Thanks guys. I guess it was fairly logical to take a look myself, but my bike's in the garage and it's probably about 15 degrees in there right now! Anyway, at first glance it was obvious that the front and rear were NOT the same size. I took a nut off the rear and measured it with a caliper and it is 17mm and hollow. So, it doesn't look like the st4 rim will fit, if it really uses a 25 mm axle.

Thanks guys!