In short. Balancing adds small weights to a wheel and tyre so that their mass is spread evenly round the axle. A machine spins the assembly, measures what is off, and says how much weight to place and where. The reason it matters is speed: the same 20 g imbalance pulls on the hub with about 7 N at 30 mph and 51 N at 80 mph, seven times as much, which is why a wheel that feels fine in town shakes on the motorway. Do it whenever a tyre is fitted or refitted, after a repair, a rotation or a hard kerb strike, and whenever a vibration appears. It will not fix a buckled wheel, a wheel that is not centred on the hub, or nuts tightened unevenly; and it is not alignment. The MOT has no item on balance.
What balancing does
A wheel and tyre are never perfectly even. Michelin notes that when tyres are fitted, a slight imbalance in the tyre or the wheel can combine and amplify the dynamic imbalance, so it says dynamic balancing should be carried out systematically whenever tyres are replaced or refitted (Michelin).
Continental describes two methods (Continental UK):
- Static balancing is for a slight imbalance. The assembly sits on a vertical spindle, the heavy side sinks, and a small weight, fractions of an ounce, goes 180 degrees across the plane of the tyre.
- Dynamic balancing is for more complex imbalances. A computer balancer spins the assembly, at 10 to 60 mph on Continental's description, and measures it on all three axes. Weights go on both the inner and outer sides of the rim, so the machine corrects the wobble across the width of the wheel as well as the up-and-down hop.
Continental also describes road force balancing, in which a roller presses against the tyre to simulate the force it feels on the road; it says that can detect and correct imbalances that regular balancing might miss (Continental).
Why speed is the whole story: the numbers
An imbalance is a small extra mass at some distance from the axle. As the wheel turns, that mass pulls the hub outwards with a force F = m × r × ω², where ω is the rotation rate, which is the car's speed divided by the tyre's radius. Because the speed is squared, the force grows far faster than the speed.
The table below is our arithmetic, not a measurement on a car. It takes a 205/55 R16 tyre (outside diameter 631.9 mm, so a radius of 0.316 m) and puts the extra mass at the radius of a 16-inch rim (0.20 m); the rolling radius is taken as the free radius.
| Speed | Wheel turns per second | 10 g imbalance | 20 g imbalance (0.7 oz) | 40 g imbalance | 20 g in pounds-force |
|---|---|---|---|---|---|
| 30 mph (48 km/h) | 6.8 | 3.6 N | 7.2 N | 14.4 N | 1.6 lbf |
| 50 mph (80 km/h) | 11.3 | 10.0 N | 20.0 N | 40.0 N | 4.5 lbf |
| 60 mph (97 km/h) | 13.5 | 14.4 N | 28.8 N | 57.7 N | 6.5 lbf |
| 70 mph (113 km/h) | 15.8 | 19.6 N | 39.2 N | 78.5 N | 8.8 lbf |
| 80 mph (129 km/h) | 18.0 | 25.6 N | 51.3 N | 102.5 N | 11.5 lbf |
From 30 to 80 mph the speed is multiplied by 2.7 and the force by 7.1. A newton is about a tenth of a kilogram-force, so 51 N is about 5 kgf, applied once per turn, 18 times a second. Conversions use the NIST factors (NIST SP 811).
The force alone does not tell you why the vibration comes and goes. Michelin gives the other half: an imbalance is sometimes felt only at particular speeds, because of the vibrations of the suspension and the vehicle structure. That is why a vibration can sit in one band of speeds and be gone above or below it.
When to balance
| Situation | What the sources say |
|---|---|
| A tyre is fitted or refitted | Michelin: dynamic balancing systematically whenever tyres are replaced or refitted |
| New tyres, rims or wheels, a rotation, a tyre repair | Continental UK lists all four |
| A hard kerb strike or a large pothole | Michelin: the rim may be damaged and need rebalancing; Continental lists a large pothole |
| Routine | Continental UK: every 3,100 to 6,200 miles or 1 to 2 years, and also "no fixed intervals that apply to all vehicles" |
| A vibration appears | Both name vibration as the main sign |
Continental's page puts balancing at every seasonal change of wheels down to personal preference. Its routine range (3,100 to 6,200 miles, or 5,000 to 10,000 km, or 1 to 2 years) comes with the statement on the same pages that no fixed interval applies to all vehicles, so treat the range as a rule of thumb.
What you feel, and what else it can be
Continental lists vibration in the steering wheel, seat or floor, often worse at higher speed; uneven or faster tyre wear; higher fuel consumption; and unusual road noise, and says an imbalance is more noticeable on larger wheel diameters. Michelin adds the dashboard. Neither says which wheel is at fault from where you feel it.
If the vibration stays after a balance, balancing was not the cause, or not the only one:
| What you notice | What it can mean | Where it comes from |
|---|---|---|
| Vibration remains after balancing | A wheel that is out of round (buckled) | Porsche's limit for the bare wheel is a radial and lateral runout under 0.7 mm; see alloy wheel repair |
| A fresh balance on a precise wheel that does not cure the vibration | The wheel may not have been centred on the machine | Porsche: only use the maker's centring set for balancing |
| Vibration after the wheels were refitted | Dirt between wheel and hub, or nuts tightened round the circle and not crosswise | EUWA: risk of vibration; see wheel nut torque |
| The car pulls to one side or the tyre wears on one edge | Alignment, not balance | Michelin and Continental: balancing is about the tyre and wheel assembly, alignment about the angles of the wheels |
EUWA says the faces between the wheel and the hub must be clean and that tightening clockwise or anticlockwise, not crosswise, risks deforming the wheel centre and vibration (EUWA ES 1.07, 3.1 and 3.6).
Weights: types, materials, where they go
A weight is either a clip that hooks over the rim flange or a strip with adhesive that sticks inside the rim. Michelin's page says steel rims take clip-on weights on the flanges and aluminium rims take adhesive weights behind the spokes, and Continental says weights are clip-on or adhesive.
Two rules from the wheel makers and the law:
- Match the flange. EUWA says the type of balance weight, when used, must be in accordance with the profile of the rim flange (EUWA ES 1.09, 2.6).
- Plain lead is out. The end-of-life vehicles directive bars lead from the materials and components of vehicles put on the market after 1 July 2003, except in the cases listed in its Annex II (Article 4(2)(a)). Annex II, as published on legislation.gov.uk, tolerates up to 0.1 per cent lead by weight in a homogeneous material, lists some alloying uses, and says its exemption for spare parts for older vehicles does not apply to wheel balance weights (Annex II). We found no entry that lists balance weights. That is the directive as held on that site, and we have not checked how each country applies it.
The weights go where the machine says, on the inner and outer planes. With a polished, painted or diamond-cut face, ask the fitter to place the weights behind the spokes or inside the barrel, where they cannot touch the finish, and not to clip anything onto the visible lip. Porsche's bulletin makes the same point for its wheels: improper handling can damage the wheel surface, tyres are to be removed and mounted with a bead holding-down device only, and a leather pad is to support the valve insertion tool.
Centring and matching: the details that matter on a good wheel
A balancing machine reads the imbalance about its own spindle. If the wheel is not centred on that spindle, the reading is of something else. How a wheel is centred depends on how it fits the car: EUWA says wheels that centre on the hub spigot are made to a reduced dimensional tolerance, so that they are centred accurately (ES 1.02, 2.2); a wheel that is centred by its bolts relies on the cones or balls of its bolt holes. The centre bore and bolt circle are explained in the PCD and centre bore guide. Porsche's instruction is short: only use the Porsche centring clamping set for balancing.
Porsche also describes matching, which is turning the tyre on the wheel to find the position in which the pair runs most smoothly. In uncontrolled matching, the tyre is turned by 90 or 120 degrees if needed to reach an acceptable rolling smoothness (true running, imbalance and the distribution of the weights). In controlled matching, a balancing machine with a matching programme usually gives an even better result. The same bulletin gives runout limits: under 0.7 mm radial and lateral for the wheel, under 1.25 mm for the wheel with its tyre. And it asks for new valves whenever tyres are changed, and for no extreme acceleration or braking in the first 100 to 200 miles on new tyres, to keep the tyre from turning on the wheel (Porsche bulletin 38/25).
These are one car maker's instructions for its own wheels. They show the care that a precise wheel and a precise fitter share.
What to ask your fitter
- Will the wheel be centred on the machine with the right cone or plate for this wheel?
- Which weights will go on, and where: behind the spokes or inside the barrel, adhesive and not clip-on, if the face is polished, painted or diamond-cut?
- Will the tyre be matched to the wheel, and will the wheel be read for runout first?
- Will the valve be new, and the sensor refitted correctly if the car has them?
- Will the nuts be tightened with a torque wrench, crosswise, to the car maker's figure, and checked after 50 to 100 km? See wheel nut torque.
What balancing does not fix
- A buckled wheel. A weight compensates for a difference in mass, not for a wheel that is out of round.
- A wheel that is not centred or not seated. Dirt between the wheel and hub, or the wrong spigot ring, makes the same symptom.
- Uneven tightening. See above.
- Alignment. Michelin and Continental say alignment adjusts the angles of the wheels to the car maker's figures; balancing concerns the tyre and wheel assembly.
- A tyre defect. Continental's road force method looks for tyres or wheels that are not perfectly round or not evenly loaded.
The MOT
Section 5 of the MOT inspection manual, on axles, wheels, tyres and suspension, has no item on wheel balance, so a wheel that vibrates is not a failure on its own account (MOT manual). The same manual does fail a badly distorted wheel (major) and any fracture (dangerous): the buckle that causes a vibration can be the thing that fails. See the guide to the MOT and new wheels.
Wheels from Onyx Forged
Whoever fits the tyres to a set of Onyx Forged wheels does the balancing. The Onyx Forged design office works out the wheel for the car as you described it. If you want the finish and the weights to be discussed before the tyres go on, write to customer service, and show the fitter what the finish is. A lighter wheel changes how much a given weight matters; for that, see lightweight wheels and unsprung weight.
Frequently asked questions
What does wheel balancing do?
It spreads the mass of the wheel and tyre evenly round the axle by adding small weights where a machine says. Without it, a heavy spot pulls on the hub once per turn and the force grows with the square of the speed: 7 N at 30 mph and 51 N at 80 mph for a 20 g imbalance in our calculation.
When do you need to balance your wheels?
Whenever a tyre is fitted or refitted, after a tyre repair, a rotation, a hard kerb strike or a large pothole, and when a vibration appears. Continental gives a routine interval of 3,100 to 6,200 miles or 1 to 2 years, and also says no fixed interval applies to all vehicles.
What are the signs of unbalanced wheels?
Vibration in the steering wheel, seat, floor or dashboard, often worse at higher speed; uneven or faster tyre wear; higher fuel consumption; and road noise. They can have other causes, so balancing may not remove them.
Why does the vibration only happen at certain speeds?
The force grows with speed, but the car's suspension and body also have natural vibrations, and an imbalance can show only where the two meet, in Michelin's account. That is why a wheel can shake at 60 mph and be smooth at 80.
What is the difference between balancing and alignment?
Balancing deals with the weight of the tyre and wheel assembly. Alignment adjusts the angles of the wheels to the car maker's figures, and is about the suspension. A car that pulls to one side or wears a tyre on one edge points to alignment.
Do you need to balance after rotating tyres or repairing a puncture?
Continental lists both a rotation and a tyre repair among the times to balance. Michelin's rule is to balance whenever a tyre is fitted or refitted.
What are wheel weights made of, and which suit alloy wheels?
Clip-on weights go on the flange of a steel rim; Michelin says aluminium rims take adhesive weights behind the spokes. Lead is restricted by the end-of-life vehicles directive, whose exemption for spare parts excludes wheel balance weights. The type has to match the flange profile, says EUWA.
Will balancing fix a buckled wheel?
No. A weight cannot make a wheel round. A wheel that stays out of true after balancing needs a runout reading; Porsche's limit for its own wheels is under 0.7 mm radial and lateral for the bare wheel.
Where to go next
If the vibration comes from a wheel, read alloy wheel repair and wheel nut torque. For why mass at the wheel matters to the car, see lightweight wheels and unsprung weight; for the tyre side, how to read a tyre size; and for steel against alloy and their weights, alloy against steel wheels. Onyx Forged is a French brand of made-to-order forged wheels, designed to JWL/VIA standards: see Onyx Forged and the catalogue.
Sources
- Continental, balancing tyres (UK); Continental, balancing tires (international).
- Michelin, wheel alignment, wheel balancing: when to do it? (Michelin Middle East).
- Porsche AfterSales, bulletin 911 (992) 38/25 (7 October 2025).
- EUWA, ES 1.07 (June 2020); EUWA, ES 1.09; EUWA, ES 1.02 (May 2011).
- Directive 2000/53/EC on end-of life vehicles, as held on legislation.gov.uk: Article 4 and Annex II.
- GOV.UK, MOT inspection manual, section 5.
- NIST Special Publication 811, Appendix B.9, conversion factors.
All pages were read on 15 October 2026.
The Onyx Forged design office.