Originally Posted by
Jeff Wills
Yes. Caliper brake wear on aluminum rims happens. If you don't replace the rim it can crack and the tire blow out. Modern rims have a "wear indicator" machined into the brake track. When the indicator disappears it's time to replace.
I can verify this, as it's (nearly) happened to me several times on my commuter bike. Luckily, before the rim disintegrates it begins to expand in width at the weakest point and a distinct "thump" happens when the brake is applied. Close inspection will reveal the source of the thump, and immediate rim replacement is indicated.
In my experience, this always happens on the rear wheel... for reasons I don't fully understand, because I use the front brake more heavily than the rear. It certainly could happen on a front rim though.
Imminent rim separation; lateral view
Imminent rim separation; radial view... THUMP!
Can't say I wasn't warned!