Sorry, but that is not a manufacturing defect, it is clearly from UV rays. Look at other cars and you'll see the same effects from the sun. It's commonly known as "dry rot"...and it's bad here in Texas due to the heat and constant UV rays they are subjected to...
Do You Really Need To Replace Those Tires? - Popular Mechanics
It is highly unlikely that DT or Goodyear will warranty these tires as if they did, they'd go broke doing the same with 75% of the vehicles in Texas!
And if you think it's unique to BF Goodrich tires, you're badly mistaken. As I said, any tire can suffer from it, and if you look around you'll see all other makes of tires have it.
IIRC from a previous time I talked to a tire guy that the cracks are from the heat cycles the tires go through. When they are mounted onto a vehicle, UV sun, accelerated age, heat cycles, weight and use all cause the cracks.