Mercedes-Benz Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #1
Has anybody else elected to use Nitrogen in your tires? Nascar runs it so the pressure won't change with temperature and easier to measure in smaller increments, .5 lb, etc. I use Nitrofill in all my vehicles and get great luck with virtually no change in pressure, excellent roadside assistance as a part and cheap annual fees.
 

·
Registered
Joined
·
164 Posts
Air is approximately 80% nitrogen. I fail to see how changing 20% of what goes into the tire will make any significant difference. Bill
 

·
Registered
Joined
·
15 Posts
Discussion Starter #4
Outside of the racetrack nitrogen is a waste of money.
Let's assume that is true, the roadside assistance is worth the price of the plan. Their provision is better than AAA Texas(free towing more distance) and cheaper too. I have used their services twice now, blown tire on interstate hwy, they sent a wrecker in 30 minutes and he changed and got me on the road again. I have a very painful chronic back condition and could not handle the 20" spare tire down and off.

later lost my alternator and battery died quickly, could not make it home, they sent a wrecker (different car) and took me home where I could make the change. both of these free of charge

Now, back to the nitrogen, it's comforting to not have to worry about tire pressure every time the weather changes. With all the TPMS systems out there today, you don't have a perpetual yellow light on your dash.

the last argument is the air we breathe is 80% nitrogen anyway, yes but the molecules are much larger and are much less permeable and tires stay properly inflated a higher % of the time, reducing wear, increasing mpg and reducing maintenance time finding a compressor to air them up. In my first vehicle to use it, the pressure changed 1 lb in 1 tire over 18 months.

I don't make a dime off these guys, I'm purely a happy customer. not trying to "sell" anything, just sharing my experience. ;)
 

·
Registered
Joined
·
15 Posts
Discussion Starter #5
Sorry, one more point. My wife travels a bit and she has this roadside assistance for anything when we can't find me. lockout, dead battery, flat tire, out of gas, etc. which is very comforting to her. She loves it and you know the old saving, "if momma ain't happy, ain't nobody happy !!" Well the opposite is also true, if momma happy, everybody happy. :thumbsup:
 

·
Registered
Joined
·
164 Posts
OK, just so that you see where I'm coming from, I'm a retired chemistry prof. Nitrogen is no more resistant to pressure changes than any other gas. In fact, there is a thing know as the "Ideal Gas Law." This states that PV=nRT, where P is for pressure, V is volume, n is the amount of gas in a unit known as "mols," R is a constant and T is temperature. EVERY gas changes pressure with changes in temperature, and in almost exactly the same amount!

Now, on the matter of size of the molecules, nitrogen gas MIGHT be a slight bit larger than oxygen, but according to my quick calculations, the difference is 0.0022%. I'm sure that I can't detect 0.0022% difference in anything. If you are happy with this service, by all means use it, but to people like me it appears to be a large waste of money. Bill
 

·
Registered
2010 C200 CGI /W203/SLK230/W202/230E/280SE
Joined
·
3,301 Posts
If Teasac reckons that he loses only 1lb in 18 mths and he is not paying an extraordinary amount for the service, that seems fair enough, despite the size of the Nitrogen molecules?

That's at least 68 fewer tyre top ups with the pressure gauge, brake dust in your eyes and on your fingers (not to mention how much less tyre wear, because most of us top up when our tyres are a bit on the low side)

Oberoi
 

·
Premium Member
107, 115, 116, 123, 124, 126
Joined
·
5,924 Posts
In the real world, I experience less pressure fluctuations at a track day event in a Porsche pushed to the max if nitrogen is used. Off the track, in everyday driving, no difference.

The roadside assistance angle may be worth it. I get free roadside assistance from Nationwide and Mercedes anyway, however. AAA is worthless in my recent experience. Keys locked in car, crying baby, and they put me on hold. After 20 minutes I hung up and called a locksmith directly.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #9 (Edited)
OK, just so that you see where I'm coming from, I'm a retired chemistry prof. Nitrogen is no more resistant to pressure changes than any other gas. In fact, there is a thing know as the "Ideal Gas Law." This states that PV=nRT, where P is for pressure, V is volume, n is the amount of gas in a unit known as "mols," R is a constant and T is temperature. EVERY gas changes pressure with changes in temperature, and in almost exactly the same amount!

Now, on the matter of size of the molecules, nitrogen gas MIGHT be a slight bit larger than oxygen, but according to my quick calculations, the difference is 0.0022%. I'm sure that I can't detect 0.0022% difference in anything. If you are happy with this service, by all means use it, but to people like me it appears to be a large waste of money. Bill
With all due respect there Prof, I certainly have to surrender to your expertise :surrender: (not being a smart azz), seriously, I can't compete. what I can tell you is for $39.95 per year, I get virtual maintenance free tire inflation (even if I can't explain how); roadside assistance second to none and so far, I believe better tire wear. I'm using it my third vehicle, none of them alike the others, (i.e. full size pickup, BMW suv, now in my C240.

I certainly can't dispute your chemistry laws but how do you explain that NASCAR gets such steady performance in their tires with all the temperature increase they get on the track?? Not trying to debate, trying to learn, how does it work??
 

·
Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
Joined
·
19,447 Posts
There are two things better about nitrogen tire inflation over standard atmospheric air inflation. First, tires filled with nitrogen hold their pressure longer. Second, nitrogen inflation systems filter out common contaminates such as oils and moisture which can cause greater pressure variances over temperature ranges. The first advantage is due to nitrogen molecules being larger than oxygen molecules which mean they don't find their way through the tire's rubber molecules as easily. Of course the latter advantage could be overcome with air if it were properly filtered, but the systems used to do this can very easily produce nearly pure nitrogen, so with it's advantage over oxygen, why not just use the larger molecules? Personally, I wouldn't pay anything extra for nitrogen, but if it's free, then go for it. Mine is free as I get my tires services at Costco. Now, if I could just get them to stop replacing my fancy valve caps with cheap green plastic ones...
 

·
Registered
Joined
·
164 Posts
With all due respect there Prof, I certainly have to surrender to your expertise :surrender: (not being a smart azz), seriously, I can't compete. what I can tell you is for $39.95 per year, I get virtual maintenance free tire inflation (even if I can't explain how); roadside assistance second to none and so far, I believe better tire wear. I'm using it my third vehicle, none of them alike the others, (i.e. full size pickup, BMW suv, now in my C240.

I certainly can't dispute your chemistry laws but how do you explain that NASCAR gets such steady performance in their tires with all the temperature increase they get on the track?? Not trying to debate, trying to learn, how does it work??
You asked a fair question and I will try to explain what I can. As a scientist, my first question was whether your assertions about NASCAR using nitrogen and that tires inflated with nitrogen held pressure longer. I found both of those to be true. At this point I am only ready to explain why inflating with nitrogen benefits race cars. It came to me when I read the web page of one of the nitrogen suppliers. They stated that their nitrogen was DRY. When you put compressed air into your tires, you are adding the 78% nitrogen, approx 21 % oxygen and trace amounts of carbon dioxide and other gases. But, you are also adding an amount of water which depends on the temperature of the air and the relative humidity of the air. Everything which you add here, except the water, obeys the ideal gas law. If you inflate a tire with dry gas, and it doesn't matter much which one, to 30 PSI at 70 degrees F. and then heat the tire to 212 degrees F, the pressure will increase to about 38 PSI, or an increase of about 25%. Water, on the other hand does not obey the ideal gas law in this temperature range because some of the water can still be in the liquid state. The pressure exerted by the water will increase forty times on heating from 70 to 212, and the total pressure of the water will depend on how much water there is in the air in tire, which depends on the temperature and humidity at the time of inflation. Going with a dry gas eliminates this uncertainty. Dry air should work just as well from this point of view. That is my best guess as to why race cars use the dry nitrogen. Most of us don't operate our vehicles in such a manner that our tires heat up that much. I'm still trying to come up with a good explanation as to why Nitrogen doesn't leak out of tires as fast as air does. Bill
 

·
Registered
Joined
·
15 Posts
Discussion Starter #12
There are two things better about nitrogen tire inflation over standard atmospheric air inflation. First, tires filled with nitrogen hold their pressure longer. Second, nitrogen inflation systems filter out common contaminates such as oils and moisture which can cause greater pressure variances over temperature ranges. The first advantage is due to nitrogen molecules being larger than oxygen molecules which mean they don't find their way through the tire's rubber molecules as easily. Of course the latter advantage could be overcome with air if it were properly filtered, but the systems used to do this can very easily produce nearly pure nitrogen, so with it's advantage over oxygen, why not just use the larger molecules? Personally, I wouldn't pay anything extra for nitrogen, but if it's free, then go for it. Mine is free as I get my tires services at Costco. Now, if I could just get them to stop replacing my fancy valve caps with cheap green plastic ones...
thanks, I appreciate sharing your thoughts and truths about this whole matter. My only encouragement to you is while the nitrogen is FREE at Costco, don't overlook the roadside package that comes with Nitrofill. I have used it for 3 years and really "used" it with breakdowns, blown tire and they also provide $100 reimbursement for road hazard blown tire. AAA is higher and doesn't provide what they do. but I rest my case. it's another of those very personal choices.
 

·
Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
Joined
·
19,447 Posts
Hmm, I've never heard of Nitrofill. I have both AAA Plus/Gold and MBZ Roadside Assist at my disposal. AAA in our area is very good and also provides other discounts (hotels, restaurants, etc.). Oh, and I think our car insurance policy also has a roadside assistance and towing provision. I like Costco not necessarily because of their nitrogen, but because they have great tire prices and excellent service. I like the fact that they actually hand torque the lugs. And when they scratched two of my rims, they bent over back wards to make sure they took care of it to my complete satisfaction.
 

·
Registered
Joined
·
164 Posts
I've finished my research on the sizes of the nitrogen molecule and the oxygen molecule, and although I have seen many times on sites discussing using nitrogen to inflate tires, that nitrogen is larger than the oxygen molecule, that just is not true. Using data from reputable sources such as the "Handbook of Chemistry and Physics" and university sources, I found that the nitrogen molecule is a rod-shaped molecule which is 218 picometers long with the cross-section diameter of the rod being 108 picometers. The oxygen molecule is also rod-shaped and is 235 picometers long with the cross-section diameter being 114 picometers. So, the volume of the oxygen molecule is approximately 20% greater than the volume of the nitrogen molecule. So, if nitrogen is not bigger than oxygen, then why does oxygen pass through the rubber faster? I still don't have an answer for that one, but I have found that some other gasses which are larger than oxygen pass through rubber even faster than oxygen does. One of these is carbon dioxide. It is more than 50% larger than oxygen, yet it passes through the various types of rubber at rates of four to ten times as fast as does oxygen. Then there are the hydrocarbon gasses methane, propane and butane. Methane is the smallest, propane is next in this series, and butane is the biggest, but for every type of rubber in the table, the larger the molecule,, the faster it passed through the rubber. One last thought. If one inflates their tires with air and after they have lost some pressure, apparently because of the oxygen escaping preferentially through the rubber, and you re-inflate them with air, and repeat this process several times, shouldn't you end up with almost pure nitrogen in the tires? Then you should never have to inflate them again! For every problem there is an easy answer, but that does not mean that it is the right answer. Bill
 

·
Premium Member
107, 115, 116, 123, 124, 126
Joined
·
5,924 Posts
Great research Bill, thanks. I don't know about the nitrogen not leaking as fast as the regular air, but I have observed that the pressure doesn't fluctuate as much at the track under extreme conditions. The Porsche tire pressure monitors are very sensitive and send scary messages when at the track. Nitrogen seemed to calm them down a bit.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #16
Hmm, I've never heard of Nitrofill. I have both AAA Plus/Gold and MBZ Roadside Assist at my disposal. AAA in our area is very good and also provides other discounts (hotels, restaurants, etc.). Oh, and I think our car insurance policy also has a roadside assistance and towing provision. I like Costco not necessarily because of their nitrogen, but because they have great tire prices and excellent service. I like the fact that they actually hand torque the lugs. And when they scratched two of my rims, they bent over back wards to make sure they took care of it to my complete satisfaction.
You certainly don't have any incentive to look into Nitrofill with as much "other" roadside coverage as you have. I was discussing this whole nitrogen thing over lunch today with our local muscle car expert and he says it's all a bunch of hooey. I'm not trying to CONVERT anybody and don't make a dime off this stuff so it's certainly no hair off my head (what little there is left). I have shared MY experience and MY preference and that's why they make chocolate and vanilla. everybody gets to choose for themselves. I have no passion in matter either way, I'm not keeping score of likes and don't likes. I do appreciate everyone's input and thoughts. It's kinda satisfying to me that I stumped the professor. (at least for now). :)
 

·
Registered
Joined
·
164 Posts
It's kinda satisfying to me that I stumped the professor. (at least for now). :)
Somehow, I don't feel stumped! I told you essentially what your lunch companion told you: That for street use, nitrogen is a bunch of hooey. I also said that the problems the race car driver was having with tire pressures when using air in his tires was probably due to the variable amounts of water which gets into the tires when being inflated with air, and the effects of high tire temperatures on the pressure which would be exerted by that water. I also said that I did not believe that the apparent observation that nitrogen does not leak out of tires as fast as regular air most likely is not due to differences in the sizes of molecules, and I gave a couple of examples where the larger molecules passed through the rubber faster than the smaller molecules So, what was I stumped on??? Bill
 

·
Registered
Joined
·
15 Posts
Discussion Starter #19
Somehow, I don't feel stumped! I told you essentially what your lunch companion told you: That for street use, nitrogen is a bunch of hooey. I also said that the problems the race car driver was having with tire pressures when using air in his tires was probably due to the variable amounts of water which gets into the tires when being inflated with air, and the effects of high tire temperatures on the pressure which would be exerted by that water. I also said that I did not believe that the apparent observation that nitrogen does not leak out of tires as fast as regular air most likely is not due to differences in the sizes of molecules, and I gave a couple of examples where the larger molecules passed through the rubber faster than the smaller molecules So, what was I stumped on??? Bill
I certainly didn't "stumped the professor" thing to be insulting or bad in anyway. I was really just being playful and making a joke based on your broad knowledge and yet having to dig a bit, etc. no harm meant ,please.
 

·
Registered
Joined
·
164 Posts
I certainly didn't "stumped the professor" thing to be insulting or bad in anyway. I was really just being playful and making a joke based on your broad knowledge and yet having to dig a bit, etc. no harm meant ,please.
No harm taken! As a scientist, I know that I don't know everything. What being a scientist has taught me is how to dig out the information and sift the good info from the bad. Bill
 
1 - 20 of 21 Posts
Top