US-20260124859-A1 - TIRE COMPRISING A TREAD WITH UNIFORM WEAR AND REDUCED NOISE

US20260124859A1US 20260124859 A1US20260124859 A1US 20260124859A1US-20260124859-A1

Abstract

A tire ( 10 ) comprises N1<N2 first and second major transverse cuts ( 81, 82 ) that are formed in axially lateral portions (P 1 , P 2 ) and extend over an axial width greater than or equal to 50% of the respective axial width of each first and second axially lateral portion (P 1 , P 2 ) and have a depth greater than or equal to 50% of the tread pattern height of the tire ( 10 ). At least 50% of the first major transverse cuts ( 81 ) and at least 50% of the second major transverse cuts ( 82 ) have, in at least one zone, a width less than or equal to 0.50 mm. There is at least one central rib j ( 63, 64 ) comprising Mj>1 major transverse cuts ( 73, 74 ) formed in the central rib j such that N1<Mj<N2.

Inventors

Patrick Bervas
Pascal CHOVE
AYAKA IMAMURA
Mathieu GRANDEMANGE
Benoit DURAND-GASSELIN

Assignees

COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN

Dates

Publication Date: 20260507
Application Date: 20230925
Priority Date: 20221003

Claims (16)

1 .- 15 . (canceled)
16 . A tire comprising a tread intended to come into contact with a ground via a tread surface when the tire is running, the tread comprising: main circumferential cuts having a depth greater than or equal to 50% of a tread pattern height, comprising first and second axially outer main circumferential cuts arranged axially on either side of a median plane of the tire, the first and second axially outer main circumferential cuts being axially outermost main circumferential cuts of the tread; a first axially lateral portion that is arranged axially on an outside of the first axially outer main circumferential cut and extends axially from a first axial edge of the tread surface to an axially outer edge of the first axially outer main circumferential cut; a second axially lateral portion that is arranged axially on an outside of the second axially outer main circumferential cut and extends axially from a second axial edge of the tread surface to an axially outer edge of the second axially outer main circumferential cut, the first axially lateral portion comprising N1 first transverse cuts formed in the first axially lateral portion, the second axially lateral portion comprising N2 second transverse cuts formed in the second axially lateral portion, where N2>N1, and each first and second transverse cut is a major transverse cut, extending over an axial width greater than or equal to 50% of a respective axial width of each first and second axially lateral portion and having a depth greater than or equal to 50% of the tread pattern height of the tire, wherein at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts have, in at least one zone, a width less than or equal to 0.50 mm, wherein the tire comprises k≥1 central ribs i delimited axially by first and second axially adjacent main circumferential cuts, the or each central rib i comprising Mi>1 transverse cuts formed in the central rib i, each major transverse cut formed in the central rib i extending over an axial width greater than or equal to 50% of an axial width of the central rib i and having a depth greater than or equal to 50% of the tread pattern height of the tire, and wherein there is at least one central rib j comprising Mj>1 major transverse cuts formed in said central rib j such that N1<Mj<N2.
17 . The tire according to claim 16 , wherein at least 75% of the first major transverse cuts and at least 75% of the second major transverse cuts have, in the at least one zone, a width less than or equal to 0.35 mm.
18 . The tire according to claim 16 , wherein the at least one zone extends over at least 10% of the height and along at least 10% of the length of at least 50% of the first major transverse cuts and of at least 50% of the second major transverse cuts.
19 . The tire according to claim 16 , wherein each first and second major transverse cut has a radially median portion, a radially outer portion arranged radially on an outside of the radially median portion, and a radially inner portion arranged radially on an inside of the radially median portion, the radially median portion extending radially over a height equal to 50% of a height of the first and second major transverse cut, each radially inner portion and radially outer portion extending radially over a height equal to 25% of the height of the first and second major transverse cut, and the at least one zone of at least 50% of the first major transverse cuts and of at least 50% of the second major transverse cuts.
20 . The tire according to claim 16 , wherein at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts have a radially inner portion and a radially outer portion arranged radially on the outside of the radially inner portion, the radially inner portion being the radially innermost portion of the first and second major transverse cut and the radially outer portion being the outermost portion of the first and second major transverse cut, the radially inner portion having a maximum width strictly greater than a maximum width of the radially outer portion.
21 . The tire according to claim 16 , wherein each first and second major transverse cut extends axially from respectively each first and second axial edge of the tread surface until opening respectively into each first and second axially outer main circumferential cut.
22 . The tire according to claim 16 , wherein N2/N1≥1.30.
23 . The tire according to claim 16 , wherein each major transverse cut formed in each central rib i extends axially from each first main circumferential cut until opening into each second main circumferential cut.
24 . The tire according to claim 16 , wherein, with each central rib i other than the central rib j comprising Mm>1 major transverse cuts that are formed in the central rib i other than the central rib j and extend over an axial width greater than or equal to 50% of the axial width of the central rib i other than the central rib j and have a depth greater than or equal to 50% of the tread pattern height of the tire, each central rib i other than the central rib j is such that N1≤Mm≤Mj<N2 or N1<Mj≤Mm≤N2.
25 . The tire according to claim 16 , wherein N2/Mj≥1.15 and Mj/N1≥1.15.
26 . The tire according to claim 16 , wherein N1, N2 and Mj are such that: 0.4 ≤ [ ( N ⁢ 1 / R ⁢ 1 ) - ( Mj × Rj ) ] ⁢ / [ ( Mj / Rj ) - ( N ⁢ 1 × R ⁢ 1 ) ] ≤ 0.6 , and 0.4 ≤ [ ( Mj / Rj ) - ( N ⁢ 2 × R ⁢ 2 ) ] ⁢ / [ ( N ⁢ 2 / R ⁢ 2 ) - ( Mj × Rj ) ] ≤ 0.6 , where: R1 is a pitch ratio equal to a ratio between a minimum distance between two first circumferentially consecutive major transverse cuts and a maximum distance between two first circumferentially consecutive major transverse cuts, R2 is a pitch ratio equal to a ratio between a minimum distance between two second circumferentially consecutive major transverse cuts and a maximum distance between two second circumferentially consecutive major transverse cuts, and Rj is a pitch ratio equal to a ratio between a minimum distance between two circumferentially consecutive major transverse cuts of the or each central rib j and a maximum distance between two circumferentially consecutive major transverse cuts of the or each central rib j.
27 . The tire according to claim 16 , wherein N1, N2 and Mj are such that 0.50≤[Min(N1×R1; N2×R2; Mj×Rj)/Max(N1/R1; N2/R2; Mj/Rj)]{circumflex over ( )}(0.5)≤0.60, where: R1 is a pitch ratio equal to a ratio between a minimum distance between two first circumferentially consecutive major transverse cuts and a maximum distance between two first circumferentially consecutive major transverse cuts, R2 is a pitch ratio equal to a ratio between a minimum distance between two second circumferentially consecutive major transverse cuts and a maximum distance between two second circumferentially consecutive major transverse cuts, Rj is a pitch ratio equal to a ratio between a minimum distance between two circumferentially consecutive major transverse cuts of the or each central rib j and a maximum distance between two circumferentially consecutive major transverse cuts of the or each central rib j, Min(N1×R1; N2×R2; Mj×Rj) is a minimum value of a product of a number of major transverse cuts and a pitch ratio of the first and second axially outer portions and of the or each central rib j, and Max(N1/R1; N2/R2; Mj/Rj) is a maximum value of a ratio between a number of major transverse cuts and the pitch ratio of the first and second axially outer portions and of the or each central rib j.
28 . The tire according to claim 16 , wherein at least 50% of the major transverse cuts formed in the or each central rib i has, in another at least one zone, a width less than or equal to 0.50 mm.
29 . The tire according to claim 28 , wherein the another at least one zone extends over at least 10% of the height and along at least 10% of the length of at least 50% of the major transverse cuts formed in the or each central rib i.
30 . The tire according to claim 28 , wherein each major transverse cut formed in the or each central rib i has a radially median portion, a radially outer portion arranged radially on an outside of the radially median portion, and a radially inner portion arranged radially on an inside of the radially median portion, the radially median portion extending radially over a height equal to 50% of the height of the major transverse cut, each radially inner and outer portion extending radially over a height equal to 25% of the height of the major transverse cut, and the another at least one zone of at least 50% of the major transverse cuts formed in the or each central rib i is situated at least partially in the median portion.

Description

The present invention relates to a tyre for a passenger vehicle. A tyre is understood to be a casing intended to form a cavity by cooperating with a support element, for example a rim, this cavity being able to be pressurized to a pressure higher than atmospheric pressure. A tyre according to the invention has a structure of substantially toroidal shape exhibiting symmetry of revolution about a main axis of the tyre. A passenger vehicle tyre sold under the MICHELIN® trade name in the PRIMACY 4® range is known from the prior art. Such a tyre comprises a tread intended to come into contact with the ground via a tread surface when the tyre is running. The tread comprises main circumferential cuts having a depth greater than or equal to 50% of the tread pattern height and comprising first and second axially outer main circumferential cuts arranged axially on either side of the median plane of the tyre. The first and second axially outer main circumferential cuts are the axially outermost main circumferential cuts of the tread. The tread comprises a first axially lateral portion arranged axially on the outside of the first axially outer main circumferential cut, and a second axially lateral portion arranged axially on the outside of the second axially outer main circumferential cut. The tread also comprises transverse cuts formed at least partially in each first and second axially lateral portion. In spite of having excellent performance aspects, this prior art tyre exhibits uneven wear. Specifically, depending on the vehicle to which this tyre is fitted, one of the first and second axially lateral portions is found to wear down more rapidly than the other. When the wear is such that the tread reaches the regulatory wear threshold, it is then necessary to change the tyre, even though there is still a significant quantity of material able to be worn down on the rest of the tyre. Therefore, the aim of the invention is to increase the service life of the tyre by reducing the uneven wearing of the tread between the first and second axially lateral portions. To that end, the invention relates to a tyre comprising a tread intended to come into contact with the ground via a tread surface when the tyre is running, the tread comprising: main circumferential cuts having a depth greater than or equal to 50% of the tread pattern height, comprising first and second axially outer main circumferential cuts arranged axially on either side of the median plane of the tyre, the first and second axially outer main circumferential cuts being the axially outermost main circumferential cuts of the tread,a first axially lateral portion arranged axially on the outside of the first axially outer main circumferential cut and extending axially from a first axial edge of the tread surface to an axially outer edge of the first axially outer main circumferential cut,a second axially lateral portion arranged axially on the outside of the second axially outer main circumferential cut and extending axially from a second axial edge of the tread surface to an axially outer edge of the second axially outer main circumferential cut,the first axially lateral portion comprising N1 first transverse cuts formed in the first axially lateral portion,the second axially lateral portion comprising N2 second transverse cuts formed in the second axially lateral portion, where N2>N1,each first and second transverse cut, referred to as major transverse cut, extending over an axial width greater than or equal to 50% of the respective axial width of each first and second axially lateral portion and having a depth greater than or equal to 50% of the tread pattern height of the tyre,at least 50% of the first major transverse cuts and at least 50% of the second major transverse cuts having, in at least one zone, a width less than or equal to 0.50 mm,the tyre comprising k≥1 central rib(s) i delimited axially by first and second axially adjacent main circumferential cuts, the or each central rib i comprising Mi>1 transverse cuts formed in said central rib i, each transverse cut formed in said central rib i, referred to as major transverse cut, extending over an axial width greater than or equal to 50% of the axial width of said central rib i and having a depth greater than or equal to 50% of the tread pattern height of the tyre,wherein, in the tyre, there is at least one central rib j comprising Mj>1 major transverse cuts formed in said central rib j such that N1<Mj<N2. The invention makes it possible to extend the service life of the tyre by making the wearing of the tread more even between the first and second axially lateral portions while reducing the noise generated by the tread. Specifically, the inventors behind the invention have discovered that the stiffest portions of the tread are the portions which wear down most rapidly, namely because the engine torque passes through the stiffest portions of the tread. When there is a significant difference in stiffness b