How does the Boxster determine it's speed?

[JayG]

Originally Posted by KRAM36

Why does what matter? The fact that people on the forums don't know the answer to this or that I want to know how the Boxster determines it's speed?

It matters to me because I am going to change the diameter of my tires and I want to calculate how far off my speed will be if the car judges the speed from the tire rotation speed.

Thanks for not answering the question and being a jackass for nothing.

just load waze or a speedometer app on your phone and you can easily see what your speed is relative to the speedo

And Qmulus is far from a jackass