Tyre having a load index LI, as defined in the ETRTO Standards Manual 2010, lying in the range between 65 and 105, the tyre comprising: two beads designed to enter into contact with a mounting rim, each bead comprising at least one annular reinforcement structure, defining a median plane perpendicular to the axis of rotation of the tyre and being situated equidistant from the annular reinforcement structures of each bead, two sidewalls extending the beads radially towards the outside, the two sidewalls coming together in a crown comprising a crown reinforcement (80, 90), radially surmounted by a tread provided with a tread pattern formed by motifs in relief, the tread comprising a rolling surface, at least one radial carcass reinforcement extending from the beads across the sidewalls as far as the crown; the tyre having an outside diameter OD and a nominal section width SW, as defined in the ETRTO Standards Manual 2010, in such a way that the following inequality is satisfied: OD / SW > − 0.00082641 LI 2 + 0.11266 LI − 0.185 wherein the average depth of the tread pattern, in an axial zone of the tread having a width equal to two thirds of the axial width of the tread and being centred about the median plane, is greater than or equal to 4.5 mm and less than or equal to 7 mm; wherein the voluminal cavity ratio of the tread pattern is greater than or equal to 15% and less than or equal to 25%; characterised in that the tread is made from at least one first rubber composition having a maximum value of tan δ at 23°C and 10 Hz, determined by scanning the shear strain rate, that is greater than or equal to 0.1 and less than or equal to 0.4, and a Shore A hardness that is greater than or equal to 55 and less than or equal to 65; wherein the tyre further comprises an under layer extending over the whole of the axial width of the tread and arranged radially between the tread and the crown reinforcement (80, 90), the average radial height of the under layer being greater than or equal to 20% of the average radial height of the tread, the under layer being made from a second rubber composition, the maximum value of tan δ at 23°C and 10 Hz, determined by scanning the shear strain rate, of this second rubber composition being less than that of the said at least one first rubber composition from which the tread is made; wherein, in any radial cross section, the transverse radius of the tread, defined as the radius of the circle passing through two axial extremities (45, 46) of the tread and through the intersection of the rolling surface with the median plane of the tyre, is greater than or equal to the nominal section width SW. two beads designed to enter into contact with a mounting rim, each bead comprising at least one annular reinforcement structure, defining a median plane perpendicular to the axis of rotation of the tyre and being situated equidistant from the annular reinforcement structures of each bead, two sidewalls extending the beads radially towards the outside, the two sidewalls coming together in a crown comprising a crown reinforcement (80, 90), radially surmounted by a tread provided with a tread pattern formed by motifs in relief, the tread comprising a rolling surface, at least one radial carcass reinforcement extending from the beads across the sidewalls as far as the crown; the tyre having an outside diameter OD and a nominal section width SW, as defined in the ETRTO Standards Manual 2010, in such a way that the following inequality is satisfied: OD / SW > − 0.00082641 LI 2 + 0.11266 LI − 0.185 wherein the average depth of the tread pattern, in an axial zone of the tread having a width equal to two thirds of the axial width of the tread and being centred about the median plane, is greater than or equal to 4.5 mm and less than or equal to 7 mm; wherein the voluminal cavity ratio of the tread pattern is greater than or equal to 15% and less than or equal to 25%; characterised in that the tread is made from at least one first rubber composition having a maximum value of tan δ at 23°C and 10 Hz, determined by scanning the shear strain rate, that is greater than or equal to 0.1 and less than or equal to 0.4, and a Shore A hardness that is greater than or equal to 55 and less than or equal to 65; wherein the tyre further comprises an under layer extending over the whole of the axial width of the tread and arranged radially between the tread and the crown reinforcement (80, 90), the average radial height of the under layer being greater than or equal to 20% of the average radial height of the tread, the under layer being made from a second rubber composition, the maximum value of tan δ at 23°C and 10 Hz, determined by scanning the shear strain rate, of this second rubber composition being less than that of the said at least one first rubber composition from which the tread is made; wherein, in any radial cross section, the transverse radius of the tread, defined as the radius of the circle passing through two axial extremities (45, 46) of the tread and through the intersection of the rolling surface with the median plane of the tyre, is greater than or equal to the nominal section width SW.