Lexmex

Down here in Mexico...the Costcos never even heard of nitrogen.

I go to a tuning shop where it comes out to about $5 USD equivalent per tire. I have been using it for almost a year.

I have a friend with a Mazda RX7 and is impression of using the Nitrogen down here is less resistance to temperature changes in the air an track...feels even wether in drag racing or even better in autocross.

tcheung87

Alright thanks for the knowledge fellas, I guess I'll go to Costco and ask about it... Good thread by the way.

gsenthil

Nitrogen also has the advantage of not expanding under heat and so your hot/cold tire pressures remain at the same psi. Being a larger molecule it also doesnt leak like air so you have to check your pressure less often.

Pretty much all US-Costcos have nitrogen free for those who buy tires from them. It used to be free for all members but they changed it

My friend had the Geolander and it makes a howling noise on freeway speeds. He doesnt realize it but when we switch cars he can tell mine is quiter.

HarrierAWD

I'd recommend the original OEM tire - Bridgestone Dueler H/T D687. I got these tires from CostCo after 53K with the Goodyear Integrity. The Dueler brings out the Lexus out of my Lexus. I should've asked my dealer to put these on when I got my RX300. $95 each installed at CostCo. This tire does just about everything well - braking, handling, ride, noise, you name it.

We just had a serious snow storm in Colorado, followed by strong gust and below 0 F temperature. I am impressed with its ability in snow and ice even in extreme cold. (Don't ignore snow capability, you never know that you might take a trip to Reno/Tahoe.) And it took me virtually no effort to keep going straight in 50-75 mph sideway gust - unthinkable in an SUV.

Not sure about its wear... the wear index is 300, so it may wear faster than the Goodyear (440.) It does have 60K mile prorated warranty. Rolling resistance is higher than Goodyear as my gas mileage drops by estimated 1 mpg.

larrytrk

Do not get Firestone Destination LE tires, they are very noisy and give a harsh ride!!

Lil4X

Costco seems to be promoting this idea that their "air" does not expand with heat. That may be a surprise to Messrs. Jacques Charles and Joseph-Louis Gay-Lussac, whose 19th-Century equations for the expansion of gases with heat postulate a direct relationship between temperature and volume. Actually, the great advantage of nitrogen is that it is DRY. Eliminating water vapor (present in compressed air) will considerably reduce the effects of tire temperature on pressure - which is a great idea. Also, eliminating oxygen from the air in your tires could very slightly increase tire life by replacing the reactive element with an inert one.

If I can throw my mind back to all those chemistry classes I slept through in school, I seem to recall the ordinary air we breathe is something like 78% nitrogen. Oxygen comprises about 20% of our air and is a slightly larger molecule (O2) than nitrogen (N2). Eliminating trace amounts of very small molecules, hydrogen (H) and helium (He) in the inflation medium would probably have a minimal effect on tire pressure.

See? At last a use for all of those Chem classes! My education can no longer be considered a total loss. . . . well, that and the ability to consume vast quantities of beer . . .

jfarber

I'm not sure what advantages Nitrogren offers, but I do know a couple things.
-Nitrogen is not inert, it reacts with other elements to form compounds. Nitrous Oxide is an example.
-Nitrogen is an element, not a molecule. Number 7 on the periodic chart.

I'm not trying to be a smart-***, I just thought this might help.

mikey00

I wonder if the slight drop in mileage is really due to a higher rolling resistance, or just the fact that you went from a worn tire to a new one, which increased the diameter. Now your car is actually covering a little more distance than before. But the computer doesn't know it.. Assuming you used about 9/32 of tread depth on your Integritys, you added 18/32 to the diameter when you repaced them. This comes out to be 1.77" additional circumference. That comes out to about 6% or roughly 1 mpg.
I would also be concerned about the wear rating as you mentioned it is only 300. Cross Terrains are 700 and most others are in that area. That means Cross Terrains would have to be more than double the cost of the H/T D687 for the cost per mile to be equal. I also noticed that the traction is only "B" while the CT has an "A". I agree that the UTQG treadwear ratings are not perfect but they are the best indicator available to us.
Also if you look at Tire Rack consumer ratings, the Cross Terrains come out far ahead in every performance category tested. The consumer wear rating is almost double for the CTs. This is based on over 1,000 surveys and over 25 million miles driven on these tires. Again not perfect data but I am starting to see a trend here.
The Cross Terrains did not do very in recent Consumer Reports testing but they only tested the 235 size, which most of us know by now is a special cheaper OEM Cross Terrain which does not have the same Cross Terrain specs.
Damn, I am starting to sound like a Michelin salesman, but I am about to buy my second set.

salimshah

Mikey00:

It depends upon how the mpg is calculated [by onboard display or driving a known distance]. The known distance will see the phenomenon you described, but the displayed mpg will not.

The onboard computer, mpg AND the odometer both really calculated based on the rotation of wheel. So the distance read by the computer, would read less miles between two points with increase in tire circumfrence. Assuming every thing is identical (except dia) the mpg display would be less than before.

Inertia [better roll, can require more gas to get gowing], lower drag will get you better "displayed mpg".

Salim

HarrierAWD

Possible about the mileage. My Goodyear Integrity still had 4/32" to 5/32" left after 53K miles. I changed them because of Colorado winter. I do notice, however, when I lift off the gas pedal (when approaching red light,) my RX does not roll as far as it used to.

Frankly, the wear, traction, and temperature index on the sidewall are as good as used toilet paper. CR tested a tire with a whopping 800 wear index, yet it received only a fair rating in tire wear. Since the Dueler has a 60K pro-rated warranty, I don't worry about it.

If you look thru TireRack's rating, just about everybody knocks OEM tires. Then the more expensive the price or the more exotic the tire name, the better the rating. It's all psychological. If the 235 Michelin CT sucks, I don't think the 225 would be any good, either.

And I wonder why you still haven't bought your 2nd set of CT.... you've been talking about it for a long time. Winter is here and it's snowing in NJ. If you like CT, buy them already.

HarrierAWD

The CostCo pure Nitrogen provides no advantage over plain air. It's just a marketing gimmick. Just like bottle water isn't better than municipal water supply. Tires are always exposed to air, which contains N2, O2, water vapor, O3, and whatever pollutants out there.

There's virtually no hydrogen or helium in the air we breathe. They are very light so they'd go high up in atmosphere. Helium only exists naturally underground and cannot be produced. The U.S. government controls all the Helium supply in the country and store it underground somewhere in Kansas.

mikey00

Yes it is winter and snowing in NJ but after 60K my Cross Terrains stil have about 5/32 left on them and performing ok in the snow. I am waiting for the next $60 off sale at Costco which is coming in January.
I hear what you are saying about the more people spend for a tire the higher they tend to rate it. But the opposite is also true, the more you spend the more you expect. Even if we ignore all personal opinions, Michelin itself has lower specs for the 235. How do you explain this?

mikey00

Salim,
I may be missing something here, but how does the displayed mpg not show the difference when it is based on rotation of the wheel and the wheel is actually going more distance than the computer thinks it is?
I would think that computing by driving a known distance would not show the phenomen I described because you are using true miles driven and fuel consumed. Using the computer would show the phenomen I described because it is based on wheel rotation and the computer thinks the car is traveling less than it actually is. Also lower drag should get you better MPG computed by actual distance as well, not just "displayed mpg".

Mike

salimshah

If you folllow my logic [could be flawed], the larger diameter (circumfrence) wheel will register less rotations on the onboard computer. Exagerated example to show what I am saying... Say you install twice the radius tire => 2*Circumfrence. 1 staute mile [if it showed 1 mile on the on-board-computer with smaller tire] will be registered as 1/2 a mile with larger tire (less rotations to cover the mile). Now take a small leap with me and for current argument sake assume same volume of gas is used then MPG will be 1/2 of what it had with smaller tire.
Net=> Newer tire will display less milage and less mpg on the display. Reality: Is what you stated in your first note. I am simply saying that the displayed information will show you the wrong value. [limitation is, due to the fact it is counting revolution of the shaft]

Salim

mikey00

Got it. We are both saying the same thing, just in a different way.