The term wheel runout or out of round refers to any component of a wheel or tire assembly that is not perfectly round. Radial runout is where the radius of the tire is not consistent from the wheel midpoint to any point on the rim. Too much radial runout can cause up and down vibrations which means there will be up and down hopping when it spins.
Radial run out as well as other wheel and tire malformations can be a cause of bumpy rides and sometimes even collisions. Lateral runout is the amount of sideways motion or the amount of “wobble” in a wheel or tire as it rotates which feels like dynamic imbalance problem.
Wheel Terminology Explained