In short. The centre bore is the hole in the middle of a wheel. On most cars it fits over a raised collar on the hub, the spigot, and that fit is what puts the wheel on the hub's axis. A hub-centric ring (also called a hub ring, spigot ring or centring ring) is a plastic or aluminium ring that fills the gap when the wheel's bore is larger than the hub, which is usual when one wheel is sold for many cars. It centres the wheel; it does not hold it on: that is the job of the bolts or nuts, tightened to the car maker's torque. Its outside diameter is the wheel's bore and its inside diameter is the hub's, and both are measured with a calliper. A ring is pointless when the bore already matches the hub, and impossible when the bore is smaller. Why it matters is speed: our calculation shows that a 20 kg wheel and tyre sitting 1 mm off the hub's axis pulls on the hub with about 196 N at 70 mph, the effect of a 100 g imbalance. The MOT has no item for rings, but it fails a wheel and fixings that are not compatible and a worn spigot.
Hub-centric or lug-centric: two ways to centre a wheel
A wheel can be put on the hub's axis in two ways, which the Association of European Wheel Manufacturers (EUWA) describes in its standard ES 1.02.
| Hub-centric (spigot centring) | Lug-centric (stud centring) | |
|---|---|---|
| How it works | the centre bore fits closely over the hub's spigot | the nuts or bolts, through a conical or spherical seat, pull the wheel into position |
| What the EUWA says | wheels for this method are "manufactured to a reduced dimensional tolerance to ensure that the wheel is centred accurately, and the load is transmitted to the hub effectively" (2.2) | the wheels "rely on the studs to centre the wheels on the vehicle hub", most commonly through countersunk holes, and "great care must be taken" to match the nut and washer to the seat (2.3) |
| Where you meet it | most original wheels on passenger cars, in the sources we read | many aftermarket wheels, bored large so that one wheel fits several hubs |
Before either, the EUWA sets a rule that covers both: "the wheel disc must exactly correspond to the vehicle axle hub", in the diameter of the centre hole, the diameter, number and shape of the stud holes, and the offset (ES 1.02, 2.1).
Charles C. Roberts, Jr., a consulting engineer in accident reconstruction and failure analysis, sets out the difference in Machine Design. With a hub-centric wheel, the hub supports the wheel together with the studs. With a lug-centric wheel, the studs centre and support it alone, because there is a gap between the wheel and the hub. He considers hub-centric fitting better suited to cars, because the hub's support stands up better to the shocks of ordinary roads, and describes what can happen when a lug-centric aftermarket wheel goes on a car designed to be hub-centric: without the hub's support, shocks can bend the studs until the wheel is no longer concentric with the hub, with vibration and loss of clamping, and he reports two cases of fatigue failure of studs or bolts, one of which ended with a wheel coming off. It is one engineer's opinion, published in 2016, not a test or a standard.
What a ring does, and what it does not
A ring is the answer both Machine Design and a US tyre network give to that gap. Machine Design writes that some makers supply a piece that fills it, touching both the wheel and the hub, and carries the loads from the studs to the hub. The tyre network writes that lug-centric wheels, correctly fitted with rings, can give the same stability, precision and comfort as hub-centric ones. Neither puts a number on it.
Three claims you will read elsewhere need care.
| What you read | What the sources we read say |
|---|---|
| "the ring won't bear any weight once they're fastened", the nuts or bolts (a US wheel seller's blog, among the first results for the query) | Machine Design describes the ring as "a means of transferring lug loads to the hub". Neither page measures it. Our reading: in normal driving the wheel is held by the clamping force of the fixings; the disagreement is about shocks, and nobody we read has measured it. |
| Lug-centric installations "are safe but often result in annoying vibrations" at high speed (the same blog) | The EUWA treats stud centring as a method in its own right, for wheels designed for it (2.3). Off-centre is one cause of vibration among several. A ring does not correct an imbalance, a buckled rim or unevenly tightened nuts: see our guide to wheel balancing. |
| A ring is optional and only affects comfort (a common line of argument; our summary, not a quotation) | The EUWA asks for the centre hole to correspond exactly to the hub (2.1). Whether a given wheel needs one is in that wheel's documents, not in a general rule. |
Our calculation: what 1 mm off centre costs
A wheel and tyre are balanced around their own centre bore. If that bore sits a distance e away from the hub's axis, the whole assembly turns around the wrong axis, and its mass acts like an imbalance: the force on the hub is F = m × e × ω², where ω is the wheel's speed of rotation. The offset cannot be more than half the difference between the bore and the hub, because the spigot would then touch the wall of the bore.
Assumptions, ours and stated: a wheel and tyre of 20 kg, balanced around its bore; a 205/55 R16 tyre (outside diameter 631.9 mm), the same basis as our guide to wheel balancing.
| Off centre by e | Gap between bore and hub that allows it | 30 mph | 50 mph | 70 mph | 80 mph | Same as an imbalance at 0.20 m of |
|---|---|---|---|---|---|---|
| 0.05 mm | 0.1 mm | 1.8 N | 5.0 N | 9.8 N | 12.8 N | 5 g |
| 0.5 mm | 1 mm | 18.0 N | 50.0 N | 98.1 N | 128.1 N | 50 g |
| 1 mm | 2 mm | 36.0 N | 100.1 N | 196.2 N | 256.3 N | 100 g |
| 3 mm | 6 mm | 108.1 N | 300.3 N | 588.6 N | 768.8 N | 300 g |
For comparison, the balancing guide gives 7.2 N at 30 mph and 51.3 N at 80 mph for a 20 g imbalance at 0.20 m. One millimetre off centre is five times that, at every speed. Our reading: a balancing machine does not see it, because the wheel is centred on the machine, not on your hub.
What the calculation does not say is how far off centre a real wheel sits. On a lug-centric wheel, the conical or spherical seats pull it towards a position, and the real offset is smaller than the limit in the second column; we have not measured it on any car. It is an order of magnitude, to show why a few tenths of a millimetre matter, not a forecast of vibration.
How to choose a ring: two dimensions and one comparison
Onyx Forged does not recommend sizes or offsets, and does not say which ring goes on which car: the dimensions are read on the car and on the wheel in front of you.
- Measure the hub. The diameter of the spigot, the collar that the wheel fits over, clean, with a calliper.
- Find the wheel's centre bore. In the wheel maker's data, or with a calliper. UN Regulation No. 124, which covers replacement wheels, gives an example of the information a maker hands the buyer: the centre hole diameter sits next to the bolt pattern, with a column for the "centre ring marking" (Annex 10, § 1.5).
- Compare. Bore equal to the hub: no ring. Bore larger: a ring whose outside diameter is the bore and whose inside diameter is the hub. Bore smaller: the wheel does not go on, and no ring changes that.
- Read the ring's label in the right order. The sellers' pages we read give the outside diameter first, then the inside (for example "67.1 - 60.1 mm" on the listing of an aluminium ring, for a 67.1 mm bore and a 60.1 mm hub). Check which figure is which on the label you are reading.
- Check the height. Our reading, which no page we read puts a figure on: the ring must not stand prouder than the spigot, or the wheel will not sit flat on the hub face. The EUWA asks for the contact faces of wheel and hub to be clean and free of anything between them (ES 1.07); a ring that is too tall is something between them.
A worked example, with numbers chosen for the arithmetic and not taken from any car: a wheel bore of 70.0 mm and a hub of 60.0 mm. The gap is 10.0 mm across, a wall of 5.0 mm all round; the ring is 70.0 mm outside and 60.0 mm inside.
For the bolt pattern and the bore of a number of recent cars, with the basis for each figure, see our guide to PCD, bolt pattern and centre bore; it also explains how the bore differs from the PCD.
Plastic or aluminium?
| Plastic | Aluminium | |
|---|---|---|
| What the sellers' pages we read say | the most common material, described as tough and cheap (a French wheel seller names ABS) | dearer, described as suited to frequent fitting and removal (the same seller) and to heavier or more expensive cars (a Belgian tyre network) |
| What none of them gives | a maximum service temperature, or how the ring behaves near hot brakes | the same |
None of the pages we read gives a temperature or tests a ring next to the brakes, and we found no independent comparison of the two materials. We do not choose between them: ask for the ring's data sheet, with its service temperature and its height, and do not choose on a sales argument.
When a ring is not needed, needed, or impossible
| Situation | Ring | Why |
|---|---|---|
| Bore equal to the hub (original wheel, or a wheel bored for the car) | not needed | the EUWA describes hub-centric wheels as made to a reduced tolerance; Machine Design and the tyre network note that original wheels are usually hub-centric |
| Bore larger than the hub, wheel designed to be hub-centric | needed | the ring restores contact with the hub (Machine Design); the wheel's documents say whether it is required |
| Bore larger, wheel with conical or spherical seats designed to be lug-centric | as the wheel's documents say | the EUWA treats stud centring as a method in its own right (2.3); Machine Design and the tyre network still present the ring as the way to bring such a wheel closer to hub-centric support |
| Bore smaller than the hub | impossible | the wheel does not fit over the spigot; a ring can only add material inside the bore |
| A spacer between hub and wheel | the spacer must be centred on the hub, and the wheel on the spacer | see our guide to wheel spacers |
Fitting a ring: the steps that matter
If the wheel has to come off, the car is raised and then supported on axle stands, never on the jack alone, and the work is done on firm, level ground.
- Clean the spigot, the bore and the wheel's mounting face. The EUWA wants the contact faces clean and free of foreign bodies, and links the opposite to vibration, damage to the wheel and loss of torque (ES 1.07).
- Seat the ring in the wheel's bore or on the hub, as its instructions say (both are described), until it does not move. Our reading: a ring that rattles centres nothing.
- Offer the wheel onto the spigot and check that it sits flat on the hub face.
- Tighten progressively and across the wheel, "across the wheel disc and not round the wheel disc", to the torque the car maker prescribes, with a torque wrench (EUWA ES 1.02, 4.3.2). Our guides to wheel nut torque and to changing a wheel give the method.
- Check the torque again after a short run. The EUWA asks for it after 50 to 100 km following any wheel change (ES 1.07), and UN Regulation No. 124 asks the maker of a replacement wheel to tell the buyer to re-tighten after 50 km (Annex 10, § 1.4).
The MOT and the law
The MOT inspection manual has no item for hub-centric rings: the word "ring" appears in it only for the tyre retaining rings of some rims, and "hub-centric" not at all. Four items concern the fit of a wheel on its hub (MOT manual, section 5):
| Item | Defect | Category |
|---|---|---|
| 5.2.1 (b)(i) | a spigot mounted wheel hub excessively worn or damaged | major |
| 5.2.1 (b)(ii) | a spigot mounted wheel hub worn or damaged to the extent that wheel security is adversely affected | dangerous |
| 5.2.2 (c)(i) | a wheel badly distorted, or wear between wheel and hub at spigot mounting | major |
| 5.2.2 (d) | a wheel and its fixings not compatible | major |
Item 5.2.1 (a) adds a loose or missing wheel nut, bolt or stud (major; more than one: dangerous). A ring is therefore neither required nor banned by name, but wear at the spigot, the trace of a wheel that has been moving on its hub, is a major defect.
UN Regulation No. 124 defines a "pattern part" replacement wheel as one whose design, inset (offset), rim designation, fixing PCD and "spigot mounting diameter" correspond to those of the original wheel (§ 2.4.4). A wheel whose centring diameter differs from the original's does not meet that definition. Our article on new forged wheels and the MOT sets out the rest of what the test checks.
If it vibrates after fitting
A missing or wrong ring is one cause among several. In order: torque and clean faces (EUWA), balance, a buckled rim, the tyre, then the bearings. Our guide to balancing explains why an imbalance shows at some speeds and not others, and the one on alloy wheel repair what can be done about a buckle.
Frequently asked questions
Do I need hub-centric rings?
When the wheel's centre bore is larger than the hub and the wheel's documents call for hub centring, yes. When the bore matches the hub, there is nothing to fill.
Do hub-centric rings carry the weight of the car?
The sources disagree. A US wheel seller writes that they bear no weight once the nuts are tight; an engineer writing in Machine Design describes the ring as the part that carries the loads from the studs to the hub. Neither measured it. Either way, the wheel is held on by its fixings, tightened to the car maker's torque.
Can I drive without hub rings?
The wheel is then centred by its nuts or bolts alone. The EUWA describes that method for wheels designed for it; Machine Design warns that a lug-centric wheel on a car designed to be hub-centric loses the hub's support over shocks. Do not decide alone: the wheel's documents and a fitter do.
Plastic or aluminium hub rings?
The sellers' pages we read describe plastic as the common material and aluminium as dearer and suited to frequent removal, without a service temperature or a test. Ask for the ring's data sheet.
How do I know my hub size?
Measure the spigot with a calliper, clean. For some recent cars, our PCD guide gives the bore that concordant sources publish, and says where none is published.
Will hub rings stop my steering wheel shaking?
Only if the shake comes from the wheel being off centre. Balance, a buckled rim and uneven torque cause the same symptom.
Does the MOT check hub rings?
Not by name. It fails a worn spigot mounted hub, wear between wheel and hub at the spigot, a wheel and fixings that are not compatible, and loose or missing nuts or bolts.
Do I need rings with spacers?
A spacer must itself be centred on the hub, and the wheel on the spacer; our guide to wheel spacers covers it.
Do Onyx Forged wheels need hub rings?
No. Each wheel is bored to the hub of the car it is made for, so it is hub-centric without a ring or a spacer (FAQ), and the Onyx Forged design office checks the dimensions with you in writing before anything goes into production.
Made to measure: a bore that matches the hub
When you order Onyx Forged wheels, you are not asked for the centre bore, the PCD or the offset: they follow from your car. The Onyx Forged design office sets them out from your car's exact version and checks them with you before production, so the wheel is centred by the hub, as the car was designed. To find out which sizes your car lists, read what size wheels fit my car. Onyx Forged is a French brand of made-to-order forged wheels, designed to JWL/VIA standards: see Onyx Forged and the catalogue.
Sources
- EUWA, ES 1.02, Using description including the fixation (May 2011), 2.1 to 2.3 and 4.3.2.
- EUWA, ES 1.07, safety and maintenance instructions for wheels (June 2020, French edition; our translation).
- Charles C. Roberts, Jr., What's the Difference Between Lug-centric and Hub-centric Wheels?, Machine Design, 7 June 2016.
- A US tyre network's page, Hub-Centric and Lug-Centric Wheels, 3 November 2025.
- A US wheel seller's blog, What is a Hub Centric Ring? Do I need them?, 24 July 2023.
- UN Regulation No. 124, replacement wheels: § 2.4.4 and Annex 10, §§ 1.4 and 1.5.
- GOV.UK, MOT inspection manual, section 5, 5.2.1 and 5.2.2.
- A French wheel seller's page, Bagues de centrage, and a Belgian tyre network's page, Bagues de centrage (in French; our translation).
All pages were read on 15 October 2026.
The Onyx Forged design office.