Wheel Customizer

This is a very flexible customizer for generating an almost infinite array of wheels. Customizer allows for typical wheel settings, size, wheel, axle, tire, etc., but also with or without spokes (flat or round), number and size of spokes, etc.I added support for longitudinal treads as well. I tried latitudinal treads, but processing was too intense, even after maxing out the # of elements setting in OpenSCAD. Maybe someone can come up with a better way of doing this... The code is in the file, a