I don't see it helping much at all. I think you would probably end up getting rid of your truck before it pays for itself because if the popular equation is right you would have to shave 100 pounds just to see a 1mpg increase if I were you I would invest in a street only tire and try having your tires filled with nitrogen I have read many promising reviews on it and I am about to try it myself since its only $7 a tire at discount depending on the tire size of course
Good luck let us know what you choose