A very nice couple from West Sac stopped by the shop and asked us to replace their tandem's rear tube, which had sprung a leak on the ride over. I was summoned forth to complete said task, and while they were getting entered into the system I chatted with the husband. He mentioned that it was surprising that the rear had gone flat, as he'd "put two tire liners in there."
Sadly, doubling up on tire liners is not a particularly good idea, and so I figured that a pinch flat was likely the cause of his leak. I was correct, but I'd underestimated the extent of the problem.The entire tread of another tire had been stuffed in there as well. Since the actual tire is an old Schwinn 26" the tire they stuffed in there was slightly too small, and because it was in one piece (unlike commercial tire liners) it couldn't expand to seat properly. So it absolutely chewed the tube to pieces as it moved around on each rotation of the wheel. To make matters worse, the second liner had deteriorated and cracked lengthwise in several places, which was also wearing through the tube.
I took out all the extraneous liners and put in a new tube, which worked fine. I explained what had caused the flat, and he said, "So my fix was the problem...Oh man, my wife's gonna kill me!"