A few months ago I put brand new KendaCross's and Mr. Tuffies on my MTB. I was on my daily 14 mile ride (5 miles of pavement and 9 miles of gravel) today when my rear tire developed a big bulge. After thumping my way home and removing the tire I found that the tire fibers in the area of the bulge on the inside of the tire had all been worn to a frazzle. The bulge was about 2" in diameter and directly over the area where the ends of the Tuffie overlaps. However, there was also a 1/16" diameter puncture in the middle of the bulge. The tire did not go flat.
Upon inspection, I noticed that the front tire is also developing a bulge in a place where the tire has been punctured, but I haven't yet removed that tire to see if it's where the Tuffie overlaps. There is also one more tire puncture in the front, but that spot hasn't yet developed a bulge.
It kind of looks like the Tuffies prevent flats, but in their place the tire fibers wear away and a bulge eventually developes.
Anyone experienced anything like this?