I know the topic of Metzler tire problems has been debated about as much as any topic on tires can be. Speaking only for myself I’ve had just about all the major and popular tires on my Ultras over the years from the original D-402s, to the Metzler ME880s, Avon Venom, Dunlop E-3s and I am now back to the D-402. I liked the Metzlers but the sidewalls started showing small cracks in it, so I changed to the Avons.
Yesterday I went for a ride up the warm an sunny Southern California coast to have lunch at Neptunes Net, a popular stop for motorcycles. There I saw a bike with Metzler tire that had HUGE CHUNKS of it missing from the center of the tire. I was incredulous to this and had to take a picture of it with my phone.

According to one guy whose name I did not ask, the person who rides the bike likes to take jack rabbit starts and chirp the tire as much as he can. Still, even with those riding habits, a new tire (it looked like a new tire to me and some of the others gawking at it) should not start breaking off in chunks.
We waited for the rider to come out which he never did. After a while I got bored and left.

That just does not look safe to me.