Thanks for the Photos.....
I just tossed four Wilderness AT tires from my 2001 Sport because I found a similar looking crack on the oustide tread shoulder block on my front left tire. The crack was approximately 12" long. The morons at Firestone claimed that was only a cosmetic problem probably due to a road hazard. The funny part is the day before the same Firestone dealer checked these tires and found nothing wrong. I noticed the crack after a high speed run to Delaware and back to New York. I did not hit one pothole on the NJ Turnpike!
The Firestone dealer was about to blow me off, but then changed heart and offered to exchannge the tire. Since he was only offering to give me another Wilderness AT tire, I decided not to take the offer, wnet elsewhere and installed new Pirelli Scorpion AT tires. Since I installed these tires I realized how much of a piece of junk those Wilderness AT tires really are!