The over fender on Ab-Flug is not the same as Paul Bailey or other rear fender. Ab-Flug only add the over-fender front of the fender near the door and right on the top of the wheel archs, unlike the PaulBailey or the Explosion. It is always possible to run 18"X12" on the rear. As long as you get the right offset. As for the offset, you might want to as Wagz what offset for his HRE, should be close to it.