For Yokohama Tyres, I always just phone them to check the next delivery schedule.
As of this morning, following is the info from them on the Advan Neova AD-08R;
205/50/15: about 20 in stock
225/50/16: out of stock, no delivery info, the earliest would be June.
215/45/16: about 20 in stock
245/40/17: out of stock, about 6 to be delivered around 21/May, no future delivery info yet
215/40/17: out of stock, no delivery info, the earliest would be June.
255/40/17: out of stock, no delivery info, the earliest would be June.
Kaz