MINI RIM TIRE

Abstract

The tire (11) for a passenger vehicle comprises an axially narrowest working layer (26), the axially narrowest working layer (26) having an axial width T2 expressed in mm. The tire is adapted to be mounted (10) on a mounting support (100) comprising a rim (200) having a rim width A expressed in mm and a rim width code according to the ETRTO 2019 Standards Manual. The tire (11) has a load index L1 such that LI≥LI′+1, LI′ being the load index of an EXTRA LOAD tire of the same size according to the ETRTO 2019 Standards Manual. The ratio T2/A is such that T2/A≤1.00. The rim width code is equal to the measuring rim width code for the tire size minus 0.5.

Claims

1.-13. (canceled)

14. A tire (11) for a passenger vehicle comprising a crown (12), two beads (32), two sidewalls (30) each connecting each bead (32) to the crown (12), and a carcass reinforcement (34) anchored in each bead (32), the crown (12) comprising a crown reinforcement (16) and a tread (14), the carcass reinforcement (34) extending in each sidewall (30) and in the crown (12) radially internally to the crown reinforcement (16), the crown reinforcement (16) being arranged radially between the tread (14) and the carcass reinforcement (34) and comprising a working reinforcement (20) comprising at least an axially narrowest working layer (26), the axially narrowest working layer (26) having an axial width T2 expressed in mm, the tire (11) being adapted to be mounted on a mounting support (100) comprising a rim (200), wherein the tire (11) has a load index L1 such that LI≥LI′+1, with LI′ being a load index of an EXTRA LOAD tire of a same size according to standard ETRTO 2019, and wherein, when the tire is mounted on a rim having a rim width code equal to a measuring rim width code for a tire size defined according to standard ETRTO 2019 minus 0.5, a ratio T2/A is such that T2/A≤1.00 with A being a rim width A according to standard ETRTO 2019, expressed in mm of the rim.

15. The tire according to claim 14, wherein LI′+1≤LI≤LI′+4.

16. The tire according to claim 14, wherein 0.85≤T2/A.

17. The tire according to claim 14, wherein the tire (11) has a nominal section width SW such that T2≥SW−75 and T2≤SW−27.

18. The tire according to claim 14, wherein the tire (11) has a nominal section width SW ranging from 205 to 315, a nominal aspect ratio ranging from 25 to 55, a nominal rim diameter ranging from 17 to 23 and the load index LI ranging from 98 to 116.

19. The tire according to claim 14, wherein 0.82≤H/LI≤0.98, H being a sidewall height defined by H=SW×AR/100, where SW is a nominal section width and AR is a nominal aspect ratio of the tire.

20. The tire according to claim 14, wherein the tire (11) has a size and the load index LI selected from the following sizes and load indexes: 225/55R18 105, 225/55ZR18 105, 205/55R19 100, 205/55ZR19 100, 235/45R21 104, 235/45ZR21 104, 285/45R22 116, 285/45ZR22 116, 205/40R17 88, 205/40ZR17 88, 245/40R19 101, 245/40ZR19 101, 255/40R20 104, 255/40ZR20 104, 245/40R21 103, 245/40ZR21 103, 255/40R21 105, 255/40ZR21 105, 265/40R21 108, 265/40ZR21 108, 255/40R22 106, 255/40ZR22 106, 255/35R18 98, 255/35ZR18 98, 245/35R20 98, 245/35ZR20 98, 265/35R20 102, 265/35ZR20 102, 245/35R21 99, 245/35ZR21 99, 255/35R21 101, 255/35ZR21 101, 265/35R21 103, 265/35ZR21 103, 275/35R21 105, 275/35ZR21 105, 285/35R21 108, 285/35ZR21 108, 295/35R22 111, 295/35ZR22 111, 275/35R23 108, 275/35ZR23 108, 285/30R21 103, 285/30ZR21 103, 315/30R21 109, 315/30ZR21 109, 325/30R21 111, 325/30ZR21 111, 315/30R23 111, and 315/30ZR23 111.

21. The tire (11) according to claim 14, wherein the tire (11) is inflated to a pressure ranging from 200 to 350 kPa.

22. The tire (11) according to claim 14, wherein the working reinforcement (20) comprises a radially inner working layer (24) and a radially outer working layer (26) arranged radially on an outside of the radially inner working layer (24).

23. The tire (11) according to claim 14, wherein the axially narrowest working layer (26) or each working layer (24, 26) is delimited axially by two axial edges (241, 242, 261, 262) of the working layer (24, 26) and comprises working filamentary reinforcing elements extending axially from one axial edge to an other axial edge of the working layer (24, 26) substantially parallel to one another.

24. The tire (11) according to claim 23, wherein each working filamentary reinforcing element extends in a main direction forming an angle which, in terms of absolute value, is strictly greater than 10° with a circumferential direction (X) of the tire (11).

25. The tire (11) according to claim 14, wherein the carcass reinforcement (34) comprises at least one carcass layer (36, 37), the or each carcass layer (36, 37) being delimited axially by two axial edges (361, 362, 371, 372) of the or each carcass layer (36, 37) and comprises textile carcass filamentary reinforcing elements (360, 370) extending axially from one axial edge to an other axial edge of the or each carcass layer (36, 37) in a main direction forming an angle which, in terms of absolute value, ranges from 80° to 90°, with a circumferential direction (X) of the tire (11).

26. The tire (11) according to claim 14, wherein the carcass reinforcement comprises a single carcass layer, the tire having a sidewall height H defined by H=SW×AR/100 with SW being a nominal section width and AR a nominal aspect ratio of the tire and such that H<95 and that 0.82≤H/LI≤0.92.

27. The tire (11) according to claim 26, wherein the single carcass layer forms a winding around a circumferential reinforcing element of each bead such that an axially inner portion of the single carcass layer is arranged axially on an inside of an axially outer portion of the single carcass layer and such that each axial end of the single carcass layer is arranged radially on an outside of each circumferential reinforcing element.

28. The tire (11) according to claim 26, wherein the single carcass layer has a portion arranged axially between two circumferential reinforcing elements of each bead and each axial end of the single carcass layer is arranged radially on an inside of each radially outer end of each circumferential reinforcing element of each bead.

29. The tire (11) according to claim 14, wherein the carcass reinforcement comprises first and second carcass layers, the tire having a sidewall height H defined by H=SW×AR/100 with SW being a nominal section width and AR a nominal aspect ratio of the tire and such that H≥95 and that 0.88≤H/LI≤0.98.

30. The tire (11) according to claim 14, wherein the crown reinforcement (16) comprises a hoop reinforcement (22) delimited axially by two axial edges (281, 282) of the hoop reinforcement and comprising at least one hooping filamentary reinforcing element wound circumferentially in a helix so as to extend axially between the axial edges (281, 282) of the hoop reinforcement (22).

Description

[0109] The invention will be understood better on reading the following description, which is given purely by way of non-limiting example and with reference to the drawings, in which:

[0110] FIG. 1 is a view, in a meridian section plane, of a mounted assembly comprising a tyre according to a first embodiment of the invention,

[0111] FIG. 2 is a view, in a meridian section plane, of the tyre of FIG. 1,

[0112] FIG. 3 is a view in section on the plane III-III′ of FIG. 2 showing the carcass reinforcement of the tyre of FIG. 1,

[0113] FIGS. 4 and 5 are views similar to FIGS. 2 and 3, respectively, of a tyre according to a second embodiment, and

[0114] FIG. 6 is a view similar to that of FIG. 1 comparing the deflection of a mounted assembly of the prior art and the deflection of the mounted assembly of FIG. 1.

[0115] A frame of reference X, Y, Z corresponding to the usual axial (Y), radial (Z) and circumferential (X) directions, respectively, of a tyre or a mounted assembly is shown in the figures.

[0116] In the following description, the measurements taken are taken on an unladen and non-inflated tyre or on a section of a tyre in a meridian plane.

Tyre According to a First Embodiment

[0117] FIG. 1 shows a mounted assembly denoted by the general reference 10. The mounted assembly 10 comprises a tyre 11 according to the invention and a mounting support 100 comprising a rim 200. The tyre 11 is in this case inflated to a pressure ranging from 200 to 350 kPa, preferably from 250 to 330 kPa and in this case equal to 270 kPa.

[0118] The tyre 11 has a substantially toric shape about an axis of revolution R substantially parallel to the axial direction Y. The tyre 11 is intended for a passenger vehicle. In the various figures, the tyre 11 is depicted as new, which is to say when it has not yet been run.

[0119] The tyre 11 comprises two sidewalls 30 bearing a marking indicating the size of the tyre 11, as well as a speed index and a speed code. In the case at hand, the tyre 11 has a nominal section width SW ranging from 205 to 315, preferably from 225 to 315, more preferentially ranging from 245 to 315 and here equal to 205. The tyre 11 also has a nominal aspect ratio AR ranging from 25 to 55, preferably ranging from 30 to 45, and here equal to 40. The tyre 11 has a nominal rim diameter ranging from 17 to 23, and here equal to 17. The tyre 11 therefore has a sidewall height H defined by SW×AR/100=82<95.

[0120] In accordance with the invention, the marking also comprises a load index LI ranging from 98 to 116, such that LI≥LI′+1 with LI′ being the load index of an EXTRA LOAD tyre of the same size according to the ETRTO 2019 Standards Manual. Preferably, LI′+1≤LI≤LI′+4, and even LI′+2≤LI≤LI′+4.

[0121] A tyre of size 205/40R17 in its EXTRA LOAD version has a load index equal to 84 as indicated on page 34 of the part Passenger Car Tyres—Tyres with Metric Designation of the ETRTO 2019 Standards Manual. Thus, the load index LI of the tyre 11 is such that LI≥85, preferably 85≤LI≤88 and even 86≤LI≤88 and in this case LI=88. This load index equal to 88 corresponds to the load index of a HIGH LOAD CAPACITY tyre of size 205/40R17. Thus, the tyre 11 is indeed of the HIGH LOAD CAPACITY type.

[0122] The tyre 11 is such that 0.82≤H/LI≤0.98 and in this case H/LI=0.93.

[0123] For such a size, the ETRTO 2019 Standards Manual indicates, on page 34 of the part Passenger Car Tyres—Tyres with Metric Designation, a measuring rim with a rim width code equal to 7.5. The tyre is adapted to be mounted on the rim 200 of the mounted assembly 10.

[0124] In this case, the rim 200 is the rim having a rim width code equal to the measuring rim width code for the tyre size minus 0.5 and therefore here equal to 7.0. The rim 200 has a profile of type J and a rim width A according to the ETRTO 2019 Standards Manual. In the case at hand, the profile of the rim 200 being of type 7.0 J, its rim width A expressed in mm is equal to 177.80 mm.

[0125] With reference to FIG. 2, the tyre 11 comprises a crown 12 comprising a tread 14 intended to come into contact with the ground when it is running and a crown reinforcement 16 extending in the crown 12 in the circumferential direction X. The tyre 11 also comprises a layer 18 that is airtight with respect to an inflation gas and is intended to delimit an internal cavity closed with the mounting support 100 for the tyre 11 once the tyre 11 has been mounted on the mounting support 100.

[0126] The crown reinforcement 16 comprises a working reinforcement 20 and a hoop reinforcement 22. The working reinforcement 16 comprises at least one working layer and in this case comprises two working layers comprising a radially inner working layer 24 arranged radially on the inside of a radially outer working layer 26. Of the two radially inner 24 and radially outer 26 layers, the axially narrowest layer is the radially outer layer 26.

[0127] The hoop reinforcement 22 comprises at least one hooping layer and in this case comprises one hooping layer 28.

[0128] The crown reinforcement 16 is surmounted radially by the tread 14. In this case, the hoop reinforcement 22, in this case the hooping layer 28, is arranged radially on the outside of the working reinforcement 20 and is therefore interposed radially between the working reinforcement 20 and the tread 14.

[0129] The two sidewalls 30 extend the crown 12 radially inwards. The tyre 11 also has two beads 32 radially on the inside of the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown 12.

[0130] The tyre 11 comprises a carcass reinforcement 34 that is anchored in each bead 32 and, in this instance, forms a winding around a circumferential reinforcing element 33, in this case a bead wire. The carcass reinforcement 34 extends radially in each sidewall 30 and axially in the crown 12, radially on the inside of the crown reinforcement 16. The crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 comprises at least one carcass layer 36 and in this case a single carcass layer 36.

[0131] The hoop reinforcement 22, in this case the hooping layer 28, is delimited axially by two axial edges 281, 282 and comprises one or more hooping filamentary reinforcing elements that are wound circumferentially helically between each axial edge 281, 282 in a main direction forming an angle AF which, in terms of absolute value, is less than or equal to 10°, preferably less than or equal to 7° and more preferentially less than or equal to 5° with the circumferential direction X of the tyre 10. In this case, AF=−5°.

[0132] Each radially inner 24 and radially outer 26 working layer is delimited axially by two axial edges 241, 242, 261, 262, respectively, of each working layer 24, 26. The radially inner working layer 24 has an axial width T1=180.00 mm and the radially outer working layer 26 has an axial width T2=166.00 mm, making the radially outer working layer 26 the axially narrowest working layer.

[0133] Note that SW=205 and T2=166 satisfy the following relations T2≥SW−75, preferably T2≥SW−70 and T2≤SW−27, preferably T2≤SW−30.

[0134] As shown in FIG. 1, the tyre 11 has radially straightened sidewalls. To be specific, the ratio T2/A is such that 0.85≤T2/A≤1.00, preferably 0.90≤T2/A≤1.00, and more preferentially 0.93≤T2/A≤0.97 and in this case T2/A=0.93.

[0135] Each working layer 24, 26 comprises working filamentary reinforcing elements extending axially from one axial edge 241, 261 to the other axial edge 242, 262 of each working layer 24, 26 substantially parallel to one another in main directions forming oppositely oriented angles AT1 and AT2, respectively, which, in terms of absolute value, are strictly greater than 10°, preferably ranging from 15° to 50° and more preferentially ranging from 20° to 35° with the circumferential direction X of the tyre 10. In this case, AT1=−26° and AT2=+26°.

[0136] The single carcass layer 36 is delimited axially by two axial edges 361, 362, respectively, and comprises textile carcass filamentary reinforcing elements 360 extending axially from one axial edge 361 to the other axial edge 362 in a main direction D3 forming an angle AC which, in terms of absolute value, ranges from 80° to 90° with the circumferential direction X of the tyre 10; in this case AC=+90°.

[0137] The single carcass layer 36 forms a winding around each circumferential reinforcing element 33 of each bead 32 such that an axially inner portion 3611, 3621 of the first carcass layer 36 is arranged axially on the inside of an axially outer portion 3612, 3622 of the first carcass layer 36 and such that each axial end 361, 362 of the first carcass layer 36 is arranged radially on the outside of each circumferential reinforcing element 33.

[0138] Each axial end 361, 362 of the single carcass layer 36 is arranged radially on the inside of the equator E of the tyre. More specifically, each axial end 361, 362 of the first carcass layer 36 is arranged at a radial distance RNC of less than or equal to 30 mm from a radially outer end 331 of each circumferential reinforcing element 33 of each bead 32. In this case, RNC=23 mm.

[0139] Each working layer 24, 26, hooping layer 28 and carcass layer 36 comprises a matrix for calendering the filamentary reinforcing elements of the corresponding layer. Preferably, the calendering matrix is polymeric and more preferentially elastomeric like those usually used in the field of tyres.

[0140] Each hooping filamentary reinforcing element conventionally comprises two multifilament plies, each multifilament ply being made up of a spun yarn of aliphatic polyamide, in this instance nylon, monofilaments, with a count equal to 140 tex, these two multifilament plies being twisted in a helix individually at 250 turns per meter in one direction and then twisted together in a helix at 250 turns per meter in the opposite direction. These two multifilament plies are wound in a helix around one another. As an alternative, use could be made of a hooping filamentary reinforcing element comprising one multifilament ply made up of a spun yarn of aliphatic polyamide, in this case nylon, monofilaments with a count equal to 140 tex, and one multifilament ply made up of a spun yarn of aromatic polyamide, in this case aramid, monofilaments with a count equal to 167 tex, these two multifilament plies being twisted in a helix individually at 290 turns per meter in one direction and then twisted together in a helix at 290 turns per meter in the opposite direction. These two multifilament plies are wound in a helix around one another. As another alternative, use could be made of a hooping filamentary reinforcing element comprising two multifilament plies, each made up of a spun yarn of aromatic polyamide, in this case aramid, monofilaments with a count equal to 330 tex, and one multifilament ply made up of a spun yarn of aliphatic polyamide, in this case nylon, monofilaments with a count equal to 188 tex, each of the multifilament plies being twisted in a helix individually at 270 turns per meter in one direction and then twisted together in a helix at 270 turns per meter in the opposite direction. These three multifilament plies are wound in a helix around one another.

[0141] In general, the use of a heavy load leads to a reduction in the acceptable speed limit of the tyre as well as a deterioration in its behavior, for example its cornering stiffness. Thus, by using one or more high-modulus hooping filamentary reinforcing elements, for example like those described in the last two alternatives above comprising one or more aromatic polyamide plies, it is possible to increase the acceptable speed limit for the tyre and improve the behavior, in particular its cornering stiffness.

[0142] Each working filamentary reinforcing element is an assembly 4.26 of four steel monofilaments comprising an inner layer of two monofilaments and an outer layer of two monofilaments wound together in a helix around the inner layer at a pitch of 14.0 mm, for example in the direction S. Such an assembly 4.26 has a force at break equal to 640 N, a diameter equal to 0.7 mm. Each steel monofilament has a diameter equal to 0.26 mm and a mechanical strength equal to 3250 MPa. As an alternative, use could also be made of an assembly of six steel monofilaments having a diameter equal to 0.23 mm, comprising an inner layer of two monofilaments wound together in a helix at a pitch of 12.5 mm in a first direction, for example the direction Z, and an outer layer of four monofilaments wound together in a helix around the inner layer at a pitch of 12.5 mm in a second direction, opposite to the first direction, for example the direction S.

[0143] As shown in FIG. 3, each textile carcass filamentary reinforcing element 360 comprises an assembly of at least two multifilament plies 363, 364. Each multifilament ply 363, 364 is selected from a polyester multifilament ply, an aromatic polyamide multifilament ply and an aliphatic polyamide multifilament ply, preferably selected from a polyester multifilament ply and an aromatic polyamide multifilament ply. In the case at hand, the assembly is selected from an assembly of two polyester multifilament plies and an assembly of a polyester multifilament ply and an aromatic polyamide multifilament ply, and in this case is made up of two PET multifilament plies, these two multifilament plies being twisted in a helix individually at 270 turns per meter in one direction and then twisted together in a helix at 270 turns per meter in the opposite direction. Each of these multifilament plies has a count equal to 334 tex such that the total count of the assembly is greater than or equal to 475 tex and in this case equal to 668 tex. Each textile carcass filamentary reinforcing element 360 has an average diameter D, expressed in mm, such that D≥0.85 mm, preferably D≥0.90 mm and such that D≤1.10 mm, preferably D≤1.00 mm. In this case, D=0.95 mm.

Tyre According to a Second Embodiment

[0144] A tyre according to a second embodiment will now be described with reference to FIGS. 4 and 5. Elements similar to those of the first embodiment are denoted by identical references.

[0145] Unlike the first embodiment, the tyre 11 has the size 255/40R20, that is to say a nominal section width SW=255, a nominal aspect ratio AR=40 and a nominal rim diameter in this case equal to 20. The tyre 11 of the second embodiment has a sidewall height H defined by SW×AR/100=102 95, preferably H≥100.

[0146] The marking also comprises a load index LI ranging from 98 to 116, such that LI≥LI′+1 with LI′ being the load index of an EXTRA LOAD tyre of the same size according to the ETRTO 2019 Standards Manual. Preferably, LI′+1≤LI≤LI′+4, and even LI′+2 LI≤LI′+4.

[0147] A tyre of size 255/40R20 in its EXTRA LOAD version has a load index equal to 101 as indicated on page 34 of the part Passenger Car Tyres—Tyres with Metric Designation of the ETRTO 2019 Standards Manual. Thus, the load index LI of the tyre 11 is such that LI≥102, preferably 102≤LI≤105 and even 103≤LI≤105 and in this case LI=104. This load index equal to 104 corresponds to the load index of a HIGH LOAD CAPACITY tyre of size 255/40R20 as indicated in the ETRTO 2021 manual. Thus, the tyre 11 is indeed of the HIGH LOAD CAPACITY type.

[0148] The tyre 11 is therefore such that 0.82≤H/LI≤0.98 and preferably 0.88≤H/LI≤0.98, and in this case H/LI=0.98.

[0149] For such a size, the ETRTO 2019 Standards Manual indicates, on page 34 of the part Passenger Car Tyres—Tyres with Metric Designation, a measuring rim with a rim width code equal to 9. Thus, use will be made of a rim 200 having a rim width code equal to the measuring rim width code for the tyre size minus 0.5, in this case 8.5, that is to say having a rim width A=215.90 mm.

[0150] Each radially inner 24 and radially outer 26 working layer has an axial width T1=224 mm and T2=210.00 mm, respectively.

[0151] Note that, as in the first embodiment, SW=255 and T2=210 mm satisfy the following relations T2≥SW−75, preferably T2≥SW−70 and T2≤SW−27, preferably T2≤SW−30 and that the ratio T2/A is such that 0.85≤T2/A≤1.00, preferably 0.90≤T2/A≤1.00, and more preferentially 0.93≤T2/A≤0.97 and in this case T2/A=0.97.

[0152] Unlike the first embodiment, the tyre 11 of the second embodiment comprises first and second carcass layers 36, 37 delimited axially by two axial edges 361, 362, 371, 372, respectively, and comprising textile carcass filamentary reinforcing elements 360, 370, respectively, extending axially from one axial edge 361, 371 to the other axial edge 362, 372 in a main direction D3 forming an angle AC which, in terms of absolute value, ranges from 80° to 90° with the circumferential direction X of the tyre 10; in this case AC=+90°.

[0153] Each first and second carcass layer 36, 37 extends in each sidewall 30 and in the crown 12 radially on the inside of the crown reinforcement 16.

[0154] The first carcass layer 36 forms a winding around each circumferential reinforcing element 33 of each bead 32 such that an axially inner portion 3611, 3621 of the first carcass layer 36 is arranged axially on the inside of an axially outer portion 3612, 3622 of the first carcass layer 36 and such that each axial end 361, 362 of the first carcass layer 36 is arranged radially on the outside of each circumferential reinforcing element 33. Each axial end 371, 372 of the second carcass layer 37 is arranged radially on the inside of each axial end of the first layer 361, 362 and is arranged axially between the axially inner and outer portions 3611, 3612 and 3621, 3622 of the first carcass layer 36.

[0155] Each axial end 361, 362 of the first carcass layer 36 is arranged radially on the inside of the equator E of the tyre. More specifically, each axial end 361, 362 of the first carcass layer 36 is arranged at a radial distance RNC of less than or equal to 30 mm from a radially outer end 331 of each circumferential reinforcing element 33 of each bead 32. In this case, RNC=23 mm.

[0156] Each textile carcass filamentary reinforcing element 360, 370 of each first and second carcass layer 36, 37 comprises an assembly of at least two multifilament plies 363, 364, 373, 374. In this case, each assembly is made up of two PET multifilament plies, these two multifilament plies being twisted in a helix individually at 420 turns per meter in one direction and then twisted together in a helix at 420 turns per meter in the opposite direction. Each of these multifilament plies has a count equal to 144 tex such that the total count of the assembly is less than or equal to 475 tex and in this case equal to 288 tex.

[0157] Each textile carcass filamentary reinforcing element 360, 370 has an average diameter D1, D2, respectively, expressed in mm, such that D1≤0.90 mm and D2≤0.90 mm, preferably D1≤0.85 mm and D2≤0.85 mm and more preferentially D1≤0.75 mm and D2≤0.75 mm and such that D1≥0.55 mm and D2≥0.55 mm, preferably D1≥0.60 mm and D2≥0.60 mm. In this case, D1=D2=0.62 mm.

[0158] Comparative Tests

[0159] Static Test

[0160] FIG. 6 shows the result of a static crushing test on a tyre of size 205/40R17 similar to the first embodiment but in which the ratio T2/A is equal to 1.01 (tyre shown on the left hand side, in which working layers with T1=180 mm and T2=180 mm were used) and the tyre according to the first embodiment, the ratio T2/A of which is equal to 0.93 (tyre shown on the right hand side). The load applied to each tyre is equal to 560 kg at a pressure of 250 kPa.

[0161] It can be seen that the deflection of the left-hand tyre is much greater than the deflection of the right-hand tyre. To be specific, the distance DR1 from the axis of rotation R to the ground in the left-hand tyre is less than the distance DR2 from the axis of rotation R to the ground in the right-hand tyre.

[0162] Note in particular that the sidewalls of the right-hand tyre are radially straighter than the sidewalls of the left-hand tyre. This can be seen by comparing, at the same radial point on each sidewall, the distances DF1 and DF2 between the outer surface of the sidewall located on the opposite side to the contact patch and the plane SA perpendicular to the axis of rotation R of the tyre and passing through the bearing face of the rim delimiting the axial width A of the rim. This can also be seen by comparing, at the same radial point on each sidewall located alongside the contact patch, the distances DF1′ and DF2′ between the outer surface of the sidewall and the perpendicular plane SA. It is observed that DF1>DF2 and that DF1>DF2′.

[0163] Running Test Simulations

[0164] The inventors simulated the running of the tyres according to the first and second embodiments of the invention mounted on different rims, including the rim having a rim width code equal to the measuring rim width code for the tyre size minus 0.5, in this case 7 for the tyre according to the first embodiment and 8.5 for the tyre according to the second embodiment. The running of the tyres according to the first and second embodiments of the invention was also simulated on rims not recommended by the ETRTO 2019 Standards Manual for the purposes of demonstrating and understanding the technical effect of the invention (rims with a rim width code of 6.5 and 8, respectively).

[0165] For each mounted assembly, a simulation of a running test similar to the load/speed performance test described in Annex VII of UNECE Regulation No 30 was carried out, but under even more demanding conditions.

[0166] During these simulations, the maximum volumic energy dissipation DNRJ of the calendering matrix was recorded in a portion of the single carcass layer for the tyre according to the first embodiment and in a portion of the second carcass layer for the tyre according to the second embodiment, located in the sidewall, and expressed in daN/mm2. The higher this value, the greater the energy dissipation by the tyre structure and the greater the rise in temperature.

[0167] These values were expressed in relation to a relative value 100 below which the energy dissipation is controlled for the size tested and above which the energy dissipation is not sufficiently controlled. This relative value 100 is different for each size tested.

[0168] The gain in exterior bulk of the vehicle with respect to the measuring rim was also calculated. A negative gain corresponds to an increase in the exterior bulk of the vehicle. For a given rim, a gain in exterior bulk of the vehicle is necessarily accompanied by a reduction in the mass of the rim and therefore a reduction in the masses in rotation on the vehicle.

[0169] These values were collated in tables 1 and 2 below for each first and second embodiment, respectively.

TABLE-US-00001 TABLE 1 A (inches) Gain (cm) T2/A DNRJ (Base 100) 6.5 5.08 1.01 117 7 2.54 0.93 60 7.5 0 0.87 37 8 −2.54 0.82 43

TABLE-US-00002 TABLE 2 A (inches) Gain (cm) T2/A DNRJ (Base 100) 8 5.08 1.03 120 8.5 2.54 0.97 73 9 0 0.92 47 9.5 −2.54 0.87 53

[0170] These tests show that the reduction in the ratio T/2A makes it possible to control the dissipation of energy in the portion of the carcass reinforcement located in the sidewall, even under a relatively heavy load and with a pressure lower than the pressure recommended for carrying the corresponding load.

[0171] Thus, in order, on the one hand, to control this energy dissipation and, on the other hand, to limit the increase in the masses in rotation on the vehicle but also the size of the mounted assembly to the benefit of roominess and compactness of the vehicle, the best compromise is obtained by limiting the axial width T2 and using a rim having a rim width code equal to the measuring rim width code for the tyre size, defined according to the ETRTO 2019 Standards Manual, minus 0.5 such that the ratio T2/A is less than or equal to 1.00.

[0172] The invention is not limited to the embodiments described above.