Rear extremity
Rear extremity means the rearmost point on a trailer that is above a horizontal plane located above the ground clearance and below a horizontal plane located 1,900 mm above the ground when the trailer is configured as specified in S5.1 of this section and when the trailer's cargo doors, tailgate and other permanent structures are positioned as they normally are when the trailer is in motion, with non-structural protrusions excluded from the determination of the rearmost point, such as:
(1) Tail lamps;
(2) Rubber bumpers;
(3) Hinges and latches; and
(4) Flexible aerodynamic devices capable of being folded to within 305 mm from the transverse vertical plane tangent to the rear most surface of the horizontal member for vertical heights below 1,740 mm above ground and, when positioned as they normally are when the trailer is in motion, are located forward of the transverse plane that is tangent to the rear bottom edge of the horizontal member and intersecting a point located 1,210 mm rearward of the horizontal member and 1,740 mm above the ground.