18's look good but tires cost more when it comes time to replace-em, and you will running a lower profile tire so the ride quality will suffer a little and there will be a little better chance of damaging the wheel if you hit a nice size pot hole. If you dont mind the extra cost of 18's then the gain is well worth the loss. Im running 17's and no complaints. As for needing anything else in order to run the bigger wheels, you dont need anything.