9-axle trailers are very specialized trailers. They can come in several axle configurations, but no matter what, they are all designed to handle heavy weights of around 100k to 110k lbs. The 9-axle trailer setup can exceed 100 feet in length bumper to bumper. These trailers almost never haul freight within the legal size limits. So, they require oversize permits and escort vehicles in most, if not all, cases. Because these trailers are so specialized, they are often very difficult to come by and expensive to use.