The center of the tire is worn down to the belts from riding in a straight line. Pure and simple. Now don't get me wrong, I am not a particular friend or mouthpiece for tire companies, it's just from time to time the "sky is falling" attitude mixed with "can't be my fault" further worsened by ignorance can turn a trivial thing into "mass hysteria". There was another example of this in the previous iteration of this board about "flexi-tires". Never did hear how that turned out, but I do know a "hawk from a handsaw when the wind is from the east" (apologies to W.S.) and there was nothing amiss with those flexi PR-2's.
Fretka