Tire pressure question
MBWorld Fanatic!
Joined: Aug 2014
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From: Tennessee
W214 E450
Glad you got it sorted. By the way, those tire temps are pretty hot so I hope that those pressures are a couple PSI higher than your cold PSI values. If not, your reference pressures may not be correct.
Super Member
Joined: Oct 2022
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X214
I just moved here from rural Washington (5 Acre fully fenced piece of thickly wooded heaven, a 100 miles away from the craziness of Seattle), and even more than me, my 2 GSDs are facing the brunt of this heat. Cannot wait for Summer to end, and the heat to moderate a bit.
Super Member
Joined: Oct 2022
Posts: 949
Likes: 355
X214
So I drove out with my car today, and absolutely no TPMS notifications whatsoever. Drove like a charm. So the reset (which took 5 secs to do) worked. Easy solution. Having said that, I need to also state that despite the TPMS notification, the car itself drove with absolutely no problems, and the TPMS stuff was more of a visual annoyance at best.
Thank you, @L1Wolf
Thank you, @L1Wolf
MBWorld Fanatic!
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They are both correct. Read those numbers carefully, especially speed and loading. The correct pressures are presented differently for different circumstances - high loading, high speed, ...
MBWorld Fanatic!
Joined: Aug 2014
Posts: 1,913
Likes: 668
From: Tennessee
W214 E450
So I drove out with my car today, and absolutely no TPMS notifications whatsoever. Drove like a charm. So the reset (which took 5 secs to do) worked. Easy solution. Having said that, I need to also state that despite the TPMS notification, the car itself drove with absolutely no problems, and the TPMS stuff was more of a visual annoyance at best.
Thank you, @L1Wolf
Thank you, @L1Wolf
For background, TPMS has a reference number for each tire. As long as the values transmitted by the sensors are within a percentage of that reference number, everything is fine. If one or more report the pressure outside that percentage window, it will alert on that tire. The recommend cold tire pressures for the car are on a sticker on the inside of the fuel door and are based on the specific tires, vehicle, and load for that car. The TPMS reference pressures should be set to the normal load values at the factory which is 39PSI in my vehicle's case. As the car is driven, the tires naturally heat up due to friction and radiated heat from the road. This will increase the internal tire pressure. Since the TPMS system is a range, it should not cause an alert, but it can if the pressure goes too high.
The fact that all 4 tires alerted at the same time and the reported pressures were at or very close to the recommend pressure, I believe the TPMS reference values were lost somehow. If so, it would do exactly what we experienced. Resetting it put new reference values in the system of whatever the sensors were reporting at that time. If this happens again. I may want to have MB take a look to see if they can figure out why the reference values are being lost.
