1. Single Tractor-Trailer: A typical single tractor-trailer consists of a semi-tractor (the cab and engine unit) attached to a single trailer. The overall length of a single tractor-trailer is usually around 48 to 53 feet (14.6 to 16.2 meters).
2. Double Tractor-Trailer: Also known as a doubles or twin trailer, this configuration consists of a semi-tractor pulling two trailers connected by a converter dolly. The overall length of a double tractor-trailer is typically between 75 to 80 feet (22.9 to 24.4 meters).
3. Triple Tractor-Trailer: This configuration is known as a triples and consists of a semi-tractor pulling three trailers connected by two converter dollies. Triple tractor-trailers are usually 100 feet (30.5 meters) or longer.
These are the maximum lengths allowed for tractor trailers on most highways in the United States. Some states and regions may have specific regulations or limitations for longer trailers or certain routes, so it's important to check local transportation regulations when operating a tractor trailer.
