Wheel "holds air", how safe are damaged wheels?
 

This guy at my werk often parks next to me. I guess because I park far away and have a nice looking car.

Anyway he drives a BMW I think its a 135is but I don't know BMWs. Well it has about a three inch lip section of the rim missing I guess from hitting a pot hole or something and it just looks so unsafe.

How unsafe is it really if the tire is holding air no problem?

If it's not a wide enough chunk for the sidewall to pop out, should be fine at low speeds.

It's out of balance now and the tire will wear lumps in itself in short order.
If he's a speed demon, it's a vibration induced crash in potentia.

^ everything here,

I have seen some pretty jacked up rims with 7-8" chunks missing and the wheel still holding air. It's mainly a matter of weight and balance at that point. Wear will for sure be uneven but there isn't much of an issue.