South of San Francisco is the town of Milpitas, where you can find:
South Bay Cycles
408-263-2475
Give Tom a call. If he doesn't have what you need in stock, he can order it, and have it available if you give him a day or two. (It's a small shop so he only stocks the most popular tires).
He's a good mechanic for our old bikes, as well.
Cheers,