PN Racing's Optional/Replacement REAR, 11mm, Formula,"Flanged" WHEELS, offer an outside perimeter flange that helps reduce traction rolls by: covering part of the tire sidewall that helps reduce traction, at the sidewall, thus reducing "bite" and helps from traction rolling. As tires wear...reduceing tire circumference... the better the flange works. Smooth Aero-Disk design adds the latest Formula wheel styling while smoothing the air flow around the wheels...a very good choice of wheels.