A doughnut or donut is a maneuver performed while driving an automobile. Performing this maneuver entails rotating the rear of the automobile around the front wheels in a continuous motion, creating (ideally) a circular skid-mark pattern of rubber on a roadway and also causing the tires to smoke considerably.
Doughnuts are more easily performed on wet surfaces and also in the snow. When performed in the snow it is more often done to have fun than it is to make an earnest attempt at creating the circular skid mark pattern.
In the Australian outback, doughnuts performed in the dust or mud areas of land are colloquially referred to as "circle work". Displays are usually performed at Bachelor and Spinster Balls.
To perform a doughnut
A rear-wheel drive car with manual gear-change is required. Turn the steering wheel fully left or right, select first gear, with the clutch still depressed increase the revs well above the maximum torque point which should be between 3000-5000rpm for petrol engines. For "smokey" results take the engine speed to just below the rev limit. Holding it there pop the clutch and floor the gas. The revs should be kept as high as possible and should not drop below the engine's maximum torque point. When the revs drop, the clutch can be depressed allowing the engine speed to "shoot" up and then let go at once, enabling one to keep the wheels spinning. Word of CAUTION, this habit puts a lot of strain on the drive train, avoid doing this on asphalt or any other hard surfaces and don't expect the rear tires to last as a "hard core" doughnut on asphalt will burn them out in anything from 2 to 15 minutes, depending on the power of the car and aggressiveness of the spins.
Advanced or alternative techniques
Once someone who has gained suitable experience doing doughnuts doing just a plain old doughnut is rather boring and may want to add another element to show off skills or wow a crowd.
Standard carA standard car can be one commercially available or a champion event car that has no "auto pilot" controls, unlike specialised doughnut cars. With a standard car you can't do much more as you need access to the accelerator pedal to perform the stunt. One such stunt could be to roll down the drivers window and sit on the door frame with your body and one arm and leg outside and the other arm and foot on the accelerator and steering wheel. As the gear stick and clutch pedal are out of reach the car would need to be moving before the stunt. Once ready the throttle is pumped to initiate and keep the car rotating at the correct speed, for added effect waving to the spectators. For left-hand drive cars it goes anti-clockwise and for right-hand drives clockwise. This ensures that the centrifugal force throw the driver toward the car rather than away. Occasionally drivers open the door and hold on to the roof and door frame, this carries a higher risk.
Specialised carA specialised car is usually a champion event car that has been given a type of auto pilot control that locks the steering wheel and throttle allowing the driver to perform more daring, but also more dangerous, doughnuts. To initiate the doughnut the technique is the same but once achieved the steering is held in place and the throttle is locked at the maximum allowing the driver to release the controls letting the car carry on by itself. Some possible stunts are when the driver opens both doors and climbs out one side across the roof and in the other. This is very dangerous as the only hand holds are either side of the roof (which is a fair distance to reach) and the sudden change in direction of the centripetal forces could catch out an unprepared driver and throw them off the car. Others include getting out and walking round with the car as this video shows, however it also shows one of the dangers by a lapse in concentration as he waves to the crowd but stops walking and unfortunately is run over.
Doughnut TyresFor someone who has had enough of just white smoke, special doughnut tyres can be purchased. These tyres are similar to road tyres except they have had coloured pigment added to the rubber during the manufacturing process. These tyres are then fitted with similar or different colours and when the doughnut is done the white smoke is now a coloured one. During a top gear show the stig demonstated a red and blue tyre combination with impressive results producing large amounts of strongly coloured smoke. While these tyres are good for doughnuts they shouldn't be used on the road as they have decreased handling, grip and longevity unlike a standard road tyre.
Modern Racer - Driving Tips - Doughnuts