Tire Blowout problems of the 2003 BMW 325

I purchased a 2003 BMW 325i last year . From san diego BMW and I had 3 or more tire blow out ever since , and is all from the same side of the car (left rear) . I got brand new tires , rotation alignment , anything I can think of. From the same dealer I purchased my car from . My last tire blow out was on Nov. 20,2004 from the tire I had repair on at the dealer service dept. )and it happened two days after I had my car service, and tire repair . (I call the service dept. All they can tell me was to get new tires. ).