How many 16 gram CO2 cylinders for a 17" tire?

[M. MacDonald]

Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?

Dealer says a lot, maybe 7-8 cylinders.

Anyone need to use one?

Tia.

Mack

[Ken Abrams]

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.

As usual, the dealer doesn't know jack-shit so he is guessing.........and a
piss poor guess too, I think.
My guess is ONE to get it "limpable" (20-30 lbs) and TWO to get it back up
to 40.............assuming that the original hole is plugged or very tiny.

[IdaSpode]

On Mon, 17 Sep 2007 22:03:49 GMT, "Ken Abrams"

Post by Ken Abrams

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.

As usual, the dealer doesn't know jack-shit so he is guessing.........and a
piss poor guess too, I think.
My guess is ONE to get it "limpable" (20-30 lbs) and TWO to get it back up
to 40.............assuming that the original hole is plugged or very tiny.

This depends, to a degree, on what size cartridges you are using and
if you need enough pressure seat the bead or simply reinflate the
tire.

You can get the cartridges in at least four common sizes: 12g, 16g, 25
and 40g.

My only real experience is with dirt bike tires. I'm running a 4.00/18
tubeless IRC Trials tire (with a tube of course). It can take 3-4 12g
cartridges to get the bead seated (dry, trailside repair) at somewhere
around 30-35psi. I only run 10psi while riding, so I have to let out
most of it. Am I adding the Global Warming with this blatent discharge
of CO2? <G>

With the bead seated it only takes one 12g cartridge to get me up to
about 20 psi.

If you are looking for an inflator to carry along with you, be sure
whatever you get will accept the standard, non-threaded cartridges,
they are much cheaper than the threaded ones.

DJ

[IdaSpode]

Post by IdaSpode
On Mon, 17 Sep 2007 22:03:49 GMT, "Ken Abrams"

Post by Ken Abrams

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.

As usual, the dealer doesn't know jack-shit so he is guessing.........and a
piss poor guess too, I think.
My guess is ONE to get it "limpable" (20-30 lbs) and TWO to get it back up
to 40.............assuming that the original hole is plugged or very tiny.

This depends, to a degree, on what size cartridges you are using and
if you need enough pressure seat the bead or simply reinflate the
tire.

Oops, guess I should have paid more attention to the subject line,
where it sez "16 gram".

DJ

[Wudsracer]

************************************************

Post by IdaSpode
On Mon, 17 Sep 2007 22:03:49 GMT, "Ken Abrams"

Post by Ken Abrams

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.

As usual, the dealer doesn't know jack-shit so he is guessing.........and a
piss poor guess too, I think.
My guess is ONE to get it "limpable" (20-30 lbs) and TWO to get it back up
to 40.............assuming that the original hole is plugged or very tiny.

This depends, to a degree, on what size cartridges you are using and
if you need enough pressure seat the bead or simply reinflate the
tire.
You can get the cartridges in at least four common sizes: 12g, 16g, 25
and 40g.
My only real experience is with dirt bike tires. I'm running a 4.00/18
tubeless IRC Trials tire (with a tube of course). It can take 3-4 12g
cartridges to get the bead seated (dry, trailside repair) at somewhere
around 30-35psi. I only run 10psi while riding, so I have to let out
most of it. Am I adding the Global Warming with this blatent discharge
of CO2? <G>
With the bead seated it only takes one 12g cartridge to get me up to
about 20 psi.
If you are looking for an inflator to carry along with you, be sure
whatever you get will accept the standard, non-threaded cartridges,
they are much cheaper than the threaded ones.
DJ

**********************************

Riding (dirt) around here, I just don't worry about it.
My rimlocks will hold the tire on the rim long enough to get me back
to the truck (where I have a $6.97 WalMart 12v air compressor.

Riding in Idaho with DJ, I make sure someone in the group has an
inflator. <VBG>

My favorite is the CO2 inflator which is also a pump. These are very
useful, and i have inflated a tire using the pump part of them. The
pump put up enough pressure to finish seating the bead on a rear
knobby tire, after using a CO2 cartridge to get started good.

Good Riding & Tire Inflating to You!




Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF

[Mark Olson]

Post by Ken Abrams

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.

As usual, the dealer doesn't know jack-shit so he is guessing.........and a
piss poor guess too, I think.
My guess is ONE to get it "limpable" (20-30 lbs) and TWO to get it back up
to 40.............assuming that the original hole is plugged or very tiny.

Ken, have you ever used CO2 cartridges to inflate a motorcycle tire?
If not, why is your guess any better than the dealer's guess?

http://www.mcnews.com/mcn/features/Mini%2012%20Volt%20Compressor.pdf

"AS WE LEARNED from Don Smith's comparison of tire repair and inflation
kits, CO2 bottles make a relatively poor choice for emergency tire
inflating as you need to carry so many of the darn things to actually
inflate a tire, plus, they are expensive."

I don't have a link to the MCN article that compared the CO2 cartridges
to the various pumps, but I remember reading it and taking MCN's advice
to heart. I doubt that when MCN says it takes "so many of the darn things
to actually inflate a tire" that two of them would fully inflate a
180-17 tire to 40psi.

So, I have a mini 12V air compressor in my toolkit, it does the trick,
it was less than $10 and it takes up no more space or weight than a
handful of CO2 cartridges. I've had occasion to use it a couple of times,
including pumping up an almost completely flat car tire. The pump got
hot but it did the job.

[The Older Gentleman]

Post by Mark Olson
So, I have a mini 12V air compressor in my toolkit, it does the trick,
it was less than $10 and it takes up no more space or weight than a
handful of CO2 cartridges.

Genius idea.

I'm off to the shops to get one today.

[Mark Olson]

Post by The Older Gentleman

Post by Mark Olson
So, I have a mini 12V air compressor in my toolkit, it does the trick,
it was less than $10 and it takes up no more space or weight than a
handful of CO2 cartridges.

Genius idea.
I'm off to the shops to get one today.

Be aware that some of them, probably most of them, are utterly
shit and you are rolling the dice hoping to get a half decent
one that will last through inflating more than one or two tires.
I'm on my 2nd one after the first lived through a fair number
of flats on the car before being relegated to bike duty.

Also, you may want to fashion some sort of minimal shroud
around the big end/reduction gears so that you can safely let
the pump lie on the ground, it gets tedious holding it aloft
while waiting for a tire to inflate.

Also if SWMBO volunteers to hold it while you are inflating
her Ninjette tire, tell her to keep that shop rag away from
the gears, thank goodness for spare fuses.

[Ken Abrams]

Post by Mark Olson
Ken, have you ever used CO2 cartridges to inflate a motorcycle tire?
If not, why is your guess any better than the dealer's guess?

It isn't any better......without qualification, that is
.
I hadn't considered seating the bead on a tubeless application.
My only experience was with a patched tube.

Sounds like those with experience in that arena much prefer a
mini-compressor but even with that, I can't help but wonder if getting the
bead seated might be more a matter of luck than skill, as I doubt that the
air flow would really help much.

[Mark Olson]

Post by Ken Abrams
I hadn't considered seating the bead on a tubeless application.
My only experience was with a patched tube.
Sounds like those with experience in that arena much prefer a
mini-compressor but even with that, I can't help but wonder if getting the
bead seated might be more a matter of luck than skill, as I doubt that the
air flow would really help much.

The mini compressors are useless for seating a tubeless tire bead. There
just isn't enough airflow. It's possible that a large CO2 cartridge might
have an advantage there, but since I've never used one I won't speculate.
To be clear, the one guy who did talk about seating a bead with a CO2
cartridge was talking about a tubed tire, where a mini compressor would
work just as well. To seat a tubeless tire once the tire's come off, you
need to either wrap the tire's circumference with a band or rope and/or
have a pretty decent amount of airflow to overcome the leakage. I managed
it one time with the wheel in place on my GL1200 after a flat, but it
was a bastard of a job with three guys working on it simultaneously, and
we had a proper air compressor with a good sized tank.

[Ron Gibson]

Post by Ken Abrams

Post by M. MacDonald
Dealer says a lot, maybe 7-8 cylinders.

As usual, the dealer doesn't know jack-shit so he is guessing.........and
a piss poor guess too, I think.
My guess is ONE to get it "limpable" (20-30 lbs) and TWO to get it back up
to 40.............assuming that the original hole is plugged or very tiny.

Yeah you'd think the dealer would come off the few bucks the things cost
him and inflate a tire for a real world test which is certainly faster
than calculating the answer.

[B. Peg]

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.

Dealer might be right. I had to use the one that came with a BMW and three
didn't even make a dent in it. Of course, some leaked out of both the the
stringy stuff they call a plug and some more from the funky adapter for the
C02 chuck. Ended up needing to use a can of Inflate-a-Flat in a larger
spray-type can and tire still wasn't fully up and wobbly.

I believe after the ordeal those C02 things were designed for bicycle tires
and not motorcycle tires. They say that one 16 gramer can inflate a
'Mountian Bike (i.e. bicycle) Tire" to about 40psi. That's going to be a
lot of motorcycle tires.

Get a compressor like maybe the "Slime" one. It's volume would amount to a
dozen of those cylinders and you'd still have fudging room should it still
leak. It doesn't cost any more than a dozen of those C02 things.

B~

[Rick Cortese]

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.
Anyone need to use one?
Tia.
Mack

My excuse is this is a technology group. Been a while so double check
for mistakes.

CO2 => MW of 44g/mole.

1 mole of gas at STP is 22.4 liters => 16g will make 8.1 liters. Imagine
something like an empty garbage bag that wouldn't increase the pressure
the gas was under when you inflated it to hold the gas. STP is standard
temp and 1 atm of pressure. If you don't have a feel for liters, ~2 gals
of dead air.

Gases volume are inversely proportional to pressure. Of course it
depends on how big of a tire you are inflating but take 4 liters as an
model. The first cylinder will inflate it to 15 lbs: 8 liters at 1
atmosphere squeezed into a 4 liter space => two atmospheres or ~30 PSI
or 15 lbs greater/differential then outside.

From there it should go up 30 PSI for every extra cylinder. That is,
when you have 2 => 16 liters in 4 liters of space or 4 atms or 60 psi or
45 psi greater then sea level pressure.

As some people have pointed out, the volumes for some tires is much
greater then 4 liters and it would require proportionately more
cylinders to get to a usable pressure. I can't see someone on a cruiser
finding them useful.

On the other hand, those little Mickey Mouse pumps like Mark talks about
are useful to a point. I mean their gages may go to 200 PSI but you are
lucky to get 20 PSI out of the one I own. The one good thing about the
CO2 cylinders is they will go to something like 180 PSI. If you can
afford the room/weight, you may want to carry the pump for getting the
tire up to a marginal inflation level and the cylinders to a safe
operating level.

Rick

[Ron Gibson]

Post by Rick Cortese
My excuse is this is a technology group. Been a while so double check
for mistakes.

Use the Ideal Gas Law...PV=nRT

http://wiki.answers.com/Q/What_is_the_Ideal_Gas_Law

You'll have to do some dimensional conversions especially for the cans
and determine the volume of the tire. Maybe not though because some
values may cancel out. Might be able to use the form...

P(1)*V(1)/P(2)*V(2)=N(1)*T1(1)/N(2)*T(2)

The R cancels and off the top of my head so should the T's but unless I
start crunching numbers I can't be sure. My specialty is HVAC so I don't
use the Ideal Gas Law a lot anymore but it should work.

You could use the volume of a torus to approximate the volume of the
tire...

The specific formula is here...

http://en.wikipedia.org/wiki/Torus#Geometry

General info...

http://en.wikipedia.org/wiki/Torus

Again off the top of my head that approximation should get you within
90%+ of the true tire volume. If you're a math whiz kid you can refine
the volume further after making the first approximation. But I'd just
but one extra can to cover myself. It's too much work refining the volume
numbers further unless I'm getting paid :-)

[Rick Cortese]

Post by Ron Gibson

Post by Rick Cortese
My excuse is this is a technology group. Been a while so double check
for mistakes.

Use the Ideal Gas Law...PV=nRT

I did. The 22.4 liters/mole is the derived part from n and R so the only
thing left is atmospheric pressure and temperature which falls out most
places you can operate a motorcycle i.e. ~sea level and 20C.
<snip>

Post by Ron Gibson
You'll have to do some dimensional conversions especially for the cans
and determine the volume of the tire. Maybe not though because some
values may cancel out. Might be able to use the form...

Not in this particular case because the CO2 in the cylinder is probably
liquid/gas. The 16 grams is the only thing you can count on for
quantity. I should go to the handbook of chemistry and physics to make
sure about my 180 PSI at ~20C but feeling a bit lazy.

Rick

[Ron Gibson]

Post by Rick Cortese
Not in this particular case because the CO2 in the cylinder is probably
liquid/gas. The 16 grams is the only thing you can count on for quantity.
I should go to the handbook of chemistry and physics to make sure about my
180 PSI at ~20C but feeling a bit lazy.

Yeah, I know what you mean.

Did the link on the volume of the torus help? If you use that what I'd
do is calculate the volume for a torus that completely enclosed the outer
dimensions of the tire and wheel, which would be a bit too big. Then I'd
calculate the value of the largest torus that would fit inside the the
tire and wheel.

Then your true volume would have to be between the two values. I'd take
a simple average of the two volumes and that ought to be awfully close
to the true volume.

Another sneaky method would be to fill a tub with water and have an
overflow tray under it. Submerge the mounted tire in water and measure
how much water overflowed. Then do the same for just the wheel.

Then the gas volume would be = Volume Full Tire - Volume of the wheel

If you really want to be precise immerse just the tire alone and
subtract that volume from what you got above. If you are careful that
should be accurate within 1%-3%

That's a lot of work though.

[The Older Gentleman]

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.
Anyone need to use one?

Not yet. I think BMW packs two or maybe three in their puncture kits
(I'd have to check), and so I'd assumer they know the reality, and pack
that many.

[Rob Kleinschmidt]

Post by M. MacDonald
Regarding those CO2 tire inflator kits, anyone know how many cylinders it
takes to get a rear 180x70x17 tire back up to 40 psi?
Dealer says a lot, maybe 7-8 cylinders.
Anyone need to use one?

I don't think you need 7-8 cylinders, but a pump
would be less bulky if you did.

I normally use a $10 Walmart tire inflator with
the plastic housing and fan removed. At a rally
last weekend, I saw the same $10 Walmart pump
reworked a little more elegantly than I'd bothered
with selling for ~ $45.

Wire an ordinary lighter socket into the electrics
to provide an outlet to plug the pump into. Also
very useful for quickly inflating your air mattress
at night when you pitch camp.

[Ron Gibson]

Post by M. MacDonald
Dealer says a lot, maybe 7-8 cylinders.

I don't think you need 7-8 cylinders, but a pump would be less bulky if
you did.

I use a regular Kmart bicycle pump for 110/90-18. Might take a bit of
time pumping one up that was completely flat but I can go from 30 to 40
PSI in about 3-4 minutes or about 8-10 pump strokes.