White Freightliner Blues.Trying to stay within the caveat in the OP, was trying to get creative but realized both these songs make no mention of what kind of big rig so they don't exactly qualify but still are pretty good songs about trucking. Anyone thing of more that maybe specifically mentions something like a brand of a truck in the lyrics (Mack, Kenworth, Peterbuilt, etc?)
Alabama - "Roll On (18 Wheeler)"
Kathy Mattea "Eighteen Wheels and a Dozen Roses"
I think Mean Dean may disqualify this but he should appreciate that it is the name of a model from Plymouth, I give you:
This one is even before my time,