The ET value of a rim indicates its convexity. This is how far the rim is inside or outside the wheel arches. The ET value is also better known as offset value.
The number of bolt holes shows the number of bolt holes with which the rim can be fixed.
Rims are usually made of aluminium or steel.
- Steel rims are usually sturdier and can better withstand the salt that is spread in the winter. Steel rims are heavier, however, which means that less cargo can be transported.
- Aluminium wheels do not rust and retain their shine longer. Well-lubricated rims such as Alcoa's are generally stronger than steel rims. In addition, aluminium rims are lighter, which means that more cargo can be transported.