For $25 repair shop is offering to replace tire air and fill tires with 100% nitrogen. Anyone have any opinion on this practice?

 

For a passenger car it's generally a waste of money. It helps prevent oxidation of the tires which makes them harder. The reason I say it's a waste is we generally replace our tires before they have a chance to oxidize. So unless you plan to store your car for many years then it's not worth it.

Using nitrogen is pretty common for big rigs because they re-cap the carcasse many times. So the longer they can make then carcasse last the more money they save.

It's also used in racing. Mainly because 100% nitrogen has no moisture content like normal air. So when the tires get hot the pressure builds less. This makes the tires more consistent for racing.

That's my opinion.

 

I just did that a couple of weeks ago (same price as you are being quoted). I wanted to get rid of the pressure fluctuation now that our temps in GA are colder. I am surprised that my tire pressures still change by 2-3 lbs as they warm up. I plan to stop back to the shop and get their opinion

Not sure how they can get all the air out of run flats before putting in nitrogen. My shop deflated & refilled with nitrogen three times to insure highest concentration.



Don

 

The ideal gas law, PV=nRT, says that you should expect a change in pressure for any reasonably ideal gas.... meaning you'll still get pressure fluctuation out of nitrogen....

 

I had N2 in the tires when they were fitted in Vegas. I saw no value and the pressure fluctuations were just the same. It came free but I surely wouldn't pay $25 for it.

 

Come over to my house and I will fill them with 80% Nitrogen for $20.

Please God, somebody stop me.

 

I personally wouldn't spend $25 on it. But, it's your money.

 

Normal air is already 78% nitrogen, 21% oxygen, and about 1% argon and a few other trace gases. It does however, normally have water molecules (moisture) as seen by the Relative Humidity reported by your local weather man every day. Relatie Humidity is a measure of the amount of moisture the air at a specific temperature is capable of holding. As the air warms up, it's capability to hold more moisture goes up (as long as you don't add more moisture to a given volume, as it heats up, the Relative Humidity goes down, the Absolute Humidity stays the same). Typical values of moisture are likely to be only about 100 grains (a grain is 1/7000th of a pound) of moisture per pound of dry air. Usually, nitrogen that comes in bottles has no moisture content. So the only advantage I see to filling tires with nitrogen is to eliminate the moisture (nitrogen blankets are a common practice in preventing moisture inside large industrial chemical tanks). I've never heard of oxidation of rubber, but you definitely can have oxidation on the surfaces of the metal wheel which are inside the tire, and in our C5s, the tire pressure monitors may be affected over long durations. If you're that concerned about moisture, I think I'd pick a nice dry day (after a weather front has moved through) and deflate/fill my tires then - the compressor just takes the outside air (dry), compresses it, and shoves it in the tire. I don't think I'd pay $25 for a N2 fill. Just my .02.

 

Since you asked, I have an opinion on it. It's a ripoff, and of no value to you. Someone will argue that the pressure won't change with temperature and even give examples. But it will. And when you need more air, are you going back and buy more nitrogen? And how do you know what the actual percentage of nitrogen they're putting in? I use 78% nitrogen, 21% oxygen, small amount of Co2 and other gases. I have a device that removes it from the atmosphere and compresses it and forces it into the tires up to 30 psi cold. Only since you asked would I offer my opinion, and if you do it, I won't criticize. It's your money.

 

Save your money

 

The local Costco puts nitrogen in your tires when you bring them your car for any tire service. There is no extra charge for the nitrogen. Although I have not brought them the vette, I did bring them my 01 Civic. I have noticed a 2-3 mpg increase in gas mileage, since they filled the tires with nitrogen. I also observed the tires do not seem to lose pressure as did they did when they filled them with air. Perhaps the two are related

Mordi

 

well no need to mention the 78% nitrogen, 21% oxygen in the atmosphere as others already have, but when i had the tires put on my jeep at a tire shop in Syracuse NY it was included free with the purchase of new tires, they were only charging $2 per tire for other customers to fill there car.

 

As Johnny Carson used to say "you are correct sir"

 

My opinion is that it is a waste of your $25. There are much better things that you could spend your money on for the car. The reality is that you will still see some fluctuation in pressure. Nitrogen fill is great for the person that will be storing the car for a prolonged period of time since in an ideal fill situation the Nitrogen will be dryer and subject the tire to less damage from moisture. Short of that for everyday use there will be negligible benefit from the change.

 

I've added nitrogen to my tires and gained 12 - 15 RWHP.

 

 

 

Thomas Tusser said: "A fool and his money are soon parted."

Save your $$$$$'s for something that makes sense!

 

unless you are flying your car you don't need it. Planes have it because they go from -30 to 110 and more at touchdown.

 

Chuck