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How many gallons of air does a tire hold?

You need at least ten ice cream pails full. Pour carefully. :haha::haha:

Depends on pressure if you want to measure volume, but why do you ask?
 
4X4HIGH said:
Since when is air measured in gallons. :haha:
Click to expand...

Well, we know that a gallon of water weights about 7 Lbs, and a gallon of gasoline weighs about 6 Lbs.

What you need to do is weigh the tire BEFORE you put any air in it, then fill it up to whatever pressure you want. Then weigh it again. The difference in weight will be the amount of POUNDS of air.

Divide that number by the number of pounds per gallon for air, and you'll have your answer! :saweet:



Holy cow! This "staying at a Holiday Inn" thing really works!....





:usaflag:
 
4X4HIGH said:
Since when is air measured in gallons. :haha:
Click to expand...

Tanks are measured in gallons. Now the question is how do they determine the gallon capacity for the tank? Is it at max rated PSI, or is it a standard PSI for all tanks (like 40 PSI)?:confused:
 
Interesting question...but lets put that engineering degree to use and work through it....realize that air compresses. So if you are asking the volume of the tire that is something different...

Lets find the area inside that tire:

I am assuming we'll subtract 1" from each side for the rubber material so we have a inner diameter of 31" and a width of 10.5". Area of a circle is pi x radius squared so

15.50^2 x 3.14 = 725.47 - > Volume of a cylinder = area of the circle x length so -> 725.47 x 10.5 = 7617.39

Now lets subtract the volume of the rim. Hard to get it exact so lets assume a diameter of 14" because it does not fill the 15". Using same formulas ->

Area = 7^2 x3.14 = 153.86 Volume -> 153.86 x 10.5 = 1615.53

Okay now we want volume of tire - volume of rim =-> 7617.39 - 1615.53 = 6001.86ci lets call it 6000ci

Now, gallons of air depends on pressure but lets go with somewhat standar -> 35psi.

The formula for the volume of a compressed gas is
pa Va = pc Vc (1)
where
pa = atmospheric pressure (14.7 psi, 101.325 kPa)
Va = volume of the gas at atmospheric pressure (cubic feet, cubic meter)
pc = compressed pressure (psi, kPa)
Vc = volume of the gas at compressed pressure (cubic feet, cubic meter)


Cubic inches to cubic feet = 1ci = 0.0005787cf

Cubic feet to gallons = 1cf = 7.48gal


Now 6000ci = 3.47cf


so formula above using 35psi


Va = pc Vc / pa


Va = 35 x 3.47 / 14.7 = 8.26cf


Converting to gallons 8.26 x 7.48 = 61.8gallons of air.


SO 61.8gal of compressed air.


Now, if you are asking because you want an air tank for desert side inflation or something, you tires hold roughly the size of your tire at same PSI so something like 3.47cf x 7.48gal/cf = 25.955 = 26gal


So air tank ar 35psi must be 26gal to fill the tire to 35psi. Air tank at say 175psi will be much smaller. I think you could just factor it down 35/175 x 26 = 5.2gal but I haven't worked through it yet. To fill 4 tire would require like a 20 gallon tank. Much easier to bring a small CO2 cylinder along that hod 2800psi because it will fill all your tires no problem.


Mike












​
 
And there's your answer.






























Holy schnikey!:eek1: I can almost remember a time when I knew math that well. My job doesnt really require anything more than simple arithmatic, so I've gotten rusty on anything more advanced than 2+2=4.
 
Too many variables.

1) Pressure (altitude)

2) Humidity (water in the air)

3) Pollutants (Air would be heavier in NY City than it would be in BFE im guessing)

So there you have it, my cop out answers.
:D
 
pseudomike said:
Interesting question...but lets put that engineering degree to use and work through it....realize that air compresses. So if you are asking the volume of the tire that is something different...

Lets find the area inside that tire:

I am assuming we'll subtract 1" from each side for the rubber material so we have a inner diameter of 31" and a width of 10.5". Area of a circle is pi x radius squared so

15.50^2 x 3.14 = 725.47 - > Volume of a cylinder = area of the circle x length so -> 725.47 x 10.5 = 7617.39

Now lets subtract the volume of the rim. Hard to get it exact so lets assume a diameter of 14" because it does not fill the 15". Using same formulas ->

Area = 7^2 x3.14 = 153.86 Volume -> 153.86 x 10.5 = 1615.53

Okay now we want volume of tire - volume of rim =-> 7617.39 - 1615.53 = 6001.86ci lets call it 6000ci

Now, gallons of air depends on pressure but lets go with somewhat standar -> 35psi.

The formula for the volume of a compressed gas is
pa Va = pc Vc (1)
where
pa = atmospheric pressure (14.7 psi, 101.325 kPa)
Va = volume of the gas at atmospheric pressure (cubic feet, cubic meter)
pc = compressed pressure (psi, kPa)
Vc = volume of the gas at compressed pressure (cubic feet, cubic meter)


Cubic inches to cubic feet = 1ci = 0.0005787cf

Cubic feet to gallons = 1cf = 7.48gal


Now 6000ci = 3.47cf


so formula above using 35psi


Va = pc Vc / pa


Va = 35 x 3.47 / 14.7 = 8.26cf


Converting to gallons 8.26 x 7.48 = 61.8gallons of air.


SO 61.8gal of compressed air.


Now, if you are asking because you want an air tank for desert side inflation or something, you tires hold roughly the size of your tire at same PSI so something like 3.47cf x 7.48gal/cf = 25.955 = 26gal


So air tank ar 35psi must be 26gal to fill the tire to 35psi. Air tank at say 175psi will be much smaller. I think you could just factor it down 35/175 x 26 = 5.2gal but I haven't worked through it yet. To fill 4 tire would require like a 20 gallon tank. Much easier to bring a small CO2 cylinder along that hod 2800psi because it will fill all your tires no problem.


Mike












​
Click to expand...

Mike, can I call you when my five year old has questions about math?
 
pseudomike said:
Interesting question...but lets put that engineering degree to use and work through it....realize that air compresses. So if you are asking the volume of the tire that is something different...

Lets find the area inside that tire:

I am assuming we'll subtract 1" from each side for the rubber material so we have a inner diameter of 31" and a width of 10.5". Area of a circle is pi x radius squared so

15.50^2 x 3.14 = 725.47 - > Volume of a cylinder = area of the circle x length so -> 725.47 x 10.5 = 7617.39

Now lets subtract the volume of the rim. Hard to get it exact so lets assume a diameter of 14" because it does not fill the 15". Using same formulas ->

Area = 7^2 x3.14 = 153.86 Volume -> 153.86 x 10.5 = 1615.53

Okay now we want volume of tire - volume of rim =-> 7617.39 - 1615.53 = 6001.86ci lets call it 6000ci

Now, gallons of air depends on pressure but lets go with somewhat standar -> 35psi.

The formula for the volume of a compressed gas is
pa Va = pc Vc (1)
where
pa = atmospheric pressure (14.7 psi, 101.325 kPa)
Va = volume of the gas at atmospheric pressure (cubic feet, cubic meter)
pc = compressed pressure (psi, kPa)
Vc = volume of the gas at compressed pressure (cubic feet, cubic meter)


Cubic inches to cubic feet = 1ci = 0.0005787cf

Cubic feet to gallons = 1cf = 7.48gal


Now 6000ci = 3.47cf


so formula above using 35psi


Va = pc Vc / pa


Va = 35 x 3.47 / 14.7 = 8.26cf


Converting to gallons 8.26 x 7.48 = 61.8gallons of air.


SO 61.8gal of compressed air.


Now, if you are asking because you want an air tank for desert side inflation or something, you tires hold roughly the size of your tire at same PSI so something like 3.47cf x 7.48gal/cf = 25.955 = 26gal


So air tank ar 35psi must be 26gal to fill the tire to 35psi. Air tank at say 175psi will be much smaller. I think you could just factor it down 35/175 x 26 = 5.2gal but I haven't worked through it yet. To fill 4 tire would require like a 20 gallon tank. Much easier to bring a small CO2 cylinder along that hod 2800psi because it will fill all your tires no problem.


Mike












​
Click to expand...

= buy a CO2 tank

Good for you man on going through all the proper steps :waytogo:
 
Definitely an approximate answer. For air tank sizing it is however a direct relationship as the variables are equal for both the tire and tank.

I'd be happy to help your 5 yr old. I actually teach a few math classes at the local Community college from time to time. I guess I'm one of those weirdos that actually likes math :).
 
What is heavier... a pound of air or a pound of feathers... :haha:

Seriously though, a gallon is a gallon... no matter what pressure the internal material is experiencing.

Maybe the relevant question is something like "How big of an air tank... and at what pressure do I need to refill my X size tires Y times?"

Mike's math was headed in that direction... I can dig it!

Answer as already stated - get CO2 tank. Compressed air doesn't expand anywhere near as much as equivalent volume/pressure of CO2 due to the phase change CO2 undergoes...

or on board air is VERY nice!
 
Math and science are your friend. :deal: :waytogo:

Now can you use the Ideal Gas Law to tell me how many bushels of electrons I need to power my radio? :D
 
BGKYK5 said:
Math and science are your friend. :deal: :waytogo:

Now can you use the Ideal Gas Law to tell me how many bushels of electrons I need to power my radio? :D
Click to expand...


That is an easy one...none providing you use a crystal radio. Of course you'll probably want to amplify the sound....which you could do via modulation with gas pressure differentials.
 
blazerbones said:
No ideal gas law needed... electrons have no volume... so you can never get a bushel of them.

:haha::haha::haha:
Click to expand...

But electrons have mass (9.10938188 × 10^-31 kilograms or 1/1836 that of a proton), so you could actually calculate the electron mass it would take to fill the tire:wink1:
 
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