That is the infamous "Avon wobble". It doesn't do it aon all bikes. IIRC, I could get mine to do it @ 20 mph on one section of road, so I deduced it was a reaction of the tread design vs. the pavement texture.

B ut, it has been mentioned as the only set-back to a really great tire. Terrific in the rain and great turn-in on dry pavement.