Helium car tires

[NimrodTheGoat]

Overheard a conversation about car tires. One person said that instead of air they just use Nitrogen. Why use nitrogen, what is the difference? Could we therefore fill our car tires with helium to make them lighter, or even .... float? What challenges would a helium filled tire face?

Edited April 24, 2018 by NimrodTheGoat
more question

[Phi for All]

7 minutes ago, NimrodTheGoat said:

Overheard a conversation about car tires. One person said that instead of air they just use Nitrogen. Why use nitrogen, what is the difference? Could we therefore fill our car tires with helium to make them lighter, or even .... float? What challenges would a helium filled tire face?

Iirc, nitrogen has less problems with condensation, and it leaks less than oxygen. Helium will have problems staying inside the tires, and won't do much to decrease weight.

[koti]

3 hours ago, NimrodTheGoat said:

Overheard a conversation about car tires. One person said that instead of air they just use Nitrogen. Why use nitrogen, what is the difference? Could we therefore fill our car tires with helium to make them lighter, or even .... float? What challenges would a helium filled tire face?

The urban myth is that nitrogen is less susceptible to temperature changes therefore makes the wheel more stable at high speeds. Its costs around 20 bucks to fill your tires with nitrogen and lots of car lovers do it...and then brag about it. I guess less corosion and stability are real pluses but how much of that is actually noticible in real usage is unclear to me:

https://www.google.pl/amp/s/www.popularmechanics.com/cars/how-to/amp3894/4302788/

Edited April 24, 2018 by koti

[swansont]

6 hours ago, Phi for All said:

Iirc, nitrogen has less problems with condensation, and it leaks less than oxygen. Helium will have problems staying inside the tires, and won't do much to decrease weight.

Condensation is water, so I don't see how nitrogen vs oxygen solves that. That's the wrong way to frame it. If you're worried about water, then it's a matter of taking air (which has water in it) and running it through a compressor vs a dry gas, and nitrogen is the cheapest one of those. 

As far as leaking, it's actually diffusion through the material. Oxygen diffuses 3-4 times faster, according to this NIST pub.  

Personally I use a ~80/20 mix and I'm fine with that.

[DrP]

9 minutes ago, swansont said:

nitrogen is the cheapest one of those. 

As far as leaking, it's actually diffusion through the material. Oxygen diffuses 3-4 times faster, according to this NIST pub.  

Personally I use a ~80/20 mix and I'm fine with that.

Wouldn't something like Xenon gas be better for that? Bigger molecule so probably wont leak. Nice and dense. Probably too expensive though so nothing wrong with nitrogen/air.

[swansont]

13 minutes ago, DrP said:

Wouldn't something like Xenon gas be better for that? Bigger molecule so probably wont leak. Nice and dense. Probably too expensive though so nothing wrong with nitrogen/air.

Possibly, and if so, expense is likely why it isn't generally* done. They didn't test Xenon in the link I provided, but they did test Argon, and it was worse than Nitrogen. Noble gases are monoatomic, which probably aids in diffusion

 

*I wouldn't be surprised if there were a few folks who have tried it.

[Scott of the Antares]

As you guys have mentioned, nitrogen reduces the rate of gas leaking compared to air. Benefits include less maintenance (apparently air leaks out 3 to 4 times quicker than nitrogen).

The US military, commercial airlines & NASA use nitrogen to reduce the freezing of any water held in the air of their tyres.

[StringJunky]

1 hour ago, Scott of the Antares said:

As you guys have mentioned, nitrogen reduces the rate of gas leaking compared to air. Benefits include less maintenance (apparently air leaks out 3 to 4 times quicker than nitrogen).

The US military, commercial airlines & NASA use nitrogen to reduce the freezing of any water held in the air of their tyres.

They use it to reduce the risk of fire at high altitude because the wheels are stored in the wings next to fuel tanks.

[Scott of the Antares]

1 hour ago, StringJunky said:

They use it to reduce the risk of fire at high altitude because the wheels are stored in the wings next to fuel tanks.

 

A great point! Thank you sir!

[Bender]

Using air requires me to pump my tires about twice a year, an inconvenience I can overcome.

Sounds like people using gold plated wires for their audio or ceramic bearings in their bike: sounds fancy, you can brag about the money you spent on it, but it hardly makes a difference.     

[StringJunky]

6 minutes ago, Bender said:

Using air requires me to pump my tires about twice a year, an inconvenience I can overcome.

Sounds like people using gold plated wires for their audio or ceramic bearings in their bike: sounds fancy, you can brag about the money you spent on it, but it hardly makes a difference.     

That last 1% doesn't matter to the masses but to the discerning aficionado it does. .. it can mean the difference between winning and losing or something being tolerable or not. Goldplating stops oxidation,it's not just about signal purity.

[MigL]

Nitrogen seems to have less pressure variation with temperature.
If you have tire pressure sensors on your vehicle, your manual will recommend the use of nitrogen.

[Bender]

21 hours ago, StringJunky said:

That last 1% doesn't matter to the masses but to the discerning aficionado it does. .. it can mean the difference between winning and losing or something being tolerable or not. Goldplating stops oxidation,it's not just about signal purity.

Ideal gasses all react exactly the same way to temperature variation. In what way does either nitrogen or air deviate enough from that to be significant?

Perhaps the increased leakage is the reason for that advice.

21 hours ago, StringJunky said:

That last 1% doesn't matter to the masses but to the discerning aficionado it does. .. it can mean the difference between winning and losing or something being tolerable or not. Goldplating stops oxidation,it's not just about signal purity.

Yes, there is a subgroup of those who spend the additional money for whom it actually makes a difference. The point is that it is not because people spend money on something that it actually makes sense (for them).  

[John Cuthber]

20 hours ago, MigL said:

Nitrogen seems to have less pressure variation with temperature.
If you have tire pressure sensors on your vehicle, your manual will recommend the use of nitrogen.

In addition to the point already made about ideal gas behaviour, I rather suspect that much of the pressure variation is due to changes in the elasticity of the rubber with temperature.

(Obviously the weight of the vehicle will also affect it.
Unless you check the tyre pressure every time you add goods or passengers to the car...

[MigL]

No gas is an ideal gas, and, more importantly, most all N2 sources are dried, while air may not be.

The GM recommendation for a Cadillac CTS-V with TPMS is N2 for the following reasons

-A reduction in the loss of tire pressure over time.
-A reduction in the variance of tire pressures with temperature changes due to reduction of water vapor concentration.
-A reduction of long-term rubber degradation due to a drop in oxygen.

I'm sure other hi-performance vehicles with tire pressure monitoring systems do the same.

[J.C.MacSwell]

On 4/24/2018 at 7:09 AM, swansont said:

Personally I use a ~80/20 mix and I'm fine with that.

I have to admit that made me laugh

[koti]

15 hours ago, J.C.MacSwell said:

I have to admit that made me laugh

Unless its a 918 spyder or similar type of hyper car and swansont takes it for a spin at 200 mph - then it would make a difference.

Edited April 26, 2018 by koti

[John Cuthber]

16 hours ago, MigL said:

No gas is an ideal gas, and, more importantly, most all N2 sources are dried, while air may not be.

The GM recommendation for a Cadillac CTS-V with TPMS is N2 for the following reasons

-A reduction in the loss of tire pressure over time.
-A reduction in the variance of tire pressures with temperature changes due to reduction of water vapor concentration.
-A reduction of long-term rubber degradation due to a drop in oxygen.

I'm sure other hi-performance vehicles with tire pressure monitoring systems do the same.

Nitrogen and oxygen are pretty close to ideal at the sort of pressures you get in car tyres; the differences from ideal would be small. The difference between their departures from ideality are even smaller.

 

Unless there's liquid water in the tyre, the vapour pressure of water is irrelevant.

If there is liquid water in the tyre someone has screwed up so badly that  the point is moot.

 

I suspect that oxygen diffuses through rubber a bit faster than nitrogen does. So you may need to re inflate your tyres more often if you use air.

I doubt the effect is as big as doubling the  re-inflation frequency. If it did then you would need to compare the cost  of two air fillings vs 1 nitrogen filling.

In my (very limited) experience air is free and nitrogen is charged for. I guess it comes down to the value you put on your time.

 

 

The extent to which this makes a difference is questionable.

Tyres have a "correct" pressure, but altering the vehicle loading will change the actual pressure.

Does GM run a garage franchise?
Do those garages sell nitrogen?

[Bender]

44 minutes ago, John Cuthber said:

Tyres have a "correct" pressure, but altering the vehicle loading will change the actual pressure.

Actually, the load-dependance of the tire pressure is pretty small. It is the contact area with the ground which is roughly proportional to the load. The volume of the tire, which is inversely proportional to the pressure, changes much less; certainly less than the accuracy of the average manometer.

[J.C.MacSwell]

1 hour ago, koti said:

Unless its a 918 spyder or similar type of hyper car and swansont takes it for a spin at 200 mph - then it would make a difference.

I think we can trust swansont to air on the safe side.

[Phi for All]

2 hours ago, koti said:

Unless its a 918 spyder or similar type of hyper car and swansont takes it for a spin at 200 mph - then it would make a difference.

I heard swansont drives a brand new Heisenberg, and it doesn't even have a speedometer, for uncertain reasons. 

[MigL]

No way...
Aston Martin DB5
James Bond wouldn't drive anything else !

 

Don't forget I live in Canada John, liquid water in my tires are a definite possibility at -25 deg C.
And those cold winter mornings are when your dash screen would tell you your tire pressure is low; even if you just checked them the previous day.
Oh, and I have an adaptor to fill my tires at work ( for free ).

But you're right, I probably wouldn't bother if it wasn't free.

Edited April 26, 2018 by MigL

[koti]

1 hour ago, Phi for All said:

I heard swansont drives a brand new Heisenberg, and it doesn't even have a speedometer, for uncertain reasons. 

It's in his garage until he takes a look at it and poof! (I have dreams like that)

1 hour ago, MigL said:

No way...
Aston Martin DB5
James Bond wouldn't drive anything else !

 

Don't forget I live in Canada John, liquid water in my tires are a definite possibility at -25 deg C.
And those cold winter mornings are when your dash screen would tell you your tire pressure is low; even if you just checked them the previous day.
Oh, and I have an adaptor to fill my tires at work ( for free ).

But you're right, I probably wouldn't bother if it wasn't free.

If Bond was real he'd be buddies with Baron Christian Erland Harald von Koenigsegg:
https://www.koenigsegg.com/

[Endy0816]

On 4/26/2018 at 5:26 PM, MigL said:

Don't forget I live in Canada John, liquid water in my tires are a definite possibility at -25 deg C.
And those cold winter mornings are when your dash screen would tell you your tire pressure is low; even if you just checked them the previous day.

Likely Gay-Lussac's law in action.

Pressure dropping with the temperature.

[John Cuthber]

On 4/26/2018 at 10:26 PM, MigL said:

liquid water in my tires are a definite possibility at -25 deg C.

Bollocks.

25 degrees below the freezing point is not a good place to look for a liquid.

Why on earth did you post that on a science web site?

On 4/26/2018 at 10:26 PM, MigL said:

And those cold winter mornings are when your dash screen would tell you your tire pressure is low; even if you just checked them the previous day.

Does it say "but you would be fine if it was nitrogen"?

If not the point's irrelevant

On 4/26/2018 at 10:26 PM, MigL said:

But you're right,

Sometimes, deliberately selective quotes are the best option available.