daveornee said:If you use a very wide tire on a narrow rim, you risk sidewall or rim failure. This combination causes very sloppy handling at low speeds. Unfortunately, current mountain-bike fashion pushes the edge of this. In the interest of weight saving, most current mountain bikes have excessively narrow rims. Such narrow rims work very poorly with wide tires, unless the tires are overinflated...but that defeats the purpose of wide tires, and puts undue stress on the rim sidewalls.
I am not a bicycle racer, but I am a bicycle wheel builder.
Cross uses quite wide tires.... and I oftern see quite narrow rims. I think the combination of wide tires on narrow rims is bad for rims, tires, and handling.... but it allows the rims to be lighter. I haven't joined in on all the weight savings fads, but I will build wheels with combinations of what I can get that function and provide reasonable value.
FWIW. I wouldn't consider a 700x30/32 CX tire to be very wide ... unless you are comparing it to a 700x20, that is.
But, it wasn't until a about a half-dozen years ago when someone told me that he was using 700x30 CX tires on his MAVIC MA40 rims (622-15) that the notion of something beyond 700x28 on a "regular" road rim would have seemed feasible to me!
To echo daveornee, a 700x38/42 (hybrid) or 700x58 (29er) tire certainly would be undesireable on a 622-15 rim ... but, the latter won't fit in a CX frame ... and, while the former will probably clear a TOURING frame (with the fenders removed?), I'm not sure that a 700x38 tire will clear a CX frame -- at least, it will be hard to clear the fork (there is a difference in tire clearance between a CX fork and a 700c touring fork with braze-on bosses).
A 622-17 rim might be a good option, but they seem far-and-few between, now (Dave, is that the size of the "rims" you've mentioned?) ... and, probably limit you to 700x25 or larger tires.