Motorcycle tyre

Abstract

The present application relates to a motorcycle tyre comprising a tread band (8) having a plurality of main grooves (20; 60) arranged on opposite sides with respect to the equatorial plane (X-X) of the motorcycle tyre and a void rubber ratio greater than 10%. Each of said main grooves (20; 60) comprises a first straight portion (21; 61) inclined by a first angle (a) less than 45° with respect to the equatorial plane (X-X) and having an end (21a; 61a) close to said equatorial plane (X-X) and an end (21b; 61b) far from said equatorial plane (X-X). Each of said main grooves (20; 60) further comprises a second straight portion (22; 62) inclined by a second angle (b) comprised between 90° and 160° with respect to said first straight portion (21; 61) and having an end (22a; 62a) close to the equatorial plane (X-X) and an end (22b; 62b) far from the equatorial plane (X-X). Said second straight portion (22; 62) is shorter than said first straight portion (21; 61).

Description

Technical Field

[0001] This invention relates to a motorcycle tire. Background Technology

[0002] The tires of this invention are intended for mounting on the front and rear wheels of "large endurance" (or "large adventure" or "dual-purpose") motorcycles, which are known to be large-displacement, high-power, and heavy motorcycles designed for both asphalt and off-road driving. Such motorcycles typically have a piston displacement equal to or greater than 1000 cm³, a power output equal to or greater than 100 hp, a maximum torque equal to or greater than 100 Nm, and a mass equal to or greater than 180 kg.

[0003] Some examples of "large endurance" motorcycles include the BMW GS 1300, KTM 1290 Super AdventureR, and Honda CRF1100L Africa Twin.

[0004] "Large endurance" motorcycles have a very wide range of uses, ranging from pure road use (comparable to sport touring while also having the characteristics of a super sport bike) to off-road use that is even more demanding than simply paved roads, such as riding on all-terrain tracks (the so-called "mud track racetrack") or on paths that include riverbeds, soft ground, mud, sand, and various types and levels of rugged terrain.

[0005] To meet all these types of uses, different types of "large endurance" tires are available on the market, each focused on a clearly defined type of use, such as: road sport driving, road touring driving, road touring combined with unpaved dirt roads, road driving combined with light off-roading, and heavy off-roading combined with road driving, etc.

[0006] Typically, large endurance motorcycle tires, primarily designed for use on both highways and dirt roads, are approved for a maximum speed of at least 210 km / h (ETRTO speed index: H). These tires typically have a maximum radial section width between 90 mm and 170 mm (e.g., between 90 mm and 120 mm for front tires and between 130 mm and 170 mm for rear tires), and are mounted on rims with mounting diameters typically between approximately 17 inches and 21 inches (e.g., between 19 inches and 21 inches for front tires and between 17 inches and 18 inches for rear tires).

[0007] The tire of this invention is intended to equip “large endurance” motorcycles approved for use on a combination of highway tolling and dirt roads. Therefore, the tire is primarily used on highways in various configurations (including rider only; rider and luggage; rider and passenger; or rider, passenger and luggage) and in various climatic conditions (dry or wet highway surfaces), and occasionally on dirt roads.

[0008] "Large endurance" type motorcycle tires typically include a tread band, the tread pattern of which is defined by multiple grooves of different shapes and orientations. Examples of this type of tire have been described in patent documents EP2760682B1 and EP2307207B1 belonging to the same applicant. Summary of the Invention

[0009] Throughout the specification and the appended claims, unless otherwise stated, when referring to certain values ​​of certain angles, they are treated as absolute values, that is, both positive and negative values ​​relative to a certain reference plane or direction.

[0010] Furthermore, when referring to any range of values ​​between the minimum and maximum values, the minimum and maximum values ​​are considered to be included in that range unless otherwise explicitly stated otherwise.

[0011] Furthermore, even if not explicitly described, all ranges include any combination of the stated minimum and maximum values, and include any intermediate ranges.

[0012] Unless otherwise specified, any numerical value is to be regarded as being preceded by the term "about" to indicate any value that is slightly different from the stated value, for example, taking into account dimensional tolerances common in the field of reference.

[0013] The following definitions apply in the following text.

[0014] The term "motorcycle tire" is used to refer to tires with a high curvature ratio (typically greater than 0.20) and the ability to achieve a high camber when cornering.

[0015] The term "curvature ratio" is used to represent the ratio between the distance between the radially highest point of the tire tread strip and the tire's maximum chord length (also indicated by an "arrow") in the tire's cross-section and the tire's own maximum chord length.

[0016] The terms "maximum chord length" or "maximum width of radial section" are used to indicate the maximum width of the tire profile, that is, the length of the segment with the two outermost points of the tread strip as its endpoints.

[0017] The term "tire footprint area" refers to the portion of the tire that comes into contact with the ground or road surface when the tire is mounted on a rim and a predetermined vertical load is applied to the tire.

[0018] The term "equatorial plane" for a tire is used to refer to the plane perpendicular to the tire's axis of rotation and that divides the tire into two symmetrical and equal parts.

[0019] The term "tread pattern" is used to describe the representation of all points of the tread band (including grooves) on a plane perpendicular to the tire's equatorial plane and tangent to the tire's maximum diameter. This representation corresponds to the planar extension of the outermost contour of the tread band.

[0020] Measurements of linear quantities (distance, width, length, axial extension and / or circumferential extension, etc.) and / or angles should be understood to involve the tread pattern as defined above.

[0021] The term “circumferential extension” of a tire, tread belt or a portion or segment thereof is used to refer to the planar extension of the outermost radial surface of a tire, tread belt or a portion or segment thereof in a plane tangent to the tire.

[0022] The term "void-to-rubber ratio" is used to describe the ratio between the total surface area of ​​the grooves of a specific annular portion of the tire tread belt or a specific portion of the tire tread pattern (which may be the entire tread belt or the entire tread pattern) and the surface area of ​​that specific annular portion of the tread belt or the specific portion of the tread pattern (which may be the entire tread belt or the entire tread pattern).

[0023] The term "annular portion" of the tread belt is used to refer to the portion of the tread belt that extends circumferentially along the entire tread belt and has a predetermined axial extension, which is measured in a plane orthogonal to the equatorial plane.

[0024] The terms “radial” and “axial”, as well as the expressions “radial inside / outer” and “axial inside / outer”, are used with reference to directions substantially parallel to the tire’s equatorial plane and substantially perpendicular to the tire’s equatorial plane, respectively; that is, with reference to directions substantially perpendicular to the tire’s axis of rotation and substantially parallel to the tire’s axis of rotation, respectively.

[0025] The terms “circumferential” and “circumferentially” are used with reference to the circumferential extension direction of the tire (i.e., the direction in which the tire rolls), which corresponds to a direction located on a plane that coincides with or is substantially parallel to the equatorial plane of the tire.

[0026] The expression "basically parallel" refers not only to a state of complete parallelism, but also to a state where the angle of deviation from complete parallelism is no greater than 10°.

[0027] The terms "axial innermost" and "axial outermost" refer to positions closer to and further away from the equatorial plane relative to the reference element, respectively. Therefore, for example, when the axial distance between the first groove portion and the equatorial plane is less than the axial distance between the second groove portion and the equatorial plane, the first groove portion is located axially innermost relative to the second groove portion. Similarly, when the axial distance between the first groove portion and the equatorial plane is greater than the axial distance between the second groove portion and the equatorial plane, the first groove portion is located axially outermost relative to the second groove portion.

[0028] The term "position closer to the equatorial plane" is used to indicate a position that is closer to the equatorial plane than "position further away from the equatorial plane".

[0029] The term “width” for a trench or a portion or segment thereof is used to refer to the dimension of the trench or a portion or segment thereof measured along a direction orthogonal to the trajectory in which the trench or a portion or segment thereof extends.

[0030] The term “length” for a trench or a portion or segment thereof is used to refer to the length of the trench or a portion or segment thereof measured along the trajectory along which the trench or a portion or segment thereof extends.

[0031] The term “axial extension” for a trench or a portion or segment thereof is used to indicate the projected length of the trench or a portion or segment thereof on a plane orthogonal to the equatorial plane.

[0032] The term “circumferential extension” for a trench or a portion or segment thereof is used to indicate the projected length of the trench or a portion or segment thereof on a plane parallel to the equatorial plane.

[0033] In the following text, when the circumferential center points of two grooves or their corresponding portions or segments are not located on the same plane perpendicular to the tire equator, the groove or its portion or segment is considered to be "circumferentially offset" relative to the other groove or its portion or segment.

[0034] When the projections of two trenches or their respective portions or segments onto the equatorial plane at least partially overlap, one trench or its portion or segment is instead considered to overlap with the other trench or its portion or segment in the axial direction. In this case, the projection of at least a segment of each of the two trenches onto the equatorial plane is the same as the projection of at least a segment of the other trench onto the equatorial plane.

[0035] Regarding the angle of the grooves, groove portions, or segments on the tread relative to the tire's equatorial plane, for each point on the groove, groove portion, or segment, this angle should be understood as an angle (in absolute value) formed by performing a rotation, starting from the direction defined by the equatorial plane in the tread pattern and extending to a direction tangent to the groove or groove portion passing through said point. In the case where the tire is intended to be mounted on the rear wheel of a motorcycle, the aforementioned rotation should be understood as a rotation performed by a vector oriented in the opposite direction to the tire's rotation, while in the case where the tire is intended to be mounted on the front wheel of a motorcycle, the aforementioned rotation should be understood as a rotation performed by a vector oriented in the tire's rotation direction.

[0036] Regarding the angle of a groove portion or segment relative to a portion or segment of the same groove (hereinafter referred to as the reference portion or segment), for each point on the groove portion or segment, the angle should be understood as the angle formed when rotating from the direction defined by the reference portion or segment in the tread pattern to a direction tangent to the groove portion or segment passing through that point (taking an absolute value, and the angle is between 0° and 180°).

[0037] As previously mentioned, the applicant has considered the motorcycle segment with a very wide range of applications for "large endurance" motorcycles.

[0038] The applicant has observed that, in order to best cover the entire application range of “large endurance” motorcycles, they should be equipped with tires that are suitable for allowing high performance in both on-road (primarily traction, braking, stability at high speeds, grip on dry and wet surfaces, and handling) and off-road (primarily traction, controllability, and directionality), while also having the ability to travel several kilometers.

[0039] However, the applicant has found that, given the increasingly common trend of achieving both ultimate on-road performance and ultimate off-road performance, the aforementioned performance characteristics are at least partially contradictory.

[0040] The applicant has indeed noted that tires that are allowed to perform well on paved roads often have performance limitations in demanding off-road conditions, and vice versa.

[0041] The applicant has also noted that a good compromise solution that balances on-road and off-road use does not allow for optimal performance in either area (on-road and off-road).

[0042] The applicant has observed that, based on customer demand, the market has recently shifted towards more specialized solutions, offering more segmented tires for "large endurance" motorcycles, each focused on a specific application for the motorcycle. Consistently, the applicant has launched "large endurance" motorcycle tires for primary on-road use and "large endurance" motorcycle tires for primary off-road use.

[0043] Tires designed for primary highway use are designed to maximize performance in the following areas: stability and controllability at high speeds (during straight driving and cornering), handling (or driving ease), mileage, traction and braking, comfort, and wear regularity when driving on asphalt surfaces. Furthermore, given that these tires are often used year-round and in various weather conditions, they must be able to achieve the above performance on both dry and low-grip highway surfaces (such as, in particular, wet surfaces).

[0044] Tires designed for primary off-road use (even demanding off-road applications) are instead designed to maximize control and directionality on rough, slippery, and / or uneven terrain (such as sand, mud, and gravel). These tires must also be able to achieve the same performance on wet terrain.

[0045] The applicant has focused its attention on the segment of “large endurance” motorcycle tires for primary highway use, particularly for road trips combined with dirt roads, hereinafter referred to as “large endurance highway tires” for simplicity.

[0046] The applicant has argued that these tires were chosen by users seeking performance on paved roads and also anticipating off-road use (albeit not extreme / harsh).

[0047] The applicant has first observed that, in order to ensure the desired off-road performance, it is recommended that the tread belt have a clearance rubber ratio of not less than 10%, which is greater than the clearance rubber ratio typically provided in road tires designed for on-road use only (such as tires belonging to the "super sport" category).

[0048] The applicant has considered how to improve the performance of large endurance road tires compared to tires in the same segment of the market (hereinafter referred to as "reference tires") on dry or wet surfaces, in terms of traction (in the case of rear tires) and braking (in the case of front and rear tires), without compromising off-road performance, i.e., maintaining off-road performance at least equivalent to that provided by the reference tires.

[0049] The applicant has observed that, regardless of the tire's market segment, its performance on both dry and wet surfaces improves with its ability to adhere to the road surface during acceleration and braking; therefore, the lower the tire's void-to-rubber ratio, the greater this ability. Specifically, the applicant has observed that, during straight-line driving and cornering, fewer and / or smaller grooves in the tire track area result in greater tire adhesion to the road surface.

[0050] Therefore, according to the applicant, one way to improve the traction and braking performance of large endurance road tires is to reduce the number and / or size of the gaps defined by the grooves in the tire track area, while still retaining enough gaps to allow water to drain from the tire track area in the case of wet road surfaces.

[0051] However, the applicant has observed that reducing the number of gaps in the tire track area leads to a deterioration in the tire's off-road performance, resulting in a situation contrary to the desire for off-road performance to be at least equal to that of the reference tire.

[0052] Regarding off-road performance, the applicant has observed that in large endurance road tires, this performance is typically achieved by creating long grooves in the tread area that are slightly angled relative to the equator. In fact, these grooves allow for effective counterbalancing of the lateral forces experienced by the tread band during slippage in off-road driving and when driving on wet terrain, thereby ensuring the necessary and desired controllability and directionality.

[0053] Therefore, the applicant believes that, in order to ensure that the off-road performance of the large endurance road tire does not deteriorate relative to the off-road performance of the reference tire, it is recommended to continue to provide long grooves that are slightly inclined relative to the equatorial plane in the tire track area.

[0054] However, the applicant has observed that such trenches typically include: a portion oriented to particularly counteract the aforementioned lateral forces (hereinafter referred to as the "first portion"); and other portions oriented to provide no counteracting effect on the aforementioned lateral forces (hereinafter referred to as the "second portion").

[0055] The applicant has also observed that, due to their orientation, the second part is prone to premature wear when the tires are used on off-road tracks or asphalt surfaces (whether the surface is dry or wet), during slippage, and during acceleration and braking, as the edges of the second part slip relative to the ground.

[0056] Therefore, in order to achieve the goal of not deteriorating performance relative to the reference tire on off-road tracks, while reducing the number and / or size of gaps in the tire groove area to improve road grip and thus improve traction and braking performance on highways, the applicant has considered reducing the size of the aforementioned second part while maintaining the aforementioned first part sufficiently extended. According to the applicant, by doing so, it is also possible to obtain a favorable reduction in overall wear that also occurs at the edges of the aforementioned grooves.

[0057] Therefore, the present invention relates to a tire including a tread strip.

[0058] Preferably, the tread band includes multiple main grooves.

[0059] Preferably, the tread belt has a void rubber ratio greater than 10%.

[0060] Preferably, the main grooves are arranged on opposite sides of the tire's equatorial plane.

[0061] Preferably, each of the main trenches includes a first straight section.

[0062] Preferably, the first straight section is inclined at a first angle relative to the equatorial plane.

[0063] Preferably, the first angle is less than 45°.

[0064] Preferably, the first straight portion has a first end near the equatorial plane.

[0065] Preferably, the first straight portion has a second end that is away from the equatorial plane.

[0066] Preferably, each of the main trenches includes a second straight section.

[0067] Preferably, the second straight portion is inclined at a second angle relative to the first straight portion.

[0068] Preferably, the second angle is greater than 90°.

[0069] Preferably, the second angle is less than 160°.

[0070] In a preferred embodiment, the second angle is between 90° and 160°.

[0071] Preferably, the second straight portion has a third end near the equatorial plane.

[0072] Preferably, the second straight portion has a fourth end that is away from the equatorial plane.

[0073] Preferably, the second straight section is shorter than the first straight section.

[0074] The applicant has discovered that a large endurance road tire has a tread belt with the aforementioned void-to-rubber ratio and includes the grooves described above, which allows for the combination of off-road performance desired by the customer with improved acceleration and braking performance on dry and wet roads.

[0075] The increased tire grip due to the reduced size of the second straight section results in improved road performance.

[0076] The desired off-road performance is achieved by providing a void-to-rubber ratio of more than 10% and by the length and inclination of the first straight section of the aforementioned groove.

[0077] The shortened length and specific inclination of the second straight section allow for reduced edge wear of the aforementioned grooves.

[0078] The present invention may have at least one of the preferred features described below.

[0079] Preferably, the porosity of the rubber is greater than 10.5%, more preferably greater than 11%, and even more preferably greater than 12%.

[0080] Preferably, the porosity ratio is less than 22%, more preferably less than 21%, and even more preferably less than 20%.

[0081] In a preferred embodiment, the void rubber ratio is between 10.5% and 22%, preferably between 11% and 21%, and even more preferably between 12% and 20%. For example, in a rear tire with a specification of 170 / 60 / R17, the void rubber ratio is equal to 14.5%, and in a front tire with a specification of 120 / 70 / R19, the void rubber ratio is equal to 16.5%.

[0082] The applicant believes that setting the aforementioned gap rubber ratio value makes it possible to achieve the desired on-road performance while maintaining the same off-road performance.

[0083] The front tire has a higher clearance-to-rubber ratio than the rear tire. This is because it's necessary to maximize the countermeasures against lateral forces experienced by the front tire during rear tire slippage, and also because the front tire is typically smaller and has a smaller radius of curvature than the rear tire, resulting in a narrower and longer tire track area for the front tire. This means that under certain driving conditions, no lateral grooves from the tire may be within the tire track area, necessitating a greater number of grooves within the track area to achieve the desired off-road and wet performance.

[0084] However, the applicant argues that such a large value for the puddle-to-rubber ratio of the front tires does not affect the road performance of these tires because at high speeds (such as those expected by users in this motorcycle segment), the front tires tend to lift off the road surface, resulting in a smaller tire mark area and consequently a smaller number of punctures in the tire mark area.

[0085] Preferably, the first angle is less than 40°, more preferably less than 35°, and even more preferably less than 30°.

[0086] Preferably, the second angle is greater than 95°, more preferably greater than 100°.

[0087] Preferably, the second angle is less than 150°, more preferably less than 145°, and even more preferably less than 140°.

[0088] In a preferred embodiment, the second angle is between 95° and 150°, preferably between 100° and 145°, and more preferably between 100° and 140°.

[0089] The applicant believes that the aforementioned angle setting may improve both the on-road and off-road performance of the tire, while suppressing edge wear of the aforementioned grooves.

[0090] Preferably, the length of the second straight section is less than half the length of the first straight section, and more preferably less than one-third the length of the first straight section.

[0091] The applicant argues that this setup also allows for maximizing both the tire's on-road and off-road performance.

[0092] Preferably, the width of the first straight section gradually increases from the first end to the second end.

[0093] This ensures effective water expulsion from the tire track area when driving on wet surfaces. Furthermore, because the grooves tend to close in their narrower sections after high-speed acceleration and braking (such as those typically performed by users of large endurance road tires), the void-to-rubber ratio in the tire track area is reduced, thus increasing tire grip on the road surface and further enhancing tire performance on dry surfaces. The applicant argues that this fact does not negatively impact the ability to expel water from the tire track area when driving on wet roads. In this case, the load on the tire during acceleration and braking is actually lower than the load on the tire when driving on dry roads, and it would not cause the aforementioned narrower sections to close in any way.

[0094] Preferably, the first end is arranged at a distance from the equatorial plane that is less than 12% of the maximum radial width of the tread strip, more preferably less than 10% of the maximum radial width. This arrangement helps to effectively expel water from the tire track area when the tire is traveling on a wet road surface.

[0095] Preferably, the corresponding distance is greater than 3% of the maximum width of the radial section of the tread belt, and more preferably greater than 5% of the maximum width of the radial section.

[0096] In a preferred embodiment, the first end is arranged at a distance from the equatorial plane that is between 3% and 12% of the maximum width of the radial section of the tread, more preferably between 5% and 10% of the maximum width of the radial section.

[0097] Preferably, the third end is arranged at a distance from the equatorial plane that is less than 12% of the maximum width of the radial section of the tread, more preferably less than 10% of the maximum width of the radial section.

[0098] Preferably, the corresponding distance is greater than 3% of the maximum width of the radial section of the tread belt, and more preferably greater than 5% of the maximum width of the radial section.

[0099] In a preferred embodiment, the third end is arranged at a distance from the equatorial plane that is between 3% and 12% of the maximum width of the radial section of the tread, more preferably between 5% and 10% of the maximum width of the radial section.

[0100] Therefore, the tire has an annular portion of the tread band at the equatorial plane, and the void ratio of the annular portion is sufficiently reduced to improve grip on road surfaces and thus improve performance on both dry and wet road surfaces.

[0101] In some embodiments, the distance of the first end from the equatorial plane is equal to the distance of the third end from the equatorial plane.

[0102] Preferably, the second end is arranged at a distance from the equatorial plane that is less than 30% of the maximum width of the radial section of the tread belt, and more preferably less than 25% of the maximum width of the radial section of the tread belt.

[0103] Preferably, the distance is greater than 10% of the maximum radial cross-sectional width of the tread belt, and more preferably greater than 15% of the maximum radial cross-sectional width of the tread belt.

[0104] In a preferred embodiment, the second end is arranged at a distance from the equatorial plane that is between 10% and 30% of the maximum width of the radial section of the tread belt, more preferably between 15% and 25% of the maximum width of the radial section of the tread belt.

[0105] This setup helps achieve the desired off-road performance of the tires and ensures that even when the tires are turning slightly, the first straight portion of the main grooves remains within the tire track area, thus helping to ensure that water is drained from the tire track area even under driving conditions on wet road surfaces.

[0106] Preferably, the fourth end is arranged at a distance from the equatorial plane that is less than 30% of the maximum radial cross-sectional width of the tread belt, more preferably less than 25% of the maximum radial cross-sectional width of the tread belt.

[0107] Preferably, the distance is greater than 10% of the maximum radial cross-sectional width of the tread belt, and more preferably greater than 15% of the maximum radial cross-sectional width of the tread belt.

[0108] In a preferred embodiment, the fourth end is arranged at a distance from the equatorial plane that is between 10% and 30% of the maximum width of the radial section of the tread belt, more preferably between 15% and 25% of the maximum width of the radial section of the tread belt.

[0109] This setting helps achieve the tire's desired off-road behavior and ensures that the second straight section of the main groove is also within the tire track area when the tire is making a slight turn.

[0110] Preferably, the first straight sections of all the main trenches are parallel to each other.

[0111] Preferably, the first straight portion of all main trenches has the same length.

[0112] Preferably, the second straight sections of all the main trenches are parallel to each other.

[0113] Preferably, the second straight portion of all main trenches has the same length.

[0114] Preferably, the plurality of main trenches include a first series of circumferentially successive main trenches arranged on one side relative to the equatorial plane.

[0115] Preferably, all the main trenches in the first series are identical to each other.

[0116] Preferably, the plurality of main trenches include a second series of circumferentially successive main trenches arranged on the other side of the equatorial plane.

[0117] Preferably, all the main trenches in the second series are identical to each other.

[0118] Preferably, the shape of the main groove in the second series of main grooves is mirror-reflected with the shape of the main groove in the first series of main grooves.

[0119] Preferably, the second series of main grooves is circumferentially offset relative to the first series of main grooves.

[0120] Preferably, in the case of the rear tire, each main groove in the second series of main grooves partially overlaps the corresponding main groove in the first series of main grooves along the axial direction at the corresponding groove location, wherein the circumferential extension of the corresponding groove location is less than 22% of the circumferential extension of each main groove, more preferably less than 20% of the circumferential extension of each main groove, and even more preferably less than 17% of the circumferential extension of each main groove.

[0121] The applicant has discovered that the partial overlap in the axial direction, as described above, allows the rear tire to achieve favorable regularity in terms of stiffness / deformation, noise, vibration, and wear during rolling. This is because the axial portion of the tread belt that does not contain the main grooves is not inserted into the axial portion of the tread belt that contains the main grooves, and because the axial portion of the tread belt that contains two opposing main grooves (which thus undergoes greater deformation than the axial portion containing only one main groove) has a reduced circumferential extension.

[0122] Preferably, in the case of the front tire, each main groove of the second series of main grooves partially overlaps the corresponding main groove of the first series of main grooves in the axial direction at the corresponding groove location, wherein the circumferential extension of the corresponding groove location is less than or equal to 55% of the circumferential extension of each main groove.

[0123] Preferably, the circumferential extension is greater than 20% of the circumferential extension of each main groove, and more preferably greater than 30% of the circumferential extension of each main groove.

[0124] In a preferred embodiment of the front tire, the circumferential extension is between 20% and 55% of the circumferential extension of each main groove, and preferably between 30% and 55% of the circumferential extension of each main groove.

[0125] The applicant has discovered that, even in the front tire, the partial overlap in the axial direction, as described above, allows for the aforementioned performance characteristics of the rear tire, regardless of whether the partial overlap in the axial direction of the main grooves in the front tire is greater than that in the rear tire. The applicant has also discovered that, because the front tire is smaller than the rear tire, it is generally stiffer and bears a lower vertical load than the rear tire, resulting in a reduced risk of excessive deformation.

[0126] Preferably, in all preferred embodiments of the tire of the present invention, the tread belt includes a plurality of secondary grooves.

[0127] Preferably, the circumferential extension of the secondary groove is shorter than that of the primary groove, so as not to increase the void rubber ratio in the tire track area.

[0128] Preferably, the circumferential extension of each secondary trench is less than 50% of the circumferential extension of the main trench, and more preferably less than 40% of the circumferential extension of the main trench.

[0129] More preferably, in the case of the rear tire, the circumferential extension of each secondary groove is less than 30% of the circumferential extension of each main groove.

[0130] Preferably, each secondary groove is arranged between two circumferentially successive primary grooves. In this way, an axial portion that extends sufficiently in the circumferential direction without grooves is avoided in the tire track area, between the two primary grooves, thus avoiding undesirable irregularities in terms of stiffness / deformation and wear, as well as noise and vibration.

[0131] Preferably, each secondary groove includes a first segment extending toward the equatorial plane. This first segment allows water to drain from the central area of ​​the tire track when the tire is traveling on a wet surface.

[0132] Preferably, each secondary groove includes a second segment extending from the corresponding first segment toward the end edge of the tread band. This second segment cooperates with the aforementioned first segment and the first straight portion of the main groove to drain water from the tire groove area.

[0133] Preferably, the second segment does not reach the end edge of the tread belt, so that the overall tread belt void ratio is maintained at a value suitable for ensuring the desired road performance.

[0134] Preferably, the first segment is tilted relative to the equatorial plane at a third angle, the third angle being greater than 90°, more preferably greater than 100°, even more preferably greater than 110°, and even more preferably greater than 120°.

[0135] Preferably, the third angle is less than 180°, more preferably less than 170°, even more preferably less than 160°, and even more preferably less than 140°.

[0136] In a preferred embodiment, the third angle is between 90° and 180°, more preferably between 100° and 170°, even more preferably between 110° and 160°, and even more preferably between 120° and 140°.

[0137] Preferably, the second segment is tilted relative to the first segment at a fourth angle, the fourth angle being less than 180°, more preferably less than 140°, even more preferably less than 130°, and even more preferably less than 120°.

[0138] Preferably, the fourth angle is greater than 40°, more preferably greater than 50°, and even more preferably greater than 60°.

[0139] In a preferred embodiment, the fourth angle is between 40° and 180°, preferably between 40° and 140°, more preferably between 50° and 130°, even more preferably between 60° and 120°, even more preferably between 70° and 110°, and even more preferably between 80° and 100°.

[0140] The applicant believes that the aforementioned angle values ​​are particularly suitable for achieving an optimized clearance distribution within the tire track area to obtain the desired on-road behavior on wet surfaces and the desired off-road behavior. Specifically, the inclination of the first segment is selected to maximize off-road performance in combination with the first straight portion of the main groove, while the inclination of the second segment is selected to achieve the best trade-off regarding wear issues and the need for effective water drainage from the tire track area.

[0141] Preferably, the first segment is shorter than the second segment.

[0142] The applicant argues that the fact that the tires are used on asphalt surfaces, whether the asphalt is dry or wet, allows for the suppression of wear on the aforementioned first segment caused by the edge of the first segment slipping on the ground during slippage and during acceleration and braking.

[0143] Preferably, the first segment is shorter than the first straight section.

[0144] Preferably, the second segment is shorter than the first straight section.

[0145] Preferably, the second segment is longer than the second straight section.

[0146] Preferably, the first segments of all secondary trenches are parallel to each other.

[0147] Preferably, the first segment of all secondary trenches has the same length.

[0148] Preferably, the second segments of all secondary trenches are parallel to each other.

[0149] Preferably, the second segments of all secondary trenches have the same length.

[0150] Preferably, the plurality of secondary trenches comprise a first series of circumferentially successive secondary trenches arranged at least partially on one side relative to the equatorial plane.

[0151] Preferably, all the secondary trenches in the first series of secondary trenches are identical to each other.

[0152] Preferably, the plurality of secondary trenches include a second series of circumferentially successive secondary trenches arranged at least partially on the other side of the equatorial plane.

[0153] Preferably, all the secondary trenches in the second series of secondary trenches are identical to each other.

[0154] Preferably, the shape of the secondary trench of the second series of secondary trenches is mirror-reflected with the shape of the secondary trench of the first series of secondary trenches.

[0155] Preferably, the second series of secondary grooves is circumferentially offset relative to the first series of secondary grooves. This offset allows for the prevention of unwanted noise during tire rolling.

[0156] Preferably, each of the first series of secondary trenches is axially adjacent to the corresponding main trench of the second series of main trenches.

[0157] Preferably, each secondary trench in the second series of secondary trenches is axially adjacent to the corresponding main trench in the first series of main trenches.

[0158] Preferably, each of the first segments of the second series of secondary trenches extends in a corresponding direction intersecting with the second straight portion of the axially adjacent main trench.

[0159] Preferably, the second segment of the secondary trench in the second series of secondary trenches is substantially parallel to the second part of the main trench in the first series of main trenches.

[0160] Preferably, the second segment of the secondary trench in the second series of secondary trenches is substantially parallel to the first segment of the secondary trench in the first series of secondary trenches.

[0161] The aforementioned arrangement of the primary and secondary grooves enables the first segment of the secondary groove in the second series of secondary grooves to assist the first portion of the primary groove in the first series of primary grooves, thereby achieving the desired off-road behavior (particularly regarding the cancellation of lateral forces) for the front or rear tires when the rear tire slips on one side, and achieving the desired on-road behavior (particularly regarding the drainage of water from the tire track area) when the tires are slightly turning on the aforementioned side on a wet surface. Similarly, the first segment of the secondary groove in the first series of secondary grooves assists the first portion of the primary groove in the second series of primary grooves, thereby achieving the aforementioned desired off-road behavior for the front or rear tires when the rear tire slips on the other side, and achieving the aforementioned desired on-road behavior when the tires are slightly turning on the aforementioned other side on a wet surface.

[0162] In a first preferred embodiment, all the first segments of the secondary grooves extend until they reach the equatorial plane but do not cross it. The applicant believes that tires manufactured according to these first preferred embodiments are particularly suitable for use as rear tires for large endurance road motorcycles.

[0163] Preferably, in the first preferred embodiment described above, all the first segments of the secondary trench extend in the corresponding direction intersecting with the second straight portion of the axially adjacent main trench.

[0164] In a second preferred embodiment, all the first segments of the secondary grooves traverse the equatorial plane. The applicant believes that tires manufactured according to these second preferred embodiments are particularly suitable for use as front tires for large endurance road motorcycles. Indeed, the front tire must ensure water drainage from the tire track area so that the rear tire can travel on drier road sections. The groove segments traversing the equatorial plane are particularly advantageous for achieving this purpose.

[0165] Preferably, in the second preferred embodiment described above, all the first segments of the secondary grooves are completely arranged inside the axially inner annular portion of the tread belt, the axially inner annular portion being arranged to straddle the equatorial plane.

[0166] Preferably, the axial extension of the inner annular portion is less than 20% of the maximum width of the radial section of the tread belt, more preferably less than 15% of the maximum width of the radial section of the tread belt, and even more preferably less than 10% of the maximum width of the radial section of the tread belt.

[0167] Because of the groove segments that traverse the equatorial plane, the aforementioned axial inner annular portion has deformability to allow the front tires to absorb any unevenness in the road surface, such as road breaks, bridge connections, etc.

[0168] Preferably, the axial inner annular portion does not include other groove segments or portions other than the first segment of the secondary groove.

[0169] In certain preferred embodiments, which are preferably consistent with the second preferred embodiment described above, each of the first segments of the second series of secondary trenches extends in a corresponding direction intersecting with the first straight portion of the axially adjacent main trench.

[0170] Preferably, the tread band also includes multiple lateral grooves inclined at a fifth angle relative to the equatorial plane.

[0171] Preferably, the fifth angle is less than 90°, more preferably less than 80°, even more preferably less than 70°, and even more preferably less than 65°.

[0172] Preferably, the fifth angle is greater than 20°, more preferably greater than 30°, and even more preferably greater than 35°.

[0173] In a preferred embodiment, the fifth angle is between 20° and 90°, preferably between 20° and 80°, more preferably between 30° and 70°, and even more preferably between 35° and 65°.

[0174] Preferably, the first series of lateral grooves in the plurality of lateral grooves extends from the end edge of the tread strip toward the equatorial plane.

[0175] Preferably, the lateral trenches in the first series of lateral trenches are substantially parallel to each other.

[0176] Preferably, the second series of lateral grooves in the plurality of lateral grooves extends from the opposite end edges of the tread strip toward the equatorial plane.

[0177] Preferably, the lateral trenches in the second series of lateral trenches are substantially parallel to each other.

[0178] Preferably, the first lateral trench in the first series of lateral trenches extends along a corresponding direction that intersects with the second straight portion of the corresponding main trench.

[0179] Preferably, the first lateral trench in the second series of lateral trenches extends in a corresponding direction that intersects with the second straight portion of the corresponding main trench.

[0180] Preferably, the second lateral groove, which is circumferentially successive to the first lateral groove, extends in a corresponding direction that intersects with the first straight portion of the corresponding main groove.

[0181] Preferably, the third lateral groove, which is circumferentially successive to the second lateral groove, extends in a corresponding direction that coincides with the extension direction of the second segment of the secondary groove arranged circumferentially between the two circumferentially successive main grooves.

[0182] Preferably, the length of the first lateral trench is equal to the length of the second lateral trench.

[0183] Preferably, the third lateral trench is shorter than the first lateral trench.

[0184] Preferably, the third lateral groove is shorter than the second lateral groove. Attached Figure Description

[0185] Other features and advantages of the invention will become more apparent from the following description of some preferred embodiments of the invention with reference to the accompanying drawings. In these drawings:

[0186] - Figure 1 This is a schematic diagram of the radial section of the rear tire according to the present invention. For the sake of simplification, the tread strip without grooves is shown.

[0187] - Figure 2 This is a front view of the rear tire according to the present invention;

[0188] - Figure 3 yes Figure 2 An enlarged view of a portion of the tire;

[0189] - Figure 4 This is a front view of the front tire according to the present invention;

[0190] - Figure 5 yes Figure 4 An enlarged view of a portion of the tire. Detailed Implementation

[0191] refer to Figure 1 The motorcycle tire according to the present invention is indicated by reference numeral 1 in the accompanying drawings.

[0192] The following text refers to Figure 1 The description also applies to the case of rear tires (e.g.) Figure 2-3 As shown, and will be discussed in more detail in the remainder of this manual) and the condition of the front tires (as shown). Figure 4-5 As shown, and will be discussed in more detail in the remainder of this specification.

[0193] Tire 1 is a tire for a "large endurance" type motorcycle, which has a large piston displacement (e.g., equal to 1000 cm³) and high power (e.g., equal to 100 hp), and a mass under driving conditions of, for example, equal to 200 kg or more.

[0194] Tire 1 is intended to be mounted on a wheel rim with a mounting diameter between approximately 17 inches and approximately 21 inches (e.g., between 19 inches and 21 inches in the case of a front tire, and between 17 inches and 18 inches in the case of a rear tire).

[0195] In tire 1, the equatorial plane XX and the axis of rotation (not shown) are defined. Also defined is based on tire 1 ( Figure 2-5 The rotation direction R is arranged and is therefore parallel to the circumferential direction of the equatorial plane XX and perpendicular to the equatorial plane XX and / or parallel to the axis of rotation.

[0196] Tire 1 includes a carcass structure 2, which is formed by at least one carcass ply 3, which is made of an elastomeric material sheet, which incorporates multiple reinforcing cords (not shown) made of fibrous fabric material.

[0197] exist Figure 1 In the tire, the carcass structure 2 is of the radial type, that is, the reinforcing cords of the at least one carcass layer 3 are arranged substantially parallel to each other in the crown portion of the tire 1 at an angle relative to the circumferential direction, the angle being between 70° and 110°, more preferably between 80° and 100°, for example equal to 90°.

[0198] In an embodiment not shown, the carcass structure includes at least two carcass plies that are radially stacked on top of each other. In this case, the reinforcing cords are substantially parallel to each other in each carcass ply and are oriented in the opposite direction to the reinforcing cords of the radially adjacent (cross-ply carcass) carcass ply 3, according to the inclination direction relative to the equatorial plane of the tire and according to the opposite direction to the reinforcing cords of the radially adjacent (cross-ply carcass) carcass ply 3.

[0199] The tire carcass structure 2 is typically covered with a sealing layer 100 (so-called "lining") on its inner wall. The sealing layer is mainly composed of an air-impermeable elastomeric material layer, which is suitable for ensuring the airtightness of the tire 1 itself after inflation.

[0200] The (or each) carcass ply 3 is shaped in a generally annular configuration and its axially opposite lateral edges 3a are turned upward on their respective annular reinforcing structures 4, designed to hold the tire 1 on the corresponding mounting rim (not shown). The annular reinforcing structure 4 is commonly referred to as the "bead core".

[0201] A conical elastomeric filler 5 is applied to the outer peripheral edge of the bead core 4, occupying the space between the corresponding carcass ply 3 and the corresponding upwardly turned lateral edge 3a of the carcass ply 3.

[0202] The area of ​​tire 1 including the bead core 4 and the elastomeric filler 5 forms a so-called bead 9, which is designed to anchor tire 1 to the rim.

[0203] Preferably, the carcass reinforcement structure can be located radially outward relative to the carcass structure (whether it is a radial ply or a cross ply). The carcass reinforcement structure includes a crown ply, which is arranged radially outward relative to the outermost radial carcass ply and at least in the crown portion of the outermost radial carcass ply. The crown ply includes reinforcing elements arranged parallel to each other. The crown ply is arranged on the outermost radial carcass ply such that the reinforcing elements of the crown ply have an angle relative to the equatorial plane opposite to the angle of the reinforcing cords of the outermost radial carcass ply. Optionally, the carcass reinforcement structure includes two ply layers arranged on opposite sides of the crown ply and not connected to corresponding bead layers.

[0204] In one embodiment, the (or each) carcass ply 3 is manufactured by juxtaposing multiple strips of elastomeric material reinforced by the aforementioned reinforcing cords.

[0205] The belt structure 6 is applied circumferentially to the carcass structure 2 at a radially outward position relative to the carcass structure. The belt structure 6 includes at least one belt layer 6a, which is typically formed of fabric or metal-reinforced cords embedded in a layer of elastomeric material.

[0206] Preferably, the belt structure 6 is of the zero-degree type, that is, the belt layer 6a is made of reinforcing cords arranged substantially parallel and side by side to form multiple loops. These loops are oriented substantially in a circumferential direction (typically having an angle between 0° and 5°), which is generally defined as being laid at "zero degrees" relative to the circumferential direction of the tire 1 with reference to the loops.

[0207] The belt layer 6a, typically defined as “zero degree”, may include axially juxtaposed winding of a single cord, or axially juxtaposed winding of rubberized strip-like elements having reinforcing cords axially located on both sides.

[0208] The reinforcing cord of the zero-degree belt layer 6a is typically a metal cord made of high-carbon steel wire, i.e., steel wire with a carbon content of at least 0.6%-0.7%. Preferably, the metal reinforcing cord has a high elongation (HE).

[0209] Optionally, in some tires, such as Figure 1 In order to improve the adhesion between the belt structure 6 and the tire carcass structure 2, an adhesive layer 7 of elastomeric material can be arranged between the belt structure and the tire carcass structure.

[0210] In various embodiments, the belt structure 6 comprises two or more radially stacked belt layers, each belt layer being made of an elastomeric material incorporating reinforcing cords arranged parallel to each other. The belt layers are arranged such that the reinforcing cords of the first belt layer are oriented obliquely relative to the equatorial plane of the tire, while the reinforcing cords of radially adjacent belt layers also have an oblique but intersecting orientation relative to the reinforcing cords of the first belt layer, thus forming a so-called "cross belt." The same applies if any other possible belt layers are present. Cross belts typically comprise fabric reinforcing cords.

[0211] The tread belt 8 is stacked circumferentially on the belt layer structure 6 and is located radially outward relative to the belt layer structure 6.

[0212] During the molding operation performed in conjunction with the vulcanization step of tire 1, multiple grooves are obtained on the tread belt 8, which are oriented as described in the remainder of this specification in order to define a specific tread pattern. As already mentioned, for simplicity Figure 1 The diagram in the image does not show the aforementioned grooves.

[0213] The tread belt 8 (and other tire components not described / illustrated as they are standard parts) is made of an elastomer material.

[0214] Figure 1 The tire 1 also includes a pair of sidewalls 10, which are laterally applied to opposite sides of the tire body structure 2 and are also made of an elastomeric material.

[0215] refer to Figure 1 Tire 1 has a section height H, which is measured on the equatorial plane XX between the top of the tread strip 8 and the assembly diameter, which is identified by a reference line r passing through the bead 9 of tire 1.

[0216] refer to Figure 1 As measured on the equatorial plane XX of tire 1, tire 1 also has a maximum radial cross-sectional width C defined by the distance between the laterally opposite ends E of the tread belt 8, and an arrow f defined by the distance from the top of the tread belt 8 to the line L passing through the laterally opposite ends E. The laterally opposite ends E of the tread belt 8 may be formed with edges.

[0217] The maximum width C of the radial section of tire 1 is preferably between 90 mm and 170 mm, more preferably between 90 mm and 120 mm in the case of the front tire, and more preferably between 130 mm and 170 mm in the case of the rear tire.

[0218] Tire 1 has: a curvature ratio f / C defined by the ratio of arrow f to the maximum width C of the radial section; and an arrow-to-total-height ratio (f / H) defined by the ratio between arrow f and section height H.

[0219] Tire 1 is the rear tire (e.g.) Figure 2 and Figure 3 In the case of the rear tire shown, the arrow f is preferably between about 40 mm and about 60 mm, the curvature ratio f / C is preferably between about 0.25 and about 0.35, for example equal to about 0.26, and the ratio of the arrow to the total height f / H is preferably between about 0.40 and about 0.60, for example equal to about 0.43.

[0220] Tire 1 is the front tire (e.g.) Figure 4 and Figure 5 In the case of the front tire shown, the arrow f is preferably between about 35 mm and about 60 mm, the curvature ratio f / C is preferably between about 0.30 and about 0.40, for example equal to about 0.38, and the ratio of the arrow to the total height f / H is preferably between about 0.40 and about 0.60, for example equal to about 0.53.

[0221] refer to Figure 2 and Figure 3 The tread pattern of the tread belt 8 of a preferred embodiment of the rear tire 1 manufactured according to the present invention is described below.

[0222] The tread band 8 has a void rubber ratio greater than 10%, preferably between 10.5% and 22%, more preferably between 11% and 21%, and even more preferably between 12% and 20%, in a rear tire with a specification of 170 / 60 / R17 (such as, for example...). Figure 2 and Figure 3 In the case of the rear tire shown, the void ratio is, for example, equal to 14.5%, while in the case of the front tire with a specification of 120 / 70 / R19 (e.g. Figure 4 and Figure 5 In the case of the front tire shown, the void rubber ratio is, for example, equal to 16.5%.

[0223] like Figure 2 As shown, the tread band 8 includes: a first series of circumferentially successive main grooves 20, which are arranged on one side relative to the equatorial plane XX; and a second series of circumferentially successive main grooves 60, which are arranged on the opposite side relative to the equatorial plane XX and circumferentially offset relative to the first series of main grooves 20.

[0224] The main grooves 20 are identical to each other.

[0225] The main grooves 60 are identical to each other, and their shapes are mirror reflections of the shapes of the main grooves 20.

[0226] The tread band 8 also includes: a first series of circumferentially successive secondary grooves 30, which are arranged on one side relative to the equatorial plane XX, particularly on the same side as the main grooves 20; and a second series of circumferentially successive secondary grooves 70, which are arranged on the opposite side relative to the equatorial plane XX and are therefore on the same side as the second series of main grooves 60 and circumferentially offset relative to the first series of secondary grooves 30.

[0227] Each secondary trench 30 is arranged between two circumferentially successive main trenches 20 and axially adjacent to the corresponding main trench 60. Similarly, each secondary trench 70 is arranged between two circumferentially successive main trenches 60 and axially adjacent to the corresponding main trench 20.

[0228] The secondary trenches 30 are identical to each other.

[0229] The secondary trenches 70 are identical to each other and their shapes are mirror reflections of the secondary trenches 30.

[0230] The tread band 8 also includes: a plurality of circumferentially successive lateral grooves 41, 42, 43 arranged on one side relative to the equatorial plane XX, particularly located on the same side as the main groove 20 and the secondary groove 30; and a plurality of circumferentially successive lateral grooves 81, 82, 83 arranged on the opposite side relative to the equatorial plane XX, thus located on the same side as the main groove 60 and the secondary groove 70.

[0231] Lateral grooves 81, 82, and 83 are circumferentially offset relative to lateral grooves 41, 42, and 43.

[0232] like Figure 3 As shown, each main trench 20, 60 includes a corresponding first straight portion 21, 61, the first straight portion having a corresponding end 21a, 61a close to the equatorial plane XX and an opposite end 21b, 61b away from the equatorial plane XX.

[0233] The first straight portion 21, 61 of each main groove 20, 60 has a width L1, which gradually increases from the end 21a, 61a to the opposite end 21b, 61b.

[0234] The ends 21a, 61a of the first straight portion 21, 61 of each main groove 20, 60 are arranged at a distance D1 from the equatorial plane, the distance D1 being between 3% and 12% of the maximum radial width C of the tread strip 8, preferably between 5% and 10% of the maximum radial width C of the tread strip 8.

[0235] The ends 21b, 61b of the first straight portion 21, 61 of each main groove 20, 60 are arranged at a distance D2 from the equatorial plane, the distance D2 being between 10% and 30% of the maximum radial width C of the tread strip 8, preferably between 15% and 25% of the maximum radial width C of the tread strip 8.

[0236] The first straight portions 21, 61 of each main groove 20, 60 are inclined at an angle α relative to the equatorial plane. In a particularly preferred embodiment of the tire 1, the angle α is less than 45°, preferably less than 35°, and even more preferably less than 30°.

[0237] In a preferred embodiment of tire 1 (e.g.) Figure 2 and Figure 3 In the embodiment shown, the first straight portions 21 of all main trenches 20 are substantially parallel to each other. Similarly, the first straight portions 61 of all main trenches 60 are substantially parallel to each other.

[0238] Each main groove 20, 60 also includes a corresponding second straight portion 22, 62, which extends from the end 21b, 61b of the corresponding first straight portion 21, 61 toward the equatorial plane XX and is inclined at an angle β relative to the first straight portion 21, 61 of the corresponding main groove 20, 60. In a particularly preferred embodiment of the tire 1, the angle β is between 90° and 160°, preferably between 95° and 150°, more preferably between 100° and 145°, and even more preferably between 100° and 140°.

[0239] In a preferred embodiment of tire 1 (e.g.) Figure 2 and Figure 3 In the embodiment shown, the second straight portions 22 of all main trenches 20 are substantially parallel to each other. Similarly, the second straight portions 62 of all main trenches 60 are also substantially parallel to each other.

[0240] Each second straight section 22, 62 has a corresponding end 22a, 62a close to the equatorial plane XX and an opposite end 22b, 62b away from the equatorial plane XX and connected to or overlapping with the end 21b, 61b of the corresponding first straight section 21, 61.

[0241] The ends 22a and 62a of the second straight portions 22 and 62 of each main groove 20 and 60 are arranged at a distance XX from the equatorial plane, the distance being between 3% and 12% of the maximum radial width C of the tread strip 8, preferably between 5% and 10% of the maximum radial width C of the tread strip 8.

[0242] Preferably, such as Figure 2 and Figure 3 As shown in the example, this distance is equal to the aforementioned distance D1.

[0243] The second straight portions 22 and 62 of the main grooves 20 and 60 are shorter than the first straight portions 21 and 61. In a particularly preferred embodiment of the tire 1, the length of the second straight portions 22 and 62 is less than half the length of the first straight portions 21 and 61, preferably less than or equal to one-third the length of the first straight portions 21 and 61.

[0244] Each main groove 20 includes an edge portion defined at an end 21a that overlaps in the axial direction with an edge portion defined at an end 62a of the corresponding main groove 60.

[0245] Each main groove 20 also includes an edge portion defined at an end 22a, which overlaps in the axial direction with an edge portion defined at an end 61a of the corresponding main groove 60.

[0246] The circumferential extension of the overlapping edge portion of the main groove 20 and the main groove 60 in the axial direction is preferably less than 20% of the circumferential extension of the main grooves 20 and 60, and more preferably less than 15% of the circumferential extension of the main grooves 20 and 60.

[0247] The circumferential extension of secondary trenches 30 and 70 is less than that of primary trenches 20 and 60.

[0248] In a preferred embodiment of tire 1, the circumferential extension of the secondary grooves 30 and 70 is less than 50% of the circumferential extension of the main grooves 20 and 60, more preferably less than 40% of the circumferential extension of the main grooves 20 and 60, and even more preferably less than 30% of the circumferential extension of the main grooves 20 and 60.

[0249] Each secondary groove 30, 70 includes a first segment 31, 71 (preferably a straight segment) and a second segment 32, 72 (also preferably a straight segment), the second segment extending from the first segment 31, 71 toward the corresponding end edge 8a, 8b of the tread strip 8, but not extending to the corresponding end edge.

[0250] Each secondary groove 30, 7 has a generally V-shaped shape, wherein the first segments 31, 71 define one arm of the V, the second segments 32, 73 define the other arm of the V, and the apex of the V is oriented relative to the first arm 31, 71 and the second arm 32, 72 in the same direction of rotation of the tire 1.

[0251] The apex of the secondary groove 30 is located at a distance between D1 and D2 from the equatorial plane XX. That is, relative to the ends 21a and 22a of the main groove 20, this apex is at the outermost position in the axial direction, while relative to the ends 21b and 22b of the main groove 20, this apex is at the innermost position in the axial direction. Similarly, the apex of the secondary groove 70 is also located at a distance between D1 and D2 from the equatorial plane XX. That is, relative to the ends 61a and 62a of the main groove 60, this apex is at the outermost position in the axial direction, while relative to the ends 61b and 62b of the main groove 60, this apex is at the innermost position in the axial direction.

[0252] The first segments 31 and 71 are shorter than the second segments 32 and 72 and extend toward the equatorial plane XX until the first segment reaches the equatorial plane, but do not cross the equatorial plane.

[0253] The length of the first segment 31 and 71 is greater than half the length of the second segment 32 and 72.

[0254] The first segments 31 and 71 and the second segments 32 and 72 are both shorter than the first straight line portion 21 and 61.

[0255] The second segment 32 and 72 are longer than the second straight line segment 22 and 62.

[0256] The first segments 31, 71 of each secondary trench 30, 70 are inclined at an angle γ relative to the equatorial plane XX, said angle γ being between 90° and 180°, more preferably between 100° and 170°, even more preferably between 110° and 160°, and even more preferably between 120° and 140°.

[0257] The second segments 32, 72 of each secondary trench 30, 70 are inclined at an angle δ relative to the first segments 31, 71 of the corresponding secondary trench 30, 70. The angle δ is between 40° and 180°, preferably between 40° and 140°, more preferably between 50° and 130°, even more preferably between 60° and 120°, even more preferably between 70° and 110°, and even more preferably between 80° and 100°.

[0258] In a preferred embodiment of tire 1, for example Figure 2 and Figure 3 In the illustrated embodiment, the first segments 31 of all secondary trenches 30 are substantially parallel to each other. The first segments 31 are also substantially parallel to the second straight portion 22 of the main trench 20 and the second segment 72 of the secondary trench 70. Similarly, the first segments 71 of all secondary trenches 70 are substantially parallel to each other. The first segments 71 are also substantially parallel to the second straight portion 62 of the main trench 60 and the second segment 32 of the secondary trench 30.

[0259] The second segments 32 of all secondary trenches 30 are substantially parallel to each other. The second segments 32 are also substantially parallel to the second straight portion 62 of the main trench 60 and the first segment 71 of the secondary trenches 70. Similarly, the second segments 72 of all secondary trenches 70 are substantially parallel to each other and substantially parallel to the second straight portion 22 of the main trench 20 and the first segment 31 of the secondary trenches 30.

[0260] Each of the first segments 31 of the secondary trench 30 extends in a corresponding direction intersecting the second straight portion 62 of the axially adjacent main trench 60. Similarly, each of the first segments 71 of the secondary trench 70 extends in a corresponding direction intersecting the second straight portion 22 of the axially adjacent main trench 20.

[0261] Lateral grooves 41, 42, and 43 are basically parallel to each other and extend from the end edge 8a of the tread band 8 toward the equatorial plane XX.

[0262] The lateral grooves 81, 82, and 83 are substantially parallel to each other and extend from the opposite end edge 8b of the tread band 8 toward the equatorial plane XX.

[0263] Lateral grooves 41, 42, 43 and 81, 82, 83 are inclined at an angle θ relative to the equatorial plane XX, said angle θ being between 20° and 90°, preferably between 20° and 80°, more preferably between 30° and 70°, and even more preferably between 35° and 65°.

[0264] Lateral groove 41 extends in a corresponding direction that intersects with the second straight portion 22 of the corresponding main groove 20. Similarly, lateral groove 81 extends in a corresponding direction that intersects with the second straight portion 62 of the corresponding main groove 60.

[0265] Each lateral trench 42 is circumferentially successive to the corresponding lateral trench 41 and extends in a direction intersecting the first straight portion 21 of the corresponding main trench 20. Similarly, each lateral trench 82 is circumferentially successive to the corresponding lateral trench 81 and extends in a direction intersecting the first straight portion 61 of the corresponding main trench 60.

[0266] Each lateral trench 41 and the circumferentially successive lateral trench 42 intersect with the same main trench 20. Similarly, each lateral trench 81 and the circumferentially successive lateral trench 82 intersect with the same main trench 60.

[0267] Each lateral trench 43 extends circumferentially in succession to the corresponding lateral trench 42 and in a direction that coincides with the direction in which the second segment 32 of the secondary trench 30, which is circumferentially successive to the main trench 20, extends. Similarly, each lateral trench 83 extends circumferentially in succession to the corresponding lateral trench 82 and in a direction that coincides with the direction in which the second segment 72 of the secondary trench 70, which is circumferentially successive to the main trench 60, extends.

[0268] Lateral grooves 41, 42, 81, and 82 have essentially the same length, while lateral grooves 43 and 83 are shorter than lateral grooves 41, 42, 81, and 82.

[0269] Lateral grooves 41 and 42 extend partially within an annular portion of the tread band 8, which also includes a second segment 32 of the secondary groove 30. Similarly, lateral grooves 81 and 82 extend partially within an annular portion of the tread band 8, which also includes a second segment 72 of the secondary groove 70. These annular portions are defined at a distance greater than D2 from the equatorial plane XX.

[0270] refer to Figure 4 and Figure 5 The following describes the tread pattern of the tread belt 8 of a preferred embodiment of the front tire 1 manufactured according to the present invention.

[0271] Except as described below, the description of this tread pattern is consistent with the above reference. Figure 2 and Figure 3 The descriptions are identical. Therefore, avoid repeating the same parts described above. The following only describes... Figure 4 and Figure 5 Tire 1 and Figure 2 and Figure 3 There are differences in characteristics between tires.

[0272] exist Figure 4 and Figure 5 In the tread belt 8 of the tire 1, the main grooves 20 and 60 overlap along the axial direction at corresponding locations, and the circumferential extension of the corresponding locations is between 10% and 50% of the circumferential extension of each main groove 20 and 60, more preferably between 20% and 50% of the circumferential extension of each main groove 20 and 60, and even more preferably between 30% and 50% of the circumferential extension of each main groove 20 and 60.

[0273] exist Figure 4 and Figure 5 In the tread belt 8 of the tire 1, the first segments 31 and 71 of the secondary grooves 30 and 70 cross the equatorial plane XX and are completely arranged inside the axial inner annular portion 80 of the tread belt 8.

[0274] The axial inner annular portion 80 is defined to straddle the equatorial plane XX and the axial extension A is less than 20% of the maximum radial cross-sectional width C of the tread belt 8, preferably less than 15% of the maximum radial cross-sectional width C of the tread belt 8.

[0275] The axial inner annular portion 80 does not include any other groove segments or portions other than the first segments 31 and 71 mentioned above.

[0276] exist Figure 4 and Figure 5 In the tread belt 8 of tire 1, the length of the first segment 31, 71 is less than or equal to half the length of the second segment 32, 72.

[0277] exist Figure 4 and Figure 5 In the tread belt 8 of the tire 1, the vertex of the V formed by each secondary groove 30, 70 is oriented in the opposite direction to the rotation direction of the tire 1 relative to the first arm 31, 71 and the second arm 32, 72, and the vertex is arranged at the innermost position in the axial direction relative to the ends 22a, 62a of the main grooves 20, 60.

[0278] exist Figure 4 and Figure 5 In the tread belt 8 of the tire 1, the first segment 31 of each secondary groove 30 extends in the direction intersecting with the first straight portion 61 of the main groove 60 adjacent to the axial direction.

[0279] exist Figure 4 and Figure 5 In the tread belt 8 of the tire 1, the second segment 32 of the secondary groove 30 and the lateral grooves 41, 42 extend at different annular portions of the tread belt 8. Similarly, the second segment 72 of the secondary groove 70 and the lateral grooves 81, 82 extend at different annular portions of the tread belt 8.

[0280] Comparative Test

[0281] The applicant has manufactured a sample of a rear tire 1 according to an embodiment of the present invention, the sample having in particular... Figure 2 and Figure 3 The tire tread pattern shown is shown below. In the following text, this tire is designated "INV".

[0282] The tire INV has the same structure and dimensions as a large endurance rear tire (hereinafter referred to as Ref) currently sold by the applicant in the market. The tire Ref has been approved for use in combination with highway travel and dirt roads, and therefore belongs to the same market segment as the tire INV.

[0283] Outdoor comparative tests were conducted using the tire Ref, and customers praised its excellent performance on both dry and wet surfaces, as well as its absolutely satisfactory off-road capabilities.

[0284] The test was conducted by mounting tire INV and tire Ref on the rear wheel of a BMW R1250GS motorcycle (inflated at the same pressure) and the same tire on the front wheel, and under substantially the same environmental conditions.

[0285] The performance of both INV and Ref tires was evaluated in both on-road (dry and wet) and off-road conditions, and rider feedback was solicited. In particular, the items listed in Table 1 of the report below were evaluated, and rider feedback is also reported.

[0286] Highway testing is conducted on routes that include both straight sections and curves (both of which involve dry and wet surfaces).

[0287] Off-road tests were performed by driving several times along a straight route of fixed length, prepared with mud and sand simulating possible conditions found in the natural environment, with the terrain kept as homogeneous as possible after each test. Two sensors were installed on the straight route to determine the entry and exit times of the motorcycle, which was equipped with appropriate tools (GPS sensor, engine throttle opening sensor, and speed sensors for both wheels).

[0288] INV Ref Stability on a straight line = = Cornering stability = = Driving ease = = Line maintenance + = Grip + = Light off-road = =

[0289] Table 1

[0290] In Table 1, “=" indicates a positive rating obtained using the tire Ref, and “+” indicates an improvement relative to the tire Ref.

[0291] Table 1 shows that tire INV demonstrates improved performance on paved roads related to line retention and grip (and therefore acceleration and braking) compared to tire Ref, while tire INV performs consistent with tire Ref for all other evaluation items (including light off-road). Thus, the applicant demonstrates that the specific tread pattern employed in the tire of this invention effectively allows for the desired improvements in acceleration and braking performance on both dry and wet paved roads, while maintaining the same good off-road performance as tire Ref.

[0292] Of course, those skilled in the art can make further modifications and alterations to the tires of the above invention to meet specific and situation-dependent application needs, and such modifications and alterations shall in any case fall within the protection scope defined by the following claims.

Claims

1. A motorcycle tire (1), the motorcycle tire comprising a tread belt (8) having a plurality of main grooves (20; 60) arranged on opposite sides relative to the equatorial plane (XX) of the motorcycle tire (1) and a void rubber ratio greater than 10%, wherein, The main trench (20; Each of the following is included in 60): - A first straight portion (21; 61) is inclined at a first angle (α) of less than 45° relative to the equatorial plane (XX), and the first straight portion has a first end (21a; 61a) close to the equatorial plane (XX) and a second end (21b; 61b) away from the equatorial plane (XX); - A second straight section (22; 62) is inclined at a second angle (β) between 90° and 160° relative to the first straight section (21; 61), and the second straight section has a third end (22a; 62a) close to the equatorial plane (XX) and a fourth end (22b; 62b) away from the equatorial plane (XX). The second straight section (22; 62) is shorter than the first straight section (21; 61).

2. The motorcycle tire (1) according to claim 1, wherein, The length of the second straight section (22; 62) is less than half the length of the first straight section (21; 61).

3. The motorcycle tire (1) according to claim 1 or 2, wherein, The width of the first straight portion (21; 61) gradually increases from the first end (21a; 61a) to the second end (21b; 61b).

4. The motorcycle tire (1) according to any one of the preceding claims, wherein, The first end (21a; 61a) and the third end (22a; 62a) are arranged at a corresponding distance (D1) from the equatorial plane (XX) that is less than 12% of the maximum width (C) of the radial section of the tread strip (8).

5. The motorcycle tire (1) according to any one of the preceding claims, wherein, The tread band (8) includes a plurality of secondary grooves (30; 70) with a circumferential extension shorter than that of the primary grooves (20; 60). Each of the secondary grooves (30; 70) is arranged between two circumferentially successive primary grooves (20; 60) and includes a first segment (31; 71) and a second segment (32; 72). The first segment extends toward the equatorial plane (XX), and the second segment extends from the first segment (31; 71) toward but does not reach the end edges (8a; 8b) of the tread band (8).

6. The motorcycle tire (1) according to claim 5, wherein, The first segment (31; 71) is inclined at a third angle (γ) between 90° and 180° relative to the equatorial plane (XX), and the second segment (32; 72) is inclined at a fourth angle (δ) less than 180° relative to the first segment (31; 71).

7. The motorcycle tire (1) according to claim 5 or 6, wherein: - The plurality of main trenches (20; 60) include: a first series of main trenches (20) arranged in a circumferential sequence on one side relative to the equatorial plane (XX); and a second series of main trenches (60) arranged in a circumferential sequence on the other side relative to the equatorial plane (XX). - The plurality of secondary trenches (30; 70) include: a first series of circumferentially successive secondary trenches (30) arranged at least partially on one side relative to the equatorial plane (XX); and a second series of circumferentially successive secondary trenches (70) arranged at least partially on the other side relative to the equatorial plane (XX). In this series, each of the secondary trenches (30) in the first series of secondary trenches (30) is axially adjacent to the corresponding main trench (60) in the second series of main trenches (60), and each of the secondary trenches (70) in the second series of secondary trenches (70) is axially adjacent to the corresponding main trench (20) in the first series of main trenches (20).

8. The motorcycle tire (1) according to any one of claims 5 to 7, wherein, All the first segments (31; 71) of the secondary trench (30; 70) extend until the first segment reaches the equatorial plane (XX) but does not cross the equatorial plane.

9. The motorcycle tire (1) according to any one of claims 5 to 7, wherein, All the first segments (31; 71) of the secondary trench (30; 70) traverse the equatorial plane (XX).

10. The motorcycle tire (1) according to claim 9, wherein, All the first segments (31; 71) of the secondary grooves (30; 70) are completely arranged inside the axially inner annular portion (80) of the tread band (8), the axially inner annular portion being arranged to straddle the equatorial plane (XX) and having an axial extension (A) less than 20% of the maximum radial cross-sectional width (C) of the tread band (8).

11. The motorcycle tire (1) according to claim 9 or 10 when subordinate to claim 7, wherein, The first segment (31) of the secondary trench (30) in the first series of secondary trenches (30) extends in a corresponding direction intersecting the first straight portion (61) of the axially adjacent main trench (60), and the first segment (71) of the secondary trench (70) in the second series of secondary trenches (70) extends in a corresponding direction intersecting the second straight portion (22) of the axially adjacent main trench (20).

12. The motorcycle tire (1) according to any one of the preceding claims, wherein, The tread band (8) further includes a plurality of lateral grooves (41, 42, 43; 81, 82, 83) inclined at a fifth angle (θ) of less than 90° relative to the equatorial plane (XX), wherein a first series of lateral grooves (41, 42, 43) of the plurality of lateral grooves (41, 42, 43; 81, 82, 83) extends from the end edge (8a) of the tread band (8) toward the equatorial plane (XX), and a second series of lateral grooves (81, 82, 83) of the plurality of lateral grooves (41, 42, 43; 81, 82, 83) extends from the opposite end edge (8b) of the tread band (8) toward the equatorial plane (XX).

13. The motorcycle tire (1) according to claim 12 when it is subordinate to any one of claims 5 to 11, wherein, The first lateral trench (41; 81) in the first series of lateral trenches (41, 42, 43) or the second series of lateral trenches (81, 82, 83) extends along a corresponding direction intersecting the second straight portion (22; 62) of the corresponding main trench (20; 60). The second lateral trench (42; 82) that is circumferentially successive to the first lateral trench (41; 81) extends along a corresponding direction intersecting the first straight portion (21; 61) of the corresponding main trench (20; 60). The third lateral trench (43; 83) that is circumferentially successive to the second lateral trench (42; 82) extends along a corresponding direction coinciding with the extension direction of the second segment (32; 72) of the secondary trench (30; 70) circumferentially arranged between the two circumferentially successive main trenches (20; 60).

14. The motorcycle tire (1) according to claim 13, wherein, The length of the first lateral groove (41; 81) is equal to the length of the second lateral groove (42; 82).

15. The motorcycle tire (1) according to claim 13 or 14, wherein, The third lateral trench (43; 83) is shorter than both the first lateral trench (41; 81) and the second lateral trench (42; 82).

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