Every time I get new tires, no matter the brand, it feels like I'm driving on ice. The last time which was only a few months ago I was very nervous on the freeway as it really seemed to skip and skate around. After a few days the feeling was gone and it was back to driving like normal.
One thing that may be helpful is to realize that your new tires will behave differently than your old tires. When you drive you subconsciously move the steering wheel back and forth to correct for the road. Since your new tires will react differently than the old tires, the corrections you need to make are going to be different. This means that the speed and force that you apply to the wheel is going to be different and you might in fact be exacerbating the behavior because you are still steering for the old tires.
Try taking it down the highway or freeway with a very light grip in the wheel. Let the truck drift a bit and use very small movements to keep it in line. Once you learn the idiosyncrasies of the new tires I'll bet you find them just as rock solid as the old.