Thread: 135 spare tyre
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      07-07-2016, 08:27 AM   #24
champignon's Avatar

Drives: 1M;Z3M Cp;135is Vert, 18 MG M2
Join Date: Jun 2015
Location: Idaho

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Originally Posted by Dackelone View Post
No, I do not have a TPMS sensor in my spare. But that would not confuse the system. The sensors are only activated when the wheel is spinning(on the car). Having a spare with a TPMS would be ok in the trunk. I just did not feel like spending extra money for my spare.
I believe that this may be incorrect for the US cars, using the TPMS sensors in the wheels.

I know from my ownership of Subarus, that if people put winter tires on without sensors in them, that they would get the warning light after driving a few miles. Then, when they parked in their garages (containing the removed summer tires with the sensors still in them) the system would reset and they could again drive a few miles, after which the system would again show the warning light.

I'd imagine that the BMW system for cars having the sensors in the wheels would act somewhat similarly, and if not exactly like that, would still sense a non spinning wheel in the trunk containing a sensor. If the tire was not inflated, then the warning light would go off, just as it would if the tire was not there at all and had been replaced with a non-sensor containing spare of some sort.