9t6t7

Have G2 Goodyears on my Z and had the tires filled with nitrogen.
Tire pressure 32# when starting out and parked in the shade at a car show for about 6 hrs no problems. After 15 minutes of driving home the fronts psi were 40/42 rears were 38/38. Problem?????

EDinPA

Only if you paid for nitrogen.

Johnathon59

my pressure increases 2 lbs. from normal to being heated up when driven. your 8 lbs appear to be excessive, maybe defective sensors ?, check them with a tire gauge to be sure on your DIC readings.

TerryL

Suggest 26/28 psi when cold. Nitrogen doesn't bleed off like air which apparently means they gain psi when warm at a rate higher than air. Don't know why the difference between the fronts and rears though. Use a gauge you can trust and set them lower and then check again when warmed up.

Jeff-Ford

Using Nitrogen for everyday driving is a waste. Nascar uses it because they can predict much more precisely what tire pressure will be once the tires are heated up.

Joe1968ny

2 things about n2 one does not react the same as plain old air does to temperature and it has no moisture in it. Great for keeping wheels from corrosion or rust if they are steel.

EDinPA

When was nitrogen exempted from the ideal gas law? Must have been part of obamacare.

Pinky...

This. Complete waste of money.

50 4Ever

I had a similar problem with my CTS-V after I had a nitrogen fill. Funny thing was that it only did it the first time. I rechecked the pressure when cold and the dealer had put too much in the tires. I lowered them to 30 PSI and everything was fine. Unlike the rest of the guys I think nitrogen is well worth the money mainly because I don't have to fuss with the pressure. With plain old air on the other hand, I had to bring up the pressure every couple of weeks. Now I adjust the pressure 2 times a year.

that's my $0.02 worth

glennhl

Part right. Nitrogen reacts to temp the same as Air, they both act as ideal gases at the pressures we are talking about. However, the only reason to use Nitrogen is to guarantee that it's dry in order to avoid the partial pressure of water vapor versus temperature. But I agree with most here, using Nitrogen is a complete waste of money.

And if you want to know how Nitrogen or Air reacts to Temp, the pressure rise is directly proportional to the ratio of the absolute temperatures. At room temp, the absolute temp is 70 + 460 = 530 Rankine. Now let's heat it up to 100 degrees F, the new temp is 100 + 460 = 560 Rankine. If the room temp pressure is 30 psig, the absolute pressure is 30 + 14.7 = 44.7 psia. The new pressure will be (560/530) x 44.7 = 47.2 psia or 32.5 psig. So you can see the pressure rose by 2.5 psi when the bulk temp of the air inside the tire went from 70 to 100 degrees F.

2vettes

I once paid for lifetime nitrogen adjustments from my local Chevy dealership. The first time I need more nitrogen was first car event with car club in the Spring. The problem was, it was Sunday and the dealership was closed. Now I just have a compressor in my garage and maintain the tires at the appropriate psi. No more nitrogen

LS WON

If you purchase your tires from Costco that is what they put in your tires with the green cap.

cclive

And they don't charge extra for it...although you do have to replace that ugly green cap. I took mine off ahead of time.

cclive

No, it was exempted by the Corvette Forum. It's a concept (law of physics) that has just never caught on here. Gases do not follow it when they are inside Corvette tires apparently.

235265283...

Agree with glennhl Post #10.
And keeep in mind that air is 78% nitrogen anyway.

LS WON

ProfessorDeath

Don't bother.

Like dem Vettes

The ideal gas law is correct.

The benefits of nitrogen are (1) its lack of moisture, which can corrode sensors, and (2) the molecules of nitrogen are larger than air, which is about 75% nitrogen, thereby leading to less loss of air over time.

Expansion and contraction follow the ideal gas law.

Seadawg

I had the GEN2's originally on my Grand Sport, and I would only gain 2 to 3 psi with the GY's, and about the same with the Bridgestones on it now. I run normal air, not nitrogen.

Whether it is nitrogen or air, your pressure increase does seem a excessive for what you describe.

If the pressure increase is real, the tires/rims are getting much hotter, causing the gas to expand.

Is the wheel rim "hot"? If not, I would have the sensors checked, and also compare my tire pressure gauge to another one.

Then, if the wheel rims are pretty hot, I would check to find out why. Brakes dragging (possibly, since all 4 wheels are reading high), unusually sunny/hot black asphalt road surface, spirited driving, etc.

FortMorganAl

You're in for it now. IRS audits every year. Every thought you have recorded and saved for future prosecution. Someone watching every key you type as you type them. Just pray you don't get Benghazied. OH CRAP!!! I used the "P" word. Now I'm on the enemies list also! (As if I wasn't already )

Now to answer the OP's question - yes, you have a problem. 8 pounds is way too much change. The sensors don't communicate continously when not rotating so you can have some difference between actual pressure and DIC reading but after 6 hours the pressure should be correct and it should be correct when driving. First step to resolving the issue is to duplicate and verify it with an independent gauge reading. Also press the valve and let a small amount of air out and see if it you get fog or water droplets. If you paid for the snake-oil nitrogen, you might want to go back and tell them they have a problem. Give them the option of making your tires not change pressure with temperature as the nitrogen scammers claim or giving you your money back. I'm sure they will opt for the latter because the former is physically impossible.