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Received this tire pressure warning this morning. I’m on run-flats. While driving, the pressures for both fronts and rears would match, yet only the FR and RL would stay yellow. I’ve checked and there are no leaks or punctures that I could find. Any help understanding this would be appreciated. 2018 C350WE. Thank you!
See what either your owners manual or the plate that's usually found in the sill of the drivers door says your tire pressure should be at and make sure your tires air pressure actually matches those figures. Be sure you check your tire pressure in the morning before you've driven the car so you get the most accurate tire pressure readings. You should always check your tire pressure readings once per month to be sure your readings are what MB calls for. Typically the tire pressure readings for the front tires are lower than the tire pressures MB calls for for the rear tires.
Bring the air pressure in the rear tires down to 38 or 39 psi ( they are way overinflated) then recalibrate the sensors via the on screen instructions. While the tires are cold.
Gas door tire pressures From my Companion App, shows that both fronts are the same pressure, with the FR being low. This is prior to adding air.
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I added air today and the rears, at 50psi, cleared the error. I also added to the front, both fronts above 41psi, and the FR is still showing low. So confusing!
There's no pre-programmed pressure at which it alerts of low tire pressure. You have to store the tire reference pressure properly. Let your tires cool down at least 3 years, then adjust the tire pressure to normal load as indicated on the fuel door. Then go into the service menu in the instrument cluster, select tires and then reset the TPMS. That will store your current tire pressure as the set pressures. Now it will alert you if the pressure drops 20-25% below the set pressures. If you've never done this procedure before, then you don't know what pressures are set as the reference currently.
But your gas door says 36 Fronts and 41 Rears for normal load. Does it specify it elsewhere for the Hybrid?
the only specification I could find is the gas door…
I’ve never had run-flats either, so I don’t know if the pressures indicated on the gas door account for that. Would tire pressures still be the same for either regular or run flats?
I’ve reset the pressure values (thanks, SuperSwiss!) back to the ‘cold’ values
My MB is your car's great-great grandfather as in 190E but all of my tire pressures on the driver's door sill, the gas cap door and my owner's manual are all the same. I've never had run-flats so I don't know if there's any difference there. I would follow whatever all of the various already noted data points indicate for your car. I think if you have any additional questions, you might check with the service department at your local MB dealership if any of the tire pressure figures for your car vary.
There's no pre-programmed pressure at which it alerts of low tire pressure. You have to store the tire reference pressure properly. Let your tires cool down at least 3 years, then adjust the tire pressure to normal load as indicated on the fuel door. Then go into the service menu in the instrument cluster, select tires and then reset the TPMS. That will store your current tire pressure as the set pressures. Now it will alert you if the pressure drops 20-25% below the set pressures. If you've never done this procedure before, then you don't know what pressures are set as the reference currently.
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