread band of the type comprising a central sub-portion arranged astride the equatorial plane of the tyre and a pair of lateral sub-portions distally with respect to the equatorial plane of the tyre and arranged on opposite sides of said central sub-portion; and

[0022] ii) Use in each portion of the tread band a vulcanized elastomeric material having specific dynamic mechanical properties both under the respective "hot" and "cold" conditions of use of the tyre.

[0023] In this regard, the Applicant has also found that it is necessary to carry out a differentiated assessment of the dynamic mechanical properties of the vulcanized elastomeric materials used to manufacture the different parts of the tread band, for each elastomeric material and under specific stress and temperature conditions that can be linked to the actual use conditions of each material, each material being subjected to different types of stresses and different temperatures during the use of the tire, depending on the position of the material in the tread band.

[0024] As far as "cold" use of the tyre is concerned, the Applicant has found in particular that the dynamic mechanical properties predictive of the behaviour of the tyre under such use conditions are the dynamic elastic modulus E' and tan δ measured at a frequency of 10 Hz and 23°C for all the elastomeric materials forming the tread band.

[0025] Conversely, as far as "hot" use of the tire is concerned, the Applicant has found that the dynamic mechanical properties that predict the behavior of the tire under such conditions of use are the dynamic elastic modulus E' and tan δ, measured respectively at:

[0026] - measurements are carried out at a frequency of 10 Hz and at 70° C. on the vulcanized elastomeric material of a central sub-portion of the radially outer portion of the tread band and on the vulcanized elastomeric material of the radially inner portion of the tread band; and

[0027] - Measurements are carried out at a frequency of 10 Hz and at 100° C. on the vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band.

[0028] Therefore, the applicant has found that it is possible to maintain the handling and grip performance of the tire under the above-mentioned "cold" use conditions by using the following materials:

[0029] - in a central sub-portion of the radially outer portion of the tread band, use is made of a first vulcanized elastomeric material having a dynamic modulus of elasticity E' measured at a frequency of 10 Hz and at 23°C greater than the dynamic modulus of elasticity E' of a second vulcanized elastomeric material used in the lateral sub-portions of the radially outer portion of the tread band, and

[0030] - In the radially inner portion of the tread band, a third vulcanized elastomeric material is used, the dynamic elastic modulus E' of which, measured at a frequency of 10 Hz and at 23° C., is less than the dynamic elastic modulus E' of the aforementioned first and second elastomeric materials.

[0031] On the other hand, as far as the "hot" use of the tire is concerned, the Applicant has found that the desired objectives of improving the handling and performance of the tire and keeping them constant for as long as possible can be achieved simultaneously by:

[0032] - maintaining the ratio between the “hot” dynamic elastic modulus (E′) of the second vulcanized elastomeric material used in the lateral sub-portions of the radially outer portion of the tread band and the “hot” dynamic elastic modulus (E′) of the third vulcanized elastomeric material used in the radially inner portion of the tread band at a value close to 1, i.e. maintaining the dynamic elastic moduli (E′) of these materials at values ​​very similar to each other; and

[0033] - keeping the ratio between the "hot" tan δ of the second and third vulcanized elastomeric materials and the ratio between the "hot" tan δ of the first and third vulcanized elastomeric materials at a value close to 1, ie keeping the tan δ of these materials at values ​​very similar to each other.

[0034] The Applicant has surprisingly discovered that by controlling within specific ratios, according to the zone of the tread band considered, the modulus and hysteresis values, and in particular the tan delta value, related to the conditions of use of the tire, of the vulcanized elastomeric material used to manufacture the various portions of the tread band, the "hot" handling and roadholding properties of the tire can both be improved and maintained over time at an optimal level, without compromising the handling and roadholding properties of the tire under the above-mentioned "cold" conditions of use.

[0035] In particular, an improvement in the handling and performance of the tire under "hot" use conditions is surprisingly achieved and maintained over time by using in the radially inner portion of the tread band a so-called "soft" vulcanized elastomeric material having, both under cold and hot conditions, a lower elastic modulus and a higher hysteresis than the two vulcanized elastomeric materials used in the radially outer portion of the tread band.

[0036] The improvement and maintenance over time of the handling and performance of the tire under "hot" use conditions is surprising, since the use of such a "soft" vulcanized elastomeric material in the radially inner part of the tread band would not only seem unsuitable for providing constant performance over time under such use conditions, but even, on the contrary, would tend to lead to a rapid degradation of tire performance.

[0037] The present invention therefore relates to a motorcycle tyre.

[0038] The motorcycle tyre comprises an equatorial plane and a tread band, the tread band comprising:

[0039] a) a radially outer portion, the radially outer portion comprising:

[0040] a1) a central sub-portion arranged astride the equatorial plane of the tyre and made of a first vulcanized elastomeric material, and

[0041] a2) a pair of lateral sub-portions distally located with respect to the equatorial plane of the tire and arranged on opposite sides of said central sub-portion, said lateral sub-portions being made of a second vulcanized elastomeric material;

[0042] wherein the dynamic elastic modulus (E') of the first vulcanized elastomeric material of the central sub-portion measured at a frequency of 10 Hz and 23° C. is greater than the dynamic elastic modulus (E') of the second vulcanized elastomeric material of the lateral sub-portion measured at a frequency of 10 Hz and 23° C.;

[0043] wherein the first vulcanized elastomeric material of the central sub-portion and the second vulcanized elastomeric material of the lateral sub-portion have a respective dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23° C. between 5.2 MPa and 6.5 MPa;

[0044] b) a radially inner portion extending underneath the radially outer portion of the tread band along the entire axial extent thereof, said radially inner portion being made of a third vulcanized elastomeric material having a dynamic modulus of elasticity (E') measured at a frequency of 10 Hz and at 23° C. that is smaller than the dynamic modulus of elasticity (E') measured at a frequency of 10 Hz and at 23° C. of said first vulcanized elastomeric material of a central sub-portion of the radially outer portion of the tread band and of said second vulcanized elastomeric material of lateral sub-portions of the radially outer portion of the tread band;

[0045] wherein the ratio R1 between the dynamic elastic modulus (E') of the second vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band, measured at a frequency of 10 Hz and 100° C., and the dynamic elastic modulus (E') of the third vulcanized elastomeric material of the radially inner portion of the tread band, measured at a frequency of 10 Hz and 70° C., is comprised between 0.8 and 1.2;

[0046] Therein, a ratio R2 between tan δ measured at 10 Hz and 100° C., of the second vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band and tan δ measured at 10 Hz and 70° C., of the third vulcanized elastomeric material of the radially inner portion of the tread band is comprised between 0.8 and 1.2.

[0047] The Applicant has experimentally discovered that, by using a tread band of the so-called "cap-base" type having the characteristics described above, it is surprisingly possible to improve and maintain over time the handling and performance of motorcycle tires, in particular motorcycle tires of the "supersport" and / or "ultrasport" type, under "hot" use conditions, while keeping the handling and roadholding properties in wet and / or cold climates or on less than optimal road surfaces essentially unchanged.

[0048] Without wishing to be bound by any explanatory theory, the Applicant believes that, under "hot" use conditions, a tyre as defined above has a substantially uniform tread band dynamic and hysteresis behaviour in the shoulder region, ie the region subjected to the greatest forces under such use conditions.

[0049] Applicants have discovered that such substantially uniform dynamic and hysteresis behavior is beneficial in limiting premature tire wear phenomena and tire performance degradation, and can be achieved by controlling the following ratio to a value close to 1:

[0050] i) the ratio between the deformation characteristics (related to the values ​​of the dynamic modulus of elasticity (E') in the corresponding "hot" use conditions) of the second vulcanized elastomeric material present in the lateral sub-portions or shoulder sub-portions of the radially outer portion of the tread band and the third vulcanized elastomeric material present in the radially inner portion of the tread band, and

[0051] ii) The ratio between the hysteresis characteristics (related to the tan delta values ​​under the above-mentioned corresponding "hot" use conditions) of the second vulcanized elastomeric material and the third vulcanized elastomeric material.

[0052] Surprisingly, this advantageous technical effect has been observed, as described above, by using a third vulcanized elastomeric material in the radially inner portion of the tread band, said third vulcanized elastomeric material having, under the conditions of use of the tire, a lower modulus of elasticity and a higher tan delta than the second vulcanized elastomeric material used in the shoulder regions of the radially outer portion of the tread band, characteristics which were supposed to lead to a rapid degradation of the tire's performance under "hot" conditions of use, but which have proven not to be the case. On the contrary, the third vulcanized elastomeric material actually allows to improve and maintain over time the handling and performance of the tire under "hot" conditions of use.

[0053] On the contrary, and again without wishing to be bound by any explanatory theory, the Applicant believes that, under "cold" conditions of use of the tire, the third vulcanized elastomeric material in the radially inner portion of the tread band undergoes deformations (related to the elastic modulus E') and hysteresis (related to the tan δ parameter), which allows "heating" of the overlying radially outer portion of the tread band (harder and less hysteretic), thereby making it better adhere to the ground in wet and / or cold conditions, thereby obtaining adequate handling and grip performances under these conditions of use.

[0054] Basically, in the tire according to the invention, the hysteresis characteristics in the shoulder areas of the tread band of the tire and the hysteresis characteristics under "hot" use conditions are effectively merged and the handling and grip performances under extreme speed and handling conditions on dry and / or hot surfaces are improved and maintained over time, while the stiffness and hysteresis characteristics under "cold" use conditions of the tire are effectively differentiated between different parts of the tread band, so as to maintain the handling and grip performances in wet and / or cold climate conditions or on less than optimal road surfaces.

[0055] In particular, under "hot" conditions of use, the assembly formed by lateral sub-portions or shoulder sub-portions of the radially outer portion of the tread band of a tyre according to the invention and by portions of the radially inner portion of the tread band situated below these sub-portions behaves, from the point of view of deformability and hysteresis, as if the assembly consisted essentially of a single vulcanized elastomeric material having the best properties under these conditions of use.

[0056] Advantageously, the tire according to the invention thus not only achieves improved handling and roadholding properties under extreme speed and handling conditions on dry and / or hot surfaces, but is also able to maintain such properties over a longer period of time.

[0057] Furthermore, under "hot" conditions of use, the assembly formed by the central sub-portion of the radially outer portion of the tread band and the portion of the radially inner portion of the tread band situated below this sub-portion of the tire of the invention also performs best, from the point of view of deformability and hysteresis, under conditions of running in a straight line, in which it is necessary to suppress any irregularities in the road surface as much as possible.

[0058] In this specification and the claims that follow, unless otherwise indicated, all numerical entities expressing amounts, parameters, percentages, etc., should be understood as being preceded in all instances by the term "about". In addition, except for those specifically indicated below, all numerical entity ranges include all possible combinations of maximum and minimum numerical values ​​and all possible intermediate ranges.

[0059] Unless otherwise specified, all numerical ranges also include the maximum and minimum values.

[0060] For purposes of the present invention, the following definitions apply.

[0061] The term "phr" (abbreviation for parts per hundred parts of rubber) denotes the parts by weight of a given component of an elastomeric rubber compound per 100 parts by weight of elastomeric polymer, the elastomeric polymer being considered to be free of any plasticizing, extending oil.

[0062] The terms "elastomeric material," "rubber," "elastomeric polymer," or "elastomer" are used to refer to a material comprising a vulcanizable natural or synthetic polymer and a reinforcing filler, wherein such material after vulcanization can withstand deformation caused by a force at room temperature and can quickly and strongly return to substantially the original shape and size after the deforming force is removed (as defined in ASTM Standard D1566-11 Standard Terminology Relating to Rubber).

[0063] The term "diene polymer" is used to denote a polymer or copolymer obtained by the polymerization of one or more different monomers, at least one of which is a conjugated diene (conjugated diene).

[0064] The terms “rubber compound” or “elastomeric rubber compound” are used to denote a mixture obtained by mixing and possibly heating at least one elastomeric polymer with at least one additive usually used in the preparation of rubber compounds for tires.

[0065] The terms "vulcanizable rubber compound" or "vulcanizable elastomeric rubber compound" are used to denote an elastomeric mixture ready for vulcanization, obtainable by incorporating into the elastomeric rubber compound all additives including vulcanizing additives.

[0066] The term "vulcanized elastomeric material" is used to denote a material obtained by vulcanizing a vulcanizable elastomeric rubber compound.

[0067] The term "vulcanization" is used to denote the crosslinking reaction in natural or synthetic rubber caused by a crosslinking agent, typically sulfur-based.

[0068] The term "vulcanizing agent" is used to denote a compound capable of converting 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, sulfur donors such as bis[(trialkoxysilyl)propyl]polysulfide, thiuram, dimorpholine dithioate and caprolactam disulfide.

[0069] The term "vulcanization accelerator" is used to denote compounds capable of reducing the duration of the vulcanization process and / or lowering the operating temperature, for example TBBS, sulfenamides, thiazoles, dithiophosphoric acids, dithiocarbamic acids, guanidines and sulfur donors such as thiuram.

[0070] The term "vulcanization activator" is used to denote a compound that is capable of further accelerating vulcanization, thereby allowing vulcanization to proceed in a shorter time and possibly at a lower temperature. An example of an activator is a stearic acid-zinc oxide system.

[0071] The term "vulcanization retardant" is used to denote a compound capable of delaying the onset of the vulcanization reaction and / or inhibiting undesirable side reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0072] The term "reinforcing filler" is used to denote reinforcing materials typically used to improve the mechanical properties of tire rubber, preferably chosen from carbon black and "white fillers".

[0073] The term "white filler" is used to denote conventional reinforcing materials used in this field, selected from conventional silicas and silicates, such as amorphous silica sand, preferably precipitated with strong acids, diatomaceous earth, calcium carbonate, titanium dioxide, talc, aluminum oxide, aluminosilicates, kaolin, silicate fibers, layered silicates (such as sepiolite, palygorskite (also known as attapulgite), montmorillonite, halloysite and the like, which are optionally modified and / or derivatized by acid treatment), and mixtures thereof. Typically, white fillers have surface hydroxyl groups.

[0074] The term "motorcycle tire" is used to denote a tire having a high curvature ratio (typically greater than 0.20) and capable of achieving high camber angles when cornering.

[0075] The term “curvature ratio” is used to indicate the ratio between the distance, in a section of the tire, between the radial highest point of the tread band and the maximum width of the radial section of the tire (also called “maximum chord”), this distance also represented by an “arrow”, and said maximum width.

[0076] The term "axial extension" of the tread band or portion thereof is used to denote the extension of the radially outermost contour of the tread band or portion thereof, in a section of the tyre taken in a plane containing the axis of rotation of the tyre.

[0077] The term "axial semi-extension" of a tread pattern, tread band or portion thereof is used to denote the extension of the radially outermost contour of the tread band or portion thereof, from the equatorial plane towards the axially outermost end of the tyre, in a section taken in a plane of the tyre containing the axis of rotation of the tyre.

[0078] The term "equatorial plane" of the tire means the plane perpendicular to the axis of rotation of the tire and dividing the tire into two symmetrically equal parts.

[0079] The term "width" is used to refer to the dimension measured in a direction perpendicular to the equatorial plane.

[0080] The term "tread pattern" is used to denote the presentation of all points of the tread band, including the grooves, on a plane perpendicular to the equatorial plane of the tyre and tangential to the greatest diameter of the tyre. The tread pattern is defined by a plurality of land portions separated by grooves and possibly including sipes.

[0081] The terms "radial" and "axial" and the expressions "radially inner / outer" and "axially inner / outer" are used by reference to a direction substantially parallel to the equatorial plane of the tire and a direction substantially perpendicular to the equatorial plane of the tire, respectively, i.e. by reference to a direction substantially perpendicular to the axis of rotation of the tire and a direction substantially parallel to the axis of rotation of the tire, respectively.

[0082] The terms "circumferential" and "circumferentially" are used with reference to the circumferential extension of the tire, ie with reference to its rolling direction, which direction corresponds to a plane lying in a plane coinciding with or substantially parallel to the equatorial plane of the tire.

[0083] The term "circumferential extension" of a tyre, a tread band or parts thereof is intended to denote the planar extension of the radially outermost surface of the tyre, the tread band or parts thereof, on a plane tangential to the tyre.

[0084] The expressions “axially innermost” and “axially outermost” respectively refer to positions closer to the equatorial plane and farther from the equatorial plane with respect to a reference element.

[0085] The term "radial carcass structure" is used to denote a carcass structure comprising a plurality of reinforcing cords, each oriented in a substantially axial direction in the crown portion of the tire. Such reinforcing cords may be incorporated into a single carcass ply or may be incorporated into a plurality of carcass plies (preferably two) radially superposed on each other.

[0086] The term "substantially axial direction" is intended to denote a direction inclined by an angle comprised between 60° and 90° with respect to the equatorial plane of the tyre.

[0087] The term "substantially circumferential direction" is used to denote a direction oriented at an angle comprised between 0° and 20° with respect to the equatorial plane of the tyre.

[0088] The term "static mechanical properties" of the tread rubber compound is used to denote the stress-strain properties of the vulcanized rubber and the thermoplastic rubber under traction measured at a predetermined temperature (170° C. for 10 minutes) on a sample of the vulcanized rubber compound according to UNI Standard 6065:2001.

[0089] The term "dynamic mechanical properties" of the tread rubber compound is used to refer to the mechanical properties measured in the traction-compression mode using an Instron dynamic apparatus model 1341 as described herein.

[0090] Cylindrical (length = 25 mm; diameter = 18 mm) test pieces of cross-linked material are used (170°C for 15 minutes), preloaded under compression to a longitudinal deformation of up to 25% of the initial length and maintained at a predetermined temperature (e.g., 23°C, 70°C and 100°C) throughout the test. After waiting for 2 minutes, the test pieces are mechanically preconditioned 125 times at 10 Hz with a deformation amplitude of 7.5% of the length under preload, and then the test pieces are subjected to a dynamic sinusoidal stress with an amplitude of ±3.5% of the length under preload and a predetermined frequency of, for example, 10 Hz. The dynamic mechanical properties are expressed as values ​​of the dynamic modulus of elasticity (E') and tan δ (loss factor). The tan δ value is calculated as the ratio between the dynamic modulus of viscosity (E") and the dynamic modulus of elasticity (E').

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

[0092] Preferably, the first vulcanized elastomeric material of the central sub-portion of the radially outer portion and the second vulcanized elastomeric material of the lateral sub-portions of the radially outer portion of the tread band have respective dynamic elastic moduli (E') measured at a frequency of 10 Hz and at 23°C comprised between 5.8 and 6.4 MPa.

[0093] In this way, it is advantageously possible to give the tread band sufficient stiffness properties in “cold” conditions of use of the tyre.

[0094] Preferably, the ratio R1 between the dynamic elastic modulus (E') of the second vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band, measured at a frequency of 10 Hz and 100°C, and the dynamic elastic modulus (E') of the third vulcanized elastomeric material of the radially inner portion of the tread band, measured at a frequency of 10 Hz and 70°C, is comprised between 0.9 and 1.1.

[0095] Advantageously, this preferred feature helps to optimize the handling and performance of the tire in extreme speed and handling conditions on dry and / or hot surfaces during cornering and to keep them substantially constant over time, since the shoulder areas of the tread band of the tire are formed from a vulcanized elastomeric material from the point of view of its "hot" deformation capabilities, while this vulcanized elastomeric material is substantially "homogeneous" from the point of view of its behavior on the road.

[0096] Preferably, the ratio R2 between tan δ measured at 10 Hz and 100°C of the second vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band and tan δ measured at 10 Hz and 70°C of the third vulcanized elastomeric material of the radially inner portion of the tread band is comprised between 0.9 and 1.1.

[0097] Also in this case, this preferred feature contributes to optimizing the handling and performance of the tire in extreme speed and handling conditions on dry and / or hot surfaces during cornering and keeping them substantially constant over time, since the shoulder areas of the tread band of the tire are formed from a vulcanized elastomeric material from the point of view of its "hot" deformation capabilities, while this vulcanized elastomeric material is substantially "homogeneous" from the point of view of its behavior on the road.

[0098] Preferably, the first vulcanized elastomeric 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 comprised between 5.1 and 5.5 MPa, more preferably between 5.2 and 5.4 MPa.

[0099] Preferably, the first vulcanized elastomeric material of the central sub-portion of the radially outer portion of the tread band has a tan delta measured at a frequency of 10 Hz and at 70° C. comprised between 0.26 and 0.30, more preferably between 0.27 and 0.29.

[0100] Preferably, the second vulcanized elastomeric 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 comprised between 2.5 and 2.9 MPa, more preferably between 2.6 and 2.8 MPa.

[0101] Advantageously, this preferred feature helps to achieve optimal ground contact properties and optimal grip of the tire on the ground, so as to improve the handling and performance of the tire in "hot" use conditions.

[0102] Preferably, the second vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band has a tan delta measured at a frequency of 10 Hz and at 100° C. comprised between 0.24 and 0.28, more preferably between 0.25 and 0.27.

[0103] Also in this case, this preferred feature advantageously contributes to achieving optimal ground contact properties and optimal grip of the tire on the ground, so as to improve the handling and performance of the tire in "hot" use conditions.

[0104] Preferably, the third vulcanized elastomeric 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 comprised between 2.5 and 2.9 MPa, more preferably between 2.6 and 2.8 MPa.

[0105] Advantageously, this preferred feature allows the third vulcanized elastomeric material of the radially inner portion of the tread band to contribute effectively to achieving optimal handling and performance of the tyre under "hot" use conditions.

[0106] In fact, under such "hot" conditions of use, the third vulcanized elastomeric material of the radially inner portion of the tread band has at the same time, under such "hot" conditions of use, deformable properties related to the value of the dynamic elastic modulus (E') which are appropriately differentiated in the various zones of the tread band and which enable high stability properties of the tread band as a whole to be achieved, from a dynamic point of view, under "hot" conditions of use.

[0107] In fact, the third vulcanized elastomeric material has deformation characteristics substantially identical to those of the second vulcanized elastomeric material of the shoulder sub-portions of the radially outer portion of the tread band, but much lower than those of the first vulcanized elastomeric material of the central sub-portion of the radially outer portion of the tread band, thus allowing to "mimic" the hysteresis behaviour of the shoulder portions and to "heat up" the central sub-portion of the tread band formed by a less deforming rubber compound.

[0108] Preferably, the third vulcanized elastomeric material of the radially inner portion of the tread band has a tan delta measured at a frequency of 10 Hz and at 70° C. comprised between 0.25 and 0.29, more preferably between 0.26 and 0.28.

[0109] Advantageously, this preferred feature also allows the third vulcanized elastomeric material of the radially inner portion of the tread band to effectively contribute to achieving optimal handling and performance of the tire under "hot" use conditions, in which case said third vulcanized elastomeric material has a hysteresis characteristic related to the tan δ value that is substantially the same as the hysteresis characteristics of the first and second vulcanized elastomeric materials of the radially outer portion of the tread band.

[0110] Preferably, the first vulcanized elastomeric 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 23°C comprised between 6.0 and 6.5 MPa, more preferably between 6.2 and 6.4 MPa.

[0111] Preferably, the first vulcanized elastomeric material of the central sub-portion of the radially outer portion of the tread band has a tan delta measured at a frequency of 10 Hz and at 23° C. comprised between 0.40 and 0.44, more preferably between 0.41 and 0.43.

[0112] Preferably, the second vulcanized elastomeric 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 23°C comprised between 5.5 and 6.0 MPa, more preferably between 5.7 and 5.9 MPa.

[0113] Preferably, the second vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band has a tan delta measured at a frequency of 10 Hz and at 23° C. comprised between 0.66 and 0.70, more preferably between 0.67 and 0.69.

[0114] In this way, it is advantageously possible to achieve optimal grip of the tyre on the ground in order to improve the handling and performance of the tyre in “cold” conditions of use.

[0115] Preferably, the third vulcanized elastomeric material of the radially inner portion of the tread band has a dynamic elastic modulus (E'), measured at a frequency of 10 Hz and at 23°C, comprised between 4.0 and 5.0 MPa, more preferably between 4.2 and 4.5 MPa.

[0116] Advantageously, this preferred feature allows the third vulcanized elastomeric material of the radially inner portion of the tread band to effectively contribute to achieving an optimal ground contact area and an optimal grip of the tyre on the ground, so as to improve the handling and performance of the tyre in "cold" conditions of use.

[0117] Preferably, the third vulcanized elastomeric material of the radially inner portion of the tread band has a tan delta measured at a frequency of 10 Hz and at 23° C. comprised between 0.49 and 0.53, more preferably between 0.50 and 0.52.

[0118] Advantageously, this preferred feature also allows the third vulcanized elastomeric material of the radially inner portion of the tread band to effectively contribute to achieving an optimum ground contact area and an optimum grip of the tyre on the ground, so as to improve the handling and performance of the tyre in "cold" conditions of use.

[0119] Preferably, the ratio R3 between the tan δ measured at a frequency of 10 Hz and 70°C of the first vulcanized elastomeric material of 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 elastomeric material of the radially inner portion of the tread band is comprised between 0.5 and 1.2, more preferably between 0.7 and 1.0.

[0120] In this way, the handling and performance of the tire under "hot" conditions of use and during travel in a straight line can be advantageously optimized and kept substantially constant over time, since the central zone of the tread band of the tire is formed, both in its radially outer part and in its radially inner part, from a vulcanized elastomeric material that is substantially "homogeneous" from a hysteresis point of view.

[0121] Preferably, the ratio R4 between the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70°C of the first vulcanized elastomeric material of 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 elastomeric material of the radially inner portion of the tread band is between 1.3 and 2.0, more preferably between 1.5 and 1.8.

[0122] In this way, the handling and the performance of the tyre under fast running conditions on dry and / or hot surfaces during travel in a straight line can be advantageously optimized and kept substantially constant over time, since the central zone of the tread band of the tyre is formed by a vulcanized elastomeric material which, from the point of view of its "hot" deformation capabilities, adapts well to the roughness of the ground owing to the modulus characteristics of the central sub-portion of the radially outer portion of the tread band and, at the same time, achieves high grip owing to the modulus characteristics of the radially inner portion of the tread band.

[0123] Preferably, the ratio R5 between the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C of the second vulcanized elastomeric material of the lateral 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 23°C of the third vulcanized elastomeric material of the radially inner portion of the tread band is between 1.1 and 1.6, more preferably between 1.2 and 1.5.

[0124] In this way, it is advantageously possible to achieve excellent handling and performance levels of the tire in "cold" conditions of use, for example during the warming-up phase of the tire or in demanding camber conditions on bends on wet ground and / or in cold climate conditions or on non-optimal road surfaces.

[0125] Without being bound by any explanatory theory, the Applicant considers that, in this case, the third vulcanized elastomeric material of the radially inner portion of the tread band allows the lateral or shoulder sub-portions of the radially outer portion of the tread band to deform sufficiently, thereby increasing their ground contact area.

[0126] Preferably, the ratio R6 between the tan δ measured at a frequency of 10 Hz and 23°C of the second vulcanized elastomeric material of the lateral sub-portion of the radially outer portion of the tread band and the tan δ measured at a frequency of 10 Hz and 23°C of the third vulcanized elastomeric material of the radially inner portion of the tread band is comprised between 1.1 and 1.6, more preferably between 1.2 and 1.5.

[0127] Preferably, the ratio R7 between the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C of the first vulcanized elastomeric material of 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 23°C of the third vulcanized elastomeric material of the radially inner portion of the tread band is between 1.2 and 1.8, more preferably between 1.3 and 1.7.

[0128] Preferably, the ratio R8 between the tan δ measured at a frequency of 10 Hz and 23°C of the first vulcanized elastomeric material of 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 23°C of the third vulcanized elastomeric material of the radially inner portion of the tread band is comprised between 0.6 and 1.1, preferably between 0.7 and 1.0.

[0129] In this way, it is advantageously possible to achieve excellent handling and performance levels of the tire in "cold" use conditions, for example during the warm-up phase of the tire or when running in a straight line on wet ground and / or in cold weather conditions or on non-optimal road surfaces.

[0130] Without being bound by any explanatory theory, the Applicant considers that, in this case, the hysteresis of the third vulcanized elastomeric material of the radially inner portion of the tread band is substantially equal to or appropriately greater than the hysteresis of the first vulcanized elastomeric material of the central sub-portion of the radially outer portion of the tread band, thereby allowing sufficient thermal operation of the aforementioned central sub-portion, increasing its ground contact area.

[0131] Preferably, the ratio R9 between the dynamic elastic modulus (E') of the third vulcanized elastomeric material of the radially inner portion of the tread band measured at a frequency of 10 Hz and 23°C and the dynamic elastic modulus (E') of the same vulcanized elastomeric material measured at a frequency of 10 Hz and 70°C is between 1.2 and 2.0, more preferably between 1.4 and 1.9.

[0132] Advantageously, this preferred feature allows the third vulcanized elastomeric material of the radially inner portion of the tread band to have an optimal "flexibility" of its deformation characteristics both under "cold" and "hot" conditions of use, which flexibility effectively contributes to achieving the following advantageous technical effects.

[0133] Firstly, a technical effect which contributes to improving and maintaining over time the handling and performance of the tyre under "hot" conditions of use, due to the collaboration between the third vulcanized elastomeric material of the radially inner portion of the tread band and the second vulcanized elastomeric material of the lateral sub-portions or shoulder sub-portions of the radially outer portion of the tread band, the "hot" dynamic elastic moduli, i.e. the degrees of deformation, of these elastomeric materials being very close to one another (see the value of the aforementioned ratio R1).

[0134] Secondly, a technical effect which contributes to maintaining an excellent handling and performance level of the tyre in "cold" conditions of use (for example during the warming-up phase of the tyre or when used on wet ground and / or in cold climatic conditions or on less than optimal road surfaces), thanks to the collaboration 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, the "cold" dynamic elastic modulus, i.e. the degree of deformation, of these elastomeric materials being significantly differentiated from one another (see the value of the aforementioned ratio R7).

[0135] In fact, under "cold" conditions of use of the tyre, the third vulcanized elastomeric material of the radially inner portion of the tread band has a much higher deformability and hysteresis than the first vulcanized elastomeric material of the central sub-portion of the radially outer portion of the tread band, thereby facilitating the heating of the tread band during the warm-up phase and contributing to increasing the grip of the tyre on wet surfaces and / or in cold climates or on non-optimal road surfaces at "cold" operating temperatures.

[0136] Preferably, the ratio R10 between tan δ measured at 10 Hz and 23°C of the third vulcanized elastomeric material of the radially inner portion of the tread band and tan δ measured at 10 Hz and 70°C of the same vulcanized elastomeric material is comprised between 1.5 and 2.4, more preferably between 1.7 and 2.1.

[0137] Advantageously, this preferred feature also allows the third vulcanized elastomeric material of the radially inner portion of the tread band to have optimal "flexibility" of its hysteresis properties both in "cold" and "hot" conditions of use, which flexibility effectively contributes to achieving the advantageous technical results mentioned above.

[0138] Preferably, the tyre is a tyre for a motorcycle rear wheel, having a transverse curvature ratio equal to or greater than about 0.30 and preferably comprised between 0.30 and 0.35. BRIEF DESCRIPTION OF THE DRAWINGS

[0139] Other characteristics and advantages of the invention will become more apparent from the following description of some preferred embodiments given for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0140] The Figures are schematic and not drawn to scale.

[0141] In the attached picture:

[0142] - Figure 1 a perspective view showing a tyre according to a preferred embodiment of the invention, intended to be mounted on the rear wheel of a motorcycle; and

[0143] - Figure 2 yes Figure 1 An enlarged schematic diagram of a cross section of a tire. DETAILED DESCRIPTION

[0144] In the drawings, reference numeral 1 denotes as a whole a tyre for motorcycle wheels according to a preferred embodiment of the invention. This is a tyre preferably intended for the rear wheel of a super sports motorcycle of large displacement (eg 600cc).

[0145] An equatorial plane XX and an axis of rotation (not shown) are defined in the tire 1. A circumferential direction (in Figure 1 1) and the axial direction (indicated by an arrow F oriented in the direction of rotation of the tire 1). Figure 2 denoted by the axis r perpendicular to the equatorial plane XX).

[0146] The tyre 1 comprises a carcass structure 2 formed by at least one carcass layer 3 comprising a plurality of reinforcing elements (cords).

[0147] The carcass structure 2 is typically coated on its inner wall with a sealing layer or so-called "liner" consisting mainly of a layer of airtight elastomeric material suitable for ensuring an airtight seal when the tyre is inflated.

[0148] The reinforcing elements contained in the carcass layer 3 preferably comprise textile cords made of fiber material.

[0149] The fiber material used to make the cords may be made of fibers of natural or synthetic origin, chosen from rayon, lyocell, polyesters (e.g. PEN, PET, PVA), aromatic polyamides (e.g. Aramid), these can be alone or mixed. More particularly, the fiber material for making the cord is preferably selected from polyester, rayon, lyocell, aromatic polyamides, or a mixed material formed by two or more of the above materials.

[0150] The reinforcing elements comprised in at least one carcass layer 3 are preferably arranged in radial direction, ie at an angle of between 70° and 110°, more preferably between 80° and 100°, relative to the circumferential direction.

[0151] The at least one carcass layer 3 is shaped according to a substantially annular configuration and is joined by its opposite circumferential edges 3a to at least one annular reinforcing structure.

[0152] In particular, the relative lateral edges 3a of at least one carcass layer 3 can be turned up around the annular reinforcement structure, each annular reinforcement structure includes one or more metal annular bead cores 4 and conical elastomeric fillers 5, and the conical elastomeric fillers occupy the space defined between the carcass layer 3 and the corresponding turned-up lateral edges 3a of the carcass layer 3.

[0153] The region of the tyre comprising the bead core 4 and the filler 5 forms the so-called bead 9 intended to anchor the tyre 1 on a corresponding mounting rim (not shown).

[0154] In an embodiment not shown, at least one carcass layer 3 is made by bringing together a plurality of strips of elastomeric material reinforced by the aforementioned cords and its opposite lateral edges are associated without turning up with a specific annular reinforcing structure provided with two annular inserts. A filler made of elastomeric material can be arranged in an axially external position relative to the first annular insert. On the other hand, a second annular insert can be arranged in an axially external position relative to the end of the carcass layer. Finally, in an axially external position relative to the second annular insert (and not necessarily in contact with it), another filler can be arranged, which completes the construction of the annular reinforcing structure.

[0155] Circumferentially applied to the carcass structure 2 at a radially external position is a belt structure 6 comprising at least one belt layer 6a, typically formed of rubber-coated cords.

[0156] Preferably, the belt layer 6a is made of cords substantially parallel to each other and arranged side by side to form a plurality of coils. Such coils are oriented substantially according to a circumferential direction (typically with an angle between 0° and 5°), this direction generally referred to as "zero degrees" with reference to the direction in which they are laid relative to the circumferential direction of the tire.

[0157] Preferably, the "zero degree" layer 6a may comprise axially adjacent windings of a single cord, or a rubberized fabric tape comprising axially adjacent cords.

[0158] The cords of layer 6a are textile cords or metal cords. Preferably, the cords are metal cords made of steel wires with a high carbon content, in other words, with a carbon content of at least 0.6%-0.7%.

[0159] Preferably, such metal cords have a high elongation (HE).

[0160] In order to improve the adhesion between the belt structure 6 and the carcass structure 2, an adhesion layer 7 made of elastomeric material may be arranged between these two structures.

[0161] In an embodiment not shown, the belt structure 6 may consist of at least two radially superposed layers arranged so that the cords of the first belt layer are oriented obliquely with respect to the circumferential direction of the tire, while the cords of the second layer also have an oblique orientation but cross substantially symmetrically with respect to the cords of the first layer.

[0162] Circumferentially superimposed on the belt structure 6 is a tread band 8 on which, after a moulding operation simultaneous with the vulcanisation of the tyre, longitudinal and / or transverse grooves are typically formed, these grooves being arranged so as to define the desired tread pattern.

[0163] Figure 1 As a non-limiting example, a tread pattern is shown comprising a plurality of grooves arranged in different ways on opposite sides of the equatorial plane XX of the tyre 1 .

[0164] Preferably, the tread pattern includes a series of first circumferential grooves 13 that are basically L-shaped, a series of second circumferential grooves 14 that are located at an axially outer position relative to the first circumferential grooves 13, and a series of third circumferential groove groups 15a, 15b, 15c and 15d, which have different inclinations relative to the equatorial plane XX of the tire 1 and are circumferentially inserted between the first circumferential grooves 13.

[0165] To keep it simple, Figure 2 These grooves are not shown in FIG.

[0166] The tyre 1 may comprise a pair of sidewalls 10 applied laterally to said carcass structure 2 on opposite sides thereof.

[0167] The tyre 1 has a cross-sectional height H measured on the equatorial plane XX between the top of the tread band 8 and the fitting diameter passing through the beads of the tyre 1 , identified by the reference line r.

[0168] The tyre 1 also has a maximum width C of its transverse section, defined by the distance between the axially opposite ends E of the profile of the tread band 8, and a curvature ratio defined as the ratio between the distance f of the top of the tread band 8 from a line passing through the ends E of the tread band 8 itself (measured on the equatorial plane of the tyre 1) and the aforementioned maximum width C. The axially opposite ends E of the tread band 8 may be formed at edges.

[0169] In particular, tyre 1 has a transverse section characterized by a high curvature ratio, preferably said curvature ratio f / C being at least about 0.30.

[0170] In a preferred embodiment, the motorcycle tyre 1 of the present invention is intended to be mounted on a rear wheel having a chord length dimension generally between 160 mm and 210 mm.

[0171] Preferably, the distance f between the radially outermost point of the tread band 8 and a line passing through the axially opposite ends E of the tread band 8 itself of the tyre 1 is substantially comprised between 50 and 70 mm.

[0172] Preferably, for a tyre 1 intended to be mounted on the rear wheel of a motorcycle, the transverse curvature ratio f / C is substantially equal to or greater than about 0.30, even more preferably comprised between 0.30 and 0.35.

[0173] Preferably, the overall height / chord length ratio H / C is approximately between 0.5 and 0.65.

[0174] In a preferred embodiment, the tire allows achieving better performance when the tire 1 has a sidewall 10 of significant height, for example when the tire 1 is intended to be mounted on the rear wheel of a motorcycle, the value of the sidewall height ratio (Hf) / H is equal to or greater than 0.35, more preferably equal to or greater than 0.4.

[0175] Preferably, the ratio between the shoulder radius and the maximum section width of the tire 1 is equal to or greater than 0.60.

[0176] According to the invention, the tread band 8 is of the so-called “cap and base” type and is made of at least three different elastomeric materials.

[0177] In the preferred embodiment shown in the accompanying drawings, the tread band 8 comprises a radially outer portion 11 comprising:

[0178] a1) a central sub-portion 11a arranged astride the equatorial plane XX of the tyre 1 and made of a first vulcanized elastomeric material, and

[0179] a2) A pair of lateral sub-portions 11 b, 11 c located distally with respect to the equatorial plane XX of the tyre 1 and arranged on opposite sides of the central sub-portion 11 a.

[0180] As mentioned above, the lateral sub-portions 11b, 11c of the tread band 8 are made of a second vulcanized elastomeric material.

[0181] In the preferred embodiment shown in the accompanying drawings, the tread band 8 comprises a radially inner portion 12 extending underneath the radially outer portion 11 of the tread band 8 along the entire axial extension thereof.

[0182] As mentioned above, the radially inner portion 12 of the tread band 8 is made of a third vulcanized elastomeric material.

[0183] Preferably, the annular central sub-portion 11a of the tread band 8 has an axial extension L1 extending transversely 25% - 40% of the total axial extension L of the tread band 8, more preferably 30% - 35% thereof.

[0184] Preferably, the lateral sub-portions 11b, 11c of the tread band 8 have a respective axial extension L2, L3 extending transversely 25% - 40% of the total axial extension L of the tread band 8, more preferably 30% - 35% thereof.

[0185] The central sub-portion 11a of the radially outer portion 11 of the tread band 8 is advantageously formed in one piece, for example as a continuous circumferential spiral laying down at least one continuous elongated element of the aforementioned first vulcanized elastomeric material.

[0186] Conversely, the lateral sub-portions 11b, 11c of the tread band 8 are advantageously formed in one piece, for example laying down a continuous circumferential coil of at least one continuous elongated element made of the aforementioned second vulcanized elastomeric material.

[0187] In this way and as described above, a pair of interfaces 16 between the first and second vulcanized elastomeric materials are defined in the radially outer portion 11 of the tread band 8 and on opposite sides of the equatorial plane XX of the tyre 1 and of the central annular portion 11a.

[0188] Thus, in this preferred configuration of the tread band 8, the interface 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 in the axial direction.

[0189] Preferably, the lateral sub-portions 11b, 11c of the radially outer portion 11 of the tread band 8 and therefore the interface 16 are arranged at a distance from the equatorial plane XX of the tyre 1, as stated above, which is comprised between 25% and 40% of the semi-axial extension L / 2 of the tread band, more preferably between 30% and 35% thereof.

[0190] exist Figure 2 In the preferred embodiment shown, the interface 16 may converge from the inside to the outside of the tread band 8 towards the equatorial plane XX of the tyre 1, said interface being oriented according to an angle inclined relative to the equatorial plane XX between 30° and 50°, preferably between 35° and 40°.

[0191] 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 extension of the belt structure 6 .

[0192] Therefore, in this preferred configuration of the tread band 8, the radially inner portion 12 of the tread band 8 is interposed in radial direction between the belt structure 6, the central subportion 11a and the lateral subportions 11b, 11c of the radially outer portion 11 of the tread band 8.

[0193] The rubber compounds used for the different parts of the tread band 8 and for forming other semi-finished products of the tyre 1 comprise at least one elastomeric diene polymer (a1).

[0194] Advantageously, this rubber compound includes at least one alpha-olefin and has a specific formulation, as will be described in more detail below.

[0195] According to one embodiment, the at least one elastomeric diene polymer (a1) may be chosen, for example, from elastomeric diene polymers commonly used in elastomeric compositions capable of crosslinking (vulcanization) with sulfur, particularly suitable for the manufacture of tires, i.e. from elastomeric polymers or copolymers with unsaturated chains, the glass transition temperature (Tg) of which is generally below 20° C., preferably in the range of 0° C. to 110° C. These polymers and copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas phase polymerization of one or more conjugated dienes, optionally mixed with at least one comonomer chosen from monovinylarenes and / or polar comonomers.

[0196] 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.

[0197] Preferably, styrene-butadiene polymer (SBR) may be present in the rubber compound of the present invention in various amounts ranging from about 50 phr to 100 phr, more preferably in the range of 70 phr to 100 phr.

[0198] Advantageously, polybutadiene (BR) may be absent from the rubber compound of the invention or may be included in the rubber compound of the invention, in particular in the tread rubber compound, in an amount of about 0 to 40 phr, more preferably about 10 to 30 phr.

[0199] Preferably, the styrene-butadiene polymer is obtainable from a solution or an emulsion and generally comprises styrene in an amount of about 10 to 40%, preferably about 15 to 30% by weight.

[0200] Preferably, the styrene-butadiene polymer may be of low molecular weight, with an average molecular weight Mn below 200,000 g / mol, preferably between 150,000 and 200,000 g / mol.

[0201] The elastomeric material of the different portions of the tread band 8 comprises at least one reinforcing filler present in an amount generally comprised between 1 and 130 phr.

[0202] Such reinforcing fillers are preferably chosen from carbon black and the so-called white fillers: silica, alumina, silicates, hydrotalcite, calcium carbonate, kaolin, titanium dioxide and mixtures thereof.

[0203] The reinforcing filler used in the elastomeric material of the different portions of the tread band 8 may comprise carbon black alone, or may comprise both carbon black and one or more white fillers, such as silica.

[0204] In a preferred embodiment, the first vulcanized elastomeric material of the central sub-portion 11a of the radially outer portion 11 of the tread band 8 comprises a "white" reinforcing filler as defined above, in an amount greater than 75% by weight of the total weight of the reinforcing filler, preferably equal to or greater than 80%, more preferably equal to or greater than 85%, more preferably equal to or greater than 90%, more preferably equal to or greater than 95%.

[0205] More preferably, such "white" reinforcing fillers are selected from silica, alumina, silicates, hydrotalcite, calcium carbonate, kaolin, titanium dioxide and mixtures thereof.

[0206] Even more preferably, the "white" reinforcing filler may be fumed silica or precipitated silica, the BET surface area of ​​which (measured according to ISO standard 5794 / 1) is between 50 m 2 / g and 500m 2 / g, preferably between 70m 2 / g and 200m 2 / g.

[0207] In this way, rapid warming up of the tread band 11 of the tyre 1 and excellent gripping properties under different road conditions can advantageously be achieved.

[0208] 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 comprises carbon black in an amount by weight greater than 75%, preferably equal to or greater than 80%, more preferably equal to or greater than 85%, more preferably equal to or greater than 90%, more preferably equal to or greater than 95%, relative to the total weight of the reinforcing filler.

[0209] Preferably, the carbon black is selected from carbon black having a surface area of ​​not less than 20 m 2 / g, preferably greater than 50m 2 / g of carbon black (determined by STSA-Statistical Thickness Surface Area according to ISO18852:2005).

[0210] The carbon black may for example be N234, N326, N330, N375, N550 or N660 sold by Birla Group (India) or CRX 1391 sold by Cabot Corporation.

[0211] Reinforcing fillers may include mixtures, for example, a mixture of carbon black and silica.

[0212] In this way, optimal support during cornering and optimal traction during acceleration can advantageously be achieved in order to manage the torque generated by a high-performance motorcycle, such as a last generation superbike.

[0213] The above-mentioned elastomeric composition, as well as the elastomeric compositions of the other components of the tire 1, can be vulcanized according to known techniques, in particular using sulfur-based vulcanization systems commonly used for elastomeric polymers. To this end, in the elastomeric composition, after one or more thermomechanical treatment steps, a sulfur-based vulcanizing agent is incorporated together with a vulcanization accelerator. In the final step of the treatment, the temperature is generally kept below 140°C in order to avoid any undesirable pre-crosslinking phenomena.

[0214] The vulcanizing agents most advantageously used are sulfur or sulfur-containing molecules (sulfur donors) with accelerators and activators known to those skilled in the art.

[0215] Particularly effective activators are: zinc-based compounds, especially ZnO, ZnCO 3 , a zinc salt of a saturated or unsaturated fatty acid containing 8 to 18 carbon atoms (e.g., zinc stearate), preferably formed in situ from ZnO and a fatty acid in the elastomer composition; and BiO, PbO, Pb 3 O 4 , PbO 2 or a mixture thereof.

[0216] Commonly used accelerators may be selected from: dithiocarbamates, guanidines, thioureas, thiazoles, sulfonamides, thiourams, amines, xanthates or mixtures thereof.

[0217] The elastomeric compositions used may include other additives which are generally selected according to the specific use of each composition.

[0218] For example, the following additives may be added to the elastomeric composition: antioxidants, anti-aging agents, plasticizers, adhesives, antiozonants, modifying resins, fibers (aramid or fibers of natural origin) or mixtures thereof.

[0219] In the following Table 1, examples are given for indication purposes only of rubber compounds which, after vulcanization, make up the first, second and third vulcanized elastomeric materials of a preferred embodiment of the tyre 1 .

[0220] The amounts of the various components in the elastomeric composition are generally provided in phr as defined above.

[0221] Table 1

[0222]

[0223]

[0224] *phr of dry polymer without extender oil

[0225] S-SBR: solution polymerized styrene-butadiene copolymer (phr is given as dry polymer, 37.5 phr of TDAE oil is added per 100 phr of dry elastomeric polymer) - TUFDENE E680 (Asahi Kasei)

[0226] E-SBR: emulsion polymerized styrene-butadiene copolymer (phr given as dry polymer, 37.5 phr of RAE oil added per 100 phr of dry elastomeric polymer) - INTOL 1789 (Versalis)

[0227] BR: Functionalized low cis polybutadiene-YB03 (Asahi Kasei)

[0228] CB:CRX TM 1391(Cabot)

[0229] Silica: 7000 (Evonik)

[0230] Liquid copolymer (grip enhancer): low molecular weight butadiene / styrene liquid copolymer (4500g / mol) - 100(Cray Valley)

[0231] Extender oil: TDAE (Orgkhim)

[0232] Lubricant: Tri(2-ethylhexyl) phosphate (TOF) (Lanxess)

[0233] Resin 1: Hydrocarbon resin - 5140LV(Eastman)

[0234] Resin 2: Hydrocarbon resin - TT 90 (Lanxess)

[0235] Resin 3: Hydrocarbon resin - TT 30 (Reutgers Germany GmbH)

[0236] Zinc salt: Zinc neodecanoate 50 (Rhein Chemie)

[0237] Stearic acid: Stearic acid (Undesa)

[0238] Zinc Oxide: ZnO(Zincol Ossidi)

[0239] Silane: SILAN (Evonik)

[0240] Zinc stearate: ACID GRAS SARE DE ZINC (Eigenmann & Veronelli)

[0241] Wax: WAX (Repsol)

[0242] Antioxidant: 2,2,4-trimethyl-1,1-dihydroquinoline -TMQ (Lanxess)

[0243] Antiozonant: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine 6PPD (Eastman)

[0244] sulfur: IS 90P (Rhein Chemie)

[0245] Crosslinker: difunctional 1,6-bis(NN'-dibenzylthiocarbamoyldisulfide)-hexane- KA 9188 (Lanxess)

[0246] Adhesion promoter: hexamethylene-1,6-bis(thiosulfate) disodium dihydrate salt - HTS(Eastman)

[0247] Vulcanization accelerator 1: N-tert-butylbenzothiazolesulfenamide-TBBS (Huatai Chemicals)

[0248] Vulcanization accelerator 2: dibenzothiazyl disulfide- MBTS 80 (Rhein Chemie)

[0249] Vulcanization accelerator 3: Tetrabenzylthiuram disulfide - TBZTD (Akrochem)

[0250] Vulcanization retarder: N-(cyclohexylthio)phthalimide-PVI (Akrochem)

[0251] According to the invention, the first vulcanized elastomeric material of the central subportion 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 23°C greater than the dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C of the second vulcanized elastomeric material of the lateral subportions 11b, 11c.

[0252] Furthermore, the first vulcanized elastomeric material of the central subportion 11a and the second vulcanized elastomeric material of the lateral subportions 11b, 11c of the radially outer portion 11 of the tread band 8 have respective dynamic elastic moduli E' measured at a frequency of 10 Hz and at 23°C comprised between 5.2 and 6.5 MPa, preferably between 5.8 and 6.4 MPa.

[0253] Still according to the present invention, the dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C by the third vulcanized elastomeric material of the radially inner portion 12 of the tread band 8 is smaller than the dynamic elastic modulus E' measured at a frequency of 10 Hz and 23°C by the aforementioned first vulcanized elastomeric material of the central sub-portion 11a and the aforementioned second vulcanized elastomeric material of the lateral sub-portions 11b, 11c of the radially outer portion 11 of the tread band 8.

[0254] As stated above, the Applicant believes that, under "cold" use conditions of the tire 1, the third vulcanized elastomeric material in the radially inner portion 12 of the tread band 8 undergoes (at the lateral or shoulder portions of the tire) deformations (related to the elastic modulus E') and hysteresis (related to the tan δ parameter) that allow "heating" of the overlying radially outer portion 11 of the tread band 8 (harder and less hysteretic), thereby making it better adhere to the ground in wet and / or cold conditions.

[0255] According to the present invention, the ratio R1 between the dynamic elastic modulus E' of the second vulcanized elastomeric material of the lateral sub-portions 11b, 11c of the radially outer portion 11 of the tread band 8, measured at a frequency of 10 Hz and 100°C, and the dynamic elastic modulus E' of the third vulcanized elastomeric material of the radially inner portion 12 of the tread band 8, measured at a frequency of 10 Hz and 70°C, is between 0.8 and 1.2, preferably between 0.9 and 1.1.

[0256] Furthermore, a ratio R2 between the tan δ of the second vulcanized elastomeric material of the lateral sub-portions 11b, 11c of the radially outer portion 11 of the tread band 8, measured at a frequency of 10 Hz and 100°C, and the tan δ of the third vulcanized elastomeric material of the radially inner portion 12 of the tread band 8, measured at a frequency of 10 Hz and 70°C, is between 0.8 and 1.2, preferably between 0.9 and 1.1.

[0257] As mentioned above, the Applicant has experimentally observed that by controlling the above-mentioned ratio R1 between the deformation characteristics related to the value of the dynamic elastic modulus E' and the ratio R2 between the hysteresis characteristics related to the value of tan δ to a value close to 1, it is possible, under "hot" use conditions of the tire, to have both optimal dynamic and hysteresis behavior in the shoulder area, thereby limiting premature wear and performance degradation, and optimal dynamic and hysteresis behavior in the central area, thereby ensuring optimal running performance along a straight line.

[0258] The tire 1 may also be provided with one or more of the above-mentioned preferred features, thereby achieving corresponding advantageous technical effects.

[0259] The invention will now be described by means of some examples which are considered for illustrative purposes only and not for limiting purposes.

[0260] Properties of the vulcanized elastomeric compositions

[0261] In the following Table 2, examples are given for illustration purposes only of rubber compounds which, after vulcanization, give the first, second and third vulcanized elastomeric materials of a particularly preferred embodiment of the tyre 1 .

[0262] The amounts of the various components in the elastomeric composition are generally provided in phr as defined above.

[0263] Table 2

[0264]

[0265]

[0266] *phr of dry polymer without extender oil

[0267] S-SBR: solution polymerized styrene-butadiene copolymer (phr is given as dry polymer, 37.5 phr of TDAE oil is added per 100 phr of dry elastomeric polymer) - TUFDENE E680 (Asahi Kasei)

[0268] E-SBR: emulsion polymerized styrene-butadiene copolymer (phr given as dry polymer, 37.5 phr of RAE oil added per 100 phr of dry elastomeric polymer) - INTOL 1789 (Versalis)

[0269] BR: Functionalized low cis polybutadiene-YB03 (Asahi Kasei)

[0270] CB:CRX TM 1391(Cabot)

[0271] Silica: 7000 (Evonik)

[0272] Liquid copolymer: low molecular weight butadiene / styrene liquid copolymer (4500g / mol) - 100(Cray Valley)

[0273] Extender oil: TDAE (Orgkhim)

[0274] Lubricant: Tri(2-ethylhexyl) phosphate (TOF) (Lanxess)

[0275] Resin 1: Hydrocarbon resin - 5140LV(Eastman)

[0276] Resin 2: tert-butylphenol resin (BASF)

[0277] Resin 3: Hydrocarbon resin - TT 90 (Lanxess)

[0278] Zinc salt: Zinc neodecanoate 50 (Rhein Chemie)

[0279] Stearic acid: Stearic acid (Undesa)

[0280] Zinc Oxide: ZnO(Zincol Ossidi)

[0281] Silane: SILAN (Evonik)

[0282] Zinc stearate: ACID GRAS SARE DE ZINC (Eigenmann & Veronelli)

[0283] Wax: WAX (Repsol)

[0284] Antioxidant: 2,2,4-trimethyl-1,1-dihydroquinoline -TMQ (Lanxess)

[0285] Antiozonant: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine 6PPD (Eastman)

[0286] sulfur: IS 90P (Rhein Chemie)

[0287] Crosslinker: difunctional 1,6-bis(NN'-dibenzylthiocarbamoyldisulfide)-hexane- KA 9188 (Lanxess)

[0288] Adhesion promoter: hexamethylene-1,6-bis(thiosulfate) disodium dihydrate salt - HTS(Eastman)

[0289] Vulcanization accelerator 1: N-tert-butylbenzothiazolesulfenamide-TBBS (Huatai Chemicals)

[0290] Vulcanization accelerator 2: dibenzothiazyl disulfide- MBTS 80 (Rhein Chemie)

[0291] Vulcanization accelerator 3: N-tert-butylbenzothiazolesulfenamide-TBBS 80 (Rhein Chemie)

[0292] Vulcanization retarder: N-(cyclohexylthio)phthalimide-PVI (Akrochem)

[0293] Table 3 below shows the results of static and dynamic mechanical analyses carried out on samples of three material compositions, the formulations of which are indicated in Table 1 above, for the radially inner portion 12 and the radially outer portion 11 of the tread band 8 of a tyre 1 according to the invention.

[0294] These analyses were performed under temperature and frequency conditions and according to the techniques described above.

[0295] Table 3

[0296]

[0297]

[0298] Table 4 below shows the ratios between various vulcanized elastomeric materials and between the above-mentioned dynamic mechanical properties of elastic modulus E′ and tan δ in each vulcanized elastomeric material, as long as the purpose of the present invention is met.

[0299] Table 4

[0300]

[0301] As can be clearly seen from Table 4, the values ​​of the ratios R1, R2, R5 and R6 are equal to or close to 1, indicating a homogeneous behavior between the second and third vulcanized elastomeric materials (i.e., between the rubber compound present in the radially outer part and the rubber compound present in the radially inner part of the shoulder region of tire 1) under both "hot" and "cold" conditions.

[0302] It can also be clearly seen from Table 4 that the "hot" values ​​of the ratios R3 and R4 of tan δ and the dynamic elastic modulus E' between the first vulcanized elastomeric material present in the central sub-portion of the radially outer portion of the tread band of tire 1 and the third vulcanized elastomeric material present in the radially inner portion indicate a sufficiently differentiated behavior between these materials, namely that the base portion of the tread band has a greater deformation and hysteresis behavior, while the central sub-portion of the radially outer portion of the tread band has a greater rigidity and less hysteresis behavior.

[0303] In this way and as described above, such a vulcanized elastomeric material allows the tire to achieve optimal “hot” handling and roadholding properties during travel in a straight line.

[0304] Finally, as can be clearly seen from Table 4, the "cold" values ​​of the ratios R7 and R8 of the dynamic elastic modulus E' and tan δ between the first vulcanized elastomeric material present in the central sub-portion of the radially outer portion of tyre 1 and the third vulcanized elastomeric material present in the radially inner portion, foreshadow a sufficiently differentiated behaviour between these materials, namely a greater deformation and hysteresis behaviour of the base portion of the tread band, whereas the central sub-portion of the radially outer portion of the tread band has greater rigidity and less hysteresis behaviour.

[0305] In this way and as described above, such a vulcanized elastomeric material allows to achieve optimal “cold” handling and roadholding properties of the tire during straight-line travel.

[0306] Tire outdoor testing

[0307] Seeking improved performance, the applicant used the Pirelli Diablo Rosso TM The IV 190 / 55ZR17 rear tire served as the basis for the comparative driving tests. This tire has proven to be and still is a highly regarded benchmark tire for sports users.

[0308] The choice of testing on the rear tires was considered particularly stringent because, during sport driving, the rear tires are subject to greater thermal stresses than the front tires.

[0309] Both the tyre according to the invention and the comparison tyre have a tread band of "cap-base" construction, with the difference being that the comparison tyre has a construction of two different vulcanized elastomeric materials, namely a first elastomeric material in the lateral sub-portions of the radially outer portion of the tread band and a second elastomeric material in the central sub-portion of the radially outer portion of the tread band and in the radially inner portion of the tread band.

[0310] The tire according to the invention has a construction of three different vulcanized elastomeric materials, two of which are in the radially outer part and one in the radially inner part, as described above with reference to Figure 2 shown.

[0311] The rubber compounds given in Table 2 and the mechanical properties given in Tables 3 and 4 were used to manufacture the radially inner and radially outer portions of a tread band of a supersport tyre for rear wheels of similar dimensions to those of the comparison tyre.

[0312] The tread bands of the cap-base type of the comparative tires were made of the two materials given in Table 5 below (the compositions were as previously indicated in Table 2, where applicable).

[0313] Table 5 (Comparison tires)

[0314]

[0315]

[0316] *phr of dry polymer without extender oil

[0317] Different test missions were carried out on a private track, testing grip and handling on both dry and wet surfaces by performing a series of manoeuvres. The driver's rating represents the average of the ratings performed in the various manoeuvres.

[0318] The test conditions on dry ground were as follows: Tire inflation pressure: 2.5 bar; Track asphalt temperature: 39°C; Air temperature: 18°C.

[0319] The test conditions on wet ground were as follows: Tire inflation pressure: 2.9 bar; Track asphalt temperature: 8°C; Air temperature: 8°C.

[0320] The tests were carried out using a "super sports" motorcycle model BMW S1000 R.

[0321] Tables 6 and 7 below summarize the scores given by the testers in the dry and wet tests, respectively, for the various types of performance required of the tires tested.

[0322] Furthermore, in dry tests, different groups of tyres according to the invention and of the comparative tyres were subjected both to a single lap test (columns 1 and 2 of Table 6) and to 20 laps of a track test (columns 3 and 4 of Table 6) in order to verify, in the second case, the performance degradation due to intensive use ("hard handling") simulating a race on a track or several training missions (approximately 100 km of travel).

[0323] Table 5 shows that for the tire according to the present invention, the symbol "=" is used to evaluate the same performance relative to the reference tire, and the symbol "+" is used to indicate improvement relative to the reference tire. As the performance improvement increases, the number of symbols "+" increases.

[0324] It should be noted that only the evaluations between columns 1 and 2 (single laps) and between columns 3 and 4 (after 20 laps) were homogeneous. In other words, the set of tyres used for the single lap evaluation was not the same set of tyres used for the race simulation test, and the single lap was not the first lap of the race simulation.

[0325] Table 6 (Test on dry ground)

[0326]

[0327] Table 7 (Test on wet ground - single lap)

[0328]

[0329]

[0330] It can be clearly seen from the evaluation results given in Tables 6 and 7 that the tire according to the present invention allows the desired dual purpose to be achieved, namely to improve and maintain the handling and performance of the tire for as long as possible under "hot" use conditions without compromising the handling and grip performance of the tire under the above-mentioned "cold" use conditions.

[0331] Surprisingly, the effect of improving and maintaining over time the handling and performance of the tyre under "hot" use conditions is achieved despite the use of a "soft" vulcanized elastomeric material in the radially inner portion of the tread band, apparently less suitable for this type of running conditions.

[0332] During the tests carried out, it was also noted that the lap times on the test track were significantly shorter with the tire according to the invention.

[0333] Various modifications may be made to the embodiments described in detail which still fall within the scope of protection of the invention as defined by the following claims.

Claims

1. A motorcycle tire (1), comprising an equatorial plane (XX) and a tread band (8), the tread band comprising: a) a radially outer portion (11), said radially outer portion comprising: a1) a central sub-portion (11a) arranged astride the equatorial plane (XX) of the tyre and made of a first vulcanized elastomeric material, and a2) a pair of lateral sub-portions (11b, 11c) located distally with respect to the equatorial plane (XX) of the tyre (1) and arranged on opposite sides of the central sub-portion (11a), the lateral sub-portions (11b, 11c) being made of a second vulcanized elastomeric material; wherein the dynamic elastic modulus (E') of the first vulcanized elastomeric material of the central sub-portion (11a) measured at a frequency of 10 Hz and 23° C. is greater than the dynamic elastic modulus (E') of the second vulcanized elastomeric material of the lateral sub-portions (11b, 11c) measured at a frequency of 10 Hz and 23° C.; wherein the first vulcanized elastomeric material of the central sub-portion (11a) and the second vulcanized elastomeric material of the lateral sub-portions (11b, 11c) have a respective dynamic elastic modulus (E') measured at a frequency of 10 Hz and at 23°C of between 5.2 MPa and 6.5 MPa, preferably between 5.8 MPa and 6.4 MPa; b) a radially inner portion (12) extending below said radially outer portion (11) of said tread band (8) along its entire axial extent, said radially inner portion (12) being made of a third vulcanized elastomeric material having a dynamic modulus of elasticity (E') measured at a frequency of 10 Hz and at 23° C. that is smaller than the dynamic modulus of elasticity (E') of said first vulcanized elastomeric material of said central sub-portion (11a) of said radially outer portion (11) of said tread band (8) and of said second vulcanized elastomeric material of said lateral sub-portions (11b, 11c) of said radially outer portion (11) of said tread band (8); wherein the ratio R1 between the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 100° C. of said second vulcanized elastomeric material of said lateral sub-portions (11 b, 11 c) of said radially outer portion (11) of said tread band (8) and the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 70° C. of said third vulcanized elastomeric material of said radially inner portion (12) of said tread band (8) is comprised between 0.8 and 1.2, preferably between 0.9 and 1.1; and wherein a ratio R2 between a tan δ of the second vulcanized elastomeric material of the lateral sub-portions (11b, 11c) of the radially outer portion (11) of the tread band (8) measured at a frequency of 10 Hz and 100°C and a tan δ of the third vulcanized elastomeric material of the radially inner portion (12) of the tread band (8) measured at a frequency of 10 Hz and 70°C is between 0.8 and 1.2, preferably between 0.9 and 1.

1.

2. The motorcycle tire (1) according to claim 1, wherein: The dynamic elastic modulus (E') of said first vulcanized elastomeric material of said central sub-portion (11a) of said radially outer portion (11) of said tread band (8) is comprised between 5.1 and 5.5 MPa, preferably between 5.2 and 5.4 MPa, measured at a frequency of 10 Hz and 70°C.

3. A motorcycle tyre (1) according to any one of the preceding claims, wherein: Said first vulcanized elastomeric material of said central sub-portion (11a) of said radially outer portion (11) of said tread band (8) has a tan delta measured at a frequency of 10 Hz and at 70°C comprised between 0.26 and 0.30, preferably between 0.27 and 0.

29.

4. A motorcycle tyre (1) according to any one of the preceding claims, wherein: Said second vulcanized elastomeric material of said lateral sub-portions (11b, 11c) of said radially outer portion (11) of said tread band (8) has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and 100°C comprised between 2.5 and 2.9 MPa, preferably between 2.6 and 2.8 MPa.

5. A motorcycle tyre (1) according to any one of the preceding claims, wherein: Said second vulcanized elastomeric material of said lateral sub-portions (11b, 11c) of said radially outer portion (11) of said tread band (8) has a tan delta measured at a frequency of 10 Hz and at 100°C comprised between 0.24 and 0.28, preferably between 0.25 and 0.

27.

6. A motorcycle tyre (1) according to any one of the preceding claims, wherein: Said third vulcanized elastomeric material of said radially inner portion (12) of said tread band (8) has a dynamic elastic modulus (E'), measured at a frequency of 10 Hz and 70°C, comprised between 2.5 and 2.9 MPa, preferably between 2.6 and 2.8 MPa.

7. Motorcycle tyre (1) according to any one of the preceding claims, wherein: Said third vulcanized elastomeric material of said radially inner portion (12) of said tread band (8) has a tan delta measured at a frequency of 10 Hz and at 70°C comprised between 0.25 and 0.29 MPa, preferably between 0.26 and 0.28 MPa.

8. A motorcycle tyre (1) according to any one of the preceding claims, wherein: Said first vulcanized elastomeric material of said central sub-portion (11a) of said radially outer portion (11) of said tread band (23) has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and at 23°C comprised between 6.0 and 6.5 MPa, preferably between 6.2 and 6.4 MPa.

9. A motorcycle tyre (1) according to any one of the preceding claims, wherein: Said first vulcanized elastomeric material of said central sub-portion (11a) of said radially outer portion (11) of said tread band (8) has a tan delta measured at a frequency of 10 Hz and at 23°C comprised between 0.40 and 0.44, preferably between 0.41 and 0.

43.

10. Motorcycle tyre (1) according to any one of the preceding claims, wherein: Said second vulcanized elastomeric material of said lateral sub-portions (11b, 11c) of said radially outer portion (11) of said tread band (8) has a dynamic elastic modulus (E') measured at a frequency of 10 Hz and at 23°C comprised between 5.5 and 6.0 MPa, preferably between 5.7 and 5.9 MPa.

11. Motorcycle tyre (1) according to any one of the preceding claims, wherein: Said second vulcanized elastomeric material of said lateral sub-portions (11b, 11c) of said radially outer portion (11) of said tread band (8) has a tan delta measured at a frequency of 10 Hz and at 23°C comprised between 0.66 and 0.70, preferably between 0.67 and 0.

69.

12. Motorcycle tyre (1) according to any one of the preceding claims, wherein: Said third vulcanized elastomeric material of said radially inner portion (12) of said tread band (8) has a dynamic elastic modulus (E'), measured at a frequency of 10 Hz and at 23°C, comprised between 4.0 and 5.0 MPa, preferably between 4.2 and 4.5 MPa.

13. A motorcycle tyre (1) according to any one of the preceding claims, wherein: Said third vulcanized elastomeric material of said radially inner portion (12) of said tread band (8) has a tan delta measured at a frequency of 10 Hz and at 23°C comprised between 0.49 and 0.53 MPa, preferably between 0.50 and 0.52 MPa.

14. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The ratio R3 between the tan δ measured at a frequency of 10 Hz and 70°C of the first vulcanized elastomeric material of the central sub-portion (11a) of the radially outer portion (11) of the tread band (8) and the tan δ measured at a frequency of 10 Hz and 70°C of the third vulcanized elastomeric material of the radially inner portion (12) of the tread band (8) is between 0.5 and 1.2, preferably between 0.7 and 1.

0.

15. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The ratio R4 between the dynamic elastic modulus (E') of the first vulcanized elastomeric 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 and the dynamic elastic modulus (E') of the third vulcanized elastomeric material of the radially inner portion (12) of the tread band (8) measured at a frequency of 10 Hz and 70°C is between 1.3 and 2.0, preferably between 1.5 and 1.

8.

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

5.

17. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The ratio R6 between the tan δ of the second vulcanized elastomeric material of the lateral sub-portions (11b, 11c) of the radially outer portion (11) of the tread band (8) measured at a frequency of 10 Hz and 23°C and the tan δ of the third vulcanized elastomeric material of the radially inner portion (12) of the tread band (8) measured at a frequency of 10 Hz and 23°C is between 1.1 and 1.6, preferably between 1.2 and 1.

5.

18. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The ratio R7 between the dynamic elastic modulus (E') measured at a frequency of 10 Hz and 23°C of the first vulcanized elastomeric material of the central sub-portion (11a) 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 23°C of the third vulcanized elastomeric material of the radially inner portion (12) of the tread band (8) is between 1.2 and 1.8, preferably between 1.3 and 1.

7.

19. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The ratio R8 between the tan δ of the first vulcanized elastomeric 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 23°C and the tan δ of the third vulcanized elastomeric material of the radially inner portion (12) of the tread band (8) measured at a frequency of 10 Hz and 23°C is between 0.6 and 1.1, preferably between 0.7 and 1.

0.

20. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The ratio R9 between the dynamic elastic modulus (E') of the third vulcanized elastomeric material of the radially inner portion (12) of the tread band (8) measured at a frequency of 10 Hz and 23°C and the dynamic elastic modulus (E') of the same vulcanized elastomeric material measured at a frequency of 10 Hz and 70°C is between 1.2 and 2.0, preferably between 1.4 and 1.

9.

21. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The ratio R10 between the tan δ measured at a frequency of 10 Hz and 23° C. of said third vulcanized elastomeric material of said radially inner portion (12) of said tread band (8) and the tan δ measured at a frequency of 10 Hz and 70° C. of the same vulcanized elastomeric material is comprised between 1.5 and 2.4, preferably between 1.7 and 2.

1.

22. Motorcycle tyre (1) according to any one of the preceding claims, wherein: The tire has a transverse curvature ratio equal to or greater than about 0.30, preferably between 0.30 and 0.35.

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