Maintaining the tyre balance on your vehicle is critical to ensure satisfactory service from your tyre investment. In addition to providing a smooth ride, balancing is a key component in tyre wear.
Vehicles today are being made lighter and lighter. The heavier cars of yesterday actually helped smooth out the ride by dampening many vibrations before the driver could feel them. Generally, more responsive tyres with lower profiles (which send more road feedback to the driver) are being used in today’s style- and performance-oriented market. As a result, even the slightest imbalance can be felt in most modern vehicles. This is significantly less than the average of ten years ago. For those of you who have plus-sized your tyres, tire alignment, wheels balancing is even more critical.
The Balancing Act
a tyre is mounted onto the wheel, two slightly imperfect units are joined to form an assembly weighing forty pounds (this is the average for cars). The chance of this assembly having absolutely precise weight distribution about its radial and lateral centers is virtually impossible. The illustration below shows how an imbalance creates vibration.
Occurs when there is a heavy or light spot in the tyre that prevents the tyre from rolling evenly and causing the tyre and wheel to undergo an up-and-down motion.
Occurs when there is unequal weight on one or both sides of the tyre/wheel assembly’s lateral centerline, thus creating a side-to-side wobble or wheel shimmy.
The static imbalance creates a hop or vertical vibration. The dynamic imbalance creates a side-to-side or wobbling vibration. Most assemblies have both types of imbalance, and require dynamic balancing to create even weight distribution.
Keeping Your Tyres Balanced
Over the miles, turning left and right, hitting bumps and holes you could not see or avoid, and driving down uneven road surfaces have led to uneven tread wear on your tyres. Besides rotating the tyres and getting an alignment to set things right, you should also rebalance the tyres. The uneven tread wear has created an imbalance that generates excessive heat and wear on your tyres. If you live near one of our stores, you should ask about the Lifetime Balancing program. For a nominal, one-time charge you can have your tyres balanced at every rotation.
Other Sources of Vibration
Very often the wheel/tyre assemblies on a vehicle may be in balance but you can still feel a vibration. Here are some of the other causes of vibration:
- Bent wheel
- Tyre out of round (radial or lateral runout)
- Wheel-to-axle mounting error
- Inconsistent tyre sidewall stiffness (force variation)
- Brake component wear or failure
- Drive train or engine component wear or failure
- Suspension wear or failure
- Wheel bearing wear or failure
- Wheel alignment is out
Balancing High Performance Tyres and Wheels
Today’s high performance tyres and wheels come with features that facilitate optimum mounting. Wheels are marked to identify the minimum radial run-out spot (low point) on the bead seat surface. Tyres are marked with a high point location. Mounting the assembly to match these two points is called match mounting.
On rare occasions, a tyre may be manufactured with slightly inconsistent sidewall stiffness (creating what is called force variance) which leads to a ride problem. A new generation of balancers can detect this condition, and can also guide tyre technicians to remount the tyre in an optimum position that puts the assembly within specification and eliminates the problem. If specifications cannot be achieved, the defective tyre will be identified for replacement.
Wheel Weight Placement
Many of today’s wheel designs necessitate unique wheel weight placement to achieve both precise balance and aesthetic appeal. Your tyre dealer will inform you of the best method for your wheel type.
- Clip-on weight
Standard balance uses only clip-on weights as shown. This method is usually done on original equipment steel or alloy wheels. Different type wheel weights are used for each type of wheel.
- Combo weight
Mixed weights balance uses both clip-on and adhesive weights. The balance planes maintain the weights behind the face of the wheel.
- Adhesive weight
The use of adhesive weights is typically reserved for chrome or other wheels with a delicate finish. The balance planes maintain the weights behind the face of the wheel.
If you’re interested in learning more about better tyre wear, see our articles on Air Pressure, Tyre Rotation, and Alignment.