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For doubles, the heaviest trailer should be placed first, directly behind the tractor. This arrangement enhances stability, improves traction on the tractor drive axles, and reduces the tendency for the rear unit to swing or whip in evasive maneuvers, crosswinds, or on uneven pavement. Placing the heavier trailer at the rear increases the risk of rearward amplification—the “crack-the-whip” effect that can lead to rollovers or loss of control. Proper trailer order goes hand-in-hand with correct converter dolly handling, secure pintle hook connections, and air/electrical line setup (including verifying service and emergency lines and ensuring no cross-coupling). CDL objectives for doubles/triples emphasize inspection of the dolly and fifth-wheel, protection valves, proper bleeding off air before uncoupling, and careful backing (generally avoiding backing doubles when possible). Correct trailer placement is a fundamental planning decision that markedly improves handling and is often checked on knowledge exams and pre-trip discussions.

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