Join Date: Apr 2002
Location: Terrible Hole, IN
I've heard of people changing one tire size up or down, but not anything as drastic as a 160 to a 190. Not without buying a wider wheel anyway.
To answer your question, the advantage of going from say a 190 to a 180 is that you get a quicker turn in in the corners. Going from the 180 to the 190 will slow down your turning, but will give you a bit more traction.
As far as which is better, well that's personal choice. There's a reason all the pro's use a 180 though.
The God of the Old Testament is arguably the most unpleasant character in all of fiction: jealous and proud of it; a petty, unjust, unforgiving control-freak; a vindictive, bloodthirsty ethnic cleanser; a misogynistic, homophobic, racist, infanticidal, genocidal, filicidal, pestilential, megalomanical, sadomasochistic, capriciously malevolent bully. - Richard Dawkins, The God Delusion