I have owned trucks for 29 years now and I have never found a real mud tire that will last for very long. It all depends on what you use them for and how you use them.
When I ran gas lines, I bought a set of Dunlop Mud Rovers and i don't think that I got 30,000 miles out of them.
I bought Bridgestone Revo A/T and they wouldn't dig or clean themselves and I don't think that I got 25,000 miles out of a set of them.
The end result is to buy two new tires every year and sell the tires that are on your truck when you buy the two new ones.
That way you can choose if you want them in the front - to get you out of trouble when you get stuck, or if you want to put them on the back - to keep from having to run around all the time in four wheel drive.
A good set of tires is the TSL Thornbirds.http://www.sams4x4store.com/SwamperThornbirds.htm