Ronin's FD rear fenders allow use of up to 345 width rear tires. We built scratch built these ourselves because we simply couldn't find anything short of a fully custom setup that would maintain the FD's classic curves while putting down BIG TIRE in the back. With two rear over-fenders included, providing complete quarter panel coverage you're ready for some serious tire.
For an all out performance setup we generally recommend:
335/30r18s on a 18x12, 7" backspace (+6 offset) rear
For a little more aggressive stance we generally recommend
335/30r18s on a 18x12.5, 7" backspace (+12 offset) rear
Note, the rear fenders are provided smooth, without a gas tank provision since so many of our customers run fuel cells. It's not hard to add a door back in if desired. Alternatively, it's possible to reroute so it's hidden under the corner of the hatch (but outside the hatch seal.)