Could just be a bad tire. I tend to order tires by the pallet for the rental company I work for. Pallet will have 10 to 12 tires with rims. We had to get onto our supplier because they weren't rotating there stock.
A couple of the "New" tires they sent us were over 8 years old. We noticed it when we installed the tire on a piece of equipment, and a couple days later, it was flat

Air it up, and it was flat by morning again. At that point, I pulled the unit over to the wash Bay, inflated the tire again, and then soaped it down. Found it bubbling through the tread. That's when we started checking the date codes and raised some he## with them about rotating their stock.