[volkdent]

Steel is very durable, can put up with being bent and welded and is OK with it.

Aluminum is not very good at handling changes, repeated flexing stresses, and being welded. Aluminum is usually weak right next to the weld.
Unless a wheel is designed to be welded as part of it's construction, I wouldn't want it anywhere near my car. Call up some wheel fabrication places and ask them about it, curious what they'd have to say.

BTW, not saying it can't be done, just that I wouldn't want to be a person in the car. The alloy wheels I've seen welded are designed with a heat shrink effect then welded just to maintain the position, not as a structural component.

Jason