Admittedly not one thatll be high on the priority list to fix but got dirty tires today while "flying" over a gravel trap but not actually touching the gravel. First video shows just that, second video is a comparison of the next corner, once normal and easily flat, once after the first video and understeering off the road
I did not see the videos but you can get dirty tires if you go wide in real life. Because you push the dirt just outside the ideal line
The car jumped on the curb and inside tires flew above the gravel, not touching it. But they got dirty anyway.
Just to add something to what Nico shown us, I consider that the dirty tires effect is exagerated in RaceRoom. On some tracks, you can't go on the curbs because you know you won't be able to take the next turn. In real motorsports, the curbs and run-off areas are the cleanest parts of the tracks as the cars spend the biggest part of their laps on them.