War II era to compare standard sizes, rather than actual capacities. In 1975, a change in U.S. emission laws required any vehicle under 6000 pounds GVWR to burn unleaded fuel. U.S. pickup truck manufacturers responded with a "heavy half" pickup of over 6000 pounds GVWR. The F-150 had a capacity of over 2000 pounds, compared to 1500 pounds for the F-100. This has led to categorizing trucks similarly, even if their payload capacities are different. The Chevrolet Silverado/GMC Sierra 1500, Ford F-150, Nissan Titan, Ram 1500, and Toyota Tundra are called "half-ton" pickups (-ton). The Chevrolet Silverado/GMC Sierra 2500, Ford F-250, and Ram 2500 are called "three-quarter-ton" pickups. The Chevrolet Silverado/GMC Sierra 3500, Ford F-350, and Ram 3500 are known as "one ton" pickups. Similar schemes exist for vans and SUVs (e.g. a 1-ton Dodge Van or a -ton GMC Suburban), medium duty trucks (e.g. the 1-ton Ford ) and some military vehicles, like the ubiquitous deuce-and-a-half. Class 8 The Class 8 truck gross vehicle weight rating (GVWR) is a vehicle with a GVWR exceeding . These include tractor trailer tractors, single-unit dump trucks of a GVWR over 33,000 lb, as well as non-commercial chassis fire trucks; such trucks typically have 3 or more axles. The typical 5-axle tractor-trailer combination, also called a "semi" or "18-wheeler", is a Class 8 vehicle. Standard trailers vary in length from containers to van trailers, with the most common length being the trailer. Specialized trailers for oversized loads can be considerably longer. Commercial operation of a Class 8 vehicle in the United States requires either a Class-B CDL for non-combination vehicles, or a Class-A CDL for combination vehicles (tractor-trailers). Canada Vehicle classifications vary among provinces in Canada, due to "differences in size and weight regulations, economic activity, physical environment, and other issues". While several provinces use their own classification schemes for traffic monitoring, Manitoba, Ontario, Prince Edward Island and Saskatchewan have adopted the 13-class system from the United States' Federal Highway Administration—sometimes with modifications, or in Ontario's case, for limited purposes. British Columbia and Ontario also distinguish between short- and long-combination trucks. In accident reporting, eight jurisdictions subdivide trucks by GVWR into light and heavy classes at approximately (). European Union and United Kingdom Vehicle categories on a European driving licence include (among others) B for general motor vehicles, C for large goods vehicles, D for large passenger vehicles (buses), and are limited by