SWAP THEM OUT! Two years old is nothing. I buy 2-3 year old takeoffs from PU trucks to put on all of my trailers as they age out (10+ years) before I wear them out.
Yesterday I got a nail in a tire on one of my heavy loaded equipment trailer in the middle of nowhere without a spare or a air compressor... my :S It almost made it to a town before it blew (sidewall temp of 155 a few miles before it gave up) so took it off and for $35 I was able to buy a three year old E rated used tire with 40% tread.
No way would I pay $2100 for 6 new tires when I can buy the same tires used for usually $40/tire. I carefully examination the sidewalls (for running low pressure) and inside for any separation plus I reject any tire that take more the 2 oz to balance. Been doing this for decades without any problems.
PS: I own over 10 trailers of various types and YES it put them on my 5er and my son's 5er and YES I temp my tires on a regular basis.
PSS: If you have a IR temp gun, point it up on a clear day and see how low a temp you can get. Yesterday I got a reading of -38 degrees which is the temp at over 30,000 feet. It will read the temp of clouds or water in a lake at 60 mph. Yes, I sometimes get bored while driving. :B