Same way you move a LAV....................Tell the driver to advance
Now, have you changed your opinion based on vehicle width? Or is this about the speed thing?
Why are you traversing a narrow mountain pass? Normally they are avoided regardless of Veh type
However, if you mean can they move through a long defile (such as a mountain pass), then that is a tactical command level decision. It would be based on intelligence and the ability to support such a movement.(air or ground recce, map info, sat imaging, or eyes on the ground) Same for any movement that funnels vehicles or personel through a tight route/location be they MBT, LAV, HLVW or G Wagons
You are seriously out of your league here
Wheels are outstanding on hard surface. Tracks (MBT's) are designed for their cross country capability. (research characteristcs of Armour) Once you leave the hard stand, 99% of Crewman would rather be rolling on tracks
You do not have turret time, obviously. Nor do you have track experience.
Time to go back to your "Soldier of Fortune" magazine and pick a different topic. (read one of the long articles that gives you more info and come back better armed)