Vibration in the steering wheel usually indicates something wrong with the front wheels or tires. Vibration in the seat of your pants usually indicates a problem with the rear wheels or tires.
A simple and quick check is to swap the front tires with the rear tires and see if the vibration moves from the front to the back.
Also, look at the wheel balancing weights on your tires. If you see more than 2 oz. or there are multiple weights mounted on the rims, you may have a defective tire or the heaviest side of the wheel is mounted close to the heaviest part of the tire. The simplest cure is to deflate the tire, break the bead and rotate the tire 180 degrees, then re-balance the tires.
Tires worn out of round, bent rims or defective tire treads or a damaged tire carcass can lead to vibration and problems balancing the tires.
Vibration problems at normal road speeds is almost always tire or wheel relatated. If you only get a vibration above 70 MPH, that is often caused by dented, bent or out of balance drive shafts. The smaller diameter of driveshafts requires a higher rotation speed before you can detect a vibration.
....Richard