1 pointI have used Pilot power 2TC on my RC51. 120/70 front and 190/55 rear. Most owners call RC51s "Piggies" because they favor stability over flickableness, so the added height of the 55 profile really helps on the turn in. I have tried both and prefer the 55 by far. The only problem is the 190/55 is always the most expensive tyre in the catalog. I am pretty sure the 190/55 did not exist when this bike first came out, so the manual specs the 50.