These pictures were just sent to me they came off a 1year old 5th wheel and are OEM INSTALLED soooo truck tire may not be better than trailer tires.
The attached pictures show what he found. The size of the "bubble" was about 1/2 the size of a bowling ball and as hard as the tire itself. The tread was perfect. Mike took it to the Goodyear dealer where they looked inside and found the same size "bubble" inside. No air was leaking. However, it would have surely burst if we had driven it further.
The second picture, #0715, looks like the black thing in the middle is part of the middle, but that it how much the "bubble" covered!
Again, this is a Goodyear Wrangler HT