GMP ATOM SIL

Rim width

Width from rim to rim in inches (").

Markings on the rim: 9.0X21 5X112 / 45

9.0 - Rim width 9 inches (228.6 mm)

Diameter

Rim height in inches (").

NB!

When mounting rims larger than the original diameter of car, care must be taken to maintain the original height of the wheel (rim + tyre).
The ABS, ASC, DSC, etc. stability control systems of the car are designed to work correctly only with the correct wheel diameter.

Bolts

Number of rim fastening bolts.

PCD

Bolt pattern shows how many bolts or nuts attach the alloy rim to the wheel hub.

The bolt pattern and the pitch circle diameter (PCD) are interrelated – they are usually marked together. For example, 5×120, where 5 shows the number of bolts and 120 the PCD in millimetres.

Offset

Offset (ET) is indicated in millimetres.

The parameter shows the distance between the rim centre axle and the wheel hub mounting surface.

A different offset affects the displacement of the rim in the wheel arch. It is important to know that the position of the rim in the wheel arch is not only dependent on the offset but also on the overall width of the rim.

For example, the 18″ x 8J ET45 rim protrudes out from the wheel arch almost as much as the 18″ x 7J ET35 rim.

Centerbore

The centerbore (CB) aka alignment hole is the hole in the centre of the rim, by means of which the rim is mounted on the wheel hub.

The hub size varies depending on the car manufacturer.

To fit rims with larger centerbore to a vehicle with smaller hubs, centring rings included in the set are used.