Trying to overhaul the rear hub of a Shimano WH-6600 Ultegra wheelset. Front hub uses 2 size 17 cone wrenches. Rear drive side uses a 17 as well. The non-drive side needs a larger wrench. Since the double sided wrenches stop at 17/18, I was hoping someone knows the exact size of the non drive side nut so I can order just one wrench.