Some of the old warehouse buildings that I've been inside of had wood floors strong enough to support forklifts, so I would imagine that they would support a pickup. They had full size
SYP 2 x 12 floor joists (not dimensional lumber), on 12" centers, supported by a beam about every 12 - 14'. The beams were also supported about every 12'. On top of the joists were 2 layers of 1" boards, ...