My auto insurance coverage covers towed trailers. And when I was Class-A / Class-C, progressive included roadside assistance.
Wherever you get it, roadside assistance will be limited to actual guys doing this work in the location that you break down. So it may not matter if you're AAA, GS, or Geico - if you're rural and no one can handle your class of tire, you're kinda out of luck.
Our one break down, we called, got assistance. By the time they had arranged a dispatch (from a major city 1 hour away) - I had limped into Walmart, bought a jack, and changed it myself.