Okuma 20mm Wide Step Dresser-Side Mounted Grain Dressing Tool

Form or step dressing large hard wide wheels.
10 mm depth x 20 mm wide hand set Grains. Side mounted plate is set to 5mm x 22mm x 19mm blade and set down 5 degree angle into 11mm Okuma shank.
W Tungsten hot-pressed bond.
Suggestions for Wheel grit size.
Part Code, Wheel grit size
BTO-27 30-40
BTO-25 50-60
BTO-23 80-60