Slaney,
When someone changes the size of the wheels on a car the tires must me replaced also.
If you have 16" wheels, the tires are the standard "profile" (width of the sidewall), the circumference of the tire is critical.
If you change the size of the wheel to a 17", you need to get tires with a "lower profile" to maintain the correct circumference.
This means that the area between the tire and the wheelwell will remain the same as it is now.
Go to the following website and put in your year and model and when the cruiser comes up click on the tires under ASA JS5, it has three sizes and you will see what I tried to explain.
http://www.tirerack.com/index.jsp