Standard Wheel SizesST165
The stock wheel is a 15" diameter by 7" width (7J15). Standard tyres are 205/60/15.
The stock wheel is a 16" diameter by 7.5" width (7.5J16). Standard tyres are 215/50/16.
What is the offset required when ordering aftermarket wheels?
Most replacement allow wheel manufacturers use an adapter (spigot ring) to vary the diameter of the locating hole. The wheel itself has a large diameter hole which is "sleeved" down to the appropriate size with the spigot ring
In this way, a particular wheel can be used on a variety of vehicles by changing the spigot ring
The adapter/spigot ring arrangement is shown below
The 205 generally will not require such extremes but again depending on wheel choice and offset some spacers may be required One thing to note on the ST205. With the standard wheel (ET45) brake calliper clearance on the backside of the wheel is a serious issue. There is perhaps 2mm of clearance. The wheels also look well pushed in to the centre of the car.
An offset of 30 on a 7.5" rim will put the wheel almost exactly flush with the top of the wheel arch
This is one of the factors governing minimum offset on the ST205 setup
The use of spacers will put additional strain on wheel bearings. While modern bearings are much better at dealing with this than the older versions you should still be aware that you are potentially reducing their life span