Moulding element comprising a plurality of ribs and at least one rib-free measurement zone

A moulding element for a mould for a tire that comprises a tread provided with a plurality of blocks, each block comprising a contact surface intended to come into contact with a road surface during running, the moulding element comprising a moulding surface for moulding the contact surfaces of the blocks, the moulding surface comprising:

• a plurality of ribs intended to mould fine grooves in the blocks, the ribs having a height (H) of between 0.005 and 1 mm, a width (L) of between 0.01 mm and 0.3 mm, and a pitch (P) between the ribs of between 0.1 and 2 mm, and
• at least one rib-free measurement zone adapted to accept a measurement probe of a three-dimensional measurement machine, wherein the measurement zone has the overall shape of a disc the diameter of which is greater than 3 mm,
• wherein the moulding element further comprises two edges circumferentially delimiting the moulding surface, each of the edges adapted to come into contact with an edge of another moulding element, wherein the centre of the rib-free measurement zone is distant from one of the edges by 15 mm at most.