FIFTH WHEEL SETTING GUIDE
A reference guide or gauge for setting the position of a fifth wheel coupling (15) upon a tractor chassis bed (16) of an articulated tractor-trailer combination, features an elongate extendible linear bar with one or more juxtaposed elongate marker rules or guides (20), each sub-divided by a series of markings representing indexed relative positions for relative tractor trailer disposition, and related respectively to a distance between trailer (11) front wall and tractor cab (10) rear wall and tractor cab chassis (16) rear end and trailer underside legs (14) or base step wall (17); along with an alignment reference marker (26) for setting in relation to both scales, as an indicator of fifth wheel position to allow operating clearance between tractor (10, 16) and trailer (11). A combination extendible rule is envisaged for both trailer and both factor measurements. Dual considerations of operational clearance to avoid mutual impact or collision and minimizing tailer front wall to tractor cab rear wall clearance for reduced induced, profile or form drag and thus improved fuel economy.