OP originally corrected the data code, but as usually it would be nice to know all the details up front, before 2 pages of speculation starts.
90,000 miles on tires are not telling much about life on them. if you don't know the size and brand.
Michelin makes tires lasting 600,000 miles in commercial size.
I got over 100,000k on Hankooks on my dually pickup and replaced them due the deterioration still with usable tread.
Anyway, sounds like good decision was made as 2 years old "stock" got for free is a good deal and again, I have seen heavy tires lasting for over 20 years with proper care, so what is the problem?