I like the 190/55 rear over the 190/50. Buy the stickiest street tire you can afford if you want cornering grip. Dunlops, Michelin, Bridgestone, Pirelli all work. The 55 does help tip in better with the busa and adds a bit (few more mm) more road clearance. A recommendation if you are not a short legged person, it to also get adjustable dog bones that allow you to raise the rear of the busa too. I am up 1" over stock. This helps with turn in and corning clearance. Another trick is to shorten the wheel base by going to a larger rear sprocket or by cutting a link out of the chain. I went up 3 teeth in the rear and it moved the rear wheel 5/8" towards the front. Also, a the busa is a wide bike and will hit the engine cases and fairings at stock ride heights when cornering aggressively. I have seen this first hand. Remember these are my recommendations to help you get a better handling and corning busa. And yes I hear it all the time..."That busa cant corner, its a straight line bike!"..... I inside my helmet when I hear this! Then I say to myself they havent met anyone from the org!