Where do you live? I have some 18's with tyres on if you're close to Woking/Surrey area, I think I've got 6, just return them without tyres on at all. I've done 16's before, I used 40mm spacers to be safe to clear the calliper but that was due to the lip inside the alloy. I used standard 200sx alloys. I also have 8 16" alloys, some without tyres on if you need some, I'd sell them to you for cheap. I could post you some up if you organise shipping too. Ride height was fine and it smoked them up nicely.