A big rig truck: a semi-trailer plus the truck or tractor pulling it.
articulated lorry
noun
A tractor-trailer or big rig, consisting of a semi-trailer and a semitruck pulling it; in American English referred to as semi-trailer truck or 18-wheeler.
How often have the words 18-wheeler and articulated lorry occurred in a corpus of books? (source: Google Ngram Viewer )