Was this on brand new tires that had never been run before? If so, they were probably flat spotted real bad. If you want to try and get a decent balance on them, I would drive the truck a bit, then right before they are balanced, drive it for a few miles to make sure the tires are up to operating temperature.
I tried balance powder in mine with minimal success. I'm gonna try 1/2 dozen golf balls in each tire next. I suspect part of my problem is my beadlocks, though.
Swampers also chunk pretty bad when used hard off road, making it hard to maintain good balance using conventional weights. Plus most of them are square.
Pete