Wheel Related Problems of the 2008 Ford E-450

Wheel problem

Purchased this motor-home new in 2009. Drove the motor-home 4 years approximately 25,000 miles with no problems. In may of 2013, I purchased 6 delta essential tires ( lt225/75r16 ) to replace the old tires that would not pass state inspection due to cracks in the side walls. Then we took a 7500 mile trip across the country and back without incident. When we returned home upon routine inspection of my tires I found a bubble on the inside sidewall of a rear passenger inside dual tire. The tire dealer replaced that tire at no cost. About two month later 10/09/2013, we left on a trip to disney in florida. On 10/10/2013 while on I-95 south bound near midway, GA. The driver's side outside rear dual tread separated and the tire blew out resulting in damage to 2 compartments on the drivers side. We had the tire replaced by roadside assistance on the side of the road ( I-95) where it had blown and then found a place to stay for the night. The next morning 10/11/2013, before we continued our trip I performed my usual pre-trip inspection concentrating on the tires and noticed nothing unusual. After about 3 hours into the trip near ormond,florida the passenger side outside rear dual tread separated and blew out resulting in damage to 2 compartment on that side. We also had to purchase a tire from road side assistance to replace that tire due to being out of spares. We finished the trip and returned home without incident. We are currently working with the tire dealer and insurance company in making repairs to our motor-home. My main concern is 3 out of 6 tires failed under 10,000 miles and these tires should be investigated. As a note I do check my tires routinely. . .