Alloy Wheels
For most alloy wheels customers the wheel style is quite rightly the most important consideration when purchasing a set of alloy wheels for their car. Of course as well as looking good the wheel and tyre combination is also one of the most significant safety items on the car and the correct wheel and tyre package must be fitted. In this technical section we have tried to keep it simple as most people are looking for correct information rather than a science lecture. So here we go, try to keep up I’ll be asking questions at the end.
A typical alloy wheel could have the following dimensions 7x17 4/100 ET40 60mm
7 is the rim width, measured across the inside of the wheel well
17 is the rim diameter, the measurment inside the lip of the wheel
4 or 4 stud is the number of nut holes or bolt holes. Most modern cars use 4 or 5 stud wheels. Some 4x4 alloy wheels are fixed using 5 or 6 stud alloy wheels. One exception is older Citroen and Peugeot models which used a 3 stud alloy wheel. The smart car range has also utilised 3 stud fixing alloy wheels.
 
100 is the PCD or pitch circle diameter
The PCD is simpley an imaginary circular line that passes through the centre of the nut or bolt hole on the alloy wheel. It is critical that the correct PCD for each model is used, failure to do this can result is the wheels working loose and leaving the vehicle. For 4 stud alloy wheels it is quite simple to find the PCD by measuring across the stud holes. 3 stud, 5 stud and 6 stud alloy wheels are a little more difficult as you have to draw a line through the centre of each stud hole to determine the PCD.
ET40 is the offset, this determines in simple terms how far the wheel sticks in or out on the car. It sounds simple enough but to get the most from your cars handling the correct offset must be used. Incorrect offset can lead to uneven tyre wear, tramlining and wheel and tyre packges catching the bodywork and causing damage to both the tyres and the wheel arches. To measure the offset of an alloy wheel we need to imagine a centre line to the bolt up face. The bolt up face is the flat part that bolts to the car. With the wheel upside down place a flat edge across the wheel then measure from your flat edge to the bolt up face, so for example the measurment is 120mm. Now measure the wheels width so for example 160mm. Subtract the first figure from the rim width to give you a figure of 40mm. Because this figure is a positive number ie not a minus number we say the offset is positive so we have a positive 40mm offset. If our first figure we measured to the bolt up facewas 170mm we would again subtract this from the rim width 160mm to give a figure of -10mm because this number is negative we say the offset is negative. Negative offset wheels are usually found on 4x4 alloy wheels and older cars wheels and typically have a deep dish look from the front.
 
60mm is the centre bore, this is the centre hole of the wheel under the centre cap and is where the alloy wheel sits onto the cars wheel hub. Along with the wheel bolts or wheel nuts the wheel hub locates the wheel centrally onto the car. Central wheel location is important for wheel balance. Most wheel manufacturers of after market alloy wheels use a system of plastic spigot rings to locate the wheel on the car. This allows them to use one wheel casting to suit many cars. For example a Rover, a Mazda and a VW may share the same offset and PCD wheels but have different centre bores, 54mm for the Mazda, 56mm for the Rover and 57 for the VW. By manufacturing their wheels with a large hole to accept a spigot ring with an outer diameter of 73mm they can use spigot rings 73mm outside diameter and 57.1mm internal diameter for the VW, 73mm outside diameter and 56.1mm internal diameter for the Rover and so on. The .1mm clearance is needed so the ring is a shuffle fit onto the hub if it was exactly the same size it would not go over the hub.
We supply many of the worlds best know alloy wheel brands including AEZ alloy wheels, Dotz alloy wheels and League alloy wheels. The range we supply includes Car alloy wheels, Van alloy wheels and 4x4 alloy wheels. If you want to replicate an original equipment style we offer our Replica alloy wheels for the likes of Audi and VW. For those on a modest budget or just looking for excellent value for money we have cheap alloy wheels to suit most customers. For older Peugeot 106 and Citroen Saxo models with 3 stud hubs we can offer a range of 3 stud alloy wheels.
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