Short answers, pulled from the story.
The oldest surviving wooden wheel and axle combination dates to between 3340 and 3030 BCE. Archaeologists discovered this artifact at Stare Gmajne near Ljubljana in Slovenia, now known as the Ljubljana Marshes Wheel.
Depictions of wheeled vehicles appear on clay tablets from Uruk in Mesopotamia around 3500 to 3350 BCE. A Funnelbeaker culture settlement in southern Poland yielded a Bronocice clay pot showing a wheeled vehicle dated between 3631 and 3380 BCE.
The earliest known examples of these spoked designs come from the Sintashta culture around 2000 BCE at Krivoye Lake. Horse cultures in the Caucasus region soon adopted horse-drawn spoked-wheel war chariots for three centuries.
The primary obstacle appears to be the absence of domesticated large animals capable of pulling carriages. The American bison is difficult to domesticate and was never successfully tamed by Native Americans while horse species became extinct before European arrival.
Aeronautical engineer George Cayley invented wire wheels while James Starley first used them on bicycles. Wire-spoked wheels and pneumatic tires were invented in the 1870s to replace earlier solid wooden designs that had been in use without major modification.