What's that? You've never wondered why? Neither have we, because it's freaking obvious. But equally obvious is how awesome it would be to test out a square-wheeled vehicle anyway, which is exactly what the Mythbusters guys did, using an older Ford F-Series pickup.
While the full episode is not available online, you can get the gist of the segment by watching the eight clips Discovery has posted, which we've conveniently organized for your viewing pleasure below.