Usually on my cars (N scale) it's either the draft gear or the center sill causing the problem. If you have a loose piece of 15 inch radius track you can turn the car over, put the track on the wheels, and roll it back and forth to see where the problem is.
If not, my usual solution is to turn the trucks by hand and see what they hit first. Usually it's the draft gear, but N scale draft gear tends to be oversized anyway, so in your case it may be something else entirely.
Does your car have 3-D brake rigging? If so, one of the rods/pipes may be out of place, and the wheels are hitting it. If that's the case, you should be able to bend it out of the way, or, worst case, cut it off. If you have to cut, trim as little as possible, and it shouldn't be noticeable when the car is on the track.
You might check the coupler swing on this one. Sometimes, if the coupler is binding, it will force the entire car to the side, making it LOOK like the wheels are binding.
Now, if you have other KD boxcars that work fine, you can also do a very close inspection, and try to find anything that looks different.
If there is any irregularity in your track, it could even be that the truck screws are too tight, and the trucks can't rock enough to follow the track.
A long shot, but there might be a rough spot on either the truck or body bolster, and the truck only binds when turned as far as possible. That should show if you turn the truck slowly by hand.
It might even be the track itself, and the particular wheels on this car, combined with a slight flaw in the track, climb the rail. Do you have other cars with the same trucks or wheels?
Good luck!
