Just for another opinion, I put Cooper SRM II Radials on my 30ft class C. Rating are exactly as your current Michelins so not stronger but definitely less expensive. I love them. The original Michelins were cracking pretty bad so it's hard to compare apples to apples, but the difference in ride on the interstate with new rubber was noticeable.
I'm a huge fan of Cooper tires. I'm sure there are some bad ones out there but I've never put them on one of my vehicles. Michelins are an RV'ers favorite but there are other options. I think we think the Michelins are the best because that's what comes on the RV initially. Definitely good tires but as with everything, it's rubber so it can be variable as to it's longevity depending on use, temperature, weight, etc.