RA-1's are available in selected sizes.
Not all sizes are available yet
, but they are releasing more sizes every few months.
I was able to buy 225/50-15's for the 944 spec from Bryan Shackelford (Toyo's Only)(602-252-3301) over a month ago. He also now has the 275/40-17's for the Turbo, but I bought a set of Nitto NT-01's from him before they were out. The NT-01's seem great so far, unlike the R888's that are completely worthless!!!
C2 Motorsports (local) also has the Toyo's. You have to talk to any of them to find out what sizes are currently shipping.
Also, due tothe huge demand for these tires, you may have to go on a waiting list!
Best of Luck getting your size. If it is not available, do not hesitate to go with the Nitto's.