How come when my front tires were 8 psi low and the back tires were 10 psi low I did not get a low pressure warning? I know the Owners manual says it will warn for significant pressure lost.I would think 8-10 psi would be significant. Maybe it needed to be reset for some reason. I have a 08 335i with run flat tires 225/40-18 front,255/35-18 rear. I aired them up and some of the road noise went away,but still has some slight road noise, typical of run flats. I won't be using them the next time around.
Does it use an actual tire pressure sensor or just comparing one wheel to another using the ABS sensors as my '03 Mini?
The tire pressure warning system on most cars will not register an even pressure drop in all tires. It senses when one tire diameter is significantly different from the others.
Terry is correct when there is a equal pressure drop the sensors in the tire think it just related to a temperature drop. The tpm system is meant for loss of pressure in one tire, make sure after you fill your tires you reset the system.
