There is a common misunderstanding between balancing the front tires and aligning the front wheels of a car. The procedure of balancing a tire is completely different than that of aligning the front end, not to mention that these procedures treat two totally different automotive problems. Here’s how tire balancing and aligning are different, how they are both accomplished, and how to tell if your car needs either one.
Tire Balance
The tell-tale sign of your tires being out of balance is usually a shake or vibration when driving at highway speeds. Generally, “the steering wheel shakes” is the top complaint customers come in with.
There are several reasons that tires can get out of balance, but usually it’s because of uneven wear. This is usually due to wear and tear on front-end parts, such as ball joints, tie rod ends, bushings, etc. However, sometimes it is just due to poor construction of the tire which makes it wear unevenly.
Balancing a tire involves the application of zinc, lead, or composite weights to the inside and the outside of the rim. The oldest way uses lead weights with clips that you pound onto the metal rim. On a fancier alloy rim, where an outside weight is undesirable, stick-on weights are carefully applied on the inside of the rim using laser guidance.
Lastly, for certain tires that require too much weight to balance, such as mud-terrain tires, there is the bubble balance. This balance involves applying a weight to the wheel creating a perfect balance when the tire is not in motion. It is the least accurate balancing technique but is the only method that works with oversized tires.
Tire Alignment
The tell-tale sign of your car needing a front-end alignment is that either your car pulls to one side or another, or your tires are wearing heavily on either the inside or outside edges. These symptoms are generally a function of one or more of three front-end geometries being out of whack. Here are the three.
Caster – The caster of a car is the angle between the pivot line (a line that runs vertically through the center of the upper ball joint to the center of the lower ball joint.) The caster of a car or truck can get out of spec if one hits a pothole, curb or some other object.
Camber – Camber is the angle from the top/bottom of the tire to the axle. If the top of the tire sticks out farther than the bottom, it is a positive camber. If the bottom of the tire sticks out more than the top, it is a negative camber. Like caster, the camber of a car or truck can get out of spec if one hits a pothole, curb or something else.
When to get a Front-End Alignment
There are several reasons that one should consider a front-end alignment.
New tires – Reedman-Toll Nissan of North Bethesda, a local Nissan dealer in North Bethesda, MD, says that it is a good idea to get an alignment whenever you get a set of new tires. This will assure that the front end is aligned properly so the new tires will start wearing evenly.
If a repair is made – If any front-end component is replaced on a car (ball joint, tie-rod end, steering rack, etc.) it is recommended that a front-end alignment be done to bring everything back to factory specs.
What’s Up with Four Wheel Alignment
It’s not just the front-end of a car or truck that may need alignment, newer SUVs with independent rear suspensions will accept four-wheel alignment. This is because the geometry of these independent systems can go out of spec just like the front. It isn’t as necessary to align the rear of an SUV when one feels front wheel wobble and shake but it should be done if the rear tires are wearing unevenly.