08C6Z51

Just got an 08 C6 Z51 triple black. Due to weather it has been garaged all winter without much use. with only 400 miles on odometer. Is it normal for the tire pressure to drop while the car is only sitting in the garage? It drops down to 22 to 27 PSI in all four tires.

When we bought the 'Vette they filled the tires with nitrogen, stating it would prevent air leaks. It hasn't worked (didn't really believe it would anyway).

Thanks for any input. Don

kenjeffries

Well technically, if the tires are filled with nitrogen, they won't leak air. There is no air to leak. But they will leak nitrogen.

TiVoManiac

Depending on how warm it was when you put it in there and how warm it is in there now it is possible.

Red86Cfour

Nitrogen will leak out easier than air (molecules are smaller I think, but its relative anyway). The only advantage nitrogen serves is that because it is dry (no moisture) it won't expand as much as air out of a compressor that hasn't had the water drained in a while. The pressures stay almost the same whether the tires are hot or cold. Thats why pro race teams use it.

Datawiz

Make sure the nuts on the valve stems are tight.

johnodrake

Normal for pressure to drop as it gets colder.

Nitrogen has no capacity to seal leaks. It is a gas.

su8pack1

Cold weather will always do that. Mine are down to about that now after sitting for the past 5 months. They'll come close to normal as either you or the weather warms them up.

obxchartercaptain

08Roadster

Had the same issue with mine....put my vert away in November and this past week the tire pressure was down also. The tires on the Z51s are very sensitive according to GM.....fill them up to proper pressure and just keep an eye on them. Should be OK once we start using the cars on a regular basis with the nice weather.

talon90

Tires filled with air will drop on average 1 pound for every 10 degree drop in temperature. This is why they recommend 30 psi cold as the fill so that as the tire heats up it will get them up to about 34 psi while on the highway. It isn't likely a leak as much as it is density changes.

Tire pressure is not a set it and forget it item. It will need to maintained as the seasons and temperature change.

Darwin11

That is a serious problem and i think they need to be replaced and sent to me.
You pay shipping also...

BigButtLover

Modshack

Check your TPMS stem torque values...I had a light leakdown in my right rear...Bought a cheap ($20) 1/4" Harbor Freight torque wrench and retorqued all of them to 60 inch pounds. Every one of them was under spec by a goodl amount. Seems to be holding just fine now..

mikesul

Nitrogen molecules are larger than oxygen, thats one of the reasons it's not supposed to leak.

Red86Cfour

You might want to consult the periodic table. In any case, nitrogen isn't going to "prevent" a leak any more than using air out of a compressor will.

08C6Z51

Thanks for the replies. I am learning as I go with this new car. We've had a C3 (74) Vette for years and I work on the old one myself but I wouldn't touch the new one (yet).

shopdog

The N2 molecule does have a larger diameter than the O2 molecule. The reason is that oxygen is more electronegative than nitrogen, so the molecular bonds are stronger and pull the atoms closer together. It isn't all that much closer, though, and ordinary air includes other gases, such as CO2 and H2O, which are much larger than either N2 or O2. So molecular diameters don't really count for much in the comparison between pure N2 and 78% N2 (ordinary air).

The key thing to remember is PV = nRT. It isn't just a good idea, it is the law, the ideal gas law, and pure nitrogen has to obey it just the same as ordinary air does. What it means is that pressure rises and falls in proportion to changes in temperature. For auto tires filled with either pure or 78% nitrogen, that means a 1 PSI pressure change for every 10 degree change in temperature.

Petew1971

Victoryred 08

When I store my cars in the first of November, I inflate tires to 40lbs air pressure. Come April, I check and pressure is down to 30lbs. Cold weather will decrease pressure as talon90 stated, 1lb for every 10 degrees drop in the temp.

cclive

This is akin to the way helium leaks out of a balloon faster than air does...smaller molecules...