Crazy Bimmer

Stupid question....


Say you have a wheel thats 24lbs and a tire thats 26lbs, how much will that weigh once its mounted together with say 32psi of air?

Dan Martin

You'd need to know the inside volume of the tire to figure that out...

bkzjimmy

use helium.

Ashburner

use hydrogen

INSPIRE 32V

iTrader: (1)

use nothing lol

sipark

Doesn't it depend on temperature, altitude and volume?

In other words,

FiveLiterCheater

^^ What sipark said, it varies

1killercls

I got Nitrogen in my tires.

trancemission

man i wouldnt think it would be enough to make any difference.

but I would go with what killer said. dry nitrogen is the way to go....

fdl

Dan Martin

I get a custom blend in my tires:
Nitrogen 78.084 %
Oxygen 20.9476 %
Argon 0.934 %
Carbon Dioxide 0.0314 %
Neon 0.001818 %
Methane 0.0002 %
Helium 0.000524 %
Krypton 0.000114 %
Hydrogen 0.00005 %
Xenon 0.0000087 %

CGTSX2004

iTrader: (1)

Whiskers

GreenMonster

My WAG ?? not much to really make a difference...

and temperature... and the molar mass of air... use the ideal gas law...

Wsteven would probably be able to help figure it out...

Google turns up this: http://www.madsci.org/posts/archives...5256.Ch.r.html

Crazy Bimmer

Ouch my head.

Ill just wait till the wheels are mounted and put them on a scale.

Crazy Bimmer

Main reason i ask is that i just sold my DPE wheels and they weighed 60lbs

How can that be? Tire was 27lbs so no way my rim was close to 33lbs?

good thing my new wheels are only 18 lbs without tire

charliemike

Umm dude those things were huge

BTW, at 60 degrees F "air" weights about 7.636lbs per cubic foot.

Or something.

Math is hard!

BENDER08

Dan Martin

I think you might have got your decimals mixed up... At sea level, it's about 0.08 pounds per cubic foot.

charliemike

I ain't know! I just do what the Man says

Seriously, weighing air is an entirely theoretical exercise in futility if you ask me

coconut

PV=nRT

FiveLiterCheater

33LBS?! No freakin way....aren't they forged? My 2-piece Rays weigh like 24lb, and theyre 19x9

DPE's are supposed to be light...i'm guessing they're around 23-25lbs for 19"

Will Y.

Did you weigh the wheels/tires or the fully-packed box?

Also, remember that those wheel balancing weights are made of LEAD, so they will add some weight (but I don't think it would be more than 5 lbs.)

Osamu

using their volume calculation and ideal gas law, i got roughly 75g. I'm not sure I did this right though. It's been like 4 years since I've even looked at the ideal gas law. I used 32psi (2.18atm), 29L, 298K, 0.0821 L·atm·K-1·mol-1, and 29g/mol for air. I guess air isn't technically an ideal gas so that might be a problem.

GreenMonster

Yeah, which is why the weight of the air shouldn't matter... normal pressure is 14.7 psi and a tire can't hold more than a few cubic feet of air...

Jesal, PM Wstevens... he does this kinda shit for a living... and since he's part of the 335 club, I'm sure he'll help out

NSXNEXT

iTrader: (2)

Were you standing on the scale?

Crazy Bimmer

Dont make fun of my taco bell disease.

Bearcat94

Cool. I've heard Nitrogen is the shizzle.



How much does Nitrogen weigh (in tires at 32psi)?

Dan Martin

Don't forget that normal air is 78% nitrogen. Pure nitrogen has a density of 1.251g/L at standard temperature and pressure, whereas air has a density of 1.292g/L. In other words, if you fart before you leave, you'll save more weight than you would if you filled your tires with nitrogen.

Brandon24pdx

15 lbs of unsprung weight will make a big difference in handling.

trancemission

we use it in all aircraft tire applications. mainly because nitrogen doesn't support combustion. Im sure there are other reasons...

I use it in mine simply because its available...

CashMoney

just wondering tho where i would post on a 1997 2.5tl parts car

TSXey

from http://en.wikipedia.org/wiki/Tire:

Aircraft tires are usually inflated with nitrogen gas in order to minimize the expansion and contraction due to the extreme changes in temperature experienced during flight. Dry nitrogen expands at the same rate as other dry atmospheric gases, but common compressed air sources may contain some moisture, which would increase the expansion rate with temperature. Aircraft tires generally operate at high pressures, up to 200 psi (13.8 bar) for airliners and higher for business jets.

Aircraft tires also include heat fuses, which melt when a certain temperature is reached. Tires often overheat if maximum braking is applied during a rejected takeoff or an emergency landing. The fuses provide a safer failure mode, since the tire will no longer explode when overheated, but deflate in a controlled way, thus minimizing damage to aircraft or injury to people on the ground.

The main purpose of requiring that an inert gas, such as nitrogen, be used instead of air, for inflation of tires on certain transport category airplanes is prompted by at least three cases in which the oxygen in air-filled tires combined with volatile gases given off by a severely overheated tire and exploded upon reaching autoignition temperature. The use of an inert gas for tire inflation will eliminate the possibility of a tire explosion. Federal Aviation Administration 14 CFR Part 25 [Docket No. 26147; Notice No. 90-7] RIN 2120-AD37 Use of Nitrogen or Other Inert Gas for Tire Inflation in Lieu of Air

PS: VERY funny album

Costco

Where do you guys get nitrogen fills at? Or is there some sort of machine and tank I can buy and do it myself?

TSXey

what's your screen name again???? As far as I've seen, Costco fills tires with nitrogen. Around here, most of the "better" tire service places use nitrogen, some charge extra for it, others only use nitrogen.