A shipper wants to load a Division 4.2 spontaneously combustible solid in the same trailer as a Class 8 corrosive liquid, pointing out there's room to keep the two shipments 10 feet apart. Is this load legal?

49 CFR 177.848(c)

Spontaneously combustible materials can ignite on contact with air or moisture, and a corrosive liquid leak can trigger exactly that kind of contact or supply the moisture that sets it off. Because the two together create a direct fire-ignition risk, the rule doesn't offer a distance or barrier option the way it does for less severe incompatibilities — this combination is simply forbidden.