Nice sizes! BigKriss also has 255s on ET20s IIRC, and he doesn't encounter rubbing. But no hope of snow chains though!

It'd be good to know if having ET22 stops the rub that a 245 can just encounter on the front. I had 245/40x17 (Dunlop Sport 01) on 8 inch ET20s- lowered to M5 height, this worked fine for me.

The trouble is that each model of tyre can have quite different tread footprints, shape profile and even carcass widths. I've read people complaining 245s don't fit up front without rubbing before