Yeah, as Cliff says, looks can be deceiving. Motorhome tires almost never wear out before they time out. Read the date codes and search here on the forum for at what age you want to replace them at... and then make your decision.
Some folks are real sticklers on this and replace them at 5 or 6 years old. Some utilize the advice from Michelin and have them inspected, but use them for up to 10 years. Others just run them until they fail and hope for the best.