Tires: Air vs Nitrogen

[mooniac15u]

Just now, EricJ said:

Any thoughts on why high-temp apps tend to use N2 in tires?     One thought I've heard is it's easier to keep N2 dry, but I don't know if that's even the motivator.

I could guess but it probably wouldn't be any better than your guess. I have a Ph.D. In chemistry so I can discuss ideal gas behavior all day but my expertise is mostly theoretical. Maybe one of the engineers around here can comment on the real world application. 

[EricJ]

Just now, mooniac15u said:

I could guess but it probably wouldn't be any better than your guess. I have a Ph.D. In chemistry so I can discuss ideal gas behavior all day but my expertise is mostly theoretical. Maybe one of the engineers around here can comment on the real world application. 

I have an advanced degree in engineering, and I've done as much damage on this as I can do. 

[mike_elliott]

2 hours ago, EricJ said:

For CB racers that store their race tires inflated, the O2 migration (from the inside to the outside) will slowly harden the rubber compound of the tire (which results in less grip). 

These are the back markers in any class of racing now days.

[carusoam]

Slow poke = back marker...

The guys that are a few laps down.  

Guys on the lead lap have to go around the back markers a couple of times each race. Coming up on a back marker can be a bit of a hazard, because of the difference in speed. The slower the back marker, the more often the leaders run up on it....

really tough on a road course where it can be difficult for the back marker to avoid the fray by staying away from the racing line...

The shorter the track, the more frequent the hazard becomes...

 

Oxygen transportation through a tire, making the rubber compound harder... I would have to look that one up. Oxidation of rubber compounds?

Good grip of a Tire usually comes with a soft rubber compound. Soft compounds tend to wear easily.

 

 

PP thoughts only. A big fan of auto racing back in the day...

Best regards,

-a-

[RobertGary1]

On 10/19/2017 at 5:47 PM, Mooneymite said:

I was looking at new cars a year ago and noticed that "nitrogen filled tires" was the latest dealer add on.  Anywhere from $75 to $125 dealer charge.....yeah, right!  I wonder who is going to check and see if those tires are really filled with 100% Nitrogen, or just 78%.  

Costco fills  my tires with nitrogen for free. 

-Robert

[RobertGary1]

On 10/20/2017 at 6:08 PM, mooniac15u said:

I could guess but it probably wouldn't be any better than your guess. I have a Ph.D. In chemistry so I can discuss ideal gas behavior all day but my expertise is mostly theoretical. Maybe one of the engineers around here can comment on the real world application. 

Bigest  advantages of nitrogen is just that pressure changes less with temperature than air. You don’t have to change pressure seasonally etc

-Robert 

Edited October 27, 2017 by RobertGary1

[Jerry 5TJ]

On 10/20/2017 at 9:13 PM, EricJ said:

I have an advanced degree in engineering, and I've done as much damage on this as I can do. 

I too have advanced degrees in engineering & I use Nitrogen in my tires because I like the green tire stem caps.  

[mooniac15u]

7 hours ago, RobertGary1 said:

Bigest  advantages of nitrogen is just that pressure changes less with temperature than air. You don’t have to change pressure seasonally etc

-Robert 

The pressure of Nitrogen, Oxygen, and regular air all exhibit nearly identical behavior with changes in temperature.  The compressibility factors of Nitrogen and Oxygen at 70 degrees F and 1 atm are 0.9998 and 0.9993 respectively.  The changes in pressure of any of these gases or mixtures will vary with temperature according to the ideal gas law (PV=nRT). A tire pressure gauge would not be precise enough to measure the difference in pressure changes between Nitrogen and air over seasonal temperature differences.

[Hank]

1 hour ago, Jerry 5TJ said:

I too have advanced degrees in engineering & I use Nitrogen in my tires because I like the green tire stem caps.  

Hey, I've got those on my truck! And when I need to, I add air from the compressor in my garage. Never knew why my caps were green, thought it was just the place I bought the tires from after I moved.

--Pilot Hank, BSME, MSE

[bradp]

9 hours ago, RobertGary1 said:

Costco fills  my tires with nitrogen for free. 

I find marking my mooney at Costco is too much of a pain.  

 

i thought  there was a benefit for high speed aircraft in the setting of a blow out in limiting oxygen availability to overheating brakes ?

[clh]

2 hours ago, Jerry 5TJ said:

I too have advanced degrees in engineering & I use Nitrogen in my tires because I like the green tire stem caps.  

Finally, we have a good reason to use pure nitrogen....

[RobertGary1]

2 hours ago, mooniac15u said:

The pressure of Nitrogen, Oxygen, and regular air all exhibit nearly identical behavior with changes in temperature.  The compressibility factors of Nitrogen and Oxygen at 70 degrees F and 1 atm are 0.9998 and 0.9993 respectively.  The changes in pressure of any of these gases or mixtures will vary with temperature according to the ideal gas law (PV=nRT). A tire pressure gauge would not be precise enough to measure the difference in pressure changes between Nitrogen and air over seasonal temperature differences.

This is a good article that goes into more detail “With nitrogen, your tire pressures will remain more constant, saving you a small amount in fuel and tire-maintenance costs.” http://www.popularmechanics.com/cars/how-to/a3894/4302788/

 

or 

“Nitrogen-filled tires are less susceptible to temperature swings, so the tires are more likely to maintain constant pressure under a wide variety of temperatures and vehicle speeds,” says Ed Kim, vice president of industry analysis at automotive research firm AutoPacific. “Part of this is due to the intrinsic qualities of nitrogen over air, but part of this is also because air has water vapor in it (humidity), and humid air is also more susceptible to pressure changes as a result of temperature”

https://cars.usnews.com/cars-trucks/best-cars-blog/2016/12/nitrogen-in-tires-do-you-need-it

 

[mooniac15u]

6 minutes ago, RobertGary1 said:

This is a good article that goes into more detail “With nitrogen, your tire pressures will remain more constant, saving you a small amount in fuel and tire-maintenance costs.” http://www.popularmechanics.com/cars/how-to/a3894/4302788/

 

or 

“Nitrogen-filled tires are less susceptible to temperature swings, so the tires are more likely to maintain constant pressure under a wide variety of temperatures and vehicle speeds,” says Ed Kim, vice president of industry analysis at automotive research firm AutoPacific. “Part of this is due to the intrinsic qualities of nitrogen over air, but part of this is also because air has water vapor in it (humidity), and humid air is also more susceptible to pressure changes as a result of temperature”

https://cars.usnews.com/cars-trucks/best-cars-blog/2016/12/nitrogen-in-tires-do-you-need-it

 

Water vapor, yes. Nitrogen, no. Anyone who claims otherwise has an incorrect understanding of the physics of gases. 

[RobertGary1]

1 hour ago, mooniac15u said:

Water vapor, yes. Nitrogen, no. Anyone who claims otherwise has an incorrect understanding of the physics of gases. 

I suppose I just always assume when you say "air" that includes common levels of humidity. I suppose you could dry the air before you put it in the tire but its cheaper to use Nitrogen. Personally I've enjoyed having Nitrogen in my car tires because I don't have to add air when the season changes.

-Robert

[mooniac15u]

26 minutes ago, RobertGary1 said:

I suppose I just always assume when you say "air" that includes common levels of humidity. I suppose you could dry the air before you put it in the tire but its cheaper to use Nitrogen. Personally I've enjoyed having Nitrogen in my car tires because I don't have to add air when the season changes.

-Robert

You must not live somewhere with significant seasonal changes.  Nitrogen pressure in your tires will change about 1 psi for every 10 deg F change in temperature.

[EricJ]

1 hour ago, mooniac15u said:

Water vapor, yes. Nitrogen, no. Anyone who claims otherwise has an incorrect understanding of the physics of gases. 

I think that's what it comes down to.    Looking around at it a little more N2 won't combine with any free H like O will to make water, which is a big contributor to complicating pressure control.   It's easier to keep N2 dry.    Besides living in AZ, I have a drier on my compressor, so so I've never bothered with N2 in tires other than the usual 78% blend.

[mooniac15u]

Just now, EricJ said:

I think that's what it comes down to.    Looking around at it a little more N2 won't combine with any free H like O will to make water, which is a big contributor to complicating pressure control.   It's easier to keep N2 dry.    Besides living in AZ, I have a drier on my compressor, so so I've never bothered with N2 in tires other than the usual 78% blend.

Hydrogen and Oxygen will not normally spontaneously combine to make water.  That would require combustion inside your tire.

Water vapor already present in the air complicates things because it can change state in the temperature and pressure ranges we are talking about.  That changes the amount of gas present in the tire which will impact the pressure.

[Captnmack]

I use Helium, it make for quicker and higher flights...