Higher corner speed, you want a 190 for side grip. Average rider speed, if the bike was stock with a 180, that will be perfect. However, certain race tires do not come in 180 anymore... My opinion echoes a few on here. Pures or Q2s. Q2s are what we run at the Race Orange stuff and I can run 35s on them with a good setup at Mid-Ohio comfortably. They will get greasy by afternoon at that pace, but the idea is that they are predictable and feel great. Q2 is my opinion simply due to the fact that I haven't ran the Pures a whole lot...