It varies from one manufacturer to another, but generally a 170 will fit on the same wheel a 180 will fit on. The later V11's have a 5.5" wide rear wheel. Here is a screen shot of a chart on the Dunlop website listing recommended wheel widths.
You can see that both the 170 and 180 are listed for a 5.5" wide wheel, and the 160 is listed as fitting a 4.5" or 5" wide wheel. The 170 will also fit a 4.5" wide rear wheel, which was the original tire size for V11's that came with the 4.5" rear wheel. But in both cases, using the narrower tire for that wheel width will result in lighter steering. That is not something everyone wants, but many do.