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[bmdubbz]

Originally Posted by Ironring Racing

Guys, the OP was asking about emergency tire repair kits, the one from Continental or the BMW Mobility one. The Continental one is good, I have it and haven't heard any issues. I would have ordered the BMW one from Tischer just because it would look better in the trunk, but they can't ship to Canada.

For the other posters, I really can't believe people are still falling for the nitrogen bullsh!t! Really!

78% of the air you breathe (and put in your tires) is nitrogen. Air has the same coefficient of expansion as nitrogen (less than a percent difference). The only reason race teams (of which I've been on several) use nitrogen is because it has less moisture than air from a normal shop/home air compressor. The commercial process of making/isolating nitrogen requires much higher pressures/lower temps than a shop/home 150psi air comp. The pressure of nitrogen storage bottles varies, but can be a couple thoursand psi. This removes much more water from the nitrogen then gets removed from the air.

When water evaoporates, the change from a liquid to a gas state increases the volume in the tire, so the benefit for some forms of racing where the tire temperature increases substantially is that as the tire warms up, there would be less of a change in pressure.

For street cars, with street tires, that are wet mounted (soapy water is applied with a sponge/dabber around the rim and tire to make mounting easier), on top of the fact that the tire already contains normal air before they put nitrogen in to pressure it up, there is no differenece at all. Tires need to be dry mounted, then purged of air, and refilled with nitrogen.

I doubt Costo does that. In fact I've never seen it done in any commercial establishment. For an investment of a few hundred, they can charge $/tire to fill with nitrogen... easy money. It doesn't hurt anything, so if you want to, go for it. As to the drying out, as you can see, if it was dehydration they were referring to, nitrogen would dry out the tires much more than air. It's that without oxygen there's no/less oxydation (aging). However, as you can see from the outside of the tire, which is exposed to all the elements, aging/cracking of rubber is only a concern over the course of decades, likely much longer than you'll own the tires, and unless you're putting a nitrogen blanket over the outside of your tires, they're going to age and crack anyway.

This is a very informative post.

[Ironring Racing]

Originally Posted by bmdubbz

This is a very informative post.

Aw shucks, thanks man.

To most of the posts above, a tire with Nitrogen and a tire with air (78% nitrogen) will both lose the same amount of pressure. Also, they both have the same amount of thermal expansion.

The only post that is correct is it's use in airline tires is based on the fact that it contains less water vapor. With the stated temp extremes water would fluctuate from frozen to vapor, which would change the pressure significantly.

For passenger tires, there is no difference. Agreed, if they're doing it for free, then sure. Just don't get suckered into paying for it, and DON'T think you don't need to check your tires if they're filled with N2, they will lose pressure the same as if filled with air.

[BMW MotorSport]

Nitrogen +1