Help! What width wheels fit the mk3 without adjusting arches etc

[Ryan1991cupra]

im looking to purchase a brand new set of 17” alloys for my modified mk3 Ibiza, I’m trying to get as much rubber on the road as possible as I have a lot of power going to the front wheels just hoping somebody can tell me what’s the widest wheel I can fit straight on it without having to alter the arches or suspension etc etc, car is currently lowered 30mm all round, and I have a selection of spacers if needed for new wheels. Any help would be greatly appreciated Ryan