1 tire line. 42x13.50R20 tires sized to your wheels and your car.
42x13.50R20 is a flotation size: 42 inches tall, 13.50 inches wide, on a 20 inch wheel. In metric it is 343/81R20, which is how the catalogue stores it. Whether 42x13.50R20 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 42x13.50R20, from Nitto. 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 42x13.50R20 lines that do both.