Originally Posted by The Armand

It will be fine, and will work, but the performance of the tire will be compromised. In order to have the best cornering and bump absorbing qualities in a wide tire like that, the rim should be wide enough to be able to seat the sidewalls so they are essentially vertical, not angled down toward the rim. This ensures the tire is properly seated and supported, and the casing is shaped as it was intended.

I used to run 35mm's on some open sports, and then built up a wheelset with some Sun CR18's, and the difference in ride quality was astonishing. WAY comfier and it felt like it cornered much more predictably as well.

I would consider not passing 32mm tires with road rims, because even then, the sidewalls are still not properly supported and performance is compromised. I can't believe I never hear anyone mention this. I've searched this topic as well and all anyone ever says is "it will work just fine," or something along those lines.

Edit: Oh and everything I mentioned above will be greatly exaggerated if you run the tire at lower pressures.