Metzeler Gone Wrong

The other day, my dad was tuning a gentlemen's motorcycle on the dyno, and on the last pull my dad felt the bike shake. I heard something coming from the dyno room, but I couldn't figure out what it was. My dad wasn't sure what was going on himself, but he knew something was wrong. He almost thought the bike was ready to blow up by the way it was shaking and by the loud racket it was creating.

When he got it slowed down, he got off and saw a bunch of big black chunks from the tire all over the place. He looked at the back tire to find this:

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The treads came right off the tire! My dad was amazed, as was the rest of us when we saw it later. My dad in all of his 30-something years of experience working on Harley's had never seen something like that before. The tire was a Metzeler anyway, which my dad considers to be junk. Even so, it shouldn't have came apart like that, especially when it hadn't even had 500 miles on it.