Bummer... I wouldn't want those tires on my rig if towing and a long way from home..
I had one of those tires as a spare on my 1997 F150 since around 2001 and it never cracked like that.. I know, because I dropped it at least once a year to check its PSI and condition...
I traded the truck for my new one a couple of months ago and it only touched the ground one time for about 6 miles way back in 2002 or so when I picked up a nail in a tire.. It was a used tire when I got it when I got larger size tires on the truck.. (LT265/75/16) I don't know how old it was when I got it, but it still had good tread on it..
Good luck!
Mitch
2013 F150 XLT 4x4 SuperCab Max Tow Egoboost 3.73 gears #7700 GVWR #1920 payload. 2019 Rockwood Mini Lite 2511S.