general problems of the 2008 Dodge Sprinter

Kuhmo tire road venture at 215 85r16 tread separated from casing causing minor damage to my 09 monaco covina motor home. These tires came as original equipment on the monaco. This is the fourth of seven of these tires that has failed in this fashion. The tires have been inspected, rotated, and maintained at appropriate air pressure. I contacted kuhmo and they agreed to replace the two tires that threw off rubber on my last trip with the monaco. I just completed another trip (the first since replacing the two original defective tires) and had two more go bad within a day of each other. The monaco has less than 30,000 miles on it. It was not overloaded nor are there any mechanical deficiencies. Both tires were on the rear outside of duals. Both appeared to have blistered prior to tread separation. In the previous incidents, one front and one rear inside dual separated. Both held air allowing transportation to a tire shop for replacement. There must be a systemic problem with these tires. Please investigate and recall if appropriate.