Always back up your profile in Documents\American Truck Simulator before changing versions.
Minimum NVIDIA GeForce GTX 660 or AMD Radeon RX 460; Recommended GTX 1660 or RX 590. Download File American Truck Simulator V1.31.1s.zip
Before downloading the file, ensure your PC can handle the base game. While this version is older, the general requirements for ATS are: OS: Windows 7/8.1/10 64-bit. Always back up your profile in Documents\American Truck
American Truck Simulator FPS Calculator & System Requirements Download File American Truck Simulator V1.31.1s.zip