Thanks XJ Marc for answering the milage question, to add, every mud terrain tire will get different milage too. I know tires have already been purchased, but if you want a long life mud terrain tire, BF Goodrich hands down, I run them on my Daily driver and I currently have around 40K miles on a set, I will probably get another 5k or so out of them, but great tires.
Blems are the way to go, I recently purchased a 42" irok off the interco blem website for $125 plus $50 to ship... this is normally a $400 tire and I can't find whats wrong with it.