The best places I have found for this is places that specialize in selling used tires.
In Edmonton, we have a place called Dollar Tire. I'm sure there must be someone in your area who offers a similar service.
OR, try a wrecking yard. They dismount tires all the time as part of their auto recycling, to sell the tires and wheels separately when needed. I'm sure they could mount yours too.
This place popped up at the top of google's search results for "used tires san diego", no idea besides that....
http://www.bearstires.com/