I just bought two steer tires from Goodyear and the truck tire dealer here in Tyler, TX was excellent and very helpful. I visited and inquired about the price one afternoon and we discussed the age issue. I had read all their website had on it and he explained that all the tires have lived in a controlled dark environment in warehouses up to this point and that Goodyear warrantees the tires per when installed. The four tires he had in stock in my size were dated late in 2008 and I agreed to purchase two for my front tires. I scheduled a day to bring the coach in and when I arrived he took me back to pick out the tires. He had received two new tires and left them on top for me. These were dated 0810 and he sold me these instead of rotating his stock. He very emphatically stressed covering your tires as much as possible because the problem with tire degradation is in exposure to light.
So I recommend finding a good tire dealer and spend a little time talking to him about your concerns. This sales manager checked over my older rear tires, bought back the tires I was replacing, figured out what pressure all my tires should be running at, gave me a good price, made sure his best tire guy worked on my aluminum wheels, and took care of my mail in rebate. Two different tire service reps have told me the age is not as big a concern as the tire pressure and the care you take of them. Oh yeah and cover them up when not driving! Did I mention that.