this will all depend on, what mark golf, what offset your wheels are, what tyres you have etc etc there are no hard and fast rules to say what you need. look at the car and the clearance you have between arch and tyre. if you have 15mm space and want it on the arch, you'll need a 15mm spacer.... but just beware that you'll probably scrub like hell, unless you've done some clever arch tweaking/rolling/camber.
the cars you see with alot of wheel poking out normally have stretched tyres, alot of camber and probably took alot of effort to get it like that.
for example it took two of us, 3 hours to work out the right ride height, camber and 4 sets of various thickness spacers before getting this car to sit like this with no rubbing:


