i used to ride hella low on 15's, slammmed. had about 10mm-15mm clearance at max under the frame rails.
http://img686.imageshack.us/img686/5945/m30.jpg
http://img410.imageshack.us/img410/5...ef03a8ac32.jpg
so after destroying tires like crazy with crazy camber and scraping everything. i decided to go 18's.
http://img692.imageshack.us/img692/2007/s5000167.jpg