On the left is Nitto's NT555R drag radial; the NT05R is on the right. While both tires are 315/35R-17s, there is a pretty dramatic difference in their tread pattern and height. The new DR's tread is a lot more track-specific than its street predecessor. It also is slightly taller thanks to its increased sidewall. The additional side area is stiffer, which Nitto says helps minimize instability at high-speed/top-end.