As mentioned my wheels are wider as well. But as you see 16mm front and rear are no problem, even with lower suspension. With original suspension maybe even a bit more is possible and everything less isn't a problem anyway. So it's all about how much wider you want it!
Basically every spacer fits designed for 5x108 bolt pattern and 60.1mm centre bore. The bolts are M12x1.5mm if I'm not completely wrong and make sure you don't take radius seated ones. As for the length I can measure them tomorrow because I have some of them lying around as I went for studs possibly even in the right length for you. It was a bit tricky for me as we are required to have a minimum number of thread revolutions which leaves only a small tolerance between too short and too long (which will scratch somewhere inside the hub). I ended up buying too long bolts and shortening them by myself.
Here another a bit older picture with 16mm front and 5mm rear. as you see with original tyre dimensions there is still plenty of space left which I could use for lowering.