I have a 2004 FXSTSI, can I switch from a 16" rear wheel to an 18" without any mods? Will a lower profle rear tire make up for the 2" rim difference and if so what size tire do I need? I have not lowered the bike yet, but would like to drop it an inch or so. Will this affect the ability to change rear wheel size? I know...Alot of questions, but would appreciate a better understanding of this.