Got it....thought you meant you couldn't find any ones larger than 17"

 

Liking my duratracs so far, but I stuck with the stock 245 size. Lost MPG compared to the factory conticraps though!

 

I am going to throw another tire in this thread. I run Nitto Terra Grapplers. They are offered in a 285/75/17. Almost and inch taller than the 285/70/17 and still work on the 7.5 Ford Steel rim. They are E rated to boot. Just an alternative. Nitto also has the Trail Grappler in the same size if you want a Mud Terrain.

 

My dad ran the firestone tires you mentioned for one set, very poor mud performance and didn't west well for pulling a trailer. He runs BFG's now. I run the Duratracs and love them. I plow and pull and never had an issue with them.