Here are the largest front wheels/tires and tires I have seen (on the forum at least):
Originally Posted by wwjd15
ar: 11 E92
Wheels w/ Offsets: Volks TE37SL - (F) (R) 18x10.5 et20
Tires / Miles: Hankook RS3 - (F) (R) 285/35/18; New Tires
Suspension: Moton CS with camber plates
EDC Setting: none
Alignment: (F) -2 (R) -1.6 camber 1/16" toe
Fender Modifications: (F) None (R) None
And that fits with no rubbing on a 285/35 RS3 vs a 285/30 R888 that will most likely be wider and more square than the RS3s, so they are probabbly quite similar in fitment.
I have a set of shaved 275/35/18 (classic size) RA-1s that I need to run through this season, and would like to do the same thing and upgrade to 285 for the next (front) tire.