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GM shipping Vehicles with nitrogen filled tires?


Pwning Robert Hollar

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Nitrogen ... what a joke. Since air is something like 80% nitrogen to begin with, adding it to tires isn't going to amount to much. Biggest scam ever devised, IMO.

 

Maybe the only benefit is that it's 100% dry ... but since tires leak a few percent per month, or week, that benefit isn't going to last very long. The fact that it doesn't change volume with temperature isn't going to benefit any street driver either.

 

Actually the main reason they use 100% nitrogen in NASCAR is simply due to being 100% accurate in predicting pressure in relation to temperature changes in the tire. When using straight air, there is some percentage of moisture in it, and that can change from 0 to 99% depending on the air on the suction side of the compressor. Moisture will impact pressure at a different rate depending on humidity.

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Thanks Ryan, I am hoping to get an answer from someone with some years experience with GM, because this was supposedly something that happened in the past under the "old GM".

Your welcome, not sure what you mean by years of experience but I know a few people who work at various gm factories. I confirmed with two of them at truck plants.

 

 

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The fact that it doesn't change volume with temperature isn't going to benefit any street driver either.

 

 

 

 

Every gas expends when heated and contracts when cold. Nitrogen just does it is a predictable way.

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It just expands at MUCH less of a factor than any other gas, particularly o2, CO2, and whatever else is in the air besides nitrogen. An increase in tire temperature from 40° to 100° @ 35 psi will only increase in pressure 5.97 psi. It's great for shock absorbers, where there is zero permeation. It will stay 100% nitrogen @ 0% humidity throughout it's lifespan. Shocks on race dirt bikes get pretty hot - no other gas would work in keeping the rear suspension predictable from the start, to the end of the race.

 

It's also great for testing A/C systems for leaks, since there's no moisture in it.

 

NASCAR, where millions of dollars are on the line, yeah, I can see taking advantage of anything you can to get ahead. Using it for tires in a street driven car, and PAYING for it, is laughable, IMO.

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Nitrogen ... what a joke. Since air is something like 80% nitrogen to begin with, adding it to tires isn't going to amount to much. Biggest scam ever devised, IMO.

 

Maybe the only benefit is that it's 100% dry ... but since tires leak a few percent per month, or week, that benefit isn't going to last very long. The fact that it doesn't change volume with temperature isn't going to benefit any street driver either.

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The people that use the theory that nitrogen has a larger molecule than oxygen so it will leak less "through" rubber forget that unless you run 100% oxygen in one and 100% nitrogen in the other, homogeneous mixtures like air cannot just "release" the oxygen so it can leak out through the tire. Even if you could just leak oxygen, only 20% of the entire contents is oxygen initially, and if it leaks out that percentage will drop, eventually leaving the tire with about 20% less pressure(35 psi now at 29 psi), but, good news, no more leak.

 

In addition to checking pressures when cold, it is actually more important to always check pressures in the same environment the vehicle operates. I used to live in a town north of Toronto. During winter months when I was in my early 20's, typical daily high temp one January was about -30 degrees F for most of the month. I did a winter tire change over on a customer car that had been in the shop for the past 3 days. I changed the tires over, parked the car outside. Next morning the customer got onto the main road and had one rear tire go instantly flat, no warning, just flat. Right rear tire had less than 15 psi in it. Front tires were also quite low, but, near as I can figure, it was the spinning of the near flat tire that popped the bead I have not run into that since then. Where I live now we do not have the huge swings in temps like back then. Over a hundred in the summer, below -35 in the winter then.

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We get pretty wide temp swings here. Saw -14°F last February one morning, and 96° with a heat index of 113°F in summer.

 

Since I got that waste oil burner built and running, I always keep in mind the temperature change. I'll add an extra 8 psi sometimes when it's 60° in the barn and in the single digits outside, then check them again after it sits out there a while. If the customer is in a hurry, I let them know to check the pressures the following morning. Amazing how much the pressure will change.

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Thanks Ryan, I am hoping to get an answer from someone with some years experience with GM, because this was supposedly something that happened in the past under the "old GM".

 

Never happened with "old GM" and doesn't happen with new GM. GM does not fill with nitrogen. Dealer thing or tire shops do it.

 

GM's position on nitrogen in tires:

 

GM's Position on the Use of Nitrogen Gas in Tires

 

General Motors does not oppose the use of purified nitrogen as an inflation gas for tires. We expect the theoretical benefits to be reduced in practical use due to the lack of an existing infrastructure to continuously facilitate inflating tires with nearly pure nitrogen. Even occasional inflation with compressed atmospheric air will negate many of the theoretical benefits. Given those theoretical benefits, practical limitations, and the robust design of GM original equipment TPC tires, the realized benefits to our customer of inflating their tires with purified nitrogen are expected to be minimal.

 

GM’s Position on the Use of Green Valve Stem Caps

 

Green valve stem caps should not be installed on vehicles in dealer stock, and should only be installed at point-of-sale if the owner of the vehicle approves/requests that they be installed along with nitrogen.

 

Important: The use of non GM valve stem caps can result in a loss of sealing at the cap. This may allow contaminants/water into the valve stem. These contaminants can damage/destroy the TPMS and such damage caused by leakage of contaminants would not be covered by the GM New Vehicle Warranty.

 

The Promise of Nitrogen: Under Controlled Conditions

 

Recently, nitrogen gas (for use in inflating tires) has become available to the general consumer through some retailers. The use of nitrogen gas to inflate tires is a technology used in automobile racing. The following benefits under controlled conditions are attributed to nitrogen gas and its unique properties:

  • A reduction in the expected loss of Tire Pressure over time.
  • A reduction in the variance of Tire Pressures with temperature changes due to reduction of water vapor concentration.
  • A reduction of long term rubber degradation due to a decrease in oxygen concentrations.

    Important: These are obtainable performance improvements when relatively pure nitrogen gas is used to inflate tires under controlled conditions.

The Promise of Nitrogen: Real World Use

 

Nitrogen inflation can provide some benefit by reducing gas migration (pressure loss) at the molecular level through the tire structure. NHTSA (National Highway Traffic Safety Administration) has stated that the inflation pressure loss of tires can be up to 5% a month. Nitrogen molecules are larger than oxygen molecules and, therefore, are less prone to “seeping” through the tire casing. The actual obtainable benefits of nitrogen vary, based on the physical construction and the materials used in the manufacturing of the tire being inflated.

 

Another potential benefit of nitrogen is the reduced oxidation of tire components. Research has demonstrated that oxygen consumed in the oxidation process of the tire primarily comes from the inflation media. Therefore, it is reasonable to assume that oxidation of tire components can be reduced if the tire is inflated with pure nitrogen. However, only very small amounts of oxygen are required to begin the normal oxidation process. Even slight contamination of the tire inflation gas with compressed atmospheric air during normal inflation pressure maintenance, may negate the benefits of using nitrogen.

 

GM Tire Quality, Technology and Focus of Importance

 

Since 1972, General Motors has designed tires under the TPC (Tire Performance Criteria) specification system, which includes specific requirements that ensure robust tire performance under normal usage. General Motors works with tire suppliers to design and manufacture original equipment tires for GM vehicles. The GM TPC addresses required performance with respect to both inflation pressure retention, and endurance properties for original equipment tires. The inflation pressure retention requirements address availability of oxygen and oxidation concerns, while endurance requirements ensure the mechanical structure of the tire has sufficient strength. This combination has provided our customers with tires that maintain their structural integrity throughout their useful treadlife under normal operating conditions.

 

Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure maintenance of tires is critical for overall tire, and ultimately, vehicle performance. Maintaining the correct inflation pressure allows the tire to perform as intended by the vehicle manufacturer in many areas, including comfort, fuel economy, stopping distance, cornering, traction, treadwear, and noise. Since the load carrying capability of a tire is related to inflation pressure, proper inflation pressure maintenance is necessary for the tire to support the load imposed by the vehicle without excessive structural degradation.

 

Important: Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure maintenance of tires is critical for overall tire, and ultimately, vehicle performance.

 

 

Note that they mention tire oxidation, and not wheel. I've never seen a wheel corrode here in NY with air in them, used in the summer. Inside, outside, nothing. Year round and in winter? You bet. Hang a wheel weight on the clear coat, it chips, and then salt, etc. eats it away.

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