Sites like TruckyMods or the Steam Workshop are generally safer than generic file-sharing sites which may host "leaked" or "washed" files containing viruses. Installation and Setup If you are using a zip file for a mod or a manual patch: How To Upload & Unzip Mods To American Truck Simulator
For non-Steam legacy versions, check the SCS Software Forums for official patches and archived links. Download File American Truck Simulator V1.31.1s.zip
A new road through Yosemite (CA-120) was added, alongside new trailer types like bottom dumpers. Why Download the 1.31.1s Zip File? Sites like TruckyMods or the Steam Workshop are