I noticed in Kwik-Fit the option of having tyres filled with nitrogen instead of plain old air for £1 per wheel.

Am I missing something?

If not air, why not helium to make the unsprung weight lighter??

From this you may tell I am not a science expert, but HUH  :-?

cruisetopoland wrote on 04. Dec 2009 at 16:27:

I noticed in Kwik-Fit the option of having tyres filled with nitrogen instead of plain old air for £1 per wheel. Am I missing something? If not air, why not helium to make the unsprung weight lighter?? From this you may tell I am not a science expert, but HUH  :-?

Because your tyres would squeek :D

There were posting on this about 2 months ago.I think the conclusion was there was nothing to gain on a normal road car.

Dry nitrogen as they advertise it ( and there is no such thing as wet nitrogen !!!) is what is used to inflate aircraft tyres. It has some advantages in that ...

Pure nitrogen contains no moisture, so is hardly affected by temperature at all, it is the water vapour that is affected by temperature. Now aircraft tyres go from -44 C at altitude to around +160 C at the end of the landing (braking) run ... so are badly affected .....  your car does not, I believe, operate in such extremes.

Nitrogen molecules are the largest in the gases that constitute "air" ... it is believed that tyres with pure nitrogen hold pressure better as the molecules don't "leak" out through the permability of the tyre.

If, BIG IF, you decide to go the nitrogen route, you must then ONLY EVER check/top up with nitrogen .. or you have just undone all the so called benefits.

Even a small amount of water vapour can make a big difference ... if you think about it .. most folks will say they have to adjust their tyres less in the summer than the winter ... in the summer the air is drier .. :)


HTH

Entwood wrote on 04. Dec 2009 at 16:36:

Dry nitrogen as they advertise it ( and there is no such thing as wet nitrogen !!!) is what is used to inflate aircraft tyres. It has some advantages in that ... Pure nitrogen contains no moisture, so is hardly affected by temperature at all, it is the water vapour that is affected by temperature. Now aircraft tyres go from -44 C at altitude to around +160 C at the end of the landing (braking) run ... so are badly affected .....  your car does not, I believe, operate in such extremes. Nitrogen molecules are the largest in the gases that constitute "air" ... it is believed that tyres with pure nitrogen hold pressure better as the molecules don't "leak" out through the permability of the tyre. If, BIG IF, you decide to go the nitrogen route, you must then ONLY EVER check/top up with nitrogen .. or you have just undone all the so called benefits. Even a small amount of water vapour can make a big difference ... if you think about it .. most folks will say they have to adjust their tyres less in the summer than the winter ... in the summer the air is drier .. :) HTH

Nice answer  ;)

Just searched helium in tyres on google and found that weight saving less than material needed to keep helium in...

cruisetopoland wrote on 04. Dec 2009 at 16:44:

Entwood wrote on 04. Dec 2009 at 16:36: Dry nitrogen as they advertise it ( and there is no such thing as wet nitrogen !!!) is what is used to inflate aircraft tyres. It has some advantages in that ... Pure nitrogen contains no moisture, so is hardly affected by temperature at all, it is the water vapour that is affected by temperature. Now aircraft tyres go from -44 C at altitude to around +160 C at the end of the landing (braking) run ... so are badly affected .....  your car does not, I believe, operate in such extremes. Nitrogen molecules are the largest in the gases that constitute "air" ... it is believed that tyres with pure nitrogen hold pressure better as the molecules don't "leak" out through the permability of the tyre. If, BIG IF, you decide to go the nitrogen route, you must then ONLY EVER check/top up with nitrogen .. or you have just undone all the so called benefits. Even a small amount of water vapour can make a big difference ... if you think about it .. most folks will say they have to adjust their tyres less in the summer than the winter ... in the summer the air is drier .. :) HTH Nice answer  ;) Just searched helium in tyres on google and found that weight saving less than material needed to keep helium in...

Yes -- the helium molecule is a wee little beasty and can get out through most membranes !

Entwood wrote on 04. Dec 2009 at 16:36:

Dry nitrogen as they advertise it ( and there is no such thing as wet nitrogen !!!) is what is used to inflate aircraft tyres. It has some advantages in that ... Pure nitrogen contains no moisture, so is hardly affected by temperature at all, it is the water vapour that is affected by temperature. Now aircrafttyres go from -44 C at altitude to around +160 C at the end of the landing (braking) run ... so are badly affected .....  your car does not, I believe, operate in such extremes. Nitrogen molecules are the largest in the gases that constitute "air" ... it is believed that tyres with pure nitrogen hold pressure better as the molecules don't "leak" out through the permability of the tyre. If, BIG IF, you decide to go the nitrogen route, you must then ONLY EVER check/top up with nitrogen .. or you have just undone all the so called benefits. Even a small amount of water vapour can make a big difference ... if you think about it .. most folks will say they have to adjust their tyres less in the summer than the winter ... in the summer the air is drier .. :) HTH

My Mig does  ;D ;D ;D ;D ;D ;D ;D ;D ;D

i am actually wondering about trying it. Currently running sports contact 3's, and have noticed they seem quite sensative to pressure. 34 or over they give a very hard ride, and 31 ish or below they go a bit hot and squidgy.
Add in the fact 2 of the 4 seem to leak down a fraction more than i would like, meaning a week and a half of unchecked pressure can see 27 on the gauge and a ware line on the edge that looks like i've been on a track day. Not good as i've not been caining it.
I did wonder it bigger molecules would be a good idea?

Excuse my ignorance on this but, how do they fill the tyre with just nitrogen ? I mean do they have to use a vac pump first to get all the "air" out.

Sorry for my ignorance, it is just that we use nitrogen at work and I could get it for free, but I assume there must be more to it than just releasing the air in the tyre under pressure and then refilling it.  :-/

Mantahatch wrote on 04. Dec 2009 at 19:30:

Excuse my ignorance on this but, how do they fill the tyre with just nitrogen ? I mean do they have to use a vac pump first to get all the "air" out. Sorry for my ignorance, it is just that we use nitrogen at work and I could get it for free, but I assume there must be more to it than just releasing the air in the tyre under pressure and then refilling it.  :-/

Not sure how they do it to be honest we used to have a compressor with a special membrane in it to remove nitrogen from air in order to give it a higher oxygen content for scuba diving. May work on the reverese principal.

But as you said do they 'Suck Out' the air thats already in to give 100% Nitrogen or is it partially blended to a high nitrogen content.

I would imagine that kwik crap would just top up the tyre with nitrogen not as you would expect them to do and compleatly purge the tyre of air as should be done. Sounds like a few drops of snake oil to me :-/

Tony H wrote on 05. Dec 2009 at 00:16:

I would imagine that kwik crap would just top up the tyre with nitrogen not as you would expect them to do and compleatly purge the tyre of air as should be done. Sounds like a few drops of snake oil to me :-/

Snake oil and filter was £34.99  ;D