TPMS ACCURACY

[KSOTI]

Just wondering what people's experience is regarding the accuracy of the tire pressure monitoring system in the Ram? My display consistently reads @ 4lbs higher than the what I manually set the tire pressure to using 3 different reliable tire gauges to confirm the PSI. I want to trust the TPMS but have a hard time believing all 3 of my tire gauges are inaccurate by exactly the same amount especially when I have checked 2 of them on a calibrated air source........

 

[Cueva del Osos]

My TPMS seems to be running 3# heavier than my gauge/compressor. I've also noticed that my compressor takes the tires to the 36psi on the door sticker VERY quickly...but if I turn off the air and then restart it, they read 34-34.5#. I have to cycle the compressor about 4 times to get a true 36#. I don't have this issue on our Subaru or the travel trailer...but can't for the life of me imagine what could be different about the tires on the Ram.

 

[Neurobit]

Just wondering what people's experience is regarding the accuracy of the tire pressure monitoring system in the Ram? My display consistently reads @ 4lbs higher than the what I manually set the tire pressure to using 3 different reliable tire gauges to confirm the PSI. I want to trust the TPMS but have a hard time believing all 3 of my tire gauges are inaccurate by exactly the same amount especially when I have checked 2 of them on a calibrated air source........

Mine also runs about 3-4 lbs. more than what my Joe’s Garage monitor displays. I trust my JG gauge over TPMS.

 

[Glenn54]

My TPMS is about 2 lbs off. It's close enough to tell me if there's a problem.

 

[Neurobit]

My TPMS is about 2 lbs off. It's close enough to tell me if there's a problem.

Yep. That’s how I look at it.

 

[taz2016]

I guess I got lucky, my TPMS is within 0.5 psi of my 2 electronic gauges.

 

[snj1013]

My TPMS readings are within an pound of my Michelin digital gauge.

 

[knightro84]

With the tires cold my TPMS is dead on both of my gauges (one digital and one not digital). Obviously when driving and the tires heat up, the TPMS will read a few pounds higher.

 

[Billet1500 4x4]

My TPMS is about 2 lbs off. It's close enough to tell me if there's a problem.

Same here, TPMS reads 2 lbs higher than my gauge that I carry in the center console. Just like you, I think it's close enough for it to warn me if there's a serious issue.

 

[JJRamTX]

I have to think that the size of the tires would contribute to the differences due to overall air volume variances between tire sizes. I am guessing that an 18" tire would have less volume than a 22" tire which could contribute to the TPMS variance.

 

[snj1013]

I have to think that the size of the tires would contribute to the differences due to overall air volume variances between tire sizes. I am guessing that an 18" tire would have less volume than a 22" tire which could contribute to the TPMS variance.

Hmmm, the TPMS sensors are measuring pressure, not volume.....Not a valid response.

 

[JJRamTX]

Hmmm, the TPMS sensors are measuring pressure, not volume.....Not a valid response.

Let me clarify. The temperature changes would have a more significant impact when there is more volume of air expanding, therefore causing a greater pressure difference at higher temperatures.

We find that temperature and pressure are linearly related, and if the temperature is on the kelvin scale, then P and T are directly proportional (again, IF VOLUME and moles of gas are held constant)

 

[Billet1500 4x4]

Let me clarify. The temperature changes would have a more significant impact when there is more volume of air expanding, therefore causing a greater pressure difference at higher temperatures.

We find that temperature and pressure are linearly related, and if the temperature is on the kelvin scale, then P and T are directly proportional (again, IF VOLUME and moles of gas are held constant)

The is true the formula would be P1V1/T1 = P2V2/T2. However for constant volume the V1 and V2 drop out of the formula and pressure and temperature for a constant volume for the same media will not be affected by differences in volume. Meaning it doesn't matter if you have 1 litre of air or 10 litres of air the same differential temperature will result in the same differential pressure for both systems.

 

[MrCuervoRacing]

Ive had the same issue 3 to 4 psi off

 

[bigoldthor]

Reopening an older thread.

My TPMS is almost exactly 3 lbs *less* than my analog tire gauges. I have two (both Slime brand...one is brand new, liquid filled, and the other older but very accurate.) Today, I very carefully filled each tire to 42 psi, and the TPMS measured exactly 39 psi for each. Am planning to run them over the weekend and check them periodically under different conditions to see how it varies.

 

[Bubba33]

I dont know how accutate, but like the way it honks when they are at 36

 

[SD Rebel]

I have a gauge I believe is pretty accurate, my truck reads about 2 psi higher.

 

[bigoldthor]

So I got bored last night and went out to the garage too play with tire pressures. Turns out, my Slime gauges aren't really that close to each other. Here's how they all compared on cold tires in the garage. (The inflator gauge is a basic Campbell Hausfeld I got at Walmart a few years ago, works fine.)

1. TPMS - 44 psi (all four tires)
2. Inflator gauge - 44 psi
3. Small Slime dial gauge - 41 psi
4. Liquid-filled Slime dial gauge - 48 psi

It doesn't really matter to me which one is technically the most accurate as long as I know the delta when checking. I am quite surprised though to see a 17% variance between the two supposedly "good" dial gauges.

Are digital gauges any better? Are there brands out there that are considered to be the "best" for the everyman?

 

[bigoldthor]

These were the gauges, FWIW:

Cambell Hausfeld:

Slime Mini Gauge:

Slime Pro-Series Liquid Filled:

 

[Jako]

So I got bored last night and went out to the garage too play with tire pressures. Turns out, my Slime gauges aren't really that close to each other. Here's how they all compared on cold tires in the garage. (The inflator gauge is a basic Campbell Hausfeld I got at Walmart a few years ago, works fine.)

1. TPMS - 44 psi (all four tires)
2. Inflator gauge - 44 psi
3. Small Slime dial gauge - 41 psi
4. Liquid-filled Slime dial gauge - 48 psi

It doesn't really matter to me which one is technically the most accurate as long as I know the delta when checking. I am quite surprised though to see a 17% variance between the two supposedly "good" dial gauges.

Are digital gauges any better? Are there brands out there that are considered to be the "best" for the everyman?

I believe Milton stick gauge has been around forever and is reliable. I bought one the other day and the Milton, Slime and TPM coincide. I have had batteries die on the digital, some you can replace the battery and some you can't. Eventually, Warren Buffet and the likes will have control of the tire gauge market and none will have a replaceable battery.
Anybody remember when you could replace the "rubber" portion of the wiper blade for a few dollars or you could get 7 years out of a battery?