I'm dealing with tires that are loosing chunks of rubber at the center of the tire. I've seen chunking at the edges but never the center.

Hankook Ventus V12 Evo's with 15k miles on the front with ~ 4/32" remaining (the first two pics). However, the rears (the last pic) are new with 1,400 miles and are starting to show evidence of the same chunking. I can actually peel back the tread in the areas where it has come apart.

Thoughts?