Posted on April 13, 2020
Do you need tire balancing? What does that phrase mean, anyway? At Eastside Kia in Calgary, we want to help you understand what it means if your tires are out of balance, and to learn the signs you need tire balancing. Proper balance can extend the life of your tires, improve ride and handling, and increase fuel efficiency. Our Service Department will be happy to answer any questions you may have and make an appointment to get your tires balanced.
The terms tire balance, tire unbalance, and tire imbalance all mean the same thing conversationally, so you might hear them used interchangeably. However, note that tire balance is not the same thing as tire rotation or wheel alignment. Both of these services might be performed at the same time as balancing if needed, but they are separate processes. Our Service Department can perform any of these procedures if your vehicle needs them.
At its core, tire balance refers to the tire's distribution of mass. Ideally, a tire will have the same weight all the way around its circumference. But the stress of everyday driving can throw that distribution cold weather deflates tires, and sometimes the deflation is so severe that it causes unbalancing. Hitting a bad bump or pothole can bend a rim and cause the tire on that rim to become unevenly worn, or the force of the jolt can break a steel belt within the tire itself. Finally, wheel weights can fall off and unbalance the wheel and eventually the tire that's on it.
While you can't know for certain, there are clues that one or more of your tires may be unbalanced. A major hint is vibration at higher speeds, especially on the highway. An unusual hum can be a giveaway, as can steering wheel shake. You might also notice uneven or scalloped wear patterns or divots on your tires. Decreased fuel economy also could indicate an imbalance, since your drivetrain has to work harder to overcome the extra rolling resistance.
All of these could be indications of other mechanical problems or even foreign matter such as road tar or ice that has gotten into the wheels, but if it persists there's a very good chance that your tire balance is off. You might even be able to make a rough guess as to which end of your car has an unbalanced tire or tires: if the steering wheel shakes at speed, it's probably in front, but if you feel it only through the seats, it's probably in back.
Let's bring a little bit of physics into this discussion. Your tires and wheels are spinning when your vehicle is in motion, which increases their mass compared to when they're at rest. This means even a small imbalance becomes magnified and can have notable effects on ride quality, handling, and your car's fuel efficiency.
If you're noticing vibration or the steering wheel shaking only when braking, that's less likely to be a tire balance issue. In that case it's probably an issue with the brake rotors.
There are two main types of test for tire balance: the static balance test, and the dynamic balance test. The static test is cheaper and commonly available in tire shops and service centers, but the dynamic test can more accurately simulate the stresses in real-world driving.
In the static version of the test, the wheel and tire assembly is placed on a spindle that extends straight upward vertically. If the tire is properly balanced and its center of mass is right in the center where the spindle is, the weight will be distributed evenly and the spindle won't be pulled off vertical by the tire. If the spindle leans off vertical, the angle of deflection points to where the imbalance in the tire is. The degree of deflection indicates how severe the imbalance is.
In a dynamic balance test, the tire and wheel are mounted on a horizontal axis that spins at high speeds, simulating how the tire spins in real-world rotation. This is how tires are tested in the factory, and many shops and dealership service centres are equipped to perform this test. Note that there is some controversy about the precision of the test due to the fact that in real world driving, the tire and wheel combination is not free-spinning as it is on the dynamic balance machine. Rather, its motion is affected by contact with the road. Nevertheless, the dynamic balance test is usually considered more accurate and is the preferred test of well-equipped shops.
The tire balancing machine will show the mechanic where the imbalance is located and how much weight must be added to the tire and wheel assembly to counteract it. The mechanic will then attach stick-on or clip-on weights to the wheel or rim to counteract the imbalance. Properly applied, these weights should reduce the vibration and other symptoms of tire imbalance to an acceptable minimum.
Tire balance is a measure of weight distribution within the tire itself. Wheel alignment (which is sometimes confusingly called tire alignment) refers to the angle of the wheel that the tire is on, which also affects the angle at which the tire makes contact with the road. As such, it can cause uneven tread wear and steering wheel shake, just like tire imbalance. But a wheel that's out of alignment is more likely to cause the car to pull to one side or the other while driving and to cause the steering wheel to go off-centre.
The mechanic corrects wheel alignment by adjusting the suspension angles known as toe, thrust, camber and caster. Essentially the mechanic makes sure that all of the wheels are perfectly vertical and aligned in exactly the same direction. It's a good idea to perform a tire balancing at the same time as a wheel alignment to make sure the tires and wheel are all working properly for maximum tire life, ride quality, safety, and fuel efficiency. However, either procedure can also be performed alone.