when i got my set i was told you can't get a tire thicker than 245's for the rear unless you get a fender lip roll.
with the front it depends on what tire. was told bridgestones & michellin won't fit.
i have toyos 235 front and 245 rear and recently rotated them for purposes of delaying buying new tires and they fit okay only downside is that it's a bit noisier with the 245's in front.
hope that helps. maybe you can consult an agent from tire rack or wheels boutique(where i got mine).