The bolt hole designs in rims are used to fasten the wheels to the vehicle hubs securely. They not only bear the weight of the vehicle and the load but also have to withstand the enormous forces during operation. Only a proper bolt hole design guarantees the safety of the vehicle.
Various bolt hole designs
There are different types of bolt hole designs, which can vary depending on the vehicle type and application. The three most common versions are:
- Cylindrical bolt holes: this version is characterised by a cylindrical passage. Cylindrical bolt holes typically have some play. The wheel is centred via the hub hole (hub centring).
- Spherical countersunk bolt holes: this version has a countersunk recess which serves to centre the bolts and ensure a secure connection.
- Spherical/conical countersunk bolt holes: this design combines a spherical and conical recess and enables even more precise centring of the bolts.
Bolt hole labelling and identification
The shape and size of the bolt head and the design of the bolt holes must be precisely matched. Bolt holes are identified and marked according to a standardised system defined by the Association of European Wheel Manufacturers (EUWA).
This system encodes information about
- the diameter of the bolt holes
- the shape of the countersink or recess (cone or sphere)
- in the case of a conical bore, the cone angle
- the dimensions of the recess
Correct labelling enables fitters to reliably identify the right bolts for the given hole design.
The arrangement of bolt holes
In commercial vehicles, the arrangement of the bolt holes can vary considerably to meet special requirements in terms of load capacity and stability. Each of these arrangements must correspond precisely to the specifications of the vehicle in order to ensure safe assembly and optimum functioning. Here are the most common arrangements and geometric patterns:
- 6-hole arrangement: the bolt holes are normally distributed evenly on a circle, for example in the format "6 x 205", which means that six bolt holes are arranged on a circle with a diameter of 205 mm.
- 8-hole arrangement: the bolt holes are usually distributed evenly on a circle, for example in the format "8 x 275", which describes eight bolts on a 275 mm circle.
- 10-hole arrangement: here too, the bolt holes are usually arranged evenly on a circle, for example in the format "10 x 335".