The narrow 255s should not rub as much as the wider 285s. The main spots that 285s rub is when turning and they contact the back of the front wheel well (firewall). The outside edge of a 285 has a larger arc when turning than the 255s.
Also the 255s (being narrower) won't rub the UCAs like a 285 will.
If you are only running a suspension lift (no body lift) they will probably run when fully stuffed in front. My 32s will top out and rub on the top of the inner fender liner. (my suspension flexes well and my front will compress to the bumpstops)
If you never rub, congratulations. I'm sure the 255s will have minimal rubbing over the 285s.
Looks good.