Wheel Balancing

The Ocala Jeep Club of Florida

Tire Balancing Technology by Ron Tyrie, II

It is a well-known fact that the only piece of equipment that separates your jeep directly from the road is the tires. There are many issues concerning tires such as tread style, wear characteristics, heat rating, load rating, and balancing. This month we will take a look at balancing and the different methods of making the highway ride a little bit better. A book could be filled with all the details and methods of balancing, for now we are only going to review the most basic and popular techniques.

Dynamic tire balancing is the most common way for a tire to be balanced. Basically a wheel weight is placed on either side of the rim in order to counteract imperfections of the tires or the rim. A lack of balance can be due to a few causes, but the chief causes of a tire rim package to be imbalanced is either tire/wheel run-out, or imperfections in the machining or rubber construction on the tire’s casing. Wheel run-out is basically how much the rim wobbles up and down or side to side. The method of dynamic balance is the best conventional way for a tire to have a complete balance. The main downside of the technique is that the outboard wheel weight is exposed to damage that can occur during an off-road excursion. Also some rims do not even have provisions to allow for weights to be mounted on lip of the rim. In that case there is no alternative other than static balancing.

The term “static balance” is where weights are placed only on the inside portion of the rim. The weights that are used for balancing in this way are referred to as “stick-on” weights because basically they have a strong tape backing which allows them to adhere to the rim or to the inside of the tire. Advantages for this type of balancing is that the weights usually can resist damage, and they do not interfere with the exterior appearance of your tire/rim package. Disadvantages for balancing this way is that the wheel assembly will not be completely balanced, so it ends up being a compromise between the vehicle owner’s needs and wants.

One of the best methods available today is called road or radial force variation balancing. This requires the use of a special balancing machine equipped with a roller on a robotic arm whose purpose is to exert rolling force onto the tire/wheel assembly. What this equipment does is measure how round the tire and wheel are under a true load. The data collected from the test is valuable because sometimes a tire may be “out of round” and still appear to be perfect. Once the machine determines the high spot (section of the tire that exerts the most force on the road) it digitally recommends an index position of the tire in relation to the wheel. Basically it tells the mechanic to spin the tire on the rim until the highest spot on the tire is even with the lowest spot on the rims run-out.

I hope that this will help to shed some light on the mysteries of tire balancing.