The rim is a metal bar of variable thickness and circular shape, which constitutes the outermost part of the wheel (of a cart, a small cart, a wheelbarrow, etc.). The purpose of the rim is to hold together the various wooden parts of the wheel (spokes, fellows, etc.) protecting them from wear caused by contact with the ground.
The internal measurement of the rim corresponds exactly to the circumference of the wheel on which it is placed. The installation was possible by exploiting one of the properties of the metal: expansion. The rim was heated, causing it to expand, and in this expansion phase it was mounted on the wheel, placed on the appropriate workbench (called trabiccolo), using large tongs (cagna) and hammer blows. As it cooled, the rim returned to its initial size and therefore kept the wooden parts of the wheel together.