The
turning radius or
turning circle of a
vehicleA vehicle is a mechanical means of conveyance, a carriage or transport. Most often they are manufactured , although some other means of transport which are not made by humans also may be called vehicles; examples include icebergs and floating tree trunks.Vehicles may be propelled or pulled by...
is the size of the smallest
circularA circle is a simple shape of Euclidean geometry consisting of those points in a plane which are equidistant from a given point called the centre. The common distance of the points of a circle from its center is called its radius....
turn (ie.
U-turnA U-turn in driving refers to performing a 180 degree rotation to reverse the direction of travel. It is called a "U-turn" because the maneuver looks like the letter U. In some areas, the maneuver is illegal, while in others it is treated as a more ordinary turn, merely extended...
) 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
diameterIn geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
, not its
radiusIn classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter....
. 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.
The
turning radius or
turning circle of a
vehicleA vehicle is a mechanical means of conveyance, a carriage or transport. Most often they are manufactured , although some other means of transport which are not made by humans also may be called vehicles; examples include icebergs and floating tree trunks.Vehicles may be propelled or pulled by...
is the size of the smallest
circularA circle is a simple shape of Euclidean geometry consisting of those points in a plane which are equidistant from a given point called the centre. The common distance of the points of a circle from its center is called its radius....
turn (ie.
U-turnA U-turn in driving refers to performing a 180 degree rotation to reverse the direction of travel. It is called a "U-turn" because the maneuver looks like the letter U. In some areas, the maneuver is illegal, while in others it is treated as a more ordinary turn, merely extended...
) 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
diameterIn geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
, not its
radiusIn classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter....
. 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
generalizedA generalization of a concept is an extension of the concept to less-specific criteria. It is a foundational element of logic and human reasoning. Generalization posits the existence of a domain or set of elements, as well as one or more common characteristics shared by those elements. As such, it...
term rather than a
numerical figureA number is a mathematical object used in counting and measuring. A notational symbol which represents a number is called a numeral, but in common usage the word number is used for both the abstract object and the symbol, as well as for the word for the number...
. 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
curbCurb may refer to:* Curb , or kerb, the edge where a raised pavement/sidewalk/footpath, road median, or road shoulder meets an unraised street or other roadway.* Curb Records, a record label started by Mike Curb in 1973....
s, you don't need to consider anything other than the
tiresA tire is a ring-shaped covering that fits around a wheel to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
(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
spinningA rotation is a movement of an object in a circular motion. A two-dimensional object rotates around a center of rotation. A three-dimensional object rotates around a line called an axis. If the axis of rotation is within the body, the body is said to rotate upon itself, or spin—which implies...
around their central axis, such as a
tankA tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility and tactical offensive and defensive capabilities...
or certain lawnmowers as they do not form a circular path as they turn. In this case the vehicle is referred to as a "
zero0 is both a number and the numerical digit used to represent that number in numerals. It plays a central role in mathematics as the additive identity of the integers, real numbers, and many other algebraic structures. As a digit, zero is used as a placeholder in place value systems...
turning radius" vehicle, although whether or not the turning radius is actually nonexistent is unclear.
Some
camera dollyA camera dolly is a specialized piece of film equipment designed to create smooth camera movements. The camera is mounted to the dolly and the camera operator and camera assistant usually ride on it to operate the camera...
s used in the
film industryThe film industry consists of the technological and commercial institutions of filmmaking: i.e. film production companies, film studios, cinematography, film production, screenwriting, pre-production, post production, film festivals, distribution; and actors, film directors and other film...
have a "round" mode which allows them to spin around their z axis by allowing
synchronizedSynchronization or synchronisation is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time....
inverse rotation of their front and rear wheel sets, effectively giving them "zero" turning radius.
Turning
circle is sometimes
measuredIn science, measurement is the process of obtaining the magnitude of a quantity, such as length or mass, relative to a unit of measurement, such as a meter or a kilogram...
as the
diameterIn geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
of the minimum turn rather than the radius.
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