I discovered a "new" source for automobile tires. There is a huge salvage yard in the Sioux Falls area. These guys are a top-notch modernized organization. Doubtful that you could find anything much over ten years old. When Hurricane Katrina hit, they were one of only a handful of salvage yard that could take in new flooded vehicles from dealerships. I scored a set of Michelin Latitude Touring tires with 70% tread for $250.