A burnout occurs when the driver of a car or motorcycle spins the vehicle's drive wheels on dry pavement until a trail of white smoke is generated.
The origins of this act can be traced to drag racing, where burnouts have a practical purpose; drag racing tires perform best at a high temperature, and a burnout is the quickest way to increase the tire temperature. In drag race tracks, there is usually a slightly wet paved space, the 'burnout box', reserved for burnouts.
Burnouts have become a form of serious competition and entertainment in their own right. Considerable prize money or goods are sometimes involved, and cars may even be sponsored or purpose built specifically as a burnout car. Burnout competitions are judged on crowd response, so style and attitude are factors. These contests are particularly popular in Australia but often occur in North America as well.
Burnouts are extremely easy to achieve in a front-wheel drive car where the parking brake works on the rear wheels; all one has to do is hold the parking brake (also known as the 'emergency brake' or 'e-brake' by many) and accelerate. This is because front-wheel drives have the engine's power transferred to the front wheels only, so keeping the rear wheels in place is bound to cause the front wheels to 'grind' against the ground without moving, creating tire smoke.
Burnouts in a rear-wheel drive cars generally require feathering the brakes while holding down the gas pedal with the car in gear. There is a normally a point where the front brakes will prevent the car from moving forward, while the rear brakes don't have sufficient grip to stop the wheels spinning. Drag racers and others that frequently do burnouts in rear wheel drive cars often install devices called line locks in the front brake lines. These devices alow the brakes to be applied and then the pressure in the front brakes to be "locked". The lock maintains fluid pressure on the front brakes, while releasing the pedal frees the rear brakes. With line locks installed, wear to the rear brakes during a burnout is eliminated (a problem with the normal method).
Burnouts are most difficult to perform in four-wheel drive cars due to the fact that all four wheels are given traction. Four wheel drive cars get better initial traction (the engine weight being directly over the drive wheels). Additionally, it requires significantly more powerful engines to break all four tires loose at the same time, also the tires will only spin for a short distance before all 4 tires gain traction. Commonly a four-wheel drive car taking off fast enough to spin or make the tires chirp is called launching but this often leads to a damaged drive-train.
Burnouts are also common in informal street racing, usually for show value. As with all street racing activities, burnouts on public property are illegal in most countries but carry very little fines.