Tire pressure

[Stevejfy]

My Chevrolet TPMS display says I have 32psi, cold tires in the AM.  I then checked the tires with a high quality gauge that I used to use when I autocross and did track days.  That gauge says 35psi.  I am going to go by my gauge not the electronic TPMS.  I will check the tires again soon.  Anyone else notice this issue?

[zzrsouth]

If all 4 wheel sensors report 32psi I think the gage is off.

 

My sensors and gage line up pretty close for cold numbers, see some scatter in the hot pressures.

[Jay P]

The tpms sensor read absolute pressure and the guage reads pressure above atmospheric. Since it looks like you are in Colorado elevation will make it read lower than actual pressure (the higher in elevation the lower the atmospheric pressure). The sensors are inside the tire so no way for them to know outside air pressure. I live at 7000' so mine are off also.

 

Jay

[dw91]

When was your gauge last calibrated? 

[garagerog]

I've got 3 vehicles, 2 of them not older than dirt, but older than the advent of TPMS. The wife's 17 Equinox, the exception. When the tires are cold, they read consistently together. The TPMS registers about 3 lbs. more than multiple gauges I've used and they have been all in the ball park together. Granted, those weren't high-end race shop gauges that would be worth calibrating, but they weren't the $2-3 cheapos either. I inflate the Nox's tires to 35 psi by gauge, TPMS registers 38 psi. Oh, my elevation is about 35 feet above sea level. Last added air to those tires last fall, TPMS just now has dropped down to the range of 35 psi, but it's been hot here all summer, so again come fall I'll have to drag the air hose out. So, I'll open a whole nother can of worms for debate, nitrogen filling of tires. Yes, it's worth it for race cars, in my opinion for the consumer it's just a profit center for dealers. Think about it, the free air all around you and what goes into your compressor is already roughly 79% nitrogen. Although oxygen is slighty more permeable to leaking through rubber than nitrogen, I don't go with the nitrogen hype and expense.

[TheGeek]

On 8/18/2019 at 6:07 PM, garagerog said:

I've got 3 vehicles, 2 of them not older than dirt, but older than the advent of TPMS. The wife's 17 Equinox, the exception. When the tires are cold, they read consistently together. The TPMS registers about 3 lbs. more than multiple gauges I've used and they have been all in the ball park together. Granted, those weren't high-end race shop gauges that would be worth calibrating, but they weren't the $2-3 cheapos either. I inflate the Nox's tires to 35 psi by gauge, TPMS registers 38 psi. Oh, my elevation is about 35 feet above sea level. Last added air to those tires last fall, TPMS just now has dropped down to the range of 35 psi, but it's been hot here all summer, so again come fall I'll have to drag the air hose out. So, I'll open a whole nother can of worms for debate, nitrogen filling of tires. Yes, it's worth it for race cars, in my opinion for the consumer it's just a profit center for dealers. Think about it, the free air all around you and what goes into your compressor is already roughly 79% nitrogen. Although oxygen is slighty more permeable to leaking through rubber than nitrogen, I don't go with the nitrogen hype and expense.

My dealer does not charge for nitrogen.  My truck will sit weeks on end, and I never have to add air to my tires.  So, I do believe in nitrogen.

[dw91]

I didn’t have to touch my tire pressure over 4 years with nitrogen with my last truck or for 3 years with the one prior to that. I’ll keep using it.

 

 

[Sin City Trail Boss]

I have an air compressor in my garage, so free air it is