Tire Sidewall problems of the 2006 Dodge Ram 2500

A routine visual check of my tires resulted in finding that the outer sidewall rubber is degraded on all four tires. The nature of the degradation is that the sidewall rubber is separating from the core. This is apparent around the entire circumference of the tires. The separations shows as if they were a "fine slice" through the rubber such that the rubber is easily lifted away from the core. There have been no normal (or otherwise) driving incidents or vandalism where such "fine slice" type degradation would have resulted. The "fine slices" appear to start from where the main tread is on the side of the tire and is in a radial shape towards the tire center. These slices range from 1/2" to 2" in length at this time. The tires have been replaced with new tires. The worst case tire has been retained and is in my possession. Digital pictures have been taken and are available. The tires are bf goodrich lt265/70r17, rugged trail t/a with dot code m3ah dr11 4005 load range "e".

The bf goodrich rugged trail tire has numerous cracks in the sidewall. I had to replace one at 15k miles and now more cracks are showing up on the other tires at 30k miles. The tread life is good but the sidewalls are incredibly weak.