Tom,
See Dunlop's fitment chart for the Q2 here: http://www.dunlopmot...tire.asp?id=108
As you can see the Q2 180/55 and the 190/55 will fit both a 5.5x17 and 6.0x17 rims (600,750 and 1000's). Forget the 190/50x17 Q2 for performance riding, its a flatter center and better suited for regular urban street riding and not aggressive cornering.
Q2 on a 600, I would start with the 180/55. Since it will be closest to your stock chassis settings. If you are willing to make small chassis adjustments (and looking for a future in track riding or racing), I would go with the 190/55. The 190/55 Q2 is the same width and height as the 190/55 D211GPA race tire, thus making the transition easier from Q2 to D211GPA.
Both are good choices in the Q2 for track days.
Steve,
I've just purchased a set of Carrozzeria wheels for my R6. I had been running Q2 180/55 on the rear of my stock 5.5" wheel. I see from the fitment chart that this size in the Q2 will fit both a 5.5" and a 6" rim.
Would you recomend I stick with this size or should I move up to the 190/55 for a 6" Rim
Thanks in advance for your suggestion