The tires are Interco's TrXus STS:
http://www.intercotire.com/site35.php
TrXus STS - All Terrain
The TrXus STS, the STS stands for Three Stage Sidewall, is a new concept in all terrain tires. These tires are not intended to be a substitute for the Super Swamper or Bogger tires but a tire for you if you spend a lot of time on the street. Besides working so well on the street it has good off road performance and excels in snow and sand. It is also very much at home in the rocks and will impress anyone with its all around performance. This tire is going to set a new standard in the all terrain category.