— Ninja (@Ninja) April 17, 2018
As you can see, using a tire within a Port-A-Fort negates fall damage. In this clip, Ninja is at a height that would clearly be suicide if he fell, and he uses his Port-A-Fort followed by jumping on the tire to kill his opponent from above.
Of course, no that Ninja has done it, we can assume this “feature” is on their radar. Not sure if it is intended or not, or a side effect of the fact that landing on a tire also negates fall damage, but either way it should probably be fixed. However, we do love that players will always find a way to push the games physics and mechanics to the max.