Nitrogen...

[Michael W.]

Re: Nitrogen...

Paul, There are some pit falls to Automotive tires and there pressures, and loss of pressure due to small leaks over time has never changed, I think that corvettes really don't benefit all that much from nitrogen unless its a daily driver. The other side of the coin is as I say is its made for those people who drive there cars for a long period of time before there next service, as there just are not many people that check there pressure on a regular basis.

Edward-

What you say is true except that nitrogen makes no difference- it leaks out at exactly the same rate as air in any given tire. The TPM systems that are very common on today's cars don't indicate a problem with air leakage, they demonstrate how often we have historically forgotten to check pressures. It's simply highlighting an underlying problem.

[Craig J.]

Re: Nitrogen...

If folks feel better with Nitrogen fills, great! Regular air works fine for me...but I check pressure every couple weeks or so on the daily drivers, and I check pressure every time I take out the fun cars.

Those TPMS sensors seem to be marginally useful...my wife's Subaru has them, and unless the pressure drops below 26 PSI, they won't signal low pressure. Factory recommends 33 psi front, 32 rear, so 26 is way too low IMHO.

Maybe these sensors are bad? I'd think that a warning at a 10% pressure variance would be better than 20%.

[Duke W.]

Re: Nitrogen...

The most important issue is to have a DRY supply of gas, whether air or commercial nitrogen. Commerical nitrogen is dried and has very low moisture content. Humid air can lead to condensation when the temperature drops and this will reduce tire pressure and possibly cause a warning on vehicles with TP sensors.

My home compressor has a water trap and desiccant. I also try to pick low humidity days to turn it on and check tires.

On average a good tire that is well sealed to the wheel should lose no more than one psi per month.

Also keep in mind that measured tire pressure will increase/decrease about one psi with every 10 degree F increase/decrease in tire temperature.

Duke

[Leif A.]

Re: Nitrogen...

Leif------


Keep in mind that just because others, including myself, have contradictory opinions on nitrogen inflation for tires, that does not mean that you should not have submitted your original post. You were simply reporting relative to your experience and business practices. That's a fine and appropriate thing to do and it stimulated further discussion and information. Contradictory opinions or information should never discourage folks from posting.

I agree, Joe. "I may not always agree with what you say but I will defend to the death your right to say so."

[Michael W.]

Re: Nitrogen...

Also keep in mind that measured tire pressure will increase/decrease about one psi with every 10 degree F increase/decrease in tire temperature.

Duke

This is key in my area (Ontario Canada) where summer temps can approach 100 degrees F and winter time dip to 30 below. That's a 13 psi variation which will set off any TPM warning system.

[John M.]

Re: Nitrogen...

I think we should all read again what GM, a company with a lot of bright automotive engineers, has stated so diplomatically, fuggedaboudit.

[Joe L.]

Re: Nitrogen...

All------


Some time ago I was at my local America's Tire store purchasing a set of tires. There was a person standing next to me at the counter purchasing a set from another counter man. The person asked if he could pay extra and have his tires filled with nitrogen. The counter man told him that America's Tire did not supply nitrogen filled tires because they did not believe it provided any significant benefit. I've always felt pretty good about America's Tire but I felt even better after hearing that

I suppose it's possible that they've changed their policy by now but, if so, I expect it was influenced by "popular demand" from guys like the one that was standing next to me.

[Domenic T.]

Re: Nitrogen...

I didn't have time to read all but nitrogen HAS to be put in ALL large aircraft because it holds the presure at all altitudes and temps. We are talking 10 miles high and a temp change of + 50c to - 70c. If air would be used the tires would blow up in the wheel wells.
Nitrogen is a manufactures REQUIREMENT along with a FAA requirement.

DOM

[Duke W.]

Re: Nitrogen...

If air would be used the tires would blow up in the wheel wells.
DOM

Air is no more likely to "blow up" a tire than nitrogen. They both behave like an ideal gas, so both will see similar changes in tire air pressure as ambient temperature and pressure change. Commercial nitrogen is also very dry, so condensation and ice formation in the tire at the very low temperatures in the stratosphere are not issues.

Large, heavy aircraft have tires that are inflated to something on the order of 250 psi, and if such a tire were to explode in the wheel well, a fire is very likely.

Filling the tires with nitrogen nearly eliminates the possibility that a wheel well tire explosion will start a fire, and that's the primary reason why aircraft use commercial dry nitrogen in the tires.

Duke

[Domenic T.]

Re: Nitrogen...

Duke,
Hate to dissagree but there is NO chance of a fire at altitude, a fire NEEDs Oxygen and oxygen is to expanded to burn, there is not enough at altitude. I have captained jets since 1979 and also held a FAA mechanics licence since 1975. Engine fires at altitude do not exsist they are usually a grounded harness or a leak in the hot section of the engine. Engine fires are at low altitudes.
The engine can only stay running (keeping it's fire ) because it compresses the expanded air so it will burn the fuel. That's the same air you breath inside the cabin, compressed air @ about 9.3 PSI. Without compressing the air nothing can catch fire when the outside pressure is that low. Only the pressure vessle (cabin) can burn what is inside it and the tires are not in the pressure vessle.
I have nitrogen in my shop but do not use it in my car tires because I am to lazy to do it. But tires usually say a cold PSI. Aircraft tires will expand with compressed air enough so as to do damage inside the wheel wells. Also the rim temps have lead blow plugs because the brakes on aborted take offs heats the rims hot enough to melt the lead which releases the nitrogen.
So there is no chance of a tire blowing in the wheel well and causing a fire. The air expands so much that the potato chip bags pop and the cabins are usually maintained at 6,500 ft. Imagine air in a tire at 51,000 ft?

DOM

[Joe L.]

Re: Nitrogen...

Duke,
Hate to dissagree but there is NO chance of a fire at altitude, a fire NEEDs Oxygen and oxygen is to expanded to burn, there is not enough at altitude. I have captained jets since 1979 and also held a FAA mechanics licence since 1975. Engine fires at altitude do not exsist they are usually a grounded harness or a leak in the hot section of the engine. Engine fires are at low altitudes.
The engine can only stay running (keeping it's fire ) because it compresses the expanded air so it will burn the fuel. That's the same air you breath inside the cabin, compressed air @ about 9.3 PSI. Without compressing the air nothing can catch fire when the outside pressure is that low. Only the pressure vessle (cabin) can burn what is inside it and the tires are not in the pressure vessle.
I have nitrogen in my shop but do not use it in my car tires because I am to lazy to do it. But tires usually say a cold PSI. Aircraft tires will expand with compressed air enough so as to do damage inside the wheel wells. Also the rim temps have lead blow plugs because the brakes on aborted take offs heats the rims hot enough to melt the lead which releases the nitrogen.
So there is no chance of a tire blowing in the wheel well and causing a fire. The air expands so much that the potato chip bags pop and the cabins are usually maintained at 6,500 ft. Imagine air in a tire at 51,000 ft?

DOM

DOM-----

I believe the use of nitrogen in aircraft tires is primarily to reduce the risk of fire or explosion. A fire or explosion can be propagated by the oxygen content of air. Even at jet cruising altitudes there is oxygen although obviously a lower concentration. If there were not the jet engines would not operate and there would be nothing to compress to support life in the cabin. However, even if the risk of fire at altitude was zero, the oxygen in an air-inflated tire would still present a greater risk of propagating a fire than a nitrogen filled tire. The FAA does not like to take any avoidable risks.

In addition to the above, though, is the fact that commercial aircraft are not always operating at low oxygen concentration altitudes. During those lower altitude periods, including ground operation, the oxygen in an air-filled tire presents a greater risk of propagating or exacerbating a fire. I believe this is why the FAA started requiring the use of nitrogen for most commercial aircraft. I think it's "overkill" but in aviation any risk is minimized.

I do not think the nitrogen inflation requirement exists for the vast majority of general aviation aircraft.

[Michael W.]

Re: Nitrogen...

I wondered when someone would drag out the 'cause they use it in aircraft' argument. As Duke and others have pointed out, the reasons why nitrogen is used have nothing to do with expansion coefficient. Although nitrogen has the side benefit of not supporting combustion, the principal reason (also pointed out above) is the 'dryness' of nitrogen vs. typical compressed air plus the portability of nitrogen bottles.

Aircraft tires are subjected to temps in the -60*F range at altitude for hours on end during cruise. This would give any trapped moisture time to freeze solid into a lump. Upon landing where a tire goes from stopped to the touchdown speed of possibly 200+ mph in a split second, the imbalance would at a minimum shake the aircraft violently if not destroy the tire.

If used my cars in the same manner then nitrogen (or any dry gas) would make sense.

[Domenic T.]

Re: Nitrogen...

Joe,
Yes there is the same oxygen raito at all attudes, BUT again, for the egine to burn fuel it REQUIRES many stages of compressors to squeeze the expanded air small enough to burn, each stage compresses the air more s it go's from one to the next For example your lungs would have to be about 9 cubic feet to get the same amount of air as they do at sea level.
Mike,
I am only stating fact! I only bought aircraft up because it is regulated. You Need to do some reading, I had to to pass my Goverment tests and I refruse to believe what you think you know about something you are not familiar with.


DOM

[Martin M.]

Re: Nitrogen...

In regards to tires losing pressure over time, I wonder how much air is lost every time we check tire pressure.

Just askin'

Marty

[Michael W.]

Re: Nitrogen...

Mike,
I am only stating fact! I only bought aircraft up because it is regulated. You Need to do some reading, I had to to pass my Goverment tests and I refruse to believe what you think you know about something you are not familiar with.


DOM

Dom-

I was in the commercial airline business for 31 years working in the engineering, design and customer support areas of world's largest manufacturer of gas turbine engines. Got to see and learn a few things over the decades.

You may refuse to believe what's being said but it's simple indisputable physics- inside or outside the airline business.