I found that 17's vs. 21/18 did not handle rough paved roads as well. The larger 21" front rolls over humps and drops better. It's smoother and more controlled.
If you are just riding on smooth roads with the 17s, you probably won't notice it much.
People are crazy and times are strange / I used to care, but things have changed - Dylan
2008 Yamaha WR250R
2012 Yamaha FX HO