How many miles does All terrain/mud terrain tires last for on a f-150?

Depends on the tires and what you do with them. Generally speaking mud tires won't last as long a all-terrians. On my Bronco I've gotten abour 35k-40k out of a set of Bridgestone Dueler A/T Revos, and a set of BFG All-Terrian KOs. I got about 30k out of a set of Goodyear Wrangler MT/Rs. I'm on my second set of MT/R's now and it looks like they're going to end up lasting about 30k miles as well.