As long as you dont care for ride quality you can do 20's. lol. First i ran same as OE overall diameter. 225/35zr18. Didnt like the ride with the short tires. I run 215/45zr18 now and love it. Its almost 5% taller than stock and it does rub a little at full lock. But I wouldn't go smaller. When i go coilover i anticiapte more rub, but ill see