I have almost 100% decided on a Supreme Suspensions 3.5" rear and 2" front leveling/spacer kit for my 2013 Suburban LT. I want to run a mildly aggressive MT tire. Can someone put offset/backspacking/etc in plain English? I have watched a number of YouTube videos and for the life of me cannot comprehend what size wheels I need to be looking at. I'm leaning towards an 18" or 20" and want to run the largest tire possible with very minimal to zero trimming. Help?!?