Jeff and Patrick are both trying to help, but say they have to go step by step, and said they aren't allowed to swap from another vehicle. I asked that multiple times, since to me that's the easiest way to troubleshoot this. if you have a truck on the lot with no vibration, then swap and see, but they can't or won't do that.
Jeff said with the case now open with GM, maybe they can replace all 4 tires and wheels, but we'll see....pretty bad when my 11 year old Dodge drove better than this truck!
hope yours is fixed, curious about the updated tires too?
Mark