You can also enter the car details in this website and it will give you the tires that will work on your car (based also on the engine size within the model). The numbers that are in bold
are the ones that are official for that vehicle. http://www.wheel-size.com/
As mentioned, the details can also be found in the owner's manual.
One other aspect of this website that can be very useful is that they give you the details on the rim
(width, diameter, offset, bolt pattern/diameter) in the event that you are buying used rims. You can ask the person to lift the numbers off the rim they are selling (most often stamped on the inside) to ensure you get a rim that works for your vehicle.