In Spintires, vehicles are not automatically in "off-road mode." They often start in RWD (Rear Wheel Drive) with an open differential to save fuel and protect the drivetrain on roads.
Here’s why, along with a more helpful alternative direction: spintires steamunlocked
and the implications of using the third-party site SteamUnlocked to acquire it. 1. Game Status: Spintires In Spintires, vehicles are not automatically in "off-road