LOS ANGELES (Sept. 11)—Arguments were set to start today in a Los Angeles court in a tread separation case against Bridgestone/Firestone and Ford Motor Co. Catherine Dizon was killed in 1999 when a Firestone tire on the 1997 Ford Explorer in which she was riding allegedly lost its tread, causing the vehicle to roll over. Cristina Hernandez, the driver, and three other passengers were injured. "The Ford Explorer is a safe vehicle," a Ford spokeswoman said on the eve of the trial, adding that 12 years´ worth of data from the National Highway Traffic Safety Administration and the insurance industry showed the Explorer to have superior safety. BFS said a tire failure or recall doesn´t mean the tire is defective. "Tires can fail for a number of reasons, and vehicle accidents are the result of a complex set of factors," the company said in a prepared statement.