CN108430807B

CN108430807B - Pneumatic tire comprising radial ply or bias ply carcass with large diameter cords

Info

Publication number: CN108430807B
Application number: CN201680068864.4A
Authority: CN
Inventors: H·费里戈; O·穆尔霍夫
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2015-12-19
Filing date: 2016-12-15
Publication date: 2020-05-19
Anticipated expiration: 2036-12-15
Also published as: CN108430807A; FR3045496B1; WO2017103834A1; FR3045496A1

Abstract

A pneumatic tire for a rolling assembly, the pneumatic tire comprising: at least one carcass reinforcement (2), the carcass reinforcement (2) being provided with cords (11); a tread (4), the tread (4) being connected to two beads (5) by two sidewalls (6), the beads (5) being contactable with a rim (7), the rim (7) having a rim flange top (7 b); each bead (5) comprising at least one circumferential reinforcing element; the sidewalls (6) having on their outer surface a series of alternating protrusions (8) and recesses (9), each protrusion (8) being provided on the surface of a sidewall (6); said projections (8) being arranged in a continuous manner at regular or irregular intervals between point a and point E; the cords of the carcass reinforcement have a diameter greater than 1mm or the cords of the carcass reinforcement are hybrid cords.

Description

Pneumatic tire comprising radial ply or bias ply carcass with large diameter cords

Technical Field

The present invention relates to a bias ply tire or a radial carcass tire.

Background

Radial carcass tires have been increasingly used in various markets, particularly in passenger vehicle tires. This success is due in particular to the properties of durability, comfort and low rolling resistance provided by radial tires.

The main parts of the tire are the tread, sidewalls and beads. The beads are intended to be in contact with the rim. In a radial tire, each of the main portions (i.e., the tread, sidewalls, and beads) constituting the tire has a function that is significantly different from each other, and thus has a well-known specific composition.

A radial tire is substantially reinforced by a carcass reinforcement comprising at least one carcass ply disposed at an angle substantially equal to 90 ° with respect to the circumferential direction of the tire. This carcass reinforcement is covered radially on the outside and under the tread by reinforcing plies, which form the belt.

Bias ply tires differ from radial tires in that there are at least two bias carcass plies disposed at an angle unequal to 90 ° with respect to the circumferential direction of the tire. Plies are referred to as "bias" because the angle of one ply to the next has the opposite sign.

Recall that according to the invention, the circumferential direction of the tyre is the direction in a plane perpendicular to the rotation axis of the tyre and tangential to the belt reinforcement of the tyre.

After the appearance of radial carcass tires, some bias ply tires are also provided with belt reinforcement beneath the tread.

In both types of tyre, the tread in direct contact with the ground has in particular the function of providing contact with the road and of needing to adapt to the shape of the ground. The sidewalls themselves absorb the unevenness of the ground while transmitting the mechanical forces required to support the vehicle load and allow its movement.

Belt reinforcements are reinforcements that on the one hand need to be sufficiently rigid for the edge deformation so that the tire can have the cornering or drift thrust required for turning and transmit the torque for traction or for braking, and on the other hand need to be extremely flexible in bending, i.e. to allow the curvature of its plane to vary so as to provide a sufficient contact area of the tire with the ground.

Therefore, the belt reinforcement generally has a composite structure that allows providing the required stiffness for a relatively low weight. The belt reinforcement is usually composed of at least two plies disposed at different angles, said plies comprising rubber-covered reinforcements in the form of cords. The reinforcing elements cross from one ply to the other with respect to the circumferential direction and may be symmetrical or asymmetrical with respect to this direction.

A tire comprising a sidewall with an external reinforcement intended to reduce the internal temperature at the location of the tire where damage may occur with use is known from document JP 2008068716A. However, in the case of a side impact (such as by a curb or pothole), the placement of these reinforcements on the sidewall may not properly reinforce the tire sidewall. In particular, with conventional tire designs, such impacts generated at various speeds and/or various impact angles can cause damage, sometimes even further causing tire scrap.

Furthermore, the current trend is to use rims made of aluminum (instead of steel) to contribute particularly to the overall aesthetic appearance of the vehicle, with the result that when the tyre is subjected to a side impact, it causes the constituent parts of the carcass to break upwards at a significantly lower rate. Furthermore, it is currently desirable to use tires with shorter and shorter sidewall heights, another consequence of which is the fact that: the impact on the sidewalls causes more severe damage than if the sidewalls were taller, and therefore more damage to the tire.

Also known by document JP 2003237317 is a tyre comprising discontinuous elastomeric rubber portions having different rigidity and provided on the sidewalls so as to reduce the noise inherent to the operation of the tyre.

Patent FR 888453 also describes a tyre casing, the two sides of which comprise projections made of elastomeric rubber intended, due to the geometry they have, to verify the pressure and load consistency of the tyre.

Finally, document US 2354715 discloses the presence of a protrusion of elastomeric rubber, comprising a metal element and arranged at the end of the tread of the tire and intended to avoid the tread from slipping during running.

Furthermore, in the event of impact by curbs or potholes, the tire may be damaged, for example, by becoming caught between the rim and an obstacle. As a result of the impact, the reinforcement elements of the tire sidewall may be damaged. The tire may locally deform and/or lose its inflation pressure. Many known solutions are able to reduce these risks. For example, the breaking force of the cords of the carcass reinforcement is increased according to one of the following methods:

increasing the breaking stress of the material (example: aramid or aramid/nylon or aramid/PET type hybrid cords);

increasing the cross section of the reinforcement (example: large diameter cords);

increasing the number of layers of reinforcement (typically a double-ply solution).

The increase in cord breaking force, either by increasing the cord diameter or by increasing the breaking stress of the material, is typically achieved as a total breaking force equal to the ply. This results in a more spaced cord. This causes visual defects in the tire sidewall, typically in the form of undulations or undulations.

In the case of alternating cords with different rigidities (in particular PET cords and nylon cords or nylon cords and aramid cords or aramid/nylon or aramid/PET type hybrid cords, etc.), visual defects may occur, revealing the cord geometry at the outer surface of the sidewall.

Increasing the sidewall thickness or decreasing the pitch between the reinforcement cords can limit the surface deformation of the tire sidewall. These solutions are costly and not conducive to performance due to the use of more material than is required for the tire to function properly.

Thus, there remains a need to be able to further improve the robustness of a tire sidewall against side impact without changing the current dimensions of the tire.

Disclosure of Invention

To this end, the invention provides a tire for a rolling assembly comprising a rim and a tire, the tire having at least one carcass reinforcement provided with cords and radially externally surmounted by a crown reinforcement, the crown reinforcement itself being radially internal to a tread having two axially outermost ends, the crown reinforcement consisting of at least one layer of reinforcing elements, the tread being connected to two beads by two sidewalls, the beads being intended to be in contact with the rim, the rim having a rim flange top, each bead having at least one circumferential reinforcing element, the sidewalls having on their outer surface a set of protrusions alternating with voids, each protrusion being provided on the surface of a sidewall, the protrusions being provided regularly or irregularly and continuously between points A and E,

-said point a is located at the position where the radially outer surface of the tread and the sidewalls intersect, having a radial axis ZZ' at a distance of length L from the equatorial plane AA_ASaid length L_ABetween 1/2(L-60mm) and 1/2(L-10mm), L being the nominal cross-sectional width, and

the point E is set at a radius as required such that:

o R₂<E<(0.75R₁+0.25R₂)，R₂is the radius at the top of the rim flange and R₁Is the radius of the nominal cross-sectional width (range I), or

o 0.95R₁<E<(0.75R_A+0.25R₁)，R₁Is the radius of the nominal cross-sectional width and R_AIs the radius at point a (range II),

and is

-the diameter of the cords of the carcass reinforcement is greater than 0.9 mm; or

-the cords of the carcass reinforcement are hybrid cords.

The large cords considered herein are cords having a diameter greater than 0.9mm, more preferably greater than 1 mm. This design can minimize the influence on the deformation of the sidewall surface due to the use of the carcass cord having a large diameter. The double advantage thus obtained is that on the one hand the rigidity of the reinforcement of the carcass reinforcement is increased and the robustness of the tire with respect to impacts is increased, and on the other hand the visual appearance of the sidewalls is optimized due to the presence of the protrusions. Finally, these advantages are obtained without any negative impact on other performance factors (e.g. rolling resistance). When the protrusions partially interrupt the grooves, this interruption occurs between 2 and 97%, preferably between 20 and 80%, more preferably between 30 and 50% of the total axial spacing of said grooves.

The trench is an area of a given width located near point a and has a longitudinal void ratio greater than 70%.

R₁Can be in (0.8R)₂+0.2R_A) And(0.2R₂+0.8R_A) Within the range of (a).

The advantage of the tyre according to the invention is that it can be produced quickly and easily and can withstand particularly severe side impacts without substantial damage that may pose a significant risk to the occupants of the vehicle. The tire according to the invention also has the advantage of providing an overall performance factor, such as rolling resistance, wear, durability, similar to a tire without protrusions on the sidewalls.

Advantageously, the tread comprises a circumferential groove at least one axially outermost end.

According to a first variant, at least one projection partially or completely interrupts the circumferential groove. According to another variant, each projection is adjacent to the circumferential groove. According to another variant, at least two adjacent or non-adjacent projections project into the circumferential groove.

Advantageously, said hybrid cords of said carcass reinforcement are made of aramid/nylon or aramid/PET.

Preferably, the height at the center of the protrusion is defined as follows:

i) point EQ is the axially outermost point of the tire sidewall;

ii) the point EQ is disposed at a distance REQ from the axis of rotation;

iii) the height of the protrusion at point EQ is less than the height at points at distances REQ +10mm and REQ-10mm relative to the axis of rotation.

Preferably, the at least two projections have different lengths from each other. Preferably, the average height of each protrusion is between 3 and 10mm, more preferably between 5 and 8 mm.

The height of the protrusion may be variable. The maximum height of the protrusion is between 3 and 10 mm. The minimum height may be close to 0. More preferably, the maximum height of the protrusion is between 4 and 8 mm. Preferably, the average width of each projection is between 4 and 12 mm.

The average height of the protrusions may be greater than 80% of the maximum height over at least 80% of the distance between points a and E. The average height is defined as the average of the heights between the ends of the projections.

the projection preferably has α lift-off angle α of less than or equal to 20 °, more preferably between 5 and 8 °.

Two adjacent projections may be spaced apart from each other by an average distance that is less than or equal to 2 times the average width of the projections, and may be substantially parallel to each other.

The protrusions preferably cover at least 40% of the total circumferential surface of the sidewall between points a and E.

each protrusion, of determined or arbitrary geometry, may have a neutral fibre passing through the radially innermost end and the radially outermost end and disposed at an angle β between-60 ° and +60 ° with respect to the radial direction ZZ'.

The outer sidewall of the tire (the sidewall that is on the outside when mounted on a vehicle) and the inner sidewall of the tire (the sidewall that is on the inside when mounted on a vehicle) may each include a protrusion having any possible combination of inclinations. Likewise, the four tires of the vehicle may have inclinations that may vary according to each axle and/or may vary on the same axle.

Preferably, the void between two adjacent projections continues the void of the circumferential groove of the tread extending axially through point a, said groove being provided at least one axial end of the tread.

Preferably, in the sidewall region close to point a (i.e. arranged between 3 and 8 mm), the gap between two adjacent projections is arranged at an angle of between-15 ° and +15 ° with respect to the circumferential direction.

The tire according to the invention has a [ over radius R ]₁The total sum of the total width of each projection in the circumferential direction of]A ratio of/2 π R greater than or equal to 30%, more preferably equal to 60%, the width of each projection being defined at 50% of the total height of said projection, and any radius R of the tire being at R_E<R<R_aIn which R is_aIs the radius at point A and R_EIs the radius at point E.

There may be a protrusion along the entire circumferential length of the tire sidewall. Advantageously, the protrusions present on the sidewalls are made of the same material as the sidewalls.

The invention also provides a mounting assembly comprising a rim and a tire as described above.

Drawings

The invention will now be described by means of the following examples and the accompanying drawings, which are for illustration only and in which:

figure 1 schematically shows a cross section of a tyre according to the invention in a radial plane.

Figures 2A and 2B are three-dimensional schematic views of a portion of a sidewall and of a corresponding tread of a tyre according to the invention,

figure 3 schematically shows an enlarged portion of a sidewall comprising a protrusion of a tyre according to the invention,

figure 4 shows a cross-section along line AA of figure 3 of two adjacent lugs of a tyre according to the invention,

figures 5A and 5B show, in a first variant, in three dimensions, a portion of the radially external portion of the sidewalls and of the corresponding tread of a tyre according to the invention,

figure 6A shows, in a second variant form, in three dimensions, a portion of the radially outer portion of the sidewall and of the corresponding tread of a tyre according to the invention, in which some of the protrusions completely interrupt the circumferential groove,

figure 6B shows, in another variant, in three dimensions, a portion of the radially outer portion of the sidewall and of the corresponding tread of a tyre according to the invention, in which some of the projections partially interrupt the circumferential groove,

figure 7A shows a partial view in radial section of a portion of a sidewall and of a portion of the corresponding tread according to another variant,

figure 7B shows a partial view in radial section of a portion of a sidewall and of a portion of the corresponding tread according to another variant of the tyre according to the invention,

figures 8A and 8B schematically show different layers of a tyre with large cords or hybrid cords in the absence of protrusions (figure 8A) and in the presence of protrusions (figure 8B),

the table shown in fig. 9 presents in detail the variation in thickness of the cord diameter with respect to the sidewall thickness.

In the respective figures, identical or similar technical elements have identical reference numerals. Their description need not be repeated in order not to unduly recite them.

Detailed Description

Definition of

The following definitions are used herein:

"longitudinal or circumferential direction" is the direction of travel of the tyre,

"radial direction" is the direction intersecting the axis of rotation of the tyre and perpendicular thereto,

"axial direction" is a direction parallel to the axis of rotation of the tyre,

"radially on the inside" means closer to the axis of rotation of the tyre,

"radially on the outside" means further away from the axis of rotation,

"equatorial plane or median plane" means a plane perpendicular to the axis of rotation of the tyre and dividing the tyre into two substantially equal halves,

"transverse direction of the tyre" means a direction parallel to the axis of rotation,

"radial or meridian plane" means a plane containing the axis of rotation of the tyre.

The expression "partially interrupted" means that the radially upper end of the projection partly intersects the circumferential groove.

The expression "completely interrupted" means that the radially upper end of the projection intersects the axially outer end of the tread closest to said radially upper end.

The term "law" defines the fact that: the projections disposed between points a-E are uniformly disposed in vertical alignment (possibly with symmetry) in the radial direction.

The fact that the term "irregular" is defined is: the projections disposed between the points a-E are deviated (without symmetry) in both the radial direction and the parallel direction and are disposed unevenly.

Radius R_AIs a width L_AOf said width L, said width L_AItself as a function of the width L.

The nominal section width L is defined as the section width of the tire mounted on the rim and inflated; according to the present invention, the cross-sectional width is the distance between the outer sides of the sidewalls of the pneumatic tire, including the sidewall surface relief. R₁Corresponding to the radius at a point on the outer surface of the sidewall furthest from the median plane. The definition of the section width according to the invention applies to any type of casing combined with any type of rim.

REQ is the radius at the widest point of the tire (width ═ L): preferably, R is_A>REQ。

As shown in fig. 1, the passenger vehicle tyre of reference numeral 1 comprises a carcass reinforcement 2, said carcass reinforcement 2 being radially internal to a belt reinforcement 3, said belt reinforcement 3 being radially internal to a tread 4, said tread 4 itself being connected to two beads 5 by two sidewalls 6. The beads 5 are intended to be in contact with a rim 7 (partially shown). Each bead comprises at least one circumferential reinforcing element 7 a. On the surface of the sidewall, the latter has a set of protrusions 8, said protrusions 8 regularly alternating with voids 9 (shown in figure 2). Fig. 1 shows in cross section a protrusion 8 with continuous neutral fibers. It should be recalled here that a neutral fiber is the name given to a neutral axis which passes substantially through the centre of volume of each projection and is neither shortened nor lengthened when subjected to compression and/or denting.

As shown in fig. 1, the protrusions 8 are disposed on the surface of the sidewall along a continuous length of neutral fiber extending from point a to point E.

Point E can be set according to two methods (herein labeled as range I and range II).

o in range I, the radius at point E is: r₂<E<(0.75R₁+0.25R₂)，R₂Is the radius of the rim flange top 7b and R₁A radius of a nominal cross-sectional width.

o is in the range II, pointThe radius at E is: 0.95R₁<E<(0.75R_A+0.25R₁)，R₁Is the radius of the nominal cross-sectional width and R_AIs the radius at point a.

According to one embodiment, for a 205/55R 16 reference tire mounted on a 6.5J 16 rim, point E is set at a location with a radius of 232mm, where R is_AEqual to 298mm, R₂Equal to 220mm and R₁Equal to 261 mm.

Said point A being arranged at the location where the radially outer surface of the tread and the sidewalls intersect and having a radial axis ZZ' at a distance of length L from the equatorial plane AA_ASaid length L_ABetween 1/2(L-60mm) and 1/2(L-10mm), L being the nominal cross-sectional width. For the 205/55R 16 reference tire, R_AEqual to 298 mm.

The projections are not insert rubber elements that are incorporated into the sidewall rubber, but are molded during the curing stage. The protrusions are obtained in a similar manner to the tread pattern formed on the tread.

Fig. 2A shows the alternation of projections 8 and voids 9, shown in an enlarged form in fig. 3 and 4. Fig. 2B shows a variant of fig. 2A, in which the projections are arranged at an angle with respect to the axial direction. In this embodiment, the longest continuous protrusion 8 has a neutral fiber length of about 75mm for a 205/55R 16 size tire. The projections are arranged radially (fig. 2) substantially parallel to each other and are spaced apart from each other by about 4.50mm, having a height of about 6mm and a width of about 8.6mm at the axially innermost portion thereof.

the relief angle α is about 8 deg., as shown in fig. 4, the value of which allows the tire to be demolded after curing without destroying the final structure according to this embodiment, the lugs have at mid-height [ beyond the radius R ]₁The sum of the widths of each of the protrusions in the circumferential direction of]The ratio/2 π R is equal to 30% and is arranged at an angle of zero degrees with respect to the radial plane.

Fig. 5A shows a three-dimensional view of the radially outer portion 8a of the projection 8, and fig. 5B is an enlarged view of fig. 5A. In fig. 5A and 5B, the portion 8a and the void 9 of each protrusion 8 are adjacent to a groove 10 provided in the circumferential direction on the surface at the axially outermost end 4a of the tread 4. The length of the groove 10 is uninterrupted. In this particular embodiment, the groove 10 has an axial width "l" along the axis YY 'which may be between 2 and 10mm and a radial height "h" along the axis ZZ' which is between 3 and 8 mm.

Fig. 6A also shows a three-dimensional view of the radially outer portion 8a of the projection 8. Unlike fig. 5A and 5B, the trench 10 is interrupted. In particular, the end 8a of the protrusion 8 and the adjacent void 9 completely intersect the groove 10 in the tire circumferential direction. Fig. 6B shows another variant of a three-dimensional view of said radially outer portion 8a of the projection 8. In the figure, the protrusion 8 partially intersects the groove 10 in the tire circumferential direction.

Fig. 7A and 7B show radially inner portion 8B (shown in phantom) of projection 8 spaced from radially inner portion 10B of groove 10 by a thickness "d". The thickness "d" is less than 2mm and preferably less than 1 mm.

Fig. 8A and 8B show in particular an embodiment of the weld of the carcass reinforcement. In these embodiments, the cords have a diameter greater than 0.9 mm. Fig. 8A clearly shows the deformation causing the undulation phenomenon leading to the appearance defect. In this case, the excessive thickness caused by the large diameter cords is about 800 microns. A concave or undulating appearance is visible on the sidewall. The dimples vary with cord diameter and sidewall thickness. Fig. 8B shows a recommended scheme that can alleviate the visual effect, and thus can eliminate the appearance defect.

The graph of fig. 9 shows the effect of cord diameter and sidewall thickness on the degree of sidewall deformation for sidewall thicknesses of 3 and 5 mm. The curves of the squares and diamonds relate to conventional designs. When large cord diameters are used, it is clear that the degree of deformation reaches large values. The boxed areas represent configurations where the apparent defects significantly exceed the allowable threshold. It is evident that the curves indicated by crosses corresponding to the tyres according to the invention provide particularly advantageous effects, with a significantly reduced degree of deformation compared to conventional arrangements.

Advantageously, the minimum distance between the outer surface and the cord is 3.1 mm. The minimum protrusion height is about 3 mm.

Hybrid reinforcements are textile reinforcements that include a combination of at least two different textile materials. For example, the hybrid reinforcement a 167/N140280/280 consists of three strands, two of which are made of 167tex aramid and the other of 140tex nylon and a twist of 280 turns per meter (tpm). The three strands were twisted together with a balanced twist of 280 tpm.

The following are some examples of hybrid cords:

A330/A330/N188 230/230

A167/A167/N140 280/280

A167/N140 290/290

J220/2 240/240

J334/2 270/270

thus, the invention is able to combine solutions corresponding to: increasing the cord stiffness by increasing the cross section of the reinforcement (example: large diameter cord); or by using multi-material cords (in particular hybrid cords of aramid/nylon or aramid/PET type) in order to increase the cord stiffness.

By providing a set of protrusions and voids on the tire sidewall, the effect of the undulations of the sidewall is limited.

The tire according to the invention is obtained in a conventional manner after curing and moulding in a curing mould.

Reference numerals used in the drawings

1 tire

2 carcass reinforcement

3 Belt Reinforcement

4 Tread

4a axially outermost end of tread

5 tyre bead

6 side wall

7 wheel rim

7a circumferential reinforcing element

7b rim flange top

8 projection

8a end of the projection

Radially inner part of the 8b, 8c, 8d projection

9 gap

10 circumferential grooves

10b radial inner part of groove

11 large diameter cords or hybrid cords.

Claims

1. Tyre for a rolling assembly comprising a rim and a tyre, the tyre having at least one carcass reinforcement (2), the carcass reinforcement (2) being provided with cords (11) and being radially external surmounted by a crown reinforcement (3), the crown reinforcement (3) itself being radially internal to a tread (4), the tread (4) having two axially outermost ends, the crown reinforcement (3) being composed of at least one layer of reinforcing elements, the tread (4) being connected to two beads (5) by two sidewalls (6), the beads (5) being intended to be in contact with a rim (7), the rim (7) having a rim flange top (7b), each bead (5) having at least one circumferential reinforcing element, the sidewalls (6) having on their external surface a set of protrusions (8), the protrusions (8) alternating with voids (9), characterized in that each protrusion (8) is provided on the surface of a sidewall (6), said protrusions (8) being regularly or irregularly and continuously provided between a point A and a point E,

-said point a is located at the position where the radially outer surface of the tread and the sidewalls intersect, has a radial axis ZZ 'at a distance from the equatorial plane AA' of a length LA between (L-60mm)/2 and (L-10mm)/2, L being the nominal section width, defined as the section width of the tyre mounted on the rim and inflated, and

the point E is set at a radius as required such that:

o R₂<E<(0.75R₁+0.25R₂)，R₂is the radius at the top of the rim flange and R₁Is the radius of the nominal cross-sectional width, or

o 0.95R₁<E<(0.75R_A+0.25R₁)，R₁Is the radius of the nominal cross-sectional width and R_AIs the radius at the point a and,

and:

-the cords of the carcass reinforcement are hybrid cords.

2. Tyre according to claim 1, wherein the tread (4) comprises a circumferential groove (10) at least one axially outermost end (4 a).

3. Tyre according to claim 2, characterized in that at least one protrusion (8) partially or completely interrupts the circumferential groove (10).

4. Tyre according to claim 2, characterized in that each protrusion is adjacent to the circumferential groove (10).

5. Tyre according to claim 2, characterized in that at least two adjacent or non-adjacent protrusions project into said circumferential groove (10).

6. Tyre according to any one of the preceding claims, characterized in that said hybrid cords of said carcass reinforcement are made of aramid/nylon or aramid/PET.

7. Tyre according to any one of claims 1 to 5, characterized in that the height at the centre of the projection is defined as follows:

i) point EQ is the axially outermost point of the tire sidewall;

ii) the point EQ is disposed at a distance REQ from the axis of rotation;

8. Tyre according to any one of claims 1 to 5, characterized in that at least two projections (8) have different lengths from each other.

9. Tyre according to any one of claims 1 to 5, characterized in that the average height of each protrusion (8) is between 3 and 10 mm.

10. Tyre according to any one of claims 1 to 5, characterized in that the average width of each protrusion (8) is between 4 and 12 mm.

11. Tyre according to any one of claims 1 to 5, characterized in that the average height of each projection (8) is greater than 80% of the maximum height over at least 80% of the distance between points A and E.

12. Tyre according to any one of claims 1 to 5, characterized in that two adjacent lugs (8) are spaced from each other by an average distance less than or equal to 2 times the average width of the lugs.

13. Tyre according to any one of claims 1 to 5, characterized in that two adjacent lugs (8) are substantially parallel to each other.

14. Tyre according to any one of claims 1 to 5, characterized in that said protrusions (8) cover at least 40% of the total circumferential surface of said sidewalls between points A and E.

15. Tyre according to any one of claims 1 to 5, characterized in that the void (9) between two adjacent protrusions (8) continues the void of a circumferential groove of the tread extending axially through the point A, the groove being provided at least one axial end of the tread.

16. Tyre according to any one of claims 1 to 5, characterized in that in the sidewall region close to said point A, two adjacent protrusions (8) form a gap therebetween, said gap being disposed at an angle of between-15 ° and +15 ° with respect to the circumferential direction.

17. Tyre according to any one of claims 1 to 5, characterized in that said tyre toolSome [ total sum of total width of each protrusion in circumferential direction across radius R1]A ratio of/2 π R greater than or equal to 30% and less than or equal to 70%, the width of each projection (8) being defined at 50% of the total height of said projection (8), and the radius R of the tire being at R_E<R<R_AIn which R is_AIs the radius at point A and R_EIs the radius at point E.

18. A mounting assembly comprising a rim and a tyre according to any one of the preceding claims.