Wheel sensors

[The Gecko_imp]

Two simple measurements with defined precision can still add up to a measurement with more uncertainty, it's called the error chain. With both measurements already demanding a precision of 0.05" or better, and the end of what I called the tube not accessible, this is still a tough measurement.
BTW me too I doubt, that it is the sensor position, just trying to eliminate what I can before wasting money on it.
Thanks