This standard is compiled by reference to the International Standard “Motor vehicles and towed vehicles-Dimensions of vehicles-Terms and Definitions” (ISO 612-1978).
1 Subject Content and Application Scope
This Standard defines terms relating to dimensions of motor vehicles and towed vehicles. It does not deal with methods of measurement, the units used in reporting the results or the accuracy required or the order of magnitude of the dimensions defined.
This standard is applicable to the motor vehicle and trailer which is specified in the national standard "Motor vehicles and Semi-trailers-Types of Vehicles-Terms and Definitions"(GB 3730.1).
2 General Requirements
2.1 Horizontal supporting surface (Plane X)
It is a flat, firm horizontal plane and used to support the wheels when measuring the parameter of vehicle dimension.
2.2 Central plane of wheel
For single wheel, the central plane of wheel is the plane which is equidistant to the inside edge of both sides of wheel rim.
For double wheels, the central plane of wheel is the plane which is equidistant to distance from the inner edge of one wheel to the outer edge of the other.
2.3 Wheel center
It is the intersection point of central plane and rotation center line of wheel.
2.4 Longitudinal median plane of the vehicle (Abridged English: Plane Y):
The vertical plane Y passing through the mid-points of AB perpendicular to AB, A and B being defined as follows:
GB/T 3730.3-1992 The following standards are cited：
GB/T 3730.3-1992 Cited by the following standards：
