We have a new theory from another board, and it fits the facts:
The tube & tire are new. The tire may have come with 3 rectangular stickers on the inside that the A&P removed. The adhesive residue remained. The adhesive is corrosive to the tube rubber but not the tire rubber. That's why they're all the same shape.
A poster on another board said that my failures looked liked ones he had that he was able to conclusively track to stickers on the inside of the tire.
__________________
1969 T337E
|