Tire Bubble problems of the 2008 Mercedes Benz E350

The contact owns a 2008 Mercedes Benz E350 with continental, conti pro contact tires. The contact stated that while driving 35 mph over a bump in the road, the tires would form a blister or bubble. The dealer advised the tires were unsafe and all four tires were replaced. In addition, the contact stated she has also experienced several blowouts with the tires. She would have all four tires replaced whenever she would experience a blowout. The dealer advised the tires would blowout easily because they were low composing tires. The manufacturer was not contacted. The failure mileage was 34,786.