Backspacing for 22's Needed for 88-98 Full Size Stepside

Alright...I REALLY NEED HELP...A.S.A.P. I need to know what backspacing I need to tuck 22's on a bagged (not body dropped) 95' GMC Fullsize Stepside. I want to do 22x8.5's in the front and 22x10's in the back, but I am not sure if I can tuck them in the back without rubbing my bed sides. If I can, what backspacing do I need to order? I have had that problem before that the bedsides get jacked up and all I had were 20 x 9.5's. Would I need to go with a 22x8.5 in the rear to avoid this messing up the bed??? I cannot shorten my rear end because I have a sheetmetal bed that I do not want to cut up. Anybody please help with this...Thanks.

i have 22x9.5 +35mm offset on my fullsize, didnt have to trim any of the bed lip to clear..... should be the same on a stepside...

22x8.5 for the front need about 5.25" of BS, and the 22x10's need 6.75" of BS. On the back, you could actually get away with about 6.5", but it'll be damn close.

Kyle, would that be for a stepside?

6.75" will clear the back fender completely??