I got my 718 C with the standard 18" wheels. I am thinking about getting 19" wheels, but to keep the ride civil, going with tires that are the same sidewall profile as the 18s. That will increase the circumference of the tires. I didn't see a setting anywhere where you could enter the tire's measurements. So, if I go with my plan, what would that do to the speedometer and odometer in the car? I tried to math it out myself, but quickly came to the conclusion that it is a good thing that I became a lawyer.