Had a set of Thornbirds on my 1999 Z71. At only 10,000 miles, one of the tires tread seperated from the actual sidewall while I was traveling 65mph on the interstate. Interco replaced it, then 3,000 miles later, different tire did the same thing, only this time I didn't pucker as much cause i was going slower. Understand, I had never hit a curb, etc. with these tires, otherwise maybe I could have understood. Rep told me that there is a problem with the sidewall const. and thus the reason for cases of tread seperation. Bottom line, Thornbirds are not made for the highway, or daily drivers. Just not a well constructed tire.