Tires and wheels are pretty heavy. When a tire is mounted on a wheel, it is usually not perfectly balanced. So the tire technician will spin the tire on a machine to determine where it’s too heavy. He will then place weights on the wheels in strategic locations to balance it out.
When a tire is out of balance, it actually bounces down the road instead of rolling smoothly. Since the average size tire rotates at about 850 revolutions per minute at 60 MPH, it is actually slamming into the pavement 14 times a second. That’s where you get your vibration.
Most high-quality tires hold their balance pretty well. They just get out of balance gradually with normal wear and tear. If you suddenly feel a vibration, it is probably because you lost a balance weight along the way. Definitely get a balance if you feel a vibration, change your rims or have a flat repaired. Putting off a needed balance job leads to excessive tire wear, wear to your shocks, struts, steering and suspension parts. A balance not only improves your ride and handling, but also can save you some big repair bills and possibly an accident. Additionally, you will get better gas mileage.