[Imp]

In the game it generally happens in mud, snow, water obstacle or rough especialy slopes. Not really modeling a flat tyre more you broke something or got stuck proper.
Have had instances especialy on rough slopes where rocking has worked but freeing yourself can often be difficult.
Rough slopes so long as suspension is not broken & you dont slide in a dip probably easiest, you can always go very slowly back down if you are not wedged.
Snow seems to normally require a fair amount of digging to get going, mats etc. if there is any sort of slope involved ice or powdery conditions its going to be fun.
Sreams & proper mud trying to get out or press on when its bad can make maters worse.
Once it gets a grip on bodywork it sucks to it very hard to get out of, my worst case took 5 vehicles, 3 on reasonably firm ground and 2 winched one to the other to reach me. Previous attempts just pulled the winching vehicles to me & if anything got me more stuck. You need to be real careful you dont get stuck to get onto your vehicle not in the mud if possible.