FLY-IN-LOW..........95% rubber is meaningless on coaches.
You are unlikely to wear the tread off tires. The key is the date of installation plus the date of manufacture.
No manufacturer will honor any warranty after six years from installation or 10 years from the manufature date. The sidewall checking or cracking defines when the tire is beyond safe use. There is a ton of information on the internet about tire life. There is also pages of information from this site which you can find with a search.
Michelin may be expensive, but unless you know something we don't know I doubt if I would claim them to be the best. Joe, our Chicago representative on washing with gasoline has worn out more tires than most of us and I expect he will voice an opinion on tires.