84 stepside wheel question
 

I have an 84 chevy that I have all PB extreme on, Cut bottom of frame and can lay pinch welds. I know I can fit just about any combo under the front. But Im curious if any can give best wheel BS for C10? I want to run 20s, but I feel that I will have to go to a super low profile tire and skinny in the rear to get it to lay out. I think I can go with 18s and get an ok size tire to fit and keep an ok ride. I havent driven it yet. Right now I got a set of 17 with 235/55/17 all the way around. I think BS is 4.5 on all four. Still yet to test fit the bed. Any have any input on front and especially the rear set up for a step side? CPP disc on all four corners, CPP drop spindles on front and rear end is stock (not narrowed).

Thanks fro any help.