TPMS vs stick gauge

[Rick#7]

I noticed something weird this morning. I have a stick style tire pressure gauge that I have used regularly for years. It's a cheap gauge so I always accepted that it may not be dead on accurate, but I also assumed it would at least be consistent, meaning if it was off by 2 psi, I figured it would always be off by that amount. Anyway, I used it again today to check my tires and added air to 1 tire to make all 4 read 32 psi. This was after the car sat in my garage all night, so there wouldn't be any temperature variations from driving or the sun hitting 1 side of the car. So from there I took the car out and as soon as I pulled out of the driveway I switched the dash screen to tire pressures and it showed 3 different PSI readings on the 4 tires; left rear was 31, both front were 33, and right rear was 34 (the one I added air to).

I know 1-2 PSI is no big deal, but I was just wondering what is more likely; is my stick gauge reading inconsistently, showing the same PSI on 4 tires when it's actually varying 1-3 PSI, or are the sensors in my tires not reading the PSI consistently from one sensor to the next?

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[Brokestang]

I have the same thing happen to me & not just the mustang but all my cars. By the way I've had my stick gauge since 93!

 

[robvas]

A lot of those stick/pencil gauges are just plain junk. They do have calibrated ones, however.

I just buy the digital ones on Amazon for $15-20. Usually very accurate.

 

[NightmareMoon]

TPMS may not update at the same time for all 4 tires. I’d give it a few minutes.

 

[Skye]

When I received Skye, I had an old stick gauge as well. Something was off though. The stick gauge would read one thing, TPMS, another. I purchased a nice unit from AutoMeter.

https://www.autometer.com/performance-analog-tire-pressure-gauge.html

This gauge and the TPMS are spot on with one another. The stick? It was off by 2 psi / .13 bar.

The AutoMeter unit has memory and a bleed valve on the side. To compliment using that, I have a Milton tread depth gauge.

https://miltonindustries.com/produc...aNicX-tTRjMor9dFtbDVJcfYsIhRXfWx78kCwn8ptQqKx

I always check my tires manually. TPMS is nice and all, but I see it as a warning system more than one for measurement. My TPMS system rounds up or rounds down. For example, 31.5 psi is 32. 31.4 psi is 31. The AutoMeter unit tells me what it really is.

I'll never use a stick gauge again.

 

[MAGS1]

Could also be that the TPMS needs a few miles to recalibrate. Had that happen before, especially after one set of tires sitting in the basement all season. I always check and fill them before putting them on the car, usually takes a little bit of driving before they recalibrate and read properly (and I do the TPMS relearn with the device so it’s picking up the right set of tires right away).

I have both a pencil gauge that I keep in the center console as well as a digital gauge. Both are close to each other, the digital is the most accurate and lines up exactly with the digital gauge/pump that I connect to my air compressor to fill said tires.

 

[luc]

I noticed something weird this morning. I have a stick style tire pressure gauge that I have used regularly for years. It's a cheap gauge so I always accepted that it may not be dead on accurate, but I also assumed it would at least be consistent, meaning if it was off by 2 psi, I figured it would always be off by that amount. Anyway, I used it again today to check my tires and added air to 1 tire to make all 4 read 32 psi. This was after the car sat in my garage all night, so there wouldn't be any temperature variations from driving or the sun hitting 1 side of the car. So from there I took the car out and as soon as I pulled out of the driveway I switched the dash screen to tire pressures and it showed 3 different PSI readings on the 4 tires; left rear was 31, both front were 33, and right rear was 34 (the one I added air to).

I know 1-2 PSI is no big deal, but I was just wondering what is more likely; is my stick gauge reading inconsistently, showing the same PSI on 4 tires when it's actually varying 1-3 PSI, or are the sensors in my tires not reading the PSI consistently from one sensor to the next?

Did you drove the car for a few miles/minutes and rechecked ?

 

[GJarrett]

Another confirmation here that the TPMS needs a couple of miles/minutes to display current psi. I borrowed a calibrated gauge one time to check against my tires pressure dash display and it was spot on. I just trust it now for being plenty accurate.

 

[Rick#7]

Did you drove the car for a few miles/minutes and rechecked ?

I forgot about the system needing a few minutes of driving to update, but I did leave it on the TPMS screen as I drove down the road, the only change I noticed was the 31 PSI tire went up to 32. I switched the screen back to the tripmeter at that point because I wasn't too concerned about it, it was just something that got me curious.

 

[Grimmer]

I've liked this digital gauge I picked up from Lowe's. It has a silicone dome tip that seals a lot more easily and from multiple angles.

It has been within a couple PSI of the TPMS up or down 1psi due to rounding as mentioned previously.

 

[Jerryinpa]

I noticed something weird this morning. I have a stick style tire pressure gauge that I have used regularly for years. It's a cheap gauge so I always accepted that it may not be dead on accurate, but I also assumed it would at least be consistent, meaning if it was off by 2 psi, I figured it would always be off by that amount. Anyway, I used it again today to check my tires and added air to 1 tire to make all 4 read 32 psi. This was after the car sat in my garage all night, so there wouldn't be any temperature variations from driving or the sun hitting 1 side of the car. So from there I took the car out and as soon as I pulled out of the driveway I switched the dash screen to tire pressures and it showed 3 different PSI readings on the 4 tires; left rear was 31, both front were 33, and right rear was 34 (the one I added air to).

I know 1-2 PSI is no big deal, but I was just wondering what is more likely; is my stick gauge reading inconsistently, showing the same PSI on 4 tires when it's actually varying 1-3 PSI, or are the sensors in my tires not reading the PSI consistently from one sensor to the next?

Hi,
I use a Slime digital tire pressure gauge with a built-in bleed valve, let the tire temperature stabilize, in the summer I choose 75F, fill the tires a couple of pounds higher than 32 psi, most digital gauges have 0.5 psi resolution, with the bleeder let a puff of air out until the gauge transitions from 32.5 to 32.0, now your pressure is much closer than a 0.5 pound. Repeat for all tires. When I do this it'll match the tpms pressure in the dash. Of course you have to drive a few miles till all 4 tpms readings update. By then the tires start warming up and the pressure starts increasing.

Thanks, Jerry

 

[Bob Lob Law]

I use a good calibrated tire gauge from my track days(sport bike). So far, my tpms readings have been spot on!

 

[mavisky]

Stick gauges are probably the least reliable form of tire pressure measurement. To hear that one is off is not shocking. They're handy to keep around due to their small size and stick gauge is better than none at all. That being said I'd wager that a good needle gauge or digital gauge combined with actually driving the car for a minute or two to let all the sensors update would result in much more consistent readings across the board.

 

[robvas]

 

[cerbomark]

I must be the oddball. I have three cars and three stick gauges and they can t be more than 1 psi difference if at all from the cars tpms.

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