Is there anything I need to consider when upgrading from factory 17 inch rims 215 65 17 on my 06 Charger SXT to 06 RT rims 225 60 18's? Will this effect my speedo or ride quality?

 

It depends on the outside height of the tire. Based on the specs the profile should be close in over all height, so answering your question, you should be fine. Many LX, LY owners swap out for RT wheels, or SRT OEM wheels. I've done it on my Charger, those are off a Maggie SRT, which ended up being the same height as my RT stock wheels, just smaller profile.