the federal gross weight limit for a class 8 truck is (combined weight of truck, trailer, and cargo) with axle weights limited to (steering axle) and (tandem axles). truck drivers are responsible for checking their own vehicle's weight, usually by paying to be weighed at a truck stop scale. cmvs are subject to various state and federal laws regarding limitations on truck length (measured from bumper to bumper), and truck axle length (measured from axle to axle, or fifth wheel kingpin to axle for trailers). the relationship between axle weight and spacing, known as the federal bridge gross weight formula, is designed to protect bridges. truck weights and sizes are checked by state authorities at a weigh station or port-of-entry.