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Old 09-20-2012, 02:37 PM
jadnashuanh jadnashuanh is offline
Officially Welcomed to the 'Fest
Location: NH
 
Join Date: Jun 2011
Posts: 648
Mein Auto: 535ix-drive GT
In the USA, TPMS are now required on all models (some don't use sensors, but rely on the antilock brakes' sensor to detect variations in wheel rotations). Tire specialists aren't supposed to install RFT without the sensors, and they always come that way from the factory. Did you change tires or wheels sometime along the way? The tire installer may have (mistankenly or fraudulently) taken then out and just put in new 'normal' valve stems. If so, you got screwed. With a tire change, they're supposed to use a new gasket, but keep the TPMS sensor. In the USA, they're around $50 each, so not bad for him to sell to someone later on.

If you go to the vehicle status page, do you have an entry for Tire Pressure? If you do, your vehicle came with them, and somewhere along the way, they disappeared!

It can be quite unsafe to drive faster than the recommendations with a RFT when it is flat, or to drive further than they specify. Without the TPMS, you may not realize it until you try to turn at speed. This can make the vehicle unstable. The max speed when you have a flat with a RFT is moderately low, much lower than your limited access highways. So, at least where I live, it is illegal because of the potential unstable situation if you didn't realize you had a flat - the sensors at least warn you to both slow down, and be more cautious. I do not know if that warning is tied into the vehicle's stability program or engine management system.
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