The turning radius or turning circle of a vehicle is the size of the smallest circular turn (ie. U-turn) that the vehicle is capable of making. NOTE that the term turning radius is actually a misnomer. The size of a circle is actually its diameter, not its radius. The less ambiguous term turning circle is preferred. As an example, Motor Trend refers to a curb-to-curb turning circle of a 2008 Cadillac CTS as 35.5 feet. By contrast, theAutoChannel.com refers to turning radius of the same car as 35.5 feet. It is often used as a generalized term rather than a numerical figure. For example, a vehicle with a very small turning radius may be described as having a "tight turning radius".

Two different measurements can be quoted for a vehicle. A curb or curb-to-curb turning circle will show the distance traveled by the wheels. The wall or wall-to-wall turning circle will include an allowance for the width of the whole car, including the overhang of the bodywork. For example, a van may have be quoted as having a turning circle (in meters) of 12.1(C)/12.4(W).

It may be easier to imagine that on a road with low curbs, you don't need to consider anything other than the tires (12.1 meters), that is the curb turning radius, but if you were moving the vehicle inside a building, the corners of the vehicle might hit the walls so you need to consider the wall-to-wall turning radius (12.4 metres).

A notable exception in this description is of vehicles that are capable of spinning around their central axis, such as a tank or certain lawnmowers as they do not form a circular path as they turn. In this case the vehicle is referred to as a "zero turning radius" vehicle, although whether or not the turning radius is actually nonexistent is unclear.

Some camera dollys used in the film industry have a "round" mode which allows them to spin around their z axis by allowing synchronized inverse rotation of their front and rear wheel sets, effectively giving them "zero" turning radius.

Turning circle is sometimes measured as the diameter of the minimum turn rather than the radius.

[edit] Common uses

• Wheeled vehicles
• Aeroplanes
• Watercraft

[edit] See also

• U-turn (maneuver)

[edit] External links

• Link to Wisegeek article about turning radius
• Grounds Maintenance Magazine Article about Zero Radius Lawn Mowers
• JL Fisher Model 10 Dolly Specifications