I have play rF2 after a long time and update my content und software. After that i found a problem what i can not solved. In mirrors the tyres look someone white someone there are lost.
Did you update rfactor 2 to the latest build? You can try it with doing what is written here and see if it helps. And you can also try it with renaming the folder G:\Steam\steamapps\common\rFactor 2\UserData into Userdata_backup for example, before you start the game. You will get a complete new folder with the latest files then, that very often solves a lot of problems.