According to many sources, the wheel was invented in Mesopotamia in about the fourth millennium BCE. By nearly all creationist chronologies, that places it a quite a few centuries ahead of the flood.
While there is some question why it took so long to come up with that invention, surely once anyone is shown a wheel in use, the concept is so simple and obvious and so clearly beneficial that no one would forget it.
For some reason, many cultures didn't have the technology of the wheel until Western civilizations showed it to them.
Examples: Native Americans and Australian Aborigines.
Those are migratory societies that would have benefitted tremendously from the use of a wheel.
If all civilizations are descended from Noah and his family who surely saw and understood the benefit of wheels, why didn't all civilizations use the wheel after the flood?
An identical question could be asked about other inventions such as Bronze tools.
 http://en.wikipedia.org/wiki/Wheel, referenced on May 7, 2008