Nitrogen for tires?
#1
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Nitrogen for tires?
Has anyone tried replacing the air in their tires with Nitrogen. I heard it improves handling, gas mileage and tire life.
#3
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Re: Nitrogen for tires?
Following quotes from an Engineering Forum:
Handling? NO.
Gas Mileage? NO.
Tire Life? NO.
Originally Posted by speedexracer
Has anyone tried replacing the air in their tires with Nitrogen. I heard it improves handling, gas mileage and tire life.
Gas Mileage? NO.
Tire Life? NO.
Dry air or dry nitrogen will follow the combined gas laws more accurately than air containing moisture, but the difference really is academic.
Oxidation of the rubber inside a tyre has never been of concern to me, nor anyone else I know. I have only ever seen tyres fail from normal wear, cuts from impact or sharp objects or by oxidation or ozone attack of the outer carcase. The cracks in the sidewall, always start outside, never on the inside.
Snake oil for sure.
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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
Oxidation of the rubber inside a tyre has never been of concern to me, nor anyone else I know. I have only ever seen tyres fail from normal wear, cuts from impact or sharp objects or by oxidation or ozone attack of the outer carcase. The cracks in the sidewall, always start outside, never on the inside.
Snake oil for sure.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
Race teams will often use nitrogen to fill tires, but largely out of conveience rather than due to any performance benefit. No ancilliary equipment needed to fill a tire if you have a bottle of nitrogen. If you use a compressor you either need a generator or need to find a place to plug in, or need a gas powered compressor.
There is absolutely no harm in using nitrogen to fill tires, so as long as the shop didn't hit you up with any extra charges just shrug it off.
There is absolutely no harm in using nitrogen to fill tires, so as long as the shop didn't hit you up with any extra charges just shrug it off.
The question about nitrogen in tires has come up in other lists on the web as well. Let me clarrify a few points.
1. Air is 78% nitrogen, N2, and 21% oxygen, O2. So even if you put air in the tire, it'* already 78% nitrogen. Many of the so called nitrogen generators don't produce much more than 90% nitrogen.
2. At relatively low pressures (ie tire pressures) N2, O2 and water vapor will all behave as ideal gases, and follow PV=nRT. Pressure will increase or decrease to the same extent as the temperature increases or decreases regardless of which gas is in the tire. (Even at 300 psi, which is about 20 atm, there is little deviation from ideality.) Therefore the comments about N2 not changing in pressure as the temperature changes are without merit.
3. The rate of effusion (or diffusion) of a gas through a porous membrane depends on the molar mass and to some degree on the molecular diameter. N2 and O2 are almost the same size and N2 is lighter than O2 (28 g/mol vs 32 g/mol) so if either gas were to effuse out of the tire, nitrogen would do it more quickly. Luckily, tires are designed not to be porous membranes.
4. N2 and O2 both have essentially the same specific heat capacity, about 1.0 J/gK, and thermal conductivity, about 0.00026 W/cmK. Water vapor has a specific heat capacity of about 2 J/gK. But remember, water vapor will constitute less than 1% of the air in the tire. So the idea that N2 has different heat handling properties is also without merit.
5. The ozone, O3, in the atmosphere, which is a ground level pollutant, will do a great deal more damage to your tires than the O2 inside the tire. For instance, don't leave a condom out in the air in Los Angeles for a few days. It will develop lots of tiny holes and weaken.
spdracer22 says that dry air is preferably to air with a lot of water vapor. As a tire heats up, the very small amount of H2O present will be in the vapor state which may contribute to the overall pressure very slightly.
Several have suggested that N2 in a high pressure tank is more portable and requires no electricity. That would make sense, particularly for aircraft tires.
I find no reason to believe that N2 is going to produce a "better ride" or "better handling".
The bottom line is that for general passenger car tires or truck tires there is nothing to be gained (other than portability) by using nitrogen rather than air. The biggest gain will be $$$ by the companies that sell nitrogen handling equipment and the tire merchants that appeal to ignorant customers. And who is the biggest loser? Yep, the consumer.
1. Air is 78% nitrogen, N2, and 21% oxygen, O2. So even if you put air in the tire, it'* already 78% nitrogen. Many of the so called nitrogen generators don't produce much more than 90% nitrogen.
2. At relatively low pressures (ie tire pressures) N2, O2 and water vapor will all behave as ideal gases, and follow PV=nRT. Pressure will increase or decrease to the same extent as the temperature increases or decreases regardless of which gas is in the tire. (Even at 300 psi, which is about 20 atm, there is little deviation from ideality.) Therefore the comments about N2 not changing in pressure as the temperature changes are without merit.
3. The rate of effusion (or diffusion) of a gas through a porous membrane depends on the molar mass and to some degree on the molecular diameter. N2 and O2 are almost the same size and N2 is lighter than O2 (28 g/mol vs 32 g/mol) so if either gas were to effuse out of the tire, nitrogen would do it more quickly. Luckily, tires are designed not to be porous membranes.
4. N2 and O2 both have essentially the same specific heat capacity, about 1.0 J/gK, and thermal conductivity, about 0.00026 W/cmK. Water vapor has a specific heat capacity of about 2 J/gK. But remember, water vapor will constitute less than 1% of the air in the tire. So the idea that N2 has different heat handling properties is also without merit.
5. The ozone, O3, in the atmosphere, which is a ground level pollutant, will do a great deal more damage to your tires than the O2 inside the tire. For instance, don't leave a condom out in the air in Los Angeles for a few days. It will develop lots of tiny holes and weaken.
spdracer22 says that dry air is preferably to air with a lot of water vapor. As a tire heats up, the very small amount of H2O present will be in the vapor state which may contribute to the overall pressure very slightly.
Several have suggested that N2 in a high pressure tank is more portable and requires no electricity. That would make sense, particularly for aircraft tires.
I find no reason to believe that N2 is going to produce a "better ride" or "better handling".
The bottom line is that for general passenger car tires or truck tires there is nothing to be gained (other than portability) by using nitrogen rather than air. The biggest gain will be $$$ by the companies that sell nitrogen handling equipment and the tire merchants that appeal to ignorant customers. And who is the biggest loser? Yep, the consumer.
#4
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In simpler terms (my voice here):
Handling: Sidewall and tread face flex and the resistance to that flex is determined by the pressure inside the tire. Absolute pressure, regardless of the type of gas used.
Tread wear: Absolutely unaffected by what is inside your tires. Your tread could care less if the inside of the tire has 35psi or helium, N2, or pure oxygen.
Tire life: You will wear out your tread from friction on the road surface long before any contaminants inside your tire could do any damage.
Aircraft use N2 in tires for totally different reasons.
Handling: Sidewall and tread face flex and the resistance to that flex is determined by the pressure inside the tire. Absolute pressure, regardless of the type of gas used.
Tread wear: Absolutely unaffected by what is inside your tires. Your tread could care less if the inside of the tire has 35psi or helium, N2, or pure oxygen.
Tire life: You will wear out your tread from friction on the road surface long before any contaminants inside your tire could do any damage.
Aircraft use N2 in tires for totally different reasons.
#7
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Actualy if you think about it, if your tires have a lower density gas(im pretty sure the nitrogen is lesser in density) than the gas outside, then it would effect roll. But in this case, it will have noticable effects because the change is not drastic enough.
#9
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NASCAR uses it primarily because they have to make last-minute tire pressure changes 2 laps befor a pitstop. They can't have a compressor in every pit stall, so they have 3000psi bottles of N2 there.
#10
Retired
Just spent 8 years in Army Aviation, and I noticed that they fill the helicopter tires with Nitrogen. I asked why, and they said that Nitrogen does not expand and contract like oxygen does. Or the equivelant of finding soft tires during the winter time, or over inflated in the summer time.
Ever have someone tell you to change the air in your tires every summer and winter??
Ever have someone tell you to change the air in your tires every summer and winter??
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