How Accurate is the Tire Pressure Display Reading?
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Senior Member
Joined: Jul 2013
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2024 E350
How Accurate is the Tire Pressure Display Reading?
So I've used a tire pressure gauge similar to the one pictured below, but I noticed that it always reads 2 psi LOWER than what the tire pressures in the Mercedes TPMS display shows. So if my Mercedes display shows 38 psi then my gauge will show 36 psi. It's been like that on my old W212 and now on my current W214.
My question is which one is more accurate?
I just bought one of those small portable lithium powered air compressors from Amazon yesterday and when I connected it to a tire it showed the same psi that my Mercedes display shows, which is 2 psi above the tire pressure gauge reading.
I know it's only a 2 psi difference, but I'd like to know which reading I should rely on: my tire pressure gauge or my Mercedes TPMS display
My question is which one is more accurate?
I just bought one of those small portable lithium powered air compressors from Amazon yesterday and when I connected it to a tire it showed the same psi that my Mercedes display shows, which is 2 psi above the tire pressure gauge reading.
I know it's only a 2 psi difference, but I'd like to know which reading I should rely on: my tire pressure gauge or my Mercedes TPMS display
MBWorld Fanatic!
Joined: May 2018
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From: Long Island, NY
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
What you need is an electronic (battery) gauge that records and holds the pressure. There are many on Amazon for less than $20.
Hopes this helps.
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Out Of Control!!
Joined: Nov 2018
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From: San Francisco Bay Area
2019 C63CS
The average accuracy of TPMS is around 1-2% across the industry, or +/- 1-3 psi, so they are not super accurate. The resolution is also typically only 1 psi. Mine generally reads 1 psi higher than actual compared to a shop precision electronic tire gauge with a resolution of 0.1 psi. TPMS doesn't have to be very accurate as it's designed to alert you if the pressure drops 20-25%. So if they read slightly higher or lower, that's irrelevant as long as it alerts when the pressure drops 20-25% from the stored reference pressure, which is all the laws require.
Last edited by superswiss; Sep 8, 2025 at 12:31 PM.
