Below is a hubcap from a 2000 Honda Accord. The red segment is the placement of the airvalve stem. The lug nuts establish pentagonal positions, making 5 different ways the hub cap can bee attached. The animation shows the 5 resulting places where the valve stem could be. One is best, one is marginal, and three are not good at all. Watch how you put your hub caps on!!!

For more on dynamic geometry, visit (For the GeoGebra file behind this graphic, click the picture.)