Abstract: A tandem comprising the combination of leveller and covering wheels for use in no-till or direct-till sowing machines. The leveller wheel (11B) has a semipneumatic tread (15B) including a cavity (31) next to the furrow opener disk (55) to make room for the soil removed from the ground by the latter without compacting it. The cavity spans between one- and two-thirds the breadth of the tread. The shape of the cavity follows the profile naturally formed by the elevated rib of soil formed on the ground on which the covering wheel (35) operates. The cross-section area of the cavity is 30% greater than that of the deepest expected furrow. The covering wheel is provided with conical studs (45) which radially project outwards from the tread (39), at a 5° angle to the wheel plane, the flat rolling band being slanted at 30° to the horizontal.