Tires from Costco

[mrondeau]

Has anyone ever gotten tires from Costco and if so, how was their service? They have tires at a great price (about $150.00 less for a set), but I don't really want to get them from Costco if they don't do a good job.

Thanks,

[Michael Dolphin]

Has anyone ever gotten tires from Costco and if so, how was their service? They have tires at a great price (about $150.00 less for a set), but I don't really want to get them from Costco if they don't do a good job.

Mark, I wasn't sure as I read whether you were asking more about Costco service or Costco as a source of tires. The first consideration, of course, is specifically to the tires that you are buying. After that, you want to protect your wheels and get tires mounted and balanced well.

Since you have a new car, and with a warranty, you may already know that you should only consider those tires on Porsche's approved tire list. There are a hundred good reasons to do so. See an article I wrote title "Tires - the Ride of Your Life" at www.pca-chicago.org/scene/SceneFeb05.pdf

The points in the article will apply even if your question was actually in regard to your other car.

Tires are the final determinant in whether your car stops -- or slides....

Hope the article answers your questions.

[Michael Dolphin]

Additional point -- check Tire Rack or other web site for best price. If you provide that reference to Discount Tire or America's Tire their unwritten policy is to match those prices...

[Tawfik]

I have done this a few times:
Get a quote from Costco then head to Discount tire and they always beat the costco prices by a few bucks.
I also believe that Costco uses Nitrogen to fill tires they install.

[LUCKY DAVE]

I can't believe I'm hearing that old wives tale about "fill your tires with nitrogen" on this forum. You guys should know better.

[mrondeau]

The tires from Costco are Michelin PS2 N1's. The same as I have now. I was just curious about service. I will get a quote from them and go to Discount tire. I've used them before and they've done a good job for me on all of my cars. Thanks for the info.

[Ted Myrus]

What nitrogen wives tale? I'd like to hear the science associated with that. N 7 14.0067

[LUCKY DAVE]

What nitrogen wives tale? I'd like to hear the science associated with that.

Nitrogen. What do you think air is made out of?
This old myth has been around longer than the one about not putting batteries on a concrete floor, or too hot of a spark plug causing detonation.
It's origin is in the military fighter aircraft industry, where very high inflation pressures are the norm.
At high inflation pressures, oxydation of the tire/rim assembly happens faster (Especially when real mag wheels are used) and military airplanes tend to sit around a lot. The tires may not get changed for many many years.
Most aircraft have oleo suspension struts that must be pressurized with nitrogen to avoid the explosion danger of compressed air (oxygen) and oil together.
Since air compressors cost money and take up space, and the hangar has to have a nitrogen bottle anyway to service oleos, why not just fill tires with nitrogen and save some hassle/money?
Pretty soon Bob the hotrodder is hanging around, and sees the mechanics fill the Chuck Yeager's tires with nitrogen, and he thinks "Wow, I'll fill the tires in my Biscayne with nitrogen, and beat Larry on Saturday night" and the myth is born.
At any forseeable service temps, filling race car tires with nitrogen is silly, the difference is too small to measure.
BTW, I spent a few seasons working with Dunlop as a racing tire technician (tire fitter) on the motorcycle 250cc and 500cc GP circuit, and we filled the World's Champions tires with.........air. There's nothing any of us know about tires that Dunlop's GP engineering team doesn't. When we asked them about filling the race tires with nitrogen, they laughed at us.

[Jad]

I still believe the N2 theory is true. If you compare N2 to O2, you are probably correct, but 'air' from a pump has a lot of water in it and the water is what reacts to the heat and causes the issues in the tires, not the O2. And storing N2 is safer that pure O2, so I think that is where the use of N2 comes from. Also, the only issue is how much heat increases the pressure. A prof team know exactly how much the tires will heat up, so they just adjust the values. We do not, so a more consistant pressure allows us to stay closer to a target value.

That all said, I am too cheap and lazy and use air.

[ttweed]

At any forseeable service temps, filling race car tires with nitrogen is silly, the difference is too small to measure.

Like many "wives tales" (which I feel is a colloquialism that is a bit demeaning to the intelligence of women), I believe there is a kernal of scientific truth behind it. If you use dry air to fill the tires, I would agree--the differences would be negligible. The problem is, as Jad mentioned, the amount of water that most common compressed air sources put into the tire along with the air. Pure, bottled nitrogen is a very dry gas. The humidity in air as it is compressed results in liquid water condensing in the compressor storage vessel, and unless a well-maintained, industrial-strength drying unit is used, some of this is transferred to your tires when you fill them with compressed air.

From what I understand, it is the phase change of this liquid water which causes greater pressure increases in the tire compared to a dry gas like nitrogen when a wheel is heated to racing temps. I do know that the volume of liquid water expands by a factor of 1700 when vaporized into steam, as this is the principle by which steam engines operate. Having never measured temps inside a hot tire, I can't say for sure how hot the air gets, but if the outside carcass is 220F, wouldn't it be very possible that some of the water inside has heated to beyond its 212F boiling point?

Like Jad, I have never bothered to utilize nitrogen in my tires due to the logistical problems involved, but many modern race teams do, in order to make pressure gains more predictable. To eliminate water from the tire would require purging it at least twice when filling with nitrogen, and would require that a non-water-based tire bead lubricant be used when mounting the tire, or the leftover water from the lubricant trapped inside the tire would defeat your nitrogen fill anyway. When I watch my tire guys swab the bead with a big brush of water-based lubricant, I realize that it is probably a lost cause for me to use nitrogen.

Outside of the auto racing sphere, the benefits of nitrogen filling regarding long-term maintenance of tires and wheels was indeed first recognized in aviation, where tires must operate in more extreme temperature and pressure conditions than automobiles, and where performance is more critical, but it has spread to trucking fleet maintenance and now is as common as your local Costco. The inhibition of oxidation of the tire and wheel material is one factor, but the migration of nitrogen through the rubber membrane of the tire is another. I believe there is evidence that nitrogen migrates out of the tire at a rate 3 to 4 times less than oxygen, due to the larger molecular size, but since air is only 21% O2, the actual pressure loss is probably less than twice as much over time. Nevertheless, it seems that fleet owners have recognized enough savings in tire maintenace and fuel costs over the long run to justify using nitrogen fills.

I am not a tire engineer, but I did stay at a Holiday Inn Express once.

YMMV,
TT

[LUCKY DAVE]

Yes, dry air (or nitrogen) would be nice, and yes, the drippy globs of liquid tire lube left inside a mounted tire makes the tiny amount of water in solution in the air from the hose laughable.
Remember, yes the air coming out of the hose has a little water in it, but it's already a gas - it can't "boil" and increase it's volume 1700 fold.
If you really wanted to use a "way cool" gas for inflation, you'd use helium, for it's extremely high coefficient of thermal conductivity.
Of course, helium molecules are so small the gas leaks through rubber tires like air through a screen door. Bummer.
The first time we setup to work tires with Dunlop at a world championship event, (we had been the north american Dunlop guys for the AMA superbike championship up to that point) we busted out our nitrogen bottle setup proudly, (Yeah we know something - see our trick stuff? )and the european Dunlop guys laughed their heads off - "No wonder you ignorant Yanks never win anything, you don't know anything!"
We hung our heads and put the bottle away.

[LUCKY DAVE]

I just re read my previous post, and realized I left something out. The "European" guy (I think he's actually an Amercan who works the Moto GP's) that was laughing at us was (is) Dunlop's chief racing tire engineer, Jim Allen, based in England. I think he knows a thing or two we don't........

[Zulu993]

A bit late, but Happy Mother's Day to the PCA women that stand behind us and allow the little boy in all of us to go beat up cones when we really have a long list of Honey Do's.

Honey, honestly, nitrogen won't cost anymore than air! I promise.... and the tires will last longer.

[LUCKY DAVE]

If we're worried about tires dying from old age on sports cars...........we don't understand the concept.