LOCK!!!

Aside from the wheels studs being too short, is there any reason I can't run four 16" aluminum wheels across the back of my dually?

Big trucks do it all the time. The 22" and 24" conversion guys do it, too. Is it just a wheel stud length issue or is there some other reason that it won't work with 16's?

Cuz 16's are ghey.

Boo.

It is a cross between the thickness of the flanges on aluminum wheels and too short wheel studs, and the lug centric design of most aluminum aftermarket wheels.

With the lug centric wheels, there is nothing to center the inner wheels when they are just slid on there since most aluminum dually wheels have 5" centers so that they will fit over Ford, Chevy, and Dodge hubs. Some Alcoa's might be hub centric, they should work with a lug centric outer and longer studs.