OK, OK, OK, here goes. Now I don't want any of you guys to laugh at me here, but this is a way cool thing that you can all do.
I had tire vibration problems with my BFG Radial TA's for a long time. Had them balanced again and again at a shop that I know does a good job. The problem was that they were not perfectly true (round). So no matter how good they were from a balance perspective, if they are out of round or "lumpy" you get a shake when driving.
Here is the simple zero cost solution: . . . . . . Buy a cheap belt sander, . . . Put the tire/wheel in question on the front of the car. Jack up the front and spin the tire while holding the belt sander firmly against the floor facing up. Every time a high spot on the tire passes the sander it is shaved off. Do this untill the tire is perfectly true. then GET THE TIRE REBALANCED.
Your car will rid like it is on glass!!
You can all thank me later!!
Ed