Peter never cut a tire with the fender .. ????
I think he normally keeps the airbags adjusted to keep the fender off of the tire. It is obviously a low speed rig, so ensuring this shouldn't be a problem. Plus... These tires have a sidewall that is over an inch thick. The tread section is far thicker. True braided steel belts (no nylon in these) Load rating "M". I think that the inner fenderwell meets the outer fender opening flush. There is a corner there but no lip.
If he did damage a tire... he can run it to the trailhead woith zero pressure. these deforms very nidely at low pressures, but the weight of a Cruiser is not enough to actually press them flat. (I'm using these same tires on a rig I'm building.. I actually had Peter's shiped to him when I found and bought the tires for my project.)