On my Yamaha 600 I stick to factory size, but on my Honda 929 & 964 I drop the 190 for the 180 width as it gives me better cornering.
Another downfall, of not cornering well, with a larger width can be the rim size might be at the max or possibly width of the swinging arm might be rubbed. Because in some situations if he bike is a 'used' bike he prior owner might have put on a broader tyre so you could be looking at two sizes larger. So check your MOM & if you do not have one, then check with a m/c shop.
Lastly a 160 to a 180 is one 'ell of a change unless you are going for appearance. I had a bike with stock 160 & needing a new rear tyre, but only having a 170 in stock I put on the latter & sold it at a reduced price to a customer once we got in some proper tyres----to go back to the 160.
Last edited by Smitty; 03-22-2008 at 11:53 AM.