I have searched and read but could not find the answer I was looking for. When running 285's on 16x8 rims what back spacing should I get. Will 4 1/2 be okay or do I need more? These will be installed with the Cognito leveling kit. Thanks in advance.

4.5" backspace should be good. I also have -5mm offset. They rub a little without adjusting the torsion bars. They didn't rub at all after my torsion bars were cranked, but I couldn't take the rough ride so I had to go back down with the bars. Too many frost heaves in Alaska.

I have the Rock Crawler 8x16 steel rims and they fit just dandy with no rubbing, etc. I forget whether they are 4.25 or 4.5 backspacing.