I don't know, but I was talking with the tire guy at Sam's club the other day...not as though he was any sort of rocket/tire-scientist, but I asked the question about "old tires". (..."these trailer people are telling me to replace tires after 5 years, regardless of their appearance. what do you think?") He told me an anectdote...some place he was working, he took some tires that had been in a basement warehouse for 4 years...never used, but stored long-term. put them on his truck, and as soon as he got on the highway, it started fish-tailing. before he could pull over, the tread separated, and the tire blew. no damage to the vehicle or anything...but scary.
'73 Safari 23'
'00 Dodge Ram 1500 4x4 QC