Tire balancing is a tune-up for your wheel-tire set. It makes sure that weight is evenly distributed around the entire circumference of the unit. The common symptoms of out-of-balance tires are uneven and faster tread wear, poor fuel economy, and vibration in the steering wheel, the floorboard or the seat that gets worse at faster speeds.
When all areas of the wheel-tire unit are as equal in weight as possible, the tire will roll smoothly. This helps it wear evenly, for longest life. Balancing also contributes to ride comfort: Imbalanced tires will wobble or hop up and down, which causes vibration. If a front tire isn't properly balanced you'll likely feel vibration in the steering wheel. If the problem is in the rear the tremor will be noticeable in the seat or floor.
Imbalanced tires are easily corrected, but the work is precise. It's done by attaching small weights, just fractions of ounces, to the wheel.
Everyday wear on tires will contribute to imbalance. Normal manufacturing imperfections are also a cause: Tires and wheels don't have precisely equal weight distribution. They'll be slightly heavier in some spots. Just half an ounce in weight difference is enough to cause a vibration when you're driving.
Rebalancing is done in a tire shop by putting the wheel-tire unit on a tire balancing machine that takes measurements to pinpoint lighter or heavier areas and making adjustments to account for these weight differences. The best time to get it done is when tires are being rotated, both for convenience and because you might have a tire out of balance on the rear of the vehicle and won't feel it until it is moved to the front.
Here's how it's done:
Though both should be part of regular auto maintenance, balancing isn't the same as getting an alignment. Alignment is about correcting the angles of the tires so they're properly positioned in relationship to each other and to the road. It gets the wheels all traveling in the same direction and makes sure the tires make contact with the ground as they should.
Vibration when underway could be caused by an imbalanced tire and wheel assembly or something else — a bent wheel, a damaged tire (which won't be fixed by balancing), worn suspension parts or other aging components. If you feel a vibration, don't wait to get it diagnosed. You'll head off other problems — and enjoy a smoother ride — when your tires are well balanced.