We have chosen this set up that you see based on many hours of testing with our shooter. Basically they are set up in order of decreasing tread density. This is basically because we saw the green ones, although offering usually better results, they got chewed up pretty good. This set up pretty much voids any need to decrease the first few wheels. Of course we will continue to test this with our final shooter because we are planning on having to change out wheels rather frequently because even in this set up the less dense green wheels still get a little battered. If you want to see more of our shooter prototypes check us out at
http://youtube.com/user/FRC3929
-max