Road Force Balancing

As straight forward as balancing your tires seems, advancements in automotive technology has made achieving an optimum ride a little more complex. Whether you drive a small sedan or a high horsepower supercar, the demand for more responsive equipment has led to tighter suspension and lower profile tires.

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As modern vehicles are evolving, the size of the original equipment wheel/rim manufatcurers are equipping on new vehicles is on the rise. The largest size wheel/rim used to average 15 inches, but now the average has increased to 18 inches and can even exceed 22 inches. This larger wheel/rim size also means a shorter tire sidewall for crisp handling and responsive performance. These features make vehicles more sensitive to vibration forces. Standard balancing often proves effective in addressing ride vibration problems. However, there are certain non-balance related factors that standard balancing doesn’t address.

Wheel and tire manufacturing is very precise, but some inconsistencies in weight, stiffness and balance are inevitable. Called lateral or radial runout, these inconsistencies are low or high points in the wheel and tire construction.

Some tires may have a spot that is stiffer than the rest of the tire. This condition is called force variation. Runout and force variation can cause noticeable ride vibrations. If standard balancing isn’t providing the smoothest ride, it is possible that runout or force variation are the real culprits. Match mounting and road force balancing can be used to counteract these issues.

What is Match Mounting and Road Force Balancing?

Match Mounting vs. Road Force Balancing Tires

A common solution to issues like lateral or radial runout and force variation is match mounting. Tire technicians mount a tire and wheel assembly together and align a marked point on the tire with the valve stem on the wheel. This aligned the high spot in the tire with the low spot in the wheel. However, this process is largely ineffective because the valve stem is no longer guaranteed to be the low point of runout in the wheel. Wheels have become more complex, making the valve stem placement cosmetic rather than strategic. Although match mounting can still produce positive results, the most reliable process for eliminating these non-balance based vibrations is road force balancing.

Road force balancing, sometimes called ride matching, is the most effective way to diagnose and resolve runout or force variation vibrations. A road force tire balancer uses a load-roller to simulate the force of the road and gather the combined uniformity of a wheel and tire package.

Road force balancers measure the force variation and runout of the whole wheel and tire assembly. It also measures and can distinguish between the radial and lateral runout of the wheel and tire individually, providing a more accurate account of the variant forces at work. This information is then used to determine what steps to take to compensate for any inconsistencies which can be simply adding weights or even remounting the tire and wheel to minimize the overall runout.

force diagram

A variety of factors might cause ride vibrations. Standard balancing, match mounting and road force balancing only address a few of the possible causes of ride discomfort. Road force balancing may only be recommended if standard balancing proves ineffective in diagnosing the issue. If both standard balancing and road force balancing do not address the issue, it is possible that the vibration source is not the wheel and tire assembly. Learn more about tire balancing.

If you have any questions or need any assistance, stop by your local Discount Tire and we'll get you taken care of.

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