SRT 10's, Run Flats, and Tire Pressure Warning System

[Bobpantax]

SRT 10\'s, Run Flats, and Tire Pressure Warning System

Recently, I felt that my car's ride seemed a little different. I made a guess that it was from low tire pressure even though there was no warning light on. I brought the car to a gas station and checked each tire. All four were low by four or five pounds. I then asked my local Viper tech about it. He said that the system on the Viper does not warn when all of the tires are uniformly low within three pounds of each other. He also said that the run flats lose air more rapidly than non run flat tires. So, the bottom line is that I am going to start checking the air pressure in my tires more frequently. Any of you experienced the same thing?

Bob

PS. My Magnum SRT 8's system detects low pressure even if it is uniform. We had what we consider a very cold morning down here recently and the Magnum warning system went off. The difference tire to tire was one pound.

 

[Newport Viper]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

Thanks for the reminder. I will check mine tomorow!

 

[Xhlr8n]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

my light stays on even though the tire pressure is correct, anyway to reset them without taking to dealership?

 

[Paul S Lacey]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

You can try reseting the ECU by disconnecting the battery make sure keys are not in the car.

If one sensor is faulty or not connecting to the receiver which is in the dash behind the radio then the light will not go off.

Each sensor needs to be attached to the receeiver by the DRB II (dealer tool) which can confirm each unit is working or find a faulty unit.

After fixing the fauly the light will still show as each wheel need to rotate so many times above a certain speed before the receiver accepts its ok signal.

Hope this helps mine on my SRT was a PITA

 

[PaViper]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

Have you tried filling the tires with Nitrogen. Supposedly, they are less likely to leak down, and are far less likely to be affected by ambient temperature.

http://www.nitrogendirect.com/?gclid=CKX53oaxq4sCFQM6gQodDhMSMg

 

[Andrew/USPWR]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

It's funny you brought that up. I just noticed all of mine, down exactly 5lbs each. The old pilots never lost air.

btw I still have a set of Gen I & II tires for sale. fyi

 

[Bobpantax]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

Have you tried filling the tires with Nitrogen. Supposedly, they are less likely to leak down, and are far less likely to be affected by ambient temperature.

http://www.nitrogendirect.com/?gclid=CKX53oaxq4sCFQM6gQodDhMSMg

1.The Vipertech suggested Nitrogen. It is $10.00 per tire. I would like to hear from those who have tried nitrogen before using it. The logic behind it seems a little flawed since regular air is 78% nitrogen and the stiff character of the run flat sidewalls is probably the source of the problem. Any empirical data out there on nitrogen use?

2. Tire pressure system reset. When I first got my SRTC, the light for low tire went on when there was no low tire. We had to use a combination of computer reset and the donut magnet device on each valve stem, multiple times, to finally get the system corrected. It has worked fine since then. The system on the Viper is the older system. It is not as good as the current SRT 8 system. It seems DC bulk orders many parts and continues to use them until they are used up. For instance, I also had the driver's side window regulator replaced shortly after I got the 2006 SRTC. The part had a 2004 manufacture date on it. So did the new part. Basically, just because we buy a 2006 vehicle does not mean that all of the parts were made in the same model year if the basic car has remain unchanged. My guess is that the 2008 will also have many parts made in earlier years since other than the hood and drive train changes the car is basically the same. I assume that this is SOP for all the car companies.

 

[Racer Robbie]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

I had a RR tire go down and the indicator showed Lo on the dash when the tire had 13 lbs in it. After fixing the tire the chime and readout did not reset until I disconnected the battery cable to the fuse box under the hood. Then everything worked fine.

 

[JonB]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

....Have you tried filling the tires with Nitrogen. Supposedly, they are less likely to leak down, and are far less likely to be affected by ambient temperature............ The logic behind it seems a little flawed since regular air is 78% nitrogen and the stiff character of the run flat sidewalls is probably the source of the problem. Any empirical data out there on nitrogen use?

99.9% of race teams in most venues use Nitrogen. All airlines and USAF use Nitrogen. It is not really any less likely to seep, on a molecular level, but what helps keep the pressure constant is that it will not expand as significantly when heated. And the OXYGEN in ambient air is corrosive to RUBBER and METALS....degrading the tires faster so that OLD tires would seep more with ambient air than with Nitrogen. LOTS OF DATA EXISTS to support this.

If your ambient-air tires seep, it is probably seeping more when they are HOT and at higher pressures. Nitrogen stays close to pre-set pressures at highway tire temps.

 

[Bobpantax]

Re: SRT 10\'s, Run Flats, and Tire Pressure Warning System

Thank you Jon. Interesting. So theoretically, the O2 is the culpret because it expands and increases the air pressure in the tire possibly causing a greater probability of gas escape due to some very small separation of the tire from the rim as opposed to a pure nitrogen environment maintaining a more constant pressure within the tire under varying conditions? This still seems a bit odd based on the chemistry:

Gas Ratio compared to Dry Air (%) Molecular Mass
- M -
(kg/kmol) Chemical Symbol Boiling Point
(oC)
By volume By weight
Oxygen 20.95 23.20 32.00 O2 -196
Nitrogen 78.09 75.47 28.02 N2 -183

Nitrogen is lighter than oxygen. Do you know why it would act in the fashion suggested in the environment being discussed?

 

[SweetRed04]

There are two advantages to Nitrogen: no corrosive oxygen and it is commercially "bottled" and has no moisture in it. The oxygen issue is rather lame since the OUTSIDE of your tires and rims are ALWAYS exposed to it.

The moisture issue is legit, but if you have a large compressor with a dryer on its outlet, I doubt you get much moisture in your tires unless you start with a decompressed tank and are in humid conditions. If your air tank has been sitting for a day, there isn't much moisture comming out of it.

The expansion claims are totally bogus. All gases confirm to the Universal Gas Law. PV=nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the absolute temperature.

There is a more complex van der Waals equation relationship that takes into account molecular size and inter atomic attraction but I doubt there are significant differences between the larger 02 molecule and the N2 molecule - I'd bet that they favor O2.