texas911

Why the hate for Costco, its freaking free! Why the conspiracy theory? Its not like they require you to fill your tires with Nitrogen everytime you go there.

Marv

Actually, you want too use hydrogen to reduce unsprung weight.

Marv

The moisture is due to the Bernoulli effect of compressing and uncompressing a gas. When a gas is warmer its capacity to hold moisture is greater. When you release pressure the gas cools and moisture condenses from within the gas and the air around it. The moisture inside the tank is partly due to the warmed air upon compressing will absorb moisture. As the air in the tank cools to room temperature, moisture condenses inside the tank.

I don't know that nitrogen will retain less water under the same conditions. I doubt there is a difference. However, nitrogen is inert and will not oxidize. There is probably more benefit from that property than anything else. Oxygen is very reactive, but if you want something really reactive, try fluorine!

Marv

pcar964

I wonder how a hydrogen-filled tire would work with a flame-shooting exhaust

gonzilla

When I had an alignment done at Lucent they filled with Nitrogen. Tom told me not to touch the tire pressure until I came back. Well, that was about 2 or 3 months ago and my tire pressure hasn't changed at all. Don't know if the nitrogen has anything to do with that or just the nice new tires, but I was surprised to see that the pressure hasn't changed at all.

TomF

Marv, you beat me to it!

Adrienne

Only dogs could hear them when they squealed.

KOAN

Discount Tire and Belle Tire here also use nitrogen. They have nitrogrn extractors, so it is always available to them. Because most of their business involves the use of compressed air driven tools (I was told by the supervisor), the dry air makes their tools last much longer, and is cost effective. Filling the tires will certainly stabilize the pressures over temp. changes, but I think this is an unintended benefit. At the track, I routinely see an 8-10 lb. increase in pressures, and am contemplating using nitrogen to reduce it. The stuff is pretty cheap (approx. $15-$20 a season with 12 events and 2-3 sets of tires). The disadvantage is getting a tank safely to the track. If you fill and purge a tire a few times, you'll get enough nitrogen % to make a significant difference.

JasonAndreas

The machines in use at Costco, Discount Tire, etc. can only produce gas that is 95% nitrogen. There was another discussion about this over on the 997 forum.

The GrandAm DP cars that run 100% nitrogen see the same 10lb increase, there was a little SpeedTV piece about it a few races ago.

Flying Finn

FYI,

You can put the "dryer" (cheap thing that painter's use) to your air compressor hose if you want to get rid of humidity.

tj90

I was at COSTCO and saw the sign touting its advantages. I actually considered getting tires there once, but I found their pricies were not that great compared to other retailers. But the N2 sign sealed the deal for me. I will never get tires from there....

But I do find myself craving joint juice and fish oil tablets after seeing their adverts on the gas pumps outside. Snake oil? Nah, they just hope you walk out with some more crap that just came off the cargo ship that you dont really need....

Bob Rouleau

It isn't snake oil. Dry gas expands less than gas containing water. Water makes things rust - no water means no rust. Some tires have steelo belts. N2 is less corrosive than air even if the air has been filtered dry.

Nitrogen is better which is why race cars and airplanes use it. Performance tire dealers always fill race tires with N2. I don't know if Costco purges tires or not, if they do, great. If not, well it's free so why quibble?

Best,

993_Pilot

[QUOTE=Bob Rouleau]...Nitrogen is better which is why race cars and airplanes use it. Performance tire dealers always fill race tires with N2. I don't know if Costco purges tires or not, if they do, great. If not, well it's free so why quibble?QUOTE]

A-men ! Airplanes and Race cars go through much greater temperature cycles and so nitrogen helps. It is probably overkill on a street vehicle, but if it is free, then why complain?

JasonAndreas

FAA regulations require it to reduce fires hazards during landings caused by overheated rims.

“PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES 25.733 (e) For an airplane with a maximum certificated takeoff weight of more than 75,000 pounds, tires mounted on braked wheels must be inflated with dry nitrogen or other gases shown to be inert so that the gas mixture in the tire does not contain oxygen in excess of 5 percent by volume, unless it can be shown that the tire liner material will not produce a volatile gas when heated or that means are provided to prevent tire temperatures from reaching unsafe levels.”

Water vapor is still a gas and won't deviate that much from pv = nRT at the tire pressures we use. Even if the error was 5% (the maximum error rate listed in Marks' Standard Handbook for Mechanical Engineers) and the tire contained 1% water vapor you'd still be below the accuracy level of most tire gauges. Maybe in F1 where 1/8 PSI matters. But in this case Costco is not selling dry gas they are selling 95% nitrogen which as the Finn points out can be just as wet as air coming out of regular air compressor with an inline dryer.

Because it's a sales gimmick that is not free everywhere and the advertised reasons for using it don't past the smell test.
Its a convenient source of dry gas, that I can understand but any other reason...

"Pressure will increase or decrease to the same extent as the temperature increases or decreases regardless of which gas is in the tire."

sww914

I'm more worried about blowing up my hotrod 4 cyl. than I am about the relative humidity of the air inside of my tires.
Who ever heard of tires rotting from the inside? Steel belts rusting out? I've been driving for 25 years, and I've never had a tire explode from rusty steel belts. every tire I've ever seen the inside of looked pretty darn nice compared to the outside of the sidewalls.
I think that in airplanes that are subjected to super low temperatures and very low ambient pressures it is completely valid to use a very dry gas that has less of a tendency to expand, but my car has never been at 40,000 feet, and it never gets to 30 below zero on the California coast.
Most of the tire shops in my area are offering nitrogen fills, so you're not married to Costco around here, anyway.