Direct or Indirect TPMS

[GenesisRZ]

Does anyone know if the Gen coupe has direct or indirect TPMS? I was under the impression that it is direct but the reason I ask is because I put my winter tires on Saturday and the TPMS light on the dash didn't come on until this morning.

On another note, the Blizzaks work great in the heavy Pittsburgh snow but I am not convinced the speedometer is showing the correct speed (have new 18" wheels but likely different sidewall height on tire). Also, they kill all steering feel, but controlled drifting in the snow is fun.

 

[mcginnpm]

The TPMS sensor is mounted at the valve stem inside the wheel. A TPMS initiator mounted on the vehicle body transmits RF energy to "talk" to the sensor inside the wheel. A TPMS receiver, also mounted on the vehicle body, "listens" to signals from the sensor. I don't know if that qualifies the system as "direct" or "indirect".

 

[OBCT]

I believe all Genesis models have the "direct" type TPMS. Correct me if I'm wrong.

 

[GenDriver]

What is the difference between direct and indirect TPMS?

 

[mcginnpm]

A direct system uses a pressure sensor mounted inside each wheel that "directly" measures the pressure in the tire and transmits it to an external receiver module. In the Genesis that sensor is mounted on the inside of the valve stem.

An indirect system uses a wheel speed sensor (typically part of the ABS) that "indirectly" correlates wheel speed with tire pressure. If your tire pressure gets low, it runs "flatter" thus the effective radius is smaller and the wheel speed (rpm) will be higher for a given speed.

Indirect systems are generally less sensative (a fairly significant pressure loss is required to equate to a significant wheel speed change). Also, if all your tires are "bleeding" down at about the same rate, an indirect system will not pick up the loss in pressure, as it compares differential wheel speeds to detect a low pressure tire.