O "scale" vehicles are actually 1:43 (too big), 1:50 (slightly small) and 1:48 (just right). A lot of Plasticville structures are closer to S scale 1:64, so S scale vehicles may look better next to them. Winross makes tractor trailer rigs in 1:64 scale. Do a google search for "1:64 vehicles" for lots of options.
Bob