I have had my Terra Grapplers for three years now. I've run over some crazy stuff and wheeled them in Moab for those same past three years. Either they are some pretty tough tires, or I'm very lucky (or maybe a little of both). I've never had a problem with them and don't think that you will either.
That's just my two cents.
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless