I hear ya. No one knows their back spacing! Backspacing and tire size. Need to have both. I’m only gonna run 18’s. I’m gonna use this to tow and haul stuff. That said I’d like to run the widest tire/rim combo I can. The answer isn’t easy to find even though there are tons of these trucks on the road. When I get it back from paint, I’ll measure it and order what’s needed. Just thought I could cheat on here by copying someone else.