Tyre pressure monitors

[Philc57]

How accurate are the tyre pressure monitors on our cars ?
I've just bought a new digital pressure gauge from ebay and found ( on checking my tyre's) there is a 3lb to 4lb difference between my new gauge and the mercedes me app.
I've cross checked my gauge with another gauge on another vehicle and both line up , which puts the tpms in doubt for me .
Is tpms accurate or not
Philc57

 

[markjay]

Neither the gauges nor TPMS are particularly accurate. If you go by quroum, then you can work-out which gauge is the odd-one-out. Otherwise you'll need a properly calibrated gouge to measure your own gauge (or TPMS) against.

That said, keep in mind that the TPMS on the car will typically measure the air pressures when the tyres are warm, and this will typically be 3-4 psi higher than cold tyres.

 

[unimog]

You need to reset the TPMS in the dash periodically, I would say at least once a week, more frequently if you do more miles.

 

[Philc57]

Yeah tyres were checked cold and all were 3 to 4lb lower than stated on the app
I'll look into the dash settings when I'm next in the car
Thanks all for replies
Philc57

 

[Philc57]

Just checked my two gauges against a calibrated druck we use here at work to set and check our machine
gauges and they are correct to 0.2 psi..
Will need to find out how to reset tpms in car I think

 

[Philc57]

Update tpms
Looked at the setting of tpms in car this morning and after a reset all is well thanks everyone
New car to me so I'm still learning

 

[Bobby Dazzler]

Update tpms
Looked at the setting of tpms in car this morning and after a reset all is well thanks everyone
New car to me so I'm still learning

Thanks for posting. I’ve never reset mine but perhaps I should