Quote:
Originally Posted by JSH
With an indirect TPMS system the computer is just comparing RPM between the wheels. If one wheel starts turning faster than the others the effective diameter is smaller and therefore the tire must be low. (Our you put on a different size wheel) Federal law requires a TPMS to trigger when a tire is 25% below the recommended pressure.
Indirect systems are cheap but they have limitations. My 2014 Jetta Sportwagen at indirect TPMS that failed to warn me that I had a puncture on a gravel road because it doesn't work below a certain vehicle speed. We came back from a 3 day backpacking trip to find a completely flat tire. They also don't work if all your tires are equally low - which is what happens when someone never checks their tire pressure and adds air to make up for the normal loss of air pressure over time.
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HMMM odd. In the 2013 Golf, I have to do the snow tire button if it has my "sort of " chains on, and then it gets pissy if the fronts break loose on ice. Haven't experienced any low speed issues, might have to do an experiment there. The owners manual does hint the system compares all 4 since a long sweeping turn should set it off. It did go off sporadically when I got different profile tires and doesn't seem to have a problem running the spare donut.
It does go off when I swap front to rear and forget to change inflation, I always have to reset after tire position rotation at the tire place.