By the time Tiger IIs entered combat, their operations were almost always defensive, never straying too far from their supply lines. This as apposed to early war years when tanks roamed far and wide, often many miles ahead of supply, thus necessitating large amounts of external stowage, even fuel drums, to be strapped on the vehicle. As for the spare track being attached to the bow armor of a Tiger II; in the hundreds of photos I have of Tiger IIs, I have never seen tracks attached to the front. With 8 sets of track hangers on the turret and the general shortage of spare tracks near the end of the war, indeed many vehicles had no spares at all, there would be little reason they would be on the bow.