From the 2002 Long Frame on, the rear rim is 5.5 inches and came with a 180 tire. Yet, some have found the same issues and dropped to a 170 on the 5.5 inch rim.
I have a 2000 Ducati Monster and the only time I had a 180 rear tire that worked well was a Pirelli track tire (used). The stock 180 and a Dunlop I tried all made it turn slower. I switched to a 170 and it was night and day .... however I did have to raise the rear suspension and drop the forks slightly.
Same on my V11 ...... it just works sooooo much better with a 160. I'll need new tires this spring so I am glad for all the great feedback here!