Per AAMVA CDL Manual Section 7.1.6, why do doubles and triples require extra caution in bad weather, slippery roads, and mountain driving compared to other combination vehicles?

49 CFR 383.115(e); AAMVA CDL Manual Section 7.1.6 "Adverse Conditions," p. 7-1

"Dead axles" — the non-powered converter dolly axles — mean more of a doubles/triples rig's weight sits on wheels that don't drive and don't necessarily help with traction, which is exactly why the same storm or icy road is more dangerous in a triple than in a single tractor-semitrailer.