aansonsit

because , today.... change snow tires @ tire shop and check inside a rim hv not a sensor inside , u guys ur C is same with me?(in Canada)

peabers

That is now what I would have expected.

phs

I believe that the MB system is a "passive" monitoring system, ie., it measures the relative rotation of all four tires to check for differences in diameter(~tire pressure). It does not actually monitor tire pressure per se. That is the reason why there is no pressure sensor with the rim. That is my understanding. The "active" system actually measures the individual tire pressure of each of the four tires. The disadvantage is that the sensors run on batteries and the batteries have to be replaced eventually. There might be some systems in the market that are battery free.

V8 AMG

This is my understanding too and I have mentioned it on another thread re: tire pressure monitoring system on our W204s. Strange thing is, a few members of this board have claimed that they have a sensor inside their rims.

RLE

<<This is my understanding too and I have mentioned it on another thread re: tire pressure monitoring system on our W204s. Strange thing is, a few members of this board have claimed that they have a sensor inside their rims>>

You are both wrong. Where does all this crap come from, anyway? I have the sensor from my C300's RF wheel right here on my desk because it got loose inside the tire and was removed until a new one is installed at the first (and last) dealer checkup.

What does it take to convince you guys, anyway?

And I finally got a real sensor price from the dealer today since I will be buying four of them for my winter tire wheels.

$90 each which is stlll too much since Tire Rack sells them for $74.50. They are made by Schrader.

<<Originally Posted by phs>>
I believe that the MB system is a "passive" monitoring system, ie., it measures the relative rotation of all four tires to check for differences in diameter(~tire pressure). It does not actually monitor tire pressure per se. That is the reason why there is no pressure sensor with the rim. That is my understanding. The "active" system actually measures the individual tire pressure of each of the four tires. The disadvantage is that the sensors run on batteries and the batteries have to be replaced eventually. There might be some systems in the market that are battery free.>>

The sensors contain 8-year batteries which cannot be replaced since the unit is sealed. When they die you get to buy new sensors.

nikels

i've mounted snow tires onto the rims that came with the car .. i was going to "reset" the TPMS but never actually got around to it..hasn't given me any warning messages.. i did however flip thru the OM and noticed it mentioned something about a "passive" rotational speed measurement.. and that this was for "Canada Only". Perhaps the canadian versions only have the rotational measuring system, and not the TPMS whereas it exists for the US versions.. if that's true then the canadian mercedes website is falsely advertising TPMS as it's stated in the specs pages.. unless they just mean it as a general term for the passive system..

RLE

<<i've mounted snow tires onto the rims that came with the car .. i was going to "reset" the TPMS but never actually got around to it..hasn't given me any warning messages.. i did however flip thru the OM and noticed it mentioned something about a "passive" rotational speed measurement.. and that this was for "Canada Only". Perhaps the canadian versions only have the rotational measuring system, and not the TPMS whereas it exists for the US versions.. if that's true then the canadian mercedes website is falsely advertising TPMS as it's stated in the specs pages.. unless they just mean it as a general term for the passive system..>>

While pricing sensors today the parts counter guy reminded me that tire pressure measuring systems are required for '08 cars sold in the US. I had forgotten about that which may explain why the Canadian cars have a different and cheaper arrangement.