Wheels, Offset, and How to Calculate Fitment

Check for clearance difficulties when installing aftermarket or custom wheels before proceeding with the installation.

Incorrect fitment or rubbing will cause your tires and bearings to wear out early, as well as other suspension components to fail or wear sooner than they should.

Offset is the distance in millimeters between the centerline of the wheel and the mounting face of the wheel.
When it comes to wheel styles that are flush or convex, offsets are more often than not positive (+).
Concave style and the use of spacers are common characteristics of negative (-) offsets.

The Offset, or "ET" (Einpress Tiefe translates to Press Depth in German),
determines the distance between the center of the rim surface and
the face of the wheel where it is bolted to the hub.

Positive Offset

It is possible to have a positive offset when the hub mounting surface is located on the street side (the side that you can see) of the rim's center line. This type of offset will be seen on the majority of factory rims.

Negative Offset

If the hub mounting surface is on the brake side of the centerline of the rim, it is considered a negative offset or "deep dish".

WARNING: Incorrect offset can seriously affect vehicle performance.

Rim Measurement Diagram - Mini Mania Inc. Positive Offset Diagram - Mini Mania Inc. Negative Offset Diagram - Mini Mania Inc.
Rim Measurements Positive Offset Negative Offset

Example:

This stock 4.5" x 10" Mini Cooper S alloy wheel has a POSITIVE Offset of 35mm.
It would be seen as 4.5" x 10" wheel, 4 x 4" lug pattern, Offset of ET35.Offset explained - Mini Mania Inc.

This Minilite 6" x 10" Mini Cooper S wheel has a POSITIVE Offset of 15mm.
It would be seen as 6" x 10" wheel, 4 x 4" lug pattern, Offset of ET15.
Offset explained - Mini Mania Inc.

This Super Trax 7" x 13" Mini Cooper S wheel has a POSITIVE Offset of 7mm.
It would be seen as 7" x 13" wheel, 4 x 4" lug pattern, Offset of ET07.
Offset explained - Mini Mania Inc.

This Alleycat 7" x 13" Mini Cooper S wheel has a NEGATIVE Offset of 7mm.
It would be seen as 7" x 13" wheel, 4 x 4" lug pattern, Offset of ET-7.
Offset explained - Mini Mania Inc.

 

a wheel with NEGATIVE (-) 15mm OFFSET or ET would be shown as ET-15
a wheel with POSITIVE (+) 7mm OFFSET or ET would be shown as ET07




Basic rule of thumb:
- Higher offset (ET50 for example), wheels sit closer to the car, have a chance of hitting brake and suspension components
- Lower offset (ET10 for example), wheels sit further out from the car, lots of room for components but may poke past fender or impact fender on dips and bumps

 

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