I have a 3/2 block and spacer lift and need advice on wheel specs

I currently have a 3/2 ready lift and uca’s sitting in my garage, but i’m waiting to find out what kind of wheel i need to run to clear my truck. I’ve heard 275/70r17 is the best way to go without a cmc, but i don’t know a thing about offset or backspacing. The information i’ve seen floating around is all over the place. The stock alloy wheels i’m running now are the 17”x7.5” with 30mm offset. What can i run without problems?

 

My truck came with a 3/2 spacer lift and I am running 285/70r17's on some 17x9 -12 level 8 MK6's. I rub the cab mount occasionally.