Same problem and tires this size are hard to find right now for some reason. They have to come off at 25K, what a waste. Highway driving is really bad and spent $200 for road force balance that lasted 1 month. 275/45R21/XL 110W Pirelli Scorpion Zero A/S PNCS
I live in a hot climate that may be causing the foam to move around inside the tire. In any case something is out of balance. At first around 65mph, road force balance corrected it for awhile but now starts around 50mph. I have no clue about these tires.
Looks like Goodyear Eagle F1 is the only option I am finding today.