How many gallons of air does a tire hold?

[boggerless]

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!



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

what aboot heat on the tire from driving?will it boil over?can i make spagetti in the water?will it taste funny?i know,lotso n00b questions but i'm hungry.

 

[misterfnygy]

concerning pseudomike's math. You have to account for the air naturally in the tire at 14.7 psi- subtract that from your total to get a little closer.

Just try to get enough 5 gal jugs to hold the air, it would be a bitch to tie down 20 milk jugs...

 

[BGKYK5]

What you should do is fill your tires with 50 PSI or helium to make them lighter.

Or better yet hydrogen, then you could reseat beads with just a match.

 

[wasted wages]

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.

I would have just cut the tire open and had a lot of 1 gallon milk jugs sitting arround, and see how many I could stuff in there...