How many shops have tried balancing the tires? As Larry says dynamic balance is very helpful. The GSP 9700 is best for problem cases, not always necessary. After several sets of tires and wheels I eventually changed the knuckle/hub flange and this seems to have cured any shimmies/vibrations that even on-the-car balancing did not solve - time will tell. Turning left or right or going uphill or downhill shifts the weight of the car making the problem more obvious. Alignment is for tire wear or handling problems, not vibration (except in the most extreme cases).

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Brian Toscano