Excellent question and i have to use an asterisk to explain. I could say 'it depends' and be right too. Any OEM roller bearing wheel I have measured they typically wear-in and loosen .0002" from new and when they move after that they are on there way to failing. I have measured a few Comps with an .820" wheel and these in pic are Isky .850" wheel. TYPICALLY, I see about .0005" (plus or minus .0001") to start. I have done so many OEM to gage, that you'll see as much variation 'operator to operator' as .0002" even with me measuring i may get some lifters that 'start' at say .0006 and the next time i measure it'll get .0005" It's when they get close to .0009" + that it'll concern me. BUT again I've seen some START about .0008" Hope this makes sense!