Commercial trucks all have limits on how much they can weigh on the highway. These limits are set forth by the Federal Highway Administration and typically top out at 80,000 pounds when fully loaded with cargo.
Trucks that drive on the Interstate will typically come across weigh stations that are regulated by state officials. These way stations can be either stationary or portable scales along the side of the road and are designed to measure the truck's load at any time when they are hauling freight.