I would use it as the spare. A tire shop might not want to mount it though. I have a friend who used 4 plugs to fill a hole in the sidewall on a BFG 35 once. We came back to his shop from a road trip and I noticed that 3 of his tires were flat. Guess which one was the only one holding air...the one with the "sandwich" hanging out of the sidewall. I'm not saying this was a good idea, just that it can be done.