Well the dubro's are closer in size, but if you have to enlarge the hole for the bushing, then you have the problem of keeping the hole centered and straight-through.

I might just try the electrical tape trick that I read about earlier in this thread. Average width tape is just a bit wider than the contact surface of the tire. Should make it slick enough that it does not grip the ground if the plane (and wheels) yaws slightly off from the direction of motion (which probably contributes to the wheel-walking and nose overs).