1 tire line. 225/45R21 tires sized to your wheels and your car.

225/45R21 means a 225 mm section width, a sidewall 45 percent of that (101 mm) and a 21 inch rim, which works out to 29 inches tall. Whether 225/45R21 works comes down to the wheel width it mounts on and how far it lands from the height the car left the factory with.
1 line carries 225/45R21, from Michelin. By type that is 1 all season. The tire has to stay near your car's stock height and mount on your wheel width, so pick the car and the wheel set and the page keeps only the 225/45R21 lines that do both.