Bend, but not break. Steel will bend and still hold air, allowing you to stop the car or limp it along. Alloy is harder and will crack and break.
One of the other reasons I like steel is that it will bend. If you hit something hard enough the steel will bend on your rather cheap rim before breaking something more expensive. It's like a fuse for impact damage.
Lupin: Oh really, fool?
Me: I wanted to put in another comment but couldn't think of anything so I went with the stupid route.
Lupin: So you admit to having done something completely pointless; I see.
Me: I did... your point is?
Lupin: Pointing out the pointlessness was my point.
/me braces for the onslaught of people going "Cool story bro"