Road Force Balancer: Difference between Normal vs. Road Force vs. Road Force Harmonic

[CedarZ4]

From reading through threads, it seems like the Road Force Balancer by Hunter is the most popular machine out there for balancing wheels. I called American Tires (a bimmerpost forum member had good experience there or normally I try to avoid chains - OT) and he offered me 3 different choices.

$15 for "normal" balancing using the same Hunter Road Force Balancer as the other 2
$20 for road force balancing
$25 for road force balancing with harmonics

What exactly is the difference between them all? I was not aware the machine had different settings… anyone familiar with tire balancing able to give a suggestion on which balancing method to use?

[HerrK]

Simplistically balance a tire mean you are ensuring that the heaviest spot in a tire/rim combination are "balanced" by adding weights to the opposite or lightest spot. Thus effectively if the tire/rim combination are setup on a "Frictionless" axle and tuned to any position the tire/wheel combination will not be affect by gravity - ie the wheel will not rotate.

The road force (RF) balance and RF+harmonics take into effect the minor out of roundness of the tire and stiffness of the tire.

Here's a reasonably good explanation of the RF and RF+Harmonics associated with balancing tires for your reading pleasure.

http://classic.artsautomotive.com/GSP9700.htm

http://www.barrystiretech.com/unifandbal.html

The Road force balance is usually acceptable unless you spend extended time at AutoBahn speeds.