I just wanted to mention that when I checked with E-Trailer in the summer of 2015 how about getting new tires but only if I could be assured of a recent date of manufacture, I was told by email that while they strive to provide fresh tires to all their customers, they would only guarantee that the tires I receive are with in two years from date of manufacture.
Since I do less than 2,000 miles per year on my trailer, Time is what I must place my replacement on. I contacted trailer tires and wheels.com, and was assured by Michael there that I would receive tires that were less than three months old, and he was personally checking. The tires I received were only two months old. Highly recommend