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General => General => Topic started by: taylor on 23 September 2013, 09:09:42 pm

Title: nitrogen tyres.
Post by: taylor on 23 September 2013, 09:09:42 pm
the wife,y bought some tryes for the car they have filled them with nitrogen, any reason why, ? only a fiver,
Title: Re: nitrogen tyres.
Post by: DryRob on 23 September 2013, 09:19:14 pm
No realworld benefit apparently...

http://www.theaa.com/motoring_advice/safety/filling-tyres-with-nitrogen.html
Title: Re: nitrogen tyres.
Post by: chaz on 24 September 2013, 12:33:03 am
mobile tyre fitters used to use nitrogen, easier than having a petrol compressor to inflate them
Title: Re: nitrogen tyres.
Post by: Farjo on 24 September 2013, 01:32:06 am
Perhaps tyres will end up with almost 100% nitrogen after a while and here's my theory. Buy a new tyre which is filled with normal air (78% nitrogen, 21% oxygen). Some of the oxygen permeates through the tyre so you re-inflate it with air. Assuming the tyre pressure went down by 10% the tyre is now filled with the original 78% Nitrogen and 21% Oxygen, minus the lost 10% oxygen, plus the replaced 7.8% Nitrogen and 2.1% Oxygen = 85.8% Nitrogen and 13.1% Oxygen.

Repeat several times and the proportion of Nitrogen will steadily rise, not to 100% but presumably into the high-90s%.
Title: Re: nitrogen tyres.
Post by: jon on 24 September 2013, 06:15:21 am
Why does only o2 permeate through the tyre, and not nitrogen?
Title: Re: nitrogen tyres.
Post by: positron on 24 September 2013, 06:48:03 am
Molecular size perhaps?
Title: Re: nitrogen tyres.
Post by: Lawrence on 24 September 2013, 12:21:42 pm
It's something to do with nitrogen expanding less with heat, so the pressure stays more constant.
 
It might make a difference in F1, but in a road car?  Probably not.
Title: Re: nitrogen tyres.
Post by: Jamieg285 on 24 September 2013, 12:36:55 pm
the wife,y bought some tryes for the car they have filled them with nitrogen, any reason why, ? only a fiver,


So that someone can make money for no real reason.
Title: Re: nitrogen tyres.
Post by: JZS 600 on 24 September 2013, 02:56:09 pm
I used to be a trimix diver, don't fill your tyres with helium  :lol
Title: Re: nitrogen tyres.
Post by: jon on 24 September 2013, 07:27:13 pm
Send her over here and I can replace the air for fresh for only a quid... probably needs doing weekly