Good Sam Club Open Roads Forum: Fifth-Wheels: Weight of air vs. Nitrogen


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Campinfan

Washtenaw County, Michigan

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Posted: 08/28/20 11:06am

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So I made an amazing discovery today. I got my new Sailuns partially installed today (so far). When I took the old tires and rims to Discount Tire, they were easy to lift and move into my truck. When I picked up the new Sailuns they were really heavy. Same rims. The old had nitrogen and the new has plain old air. So it must be the air.

Sure it has nothing to do with going from an F rated tire to a G rated. [emoticon]

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12th Man Fan

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Posted: 08/28/20 11:17am

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Be sure to check the pressure in the new tires. When I had DT mount my new tires they said they could only put 80psi in the tires because of their euip.

Good thing I asked.

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Old-Biscuit

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Posted: 08/28/20 11:22am

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Atom for Atom, Nitrogen is Lighter than Air
Nitrogen has an Atomic Weight just over 14 & Oxygen has an Atomic Weight of almost 16

Air,,,,mixture of Oxygen & Nitrogen will be 'heavier' then Nitrogen
Air,,,,78%-Nitrogen, 21%-Oxygen, 1%-Argon, water vapor/trace elements

So your hypothesis is correct......air filled tires are heavier then nitrogen fill ones

Course size/heft of an 'F' rated tire VS size/heft of a 'G' rated tire throws a monkey wrench in the whole concept

LOL......

Is it time for your medication or mine?

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Lynnmor

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Posted: 08/28/20 12:21pm

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Here is one example of the massive loss of weight:

The weight difference between oxygen and nitrogen is less than 3%, but let’s take the full 3%.

One 255/40/17 summer tire holds approximately 13.88 liters (0.5 cu.ft.) of air at 2 bar (29.4 psi).

One liter of air is roughly equal to 1 gram so there are roughly 13.88 grams of air per tire, 55.52 grams in all 4 tires. Nitrogen is 3% lighter than oxygen, but there’s only 22% oxygen in air, so the difference in weight from all 4 tires is 0.3664 grams, that’s a whopping one third of a gram!

Here’s the math: 55.52 gr x 0.03 x 0.22 = 0.3664 gr

To put it in perspective, one official ping pong ball weighs 2.7 grams.

Hammerboy

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Posted: 08/28/20 12:29pm

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Reminds me of a funny story I heard once from a factory maintenance foreman I knew. He told a young apprentice once to get dolly because they needed to bring a small portable air tank to a location and the tank had 150 pounds of air inside. Apprentice fell for it and got the dolly. [emoticon]

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jdc1

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Posted: 08/28/20 12:41pm

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Hammerboy wrote:

Dan

Wonder what the kid would have done if it was a scuba tank with 2,500 psi?

delwhjr

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Posted: 08/28/20 01:22pm

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He would have brought the forklift, of course!! [emoticon]

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Martyn

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Posted: 08/28/20 03:09pm

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It could also be because there is more tread on the new ones! [emoticon]

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agesilaus

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Posted: 08/28/20 03:18pm

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Old-Biscuit wrote:

Atom for Atom, Nitrogen is Lighter than Air
Nitrogen has an Atomic Weight just over 14 & Oxygen has an Atomic Weight of almost 16
LOL......

OK some real numbers the molecular weight of air is about 29 g/mole, the weight of nitrogen gas (remember is is N2 and O2 not N and O) is 28 g/mole. 28/29 is about .965 some you save a whopping 4.5% of the weight of the gas. My educated guess is that there is only 3 or 4 moles of gas in a tire, probably less. And so you save 4 grams of weight and it takes about 30 grams to make one ounce.

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