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Selecting the Correct Wheel Spacer Size

When it comes to fitting wheel spacers there are a number of things that need to be considered before making a purchase. We'll take a look at them step-by-step so that you can be confident of fitting the correct spacer kit to your car.

1. Wheel Bolts or Nuts

Are your wheels held in place with wheel bolts or do the hubs have threaded studs and the wheels are fixed with wheel nuts? While most most manufacturers use wheel bolts a few still use wheel nuts - some manufacturer models can even have bolts on one car and nuts on another (for cars manufactured in the same year!).

2. Number of Bolts/Nuts per Wheel

Another easy one that requires only a visual check. How many bolts or nuts are used to hold each wheel in place? Typically this will be 4 or 5 but there are a few cars that only use 3 bolts and some 4x4's that have 6 studs/bolts per wheel.

Obviously the number of bolts/nuts used per wheel will have to correspond to the number of holes on the spacers that you purchase

3. Bolt or Stud Diameter & Thread Pitch

Although it's not usually an issue, some manufacturers changed the bolt diameter on newer models while keeping all other specifications identical e.g. BMW and Mercedes. If you're unsure of the exact model type then it's a good idea to check the bolt diameter and thread pitch before ordering.

Bolt Diameter - this is measured in millimeters and is referred to as "M" in the bolt size world i.e an M14 bolt will have a 14mm diameter shaftBolt shaft diameter


Thread Pitch - this is calculated by measuring the distance in millimeters between 10 threads. This number is then divided by 10 e.g if the distance of X in the image below equals 15mm then the thread pitch will be 1.5mm (i.e. 15 ÷ 10). Almost all wheel bolts will have a thread pitch of either 1.25mm or 1.5mm.Bolt thread and pitch


4. Bolt Pattern / PCD

Pitch Circle Diameter, more commonly known by the abbreviation PCD, is the measurement of the diameter of an imaginary circle drawn through all of the wheel bolts or studs on a wheel.

4-Stud Hubs - Measuring the PCD of 4 or 6-stud wheel hubs is straightforward, just measure the distance from the outside of one bolt hole to the inside of the opposite hole as shown in the image below.Measuing PCD 4-stud


5-Stud Hubs - This is a bit trickier, but still not difficult. Measure the distance from the outside of any bolt hole to the inside of the adjacent hole as shown in the image below - now multiply that figure by 1.7012 e.g if the measurement of 'X' is 65.8mm then the PCD will be 112mm (65.8 x 1.7012 - rounded to the nearest decimal point)How to measure PCD

Thus, a wheel spacer advertised as 5x112 PCD will fit cars that use 5 wheel bolts per hub and that have a pitch circle diameter of 112mm

5. Centre Bore Diameter / Hub Lip

Centre bore diameter / Hub lipThe centre bore measurement is the diameter of the hole in the centre of the wheel that fits over the hub lip (spigot) and is measured in millimeters. This measurement (marked 'A' in the image below) must correspond to the centre bore diameter measurement of the spacers that you want to fit. If the spacer's center bore is smaller then the spacer will not fit on the wheel hub.

Just as important is measurement 'B' - the hub lip must NOT protrude further than the machined recess in the spacer which is approximately 2mm less than the spacer thickness i.e 15mm spacers will have a 13mm recess, 20mm spacers will have an 18mm recess etc.

As an example if you purchase 15mm spacers then measurement 'B' must be less than 13mm otherwise the spacer will not be able to sit flush against the wheel hub face. If this happens then the hub lip on the spacer will almost certainly crack when the spacer/wheel bolts are tightened.


6. Spacer Thickness

Measure the gap between wheel arch and tyre wallIt is just as important to make sure that there is sufficient space between the wheel arch and the tyre wall to accommodate the spacer.

Measure the distance between the top, outer edge of the tyre to the inner edge of the wing/fender. We recommend that you leave a gap of 5 to 10mm between the tyre and the body to avoid damage to the tyre as the suspension moves. e.g gap = 30mm / Spacer required = maximum 25mm / preferred 20mm.