Originally Posted by
Robert A
I updated item 1 to clarify that I'm asking about rim width, not tire width.
Yes, but the two are not unrelated. Many of the people here who are enthused by wide rims are also running wider tires. And for a given standard tire width, a wider rim will produce an effective tire width that is greater. The advantages of a wider tire profile in terms of ride comfort and rolling resistance favor a wider rim. To take best advantage of aerodynamic effects, one might prefer a narrower tire profile.