system
Given the following post, respond as if you're commenting on Reddit:
human
Does the air inside of a moving car tire rotate or stand still?
gpt
Yes. Viscous fluids (which includes air) will generally satisfy a no slip condition at obstacle boundaries. This means that the air wants to stick to any surface it is touching. 

Suppose the air is initially stationary and the tire begins to spin. The air in immediate contact with the inside of the tire will begin to spin as well to maintain contact. This is essentially a form of static friction. This creates a thin boundary layer around the inside the tire in which the air is spinning. Just outside this boundary layer, the air is still stationary. Over time, as long as the tire keeps spinning, the remaining air begins to spin, and this is due to the viscosity of the air, which causes air near the boundary layer to start spinning, and the air beyond that, and the air beyond that. 

All of the air will eventually reach the same rotation speed as the tire (let's assume the tire rotates at a constant rate). If the tire stops spinning, the bulk of the air will continue to rotate, but the air in direct contact with the tire will become stationary. Then starts another cascade effect, and the air eventually becomes stationary as well. 

This is just as if you considered a very large vat of syrup which was then set to rotate. The syrup does not initially move, but instead a thin layer of syrup in contact with the walls rotates. Eventually the entire volume of syrup rotates.