El Amigo tires, on Imperial Ave., I've heard of a place called Joels Tire and have bought a decent set from Corona Used Tires, in Vista (if its still there) on on E. Vista, corner of SOuth Santa Fe. Theres another place on South Santa Fe as well, don't remember the name. All of these places are pretty ghetto and you have more luck if you speak Spanish. I had an S-10 it ate tires for breakfast so I got used ones. Tijuana must have a million used tire shops, I have taken tires down there (even though youre not supposed to drive across w/ tires) to have them mounted & balanced cheaply.