Look at the Big Red Transport history website. Big Red has: 25 tractors 50 trailers In the heavy heavy-duty market, a truck or a tractor is a 10 wheel truck that is ready to hall 8 wheel trailer. The total will make it an 18 wheelers. In the refrigeration trailers, some trailers have a small diesel engine to self sustain the refrigeration independent of the tractor. In general you need trailers more than tractors for efficiency purposes!!!!!