What drive roll types are recommended for different wire types on the Miller Multimatic 255?

The Multimatic 255 uses V-Grooved rolls for hard wire, U-Grooved rolls for soft and soft shelled cored wires, U-Cogged rolls for extremely soft shelled wires (usually hard surfacing types), and V-Knurled rolls for hard shelled cored wires. Drive roll types may be mixed to suit particular requirements, such as combining a V-Knurled roll with a U-Grooved roll. (Page 12)