Replaced our rear G670s at 10 years of age. Looked, smelled, and felt new inside and out. Very little to no wear with 36,000 miles. Felt like an idiot.Heavier coaches with wrong air pressures left with mud and dirt on the tires, sitting in strong sun for long times will bleed oils out as will parking on lime or uncoated concrete. Ours is stored inside and we only get occasional use now.
Michelin salesman said ten years life, Store Mgr pulled him aside and said they don't know how long. Goodyear with lots of UV protection additive 10 years under good conditions.
Front G6os rivered and Goodyear would not make them up and under five years old at the time. Blamed it on the coach, a weight, b alignment, suspension, then "they ll do that."
Michelins we have on are all steer axle tires with decoupling grooves.
Only thing that worries me is they have "orange oil" in them demanded by enviros. How long will they last? One tire took 1 ounce and the other 0 to balance them on road force balancer. They ridge great...but how long.