tire preassure and nitrous air
 

I have the 21 inch 215 wheels and would like to know what the proper tire preassure should be and if nitrous air will help the ride at all?

Take the tire pressures from the label on your driver's door jamb. If your tire size isn't listed, use the closest tire size.

Using nitrogen has no impact whatsoever on ride quality. Plain old air is mostly nitrogen in any case. All you get out of nitrogen is less chance of water (it is dryer), nice green valve caps, and a thinner wallet.

In addition to no flucutation in pressure due to hot or cold running temps

Also, no condensation build up inside your wheels...

Craig

Are you suggesting that this is a benefit?

Nitrogen actually expands at the same rate as air, so it is not true that you get no fluctuation in pressure between hot and cold. There is no significant difference between the two. If you are following the pressure recommendations that BMW issues, they are only valid for cold tires, whatever is inside the tire.

What you may get with nitrogen is more predictability in that expansion and pressure increase. The issue is that plain old air can have moisture in it if the compressor isn't maintained properly, and it is the moisture that expands at a greater rate than the air. Thus, wet air is less predictable.

It's a gimmick at best when you are talking about a street car/daily driver. take your wife out for dinner instead.

The air you breathe is 78.084% nitrogen.

> no flucutation in pressure due to hot or cold running temps


Not unless someone has repealed the Ideal Gas Law:

http://www.chalkbored.com/lessons/ch...aw-handout.pdf