Sometimes it isn't your car's tires, but rather the wheels that the tires are mounted on that cause your car or truck to vibrate when driven.
Have you ever noticed little metal squares, that look a little like small refrigerator magnets, stuck along the edge of your car's wheels? Those are wheel weights, and they're used to balance your wheels. If you want to take a look, turn your steering wheel as hard as you can to one side (when your car is parked) so your wheels turn outward. It's not uncommon for wheel weights to be mounted on both the inside and outside of the wheel.
While you're in there, if you notice any mud or other debris clinging to your wheels, wipe it off.
Unbalanced wheels are a common cause of car vibration, and though this is a difficult problem to diagnose on your own, it's fairly inexpensive to have a shop check out and balance for you.