^On a coaster, not all the wheels touch the track at the same time, this is what gives the train the movement to travel around a big twisted track, if all the wheels touched the track at the same time then the train would have a hard time moving around.

Actually, it is when the wheels are not in constant contact with the track that coaster trains have problems travelling through the course. Roller coaster designed by Vekoma and Arrow Dynamics normally do not have spring-loaded wheels, or some other assembly that keeps the wheels in contact with the track. ?This causes "hunting" which results in the side-to-side and up-and-down "roughness." When the wheels are in constant contact (Intamin, B&M) the train cannot "hunt" and does not experience any of the roughness associated with loose wheels.