Does this mean you will carry two different spares for the road? I can't see how this is a good idea. My first call was to Rickson. At the time delivery was going to be 6-8 weeks. My local Les Schwab had Vision wheels in 2 days. If you want to save some coin find a decent used 19.5" tire only to carry as a spare. If necessary the local roadside assistance should be able to swap alongside the road.
My first 19.5's were 245/70/R19.5 Toyo 608z. They were a nice tire. Too agressive for street use only. I'm now running 19.5 BFG's with street tread. They roll really nice down the road. Very happy with the BFG's. I think they use the same casing as Michelins.