One thing to remember, don't over do the back tires. (alot more than the fronts) because you won't be able to steer. Just like studding a sled, too many studs and not enough carbide on the skis=can't turn. To much carbide and not enough studs=spin out turn to fast.
I'd also stager the screws so you have more scratch lines. I think you will need more so the tires will roll. It looks like they may want to stop and slide.
Let us know how it turns out and what combination you end up using in your final set up.
Later
Paul