Hello, my name is XXXXX XXXXX X will answer your question about a road speed related vibration.
If the car does not exhibit the symptom at lower speeds, and the vibration goes away when you accelerate beyond 65 (ie. "drive through the vibration") then your new tires are out of balance.
This happens from time to time, the balancing machine is not always perfect and it only takes one wheel being slightly out to shake your teeth out when the proper harmonic is reached.
If you want to test the theory, you can rotate the back wheels to the front. The symptom will then either change the speed at which it presents, be significantly reduced, or (if by some random chance the back tires are equally out of balance) remain the same. In any event, the first step to a resolution is to take the van back to the tire store and have them rebalance the wheels. You may even want to insist that a tech test drives the car with you in the passenger seat so they can experience the symptom and take the rebalance seriously.
In rare cases, the tires can have a factory defect that prevents balancing. Also, the balancing process at most tire stores is done off of the car at relatively low speeds. Sometimes, a high speed, on car balance is the only way to remove the vibration completely.
Just to be sure, when they remove the wheels, have the tech check the tightness of the bolts holding on the spindle assembly and inspect for any wear in the wheel bearings. However, I am 99% sure that a proper balancing will get you back on the road and allow you to drive 55-65 without loosing a filling.
If you have any additional questions, or need clarification, just let me know.Please don't forget to accept my answer; I am only paid when you do so.Best Regards,Stephen