Tires are not perfect. As much as they cost you would hope they would be, but there not. Minor imperfections in manufacturing or a slightly bent wheel can often cause tire vibrations. A tire/wheel combination that’s of balance is most noticeable between 60 and 70 mph. Above or below that speed the vibration is always less noticeable.
Most often a simply dynamic tire balancing can correct the problem. Spin balancing on a special tire balancing machine indicates where weights should be attached to balance out. But sometimes even this isn’t enough. When a tire is dynamically balanced but a vibration still exist, in comes “Road Force” balancing.
So what is road force balancing? Simply put, this special equipment goes one step further to assure a wheel/tire assembly is as balanced as good as it can possibly be by applying 1500 lbs of force to simulate vehicle weight, while spinning the tire to measure both dynamic and sidewall force. The sidewall force is measured in pounds of resistance with zero being ideal.
Once the measurement is taken, the machine will laser mark the tire and wheel with a recommendation to move tire position on wheel to minimize road force number. Zero simply means that there is no variation in measured pressure around the circumference of the tire. Normally anything above 10 lbs is excessive and will cause vibrations. Larger tires as for SUV’s or trucks have a larger acceptable limit.
The Hunter machine we have is state of the art and is nicknamed “The problem solver” because that’s exactly what it does, solve vibration problems. Technology is a wonderful thing!