I've driven my Silverado with Uniroyal Laredo tires for 18 months and 14,000 miles, and they still don't need to be rebalanced. These are the tires that came with the truck, so I don't get any free rebalancing, etc. I've roatated the tires myself twice in this time.
Outside of not needing to be rebalanced, these tires are terrible on anything that isn't dry, smooth pavement. They have a smooth ride, but they float the truck all over the road. Wet traction is acceptable, but snow traction is simply non-existant.
However, when I get my new Michelin LTX's put on at Sams, they will come with free rotations and rebalancing every 6,000 or 7,500 miles (one or the other... one number may be Wal-Mart, and the other one is Sam's). I'm waiting for bad weather to arrive before mounting up the LTX's. Getting as many miles as I can tolerate, out of the crapola Laredos.
I will utilize the free rotations, but I won't have them rebalanced unless I detect a balance problem.