jcb:
how much spacer required to take it to the arch edge will depend on the width and offset of the rim...
You should be aiming to keep the wheels offset as close as possible to the original design to reduce the adverse handling changes that occur from lowering it, i certainly wouldnt want to run any wheels lower than an ET35 combined offset (ie spacers and wheel offset together) as you will affect the handling, tyre wear and bearing life even at that level, and the more you move it, the more pronounced the negatives will be.
Unfortunately on a B5 the room on the inside is tight, so its often a requirement to lower the offset to get larger rims on the car. But at the same time i feel that people dont pay enough attention to keeping the geometry as close to stock as it should be, ie by buying 8.5" rims when 8" versions are available in the same design and suchlike.
If 8mm gives him enough room, then he shoudl be sticking with the 8mm's not going up to 10's
