Heavy goods vehicle tire, having a crown portion covered radially on the outside by a tread, this tread having at least two cut-outs, the central portion of the tread having a width Lc of between 35% and 70%, the crown portion comprising a reinforcement having at least two working layers having reinforcing elements, these reinforcing elements consisting of UHT-grade threads, having a mechanical breaking strength R satisfying the following relation: R≥(4180−2130×D), where D is the diameter of the thread expressed in millimetres, this tread being formed of at least two layers of superimposed material, the material forming the first layer with a breaking elongation of more than 600% at a temperature of 60° C., this tread being such that, in the central portion, the cavity ratio per unit volume is not more than 10% and the surface cavity ratio as new is not more than 10%.

A radial tire comprises a multilayer composite laminate (10) comprising at least three superposed layers of reinforcers (110, 120, 130), the reinforcers being unidirectional within each layer and embedded in a thickness of rubber (C1, C2, C3, respectively), with a first layer of rubber (C1) comprising at least one row of heat-shrinkable circumferential textile reinforcers (110), for example made of nylon or polyester. The first layer radially (in the direction Z) surmounts two other layers (C2, C3) comprising metal reinforcers (120, 130) which are crossed from one layer to the next, in the form of steel monofilaments of a diameter between 0.20 mm and 0.50 mm. The reinforcers (110) made of heat-shrinkable textile material are tapes of thickness denoted “T” between 0.1 mm and 1 mm, and of thickness denoted “W” between 2 and 50 mm.

The invention relates to a radial pneumatic tire (1) for a heavy-duty civil engineering vehicle and aims to reduce the risk of tread separation of the pneumatic tire, during driving on sharp rocks, while ensuring good resistance to cracking of the crown reinforcement. The pneumatic tire (1) comprises a protective reinforcement (5) comprising two protective layers (51, 52), the radially innermost protective layer (51) comprising elastic metal reinforcements with a diameter D1 which are axially distributed according to an axial pitch P1, and the radially outermost protective layer (52) comprising elastic metal reinforcements with a diameter D2 which are axially distributed according to an axial pitch P2. According to the invention, the following relations are satisfied:

D1>D2

P1>P2

P1>=1.2*D1 et P2>=1.2*D2

2.5<=(DI*P1)/(D2*P2)<=5

The invention relates to a tyre comprising a working reinforcement comprising a single working ply, a carcass reinforcement and a hoop reinforcement. The hooping reinforcing textile filamentary element or elements (480), the working reinforcing filamentary elements (460) and the carcass reinforcing filamentary elements (440) are arranged so as to form a triangular mesh in projection on the circumferential equatorial plane (E). The or each hooping reinforcing textile filamentary element (480) is formed by a cord (30) with a triple twist (T1, T2, T3), comprising an assembly (25) consisting of N>1 strands (20a, 20b, 20c) twisted together with a twist T3 in a direction D2, each strand consisting of M>1 pre-strands, which are themselves twisted together with a twist T2 (T2a, T2b, T2c) in a direction D1 opposite to D2, each pre-strand itself consisting in a yarn that has been previously twisted about itself with a twist T1 in the direction D1, wherein at least half of the N times M yarns consist of elementary monofilaments of aromatic polyamide or aromatic copolyamide.

The present invention concerns a radial tire (1) for a heavy civil-engineering vehicle, and aims to increase the resistance to repeated impact of its crown reinforcement (3), when driving over stones, while maintaining good resistance to attacks. The tire (1) comprises a protective reinforcement (5) comprising at least one protective layer (51, 52) comprising elastic metal reinforcers, and a working reinforcement (6) comprising two working layers (61, 62) comprising non-extensible metal reinforcers, the elastic metal reinforcers of the radially innermost protective layer (51) have a elastic modulus in extension of at least 100 GPa and a diameter D of at least 3 mm, and are distributed axially at an axial pitch P at least 1.2 times the diameter D.

A pneumatic tire having a carcass and a belt reinforcing structure wherein the belt reinforcing structure is a composite belt structure having at least one radially inner spiral layer and at least one zigzag belt reinforcing structure located radially outward of said spiral layer. The zigzag belt width is preferably wider than the spiral layer. The spiral layer and at least one of the zigzag belts reinforcing structures is preferably formed of a merged cord of aramid and nylon.

A pneumatic tire having a carcass and a belt reinforcing structure wherein the belt reinforcing structure is a composite belt structure having at least one radially inner spiral layer and at least one zigzag belt reinforcing structure located radially outward of said spiral layer. The zigzag belt width is preferably wider than the spiral layer. The spiral layer and at least one of the zigzag belts reinforcing structures is preferably formed of a merged cord of aramid and nylon.

A two-layer multi-strand cord (60) comprises an internal layer (CI) of the cord made up of J>1 internal strands (TI) and an external layer (CE) of the cord made up of L>1 external strands (TE). The cord satisfies the relationship 100≤MC≤175, where MC=(J×MI+L×ME)/(J+L); MI=200×cos.sup.4(α)×[Q×(D1/2).sup.2×cos.sup.4(β)+N×(D2/2).sup.2×cos.sup.4(γ)]/[Q×(D1/2).sup.2+N×(D2/2).sup.2]; and ME=200×cos.sup.4(α′)×[Q′×(D1′/2).sup.2×cos.sup.4(β′)+N′×(D2′/2).sup.2×cos.sup.4(γ′)]/[Q′×(D1′/2).sup.2+N′×(D2′/2).sup.2], where D1, D1′, D2, D2′ are in mm, α and α′ are the helix angle of each internal and external strand (TI), β and β′ are the helix angle of each internal thread (F1, F1′), and γ and γ′ are the helix angle of each external thread (F2, F2′).

The invention relates to a tire for a heavy vehicle of construction plant type, comprising a working reinforcement (50), a protective reinforcement (60) and a hoop reinforcement (70). The working reinforcement (50) comprises two layers (51, 52) comprising inelastic metallic reinforcers that are crossed and make angles of between 30° and 35° with the circumferential direction, and having a force at break greater than 2500 daN. The hoop reinforcement (70) is formed by a circumferential winding forming two layers (71, 72), radially positioned between the working layers (51, 52), comprising circumferential elastic metallic reinforcers, having a force at break greater than 800 daN. The metallic reinforcers of the protective layers (61, 62) are potentially identical to the reinforcers of the hoop reinforcement, crossed from one layer to another with angles identical to the working layers. These reinforcers are elastic, have a diameter greater than 3 mm and a force at break greater than 800 daN.

The tire for a construction plant vehicle includes a tread and a crown reinforcement arranged radially internal to the tread. The crown reinforcement includes a protective reinforcement, a working reinforcement, and a hoop reinforcement. The protective reinforcement includes at least one protective ply that exhibits a force at break Fm.sub.NSP. The working reinforcement includes at least one working ply that exhibits a force at break Fm.sub.NST. The hoop reinforcement includes at least one hooping ply, each of which includes hoop reinforcing elements that make an angle at most equal to 10 with a circumferential direction of the tire. The working reinforcement is arranged radially internal to the protective reinforcement. A ratio Fm.sub.NSP/Fm.sub.NST is greater than or equal to 0.27 and less than or equal to 0.90.