These are textures only for Green Guayule tires.
1. Make sure you have the extension folder for firestone tires in the RSS Formula Americas 2020 car folder which you can get here.
2. Open the rar file and paste the textures in the extension folder.
Note: It will replace the red soft tyres so its recommended you back the red soft tyre textures up. Due to the name of the textures, you will need to select the soft tyre compound for the car. P.S., I'm not sure if you can drag and drop individually in each skin but go ahead and try.
1. Make sure you have the extension folder for firestone tires in the RSS Formula Americas 2020 car folder which you can get here.
2. Open the rar file and paste the textures in the extension folder.
Note: It will replace the red soft tyres so its recommended you back the red soft tyre textures up. Due to the name of the textures, you will need to select the soft tyre compound for the car. P.S., I'm not sure if you can drag and drop individually in each skin but go ahead and try.