I'm running the dirt grips. So far they are holding up well and they are awesome off road. Rock or Mud. Great traction and they really set the truck off compared to the GSA's.
Dirt Grip Webpage
http://dirtgriptires.com/
I got mine from National Tire and Wheel
http://www.ntwonline.com/
also Desert Rat sells them.
They are not cheap but they are in line with the hard core off road tires like the swampers.
2001 H1 Opentop
Former 03 H2 Adventure Series
http://homepage.mac.com/babiak1/