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Wheel PCD and Offset Explained

11 April 2012 One Comment

We have been getting quite the number of inquiry over the past year about rim fitment, so we thought we could help you guys better understand wheel PCD’s and Offset.

This is very important to know if you are planning on purchasing aftermarket rims. The offset is the distance in mm between the centre line of the wheel rim, and the line through the fixing (hub) face. You can have positive, negative or neutral offset. The first important reason offset is so important is that it is responsible for the position of the wheel under the wheel arch. Getting this wrong can cause your wheels to rub/scrape against the bodywork, suspension or not even move! Secondly it determines how the suspension and self centering steering are setup. The most common problem that will occur if you get it wrong is that the steering will either become super heavy that you can’t turn the steering wheel, or so light that you need to keep making corrections to stay in a straight line.

The term PCD stands for (pitch circle diameter) and is the diameter of a circle drawn through the centre of your rims bolt holes. PCD is measured in millimetres and also indicates the number of studs or bolts the wheel will have.
One of the most common fitments has 4 studs and a PCD of 100mm, hence the fitment 4×100.
PCD is not set to a curtain make or model of car, most cars share the same PCD, for example the Golf Mk1 has a 4x100PCD and so do the Opel Corsa B’s and the Toyota Corolla’s. The P.C.D. can be defined as the diameter (in millimetres) of an imaginary circle drawn through the centre of the stud holes on the wheel and/or the vehicle wheel hub.

When you decide to buy new rims, it is essential that they have the correct PCD For the vehicle concerned. Just because a wheel from one vehicle has the same PCD and offset as the wheel from another does not mean they are interchangeable – the centre bore of the wheel and hub must also be the same to ensure centralisation of the wheel, and the shape of the spokes must ensure clearance of the brake callipers. Many manufacturers use the same wheel fitments as others, but some are unique. So be very carefull when buying rims second hand from places like Gumtree and Junkmail.. Make sure you ask al the right questions.

One Comment »

  • Joe Klein said:

    Nice one Blair,this is always a problem when modfathers and sisters buy wheels. I’m one of those guys that struggle to get a nice wheel for my ride, I have the pcd 114.


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