Tyre for a passenger vehicle, comprising in a meridian plane: two beads intended to be mounted on a rim, two sidewall layers connected to the beads, a crown comprising a tread, the crown having a first side connected to the radially outer end of one of the two sidewall layers and having a second side connected to the radially outer end of the other of the two sidewall layers; at least one carcass reinforcement extending from the two beads to the crown, the carcass reinforcement comprising a plurality of carcass reinforcement elements and being anchored in the two beads by a turn-up around an annular reinforcement structure, so as to form in each bead a main part and a turn-up; each sidewall layer consisting of two axially superposed sub-layers (FE1, FE2), a first sidewall sub-layer delimited by a first axially outermost side constituting a lateral wall of the tyre in contact with the ambient air, and a second axially inner side defined such that said sidewall sub-layer has an average axial thickness E1, and occupying a volume V1; each sidewall layer also comprising a second sidewall sub-layer, a first side of which coincides with the second side of the first sidewall sub-layer, and a second, axially inner side of which is at least partially in contact with the carcass reinforcement, said sidewall sub-layer having an average axial thickness E2, and occupying a volume V2; the ratio V1/(V1+V2) is less than or equal to 0.3 characterized in that the thickness E1 of the first sidewall sub-layer is greater than or equal to 0.7 mm,, in that the elongation at break of the elastomer compound constituting the first sidewall sub-layer is greater than or equal to 200% measured at a temperature of 100°C, and in that the dynamic loss of the second sidewall sub-layer, Tan(δ) max, is less than or equal to 0.10, the dynamic loss is measured on a Metravib VA4000 viscosity analyser in accordance with ASTM D 5992-96, the response of a sample of vulcanized elastomer compound in the form of a cylindrical test specimen 2 mm thick and 78 mm 2 in cross section, subjected to sinusoidal loading in simple alternating shear stress at a frequency of 10 Hz, at a temperature of 100°C is recorded, a sweep is carried out in deformation amplitude from 0.1% to 50% outward cycle, then from 50% to 0.1% return cycle. two beads intended to be mounted on a rim, two sidewall layers connected to the beads, a crown comprising a tread, the crown having a first side connected to the radially outer end of one of the two sidewall layers and having a second side connected to the radially outer end of the other of the two sidewall layers; at least one carcass reinforcement extending from the two beads to the crown, the carcass reinforcement comprising a plurality of carcass reinforcement elements and being anchored in the two beads by a turn-up around an annular reinforcement structure, so as to form in each bead a main part and a turn-up; each sidewall layer consisting of two axially superposed sub-layers (FE1, FE2), a first sidewall sub-layer delimited by a first axially outermost side constituting a lateral wall of the tyre in contact with the ambient air, and a second axially inner side defined such that said sidewall sub-layer has an average axial thickness E1, and occupying a volume V1; each sidewall layer also comprising a second sidewall sub-layer, a first side of which coincides with the second side of the first sidewall sub-layer, and a second, axially inner side of which is at least partially in contact with the carcass reinforcement, said sidewall sub-layer having an average axial thickness E2, and occupying a volume V2; the ratio V1/(V1+V2) is less than or equal to 0.3 characterized in that the thickness E1 of the first sidewall sub-layer is greater than or equal to 0.7 mm,, in that the elongation at break of the elastomer compound constituting the first sidewall sub-layer is greater than or equal to 200% measured at a temperature of 100°C, and in that the dynamic loss of the second sidewall sub-layer, Tan(δ) max, is less than or equal to 0.10, the dynamic loss is measured on a Metravib VA4000 viscosity analyser in accordance with ASTM D 5992-96, the response of a sample of vulcanized elastomer compound in the form of a cylindrical test specimen 2 mm thick and 78 mm 2 in cross section, subjected to sinusoidal loading in simple alternating shear stress at a frequency of 10 Hz, at a temperature of 100°C is recorded, a sweep is carried out in deformation amplitude from 0.1% to 50% outward cycle, then from 50% to 0.1% return cycle.