Tow Vehicle Tire Question?

Three years ago, I purchased a used 2007 GMC 2500HD with new sticker Michelin LT265/75 R16 Load Range E tires. Only thing I have towed with this was a 28 foot Travel Trailer for 12 miles for a neighbor. I've put on less than 25,000 miles, all city driving. Noticed that the sidewalls are dry rotting and splitting. Checked with a local tire dealer who said that Michelin tires are notorious for sidewall dry rot and he refuses to sell them due to that problem. What are a good tire make? I have a 35 foot Carriage Cameo that I might tow next year, health permitting.
Have read that there are quite a lot of complaints on Consumer Affairs about the same problem. Will attempt to contact Michelin tomorrow to see what they have to say.