Ray,
Contact Steve G - smg914 by PM or email, as he has a partial set & was trying to collect a full set of SP57's for his Sahara Beige beauty at one point, but don't know if he still is.
I was trying to get Dunlop to repop those great SP57's as part of their vintage tire line, but still need to get greater numbers from the other models & makes/marques which also mounted 165HR15 SP57's as OE, such as Alfas, BMW 2.8/3.0, 911/912/912E, etc.
You may want to get another wheel to use as a spare with a new tire, as that star mag-style steelie looks to be in great condition too for a CW with a steelie wheeled car looking for a nice show one. So it may be salable too, either with the tire or separate.
Post it in Parts & the question/offer to sell link to parts in the O&H forum too, as well as the other usual web commerce places for 914 stuff.