I was wondering what size is best for some new rims for my 05 mini cooper. I was thinking of the konig hotswap mirrors. I was wondering if i would have rubbing problems with 18's or even 17's.

 

For the 2005 Base Cooper you have lots of options.

17x7 or up to 17x8 rims can be used. usually 205/45-17 or up to 215/45-17 can be used with stock suspension. If you lower your MINI you will have less clearance and the wheels will need to be of the correct wheel offset to avoid rubbing. Usually about +45mm offset is safe.

18x7 to about 18x7.5 is fine as well. 215/35-18 is a good size or 205/40-18 is possible. Just make sure the tire diameter is not much more than 24.7" tall for best clearance. Offset again about +42 to +45mm.

Realize that larger rims are usually heavier and the base cooper is not big on power. If you drive at normal street speeds then you will be fine. Also larger rims means smaller sidewalls that are stiffer and more prone to rougher handling on bad roads and possible risk of damage to the wheels or tires if you hit a pothole going fast.

The other problem with larger wheels is that the stock MINI brakes will look kinda small when matched with large wheels. For balance a big brake kit looks better although the stock MINI brakes are perfectly functional.