Also keep in mind that deviating from 255/40 R20 may change the overall diameter and introduce some speedometer and odometer errors. Check for yourself at
Tire Size Comparison and make sure you are okay with the error in speed if you deviate from the standard size.
Stock for MY is 28 inch diameter, so that is 255/45 R19 or 255/40 R20 or 255/35 R21