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While getting my oil changed this morning at Jeep they said they recommend people to start putting Nitrogen in the tires instead of regular air for better gas mileage etc. Anyone have any information about putting Nitrogen in the tires? Did a search and could not find anything about this.
 

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I have heard of lots of places doing Nitrogen inflation but I don't know the advantage to it. Maybe it is lighter than air? or maybe it helps preserve the rubber from the inside out?
 

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Every car we get from the factories here has the air let out and Nitrogen put in. The nitrogen molecule is larger than a regular air molecule and does not escape through the rubber as easily. It also does not expand after warming up like air does and helps to keep the tires cool and under proper inflation.
 

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I will try to keep this short and understandable,

Nitrogen is a good substitute for air only in specific situations.
Generally it is used in racing applications because the pressure won't rise when the tire is at operating temp.
So, if the right front is best at 37.3 psi and the left front is best at 34.7 psi etc. you can set those pressures at the start of a race and they will not change.
This way, the car will handle as anticipated once the rubber is up to temperature and not change as the tire gets hotter.
However, it is a LOUSY way for service shops to make money.
A street vehicle has a cold tire pressure specification, and for this discussion, lets use 35 psi as cold pressure.
Remember to check pressure monthly as cold means ambient temp.
Anyways, the tire maker has determined that by setting the correct cold pressure, the tire pressure will increase as the tire reaches operating temp.
Air in the tire will increase 1psi for every seven degrees above ambient.
So, we begin our trip at 80 degrees and our 35 psi ambient tire is operating at about 150 degrees in 15 minutes.
OK lets see what goes on here: Since the temp has increased by 70 degrees we divide that by 7 which means our operating pressure has increased to 45 psi.
This is anticipated by the tire manufacturer and is the pressure that will provide the best handling and tread life for this application at that ambient temp.
Now, if we were to have nitrogen in the tire our starting pressure and our operating pressure will not change.
Not good, we will actually be operating underinflated at 35 psi hot.
This will actually cause the tire to run hotter due to increased carcass flexing and will actually cause increased wear because the tread rubber will be softer due to that heat.
So, once you cut through the hype, you see it is a scam against the uninformed.
Quite simply, good for racing application, bad for daily application.
Questions?

Rob
 

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that gave me tired head!
Too much nitrogen and not enough oxygen. ;)

Air is a mixture of gases - 78% nitrogen and 21% oxygen - with traces of water vapor, carbon dioxide, argon, and various other components.

Hmm. So if the smaller molecules leak out faster, then eventually your nitrogen content will go up in the tires as you add air to repressurize.
Which is bad because it won't warm up enough to gain appropriate pressure. Maybe I better go out and change the air in my tires.:rofl:
 

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I had this service tech years ago working for me, his van had a flat so he decides to inflate tire with freon. He got a few miles down the round until tire exploded.
 

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When I was in the service department at the dealer a few weeks ago they had a display promoting nitrogen for your tires. The cost was about $49.00 as I recall and they were giving away a free road service program of some type with it.
 

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I had this service tech years ago working for me, his van had a flat so he decides to inflate tire with freon. He got a few miles down the round until tire exploded.
WOW.........:icon_confused:
 

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What exactly is the "cold" temp that manufacturers expect you to fill at? 80? This winter I filled to about 37psi (tires rated at 44), and now when I cruise down the interstate they hit 45+psi. How much over the rating is too much?
 

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Some info from tirerack.com:

Advantages of Correct Tire Inflation

Maintaining correct tire inflation pressure helps optimize tire performance and fuel economy. Correct tire inflation pressure allows drivers to experience tire comfort, durability and performance designed to match the needs of their vehicles. Tire deflection (the tread and sidewall flexing where the tread comes into contact with the road) will remain as originally designed and excessive sidewall flexing and tread squirm will be avoided. Heat buildup will be managed and rolling resistance will be appropriate. Proper tire inflation pressure also stabilizes the tire's structure, blending the tire's responsiveness, traction and handling.

Can you easily identify which tire is 30% underinflated? Here is what they would look like in the morning parked in your garage.
(Roll your mouse across the pictures to find out if you were right.)



Tough to tell; isn't it? Tire pressure must be checked with a quality air gauge as the inflation pressure cannot be accurately estimated through visual inspection.


Disadvantages of Underinflation

An underinflated tire can't maintain its shape and becomes flatter than intended while in contact with the road. If a vehicle's tires are underinflated by only 6 psi it could weaken the tire's internal structure and eventually lead to tire failure. Lower inflation pressures will allow more deflection as the tire rolls. This will build up more internal heat, increase rolling resistance (causing a reduction in fuel economy of up to 5%) and reduce the tire's tread life by as much as 25% while increasing the probability of irregular treadwear. Drivers would also find a noteworthy loss of steering precision and cornering stability. While 6 psi doesn't seem excessively low, it typically represents about 20% of a passenger car tire's recommended pressure.

Disadvantages of Overinflation

An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when encountering potholes or debris in the road, as well as experience irregular tread wear. Higher inflated tires cannot isolate road irregularities as well causing the vehicle to ride harsher and transmit more noise into its interior. However, higher inflation pressures reduce rolling resistance slightly and typically provide a slight improvement in steering response and cornering stability. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures.
 

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This floats around RV forums quite a bit. It's mostly an easy way to scam RV'ers out of $50 a tire when we're dealing with bus sized 22.5 wheels.

Yes, it works great on race cars where the tire goes from ambient to 200 degrees, so it doesn't change the shape much compared to normal air. At least the NASCAR tire pressure won't change that 3% or 4% from one temp to another. :D

It's mostly a waste of time due to Boyle's laws since common air in the atmosphere is mostly nitrogen in the first place. The advantage of other gasses not leaking away due to the molecular size of nitrogen is hardly enough to justify the cost IMHO. And what would happen at the very worst when you don't check your tire pressure for six years? :) The other gasses might leak off, leaving the 80% or so nitrogen that was there in the first place, so you have a slightly low tire.
 

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I had this service tech years ago working for me, his van had a flat so he decides to inflate tire with freon. He got a few miles down the round until tire exploded.
Holy crap?!? It's a good thing he didn't fill it with propane!! :rofl:

The problem with Freon is its pressure changes with temp... after all, it is a REFRIGERANT?!? Freon at low pressure absorbs heat, and high pressure in the condenser dumps that heat. No matter what though, Freon isn't going to be contained very well in a tire anyway since it likes sitting at 100+ PSI in a tank depending on R12, R22, R134a etc. at room temp. It's a wonder the tire made it that far.
 

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What exactly is the "cold" temp that manufacturers expect you to fill at? 80? This winter I filled to about 37psi (tires rated at 44), and now when I cruise down the interstate they hit 45+psi. How much over the rating is too much?
Hi Polar,
As I said in my long winded response, the cold pressure (as stated on the door sticker) is the beginning tire pressure at the start of the day.
So, whether it is 30 degrees or 80 degrees, the beginning pressure is per the door label.
If you re-read my response you'll see I refer to ambient temperature so as not to cause confusion.
I did find however, during the winter when the temp falls to 10 below and I was at 35 p.s.i. at 30 degrees above the day before, the pressure sensors would see the low pressure till the tire warmed.
Like you, I kept them at 37/38 p.s.i. to keep the TPMS from annoying me.

Now, since your tires have a 44 psi maximum cold pressure stated on the sidewall, the manufacturer has designed that tire to operate at the elevated pressure that occurs while driving.
You aren't hurting a thing, you just have high load rated tires.

Rob
 

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Also if you do any off road driving and you are airing down and back up at the end of your ride then nitrogen would be a waste of time & money.
 

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Hi Polar,
As I said in my long winded response, the cold pressure (as stated on the door sticker) is the beginning tire pressure at the start of the day.
So, whether it is 30 degrees or 80 degrees, the beginning pressure is per the door label.
If you re-read my response you'll see I refer to ambient temperature so as not to cause confusion.
I did find however, during the winter when the temp falls to 10 below and I was at 35 p.s.i. at 30 degrees above the day before, the pressure sensors would see the low pressure till the tire warmed.
Like you, I kept them at 37/38 p.s.i. to keep the TPMS from annoying me.

Now, since your tires have a 44 psi maximum cold pressure stated on the sidewall, the manufacturer has designed that tire to operate at the elevated pressure that occurs while driving.
You aren't hurting a thing, you just have high load rated tires.

Rob
So, I could safely inflate my tires to 44psi before I go on a trip and not worry if they went up 5 or more psi?
 

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Another advantage to using the nitrogen is that it is dry. This helps to reduce dry rot from the inside. Dried compressed air would be good too.

I use nitrogen in my slicks and my winter tires, as it also doesn't lose pressure when the temp drops like regular air does. Full disclosure: I haven't paid for any nitrogen yet - A guy I used to work with has a sponsorship (stock car team) and gave me his extra cylinder. I call him when it's empty.
 

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Another advantage to using the nitrogen is that it is dry. This helps to reduce dry rot from the inside. Dried compressed air would be good too.

I use nitrogen in my slicks and my winter tires, as it also doesn't lose pressure when the temp drops like regular air does. Full disclosure: I haven't paid for any nitrogen yet - A guy I used to work with has a sponsorship (stock car team) and gave me his extra cylinder. I call him when it's empty.
Actually brendon,
Dry rot has nothing to do with the inside of the tire.
The term 'Dry Rot' refers to the visible cracking of the carcass caused by exposure to sunlight and ozone.
In fact, a vehicle stored indoors anywhere near an electric motor (compressor, air exchanger, etc.) will display severe 'Dry Rot' often within one year, caused by the ozone throw off that comes from running electric motors.
Like I said earlier, Nitrogen in racing applications (your slicks) is common and a good plan to avoid unwanted pressure increase with heat.
Regarding your street tires, the pressure rise that occurs as the tire warms is necessary for long tire life and controlled carcass temperature.

BTW. The tire companies LOVE the fact many use nitrogen.
It is very beneficial in reducing tire life due to increased wear LOL.

Good Morning All,
Rob
 

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Maybe dry-rot is a bad choice of terms for what can happen inside the tire but
"dry-rot" on rubber is a function of oxidation and/OR exposure to UV and not just limited to the outside of a tire, so less O2 and other "stuff" inside the tire will minimize any issues occurring internally. Compressed air is just that - compressed atmosphere which still contains the ozones and other pollutants that will casue decay of the rubber.

As for the nitrogen I run in my winter tires, I "over-inflate" with the nitrogen to compensate for the lack of thermal expansion when it heats up - just set it and forget it. I go about 5psig over the recommended cold tire pressure, as this is what I find the nominal pressure rise to be in normal driving for me with regular air inside. My tires end up being at the correct operating pressure regardless of internal temp or atmospheric temp.

The winter tires I chose (and also became a hobby dealer for because I like them so much...) are normally "3-season tires", according to my distributor. Well, I just removed them last week after their fourth winter season and there is plenty of tread left and the rubber is still soft enough for at least another season.

Just pointing out there are benefits to using N in even street tires if done properly, it's not just a marketing scheme; but NOBODY should pay $50 or whatever it is to do it!!
 
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