Pneumatic vehicle tyre comprising a carcass (3), wherein the carcass (3) has two carcass plies (31, 32), wherein each carcass ply (31, 32) has reinforcements which are arranged inside the carcass ply (31, 32) substantially parallel to each other. The problem addressed by the invention is to provide a pneumatic vehicle tyre which likewise creates a high quality impression of sufficient robustness to a viewer and, in the process, is cheaper to produce and has a reduced rolling resistance. The invention is characterised in that the product EF1 of the average modulus of elasticity of the reinforcements, as measured with an extension of 2%, of the first carcass ply (31) and the thread density of the reinforcements of the first carcass ply (31), and the product EF2 of the average modulus of elasticity of the reinforcements of the second carcass ply (32) and the thread density of reinforcements of the second carcass ply (32), satisfy the relationship EF1>EF2.

Each of at least two layers of a carcass reinforcement has a breaking force per unit width higher than 2250 daN/dm. The minimum strength per unit width, measured for an elongation of less than 10%, of a second layer of carcass reinforcement is strictly greater than a value equal to 20% of the minimum strength per unit width, measured for an elongation of less than 10%, of a first layer of carcass reinforcement. The reinforcing elements of the two layers of carcass reinforcement have a thread count of less than 750 tex. The elongation of the reinforcing elements of the second layer of carcass reinforcement is greater than 4% under a force of 20 daN, and the secant elastic modulus values under tension at 10% elongation, Mt, Mj, satisfy the relationship Mt/Mj≧1.

A tire design for a heavy-duty vehicle of construction plant type has a crown reinforcement (40) radially on the inside of a tread (10) and radially on the outside of a carcass reinforcement (70). The carcass reinforcement (70) has at least two carcass layers (50, 60) having metal reinforcers coated in an elastomer compound. The carcass layers (50, 60) have respective stiffnesses per unit width R1, R2. Metal reinforcers of a first carcass layer (50) form, with the circumferential direction (XX′), an angle A1, and those of the second carcass layer form an angle A2, such that the angles A1 and A2, and the stiffnesses R1 and R2, simultaneously satisfy the following three relationships: R1*sin 2(2*A1)+R2*sin 2(2*A2)≥(R1+R2)*) sin 2(30°), and ∥A1|-|A2∥<10°, and 0.7≤R1/R2≤1.3. The metal reinforcers have a critical compression buckling deformation DF at least equal to 2.5% and a compression elastic modulus MC at least equal to 10 GPa.

Provided is a pneumatic tire enabling improvement of side cut resistance and suppression of increase in mass. A pneumatic tire 1 includes: a tread portion 2; a pair of sidewall portions 3; a pair of bead portions 4 having respective bead cores 5 embedded therein; and a toroidal carcass 6 disposed between the pair of bead portions 4. The carcass 6 includes a first ply 11 extending on and between the pair of bead portions 4, and a second ply 12 disposed, in the tread portion 2, outward of the first ply 11 in a tire radial direction and extending on and between the pair of bead portions 4. The first ply 11 is formed as a layer of first cords. The second ply 12 is formed as a layer of second cords. A thickness of each second cord is 1.1 to 2.0 times a thickness of each first cord.

A pneumatic tire comprises a tread portion, sidewall portions, bead portions each with a bead core embedded therein, and a carcass extending between the bead portions and comprising first carcass cords and second carcass cords. The first carcass cord comprises: a main portion extending from the tread portion to the bead portions via the sidewall portions; and folded-back portions continued from the main portion and folded back around the bead cores from the inside to the outside in the tire axial direction. The second carcass cord extends from the tread portion to the bead portions and terminates on the axially outside of the folded-back portions of the first carcass cords. Young's modulus of the second carcass cords is larger than Young's modulus of the first carcass cords.

The tire has a load index that is at least 118 and two layers of reinforcing elements. Each of the layers has a breaking force per unit width that is higher than 2900 daN/dm. A minimum strength per unit width, measured for an elongation of less than 10%, of the second layer is greater than 20% of the minimum strength per unit width, measured for an elongation of less than 10%, of the first layer. The reinforcing elements of the first layer have a thread count that is higher than 300 tex. The reinforcing elements of the two layers have a thread count of less than 750 tex. The elongation of the reinforcing elements of the second layer are greater than 8% under a force of 20 daN and the secant elastic modulus values under tension at 10% elongation, Mt, Mj, satisfy the relationship Mt/Mj1.

Each of at least two layers of a carcass reinforcement has a breaking force per unit width higher than 2250 daN/dm. The minimum strength per unit width, measured for an elongation of less than 10%, of a second layer of carcass reinforcement is strictly greater than a value equal to 20% of the minimum strength per unit width, measured for an elongation of less than 10%, of a first layer of carcass reinforcement. The reinforcing elements of the two layers of carcass reinforcement have a thread count of less than 750 tex. The elongation of the reinforcing elements of the second layer of carcass reinforcement is greater than 4% under a force of 20 daN, and the secant elastic modulus values under tension at 10% elongation, Mt, Mj, satisfy the relationship Mt/Mj1.

The tire has a load index that is at least 118 and two layers of reinforcing elements. Each of the layers has a breaking force per unit width that is higher than 2900 daN/dm. A minimum strength per unit width, measured for an elongation of less than 10%, of the second layer is greater than 20% of the minimum strength per unit width, measured for an elongation of less than 10%, of the first layer. The reinforcing elements of the first layer have a thread count that is higher than 300 tex. The reinforcing elements of the two layers have a thread count of less than 750 tex. The elongation of the reinforcing elements of the second layer are greater than 8% under a force of 20 daN and the secant elastic modulus values under tension at 10% elongation, Mt, Mj, satisfy the relationship Mt/Mj1.