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Wheel balancing compensates for uneven mass distribution in a tire-wheel assembly. A balancing machine spins the wheel at high speed and uses sensors to measure the unbalance magnitude and angle at each correction plane.

Weights are then placed at specific locations on the rim to counteract the heavy spot. This reduces vibration transmitted to the steering wheel and vehicle body at highway speeds.

Clip-on weights attach to the outer rim flange using a spring-steel clip. They are mainly used on steel wheels and some OEM alloy wheels with suitable flanges.

Adhesive (stick-on) weights use a peel-and-stick tape backing and are placed on the inside of the rim barrel. They are preferred for alloy wheels because:

• No visible weights on the outside
• No risk of scratching or damaging the rim finish
• Better aesthetic appearance

For passenger cars, residual unbalance below 5 g per plane is generally acceptable. Most modern wheel balancing machines resolve to 1–5 g.

Unbalance above 10–15 g per plane usually causes noticeable steering vibration at highway speeds (80–120 km/h / 50–75 mph). Heavy trucks and commercial vehicles have higher tolerances due to larger tire mass.

A wheel can have two types of unbalance:

• Static unbalance — heavy spot in one plane, causes up-and-down vibration
• Dynamic (couple) unbalance — offset heavy spots in different planes, causes side-to-side wobble

Two-plane (dynamic) balancing corrects both components simultaneously. Single-plane correction only handles static unbalance and may leave a residual couple.

Static balancing corrects unbalance in one plane only. The wheel's center of gravity is moved back to the rotation axis. This is simpler but incomplete for wide wheels.

Dynamic balancing uses two correction planes (inner and outer) to eliminate both the force unbalance and the couple unbalance. This is the standard method for all modern passenger vehicles and provides the smoothest ride.