CARS.COM — Smooth driving is a balancing act that requires getting the wheels and tires to spin at high speeds without vibrations. That's not a slam dunk; a dirty little secret about car wheels and tires is that they usually aren't perfectly round, even when brand new. What's more, their weight often isn't evenly distributed, so they're heavier in some spots than others.
Either issue can cause annoying vibrations. Out-of-balance tires can also cause rapid tire or suspension wear, so it's not just about ride comfort.
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That is why when new tires are mounted on wheels, mechanics spin-balance them to detect and eliminate vibrations before mounting them on the car. Some vibrations can be eliminated by rotating the tire on the wheel so the heavy or high spot is in a different location that better matches up with the wheel. Small weights are attached to the rims with adhesives or clips to counteract the heavy spots and provide a smooth ride. Over time, though, the wheel weights can fall off. If that happens to a front wheel, you may feel vibrations through the steering wheel that typically become more pronounced as vehicle speed increases. Vibrations from an imbalanced tire can also be felt through the floorboards.
Many tire dealers include free lifetime rotation and tire balancing with new tires (something you should ask about before buying). Tire rotation is when the tires are removed and reattached at a different position on the vehicle to ensure they wear evenly, which should be done as regular maintenance according to the automaker's recommendation, every 5,000 to 7,500 miles on most vehicles.
Many consumers neglect the balancing part and have their tires rotated only periodically. If balancing was included with your tires, it would be wise to remind the shop to check the balance at the same time. Even if balancing costs extra, it's a good idea to have it checked at least every two years, or more often in areas where roads are not well-maintained.
Vibrations can also be caused by a bent wheel, a damaged tire (which won't be fixed by balancing), worn suspension parts or worn wheel bearings, so wheel and tire balancing may not eliminate all vibrations.
Tires and wheels are balanced before being attached to the vehicle by spinning them on a machine that identifies heavier or stiffer spots that cause vibrations. Some tire dealers and repair shops balance tires on "road force" machines that simulate the weight and forces applied to tires and wheels during driving conditions. They say this method detects tire imperfections and provides more accurate and detailed readings that allow more precise wheel balancing.
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