I have wondered about trying something like this.
This wheel was made into a bolt together two piece wheel while enlarging it from 13" to 15". They simply welded a flange to the center of the stock wheel and a flange to the center of a larger wheel hoop.
I am not interested in the two piece part of it, but wondered about just installed a single ring in mine to make a 15" rally into a 17" rally, fully welded with nothing bolted together.
Anybody have any thoughts on the structural aspects of doing this?