Ported maps surface traction

I saw there's a lot of ported maps from ACC and other games. Like nordschleife and every other map. They grip different from official race tracks, my guess it's probably because ported maps' surface is actually a "grid map" surface and not an actual "asphalt"? Am i right on this?

 

you can edit the grip levels per material, so if the port is done correctly then the road should have asphalt grip, grass would be grass and so on. Also,I think that the default grip is equal to the one on asphalt