The wheel disk forms the connection between the rim and the wheel hub. The disk is used to connect the wheel and rim to the vehicle. This can be done on the hub plate (flange) or the brake drum.
The shape of the disk is determined by several factors. For instance, the shape of the rim, the axle connection and the shape and type of brake. However, load-related requirements and aesthetic appeal are also considered.
Wheels can be mounted in various ways (depending on the vehicle). You must take a few things into account, mainly the size. Wheel manufacturers mention this information along with the vehicle specifications. What you must look out for:
- Diameter centre hole
- Diameter bolt circle
- Number of bolt holes
- Diameter of bolt holes
- Type of bolt holes
- Position of the wheel disk (ET value)
Offset or ET value
The offset (or ET value) is the distance between the centre of the rim and the mounting pad and hub. The offset (or ET value) can be either positive or negative. The track width of the vehicle is determined by the flange size/axle length and the offset of the rim.
The offset will be positive if the back of the mounting pad is located past the rim's centre line and closer to the face of the rim. The offset will be negative if the back of the mounting pad is behind the centre line of the rim.
In addition, it is very important to mount the right tyres on the right rims (recommended or permitted). Make sure width and construction are correct; i.e. single-part or multi-part.