Tire inflation (PSI) range for offroading?

[H3 Hummer]

When I went off-roading last weekend, the Park Ranger told me that I would get much better traction if I took some air out of my tires. I asked him about what level and he said 15 - 18 PSI.
His tires looked about the same size as my H3 (if that matters).
That tire pressure seems real low but the idea for flatter, larger foot print makes sense. If that range is true why does the Hummer beep at me under 25 PSI? Is that warning feature only for highway driving? What should the PSI be for off-roading driving? 32 - 33 inch tire size.

[H3 Hummer]

When I went off-roading last weekend, the Park Ranger told me that I would get much better traction if I took some air out of my tires. I asked him about what level and he said 15 - 18 PSI.
His tires looked about the same size as my H3 (if that matters).
That tire pressure seems real low but the idea for flatter, larger foot print makes sense. If that range is true why does the Hummer beep at me under 25 PSI? Is that warning feature only for highway driving? What should the PSI be for off-roading driving? 32 - 33 inch tire size.

[HummerNewbie]

Don't know if that is the correct PSI or not but the sensor will always beep at you under a certain PSI. I am hoping someone figures out how to turn it off. These sensors are required on all vehicle as of 2006 I believe.

[Hummer Guy]

looks like you've got the off-road suspension w/ the bigger tires...those have rim protection so you can air them down and the tires wont slip off the wheel (as easily anyway)...airing down tires is a smart idea for some off-roading, which is why in an H1 you can inflate and deflate from inside the truck via an air compressor...

[PARAGON]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by HummerNewbie:
Don't know if that is the correct PSI or not but the sensor will always beep at you under a certain PSI. I am hoping someone figures out how to turn it off. These sensors are required on all vehicle as of 2006 I believe. </div></BLOCKQUOTE>Ok, surely somewhat had some forethought with this. Any time traction is decreased lowering tire pressure will provide better traction, hence the H3 being an off-road vehicle it should be expected that one will be lowering the pressure.

How does this crap work? Is it when you put the key in, put it in drive, at a certain speed. GM should have something that cuts it when the truck knows you are offroad or all 4 tires are down or something.

[f5fstop]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by HummerNewbie:
Don't know if that is the correct PSI or not but the sensor will always beep at you under a certain PSI. I am hoping someone figures out how to turn it off. These sensors are required on all vehicle as of 2006 I believe. </div></BLOCKQUOTE>Ok, surely somewhat had some forethought with this. Any time traction is decreased lowering tire pressure will provide better traction, hence the H3 being an off-road vehicle it should be expected that one will be lowering the pressure.

How does this crap work? Is it when you put the key in, put it in drive, at a certain speed. GM should have something that cuts it when the truck knows you are offroad or all 4 tires are down or something. </div></BLOCKQUOTE>

GM, like all other manufacturers are obeying Federal Regulations, and those regulation do not allow for deviations to allow for off-roading, or at least I can't seem to find a deviation.
Instead of blaming GM, write your representative in DC, and complain. Jeep/Ford, all of them will probably have the same problems with their '06 models.
The reason for this regulation was the Ford/Bridgestone fiasco.
Ford had the recommended pressure 4 psi lower than recommended by Bridgestone, most of the rollovers were in hot weather, tires were under inflated, as most are on the roads these days, and the vehicles were overloaded. Under inflated tires, overloaded SUVs, hot weather, interstate travel...they were accidents waiting to happen.
So, due to a bunch of idiots who never check their tire pressures, we all are now paying the price; monetarily and mentally.

As to turning off the system, not sure if it can be programmed off anymore due to the Fed. Reg (older cars could have it programmed off). The sensors in each wheel send an RF signal to the remote control (keyless entry) module, which in turn signals the BCM via a class 2 serial data feed, and if required, the BCM signals the instrument cluster to notify the driver of a problem, while it makes the noise.

[PARAGON]

No, actually I blame GM. The NHTSA does not require it to operate at all times and does not specifically say that there can't be something used to consider what the vehicle is doing.

As a matter of fact, if I remember correctly, the NHTSA allowed 2 types of pressure monitoring. One that actually measure the pressure itself and the other that measures harmonic frequency and/or uses wheel speed sensors from ABS or something along those lines. The second type would require it to operate only at a higher speed which is what should happen with off-road capable vehicles, at least.

So, good job sticking up for the employer, but GM knew this regulation was coming a long time ago and could have prepared better for it. Passing the buck won't cut it here. Just the same with DC/Jeep, Ford and the imports that are built for off-road.

Just so happens the H3 is the first that I have heard of that has the system and it seems to not accomodate.

[f5fstop]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
No, actually I blame GM. The NHTSA does not require it to operate at all times and does not specifically say that there can't be something used to consider what the vehicle is doing. </div></BLOCKQUOTE>
Please, supply me with the exact NHTSA regulation that states this (rhetorical question since I will answer). The regulation does not actually state GM cannot add a switch for off-road purposes; however, in this day-and-age of our great court systems, GM and other manufacturers are probably a little gun shy in installing a switch that would enable someone to turn off something required by a Federal Regulation. Most of the car manufacturers are tired of being sued for even those mistakes created by the operator of a vehicle. Even if GM wins, they lose millions to defend these types of lawsuits. Therefore, installing such a switch would open GM up to liability. Litigation costs are passed onto the consumer. (As for how long they are to operate, see the reference under the actual Federal Regulation at the bottom of this message.)
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
As a matter of fact, if I remember correctly, the NHTSA allowed 2 types of pressure monitoring. One that actually measure the pressure itself and the other that measures harmonic frequency and/or uses wheel speed sensors from ABS or something along those lines. The second type would require it to operate only at a higher speed which is what should happen with off-road capable vehicles, at least. </div></BLOCKQUOTE>
You do remember correctly; however, you are living in the past; to be exact, prior to 2003. You are remembering the first regulation (issued May 2002 and required by the Federal TREAD act) issued by NHTSA that required tire pressure monitoring system in vehicles staring with the 2003 model year. Problem is that a NY Federal Appeals Court ruled the regulation invalid in 2003, due to the averaging system you mention; requiring NHTSA to go back and rewrite the regulation. The new regulation (written as 49 CFR, Parts 571 and 585), was not approved until April 8, 2005, with an effective date of September 2005 (cannot remember the exact date).
The averaging system you mention, that was ruled invalid by the Federal Court was not accurate for determining a low pressure in one tire. This inaccuracy was not due to the system itself; this was a system that had been used on many cars in the late eighties to early nineties. However, there was one large fault, and that fault was the operator/owner of the vehicle. Since the systems operated by sensing a difference in tire rotation between the four tires, it could not signal that all the tires were low. Therefore, if all the tires were running at 20 psi, but were supposed to be at 30 psi, the tires were operating at a dangerous pressure. (NHTSA, in June 2005, conducted a survey of 11,500 vehicles that indicted 26 percent of passenger cars and 29 percent of light trucks had at least one tire that was 25 percent or more below recommended inflated pressure.
Therefore, with the tires at 20 psi, the owner loads up the vehicle 20% over the maximum load, and heads out across the desert on a 100-degree day, there is a good chance they will not reach their destination. Low-pressure tires flex, this flex creates friction, friction creates heat, and that plus a nice hot road with nice hot ambient temperatures create the tire’s carcass to eventually give out and go boom. Best scenario is a flat tire, worse scenario is a rollover and people are killed. Therefore, this type of system was excluded from the future regulation.
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:So, good job sticking up for the employer, but GM knew this regulation was coming a long time ago and could have prepared better for it. Passing the buck won't cut it here. Just the same with DC/Jeep, Ford and the imports that are built for off-road. </div></BLOCKQUOTE>
Thanks for the compliment, but I would stick up for any car manufacturer when it comes to what I consider ridiculous Federal Regulations. The manufacturers knew the regulation was coming, and then it was changed. They also knew there were systems being used and newer ones that were available that they were going to use when the regulation took effect. However, like I stated earlier in this message, due to our litigious society, I believe the manufacturers are a little leery of installing something that would allow the system to be compromised, and in fact, in some courts, it might even be ruled illegal, since it would be up to the consumer to turn the switch back to allow the system to operate. Remember many Juries like to side with the little person who is suing the “big pocket” manufacturer, even if it is what I would classify as a frivolous lawsuit.
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
Just so happens the H3 is the first that I have heard of that has the system and it seems to not accomodate. </div></BLOCKQUOTE>
This statement is a bit confusing from someone who appears to keep up with technology, so I might not be interpreting it correctly, and if I am incorrect in my assumption, I apologize. It appears you have not kept up with tire pressure-monitoring systems that have been used for many years. This type of system has been used in Corvettes since they started running runflat tires, and GM has had them installed in other cars such as Cadillac, prior to the regulation taking affect. Mercedes, Porsche, BMW also use separate sensor systems; I could go on-and-on.
(My 2003 Vette has a system that not only detects under inflation, it also detects over inflation. It will signal at less than 25 psi and greater than 36 psi. Originally, it was designed due to the runflat tires that could have zero pressure and yet look just like the other tires with 30 psi. However, many Vette owners, me included, pull the noisy, hard riding runflats off the car and install better tires, and we use the monitoring system to let us know if we have a slow leak that needs a patch/plug.)
Only new thing about this system (H3) versus the one on my Vette is that this system allows for self-learning of the sensors. On my Vette, if I switch sensor locations on the car, I have to use a magnet to recalibrate the sensor to that corner of the vehicle. Not really a problem since the tires cannot be rotated (17” front/18” rear). The C6 Vette requires a RF frequency generator to calibrate the sensors to each corner of the vehicle.
The system used on the H3 can utilize this same frequency generator to calibrate a sensor to each corner of the vehicle; however, if also allows for the computer to reason after a set mileage to recognize which sensor is at which wheel. This is primarily due to the spare, which has a sensor, but the sensor is not monitored until it is installed on an axle. Therefore, if you rotate the tires, or use the spare, you will receive a message that indicates there is a problem with the system, however, after a set amount of miles, the system will re-calibrate itself, turn off the message, and monitor the system as required by Federal Regulation.
The Federal Regulation itself:
Basically, the regulation states that vehicles beginning with the 2006 model year, must have a system that uses independent sensors that can detect when ONE or MORE of the vehicle’s tires are greater than 25 percent below recommended inflation pressures of the tires on that particular vehicle. However, the actual Regulation has a phase-in period that requires 20% of 2006 vehicles to have the system, 70% of 2007 vehicles, and 100% of 2008 vehicles.
The system must signal when a tire (or any number of tires) drops 25 percent below the recommended inflation pressures for the tires on the vehicle. So, if the recommended pressure is 30 psi, the sensor should signal at 22.5.
The system is only required to work with original tires and rims. SEMA and the auto manufacturers pushed this requirement. It would be next to impossible to certify a system to operate on all rims manufactured, and especially impossible to certify on rims not manufactured at the date of certification. From SEMA’s point of view, it would be too costly for rim manufacturers to comply. From the auto manufacturer’s point of view, it would be next to impossible to comply. As for tires, unless the tires are extremely low profile and the sensors are required to be removed due to clearance issues, these sensors should work with almost any replacement tire made.
The detection period is a maximum of 20 minutes. Meaning the system can be calibrated to ignore a low reading for up to 20 minutes. This will help to prevent the early cold morning under inflation syndrome. Since tire pressures drop one degree for each 10-degree drop in air temperature, this will help reduce the drives to the dealership when a tire is low. If your sensors are programmed for 25 psi and you park the car at night and it is 60 degrees outside, and your tire pressure is at 26 psi, and you get up the next morning and the ambient temperature is 40 degrees, your tire pressure will read 24 psi. If the system is allowed to wait twenty minutes before signaling, the tire will most likely warm up as it is driven and go above the warning set point of 25 psi.
There are also requirements in the final ruling that specify indicator light color, location, message warnings, etc. If anyone is interested in reading this document, refer to the CFR and have fun.
I apologize for the long post.

[PARAGON]

First, I'll end your confusion. The H3 is the first vehicle I have encountered that is required to have the NHTSA mandated monitoring system and also goes off-road. Obviously the vette does not qualify and I am quite aware of previous monitoring systems.

The problem here is that this system is not separate and is tied to the data bus and can be programmed and it's the programming that I find fault with. You spent way too much time on an oversimplification of the issue.

Also, you are simply providing the ammunition for my argument by providing the parameters by which the monitoring system does not update and alarm. Another set of parameters SHOULD accomodate, either when the truck is placed in LO-Locked or either use vehicle speed as the determiner. It's really that simple.

So, to go all the way back to my original statements and coupled with your comments, I fail to see why one should be getting the warning when aired down while off-road and if they are getting the warning why someone didn't have the forethought to program something to accomodate what the vehicle was designed for.

[f5fstop]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
First, I'll end your confusion. The H3 is the first vehicle I have encountered that is required to have the NHTSA mandated monitoring system and also goes off-road. Obviously the Vette does not qualify and I am quite aware of previous monitoring systems. </div></BLOCKQUOTE>
Put that way, I understand your statement.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
The problem here is that this system is not separate and is tied to the data bus and can be programmed and it's the programming that I find fault with. You spent way too much time on an oversimplification of the issue. </div></BLOCKQUOTE>
No, I replied to a thread that had statements made that were inaccurate. If it was too long, you didn't have to read it. However, I felt that your statements about the averaging system, the ambiguous statement about sensors, the sarcastic remark about my employer, etc., required answering.
Let's get one thing straight, I am not here to argue; however, if I read something that is wrong, I will try and correct the inaccuracies made by those who THINK they know the laws and regulations of this country. (Sorry, law school does that to someone.)
Now, back to your statements and questions.
Yes it is tied to the data bus used between computers, it was only logical to use this type of system to save costs by using existing technology and systems already installed on the vehicle.
However, I must stress again, will any manufacturer take the risk of a large liability law suit just to suit a few off-roaders? I know that personally I would not.
Remember, installing the switch would allow anyone to turn the system off. This includes the people who never check their tire pressures, the same people who roll over in their SUV. For those reasons, why would any manufacturer open themselves to this type of liability. The H3 will not be a primary off-road vehicle. This forum is small so it is a poor judgment of how many will actually off-road this vehicle. The majority of these vehicles will never see off-road conditions; same as the H2.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
Also, you are simply providing the ammunition for my argument by providing the parameters by which the monitoring system does not update and alarm. Another set of parameters SHOULD accomodate, either when the truck is placed in LO-Locked or either use vehicle speed as the determiner. It's really that simple.

So, to go all the way back to my original statements and coupled with your comments, I fail to see why one should be getting the warning when aired down while off-road and if they are getting the warning why someone didn't have the forethought to program something to accomodate what the vehicle was designed for. </div></BLOCKQUOTE>
To utilize vehicle speed or 4-wheel LO, would not satisfy the requirements you ask for.
Every year, I off-road in the deserts of the southwest; primarily in and around Moab, UT. On these trips I will lower my pressures but I do not necessarily stay in 4-wheel LO, I switch between HI and LO depending on the conditions I come across while on the trail. I also exceed speeds of approximately 35 mph at times while in HI. I do not want to have to stop and inflate or deflate the pressures on the same trail; too time consuming and not worth it.
Therefore, this type of system might be just as aggravating as not having it altogether. Besides, what speed to you set parameters?
I believe, but can't say for sure, all other off-road vehicle manufacturers will have the same complaints from serious off-roaders. All I can say is I will have to learn to live with it, or not deflate my tires.
As for our conversation, as far as I'm concerned it has now ended. I have no desire to drag this forum down to the level of arguing with a complete stranger. So, have a great day, and maybe you can see my point of view, as I see yours, and I will be aggravated as you are when reducing tire pressures (if I reduce tire pressures), and we both will have to learn to agree to disagree.

[PARAGON]

I'll tell you what. I'll forego the argument, though I would have quite the fun discussing this.

Just be careful on your assumptions. First, you have no idea who it is on the other end of the computer cable and I, personally, have no horses in this race. I have certainly never spent any time in law school and I rarely post inaccuracies. This simply is not and will not be an issue for me. It will be fixed by the time I buy my next Hummer. But suffice it to say, that if your arguments were the true basis for the actual reasoning, well, then, even more heads would be rolling at GM.

[H3 Hummer]

Damn, I just wanted to know if I should put 20 PSI or not.

[PARAGON]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by H3 Hummer:
Damn, I just wanted to know if I should put 20 PSI or not. </div></BLOCKQUOTE>STFU

20lbs is probably an average. This all brings up another question and I guess since no one has mentioned it yet they haven't. But has anyone seen the Hummer branded Staun Tire deflators in their tool kit or whatever. What about the '06 H2s. Hummer cut a deal with Staun to put them in the tool kit with the Hummer logo on the little leather case they come in. Anybody seen these yet?