In a perfect world, if wheels were perfectly-machined, if tires were perfectly round, and their casings and compounds are entirely uniform in properties, there would be no need for tire balancing. But there are always inevitably margins of error and variances in the above.
An average tire can weigh 20 pounds or so and generates a massive amount of centrifugal force at speed. Any variation in roundness or weight distribution leads to vibration issues.
Costs of Tire Balancing
The cost to balance tires is usually a package price for all four and varies from about $40 to $80. There are two basic types of balancing: dual plane and static.
Dual plane (or “dynamic”) balancing splits the wheel into two planes: the inner and the outer and balances them both down to zero separately. This is generally the most common and recommended.
Not all rims are designed for that and often, a static or single plane balance is done. That looks at the wheel as a single plane and applies balancing weights only at the center-line of the wheel.
The procedure is about the same either way and the cost to get your tires balanced is most often the same. Usually, the decision about what balance method will work best is left up to the mechanic doing the work.
What Exactly is Tire Balancing
Think of it like swinging a small weight on a string in a circle over your head. Whenever the weight is in the point of rotation, it pulls your hand toward that point.
A tire balancer spins the wheel and looks for that pull. It then calculates an exactly equal weight to place exactly opposite to the pull; effectively canceling out the imbalance and ideally, leaving exactly zero side-forces at the center point.
When road-speed-dependent vibrations are felt in an automobile, the general rule is that it will be a rotating part that is out of round or out of balance. By far the most common cause is a wheel out of balance.
If you feel it in the steering wheel, it’s probably a front tire. On the other hand, when you feel it in the rear chassis, it’s usually a rear tire. It’s most common and recommended that, when it’s necessary to check a tire for balance, you just go ahead and check them all and rebalance as necessary.
Road Force Balancing
The above balancing description refers to the old and common method of zeroing out the weight-related side forces at the center of a wheel’s rotation. Another less common problem is from road force vibrations where there is a variance in either the roundness of the tire or wheel or the stiffness of the tire sidewall.
Either one of these can also cause road-speed-dependent vibrations. A road force balancer is a machine designed to correct that.
It spins the wheel while using a roller to bear against the tire surface just as the road would. Then, it calculates the lowest point of the rim and the stiffest point of the tire sidewall and indicates those two points.
Rather than simply applying weights, this requires the tire beads to be dismounted and then, the tire is shifted on the wheel to the ideal position indicated by the machine. After this, conventional balancing still needs to be done.
Road force wheel balancing price varies from about $50 to $120. It’s worth noting that road force-induced vibration problems are rarely noticeable and the road force balancing is often only done when conventional balancing has failed to resolve vibration issues.
The machines are also more expensive and less common. Shops in many areas, if they don’t have a road force balancer, will often sublet vehicles needing that service out to a shop that does if necessary.
If conventional balancing doesn’t resolve an issue, road force balancing is also a good way to check the tire for out-of-roundness, to check for flat spots on the tire, and to rule out a bent rim. In both cases, the tire/rim assembly can be perfectly balanced but still cause noticeable problems on the road.
A road force balance should catch any of those problems if they are not otherwise obvious.
Tips for Getting the Best Service
- Go back to the shop where the tires were purchased, if possible. Many shops will rebalance tires they installed for free and will have some incentive to do the work quickly and well to keep you as a customer.
- Pay attention to exactly when the problem occurs. A wheel balance issue will usually be most noticeable at certain speeds – 50 to 75 mph, typically. A tire roundness or road force issue is usually more noticeable at lower speeds. Letting the shop know when the problem occurs helps greatly in diagnosing the problem and verifying that it has been solved.
- Allow time for the work to be done. If it’s a simple rebalance, it’s common enough to have the service done while waiting as it takes only about half an hour. But if the problem isn’t easily resolved, then, more than one attempt might be necessary and the vehicle might need to be test driven more than once.
- Rule out other problems. One of the most common non-mechanical things that can cause an imbalance, especially in winter, is mud, ice, or debris in the wheels. Cleaning or hosing out the wheels is one thing that tire shops have to do regularly before balancing tires.
What Can Go Wrong
The most common problem is that wheel weights can fall off. Weights are of two types: either clip-on or adhesive mount.
Adhesives don’t always stick perfectly and it’s often a challenge to prepare a dirty, rusted, or even corroded rim surface adequately for good adhesion. Clip-on weights have a few varieties to fit different rim profiles, but there are far more different rim profiles than there are wheel weight varieties.
In most cases, the shop will use what fits best, but sometimes, a weight will work loose. If the weight comes off, the wheel is no longer in balance and vibration might be felt.
The simple solution is to take the vehicle back to the shop and let them know. It is a common thing to have to re-check tire balances.