# Nitrogen filled tires question

**URL:** <https://forums.speedlife.net/t/nitrogen-filled-tires-question/52077>\
**Category:** NYSpeed Automotive\
**Created:** [July 24, 2008, 8:07am UTC](https://forums.speedlife.net/t/nitrogen-filled-tires-question/52077 "2008-07-24T08:07:28Z")\
**Posts on this page:** 1\
**Showing post:** 31

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**Author:** ![Fry](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/fry/32/7284_2.png) [@Fry](https://forums.speedlife.net/u/Fry)\
**Post date:** [August 4, 2008, 9:53am UTC](https://forums.speedlife.net/t/nitrogen-filled-tires-question/52077/31 "2008-08-04T09:53:07Z")

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> [@Fry](#):
>
> IIRC an oxygen molecule is 3 angstroms “square” whereas a nitrogen molecule is 4.3 angstroms by 3 angstroms, hence it’s not supposed to permeate through the rubber as fast as oxygen. In theory.
> 
> For a street car, filling the tires with nitrogen at a tire shop is horse shit IMHO. **You’re starting with 78% nitrogen. Going up higher via grease monkey tire shop technique isn’t going to net you much of an increase.**
> 
> HOWEVER
> 
> Any nitrogen production technique I know of will dry the living hell out of it (well south of -50\*F dewpoints), which is good because a lot of the expansion from heating a tire is caused by the water vapor in the air in your tire.
> 
> All that being said, you will never see me pay to put nitrogen in my tires.
> 
> Although I am tempted to slap together a PSA nitrogen generator and offer nitrogen filling services at tracks days and autocrosses, where it actually could make a difference. Hmm…

> [@Nikuk](#):
>
> umm… how did no one mention that measly old atmospheric “air” is 78% comprised of nitrogen?

It’s OK. It was buried in the first response. :zong:

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