I recently purchased a "new to me" coach and had the dealer put new tires on it, as the originals were dated 0550 to 0610, so were 8 years old. They still looked good, and with only 23000 miles, showed no wear.
I discussed tire age with several dealers while in the hunt, and was told that, in that part of California (Palm Springs desert area) at least, the dealers were legally permitted to sell no coach with tires older than 5 years. I bought in Ploenix, and my purchase was not subject to that rule, but I asked the history of my coach and was told it had come from California.
On taking it home to BC. I spoke to a neighbour ( I know, beware attributing knowledge to neighbours) who once owned and operated a tire retreading Co. serving the trucking industry. He confirmed that the biggest enemy of the casing life of a truck tire is heat. That when re-treading, they looked for methods that would limit the time the tire would spend in the oven, so as to get longer tire life and more retreads on each casing. They paid little or no attention to the date of manufacture, but tried to get the casings to outlast the warranty period of the retread.
So this confirms what I now take to be the general rule, if your coach is spending much time in the desert heat in the summer, you will need to watch your tire dates much more closely than if your coach never sees that kind of heat. I respect Gerald's comments above, and will keep the same eye on my new tires that he suggests. My own usage will likely continue to be of a "Low heat" kind, so I expect to get at least 7 years from any tire.
