1) Arena prelims 2) Behemoths on the freeway 3) Beltway behemoths 4) Big carriers 5) Big highway rigs 6) Big Macks 7) Big rigs 8) Big trucks 9) Big users of highways 10) Cargo carriers 11) Cargo haulers 12) Certain rigs 13) Certain rnd 14) Certain tournament round 15) Certain tourney rounds 16) Certain trailer trks Found on https://www.crosswordclues.com/clue/semis