Originally Posted by smashndash

Some issues with very wide rims, as the title requested

1) If the tire you use (eg Vittoria Corsa Speed, Pirelli P Zero) has a very narrow usable tread or tread cap, and you don’t pump your tires up very hard, you will run out of tread when cornering. It can lead to a slideout.

2) The rims are more exposed to impact. I have several chips in my rims from random gravel/rocks on the road. You can also damage your rims by hitting lips at the wrong angle, such as turning into a driveway.

3) If the reason you don’t like lower pressures is because the tire gets too floppy in corners, then wider rims are great. If the reason you don’t run lower pressures is because the tire starts to feel slow or you’re pinching rubber/damaging rims from impact, wider rims will not solve these issues. They could potentially make things worse - I have no idea.

4) This is less “confirmed” but the wider the rim, the more exposed the tire sidewalls seem. So you may see a slight increase in sidewall slash frequency.

I would go as far as to say that the best, and nearly only reason to go with wide rims relative to the tire (I’m talking about 30mm tires on 25mm rims, not 2.5 inch tires on 35mm rims etc.) is aerodynamics. It’s one of the best indicators for aero stability, once you control for rim depth.

Mountain bikers bought into the wide rim hype because they were running 2.4-2.5 inch tires on 19mm rims. And they run very low pressures + stiff casings, which significantly amplifies the negative effects of tire floppiness. Even after the “revolution”, people are running 27-35mm rims for 2.3-2.6 inch tires. Maybe 40-45mm for 3.0 inch tires. This would be like running a 35mm tire on a 19mm rim. So we are going well past what the MTB community, where this wide rim hype started, has gone.