- mount a medium sized wheel (e.g. 5.5”X14”) on the machine with a rim preferably in steel and with a maximum residual unbalance of 10 grams per side; Important: to properly perform the zerosetting of the swinging unit, the wheel rim must be in perfect condition, without deformations or abrasions or dirt in the centring hole or on the plane that rests on the swinging unit. In addition, the centring accessories must be correct for the wheel type and be clean and in perfect condition;