Has anyone ever have a flat on the surly pugsley. I'd love to turn it into a multi-day off-road tourer - so the fact that I can't find a replacement tire anywhere in a store worries me. My friend is trying to convince me that they just don't flat...

I'm sure any bike will flat. If you run over an upright nail or similar object, even a car would flat. But you know what I mean when I'm asking this question. Under normal riding situations, and riding over objects that would typically cause a flat on most bikes, would the puglsey get a flat?