Change Simple Weather from Default to "Scripted Weather" which will now allow you to change your Real Road to another choice if the track modder added additional presets. You can add more Real Road presets by allowing several AI run laps then saving and naming it such as Light, Medium, Heavy, or Saturated.
Note: When making your Real Road you can speed up the process using the "Real Road Time Scale" plus also using Ctrl+X will rapidly speed up AI laps!