I use 3 to 3.5" Dave Brown lite foam wheels to get around better on grass. They have some small tread but I think it is just for looks. You can get treaded or untreaded foam wheels. I imagine the foam wheels wouldn't last long on paved runways. Would wear out pretty quick, so I'd go with rubber treaded for that. I'm not sure if treaded or untreaded makes any real difference in handling. The bigger wheels make a lot of difference in grass. Treaded wheels look nicer on a scale plane.