2018 GMC Savana Passenger 3500 12 PASS VAN RWD

MY 2018 VAN IS AN EXPLORER CONVERSION WITH 13000 MILES ON IT. IT WAS TAKEN TO GMC FOR REPAIRS FOR WHAT THE TECH IS CALLING A "DEATH WOBBLE". BASICALLY THE VAN AT UNPREDICTED TIMES GETS INTO A ROUGH SHAKING IN THE FRONT END THAT FORCES YOU TO STOP. THIS HAPPENED WHILE BRAKING GOING DOWN STEEP GRADES (5%+), ALSO TURNING ONTO A SLOPED ROAD AND AGAIN JUST TRAVELING ON A HILLY ROAD WITHOUT AND USE OF BRAKES. DEALER FOUND THAT 3 OF THE 4 RIMS WHICH WERE INSTALLED BY EXPLORER CONVERSION VANS ARE WARPED OR BENT. THE TIRE SIZE INSTALLED IS 20" WHICH IS DIFFERENT THAN THE STOCK SIZE OF 16". THE CURRENT TIRES ARE PIRELLI SCORPION VERDE 265/50/R20. THE VAN HAS ONLY BEEN DRIVEN ON STANDARD ROAD AND NEVER COLLIDED WITH OR RAN OVER ANY OBJECT IN THE ROAD. UNKNOWN AT THIS TIME IF REPLACING THE WHEELS WILL FIX THE ISSUE DUE TO ISSUES OBTAINING REPLACEMENTS. BIGGER CONCERN IS 3 OUT OF 4 WHEELS FAILING UNDER NORMAL ROAD CONDITIONS AND USE.

AFTER WAITING MY TURN TO PAY A TOLL ON THE OHIO TURNPIKE EXIT IN TOLEDO, THE VAN DID NOT STOP WHEN I APPLIED THE BRAKES AND I RAN INTO THE BACK OF THE CAR AHEAD OF ME. MY VAN BRAKES HAD BEEN WORKING AS WE EASED UP TO THE TOLL BOTH WITH ABOUT 6 CARS AHEAD OF ME. I HAD MY FOOT ON THE BRAKES THE WHOLE TIME. WHEN I WAS SECOND ON LINE, I EASED UP ON THE BRAKES. BUT, THE VAN WOULD NOT STOP EVEN THOUGH I STOMPED ON THE BRAKES TWICE VERY HARD, IT STIL WOULD NOT STOP.