I was looking at the ecs tuning site this morning because I was thinking of ordering wheel spacers and I saw a conversion kit that says it's 20mm to go from 5x100 to 5x120 so I can use BMW wheels (which is what I want). Does this act as the conversion and also a wheel spacer? Will 20mm be too much? I wanted 20mm in the rear and 6 in the front but I really like the 2006 BMW 3 Series E90 Wheels. Will I have any problems rubbing?