SAN DIEGO (Jan. 23)—Firestone tires on San Diego Transit buses blew out and caught fire because of poor maintenance, a consultant has determined. But this doesn´t let Bridgestone/Firestone Inc. off the hook, because it was responsible for maintaining as well as supplying the tires, according to a San Diego Transit spokeswoman. The $550,000 full-service contract the company had with the city was canceled because of tire failures, including fires begun by exploding tires which incinerated three buses. "Based on the leasing of the tires, despite new servicers, the tires would remain on the buses," the spokeswoman said. "We wanted to make sure there were no quality problems with the tires themselves." Harold Herzlich, the Reno, Nev.-based consultant hired by San Diego Transit in November, determined in a study issued Jan. 19 that "improper and inadequate inflation pressures on the tires" were a major cause of the tire failures, as was friction between dual tires that rubbed together. Overheated brakes also may have been a problem, the report stated.