Im running 20mm spacers on a offset of E35, so that means an overall offset of 5.
This is about as much as I can go, as it is rubbing a little, and I will need to get the arches rolled.
Theres no chance of me even lowering it.
So I would say a offset of 10/15 should be fine, so you could properly run 10mm rear and 15 front.