1976 FORD VAN Tires Problems

IN LESS THAT 2 MONTHS, ALL FOUR TIRES ON MY VAN FAILED. THE FIRST FAILED WHEN THE TIRE TRED CAME LOOSE FROM THE TIRE CASING CAUSING THE TIRE TO BE UNBALANCED. THE SECOND OCCURRED A FEW DAYS LATER WHEN WE WERE TRAVELLING DOWN THE FREEWAY AT 60 MILES PER HOUR. THE TIRE TRED SEPARATED TOTALLY FROM THE TIRE AND THE TIRE LOST ALL AIR PRESSURE. I WAS ABLE TO STOP SAFELY. THE THIRD TIRE HAD TIRE TRED THAT APPEARED TO BE UNEVEN. WHEN I DEFLATED THE TIRE, IT APPEARED LIKE THE FIRST WITH SOFT SPOTS AROUND THE DIAMETER OF THE TIRE. THE FOURTH TIRE HAD A CIRCULAR CRACK AROUND THE SIDEWALL AND LOOKED LIKE IT WOULD HAVE EVENTUALLY BLOWN OUT. IN JULY, I TRAVELLED IN NEVADA AND IDAHO WHERE THE TEMPERATURE APPROACHED 100 DEGREES. THIS MIGHT HAVE HAD AN EFFECT ON THE FIRST 3 TIRES.( DOT NUMBER: 6F66 TIRE SIZE:...