I Emailed Cooper, no phone number to get in touch with them on their site, and was surprised at how fast they got back to me. Good news was that the tires are covered from manufacture's defects for 4 years, including any cracking. They told me to take them to any authorized cooper dealership and they would take care of the issue.
I took them to my local tire shop and they called Cooper directly. Cooper stood by them. They measured my tread depth, 13/32, and pro-rated me two new tires. Because the tires were worn slightly they credited me $409.00 dollars towards the total of $644.00 for two tires.
I was expecting to get screwed, but Cooper surprised me and stood by their product.
I'm glad they took care of you. I had the same problem last year with my 285's. I was 1500 miles from the dealer I bought the tires from, but I took them to a cooper dealer in Des Moines. The manager seemed pretty shady and unwilling to work with cooper in resolving the issue, but he ended up telling me he would "look into it" and try to get a credit if I brought them to him busted off the wheels so he could send them to his distributor. I was leaning towards 35's at the time and happened to find a deal on 315 cooper's online for $150 each so I mounted the 315's and brought the 285s to the cooper dealer.
2 months went by, and after many phone calls and several visits to the dealer, the manager finally said that he and cooper would offer me a $540 credit for 4 tires that had >75-85% tread (~12K miles?), but it had to be the same tire in the same size. Obviously I couldn't have waited 2 months without tires on my rig, and after he saw that I had already bought new tires, I convinced him to see if the credit would be transferable to a later date/city for when I need new tires in a few years.
Then I had to move so I could only contact him via the phone. After many, many, calls and promises to return my calls, the manager finally said that he would see if his boss would let him write me a company check for the credit.
At this point I wasn't holding my breath and wrote the tires off as a loss and figured I'd never see the check. Then surprisingly one day a $540 check from the dealer showed up in the mail ~8 months after I took the tires in.
For the amount of tread my tires had and compared to what you received, it sounds like I might have been shafted by the dealer who may actually have received more credit from cooper but cut me a check for a lesser amount and kept the difference. Regardless, I'm just glad I got something for them.
I really like these tires, I just hope the nothing goes wrong with these blem's since I highly doubt cooper will stand behind them (although the ebay ad specifically stated they have a cooper warranty)
I try to be careful and park in the garage or shade as much as possible, but I'm not sure exactly what causes this cracking.
FWIW, I have the non-cracked spare 285 cooper (~80% tread) in my garage if anyone is interested.
