weathershak
Delaware
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Joined: 12/11/2006
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I am sticking with human produced Methane. Most of the time it is fun to produce, and if you get a leak, it will smell like S...., well, you know.
Don't like the view?? Then change it and Go Camping    Our pics
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patinlouisiana
Baton Rouge, La
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johnrbd wrote:Wonder if anyone has tried helium in their tires. Is it doable and economically feasible? If it was, mpg could be improved.
Not a good idea!
We use helium for leak testing as it will leak out of small cracks that air will not. It is much less dense that air.
Think about kid's baloons.
The one you blow up stays inflated for weeks. the one filled with helium stays inflated for just a few days.
I never get lost! Someone always tells me where to go!
2012 Prime time Tracer 230FBS Touring Edition
2010 Toyota Sequoia Limited 4X2
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rehoppe
Denver
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Joined: 01/30/2009
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One good thing about nitrogen is that it's DRY. Contains little if any moisture. So less to rot the tires?
Hoppe
2011 Dodge 1500 C'boy Caddy
2000 Jayco C 28' Ford chassis w V-10
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Coach-man
Florida
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rehoppe wrote:One good thing about nitrogen is that it's DRY. Contains little if any moisture. So less to rot the tires?
X2, I was a big "NON BELIEVER" until I was talked into "trying it out in my Jeep. It does help, it won't allow moisture to "dry Rot" the tires and it improves millage, although very little. I won't run out and replace my air with nitrogen, but when I need to replace my tires I will have them filled with nitrogen!
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skimask
ND
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Jagtech wrote:Just curious... what pressure increase is seen in an aircraft tire at say, 35,000 ft? Can you estimate the tire pressure at that alt? What keeps the tire from bursting at high altitudes? Does nitrogen help vs just air in this case?
Absolute pressure doesn't change...except for the temperature drop, which would cause the absolute pressure inside the tire to drop a bit.
However, differential pressure between the inside of the tire and the ambient air will increase.
Think of it this way...
There's about 14.69 psi at sea level...
There's practically zero psi in outer space.
So, that tire you aired up to 100psi at sea level, will have about 114.69 psi in outer space...assuming "temperature" (which doesn't/can't really exist in outer space in the first place) stays the same.
At the same time, at 35,000ft, the outside pressure is about 3.5 psi.
So, you'd gain about 11.2 psi of DIFFERENTIAL pressure inside the tire...again, neglecting the effects of temperature. Factor in the colder air at altitude, and it offsets that pressure increase a fair amount.
Very roughly, temp loses about 2.5 degrees per 1,000 ft, up to the tropopause (which varies in height), but assuming it's above 35,000ft, the temp at 35,000ft would be roughly -30F if the sea level temp was about 60F.
So, if you've got an aircraft tire pressurized to 100 psi at sea level at 60F, at 35,000ft it would read about 115psi.
Factor in the temperature change (-2% for each 10F drop, give or take), and you get roughly 96psi.
Again, VERY VERY rough figures, but the idea still stands.
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patinlouisiana
Baton Rouge, La
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Let me see if I have this straight in my head?
Atmospheric pressure at sea level is about 14.7 psi
Atmospheric pressure at 10,000 feet is about 10.1 psi
The difference is 4.6 psi.
If I have 40 psi in my tires at the beach the go up in the mountains to 10,000 feet my tire ppressure would increase to 44.6.
Correct or not?
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PhilR.
Central Texas
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I only run an ~80% Nitrogen mixture in my tires, and I've not ever in all my years have I had a problem with dry rot. All of my tires needed replacing because of wear (or "useage").
I guess that if I had tires that are hardly ever used and I liked them an unusual amount, that I might be talked into using nitrogen. However, I am just going to stick with my usual mixture, as it has worked just fine.....
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patinlouisiana
Baton Rouge, La
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You know what would be "cool"?
Liquid Nitrogen!
Actually I think it would be quite cold ;-)
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skimask
ND
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patinlouisiana wrote:Let me see if I have this straight in my head?
Atmospheric pressure at sea level is about 14.7 psi
Atmospheric pressure at 10,000 feet is about 10.1 psi
The difference is 4.6 psi.
If I have 40 psi in my tires at the beach the go up in the mountains to 10,000 feet my tire ppressure would increase to 44.6.
Correct or not?
Give or take a bit, yes. The tire pressure INSIDE the tire, the ABSOLUTE pressure hasn't changed, but the DIFFERENTIAL pressure between the inside and outside of the tire has increased.
That also assumes exactly the same temp at 10,000ft as sea level.
Taking the "standard" temp lapse rate into account, if you aired up at sea level at 60F, 10,000ft would be about 40F, pressure drop from temp alone would be about 4% of the total, dropping it to about 38.5. Add the 4.6 psi back in for the altitude change, and you have about 43.1psi.
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skimask
ND
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patinlouisiana wrote:You know what would be "cool"?
Liquid Nitrogen!
Actually I think it would be quite cold ;-)
And a hard ride...for awhile anyway.
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