The wheel is one of man's most important inventions. It is that the Inca civilizations in Central and South America progressed remarkably wheels, but wheels are the foundation of our modern world of machines.
    The first wheels used by human beings probably did not carry anybody anywhere. Perhaps it was a round, flat stone, placed on its flat side and turned by hand-power or foot-power, on which a of mud was shaped into a bowl or pot.
    No one knows first put the wheel on its edge and made it carry loads that man had previously carried on his own tired back. In any case, wheels from ancient vehicles have been found in is now Iraq, and these have been dated about 3500 B.C. These wheels were made of three large pieces of wood, tied together with bits of copper.
    Once , the vehicle wheel seems to have developed rapidly. Around 1500 B.C. people of Syria, Egypt, and China began to use wheels with supports that reached from the center to the outside . About this same time, wheelmakers added an outer edge which held the spokes in place. In Egypt this edge was made from one piece of wood, bent to form a . In Europe, the edge was made of several pieces of wood fastened together and by a metal band, or tire. This type of wheel carried American settlers to the western part of the country in the nineteenth century. It was strong, and the metal tires were not by sharp rocks. But the wood of the wheels caused trouble constantly because it swelled in weather and became smaller in weather.
    In this general form, the wheel has continued to the present day -- with some changes, especially for automobiles. Tires became air-filled; wheels became solid pieces of steel did not need supports. Early vehicles had large wheels which could carry them muddy places and deep holes. But as roads were improved, wheels could be made smaller. Now we have automobile wheels which are 14 or 15 inches across the middle. Years ago, wheels were about 60 inches wide!
--- 関西学院大