Long story, bear with me.

I started to get vibrations at high speeds on my Dodge Caravan 2014. At around 110km/h, I have some vibration in the car and the steering wheel shakes a bit. I can see all the seats in my van shaking like crazy. However, the car feels relatively smooth (small bumpy roads). My son even makes fun of it by doing some amazing shaky vocals.
Anyways here what I did.

OEM Yokohama were EOL (3/32) on one tire. It did not hurt to replace them so I bought a new set of Kumho Solus TA11. I had them installed and balanced on my OEM mags.
Drove a bit, lots of vibration during my 600KM trip. I had them rebalanced again.
Vibration still there. Swapped tire around, garage rebalanced them. Just to make sure, I replaced all the nuts because they were all mismatched. The vibration did not stop (dealer apparently told me I have the wrong nuts too because they aren’t sitting well on the rim…)

I installed my Michelin X-ICE2 with steel rims. Vibration still present.
Brought it to the dealer, they rebalanced my tires (3rd) time. Now, they did some diagnostic to search for the problems, they said they took brand new tires from another van and 70% of the vibration were gone... the 30% left were caused by the rotors... Now the dealership is charging me 5 hours of labor because it isn't on the warranty. I am beyond mad...and yet my problem is still present.

I tried three different set of tires and the vibration was there... why does he say that his tires fixes the issue? Anyone got the same issue here? He did verify that everything else is fine (bearings/struts etc)

Help!

 

When they changed the "tires" did they change the rims as well. Sounds like a our of round rim to me. It will balance ok, but the rim is no longer true