I'll be interested to hear what the experts say but my hunch is that a 255 is too meaty for a 7" wide wheel where handling is a priority. You'll end up with a lot of deflection....
Also, until you play with the wheel offsets/fender clearance, I think you'll run into problems at both ends.
IIRC, my 245s are really close to the leaf springs in the rear, would probably rub the fenders in the front.
Keep us posted!!
What are your plans for suspension and motor?
