Maximum Descending Speed This is a hypothetical question but I'm curious.  Assuming an endless, freshly paved road with no turns, what would be my maximum speed?  

EDIT
My question is too general so to help I'm adding some extra assumptions:  


19 degree slope like Baldwin St.
Tuck is hands on drops, back horizontal as described in this study
Still air conditions (no head/tail/crosswinds) winds
No special suit, just normal warm weather road kit
The question has been changed since this answer was posted. 

On an 85° grade you would approach terminal velocity for a sky diver of about 120 mph.

It does not need to be endless. You approach terminal velocity pretty quickly.