hi, I've just Fit 18" R90 Replicas to my one and lowered it on eibachs. Its a good combination, the wheels fill the arches nicely and as of yet i havent noticed any rubbing, Just dont expect too much ride comfort, the combination of the low profile tyres and the firmer springs do mean that you feel the bumps a lot more. I got my springs from the classifieds section and fit them myself. Only cost me £70
I had eibachs on my MINI with 18's for about 6 months and it was fine, never any rubbing on the wheels and I thought the ride imrpoved a bit, harder but it was a bit better. dropped about 30mm
I have now taken those off and replaced them with KW1 coilovers lowered about 40-50mm and the arches are a few mm away from the tyre and still no scrubbing. Not quite sure how much more it dropped by but it is roughly 20mm more.
Get it done, you wont regret it!
EDIT: If it helps, my wheels are 18x7.5 with 215/35/18 tyres with et45