know this isn't much help, but thought I'd mention it......I had these same tires in 255/55-18, at 36 psi on OEM rims, for about 7k - 8k miles, (based on look of tread...they came with car....I only had them for about 2,500 miles) no cupping or any problems, even wear. good enough that tire place bought them from me to resell.