You could try Centramatics. They are availible here:
http://www.adventureaccessories.com/...re/Wheels.html
Scroll down to the bottom of the page and you will see them listed. You should also be running your tire pressure a little higher. 35 in the front and 40 in the rear is ideal. Which wheels do you have on your truck? If they are the factory steel wheels that is probably your problem. I was talking to someone yesterday that had the streeters and steel wheels on his H1, when he put on swampers they did not balance properly. If its the wheels you will need to go with the aluminum wheels. They ride better on the freeway anyways.