I wanted to put 18" rims on my max in the near future. I was wondering how difficult it would be to adjust my speedometer so that it would be accurate.

 

not difficult at all if you do it right and get the correct size diameter of tire for the wheel so that it matches the diameter of the factory tire.

Just because you go to a larger wheel doesnt mean that you get the wrong size tire diameter.

and yes the tires on the Maxima are a big enough diameter that when you put on 18s you will still have some sidewall with the correct diameter tire...they will not be rubber bands...not a whole lot of sidewall but more than it would be with a smaller car.