I have the same set up. I use exclusively used tires on my little mazda, and dodge pickups, and all 4 trailers I use regularly. Our dump has a 4 used tire a day limit, for residents to bring in old tires. Many's the time I brought in my 4 and took out 8 others!
I may not get the first mile out of a tire, but I d amn sure get the last mile out of 'em!