The maximum length of a combination vehicle is:

The maximum length for a combination vehicle is established by federal regulations and state laws, which often align with these standards. In Arizona, as well as many other states, the permitted maximum length for combination vehicles, such as a tractor-trailer, is indeed 23 metres (75 feet). This applies to the overall length of both the truck and its attached trailer(s).

Understanding this regulation is critical for drivers, especially when planning routes and ensuring compliance with local laws. Longer combinations beyond this limit may not be legal on most roads and could result in fines or other penalties.

The other lengths presented in the options do not conform to the established limits for combination vehicles as recognized in Arizona's transportation laws, which is why they are not valid choices. Ensuring that the configuration of your vehicle remains within the 23 metres limit is key for safety and legal operation on the roadway.