How many 32nds are left on the tires? Did you ever have them rotated? What does the wear pattern look like? Are all 4 tires worn out? Im sure there's a way to wear out tires in 4700 miles but you'd have chunks of rubber missing and obvious signs of abuse. If all you do is drive on highways then I'd say you have a shot at arguing the tires are bad. Make a not of the mfg date, if the tire is old, it might be drying up and wearing out faster since the rubber is old. Snap some pics and post them up.