I have a 2008 F550 based Earthroamer and have put 50,000 miles on it since we got it (used). It has the air-ride suspension and hutchinson beadlocks. I'm on (I'm pretty sure) my third set of MPT81's. I'm fairly scrupulous about inflation and adhering to the speed rating (which can be annoying). I've been pretty happy with how these tires have worked, both on-road and off. I'm not a fan of driving in packed snow and ice with them, not too different than most M/T type tires. They DO pack up with mud, which was a surprise. I've gotten all of my tires (after the originals) from Expedition Imports and have found the prices to be fair and the service excellent. Finding someone who can mount/balance them can take some homework, the ER owners forum has a few nightmarish stories. I know a handful of ER owners who have experienced failure of one (or more) tires. I suspect prolonged driving at speeds higher than rated may have been a contributing factor. ER's aren't light (mine is about 16,000 pounds, and the newer bigger ones are even chubbier)..I have to remind myself that, as much as I'd like to keep up with traffic, not much that happens quickly in an 8 ton vehicle is good. Periodically I look at tire charts for something different/new; but I've been pretty happy with these. I expect I'll be getting another set later this year.
According to a molded-in statement on the tire, they are grooveable, and I imagine siping can't hurt, although I have no idea what it would do to the wear.
