Tire Blowout problems of the 1999 Ford E-450

Firestone denies that the tires were faulty, they claim that I drove the vehicle with underinflated tires. Before I drive this vehicle on the highway I always check the tire pressures and fluids. I replaced all of the firestone tires before one blew out on the front and caused a crash. In 26 years of driving numerous vehicles with various tires I have never experienced anything like these tires that have failed prematurely. I kept the remaining 5 of the tires from this set and am having them tested by someone other than firestone. I find firestones explanation of underinflation impossible to believe since I am the one who has properly maintained this vehicle. Nlm.

Inside right rear duel tire blew blewout.

These tires are mounted on a 32 foot jayco class c motorhome on a Ford chassis. The first tire to blowout was the left side inside dual tire at 15000 miles. The second tire to blowout was the outside right dual at 17180 miles. This blowout caused $3243. 00 to my motorhome. Air pressure in the tire was 72psi and the temperature was approximately 90 degrees f. My insurance company, state farm mutual, had the tire inspected and determined that a defect caused the thread separation. I am very concerned about our family's safety since there are still five of the orginial seven tire still on our motorhome. Dy.