Nitrogen in tires - Page 3 - PeachParts Mercedes-Benz Forum

eec564 · #31 08-07-2006, 03:58 PM

It's not the weight of the nitrogen, or anything specific in the nitrogen itself. It's the lack of moisture inside the tire that makes a difference. When tires get hot, the moisture turns to steam, and the pressure inside the tire increases a LOT. This happens most noticeabally on preformace cars and racers whos brakes heat the wheels significantly (since they're bolted together). Having pure nitrogen in tires contributes to a more stable (and very predictable) pressure across different tire temps. This COULD in a consumer car lead to an increase in milage, but it would higly depend on driving conditions. Anyone driving their car hard enough to notice would most likely already be using nitrogen. The one added benifit for a consumer of using nitrogen rather then air is tires rot a LOT less without moisture inside of them. When parked, that moisture sits on the bottom of the tire and rots out the inside, where you can't see it until the tire completely blows out, not just goes flat. This happens even if your car is stored inside for long periods. If your tire was filled from an aircompressor with a lot of moisture in it, leaving the tire to sit for as little as six months could rot it out, it happened to me.

Kestas · #32 08-07-2006, 05:46 PM

If moisture is the issue, then we could essentially DIY most of the same result by purging the tires in Michigan with air during January, when the dew points are near 0°F. That's pretty dry!

As far as gaining 2 mpg... if this was true, cars would be leaving the factory that way, unless EPA rates the car mileage on some kind of dyno test.

Jeremy5848 · #33 08-07-2006, 06:31 PM

Quote:

Originally Posted by Kestas

As far as gaining 2 mpg... if this was true, cars would be leaving the factory that way, unless EPA rates the car mileage on some kind of dyno test.

True. The claimed mileage gain is a self-fulfilling prophecy, probably due to
(a) checking and maintaining tire pressure regularly, a good thing for all of us to do
(b) driving "carefully" (perhaps even without realizing it) and leaving the lead shoe at home
(c) otherwise keeping the car in a well-maintained condition, again perhaps unconsciously

The water that often contaminates "inexpensive" compressed air is definitely a problem for users such as NASCAR and the commercial airlines. In a race car, tire pressure is critical; moisture in the tire will turn to water vapor and raise the pressure. In an aircraft tire, the same moisure will freeze at altitude, putting the tire out of balance. You don't want that when you land at 170 MPH.

Finally, water and oxygen at high pressure and temperature cannot be good for tires (or anything else). Both water and oxygen are highly corrosive, especially in conditions above STP.

For us average Joes, a question might be, how long does this supposed accelerated rotting process take? If one drives enough to wear down the tread in two years, does it really matter what is inside the tire?

eec564 · #34 08-07-2006, 06:35 PM

Well, you'd have to completely drain your aircompressor of any moisture in the bottom and fill it when the humidity is really really low, but that would work pretty well. Remember that even on the dryest of days the humidity is 10-20%, and that always gets compounded by aircompressors. As air leaves the compressors, the pressure drop causes the condensation in the tank to become airborne and leave via your air hose. Dry nitrogen (pure nitrogen is by deffinition dry) is a perfect 0% moisture content. Again, for the 1-2mpg, I'm skeptical, but truth is stranger then fiction.

ConnClark · #35 08-07-2006, 06:35 PM

You might get an aditional 2mpg with a smart car, but I don't think your going to get serious return on your investment on your average car. Unless you have a bus or 18 wheeler where rolling resistance is a much bigger factor its not going to save you much money.

vahe · #36 08-07-2006, 06:53 PM

Most tire places apply a nice little dose of soapy water to the rim prior to installing the new tire. That stuff stays trapped inside the tire for good, with or without Nitrogen, if moisture is bad for your tires, you will have it no matter what.

Vahe
240D/77 350K

Robert W. Roe · #37 07-06-2018, 11:59 PM

My wife's Mazda3 was sold with nitrogen in the tires.

I spoke with a service advisor at a Mazda dealership today.

I asked the guy what the deal was, since I had to top off her tire pressures the other night.

He said that they actually pull a vacuum before inflating with nitrogen.

That "should" get rid of any water vapor in the tires, similar to pulling a vacuum in AC lines, I would think.

He wasn't sure of the cost but it sounded substantial from what he said: "$79 or $99."

I did check into the cost of a tank if I bought one from a local gas distributor; $165 would buy me a 60 cubic foot tank filled with dry nitrogen, which is about 3 feet tall, and would cost $37 to refill.

That doesn't include the regulator (I don't think) but eBay has several choices.

97 SL320 · #38 07-07-2018, 10:28 AM

Nitrogen filled tires are somewhat of a placebo, there is a benefit but the cost is rather high for an on the road car.

Race car teams started to use nitrogen because high pressure nitrogen bottles are convenient where compressed air is not available. For a racing application, dry gas is critical in keeping tire pressures at expected levels. ( Water throws off the expansion curve )

Nitrogen is a larger molecule so tire leak rates will be lower but, if a tire is filled with regular air, eventually you will end up with a higher concentration of nitrogen / lower leak rate as the oxygen and other gasses leak out.

As an experiment, I used bottled CO2 to fill a slightly leaky tire, as the CO2 concentration rose, so did the frequency of refilling.

Regular dry air will be just fine.

Hardus1 · #39 11-22-2021, 10:39 AM

I keep hearing about nitrogen-filled tires lately. It costs about $30 to fill all four tires. Is it just me or is this a big pile of crock? (If you don't care about this, the person looking after the car(s) in your home may.)

Their advertising seems to focus around four points:

Tire pressure retention over time

Tire pressure consistency with temperature change

Reduction of rim corrosion

Race cars and airplanes use them
I'm going to look at each of these points, then have a quick boo at the economics of it.

Tire Pressure Retention Over Time https://showbox.tools/
The first fact presented in the advertising is that a nitrogen molecule is bigger than an oxygen molecule, so less of it will leak through your tire. I hate to admit that I had to check the periodic table for this, but... uhhh... how do I say this? Oxygen is actually bigger than nitrogen. Seriously. Oxygen has 8 protons, and nitrogen has 7. The molecular mass of an oxygen molecule is 32.00, versus nitrogen's 28.02. The ads start with a flat-out lie. The consumer agencies should probably look into that. In any case... epic fail.

Kestas · #40 11-22-2021, 11:03 AM

I'm guessing rim corrosion works from outside in. It's a big problem in the rust belt.

Airplanes use them because it is easier to wheel a nitrogen tank to the airplane to fill 300 psi than using shop air.

oldsinner111 · #41 11-23-2021, 08:23 AM

I use hydrogen, knocks 1500 pounds off a s class weight

Texasgeezer · #42 01-07-2022, 08:57 PM

Based on what I've read, it does make sense to use nitrogen when available for no or minimal cost.

1. reduced moisture in tire reduces chance of pressure increase and reduces corrosion of rims and steel strands in tire rubber

2. Nitrogen passes through the tire about 1/3 slower than oxygen

3. Staying close to desired pressure is better with nitrogen. This reduces flexing of sidewall and premature tire failure.

4. Reduces dry rotting inside of tire due to reduced oxygen and moisture

This site promotes the use of nitrogen and provides links:

https://www.getnitrogen.org/deepscience/

C.Doner · #43 06-14-2022, 01:27 PM

[/QUOTE]Tire Pressure Retention Over Time https://showbox.tools/
The first fact presented in the advertising is that a nitrogen molecule is bigger than an oxygen molecule, so less of it will leak through your tire. I hate to admit that I had to check the periodic table for this, but... uhhh... how do I say this? Oxygen is actually bigger than nitrogen. Seriously. Oxygen has 8 protons, and nitrogen has 7. The molecular mass of an oxygen molecule is 32.00, versus nitrogen's 28.02. The ads start with a flat-out lie. The consumer agencies should probably look into that. In any case... epic fail.[/QUOTE]
This is false. The N2 molecule has more volume than the O2 molecule. Periodic trends are learned in basic chemistry courses.