Lucky me... I'm 2 for 2 on Shinko delaminations now. The front 757 bubbled up pretty badly, like the picture earlier in this thread, before I noticed it.
Yesterday on the way to work, I noticed a bit of a shake at around 30 mph. Pulled off the road immediately and checked the tires - nothing obviously wrong - and looked for loose bolts or anything. Thought maybe it was my imagination. Then on the way home, more of the shake, so last night I checked the engine mounting bolts and front end, since I had recently finished some fork work. Everything was okay there, so I went ahead and rode to work today, after checking the tire pressures again.
On the way home today, again I felt a bit of a shake, and then even felt like there was something bumping the rear end of the bike to the left, and after about 20 miles, finally started to feel the "flapping" feeling, similar to what I had felt with the front, but not as strong.
Taking a close look at home, I could finally tell it was definitely the rear Shinko 757. I could see cracks in the bottom corners of the tread grooves, and in a few places could feel the tread give under hard pressure from my thumbs.
After taking the rear wheel off, it was really obvious from a few angles where the tire was clearly deformed. I had caught the delamination early.
What really sucks is that I had ordered a replacement from Motorcycle Superstore (under the Shinko exchange program), but it won't arrive before a rally I'm signed up for this weekend! So I'm going to have to run around to pick up a replacement locally to get mounted before Friday. Then I'll have a spare arrive probably early next week.
I've learned (1) Those were some pretty expensive cheap tires. (2) I've been thoroughly underwhelmed by customer service at Motorcycle Superstore.