Term

Definition

Motor vehicle length

The distance between two vertical planes perpendicular to the longitudinal median plane (of the vehicle)
and touching the front and rear of the vehicle respectively.

 NOTE — All parts of the vehicle, including any parts projecting from front or rear (towing-hooks, bumpers,
etc.) are contained between these two planes.

Vehicle height (unladen)

The distance between the supporting surface and a horizontal plane touching the topmost part of a vehicle.

 NOTES
1- All fixed parts of the vehicle are contained between these two planes.
2 -The vehicle is in operating order and unladen.

Vehicle width

The distance between two planes parallel to the longitudinal median plane (of the vehicle) and touching
the vehicle on either side of the said plane.

NOTE — All parts of the vehicle, including any lateral projections of fixed parts (wheel hubs, door
handles, bumpers, etc.) are contained between these two planes, except the rear-view mirrors, side
marker lamps, tire pressure indicators, direction indicator lamps, position lights, customs seals, flexible
mud- guards, retractable steps, snow chains and the deflected part of the tire walls immediately above
the point of contact with the ground.

Motor vehicle or trailer wheel
space

The distance between the perpendicular lines constructed to the longitudinal median plane (of the
vehicle) corresponding to two consecutive wheels situated on the same side of the vehicle.   

 NOTES
1- If the values of right and left wheel spaces are different, both dimensions are stated, separated by a
dash, the first corresponding to the left wheels.
2- For vehicles with three or more axles, the wheel spaces between consecutive wheels are indicated,
going from the foremost to the rearmost wheel: the total wheel space for right or for left is the sum of
these distances.

Semi-trailer wheel space

The distance from the axis of the fifth wheel kingpin in a vertical position to the vertical plane through
the axis of the semi-trailer’s first axle,

 NOTE — In the case of a semi-trailer with two or more axles, the same rule should be applied as for
vehicles with three or more axles.

Track

In the case of two single wheels corresponding to the same real or imaginary axle, the track is
represented by the distance between the axes of the traces left by the wheels on the supporting surface.
In case of dual wheel, the track is represented by the distance between the middle of traces left by the
dual wheels on the supporting surface.

Ground clearance

The distance between the ground and the lowest point of the centre part of the vehicle. The centre part is
that part contained between two planes parallel to and equidistant from the longitudinal median plane
(of the vehicle) and separated by a distance which is 80% of the least distance between points on the
inner edges of the wheels on any one axle.

Vertical clearance

The vertical displacement of a wheel in relation to the suspended part of the vehicle from the position corresponding to the maximum permissible load to the position from which any additional vertical travel is impossible.

Front overhang

The distance between the vertical plane passing through the centers of the front wheels and the foremost point
of the vehicle, taking into consideration lashing hooks, registration number plate, etc., and any parts rigidly
attached to the vehicle.

Rear overhang

The distance between the vertical plane passing through the centers of the rearmost wheels and the
rearmost point of the vehicle, taking into consideration the towing attachment, registration number plate,
etc., and any parts rigidly attached to the vehicle.

Ramp angle

The minimum acute angle between two planes, perpendicular to the longitudinal median plane of the
vehicle, tangential, respectively, to the tires of the front and the rear wheels, static loaded, and
intersecting at a line touching the lower part of the vehicle, outside these wheels. This angle defines the largest
ramp over which the vehicle can move.

Approach angle

The greatest angle between the horizontal plane and planes tangential to the static loaded front wheel
tires, such that no point of the vehicle ahead of the axle lies below these planes and that no part rigidly attached
to the vehicle lies below these planes.

Departure angle

The greatest angle between the horizontal plane and planes tangential to the static loaded rear wheel
tires, such that no point of the vehicle behind the axle lies below these planes and that no part rigidly
attached to the vehicle lies below these planes.

Lift

The height to which a wheel may be lifted without any other wheels leaving their supporting surface.

Turning clearance circles

The turning clearance circles (the steering wheel being turned to full lock) are
1) The diameter of the smallest circle enclosing the projections onto the supporting plane of all points of the
vehicle.
2) The diameter of the largest circle beyond which are located the projections onto the supporting plane of all
the points of the vehicle.

 NOTE — Each vehicle has right-hand and left-hand turning clearance circles.

Turning circles

The diameters of the circles circumscribing the extensions on the supporting plane of the mid planes of
the steered wheels (the steering wheel being turned to full lock).

 NOTES
1 - The smaller diameter of the circle circumscribing the extension on the supporting plate of the
mid-plane of an inner non steered wheel is also of practical interest.
2-  Each vehicle has left-hand and right-hand turning circles.

Castor

The distance between two points p and q this distance is the projection onto a plane parallel to the longitudinal
median plane (of the vehicle) of the acute angle formed by the vertical and the real or imaginary swiveling axis
of the stub axle.

It is positive when p is ahead of q in the direction of normal travel.

Kingpin inclination

The projection onto a plane perpendicular to the longitudinal median plane (of the vehicle) of the acute
angle, formed by the vertical and the real or imaginary swiveling axis of the stub axle.

Kingpin offset

The distance from the extension of the swiveling axis of the stub axle onto the supporting surface to the
extension onto the same plane of the mid-plane of the wheel.

The kingpin offset shown on the drawing is positive.

Toe-in (length)

The length defined as follows:
The ends of the horizontal diameters of the interior contours of the rims corresponding to the same axle
are the apices of an isosceles trapezium. The difference between the length of the rear base and that of
the forward base of the trapezium is the toe-in, the difference being positive when the wheels are closer
together in front than behind, and negative in the contrary case.

Toe-in (angle)

The angle formed by the horizontal diameter of the wheel and the longitudinal median plane (of the
vehicle) or the acute angle formed by the vertical plane G passing through the axis of the axle-pin
and a vertical plane H perpendicular to the longitudinal median plane (of the vehicle).

Camber angle

The acute angle between the axis of the axle-pin and a horizontal line in the vertical plane through
that axis. The angle is positive when the point of the V formed by straight lines supporting the wheel
axles is directed downwards.

NOTE
This angle is equal to the acute angle formed by a vertical line and the mid-plane of the wheel.
These two angles, considered in the same plane, have their sides perpendicular to each other.