Arith wrote:What's the offset? How wide will the wheels be? Is your car lowered? These will determine whether scrubbing/rubbing will occur. If your car is lowered, you'll need to at least roll the fenders in the front. If it's not lowered, it's going to look ridiculous running 20's.
My Prodrives have a 51 off set & they are 18 x 8's... Fit nicely & unless I lower it like crazy, no scrubbing etc.
If I was looking for 20's, I'd be looking at something that around 7.5 or 8 wide... Off set between 55 (Think that's the off set on the stock TBI STI rims) & 51... Combined with the correct tyre size (225/30 20?) you should not have any dramas.
Other thing to be aware of is how large you breaks are planning on running... The off set on my rims clears Brembo's nicely

... But then they have a rather large "X Factor" which is another important thing that not many consider.