In case of industrial products exposed to human eyes, there are two cases. One is produced by industrial designer's hand to obtain good appearance and another one is produced by engineer's struggle against functional criteria. Wheel presented on this site are later. I love wheel produced by engineer. Form of wheel is depend on functional criteria, there is no room for scale of preferable form. But, it's not perfect zero. If there is room for such scale, how does engineer do? Some windows located on the wheel disc. This windows are designed according to functional criteria - radiation of brake systems, accessibility for air inflating , strength, productability, and cost. Former engineer designed a lot of shape of this windows,- circle, semicircle, rounded square, etc. Even it's small, I think the room for selection - shape, numbers, and size of window are remained as elements for preferable form. Is this amateur's opinion? Every time when I see the wheel, I am thinking about engineer's struggle.