Motorcycle front tyre

Abstract

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

Description

TECHNICAL FIELD

[0001] The present application relates to a motorcycle front tyre.

[0002] In particular, the present application relates to a motorcycle tyre for the "super sport" and / or "hyper sport" submarket having a large displacement (for example, 600 cm 3 or 1000 cm 3 or more) and / or high power (for example, 200 horse power or more), such motorcycle tyres being also used on the track. BACKGROUND

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

[0004] In recent years, a trend has been observed on the market to launch motorcycles with high power super sport or hyper sport. Indeed, there are on the market, for example, road motorcycles with a displacement of 1000 cm 3 and more and a power of 200 horse power or even more.

[0005] The Applicant has noted that there is an increasing demand for high performance tyres for motorcycles that require sporty driving (for example, to be achieved on the track) and for year-round road use of the motorcycle, in particular in adverse weather conditions.

[0006] In this regard, the Applicant has in particular observed that users have found a recent trend to combine in tyres fitted on super sport motorcycles the driving ability and performance in extreme handling conditions and speed conditions on dry and / or hot surfaces (hereinafter also referred to as "hot" use conditions) and the driving ability and road holding in wet or damp conditions and / or in cold weather or in non-optimal road surface conditions (hereinafter also referred to as "cold" use conditions), and at the same time keeping the performance of the tyre as constant as possible over time.

[0007] Satisfying these mutually conflicting requirements with a single pair of tyres is a particularly challenging task, in the case where different types of action are usually adopted for each of the above requirements, adopting solutions that are suitable for a specific problem but are in contrast with the other problems.

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

[0009] To improve the grip of the tyre, it is possible to make the tread band with so-called soft vulcanised elastomeric materials which better adapt to the roughness of the road surface by imitating the irregular profile of the road surface. These vulcanised elastomeric materials are typically characterised by a low modulus of elasticity and / or a high hysteresis.

[0010] However, the Applicant has found that a vulcanised elastomeric material which is too soft causes a decrease in the stability of the tyre when travelling along straight routes and a reduction in the mileage of the tyre.

[0011] To overcome the above-mentioned problems, tyres have been proposed which are made with different vulcanised elastomeric materials. Typically, the vulcanised elastomeric material is softer at the shoulders and less soft at the crown.

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

[0013] However, with this configuration of the tread band, the Applicant has observed that, in "cold" conditions of use, the drivability and performance of the tyre tend to decrease, especially in the case of road use on wet ground, seriously compromising the performance of the tyre.

[0014] To attempt to satisfy the above-mentioned contradictory requirements with a single pair of tyres, tyres have also been proposed which have a tread band made with different vulcanised elastomeric materials, typically using a vulcanised elastomeric material with a higher content of carbon black filler at the shoulders and a plurality of vulcanised elastomeric materials with a higher content of white filler at the crown and at the intermediate annular portion of the tread band.

[0015] In combination with the appropriate distribution and arrangement of the grooves of the tread band at the interface of the different compositions of vulcanised elastomeric material, everything is for example as described in the patent application WO 2019 / 082012 in the name of the present Applicant.

[0016] In the constant improvement process of motorcycle tyres, in particular front tyres, the Applicant has set itself the double task of maintaining the drivability and performance of the front tyre at an excellent level in "hot" conditions of use, while improving the drivability and grip performance of the front tyre in the aforementioned "cold" conditions of use, both on dry ground and on wet ground.

[0017] The Applicant has found that this double task is possible by adopting a so-called "crown base" tread band configuration and by using a vulcanised elastomeric material which has appropriate dynamic mechanical properties both in "cold" and "hot" conditions of use of the tyre.

[0018] In particular, the Applicant has found that, for this purpose, it is necessary to adopt at the same time the following provisions:

[0019] i) the construction of the radially outer portion of the tread band of the tyre comprises a central annular portion arranged astride the equatorial plane of the tyre and a pair of lateral annular portions arranged at axially opposite sides of the central annular portion;

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

[0021] iii) a material having specific mechanical stiffness characteristics related to the dynamic elastic modulus E' in the "cold" conditions of use of the tyre and specific hysteresis mechanical characteristics related to tandelta in the "hot" conditions of use of the tyre is used as the first vulcanized elastomeric material and as the second vulcanized elastomeric material.

[0022] In this regard, the Applicant has in fact found that, in order to achieve the above-mentioned dual task, it is necessary to evaluate the dynamic mechanical characteristics of the vulcanized elastomeric materials used to make the different portions of the tread band in a differentiated manner, for each elastomeric material, in specific stress and temperature conditions related to the actual conditions of use of each elastomeric material, which is subjected to different types of stress and temperature during the use of the front tyre, depending on the position of the material in the tread band.

[0023] As regards the "cold" use of the tyre, the Applicant has in particular found that the dynamic mechanical characteristic that predicts the behaviour of the front tyre in such conditions of use is the dynamic elastic modulus E', measured at 10 Hz frequency and at 23°C, for all the elastomeric materials that make up the tread band.

[0024] Conversely, as regards the "hot" use of the front tyre, the Applicant has found that the dynamic mechanical characteristic that predicts the behaviour of the tyre in such conditions of use is tandelta, measured at 10 Hz frequency and at 23°C, for the first vulcanized elastomeric material of the radially inner portion of the tread band and of the central annular portion of the radially outer portion of the tread band, and at 10 Hz frequency and at 70°C, for the second vulcanized elastomeric material of the lateral annular portions of the radially outer portion of the tread band.

[0025] - at 10 Hz frequency and at 23°C, for the first vulcanized elastomeric material of the radially inner portion of the tread band and of the central annular portion of the radially outer portion of the tread band, tandelta is measured; and

[0026] - at 10 Hz frequency and at 70°C, for the second vulcanized elastomeric material of the lateral annular portions of the radially outer portion of the tread band, tandelta is measured.

[0027] The Applicant has therefore surprisingly found that, by keeping the following dynamic mechanical characteristics close to the value of 1, it is possible to simultaneously achieve the desired preservation of the driving and grip performance of the front tyre in the above-mentioned "hot" conditions of use and the improvement of the driving and grip performance in the above-mentioned "cold" conditions of use:

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

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

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

[0031] The present application therefore relates to a motorcycle front tyre comprising an equatorial plane and a tread band having an overall axial extension,

[0032] wherein the tread band comprises:

[0033] a) a radially outer portion comprising:

[0034] al) a central annular portion arranged astride the equatorial plane of the tyre and made of a first vulcanized elastomeric material, and

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

[0036] b) a radially inner portion underlying the radially outer portion of the tread band and extending along the entire axial extension of the tread band, made of said first vulcanized elastomeric material;

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

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

[0039] Basically, in the front tyre according to the present application, it seems that the following characteristics are effectively merged:

[0040] i) the ground "imitation" property of the front tyre, which is related to the hysteresis property in "hot" use conditions; and

[0041] ii) the uniformity property of the response of the front tyre to the stresses to which it is subjected in "cold" use conditions.

[0042] The Applicant has found that the fusion of these properties allows the motorcycle front tyre, especially in the "super sport" and / or "super sport" sub-markets, to maintain the driving and grip performance in dry and / or hot ground conditions over time, while improving the driving and grip performance in "cold" use conditions, in wet or damp conditions and / or in cold weather or in non-optimal road surface conditions.

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

[0044] This result appears surprising, since the use of a relatively "hard" vulcanized elastomeric material in the radially inner portion of the tread band appears not only unsuitable for providing adequate performance in such use conditions, but even liable to cause, on the contrary, a sharp drop in the performance of the front tyre.

[0045] On the contrary, the Applicant has found that the substantially uniform dynamic and hysteresis behaviour of the tread band in the "hot" use conditions of the front tyre allows the "imitation" property of the tyre to be maintained, thus avoiding performance drops and premature wear phenomena.

[0046] On the contrary, and again without wishing to be bound to any explanatory theory, the Applicant believes that, in "cold" use conditions, the front tyre as defined above has a substantially uniform dynamic behaviour of the tread band as a whole in such use conditions.

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

[0048] Advantageously, therefore, the front tyre according to the present application allows not only the optimal driving and grip performance to be maintained in dry and / or hot ground use conditions, typical of track use conditions, but also improved driving and grip performance to be achieved in "cold" use conditions, typical of road use conditions.

[0049] From a practical point of view, this translates into the particularly appreciated advantage for the user of not necessarily having to change the front tyre when switching from track use to road use, and vice versa.

[0050] In the present specification and in the following claims, unless otherwise indicated, all numerical entities expressing amounts, parameters, percentages, etc. are to be understood as being preceded by the term "about" in all cases. Moreover, except for those specifically indicated in the following text, all ranges of numerical entities include all possible combinations of the maximum and minimum numerical values and all possible intermediate ranges.

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

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

[0053] The term "phr" (abbreviation for parts per hundred parts of rubber) means the parts by weight of a given component of the elastomer compound per 100 parts by weight of elastomer polymer, the elastomer polymer being considered excluding possible plasticizing extender oils.

[0054] The term "elastomeric material", "rubber", "elastomer polymer" or "elastomer" is used to mean a material comprising a vulcanizable natural or synthetic polymer and a reinforcing filler, in which such material, after vulcanization at room temperature, can undergo a deformation caused by a force and is able to quickly and strongly return to the substantially original shape and dimensions after the deformation force has been eliminated (according to the definition of the standard terms relating to rubber according to ASTM standard D1566-11).

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

[0056] The term "compound" or "elastomer compound" is used to mean a mixture obtained by mixing, and possibly heating, at least one elastomer polymer and at least one additive typically used for preparing tire compounds.

[0057] The term "vulcanizable compound" or "vulcanizable elastomer compound" is used to mean an elastomer mixture ready for vulcanization, which can be obtained by incorporating in the elastomer compound all the additives, including vulcanization additives.

[0058] The term "vulcanized elastomeric material" is used to mean a material obtained by vulcanization of a vulcanizable elastomer compound.

[0059] The term "vulcanization" is used to mean a crosslinking reaction in natural or synthetic rubber induced by crosslinking agents, typically sulfur-based.

[0060] The term "vulcanizing agent" is used to refer to compounds that can transform natural or synthetic rubber into a resilient and robust material by forming a three-dimensional network of intermolecular and intramolecular bonds. Typical vulcanizing agents are sulfur-based compounds, such as elemental sulfur, polymeric sulfur, and sulfur donors, such as bis[(trialkoxysilyl)propyl] polysulfides, thiuram, dithiodimorpholine, and caprolactam disulfides.

[0061] The term "vulcanization accelerator" is used to refer to compounds that can reduce the duration of vulcanization treatment and / or lower the operating temperature, such as TBBS, sulfenamides, thiazoles, dithiophosphoric acids, dithiocarbamates, guanidines, and sulfur donors such as thiuram.

[0062] The term "vulcanization activator" is used to refer to compounds that can further promote vulcanization, allowing it to occur in a shorter time and possibly at a lower temperature. An example of an activator is the stearic acid-zinc oxide system.

[0063] The term "vulcanization retardant" is used to refer to compounds that can delay the onset of vulcanization and / or inhibit undesirable side reactions, such as N-(cyclohexylthio)phthalimide (CTP).

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

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

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

[0067] The term "curvature ratio" is used to represent the ratio between the distance (also indicated by an "arrow") contained in the cross section of the tire at the radially highest point of the tread strip and the maximum width of the tire's radial section, and the maximum width of the tire.

[0068] The term “axial extension” of the tread belt or a portion thereof is used to describe the extension of the outermost radial profile of the tread belt or a portion thereof in a cross section taken in a plane containing the axis of rotation of the tire.

[0069] The terms “semi-axial extension” of the tread pattern, tread band, or a portion thereof are used to describe the extension of the radial outermost profile of the tread band or a portion thereof from the equatorial plane toward the outermost axial end of the tire in a cross section taken in a plane containing the axis of rotation of the tire.

[0070] The term "equatorial plane" in tires refers to the plane that is perpendicular to the tire's axis of rotation and divides the tire symmetrically into equal parts.

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

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

[0073] The terms “radial” and “axial”, as well as the expressions “radial in / out” and “axial in / out”, are used by reference to directions substantially parallel to the equatorial plane of the tire and substantially perpendicular to the equatorial plane of the tire, respectively; that is, by reference to directions substantially perpendicular to the axis of rotation of the tire and substantially parallel to the axis of rotation of the tire, respectively.

[0074] The terms “circumferential” and “circumferentially” are used with reference to the circumferential extension direction of the tire, that is, with reference to the rolling direction of the tire, which corresponds to a direction located on a plane that coincides with or is substantially parallel to the equatorial plane of the tire.

[0075] The term “circumferential extension” for a tire, tread belt or a portion thereof is used to describe the planar extension of the outermost radial surface of a tire, tread belt or a portion thereof in a plane tangent to the tire.

[0076] The terms "inner axis" and "outer axis" refer to positions closer to and further away from the equatorial plane relative to the reference element, respectively.

[0077] The term "radial carcass structure" is used to describe a carcass structure comprising multiple reinforcing cords, each of which is oriented in a substantially axial direction within the crown portion of the tire. These reinforcing cords may be incorporated into a single carcass ply or into several carcass ply (preferably two) that are radially stacked on top of each other.

[0078] The term "basic axial direction" is used to refer to a direction whose angle of inclination relative to the equatorial plane of the tire is between 60° and 90°.

[0079] The term "basic circumferential direction" is used to describe a direction whose orientation relative to the equatorial plane of the tire is between 0° and 20°.

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

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

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

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

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

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

[0086] The term "void-to-rubber ratio of an annular portion" or "void-to-rubber ratio of an annular segment", or in general "void-to-rubber ratio", is used to indicate the ratio between the total surface of the grooves of an annular portion or annular segment and the total surface of the annular portion itself or of the annular segment itself.

[0087] The term "substantially groove-free" in relation to a portion of the tread band of a tyre is used to indicate that the "void-to-rubber ratio", as defined above, in the portion of the tread band considered is very close to or substantially equal to zero, for example, its value is less than 0.2%.

[0088] The term "pitch" of a tyre is used to indicate a group of grooves and solid portions arranged to form a portion of a pattern which repeats substantially identical and uninterrupted along the circumferential development of the tread band. Along the circumferential development of the tread band, the pitches can have different circumferential lengths and can be circumferentially offset from one another on opposite sides of the equatorial plane of the tyre.

[0089] The expression "module" relating to a tread band, in particular to a tread pattern, is used to indicate a portion of tread pattern which repeats identically in succession along the entire circumferential extension of the tread band itself. While maintaining the same pattern configuration, these modules can still have different circumferential lengths and / or have respective portions positioned on opposite sides of the equatorial plane of the tyre and circumferentially offset along the circumferential development of the tyre itself.

[0090] In the second case, the tyre comprises "pitches" which are circumferentially offset from one another on opposite sides of the equatorial plane.

[0091] The application can have one or more of the preferred features given below in the one or more of the above aspects, which can be combined with one another, if desired, according to the needs of application.

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

[0093] In this way, it is possible to advantageously provide the tread band with optimal behavior homogeneity characteristics in "cold" use conditions of the front tyre, in which there is a significant improvement in the driving performance and road holding performance.

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

[0095] In this way, it is possible to advantageously provide the tread band with optimal ground "imitation" characteristics in "hot" use conditions of the front tyre, while maintaining or further improving its driving performance and road holding performance in these use conditions.

[0096] In fact, from the perspective of its "hot" deformation capability, the shoulder region of the tread band of the front tyre is formed by a vulcanized elastomeric material which is substantially "homogeneous" from the perspective of its road behaviour.

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

[0098] In this way, it is possible to advantageously provide the radially inner portion of the tread band with sufficient stiffness and support characteristics in "hot" use conditions of the front tyre.

[0099] Preferably, the dynamic elastic modulus E' of the second vulcanized elastomeric material of the lateral annular portion of the radially outer portion of the tread band, measured at 10 Hz frequency and at 23°C, is comprised between 5.2 MPa and 6.5 MPa, more preferably between 5.6 MPa and 6.0 MPa.

[0100] Advantageously, this preferred feature contributes to optimizing and substantially maintaining or improving the driving behaviour and performance of the tyre on dry and / or hot surfaces during the "hot" use conditions of the front tyre during driving along a curve.

[0101] Preferably, the dynamic elastic modulus E' of the second vulcanized elastomeric material of the lateral annular portion of the radially outer portion of the tread band, measured at 10 Hz frequency and at 23°C, is comprised between 5.2 MPa and 6.5 MPa, more preferably between 5.6 MPa and 6.0 MPa.

[0102] Advantageously, this preferred feature contributes to achieving the optimal homogeneity of the tread band of the front tyre to improve the driving behaviour and performance of the tyre in "cold" use conditions.

[0103] Preferably, the dynamic elastic modulus E' of the second vulcanized elastomeric material of the lateral annular portion of the radially outer portion of the tread band, measured at 10 Hz frequency and at 23°C, is comprised between 5.2 MPa and 6.5 MPa, more preferably between 5.6 MPa and 6.0 MPa.

[0104] Advantageously, this preferred feature contributes to achieving the optimal "mimic" characteristics of the tread band on the ground in "hot" use conditions of the front tyre, while maintaining or further improving the driving behaviour and road holding performance in these use conditions.

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

[0106] Preferably, the white reinforcing filler comprises an inorganic material in an amount 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%, by total weight of the reinforcing filler, the inorganic material being selected from the group consisting of silica, alumina, silicates, hydrotalcites, calcium carbonate, kaolin, titanium dioxide and mixtures thereof.

[0107] Advantageously, this preferred feature contributes to achieving optimal wet grip properties in "cold" use conditions of the front tire.

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

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

[0110] Advantageously, this preferred feature contributes to achieving optimal grip properties in "hot" use conditions of the front tire.

[0111] Preferably, the central annular portion of the radially outer portion of the tread band extends transversely along from 5% to 25% of the half-axial extension of the tread band, preferably along from 10% to 20% of the half-axial extension of the tread band.

[0112] In this way, it can be advantageous to have optimal stiffness and road holding properties in "cold" use conditions of the front tire.

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

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

[0115] In preferred embodiments, each of the lateral annular portions of the radially outer portion of the tread band is arranged axially outside and adjacent to the central annular portion, to define an interface separating the central annular portion and the lateral annular portions in the axial direction.

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

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

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

[0119] In this way, it can be advantageously possible to achieve a gradual transition between the first vulcanized elastomeric material and the second vulcanized elastomeric material in the tread band in the axial direction, to achieve the optimal dynamic mechanical properties and behavior homogeneity of the front tire.

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

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

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

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

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

[0125] In this way, it can be advantageously possible to optimize the drivability and grip performance of the front tire in wet or damp conditions, thanks to the adhesion capacity of the first vulcanized elastomeric material of the central annular portion of the radially outer portion of the tread band.

[0126] Preferably, the lateral annular portions of the radially outer portion of the tread band each comprise a first lateral annular sub-portion proximal to the equatorial plane of the tyre and a second lateral annular sub-portion distal to the equatorial plane.

[0127] Preferably, the tyre comprises a plurality of grooves formed in the first lateral annular sub-portion of said lateral annular portions of the radially outer portion of the tread band.

[0128] Applicants have found through experiments that, thanks to these features, there is a significant synergistic match between the construction of the tread pattern in the portion provided with grooves and the stiffness mechanical characteristics of the tread band having a "crown base" structure as defined above, thus achieving the best drivability and performance of the tyre on wet and / or cold ground.

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

[0130] In this way, it can be advantageous to optimize the drivability and grip performance of the front tyre on wet or damp surfaces, since the lateral annular portions of the radially outer portion of the tread band, in particular the first lateral annular sub-portions thereof, are able to expel the water present below the tyre ground contact area in the tread band area most frequently used during the "cold" use conditions of the front tyre.

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

[0132] In this way, it can be advantageous to give the tread band sufficient stiffness without limiting its draining capacity.

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

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

[0135] In this way, it can be advantageous to achieve the best compromise between the drivability and grip performance of the front tyre in "cold" use conditions, in wet or damp conditions, and the drivability and grip performance in "hot" use conditions.

[0136] In a preferred embodiment, the aforesaid plurality of grooves defines, in each first lateral annular sub-portion of the lateral annular portion of the radially outer portion of the tread band, a first annular segment arranged axially outward of the central annular portion and adjacent to the central annular portion, the void rubber ratio in the aforesaid first annular segment increasing along the semi-axial extension of the tread band and moving away from the equatorial plane of the tyre.

[0137] Preferably, the aforesaid first annular segment extends laterally along 5-25% of the semi-axial extension of the tread band, more preferably along 10-20% of the semi-axial extension of the tread band, from an end of the lateral annular portion of the radially outer portion of the tread band located proximally to the equatorial plane, in other words from a circumferential line defined by the intersection between the plane passing through the interface and the radially outer surface of the tread band, said proximal end separating the central annular portion and the lateral annular portion of the radially outer portion of the tread band in the axial direction.

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

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

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

[0141] In this way, it can be advantageous to optimize the driving behavior and grip performance of the front tyre in wet or humid conditions thanks to the synergistic matching between the configuration of the tread pattern and the mechanical hysteresis properties of the second vulcanized elastomeric material of the lateral annular portion of the radially outer portion of the tread band.

[0142] In particular, in the "cold" use conditions of the front tyre, the lateral annular portion of the radially outer portion of the tread band is able to effectively expel the water present below the tyre ground contact area in the region of the tread band most commonly used during travel along straight routes and, often, when driving along curves with low camber angles, while the mechanical hysteresis properties of the tread band allow a homogeneous response to the stresses to which the tyre is subjected in these use conditions.

[0143] In a preferred embodiment, the plurality of grooves defines, in each first lateral annular sub-portion of the lateral annular portion of the radially outer portion of the tread band, a void-to-rubber ratio in the second annular segment arranged axially outwardly of the first annular segment and adjacent to the first annular segment, said void-to-rubber ratio decreasing along the axial extension of the tread band and moving away from the equatorial plane of the tyre.

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

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

[0146] Advantageously, in this preferred embodiment of the application, the value of the void-to-rubber ratio gradually decreases moving away from the equatorial plane of the tyre, which allows to exploit the hysteresis properties of the second vulcanized elastomer in the case of handling conditions and high camber angles that can be reached during the race / on the track under hot conditions.

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

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

[0149] In this way, it is possible to advantageously optimize the driving performance and grip performance of the tyre in "hot" conditions of use, i.e. in the absence of wet or damp surfaces, when the tyre is driven along a curve, often with a high camber angle.

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

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

[0152] In this way, it can be advantageously optimized the driving behavior and the grip performance of the tyre along a curve when driven in "hot" conditions of use and therefore in the absence of wet or damp surfaces, in which driving is often carried out with a higher camber angle.

[0153] Preferably, the transverse curvature ratio of the motorcycle front tyre of the present application is equal to or greater than 0.35 and equal to or less than 0.50, more preferably equal to or greater than 0.39 and equal to or less than 0.45, even more preferably equal to or greater than 0.40 and equal to or less than 0.44. BRIEF DESCRIPTION OF DRAWINGS

[0154] Further features and advantages of the present application will become more apparent from the following description of some preferred embodiments thereof given, by way of illustration and non-limitation, with reference to the attached drawings.

[0155] The drawings are schematic and not to scale.

[0156] In the drawings:

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

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

[0159] Figure 3 is a graph showing the trend of the void rubber ratio along the half-axial extension of the front tyre of Figure 1

[0160] Figure 4 is a schematic plan view of a portion of the tread band of the front tyre of Figure 1 DETAILED DESCRIPTION

[0161] In the drawings, reference number 1 as a whole indicates a front tyre for a motorcycle wheel according to a preferred embodiment of the present application. This relates to a tyre which is preferably intended for use on a motorcycle rear wheel of a super sport motorcycle with large displacement (for example, 600 cc) of the "super sport" and "super sport" sub-markets.

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

[0163] The tyre 1 comprises a carcass structure 2 formed by at least one carcass layer 3 comprising a plurality of reinforcing elements (cords). In the illustrated embodiment, there are two carcass layers 3. Figure 1

[0164] The carcass structure 2 is typically coated on its inner wall with a sealing layer or so-called “liner”, mainly consisting of a layer of airtight elastomeric material, which is adapted to ensure the airtight seal of the tyre itself once inflated.

[0165] The reinforcing elements comprised in the carcass layer 3 preferably comprise textile cords made of a fibrous material.

[0166] The fibrous material used to make the cords can be made of fibres of natural or synthetic origin, selected from among rayon, lyocell, polyesters (for example, PEN, PET, PVA), aramids (for example, aramid such as Kevlar®), these fibres can be alone or mixed. More particularly, the fibrous material used to make the cords is preferably selected from among polyesters, rayon, lyocell, aramids or mixed materials formed by two or more of the above-mentioned materials.

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

[0168] The at least one carcass layer 3 is shaped according to a substantially toroidal configuration and is engaged with at least one toroidal reinforcing structure through its opposite circumferential edges 3a.

[0169] In particular, the opposite lateral edges 3a of the at least one carcass layer 3 can be turned up around the toroidal reinforcing structures, each comprising one or more metal toroidal bead cores 4 and a conical elastomeric filler 5, which occupies the space defined between the carcass layer 3 and the corresponding turned-up lateral edge 3a of the carcass layer 3.

[0170] The tyre areas comprising the bead cores 4 and the fillers 5 form so-called beads 9, which are intended to anchor the tyre 1 on the corresponding mounting rim (not shown).

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

[0172] A belt structure 6 is applied in a circumferential manner on the carcass structure 2 at a radially outer position, comprising at least one belt layer 6a typically formed by cords coated with rubber.

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

[0174] Preferably, the belt layer 6a, commonly referred to as "zero degree", can comprise axially adjacent turns of a single cord or comprise a rubber-coated fabric band of axially adjacent cords.

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

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

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

[0178] In an embodiment not shown, the belt structure 6 can be constituted by at least two radially superimposed layers. The layers are arranged so that the cords of a first belt layer are oriented obliquely with respect to the circumferential direction of the tyre, while the cords of a second layer also have an oblique orientation, but substantially symmetrically crossed with respect to the cords of the first layer.

[0179] A tread band 8 is superimposed in a circumferential manner on the belt structure 6, on which, after the moulding operation which simultaneously vulcanizes the tyre, longitudinal and transverse grooves are typically formed, arranged to define the desired tread pattern.

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

[0181] As Figure 4 Better shown, the tread pattern comprises a module 15 repeated along the circumferential development direction of the tyre 1.

[0182] In Figure 4 The preferred embodiment of the front tyre 1 shown, the module 15 comprises 2 pitches P mutually offset in the circumferential direction on opposite sides of the equatorial plane X-X of the tyre 1.

[0183] In the case where the tyre is intended to be mounted on the front wheel of a motorcycle, such as one purpose of the present application, the above-mentioned module 15 is repeated at least 10 times along the circumferential development of the tyre 1. Preferably at least 12 times, for example 14 times.

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

[0185] Preferably, the tread pattern comprises a series of circumferential second grooves 14 interposed between the first grooves 13 along the circumferential direction and preferably tapering along a direction opposite to the preferred rolling direction F of the tyre 1.

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

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

[0188] The tyre 1 can comprise a pair of sidewalls 10 laterally applied to the carcass structure 2 on opposite sides.

[0189] The tyre 1 has a section height H, measured on the equatorial plane X-X, between the top of the tread band 8 and between the fitting diameter passing through the beads of the tyre 1 (identified by the reference line r).

[0190] The tyre 1 also has a maximum width C of cross 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 (measured on the equatorial plane of the tyre 1) of the top of the tread band 8 from a line passing through the ends E of the tread band 8 itself and the aforesaid maximum width C. The axially opposite ends E of the tread band 8 can be formed by corners.

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

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

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

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

[0195] In a preferred embodiment, when the tyre 1 has a considerable height of the sidewall 10, the tyre 1 allows to have better performances, for example a value of the sidewall height ratio (H-f) / H equal to or greater than 0.3, more preferably equal to or greater than 0.35.

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

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

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

[0199] a1) a central annular portion L1 arranged astride the equatorial plane X-X of the tyre 1, and

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

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

[0202] In the preferred embodiment illustrated in the attached drawings, the tread band 8 comprises a radially inner portion 12 which extends below the radially outer portion 11 of the tread band 8 and along the entire axial extension of the tread band.

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

[0204] Preferably, the central annular portion LI of the tread band 8 has an axial extension LI which extends laterally along 5-25% of the half-axial extension L / 2 of the tread band 8, more preferably along 10-20% of the half-axial extension of the tread band 8.

[0205] Preferably, the lateral annular portions L2, L3 of the tread band 8 have respective axial extensions which extend laterally along 75-95% of the half-axial extension L / 2 of the tread band 8, more preferably along 80-90% of the half-axial extension of the tread band 8.

[0206] Preferably and as Figure 4 Better shown, the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 each comprise a first lateral annular sub-portion L2', L3' located proximally with respect to the equatorial plane X-X of the tyre 1 and a second lateral annular sub-portion L2", L3" located distally with respect to the equatorial plane X-X of the tyre 1.

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

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

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

[0210] The intersection between the plane passing through the interface 16 and the radially outer surface of the tread band 8 defines, on opposite sides of the equatorial plane X-X, a pair of circumferential lines 17, 18 (see Figure 3 and Figure 4 ), which identify the end portions of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 located proximal to the equatorial plane X-X.

[0211] Preferably, the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8, and therefore the circumferential lines 17, 18, are arranged at a distance from the equatorial plane X-X of the tyre 1 (as mentioned above), which is at least 10% of the half-axial extension L / 2 of the tread band 8.

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

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

[0214] Preferably, the lateral annular portions L2, L3 of the tread band 8 are also formed in one piece, for example by laying a continuous circumferential turn of at least one continuous elongated element of the second vulcanized elastomeric material mentioned above.

[0215] In this way and as mentioned above, a pair of interfaces 16 between the first vulcanized elastomeric material and the second vulcanized elastomeric material is defined in the radially outer portion 11 of the tread band 8 and located on opposite sides of the equatorial plane X-X of the tyre 1 and of the central annular portion L1.

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

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

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

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

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

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

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

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

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

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

[0226] Therefore, the X axis represents the distance (in mm) with respect to the equatorial plane X-X and the Y axis represents the void rubber ratio.

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

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

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

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

[0231] The "mobility" characteristics of these solid portions are advantageously adapted to "heat" the second vulcanized elastomeric material in "cold" conditions of use of the tyre 1 and have significantly improved performance in these conditions of use.

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

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

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

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

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

[0237] Preferably and as Figure 3 Better shown, the grooves 13, 14 define, in each first lateral annular sub-portion L2', L3' of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8, arranged axially outer to the first annular segment A and adjacent to the same, a void-to-rubber ratio which decreases along the axial extension of the tread band 8 and moving away from the equatorial plane X-X of the tyre 1 starting from the first annular segment A.

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

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

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

[0241] Preferably, the second lateral annular sub-portion L2", L3" of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 extends laterally for 10-55% of the half-axial extension L / 2 of the tread band 8 of the tyre 1, more preferably for 20-45% of the half-axial extension of the tread band.

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

[0243] The compound used for the different portions of the tread band 8 and for the other semi-processed products forming the tyre 1 comprises at least one elastomeric diene polymer (al).

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

[0245] According to one embodiment, said at least one elastomeric diene polymer (al) can be selected, for example, from the elastomeric diene polymers typically used in elastomeric compositions capable of being crosslinked with sulphur (vulcanized), which are particularly suitable for the production of tyres, i.e. from elastomeric polymers or copolymers having unsaturated chains, having a glass transition temperature (Tg) typically lower than 20°C, preferably ranging from 0°C and -110°C. These polymers or copolymers can be of natural origin or can be obtained by solution, emulsion or gas-phase polymerization of one or more conjugated dienes, optionally mixed with at least one comonomer selected from monovinylarenes and / or polar comonomers.

[0246] For the tread rubber compound, polybutadiene (BR) and / or styrene-butadiene polymers (SBR) are preferably used, either as such or in mixtures, for example SSBR (styrene butadiene elastomers from solution).

[0247] Preferably, the styrene-butadiene polymers (SBR) can be present in the rubber compound of the present application, in particular in the tread rubber compound, in variable amounts ranging from about 50 phr to 100 phr, more preferably from 70 phr to 100 phr.

[0248] Advantageously, polybutadiene (BR) can be absent or can be included in the rubber compound of the present application, in particular in the tread rubber compound, in amounts ranging from about 0 phr to 40 phr, more preferably from about 10 phr to 30 phr.

[0249] Preferably, the styrene-butadiene polymers can be obtained by solution polymerization and generally comprise styrene in amounts ranging from about 10% to 40% by weight, preferably from about 15% to 30%.

[0250] Preferably, the styrene-butadiene polymers can have a low molecular weight, with an average molecular weight Mn lower than 200.000 g / mol, preferably comprised between 150.000 g / mol and 200.000 g / mol.

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

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

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

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

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

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

[0257] In this way, it is possible to advantageously achieve a rapid warming up of the tread band 11 of the tyre 1 and an excellent grip on different road conditions.

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

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

[0260] Preferably, the carbon black is selected from carbon black having a surface area not less than 20 m 2 / g (preferably greater than 50 m 2 / g) (determined by STSA - Statistical Thickness Surface Area according to ISO 18852:2005).

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

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

[0263] In this way, it can be advantageous to optimize the value of the dynamic elastic modulus E' of the second elastomeric material as a function of the expected temperature values during the use of the tyre 1.

[0264] The elastomeric compositions described earlier, as well as the elastomeric compositions of the other components of the tyre 1, can be vulcanized according to known techniques, in particular using the sulfur-based vulcanization systems commonly used for elastomeric polymers. To this end, in the elastomeric compositions, after one or more thermomechanical treatment steps, a sulfur-based vulcanizing agent is incorporated together with a vulcanization accelerator. In the last step of the treatment, the temperature is kept substantially below 140°C, in order to avoid any unwanted pre-crosslinking phenomena.

[0265] The vulcanizing agents most advantageously used are sulfur or sulfur-containing molecules (sulfur donors) with accelerators and activators known to the person skilled in the art.

[0266] Particularly effective activators are: zinc-based compounds, in particular ZnO, ZnCO3, zinc salts of saturated or unsaturated fatty acids containing from 8 to 18 carbon atoms (for example, zinc stearate), which are preferably formed in situ in the elastomeric composition from ZnO and fatty acids; and also BiO, PbO, Pb3O4, PbO2or mixtures thereof.

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

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

[0269] For example, the following additives can be added to the elastomeric compositions: antioxidants, anti-aging agents, plasticizers, tackifiers, anti-ozonants, modified resins, fibers (aromatic polyamide or fibers of natural origin) or mixtures thereof.

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

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

[0272] Table 1

[0273]

[0274]

[0275] * phr of dry polymer without extender oil

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

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

[0278] CB: CRX TM 1391 (Cabot)

[0279] Silica: (Evonik)

[0280] Liquid copolymer (grip enhancer): low molecular weight butadiene / styrene liquid copolymer (4500 g / mol) - DYNACOL 4200 (Cray Valley) (Cray Valley)

[0281] Extender oil: TDAE (Orgkhim)

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

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

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

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

[0286] Stearic acid: Stearic acid (Undesa)

[0287] Zinc oxide: (Zincol Ossidi)

[0288] Silane: SILAN (Evonik)

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

[0290] Wax: WAX (Repsol)

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

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

[0293] Sulfur: 90P (Rhein Chemie)

[0294] Crosslinking agent: Bisfunctional 1,6-bis(NN'-dibenzylthiocarbamoyl disulfide)- hexane 9188 (Lanxess)

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

[0296] Vulcanization accelerator 2: Diphenylbenzothiazyl disulfide 80 (Rhein Chemie)

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

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

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

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

[0301] According to the present application, the ratio Rl between the dynamic modulus of elasticity E' of the second vulcanized elastomeric material of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 measured at 10 Hz frequency and 23°C and the dynamic modulus of elasticity E' of the first vulcanized elastomeric material of the central annular portion LI of the radially outer portion 11 and of the radially inner portion 12 of the tread band 8 measured at 10 Hz frequency and 23°C is comprised between 0.6 and 1.2, preferably comprised between 0.7 and 1.1.

[0302] Moreover, the ratio R2 between the tandelta of the second vulcanized elastomeric material of the lateral annular portions L2, L3 of the radially outer portion 11 of the tread band 8 measured at 10 Hz frequency and 70°C and the tandelta of the first vulcanized elastomeric material of the central annular portion LI of the radially outer portion 11 and of the radially inner portion 12 of the tread band 8 measured at 10 Hz frequency and 23°C is comprised between 0.6 and 1.2, preferably comprised between 0.7 and 1.1.

[0303] As mentioned above, the Applicant has observed through experiments that by controlling the value of the above-mentioned ratio Rl between the rigidity characteristics related to the value of the dynamic modulus of elasticity E' and the ratio R2 between the hysteresis characteristics related to the value of the tandelta close to 1, it can be advantageous to have an optimal dynamic hysteresis behavior both in the "hot" use conditions of the tire, while at the same time improving the driving behavior and the grip performance on the road in the "cold" use conditions.

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

[0305] The present application will now be illustrated by means of some examples, only for illustrative purposes and not limitative purposes.

[0306] Properties of the vulcanized elastomeric composition

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

[0308] The amounts of the various components in the elastomeric compositions are in phr, while the ingredients are as defined at the bottom of the preceding Table 1.

[0309] Table 2

[0310]

[0311]

[0312] phr of dry polymer without extender oil

[0313] The following Table 3 gives the results of the static and dynamic mechanical analyses carried out on composition samples of the aforementioned first vulcanized elastomeric material of the central annular portion LI and of the radially inner portion 12 of the radially outer portion 11 of the tread band 8 of the front tire 1 according to the application, as well as of the second vulcanized elastomeric material of the lateral annular portions L2, L3 of the radially outer portion 11, whose formulations have been indicated in the preceding Table 2.

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

[0315] Table 3

[0316]

[0317]

[0318] CA1: load at 100% elongation

[0319] CA3: load at 300% elongation

[0320] The following Table 4 gives the ratio R1 between the dynamic mechanical properties of the elastic modulus E’ and the ratio R2 between the tandelta, between the various vulcanized elastomeric materials indicated earlier and in each vulcanized elastomeric material, as far as they meet the purposes of the application.

[0321] Table 4

[0322]

[0323] It is clear from Table 4 that the values of the ratios R1 and R2 are close to 1, respectively, indicating that the second vulcanized elastomeric material and the first vulcanized elastomeric material respectively exhibit homogeneous behavior in both the “cold” and “hot” conditions of use.

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

[0325] Tire outdoor test

[0326] In order to seek to improve performance, the Applicant carried out comparative driving tests on a super sport tire for front wheels of size 120 / 70ZR17 with a transverse curvature ratio of about equal to 0.42.

[0327] The tire according to the present application has a "crown base" configuration of the tread band as described above with reference to Figure 2 The performance of this tire was compared with that of a comparative tire of similar size and structure but with a different configuration and composition of the tread band only.

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

[0329] The tread band of the comparative tire was made with the materials given in the following Table 5.

[0330] Table 5 - Comparative tire

[0331] Compound Single elastomeric material of the tread band S-SBR 1 98 S-SBR 2 40 CB 80 Extending oil 15 Resin 1 14 Resin 2 1.5 Stearic acid 1.5 Zinc oxide 5 Antiozonant 2 Sulfur 2.5 Vulcanization accelerator 2.5 Vulcanization retarder 0.2

[0332] * phr of dry polymer without extender oil

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

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

[0335] CB: CRX TM 1391 (Cabot)

[0336] Extender oil: TDAE (Nynas)

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

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

[0339] Stearic acid: Stearic acid (Wilmar)

[0340] Zinc oxide: (Zincol Ossidi)

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

[0342] Sulfur: 90P (Rhein Chemie)

[0343] Vulcanization accelerator: N-tert-butylbenzothiazylsulfenamide - TBBS 80 (Rhein Chemie)

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

[0345] Different test missions were carried out on a private circuit, by performing a series of maneuvers to test the adhesion and maneuverability in dry and wet conditions. The evaluation of the driver represents the average of the evaluations drawn in the various maneuvers.

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

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

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

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

[0350] The test was carried out using a BMW S1000 RR motorcycle of the "Super Sport" submarket.

[0351] The following tables 6 and 7 summarize the scores given by the test personnel in the tests carried out on dry ground and on wet ground, respectively, for the various performance types expected from the test tires.

[0352] In tables 6 and 7, the performance of the comparison tires is indicated with the symbol " / ", while for the performance of the tires according to the application, the symbol "=" is used to indicate an evaluation identical to that of the comparison tires, and the symbol "+" is used to indicate an improvement in performance with respect to the comparison tires, and the greater the number of symbols "+" the greater the improvement in performance.

[0353] Table 6 (tests on dry ground)

[0354]

[0355] Table 7 (tests on wet ground)

[0356] Tire Comparative front tire Front tire according to the invention Front grip / ++ Traction at braking / ++ Safety feeling / ++ Driving precision / ++ Driving / thrust / ++

[0357] It was also found during the tests performed that the use of the tyre according to the application made it possible to significantly reduce the lap time on the test track.

[0358] The results given in Tables 6 and 7 show that the tyre according to the application exhibits a greater improved behaviour in terms of both grip and manoeuvrability with respect to the comparative tyre, which is already very good on wet ground, and also a greater improvement in the camber angle, which is normally not achievable with front tyres on wet ground.

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

[0360] Various modifications can be made to the embodiments described in detail without departing from the scope of the application, which is defined by the following claims.

Claims

1. A motorcycle front tire (1), said motorcycle front tire comprising an equatorial plane (XX) and a tread band (8) having a full axial extension (L), in, The tread band (8) includes: a) Radial outer portion (11), said radial outer portion comprising: a1) A central annular portion (L1) arranged across the equatorial plane (XX) of the front tire (1) of the motorcycle and made of a first vulcanized elastomer material, and a2) A pair of lateral annular portions (L2, L3) arranged on opposite sides of the central annular portion (L1) relative to the equatorial plane (XX) of the front tire of the motorcycle (1), the lateral annular portions (L2, L3) being made of a second vulcanized elastomer material; b) Radial inner portion (12), which extends below the radial outer portion (11) of the tread belt (8) and along the entire axial extension of the tread belt, the radial inner portion (12) being made of the first vulcanized elastomer material; The ratio R1 between the dynamic elastic modulus E' of the second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) measured at 10 Hz and 23 °C and the dynamic elastic modulus E' of the first vulcanized elastomer material of the central annular portion (L1) and the radially inner portion (12) of the radially outer portion (11) of the tread band (8) measured at 10 Hz and 23 °C is between 0.6 and 1.2; and The ratio R2 between the loss factor of the second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) measured at 10 Hz and 70 °C and the loss factor of the first vulcanized elastomer material of the central annular portion (L1) and the radially inner portion (12) of the radially outer portion (11) of the tread band (8) measured at 10 Hz and 23 °C is between 0.6 and 1.

2.

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

3. The motorcycle front tire (1) according to claim 1 or 2, wherein, The first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread belt (8) has a loss factor between 0.37 and 0.47, measured at 10 Hz and 23 °C.

4. The motorcycle front tire (1) according to claim 1 or 2, wherein, The second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread strip (8) has a dynamic elastic modulus E' between 5.2 MPa and 6.5 MPa, measured at 10 Hz and 23 °C.

5. The motorcycle front tire (1) according to claim 1 or 2, wherein, The second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread belt (8) has a loss factor between 0.34 and 0.44, measured at 10 Hz and 70°C.

6. The motorcycle front tire (1) according to claim 1 or 2, wherein, The first vulcanized elastomer material of the central annular portion (L1) and the radial inner portion (12) of the radial outer portion (11) of the tread strip (8) is obtained by vulcanizing an elastomer material comprising at least one elastomeric diene polymer of 100 phr and white reinforcing filler of 70 to 110 phr.

7. The motorcycle front tire (1) according to claim 1 or 2, wherein, The second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread strip (8) is obtained by vulcanizing an elastomer material comprising at least one elastomer diene polymer of 100 phr and carbon black reinforcing filler of 40 to 100 phr.

8. The motorcycle front tire (1) according to claim 1 or 2, wherein, The central annular portion (L1) of the radially outer portion (11) of the tread band (8) extends laterally at 5%-25% of the semi-axial extension (L / 2) of the tread band (8).

9. The motorcycle front tire (1) according to claim 1 or 2, wherein, The ends (17, 18) of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) located near the equatorial plane (XX) are arranged at a distance from the equatorial plane (XX), the distance being at least 10% of the semi-axial extension (L / 2) of the tread band (8).

10. The motorcycle front tire (1) according to claim 1 or 2, wherein, Each of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is arranged axially outside the central annular portion (L1) and adjacent to the central annular portion to define an interface (16) that separates the central annular portion (L1) from the lateral annular portions (L2, L3) in the axial direction.

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

12. The motorcycle front tire (1) according to claim 1 or 2, wherein, The central annular portion (L1) of the radially outer portion (11) of the tread band (8) is substantially without grooves.

13. The motorcycle front tire (1) according to claim 1 or 2, wherein, The radially outer portion (11) of the tread band (8) and its lateral annular portions (L2, L3) each include a first lateral annular sub-portion (L2', L3') located near the equatorial plane (XX) and a second lateral annular sub-portion (L2', L3') located far from the equatorial plane (XX). Furthermore, the motorcycle front tire (1) includes a plurality of grooves (13, 14) formed in the first lateral annular sub-parts (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread belt (8).

14. The motorcycle front tire (1) according to claim 13, wherein, The first lateral annular sub-part (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) extends laterally along 40%-65% of the semi-axial extension (L / 2) of the tread band (8).

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

16. The motorcycle front tire (1) according to claim 13, wherein, The void rubber ratio defined in each first lateral annular sub-part (L2', L3') of the radially outer portion (11) of the tread belt (8) of the plurality of grooves (13, 14) is greater than or equal to 0% and less than or equal to 30%.

17. The motorcycle front tire (1) according to claim 16, wherein, Each of the lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) is arranged axially outside the central annular portion (L1) and adjacent to the central annular portion to define an interface (16) separating the central annular portion (L1) from the lateral annular portions (L2, L3) in an axial direction; and wherein the void rubber ratio defined in the first annular segment (A) of each first lateral annular sub-portion (L2', L3') of the radially outer portion (11) of the lateral annular portion (L2, L3) of the tread band (8) increases from the interface (16) along the semi-axial extension (L / 2) of the tread band (8) away from the equatorial plane (XX) of the motorcycle front tire (1), the first annular segment being arranged axially outside the central annular portion (L1) and adjacent to the central annular portion.

18. The motorcycle front tire (1) according to claim 17, wherein, The first annular segment (A) extends laterally from the end (17, 18) of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) located near the equatorial plane (XX) along the semi-axial extension (L / 2) of the tread band (8) at a distance of 5%-25%.

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

20. The motorcycle front tire (1) according to claim 19, wherein, The outer axial end (A') of the first annular segment (A) is located at a distance of at least 13% of the semi-axial extension (L / 2) of the tread strip (8) from the equatorial plane (XX) of the front tire of the motorcycle (1).

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

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

23. The motorcycle front tire (1) according to claim 21, wherein, In the second annular segment (B), the void rubber ratio decreases from a maximum of about 25% at the axially outer end (A') of the first annular segment (A) to a minimum of about 0% at the axially outer end of the first lateral annular sub-part (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread belt (8).

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

25. The motorcycle front tire (1) according to claim 13, wherein, The second lateral annular sub-part (L2”, L3”) of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) extends laterally along the semi-axial extension (L / 2) of the tread band (8) by 10%-55%.

26. The motorcycle front tire (1) according to claim 13, wherein, Each second lateral annular sub-part (L2”, L3”) of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) is substantially without grooves.

27. The motorcycle front tire (1) according to claim 1 or 2, wherein, The lateral curvature ratio of the front tire of the motorcycle is equal to or greater than 0.35 and equal to or less than 0.

50.

28. The motorcycle front tire (1) according to claim 1, wherein, The ratio R1 is between 0.7 and 1.

1.

29. The motorcycle front tire (1) according to claim 1, wherein, The ratio R2 is between 0.7 and 1.

1.

30. The motorcycle front tire (1) according to claim 2, wherein, The first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread strip (8) has a dynamic elastic modulus E' between 6.0 MPa and 6.4 MPa, measured at 10 Hz and 23 °C.

31. The motorcycle front tire (1) according to claim 3, wherein, The first vulcanized elastomer material of the central annular portion (L1) of the radially outer portion (11) and the radially inner portion (12) of the tread belt (8) has a loss factor between 0.41 and 0.45, measured at 10 Hz and 23 °C.

32. The motorcycle front tire (1) according to claim 4, wherein, The second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread strip (8) has a dynamic elastic modulus E' between 5.6 MPa and 6.0 MPa, measured at 10 Hz and 23 °C.

33. The motorcycle front tire (1) according to claim 5, wherein, The second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread belt (8) has a loss factor between 0.38 and 0.40, measured at 10 Hz and 70°C.

34. The motorcycle front tire (1) according to claim 6, wherein, The white reinforcing filler includes an inorganic material, the amount of which, by weight, is equal to or greater than 80% of the total weight of the white reinforcing filler, and the inorganic material is selected from silica, alumina, silicates, alumina, calcium carbonate, kaolin, titanium dioxide, and mixtures thereof.

35. The motorcycle front tire (1) according to claim 34, wherein, The amount of inorganic material included in the white reinforcing filler is equal to or greater than 85% by weight of the total weight of the white reinforcing filler.

36. The motorcycle front tire (1) according to claim 35, wherein, The amount of inorganic material included in the white reinforcing filler is equal to or greater than 90% by weight of the total weight of the white reinforcing filler.

37. The motorcycle front tire (1) according to claim 36, wherein, The amount of inorganic material included in the white reinforcing filler is equal to or greater than 95% by weight of the total weight of the white reinforcing filler.

38. The motorcycle front tire (1) according to claim 7, wherein, The second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread strip (8) is obtained by vulcanizing an elastomer material comprising at least one elastomer diene polymer of 100 phr and carbon black reinforcing filler of 50 to 90 phr.

39. The motorcycle front tire (1) according to claim 38, wherein, The second vulcanized elastomer material of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread strip (8) is obtained by vulcanizing an elastomer material comprising at least one elastomer diene polymer of 100 phr and carbon black reinforcing filler of 60 to 80 phr.

40. The motorcycle front tire (1) according to claim 8, wherein, The central annular portion (L1) of the radially outer portion (11) of the tread band (8) extends laterally at 10%-20% of the semi-axial extension (L / 2) of the tread band (8).

41. The motorcycle front tire (1) according to claim 11, wherein, The lateral annular portions (L2, L3) of the radially outer portion (11) of the tread band (8) extend laterally along 80%-90% of the semi-axial extension (L / 2) of the tread band (8).

42. The motorcycle front tire (1) according to claim 14, wherein, The first lateral annular sub-part (L2', L3') of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) extends laterally along 45%-60% of the semi-axial extension (L / 2) of the tread band (8).

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

44. The motorcycle front tire (1) according to claim 16, wherein, The void rubber ratio defined in each first lateral annular sub-part (L2', L3') of the radially outer portion (11) of the tread belt (8) of the plurality of grooves (13, 14) is greater than or equal to 0% and less than or equal to 25%.

45. The motorcycle front tire (1) according to claim 18, wherein, The first annular segment (A) extends laterally from the end (17, 18) of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) near the equatorial plane (XX) along the semi-axial extension (L / 2) of the tread band (8) at 10%-20%.

46. ​​The motorcycle front tire (1) according to claim 20, wherein, The outer axial end (A') of the first annular segment (A) is located at a distance between 15% and 35% of the semi-axial extension (L / 2) of the tread strip (8) from the equatorial plane (XX) of the front tire of the motorcycle (1).

47. The motorcycle front tire (1) according to claim 22, wherein, The second annular segment (B) extends laterally from the first annular segment (A) along 25%-50% of the semi-axial extension (L / 2) of the tread strip (8).

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

49. The motorcycle front tire (1) according to claim 25, wherein, The second lateral annular sub-part (L2”, L3”) of the lateral annular portion (L2, L3) of the radially outer portion (11) of the tread band (8) extends laterally at 20%-45% of the semi-axial extension (L / 2) of the tread band (8).

50. The motorcycle front tire (1) according to claim 27, wherein, The lateral curvature ratio of the front tire of the motorcycle is equal to or greater than 0.39 and equal to or less than 0.

45.

51. The motorcycle front tire (1) according to claim 50, wherein, The lateral curvature ratio of the front tire of the motorcycle is equal to or greater than 0.40 and equal to or less than 0.44.

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