On the AAMVA CDL Manual's rearward amplification chart (Figure 6.1), what does a rearward amplification (RA) value of 2.0 mean for a combination vehicle during a quick steering maneuver like a sudden lane change?

49 CFR 383.115(c) ("oscillatory sway, rollover in steady turns"); AAMVA CDL Manual Section 6.1.2 "Steer Gently," p. 6-1

Rearward amplification is the physics reason doubles and triples are more rollover-prone than a single tractor-semitrailer: the same steering input gets magnified at the back of the rig. Understanding the 2.0 example makes the whole concept concrete — a 2.0 trailer isn't just "somewhat more likely" to tip, it's precisely twice as likely as the tractor itself.