Physics Suspension Travel

[Storm Rider]

Hi there guys, I give up on this. I have been trying to figure this out exactly, at least since the Physics pack was released. I´m pretty sure that I´m not the only one here.

Can someone explain what is the 0 Design of the Suspension?
Take for example this car:
It´s data for the Front Suspension:

Static Deflection=0.053m
ROD_LENGTH=0.045m
BUMPSTOP_UP=0.122
BUMPSTOP_DN=0.030
PACKER_RANGE=0.120

1- When the car is static on the ground, the telemetry channel for susp travel reads +0.055m (aprox. its calculated static deflection)
2- When the car has its suspension fully extended, it reads +0.013m giving an actual extension travel of 42mm. I just can´t figure out any relation of these numbers to the BUMPSTOP_DN data...

Now, how exactly is this calculated?
Cheers