air still spinning, or no?

[hukilau]

Little brain teaser(mine of course).
Is the air in your tires spinning at the same rate as the wheel?

Is it spinning at all?

When you come to a stop, is it still spinning?

[hifi]

Well, air is bound by pressure, so keeping that in mind yes, it spins at the same rate as the tire in motion, and comes to rest when the tires stop.

[hukilau]

So, a higher pressure means the air would spin faster, lower pressure wouldn't spin the same speed as the wheel?

[hifi]

Now I didn't say "alternates with various pressures" I said "Bound by pressure" . This would mean that at 32psi the molecules that the air contains are all pushing on each other and the outside world (in this case the inside of the tire causing it to inflate). By pushing on each other, they lock each other in place so to speak. I would suppose that they "jiggle" around somewhat, but all in all they are "bound" by the pressure exerted upon them. By increasing this, you most likely only prevent them from "jiggleing" around as much and vice versa if you lowered the air pressure.

[daveleau]

I do not believe that the pressure of the air int he tire would have anything to do with its speed. It may change its rate of acceleration. The friction between molecules and the tire and rim is what would cause the air to spin with the tire. The more pressure, the more compact the molecules and the faster the acceleration and greater the momentum. It would be just the opposite for a low pressure tire. They would spin at the same speed though.

[Wizzard~Of~Ozz]

I think (tho I haven't really thought about this before) that the air inside the tire would be moving, but not at the same rate as the tire.

Twisted reasoning:

the only thing that would move the air in a tire would be friction from the rim and inner tire, (think of a fan with no fins, it won't really move air at it's speed). This would also cause great amount of turbulance in the tire since the rim and the outer tire have different surface areas causing the air to move in a random pattern that would disturb the movement of air in the same direction as the tire and my eyes are starting to cross from thinking about this so I'll stop there.

[hukilau]

Now WOZ, that's pretty darn good sounding to me. I think you and daveleau hit it on the head!
Air closest to the tire wall would be moving faster than in the center due to friction.(I think)
What if it's a cold day, nahhh! Probably the same.

[zskillz]

i believe that wiz on dave were pretty close to correct. the air at the interface of the inner tire would be moving the fastest of all the air within the tire. A good way to imagine it is to think of a small whirlwind perpindicular to the ground.

the inside of the tire interacting with the air inside the tire would push the air in the direction of motion... assuming ideal gas (a fair assumption) that air would travel pretty straight until it hit the tire again, at which time, it would be knocked in the new direction...

on average, it would be knocked in a motion that was similar to that of the spinning wheel

-Z

[Germ]

hifi has it right. The air inside moves in sync with the tire. Ever had a fly buzzing around in your car? Did he slam into the rear window when you punched the throttle? Or the windshield when you slammed on the brakes? No...........he flys around like the car is sitting still. Same thing with the air in your tires. It moves with the tire, no whirlwinds, no eddies.

[Wizzard~Of~Ozz]

Well, if you take a 2 liter pop bottle or some other clear container that's round and blow smoke into it and seal it, then roll the bottle as a tire would, the smoke doesn't rotate with the bottle. meaning the air is stationary inside the bottle, a tire has a rougher interior allowing a fan effect on the air meaning you get random air movements but no actual rotation.

Actually tested this =]