How does TPMS work?
How tyre pressure monitoring works
Each method of tyre pressure monitoring uses a different mechanism to determine low pressure situations.
Direct TPMS
Each tyre has a sensor that is able to gauge the pressure and the heat of the tyre. These sensors offer their data in real-time and send it to your dashboard via wireless communication. Direct TPMS can identify which tyre is low to a range of 1 to 2 PSI.
Indirect TPMS
Cars are integrated with a system called ABS which has a set of wheel speed sensors. These sensors monitor the rotational speed of the tyres. A tyre that is under-inflated has a smaller diameter than the others and will rotate faster than its correctly inflated counterpart. This system cannot identify which tyre is low.
Critical limitations
25 percent below the recommended pressure is the threshold at which most systems will trigger a warning. By this point, the tyre is significantly under-inflated. TPMS is a safety backup, not a replacement for monthly checks of your tyre pressure.