Weight allowance limits for commercial truck axles on state roads are determined by states, but there are national weight standards for interstate highways. For example, the limit for a single axle is 20,000 pounds.
On interstate systems, the national limit for tandem axles is 34,000 pounds. The maximum gross vehicular weight is 80,000 pounds. Except for commercial trucks carrying automobiles or boats, there is no overall maximum length imposed. Car and boat haulers are limited to 65 or 75 feet, depending on the trailer connection system. There is no federal limit on vehicle height, although state regulations vary between 13.6 and 14.6 feet.