A monster truck is a specialized off-road vehicle with a heavy duty suspension, four-wheel steering, large-displacement V8 engines, and oversized tires constructed for motorsports and entertainment uses. Originally created by modifying stock pickup trucks and sport utility vehicles (SUVs), they have evolved into purpose-built vehicles with tube-frame chassis and fiberglass bodies. A competition monster truck is typically 12 feet (3.7 m) tall, equipped with 66-inch (1.7 m) off-road tires, and several tons in weight—those competing in Monster Jam events, for instance, must weigh at least five short tons, or 10,000 pounds (4,500 kg).