March 2013, TruckingInfo.com - WebXclusive
People will tell you that wheel balancing isn't necessary these days. Going back 10 or 20 years, new tires often needed a small amount of weight to balance out the irregularities in the old production process. With today's more exacting manufacturing standards, irregularities are the exception. Overall, new premium-brand tires are much better balanced than in the past.
Tire wear associated with balance problems often appears as cupped channels along the tread face of the tire. (Photo: TMC)
So, can we forget wheel balancing? It wouldn't be the end of the world if you did, but it will probably cost you in tread life and driver complaints. You see, the tire is just one part of a system that includes the tire, the wheel, the hub and the brake drum. They all rotate around the spindle at about 500 rpm at highway speed. Any one of those components could off balance.
Achieving good wheel balance -- not just tire balance -- starts with proper mounting. The tire must be concentrically mounted on the wheel, says Guy Walenga, director of engineering for commercial products and technologies, Bridgestone Americas.
"To get it right the first time, you need to lubricate the bead seat area on both sides of the tire as well both flanges on the wheel," he says. "Contrary to popular belief, lubricating the bead seat and tire bead is not to make it easier to slide the tire over the rim flange, it's to help those surfaces seat properly, and the help the tire bead slip up onto the 15-degree bead seat of the wheel. As the inflation pressure increases, the tire is pushed into the proper position on the wheel by the equal force applied all around the tire by the increasing pressure."
With the tire partially inflated, the installer should check the guide ring located near the bead to ensure equal spacing between the ring and the wheel flange the full 360 degrees around the tire.
"This is visual check," Walenga says. "You can see if the space between the guide ring and the flange are different anywhere around the tire. If it is, you must deflate the tire and try again."
By ensuring the wheel is concentrically mounted, you'll eliminate at least one cause of irregular tire wear -- radial runout, or an out-of-round condition -- and one suspect in your wheel balance challenges.
At this point, dynamic balancing is useful -- at least as a troubleshooting tool. Once the tire and wheel are dynamically balanced, they can be dismissed as causes of vibration.
If dynamic balancing is not to your taste, then some internal or external balancing tools can help.