American.truck.simulator.v1.46.2.11s.part2.rar -

Open the resulting folder and run setup.exe or the game executable.

Right-click on Part 1 and select "Extract Here" using WinRAR or 7-Zip . The software will automatically pull data from part2.rar and subsequent volumes. American.Truck.Simulator.v1.46.2.11s.part2.rar

Ensure you have all parts (part1, part2, etc.) in the same folder. Open the resulting folder and run setup