What's the check tire pressure set point?

tomseeley · October 21, 2012

I may just as well have posted this on any section of this forum, but I have a 2009 Sierra 2500HD duramax, so I'll put it here.

I got a "check left rear tire pressure" message today. I had not driven the truck in a few days so the tires were all cold. I went around to check all four and found all four at 60-65 psi. The Owners' Manual specifies 60 front/80 rear, so 60-65 was ok in front but low in both rear tires.

I have 2 questions:

1. What's the set point for the pressure monitor on any tire? Is the rear set for 80 psi because the manual says I'm supposed to keep the rear tires at 80 psi, for example? I'm trying to find out what pressure the monitor considers low and sends me the message.

2. Why would I get the message for the left rear but not the right rear when both tires were at the same pressure, within a psi or two?

grimmysnr · October 21, 2012

The tire pressure set point should be about 20% less than the factory recommended rating. This is set by the NTSB so it cannot be changed or altered. If your max is 80 psi then the pressure you would get a light at would be approximately 64 psi. The reason you may have only gotten a warning for one tire could just be what the pressure read at the moment it took the reading or it could just be a small glitch. On my 2010 Sierra 2500HD my maximum pressure is 72 psi and I have had one tire be lower than the other but yet the high tire would send a warning. Even during the drive I may not ever get a warning for the lower tire. It is just a finnicky system sometimes but it is also designed with the governments hand so I suppose getting any warning at all is good enough for government work. I usually keep my front tires at the recommended rating and I keep the rear tires about 15% below factory recommended so that I can factor in cold mornings. Unless I am towing anything which is rare anyway, I just keep my tire pressure at the lower part of the spectrum for better traction and ride quality.

HEMICAT · October 22, 2012

I've seen mine at 49 and still no warning message.

idahoruss · October 23, 2012

Your dealer can set your TPMS to the pressure you specify. In my case, I kept the tires from my 2007 and they set the TPMS for my 2012 to 65 psi to match my tire's load carrying pressure, found on the sidewall. Depending on my load, I can go from 55 psi to 60-65 psi with no warning.

They did not charge me for this because I asked for the change when buying the truck. I do not know what they would charge for a "drive-in" request. It is a pretty quick process.

Russ J.

MTPoleKat · October 23, 2012

I have a 2012 2500hd. Can't get my dealer to change theTPMS setting so I've messed around with it to get it as low as I can w/o light going off. 49psi in front tires 60psi in the rear will not trip the light. Mine is the vortec not duramax though don't know if that matters or not.

Hate the TPMS. in all my pickups I've never run over 40psi in my tires, Why feel every crack in the road. Now I just leave it at them pressures but when I'm out in the hills hunting I drop them all to 35-40 psi and deal with the light and hitting the button four times when I start it up.

grimmysnr · October 23, 2012

You got lucky then because for a dealer to alter the pressure outside of what the manufacturer recommends is illegal.

Sent from my DROIDX using Tapatalk 2

sdeeter19555 · October 23, 2012

Mine just did this too...cold weather coupled with a still fairly strong sunshine caused it to oscilate between the two rears. I found that (depending on the gauge), 65psi in the rear is as low as you can go before the DIC indicates a low rear tire. I have not messed with the front.

Sort of sucks because in the winter I like to run about 50 PSI in the rears (unloaded)...

Big Whiskey · October 23, 2012

You got lucky then because for a dealer to alter the pressure outside of what the manufacturer recommends is illegal.

Sent from my DROIDX using Tapatalk 2

Are you sure about that? Dealers do that all of the time. It's very common to install new tires that require a different PSI than the stockers. It may be illegal to turn the TPMS off completely...but I was unaware it was illegal to change the PSI range.

grimmysnr · October 23, 2012

While I can find information stating that disabling it is illegal I could not find anything black and white stating that they can legally lower the pressure. From what I did see and even on a thread I created here sometime back that ultimately it is a liability issue for the dealership and in most cases won't arbitrarily alter the pressure for just anybody. Simply put, if their parent company GM says that the vehicle is rated for X amount of tire pressure and the dealer's/customer's infinite engineering wisdom decides that the pressures should be lower then what happens when that person has some type of accident that may total the vehicle? Not to mention cause a fatality? I could see many lawyers who could spin this in GM's or their clients direction because the vehicle was not operating in a manner that was prescribed by law. I am all for customizing my stuff and I would never tell anybody they couldn't either but people should always assume the risk when they do so even if its just the fact that if somethings happens the customer pays for the incident. I do think that saying every dealer would simply change your pressure at request is false mostly because I attempted to do that with four dealers in my town and they all told me to get bent.

HEMICAT · October 23, 2012

Mine just did this too...cold weather coupled with a still fairly strong sunshine caused it to oscilate between the two rears. I found that (depending on the gauge), 65psi in the rear is as low as you can go before the DIC indicates a low rear tire. I have not messed with the front.

Sort of sucks because in the winter I like to run about 50 PSI in the rears (unloaded)...

I don't understand- why can I run 50 in my rears with no warning message?

idahoruss · October 24, 2012

This quote is from the Tire Review web site:

So, the bottom line here is:

• 49 U.S.C. 30122(b) does apply, but only to the TPMS low pressure/malfunction warning lamp.

• While NHTSA would prefer otherwise, sales and installation of aftermarket tires and wheels – and plus-sizing – is perfectly acceptable, providing your shop does not disable the TPMS MIL.

• Aftermarket tires are still not required to work with factory-installed TPMS.

• If you work with an auto dealer to sell and install wheels and tires on new, untitled vehicles, FMVSS 138 requires that the entire TPMS – sensors and MIL – function as if it were OE.

• If the vehicle owner, after buying replacement tires and wheels, still wants the full benefits of their TPMS, they can take the vehicle back to the auto dealer and have the TPMS reinstalled or reprogrammed to work with their new wheels and tires.

The decal tire sizes are for stock tires and the TPMS must work with the stock tires at the time of the sale. The new owner can replace the tires and/or wheels and the dealer can recalibrate the TPMS to match using the tech tool. There is a lot of information available when searching for TPMS or tread act on the internet.

You will have to find a dealer who is familiar with this law and not so conservative that they will not do the recalibration.

sonjaab · October 24, 2012

A friendly dealer reset my pressure range in my 07 2500 so I

can run all my tires at 50 psi for a softer ride....................

The range for no ses or tpms warning light is 45-55 lbs.

sdeeter19555 · October 24, 2012

Mine just did this too...cold weather coupled with a still fairly strong sunshine caused it to oscilate between the two rears. I found that (depending on the gauge), 65psi in the rear is as low as you can go before the DIC indicates a low rear tire. I have not messed with the front.

Sort of sucks because in the winter I like to run about 50 PSI in the rears (unloaded)...

I don't understand- why can I run 50 in my rears with no warning message?

I can't get below 65 psi with tripping the DIC message. I first thought it was an imbalance between the two sides, but I kept inching up from 60psi until the message went away...65psi.

I will hit up my local dealer, see what they have to say about the whole deal.

topdj · April 5, 2013

what you be the best set point if Im going to a tire with a max PSI of 50 right now I cannot go below 55 rear or 50 front

tryn2lrn · April 20, 2013

Depends on what wheel tire combo you have. 20s are 75rear 65front and 20% is right so that's minimum 60rear 52 fronts. I had the dealer remove the 20s and put the 18s on my truck when I bought it which are 70rear and 60front which work out to minimum 56rear 48fronts. They would only reprogram to the GM specs for the 18" wheel tire combo. Even though I explained technically I replaced the factory installed wheels and tires with something other than what came on it stock. Didn't matter they wouldn't do it. I just wanted another 5lbs lower. I worked around it. Empty there is no need for the backs to be above 50. I have been hauling and towing all my life, I know how to regulate air pressures based on usage.