i have no idea what your factory offset is on a new Clio but in case youre wondering what is the background to all these numbers, in basic terms:
Offset is the distance between the imaginary centre line of the wheel and the hub mounting face. Almost all road cars run negative offset which means that instead of the mounting face being right in the centre (i.e. outer and inner rim edge are an equal distance away), it is closer to the outer edge. Neg offset is so common that people dont even bother mentioning minus numbers any more. The further the hub mounting face is away from the centre-line ( and thus, the close to the outer edge), the more offset you have.
This has a rather confusing effect, in that the more offset a wheel has, the less it sticks out from the car. Therefore if your Clio has say a 42 offset as standard if you put a wider wheel/tyre on with the same 42 offset, you will find the extra width is shared equally between the outer and the inner edge. So if you go an inch bigger on the wheel width, keeping the same offset results in an extra half inch of wheel inside and outside.
The problem occurs when your car is lowered as well, because it may be more beneficial to move the entire wheel inwards or outwards to avoid fouling the suspension or the outer wheelarches. Usually moving inwards is better because there should be some room before you start touching the suspension strut, but there is often very little on the wheelarch side.
So by lessening your offset, say changing from a 42 to a 32 offset you effectively push the wheel 10mm outwards. By increasing the offset the other way, to say 52mm you will bring the wheels inwards by 10mm. Offsets over 50mm are difficult to obtain in normal wheels. This is why Vauxhalls which ran high factory offsets always had problems getting aftermarket alloys to not stick out miles.
If you really want to go to town, you need to look inside your wheelarch and decide whether once youve got the extra width of your new wheel on, do you want the wheel to stay centred where it is, move it inwards or move it outwards, bearing in mind that if you lower it you will definitely run into trouble the wider you go without fiddling the offset.
