Tire Blowout problems of the 2000 Audi S4

While travelling at 35-40 mph, I hit a small bump and tire blew, also these tires were sold as an all weather tire, I was assured by several Audi sales people that they were and at aproximately 200 miles I had to purchase snow tires as these tires are dangerous in even a light dusting of snow. I purchased michelin alpines for snow, but, have not replaced the bridgestones for normal driving as competitive tires would be at least $800 due to the size and speed rating. ( dot number: ).