- Fixed center bore: the wheel can be fitted only and exclusively on the cars which have the diameter of the hub for which the wheel was projected.
- Unified center bore with reducing spigot bushing: the wheel is built to fit on different cars by means of a special reducing spigot bush. Its correct fitting grants the same safety characteristics as a wheel with fix-sized center bore.
Hump (Rim ribbing)
Areas on the rim where the profile displays ribs necessary to prevent the unthreading of the tyre in case of puncture. The Hump profile is made according to the requirements of ETRTO (European Tyre and Rim Technical Organisation) and of JATMA (Japan Automobile Tyre Manufacturers Association).
Wheels with double PCD
Some wheels have two sets of fastening holes (PCD) in order to allow the installation of the same wheel on cars with different characteristics.
Ex: F1 Evo 7x15 PCD1 = 100 x 4
PCD2 = 108 x 4
Wheels with inverted rim
To improve aesthetics, some wheels are provided of a deep lip which requires a non-traditional way to mount the tyre; i.e. the tyre has to be mounted from the side opposite to the flange side. They are called wheels with "inverted rim".