Okay, I just measured using my daughter's wooden ruler. The front has roughly 1.5" between the top of the tire and the where the fork legs meets at the top. There is also roughly 1.5" between the tire and the fork leg. So tons of room up front. The rear is a bit tighter- roughly 3/4" in any direction.
I'm tempted by the Mount and Ground W160's, due to the relatively low price and it's a decent all around performer, but looking at the pic on PW's site, it may not fit in the rear...