Need wheel spec help

I'm looking to jump to 315s as soon as I can figure out wheel specs for the best chance of fitting.
I want to go 17s as there are more choices of tires.
From what I've read in the into to 35s thread 4.0 backspacing seems to be the sweet spot. But I've never figured out what offset to pair with it to look for wheels.
It seems as if 3.5 backspacing has issues with caliper, maybe that was 16s. And -12 offset seems to be the minimum for UCA clearance. Most of this doesn't make much sense to me, but I can only afford to do this once.
Set up is 886 with nitros, CMC, pinch weld smash, fenders cut.
I've posted in multiple threads with no help, so thanks in advance for any responses.

 

With 17s you will have zero caliper clearance issues. As for uca clearance i wouldn’t go more than 4.0” backspace. Offset Will all depend on wheel width you choose.

 

I am planning on going with a 9" wheel. Thanks for the response! I'll start looking for something else as I found some 17x9x4.5 bs -12. I was hoping those would do it.