Backspacing/offset for ccm leveled 2011 z71

[WS92]

So I'm looking to run some 305/55/20 nitto trail grapplers on a 2011 Z71 tahoe with a ccm 2.5" front 1" rear, I remember hearing that some people on here have done this setup with minor trimming and was wondering if there is any truth to that and if so what were the wheel specs you went with? Nitto has it listed with a 12.6" overall width and I would rather avoid any extensive trimming if possible but may still go through with it for the best result, so I'm kind of unsure about them at this point.

Thanks in advance.