This problem can be found by inspecting the area where the wheel and tire meet. A guide rib or circumference ring is molded into the sidewall of the tire. Measure and distance from the wheel to the guide rib (approx. 1/4 inch depending on tire brand) at the top, bottom and both sides. A variance in this distance indicates a mismounted tire, which will roll out of round and leads to erratic tire wear and vibration, regardless of how well it is balanced. Reseating the bead properly corrects the problem.