Since a tire is made by bonding together rubber, there is a in difference in the rubber thickness, the circumference of the tire is not a perfect circle.
Even if the tire is perfectly circular, if the tire’s rotation center and the axle are not the same when installing, the tire will become eccentric.
Radial run-out
When rotating the tire that has a radial run-out, the rotational radius of the tire increases and decreases, bouncing the vehicle up and down each time the tire rotates. This in turn, causes “shake”. Possible causes of radial run-out are tire run-out, wheel run-out and the improper installation of the wheel and axle hub.
Lateral run-out
When the tire or the disc wheel has lateral run-out, uneven wearing and unstable driving will be caused. Possible causes of lateral run-out are expansion in the tire’s side wall or wheel damage.
When troubleshooting for the cause of run-out, not only a tire inspection but also a disc wheel and an axle hub inspection is required.