Method of maintaining a tire

Abstract

Method for measuring a tire comprising a substantially continuous shoulder block and at least two substantially circumferential grooves, a database associating tires and geometric data, comprising an identification of two points located in the grooves directly to determine a third point from which a measurement of distance to the rolling surface is made, this distance being compared to a threshold to launch a maintenance operation. Figure for the abstract: Fig 1

Description

Title of the invention: Method of maintaining a tire Field of invention

[0001] The invention relates to a method for measuring the wear of a tire, and more precisely this method makes it possible to measure the wear of a continuous shoulder block of a tire, the purpose of which is to plan a maintenance operation of said tire. This measurement may concern certain tires for heavy goods vehicles, certain sports touring tires whose shoulder blocks are continuous, but mainly concerns airplane tires. Technological background

[0002] The tire has a substantially toric shape around an axis of revolution coinciding with the axis of rotation of the tire. This axis of revolution defines three directions conventionally used by those skilled in the art: an axial direction, a circumferential direction and a radial direction.

[0003] By axial direction is meant the direction parallel to the axis of revolution of the tire, i.e. the axis of rotation of the tire.

[0004] By circumferential direction is meant the direction which is perpendicular to both the axial direction and a radius of the tire.

[0005] By radial direction is meant the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and perpendicular to this axis.

[0006] By meridian plane is meant a plane containing the axis of rotation of the tire.

[0007] By radially inner, respectively radially outer, is meant closer to the axis of rotation of the tire, respectively further from the axis of rotation of the tire. By axially inner, respectively axially outer, is meant closer to the median plane of the tire, respectively further from the median plane of the tire.

[0008] By median plane of the tire is meant the plane perpendicular to the axis of rotation of the tire and which passes through the axial center of the tread.

[0009] Usually, the tire is provided with a carcass reinforcement which comprises at least one carcass layer, textile or metallic, coated with a polymer. The carcass reinforcement is surmounted radially by a crown reinforcement comprising one or more crown layers, this crown reinforcement itself being surmounted by a tread.

[0010] A tire is provided with a tread having a rolling surface intended to be in contact with the road. By "rolling surface" of the tread, we mean the surface which groups together all the points of the tire which will come into contact with a ground under normal rolling conditions. The tread also includes a thickness of rubber to be worn between the rolling surface and the most radially outer point of the wear indicators. This tread includes incisions in the substantially axial or circumferential or oblique directions. A substantially circumferential incision making the entire perimeter of the tire and of a width at least equal to 5 mm is a circumferential groove. The shoulder block is the part of the tire delimited by the axial end of the tread and the most axially outer groove.

[0011] In use, the tread wears by a phenomenon of sliding with the ground. The new tread height decreases to a threshold determined by a standard or the manufacturer and which defines the moment when the tire must be changed. In the specific case of aircraft tires, patent application FR3060821-A1 mentions that the shoulder block of the tire wears particularly during the so-called taxi phases of the aircraft. Taxi phases correspond to the use preceding takeoff or following landing. The wear of the shoulder block becomes the predominant wear mechanism during this phase and therefore requires the implementation of a measure.

[0012] It is necessary for the transport professional to manage, in the most efficient way possible, a maintenance operation linked to wear. This maintenance operation consists, at a minimum, of removing the tire and replacing it in order to keep the vehicle in a condition that complies with technical and safety requirements. For example, early removal of the tire will negatively impact the profitability of an operator and, on the contrary, removal that is too late can lead to regulatory or even safety non-compliance, immobilizing the vehicle.

[0013] The tread rests on a crown reinforcement which comprises a superposition of crown layers extending circumferentially, radially outside a carcass reinforcement of the tire. Each crown layer is made up of metal or textile reinforcements parallel to each other and coated with a polymeric material of the elastomer type or coating mixture. In the particular case of excessive wear, the appearance of a crown layer, in the region of the shoulder block, will require immediate disassembly and in fact not provided for in the maintenance plan. This effect will lead to additional costs linked to the lack of availability of the vehicle, it is therefore imperative to prevent this situation by setting up a predictive maintenance plan by the professional.

[0014] Several methods exist to enable a wear diagnosis. There are wear indicators which are visible references located in the bottom of a groove. These indicators require a visual inspection by the user or the person in charge of maintenance. Each wear indicator provides a localized check near the indicator itself. Proximity is defined as a circle with a radius of approximately 5 mm around the indicator. There are also tools for measuring the remaining rubber height, for example a depth gauge. The depth gauge measures the tread height between the bottom of the groove and at least one contact on the rolling surface around the groove.

[0015] When new, the tread height of the tire is at its maximum. A wear ratio can thus be defined as the ratio between the measured tread height and the tread height when new. This same ratio is then used to define a wear rate such that the wear rate is equal to the wear ratio, which is subtracted from 1. This wear rate determines the quantity of rubber remaining to be worn.

[0016] The shoulder block of the tire and in particular the shoulder block of an aircraft tire is substantially continuous around the circumference of the tire. Substantially continuous means that a depth gauge cannot be used or that no visual wear indicator is present or that no incision more than 2 mm wide is present, this type of incision making it possible to position wear indicators. The tire and its crown reinforcement will deform plastically depending on use. This is particularly true for tires made of textile plies such as aircraft tires, and more particularly true when the reinforcement is subjected to high thermal, load, speed and pressure constraints such as aircraft tires. Remember that aircraft tires can be inflated to 15 b, reach speeds above 300 km / h and reach local temperatures above 120°C.This plastic deformation, combined with the fact that no reference groove is accessible at the shoulder, prevents a reliable measurement of the wear of the continuous shoulder block based on the relative radii of the rolling surface at the shoulder. Under these conditions, it is not possible to differentiate in the variation of the profile of the shoulder block the part of wear and the part of plastic deformation. This problem does not exist for the other blocks of the surface, wear indicators, linked to a reference groove and close to the area to be controlled, undergo the same plastic deformation of the crown reinforcement as the blocks adjacent to it. A reference groove is understood to be an area allowing the reception of a wear indicator or a depth gauge which does not come into contact with the ground, and which therefore does not wear.

[0017] The present invention aims to provide a method for measuring the wear of a tire at a substantially continuous shoulder block by taking into account the plastic deformation of the tire with use. Description of the invention

[0018] This objective was achieved by implementing a method for measuring the shoulder wear of a tire:

[0019] The tire comprising a tread comprising a rolling surface intended to come into contact with the ground,

[0020] The tread comprising at least one substantially continuous shoulder block and at least two substantially circumferential grooves,

[0021] The method using a database associating types of tires and geometric data of these tires, at least one measuring tool and comprising the following steps: • Identification with a measuring tool of a first point A located in the groove directly adjacent to the shoulder block, substantially continuous, said first point being the most radially inner point of said groove, • Identification with a measuring tool of a second point B located in the groove directly adjacent to the groove directly adjacent to the shoulder block, substantially continuous, said second point being the most radially inner point of said groove and positioned in the same meridian plane as the first point A, • We identify the type of tire, • The database associates a distance with the tire type allowing a third point RI to be positioned on the line (A, B) joining the first two points, RI being axially outside the first point A, • A measuring tool allows the identification on the tire of a fourth point II positioned in the same meridian plane as the first point A, said point being a projection of the third point RI on the rolling surface of the tire, • Determination of the distance Dl, called the first threshold distance, between the third point RI and the fourth point IL

[0022] The thickness of elastomer between the groove bottom and the radially outermost crown layer is not deformed by the stresses of use and does not wear, because it does not come into contact with the ground. This reference thickness is stable throughout the life of the tire, and in particular for the use of an aircraft tire. This thickness is also subject to plastic deformations of the crown reinforcement like the rest of the tread, the groove bottom is thus a reliable and accessible reference point for measuring the wear of a tire. Used as a reference, the groove bottoms allow not to be disturbed by the plastic deformation of the crown architecture. Thus, the use of a straight line passing through the bottom of at least two grooves gives a reliable reference for said wear measurement and at the same time allows the measurement point to be shifted into an inaccessible area. as a substantially continuous shoulder block. The method therefore consists of referring to the straight line passing through the groove bottoms of the grooves closest to the shoulder block, to position the RI point according to the type of tire, preferably at the end of the crown reinforcement always so that the plastic deformation of the reinforcement is taken into account. This positioning is virtual, because this RI point is inside the tread, nevertheless it is possible, from a profile of the tread surface including the grooves, to trace A, B and RI on a sheet if necessary. The position of the RI point therefore depends on the architecture of the tire and therefore its type, its brand, its dimension. This distance is preferably defined by the manufacturer.If this distance is not defined by the manufacturer, the RI point will be positioned on the line (A,B), axially outside point A, and more preferably at the end of the most radially outer crown layer of the crown reinforcement from measurements made on a meridian section. The database contains, depending on the tire type, an associated distance that allows the RI point to be positioned independently of the crown reinforcement architecture. By tire type, we mean data that characterizes the product such as the brand, the dimension, the commercial name or a product code. The product code comes from a tire manufacturer reference or a customer reference. The method then consists of defining a point II, as a projection of RI on the tread surface, in the same meridian plane as point A. The projection is oriented axially outside, and radially outside point A.The projection preferably makes an angle of less than 30° with the radial direction, and more preferably the projection is made in a substantially radial direction. The orientation of the projection of an angle of less than 30° makes it possible to locate the wear control in a region particularly sensitive to wear of the shoulder block. By substantially radial is meant a direction inclined by a maximum of 5° relative to the axis of the radial projection of the point RL.

[0023] The first threshold distance D1 is the remaining height of elastomer at the level of the continuous shoulder block, and preferably located at the end of the most radially outer crown layer of the crown reinforcement.

[0024] In a particular embodiment, a mechanical measuring tool that does not require a profile measurement is used. The mechanical tool rests on the two groove bottoms adjacent to the substantially continuous shoulder block. In a second step, a sensor is moved in the outer axial direction, starting from the first support point located in the groove directly adjacent to the shoulder block, by a distance dependent on the type of tire. The sensor, integral with a depth gauge, rests on the rolling surface at the substantially continuous shoulder block and allows direct measurement, by the feeler, of the sculpture height corresponding to the distance between RI and II, called first threshold distance Dl.

[0025] In a particular embodiment of said measuring method, there are at least two points, the most radially inner in at least one of the grooves. Under these conditions, information from the database which associates with the type of tire a rule making it possible to determine the point to be chosen. In the absence of a database, the point located most in the center of the groove is chosen.

[0026] In a particular embodiment of said measuring method, the point RI is located outside the profile of the rolling surface. By outside is meant the fact that the point RI is outside the components of the tire. In this case, the tread height D1 is negative. If the point RI is located substantially on the profile of the rolling surface then the measurement is equal to zero.

[0027] In an advantageous and optional embodiment, the method is completed by the steps comprising: • The database associates with the type of tire a second distance and an angle DA allowing a fifth point R2 to be positioned on the line, called the second line, passing through the third point RI and making an angle equal to DA with the line (A, B), R2 is positioned in the same meridian plane as point A, axially outside and radially inside RI, • A maintenance tool allows the identification on the tire of a distance, in the meridian plane including the first point A, said distance D2 is the distance from the fifth point R2 to the rolling surface (3).

[0028] The wear profile of the shoulder block becomes, under certain conditions of use, particularly irregular. Such wear profiles may appear in particular if the tire is not used under typical conditions of use such as inflation below or above the recommendations, excessive braking. Under these particular conditions of use, the mass of elastomer radially inside the line (A, B) of the substantially continuous shoulder block, wears at least as quickly as the mass of elastomer present radially outside the line (A, B) of the same substantially continuous shoulder block. It is advantageous to supplement said method by making it possible to quantify this wear, in this particular zone of the substantially continuous shoulder block.To do this, it is appropriate to define a second reference line linked to RL. Advantageously, the second line intersects the line (A,B) by the point RI and thus makes it possible to maintain a reliable reference on the groove bottoms which are not disturbed by the plastic deformation of the crown architecture. Preferably, the second line is substantially parallel to the line passing through the axial ends of the crown layers whose axial width is greater than the axial width of the most radially outer crown layer, in order to decorrelate the deformation. plastic formation of the top of the tread compound wear in this area. Point RI and the second straight line can also be determined from the axial ends of the crown layers if the information is not available in the database. In addition to the data needed to position point RI, the database contains an angle for orienting the second straight line and a second distance for positioning point R2 on this second straight line. Also advantageously, this second point R2 positioned in an area axially outside and radially inside RI makes it possible to explore the substantially continuous part of the shoulder block located radially inside the line (A,B). The method then consists of defining a point 12, as a projection of R2 onto the tread surface, in the same meridian plane as point A.The projection is oriented axially outwards, and preferably oriented at an angle less than 30° with the direction perpendicular to the second straight line and more particularly substantially perpendicular to the second straight line. Orienting the projection at an angle less than 30° improves the accuracy of the measurement, particularly when using a mechanical tool such as the feeler of a depth gauge. For this purpose, a feeler has a telescopic axis, which is preferable to be oriented generally in line with the surface to be measured to eliminate the risk of arching of said axis and to minimize the error linked to a rounded shape of the contact point of the feeler. Since the contact point is not strictly the same depending on the different inclinations of the feeler relative to the rolling surface, a measurement error is induced by this mechanism.By substantially perpendicular, we mean a direction inclined by a maximum of 5° around the axis of the perpendicular projection of point R2. In a final step, distance D2 is defined as a distance representative of the wear corresponding to the remaining height of elastomer at the level of the continuous shoulder block.

[0029] In a particular embodiment, the measuring tool makes it possible to record a profile of the rolling surface, in the meridian plane, including the profile of the two grooves directly adjacent to the shoulder block. Advantageously, obtaining such a profile allows, with the use of the data contained in the database, a geometric calculation of the points A, B, RI and II or even R2 and 12. This calculation can be carried out by an algorithm implemented in a maintenance management application used by the maintenance professional. This type of survey is known for example in document EP3028262.

[0030] In an advantageous embodiment, the method uses a calculator and comprises the following steps: • The database associates with the tire type a first reference distance Refll or respectively a second reference distance Ref2 of the new profile (8) of the tire, relative to the third point RI or respectively relative to the fifth point R2, • The first wear rate Txl or respectively a second wear rate Tx2 is calculated from the wear ratio, calculated from DI and Refl, or respectively D2 and Ref2. "or" is here inclusive and should be understood as including either possibility, or both possibilities.

[0031] In a particular embodiment, it is advantageous for the distances DI and D2, which represent a measured elastomer height, to be normalized relative to an elastomer height available when the tire is new. It thus becomes easier for the tire maintenance professional to interpret the figures from one tire to another. Two new tire elastomer heights of reference Refl and respectively Ref2 are thus defined, corresponding to the measurement of the heights Dl, and respectively D2. The database contains, in addition to the information previously cited, the new reference heights Refl and respectively Ref2 making it possible to calculate a wear rate Txl and respectively Tx2 which are defined by Txl=l-(D1 / Refl) and respectively Tx2=l-(D1 / Refl). Advantageously, the calculator allowing this calculation is directly integrated into a computer application dedicated to the tire maintenance professional.The maintenance management application can display wear rates considering values ranging from 0 to 1 or 0% to 100%, depending on the format chosen by the user.

[0032] In a particular embodiment, for a tire having a substantially continuous block at each shoulder, said method is applied to one then the other shoulder block of said tire.

[0033] Advantageously, the method applied to one shoulder can be applied strictly symmetrically to the other shoulder.

[0034] In a particular embodiment, the second groove, adjacent to the first groove adjacent to the shoulder block, is substantially centered on the median plane of the tire, thus serving as the same point B for one then the other shoulder block.

[0035] The invention also comprises a maintenance method using the measurement method according to the invention in which the maintenance method comprises the following steps: • The database associates a maintenance trigger threshold with the tire type, • A dismantling operation is triggered if the distance Dl is lower than the maintenance trigger threshold.

[0036] Advantageously, the maintenance method comprises, if the measurement method also includes the measurement of the distance D2, the following steps: • The database associates a second maintenance trigger threshold with the tire type, • A dismantling operation is triggered if distance D2 is lower than the second maintenance trigger threshold.

[0037] The professional must be able to make a decision with regard to the measured distances DI and D2 in order to trigger, if necessary, a corrective maintenance action such as changing the tire. Advantageously, the database therefore contains for each measurement point RI and respectively R2 a trigger threshold and respectively a second trigger threshold allowing a comparison of distance DI and respectively D2. If the distance DI and respectively D2 are lower than the respective thresholds of the database then a corrective maintenance action such as changing the tire is carried out.

[0038] In a particularly advantageous embodiment, the database contains at least one law of behavior of the tire, and more particularly at least one law corresponding to the wear rate of the shoulder block. This wear rate thus makes it possible, in comparison with the first measurements of DI and D2, to define a forecast maintenance date. The professional can thus anticipate the maintenance operations by planning them. The maintenance operations can be rationalized over time, and thus not only allow the optimization of maintenance costs, but also limit the time the aircraft is immobilized on the ground.

[0039] In an advantageous embodiment, the method comprises the following steps: • The tire is individually identified • A maintenance event is stored in a database which associates with the individual identification of the tire, at least one wear rate Txl or Tx2, or at least one of the distances to the surface DI or D2, • After at least two measurement events, a calculator suggests a preventive maintenance date or an immediate maintenance operation.

[0040] An individual identification of the tire makes it possible to record and associate several measurement events with a history. In addition to the measurements, the history is associated with data from among information of the tire such as: a manufacturing date, a manufacturing plant and a history of wear measurement of an area such as the shoulder block. Preferably, this history is stored in a knowledge base. By knowledge base, we mean a means for storing a set of histories associated with a set of individual tires. In a particular embodiment, this knowledge base is included in the database. Advantageously, the knowledge base which associates at least two shoulder block wear measurement events, makes it possible to determine a trend linked to the actual use of the tire. Advantageously, a predictive maintenance algorithm will use this trend to correct the forecast date and improve the accuracy of the forecast maintenance date. Thus, the professional, through a maintenance management application, which combines a database and a knowledge base, benefits from a forecast maintenance date that gains in accuracy thanks to knowledge of the actual use of the tire.

[0041] Advantageously, the knowledge base which comprises a set of measurement histories becomes a source of information for a second algorithm whose aim is to determine a behavior law, and particularly a wear rate law, and more particularly a shoulder block wear rate law. The algorithm therefore makes it possible to optimize a behavior law such as the shoulder block wear rate by taking into account the type of tire and its actual use. The wear prediction through the updating of these laws becomes more accurate over time.

[0042] Preferably, this method of maintaining a tire applies to an aircraft tire but can just as easily be applied to a heavy goods vehicle tire. Brief description of the drawings

[0043] [Fig.l] schematically represents, without scaling, a partial meridian section (5) of a crown of an aircraft tire truncated axially by the projection (7) of the median plane. The figure represents a tread (2) of a tire comprising a substantially continuous shoulder block (1) and two circumferential grooves (6). A crown reinforcement (9), radially inside the tread (2), comprises a superposition of crown layers (4) which extend in the circumferential direction. Each crown layer (4) is made up of textile or metal reinforcements coated with an elastomeric mixture. A profile of the tread surface (3) after use is represented in solid lines and a profile of a new tire (8) in broken lines.Also shown in the drawing are the most radially inner points A and B of the grooves (6) adjacent to the substantially continuous shoulder block (7), the point RI on the straight line (AB) and preferably in line with the end of the most radially outer crown layer (4) allowing the measurement of the distance DI here radial distance from RI on the contact surface (7) of the worn tire. Similarly shown is a second straight line allowing R2 to be positioned, this straight line being preferably parallel to the ends of the crown layers whose axial width is greater than the axial width of the most radially outer crown layer, the distance RI to R2 being defined either by the manufacturer or by . analysis of product wear as the most wearing point.

[0044] [Fig. 2] schematically represents, without scaling, a wear measuring tool comprising a chassis (21). This tool has two support points (23) which come into contact with the groove bottoms of the tread (2) of a tire. One of the support points (23) is integral with the chassis (21). The distance Dab separating the support points (23) can be adjusted by a groove slide (26) along the groove slide axis (22). The tool has a depth gauge (25) comprising a telescopic feeler (24). The longitudinal axis of the feeler (20) defines a substantially linear direction of movement of the telescopic feeler (24). The depth gauge (25) is connected to the chassis (21) by means of a gauge slide (27) and a secondary slide (30).The secondary slide (30) makes it possible to adjust the distance Drl between the longitudinal axis of the probe (20) and the support point (23) secured to the chassis (21) along the gauge slide axis (29). An angle Ar2 between the axis of the gauge slide (29) and the axis of the furrow slide (22) can be adjusted via a pivot connection (28) and a distance Dr2 can be adjusted by the gauge slide (27). Detailed description of embodiments

[0045] In a first embodiment, the tire maintenance professional uses a tool, as illustrated in [Fig.2], to carry out a wear check on the shoulder blocks of the tires of an A320 aircraft. The aircraft is equipped with Michelin tires of size 46 17 R20 where the information necessary for implementing the method is available in a database. In order to carry out a first measurement, the distance Drl defined in the database is adjusted. Then the maintenance professional positions the 2 support points (23) in the groove bottoms directly adjacent to the shoulder block (1), and notes the first remaining height value indicated by the depth gauge (25). To carry out a second measurement in a second area of the shoulder block, the distance Dr2 and the angle Ar2 defined in the database are adjusted.Then, the maintenance professional positions the 2 support points (23) in the groove bottoms directly adjacent to the shoulder block (1), and notes the second remaining height value indicated on the depth gauge (25). From these two measurement points, two wear rates Txl and Tx2 are determined which are compared to thresholds accessible by the database. Following these measurements, a history is created, it includes the type of tire 46 17 R20, its individual identifier and the two wear rates Txl and Tx2 obtained from the measurements. If one of the thresholds is crossed, then the maintenance professional changes the tire. This check is repeated at regular intervals once a month and each time feeds the history linked to the tire checked. All the histories of the FA320 tires constitute a knowledge base, a source of information. for the optimization of thresholds and database wear laws.

[0046] In a second embodiment, the tire maintenance professional uses a portable digital tool to perform a wear check on the shoulder blocks of the tires of an A320 aircraft. The aircraft is equipped with Michelin tires of size 46 17 R20 where the information necessary for implementing the method is available in a mobile application accessing a remote database. The portable digital tool is locally georeferenced, and is equipped with a three-dimensional infrared image sensor. Local georeferencing means the operation which consists of quantifying relative displacements in the three spatial directions. The professional has chosen in this case the RealSense D415 camera (registered trademark) or the integrated digital camera of a mobile phone, making it possible to combine local geolocation and the capture of three-dimensional images. The camera communicates with an application installed on the mobile phone.Once the tire type is entered in the application, the first step of the measurement method is to move the camera near the tread to capture at least 30 images in the case of using the mobile phone camera, in different directions or a single image in the case of using the RealSense D145 camera (registered trademark). The application extracts a profile of the tread surface in a meridian plane of the 46 17 R20 tire from the series of images captured by the digital tool such as a mobile phone with a digital camera. With the use of the data contained in the database, a geometric calculation of points A, B, RI and II or even R2 and 12 is carried out by the application. The application determines the two respective wear rates Txl and Tx2 then checks whether the thresholds in the database are crossed.A history that includes the tire type 46 17 R20 and its individual identifier is completed with the two wear rates Txl and Tx2 obtained from the measurements. If one of the thresholds is crossed, then the maintenance professional changes the tire. This check is repeated at regular intervals once a month and feeds the history each time. Finally, all the A320 tire histories constitute a knowledge base, a source of information for optimizing the thresholds and wear laws of the database for all users of the application.

Claims

Claims

1. Method for measuring shoulder wear of a tire: The tire comprising a tread (2) comprising a tread surface (3) intended to come into contact with the ground, The tread (2) comprising at least one substantially continuous shoulder block (1) and at least two substantially circumferential grooves (6), The method using a database associating tire types and geometric data of these tires, at least one measuring tool and comprising the following steps: - Identification with a measuring tool of a first point A located in the groove (6) directly adjacent to the shoulder block (1), substantially continuous, said first point being the most radially inner point of said groove (6), - Identification with a measuring tool of a second point B located in the groove (6) directly adjacent to the groove (6) directly adjacent to the shoulder block (1), substantially continuous,said second point being the most radially inner point of said groove (6) and positioned in the same meridian plane as the first point A, - The type of tire is identified, - The database associates with the type of tire a distance making it possible to position a third point RI on the line (A, B) joining the first two points, RI being axially outside the first point A, - A measuring tool allows the identification on the tire of a fourth point II positioned in the same meridian plane as the first point A, said point being a projection of the third point RI onto the rolling surface (3) of the tire, - Determination of the distance Dl, called the first threshold distance, between the third point RI and the fourth point IL,

2. Method for measuring the shoulder wear of a tire according to claim 1 in which the fourth point II is the radial projection, in the meridian plane of the point 1, of the third point RI on the surface of rolling (3) of the tire.

3. Method for measuring the wear of a tire according to claim 1 to 2 in which: - The database associates with the type of tire a second distance and an angle DA making it possible to position a fifth point R2 on the straight line, called the second straight line, passing through the third point RI and making an angle equal to DA with the straight line (A, B), R2 is positioned in the same meridian plane as the point A, axially outside and radially inside RI, - A maintenance tool allows the identification on the tire of a distance, in the meridian plane comprising the first point A, said distance D2 is the distance from the fifth point R2 to the rolling surface (3).

4. Method for measuring the wear of a tire according to claims 1 to 3 in which the measuring tool makes it possible to record a profile of the rolling surface (3), in the meridian plane, including the profile of the two grooves (6) directly adjacent to the shoulder block (1), substantially continuous.

5. Method for measuring the wear of a tire according to claims 1 to 4, using a calculator in which: - The database associates with the type of tire a first reference distance Refll of the new profile (8) of the tire, relative to the third point RI, - The first wear rate Txl is calculated as being the ratio between the distance DI and the first reference distance Refll which is subtracted from 1.

6. Method for measuring the wear of a tire according to claims 3 to 5 in which: - The database associates with the type of tire a second reference distance RefI2 of the new profile (8) of the tire, relative to the fifth point R2, - A second wear rate Tx2 is calculated as being the ratio between the distance D2 and the second reference distance RefI2 which is subtracted from 1,

7. Method for measuring the wear of a tire having a substantially continuous block at each shoulder according to claims 1 to 5 in which said method is applied to one then the other shoulder block (1).

8. Maintenance method using the measurement method according to claims 1 to 7 in which: - The database associates a maintenance trigger threshold with the tire type, - A dismantling operation is triggered if the distance DI is less than the maintenance trigger threshold.

9. Maintenance method according to claim 8 in which: - The database associates a second maintenance trigger threshold with the tire type, - A dismantling operation is triggered if the distance D2 is less than the second maintenance trigger threshold.

10. Maintenance method according to claim 8 or 9 in which: - The database associates a wear rate with the type of tire, - A predictive maintenance date is proposed calculated from the wear rate and at least one wear rate Txl or Tx2.

11. Maintenance method according to claim 8 to 10 in which: - The tire is individually identified - A maintenance event is stored in a database which associates with the individual identification of the tire, at least one wear rate Txl or Tx2, or at least one of the distances to the surface DI or D2, - After at least two measurement events, a computer proposes a preventive maintenance date or an immediate maintenance operation.

12. A method of maintaining a tire according to any one of claims 8 to 11 for an aircraft tire.

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