Also, wooden tires wouldn't have much traction. Most (all?) vehicles at this time were not in any way self-propelled. They were pulled or pushed along by an hor

Also, wooden tires wouldn't have much traction. Most (all?) vehicles at this time were not in any way self-propelled. They were pulled or pushed along by an horse, human or other power source. Anyone that's ridden a big wheel can attest that traction is difficult using hard materials for tires.