What size rims an owner should put on a stock Ferrari depends on the year and model of the vehicle. If the Ferrari has been customized, or if the owner wants to deviate from recommended rims, the rim may also drastically affect performance.
On a 1994 Ferrari 348 GTB or GTS, for example, a rim that will work is one marked with 8x18 ET40, meaning the rim has a width of 8 inches, a diameter of 18 inches and a positive offset of 40 mm.
When choosing a rim that's outside recommended specifications, a car owner should consider aspects of the rim such as size and weight. Certain rims, depending on whether they're meant to work with a certain vehicle, may void the manufacturer's warranty of the car if installed.