What is the overall length of a tractor and trailer?

That depends on the length of the power unit and the weight of the trailer. With a Kenworth W900L with a 265" wheelbase and a 53' stepdeck trailer, I had an overall length of 77 feet. With a Volvo VNL730 and a 48' flatbed or stepdeck trailer, I was right at about 67 or 68 feet. Heavy haul combinations can be significantly longer, but 65 to 78 feet would be about the norm for an over-the-road regional or line haul tractor pulling a single trailer.