Inner tire wear, can be caused by the upper control arms and/or the firewall torsion/sway bar bushings....Have you ever had the upper control arms replaced? It could be a lot on the front end or just one thing...Usually the springs won't cause tire wear....If these shops were good, they would have told you what component was bad...switching a tire to the rear....just makes the rear tire wear to the metal....then you'll need two new tires...

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