Re: WK2 QL with 275/65/18 and 0 offset Rockstar II wheels
You should be good. The offset is what makes my setup complicated. Many guys running same overall diameter on stock wheels without issue. So if you go with a 265 then reduce your offset, then you'll be in good shape.
There's a couple other wheel setups you can look at where guys are running spacers that will show you what your offset will look like, not a tonne are running aftermarket wheels with that offset so you might struggle trying to find a good example.
If I could do it again, I'd probably go with the same tire but with a more appropriate offset.