Hmmm...Age related maybe ? Bet they were much older than 8 years old. Mileage means nothing. The rubber compound on any tire has a limited life based on time.. Tires are manufactured to last an average of 60K miles now a days. National average for normal driving is 10-15 k per year. 4-6 years typically.
Guys.. please check your DOT numbers. If your tires are older than 5-6 years old try to avoid hi-way speeds. The heat and centrifugal forces at higher speeds will help the tread to detach from the carcass causing fender/body damage at the least. Yes, guys will now post how their tires have been just fine that are this or that many years old but think about it for your self..
But It is a fact that millions of older tires of any brand have not done well at old ages. How long would you trust your belts, hoses, wiper blades ? Rubber hardens with TIME.
Non reproduction BFG T/A tires have been made by Michelin since the eighties. Heard of that company ? After bfg and Uniroyal were purchased by Michelin, the T/A tire was no longer manufactured the same way. Only the tire molds were the same. The actual green tire was a Uniroyal steel belted . The "authentic" BFG made T/A was an all Rayon tire, no steel belts. Very few tread separations because of that. Sadly those tires have not been made for over 40 years...