There are lots of DB/Coker threads over there. If you read through most of them, Cokers are for those who want bias ply looks and know the handling will be crap. The bias tire hides the bad handling. If you drive it every day, DB is the answer.
As far as seperation of the whitewall, if you see the process, it is not possible.
https://talk.classicparts.com/showthread.php?t=8015
Thin spots in the side wall is crap. They shave just enough to get the lettering off the tire before vulcanizing the whitewall on. Customer service? I blew a tire running autocross at GG Charlotte (No fault of DB, My tire caught the lower sway bar mount I hadn't gotten around to shortening) I called Bill as soon as I got off the track, had another tire at my door on Teus. for warranty cost/shipping.....$75.
MY experience with Coker was not good. I had a set I replaced my Sears Guardsmans with and was afraid to drive over 65 ( I usually haul ass....around 80-85 on interstate) The rear end felt like the u bolts were loose when changing lanes. Couldn't keep it straight on the road and yellowing/ browning set in immediately. I have found many who have had this same problem, Fatman has had several sets do this on customer cars, swap over to DB and the problem is solved. Asked them about warranty, I would have to dismount my tires, send them in, they would date code mine then let me know how much they would allow on a new set. Meanwhile I have no tires and no truck. Didn't sit well with me.
I like Coker for their exact reproductions of classic tires and their involvement in the industry, I just won't run their tires on my ride or any I have built.
Most people here know what I do on my DBs........
http://www.youtube.com/watch?v=7zEhDLhWaAA