Nitrogen?

[Mean_Green]

Thinking about getting new paws next spring. What is the typical cost to do all four (five?) with Nitrogen? Can you add normal air later?

Is there a reason NOT to?

 

[Eman85]

Do a google for the percentage of nitrogen in the air we breathe. I'd say the only benefit or pure nitrogen is clean and dry air. Spend the money on a good tire pressure gauge and keep them inflated, that kills tires more than "normal" air.

 

[Joseph Garcia]

If you like to spend money for no good reason, go ahead and purchase the nitrogen fills. Otherwise, it is a complete waste of money. As indicated above by @Eman85, the air that we breath and what normally fills tires is already 78% nitrogen, and an additional 22% is not going to make any difference whatsoever for non-racing applications (not sure that it would even make a difference there either).

Note that some shops have better drying and filtration equipment than others on their compressed air systems, and it probably makes sense to get as close to clean and dry air as practical.

 

[PPV_2018]

“Pure” (read: straight, as not even UHP Nitrogen is 100% pure — there will always be impurities in the gases) Nitrogen is lighter than atmospheric air (which is already over 3/4 nitrogen already), and due to it’s chemical makeup, may keep a tire inflated for longer versus atmospheric air. Despite misinformation, when a tire is filled with “straight” nitrogen, it has less resistance from friction versus atmospheric air. The result is a marginally better and often negligible benefit in gas mileage and perhaps tire life.

Nitrogen is inert, you can add it to air; you can add air to nitrogen, or have any mixture percentage of the two in a tire at any given time. Obviously, you will not receive the marginal benefit of n2 in the tires if it’s being cut with atmospheric air anyways.

I’ve done my own calculations and over a lifetime, a home rig of n2 costs far less than filling up w/ air at gas stations. Actual results may vary depending on more factors that can be listed here. The cost for a home rig is cheap once you get the initial investment out the way.

Here’s mine:



Bottom line: any reason NOT to do it? No. But if you’re expecting nitrogen to be some sort elixir that will improve gas mileage tenfold, you will be disappointed.

 

[wjburken]

Thinking about getting new paws next spring. What is the typical cost to do all four (five?) with Nitrogen? Can you add normal air later?

Is there a reason NOT to?

No mechanical or harmful reason to NOT do it.

You can add air to nitrogen filled tires, just like you can add nitrogen to air filled tires.

That being said, you will never be able to get pure nitrogen in your tire unless you have a way to draw a vacuum and remove all of the air that is trapped in the tire when it is mounted. The trapped air (at atmospheric pressure) amounts to roughly 35% of the total volume (25% of which is not nitrogen) of a tire inflated to 40psi assuming 255/50R20 tires which have a volume of just under 4000in^3. This leaves roughly 9% of the gas in the tire being not nitrogen. That is if my understanding of the Ideal Gas Law is correct, but it is the Saturday after thanksgiving and I’ve only had one cup of coffee.

 

[Joseph Garcia]

“Pure” (read: straight, as not even UHP Nitrogen is 100% pure — there will always be impurities in the gases) Nitrogen is lighter than atmospheric air (which is already over 3/4 nitrogen already), and due to it’s chemical makeup, may keep a tire inflated for longer versus atmospheric air. Despite misinformation, when a tire is filled with “straight” nitrogen, it has less resistance from friction versus atmospheric air. The result is a marginally better and often negligible benefit in gas mileage and perhaps tire life.

Nitrogen is inert, you can add it to air; you can add air to nitrogen, or have any mixture percentage of the two in a tire at any given time. Obviously, you will not receive the marginal benefit of n2 in the tires if it’s being cut with atmospheric air anyways.

I’ve done my own calculations and over a lifetime, a home rig of n2 costs far less than filling up w/ air at gas stations. Actual results may vary depending on more factors that can be listed here. The cost for a home rig is cheap once you get the initial investment out the way.

Here’s mine:

View attachment 443791

Bottom line: any reason NOT to do it? No. But if you’re expecting nitrogen to be some sort elixir that will improve gas mileage tenfold, you will be disappointed.

Unless you are purchasing hospital grade compressed nitrogen, it is really not all that 'pure'. I used compressed gas custom mixes of nitrogen and oxygen for years while doing deep decompression wreck diving, and the difference in purity between hospital grade nitrogen and commercial nitrogen (and oxygen) was very significant. I know, we are talking about filling tires, and not a breathing gas here, but I did want to make this point about compressed gas purity standards.

Adding to @wjburken comments above, IMO, the weight difference between 100% nitrogen and compressed air is minimal, since the other major element in compressed air is oxygen, which is only 1 element higher and only 2 atomic units heavier on the Periodic Table, and that difference gets further reduced by the gas composition ratios, which nets you a 3% weight reduction by converting to 100% nitrogen. Yes, 3% is larger that 0%, but I think I'd be hard pressed to notice any significant difference between the two.

 

[homesick]

From what I've read, the only real advantage of nitrogen is for pro racers. It's supposed to be less prone to pressure fluctuations caused by heat.

joe