Airplane tires, If ya got'em, Run'em

[NJT 5573]

Aircraft recaps would be ok on my coach.  (1) Airplane tires are rotational(one direction, birth to death. (2)  FAA requires nitrogen only. No moisture to migrate to cords and present rust problems. (3)  Sprial wrap, seperate textile cords are layered within the replacement tread rubber as it's applied to the tire casing. (4) Time release sidewall antioxidant to prevent cracking. (5) Heres the big one, Tires that have a puncture that has penetrated the innerliner are not repairable..........Thats a flat tire to us........ Guess if I was going to buy some recaps, I'd look inside the tire and see just what I'm getting. Think the last airplane tire I owned was 28 ply.

[Dreamscape]

Nitrogen, that is very interesting. We use that on our hydraulic system accumulators. I would be interested to know the reasoning, is it just for reducing the moisture?
My Father-In-Law used propane to inflate a trailer tire the other day, I had not heard of doing that. He is a Rancher here in Texas, I thought of all kinds of reasons NOT TO. Maybe I am wrong.
Interesting thread NJT5573.

Happy Trails,

Paul

Dreamscape

[Happycampersrus]

Check out this info.


http://www.nitrogendirect.com/N2Info.htm

[tekebird]

1. nitrogen molecules are larger...thus it doesn't seep through the rubber

2. Nitrogen does not expand as much in volume when heated compaired to air

3. Tires run cooler

[kyle4501]

Eliminating oxygen from inside the tire reduces tire aging too.

A flat on a plane is a very different issue than on a bus. Neither is good, & I agree that treating our bus tires better is a good idea. My issue with recaps is the unknown history of the casing.

[Tony LEE]

"1. nitrogen molecules are larger...thus it doesn't seep through the rubber

2. Nitrogen does not expand as much in volume when heated compaired to air

3. Tires run cooler"

A rigorous scientific explanation to back these up (in a practical situation) would add some interest to the thread.

Tony

[DrivingMissLazy]

I  know of some antique car collectors who maintain a nitrogen tank to keep their tires inflated. It is relatively inexpensive to buy a bottle and a regulator.
Richard

[Kristinsgrandpa]

I've seen nitrogen generators advertised,  expressly to inflate automotive (and truck) tires to the tune of over $1400.

I think I'll skip it.

ED

[bobofthenorth]

78% of the air we breath every day is nitrogen.  This sounds like a scam to me.

[gus]

NJT,

You must have had a heck of a big airplane to have 28 ply tires. My airplane has 4 ply and came originally with 2 ply!

Nitrogen may be required in transport class aicraft but not in light aircraft. 99% of lightplanes use just plain ole local air.

High flying airplanes use nitrogen so the tire won't expand so much at very high altitudes.

Also in light aircraft there is no requirement to replace a punctured tire, repair is up to the A&P doing the work. The only no-no I know of is tread worn down to cord, cuts to cord or deep cracks.

Lightplane tubes used to be made of natural rubber and so would lose air through the tube over time. Don't know if they still are but mine leak down so I guess they are.

teke,

1. Don't buy this one, air is mostly nitrogen anyway.
2. Agree with this one
3. They don't run any cooler they just don't expand as much.

Nitrogen is the latest scam, another way of milking vehicle owners of their dollars. It is obviously better than air but not necessary for normal use.

The biggest problem with nitrogen is that it comes in very high pressure cylinders. Those things can blow a tire to shreds and you too.

[HighTechRedneck]

Indeed, 78% of regular air is Nitrogen, but it is the water vapor and that pesky little 21% Oxygen that make air less stable.   As for how much real benefit there is in using Nitrogen for standard vehicle usage, I am doubtful.  I've seen a lot of claims but I feel like it is just a vanity trend.

As I understand it, the reason commercial airlines, military aircraft and the space shuttle use Nitrogen in their tires is for the temperature stability and dryness. The tires can get extremely cold at high altitudes and then heat very rapidly on touchdown.  Race cars also use it for temperature stability since their tires get extremely hot.  In collectors cars I can imagine the anti-rust and antioxident qualities of Nitrogen (it is a primarily inert element) being mildly beneficial but still more vanity than functional.

[Tony LEE]

I always thought that water vapour and all of the major constituents of air act essentially as ideal gases whose behavior as temperature changes all follow the Gas Law. This means that at practical temperatures found in tyres, the increase in pressure for a given increase in temperature will be the same for normal air as for say, nitrogen.
The only time this will vary a little - and will mean the air mixture giving a lower pressure than nitrogen - will be if the temperature inside the tyre falls below the dew-point causing some of the water vapour to condense out. This effect is small and would need some accurate instrumentation to pick it up.

The amount of water the air in a tyre holds is quite small -- a maximum of about 5 grams. Commercial aircraft fly at high altitudes where the temperature is way below zero and so the effects of ice causing out of balance during the great acceleration as they contact the ground could be significant

As for the oxygen inside the tyre. This is the same as the oxygen on the outside of the tyre and since the UV light and road contaminants are also on the outside of the tyre, it is not surprising that the outside of the tyre is the side to show aging well before the inside.

Tyres running cooler?  Maybe the thermal conductivity of nitrogen is different to that of air, but it is hard to see how that would have any significant effect on the tyre temperature. It could be argued that if nitrogen was a better conductor then it would conduct more heat from brake drums and make the tyres hotter.  Anyway, it would have to be a second or third-order effect and be far less significant than the much higher temperatures of those tyres on the sunny side of the vehicle.

As for using them on road vehicles -- aren't they all very rounded compared to road tyres, and designed to operate at significantly higher pressures in completely different operating conditions?

As for size of molecules -- oxygen atoms are heavier and so presumably bigger than nitrogen atoms so I guess the molecules might be bigger too -- and anyway, I doubt whether relative permeability of half an inch of tyre rubber would be of any significance at all compared to other types of leakage paths.

[TomC]

The last time I had my tires rotated at Costco, the tire stems had green plastic caps on them, which sort of pissed me off since I had chrome metal ones with O rings (I didn't notice till a few days later).  The green caps means the tire has been filled with nitrogen.  Costco does that for free, as a matter of policy (at least at the Costco I go to).  Good Luck, TomC

[HighTechRedneck]

Here is the story behind Costco's use of Nitrogen. (article on right side of page)

http://www.costcoconnection.com/connection/200410/?pg=17

I think the benefits they cite are based on careless, or automotively clueless, drivers that don't monitor their tire pressure.  A low tire will waste fuel and run hotter.  But I don't see any way that a Nitrogen inflated tire will outperform a properly maintained tire inflated with standard air in standard road usage.

If the claim about seepage resistance "holds air" (pardon the pun) then I could see it as a fuel saving measure for drivers who don't routinely check their tires.  Perhaps it would be a convenience for those of us who do monitor our tire pressure, fine if it is free but not worth added expense.

[Stan]

On the question of oxygen leaking through the rubber faster than nitrogen, then I agree with Hightechredneck. If you initially fill the tire with 78% nitrogen (ordinary air) and assume that you let all the oxygen escape before topping it up then the tire will be 96% nitrogen (20% of the 20% lost). Do that a second time and the tire will be over 99% nitrogen (the same as the expensive nitrogen generators produce).

Obviously, you don't wait for a 20% loss before you top up, but this just shows how quickly you can change the percentage of nitrogen in the tire by replacing the lost oxygen with ordinary air.

On the topic of leaking: Last summer I donated an old vehicle to a museum. It had new tires and tubes installed in 1964 and sat around outside until 1985 when I moved. I trailered it to my new place and parked it in the back of the shop. When I took it out last year, one tire was flat. The other three looked OK and I didn't have to add any air before loading it.