In short. Fitment describes where the outer face of the tyre and the rim's lip sit compared with the edge of the wing (the fender, in American English), seen from the front or from above. Flush means they line up with it, poke means they stick out beyond it, tuck means they sit under it, and stance is the name of a style that combines a very low car, tuck or near-flush wheels and often a lot of negative camber. No regulation or standard we read defines these words, so they are best expressed in millimetres: what moves the wheel is the rim width, the offset (ET), the tyre's real width and the camber angle. As for the law, the texts we read in the UK, the EU, two US states, British Columbia and New South Wales all ask for wings, fenders or mudguards that do their job, and several of them say outright that the tyre, or its tread, must stay covered: poke is where most of the legal trouble starts.
Flush, poke, tuck and stance: the words in millimetres
Take a vertical line dropped from the outer edge of the wing, above the wheel, with the car at its normal ride height and the wheels pointing straight ahead. Then measure from that line to the outermost point of the tyre's sidewall and to the rim's outer lip. A plus sign means beyond the wing, a minus sign means under it.
| Term | Tyre sidewall against the line | What people usually mean |
|---|---|---|
| Stock | inside the line, by an amount that depends on the car | the wheels the car was delivered with |
| Tuck | inside, the rim lip hidden under the wing | a low car whose wheel disappears into the arch |
| Flush | about zero, sidewall and lip in line with the wing | a common target for a road car |
| Poke | beyond the line | the tyre, and often the lip, visible past the wing |
| Stance | depends on the build | a style: very low, often tuck with negative camber, sometimes stretched tyres |
These definitions are ours, built from the way the terms are used: no standard or regulation we read defines them, so any figure you see for "moderate" or "extreme" poke is a convention, not a rule. Two points matter more than the words. First, the tyre is usually wider than the rim, so "flush with the lip" and "flush with the tyre" are not the same set-up (see below). Second, the wing is not a straight line: it curves around the wheel, so a wheel can be flush at the top of the arch and poke further forward or back. The EU rule on wheel guards looks at a whole sector of the arch, not only its highest point.
What moves the wheel in or out
Offset and width. The offset (ET) is the distance between the wheel's mounting face and the centre line of the rim. Measured from the mounting face, the outer edge of the rim sits at half the width minus the ET, and the inner edge at half the width plus the ET. Our guide to wheel offset explains the sign. Here is what that gives for a few combinations, starting from an 8J ET45 wheel chosen as an example, not taken from any particular car (rim width in inches × 25.4 = millimetres):
| Wheel | Outer edge from mounting face | Change at the wing | Inner edge from mounting face | Change at the strut |
|---|---|---|---|---|
| 8J ET45 (reference) | 56.6 mm | 0 | 146.6 mm | 0 |
| 8J ET35 (or ET45 + 10 mm spacer) | 66.6 mm | +10.0 mm | 136.6 mm | −10.0 mm (more room) |
| 8.5J ET45 | 63.0 mm | +6.4 mm | 153.0 mm | +6.4 mm (less room) |
| 8.5J ET35 | 73.0 mm | +16.4 mm | 143.0 mm | −3.6 mm |
| 9J ET35 | 79.3 mm | +22.7 mm | 149.3 mm | +2.7 mm |
| 9J ET25 | 89.3 mm | +32.7 mm | 139.3 mm | −7.3 mm |
| 10J ET20 | 107.0 mm | +50.4 mm | 147.0 mm | +0.4 mm |
This is our arithmetic, to the inner face of the rim flange (the lip itself adds its own thickness). Each millimetre taken off the ET moves the whole wheel one millimetre outwards; each extra half inch of width at the same ET adds 6.35 mm on each side. The last line shows why a wide, low-offset wheel is the usual route to poke: almost all of the extra width goes outwards. A spacer does the same as lowering the ET by its thickness; our guide to wheel spacers covers what it does to the studs and the law. The wheel offset calculator runs the same sums for your two wheels; it compares, it does not choose.
Track. Transport for NSW measures the track between the rim centre lines. Lowering the ET by 10 mm at both wheels of an axle moves each centre line 10 mm out and widens the track by 20 mm. The NSW limit of 25 mm, quoted below, therefore corresponds to 12.5 mm less ET on each side for a wheel of the same width, a figure the NSW text also gives as the limit on extra offset when non-original axle or suspension parts are fitted. The same text adds that the offset must not exceed the limits set by the vehicle manufacturer.
The tyre itself. Continental's Technical Databook lists the maximum width in operation of each tyre on each rim it may be fitted to, a width that includes the sidewall markings. For a 225/40 R 18 it gives 234 mm on a 7½J rim, 239 mm on 8J, 244 mm on 8½J and 249 mm on 9J, and states that the tyre width changes by about 5 mm for each half inch of rim width. The same book calls the distance between the flanges the "clear rim width". Our calculation: an 8J rim is 203.2 mm between the flanges, so a 225/40 R 18 on it can reach (239 − 203.2) ÷ 2 = 17.9 mm beyond each of them. We do not know the thickness of the flange itself on a given wheel, which reduces that margin, but the conclusion holds: on a typical road tyre, the sidewall usually stands outside the rim lip. A wheel whose lip is flush with the wing will, in most cases, have a tyre that pokes. A rim wider than the tyre's range (the "stretched" look) pulls the sidewall in; our guide to rim width for tyre size gives the ranges, and the one on stretched tyres explains why the practice is risky.
Camber. Camber is the tilt of the wheel seen from the front or rear (Continental UK). Negative camber tilts the top of the wheel towards the car, and too much of it wears the inner edge of the tyre (Michelin France). Tilting a wheel by an angle moves a point at height h above the contact patch inwards by h × sin(angle). Our calculation, for a 225/40 R 18 whose static radius Continental gives as 299 mm:
| Negative camber | Inward shift at hub height (299 mm) | Inward shift at 600 mm (near the top of the tyre) |
|---|---|---|
| 1° | 5.2 mm | 10.5 mm |
| 2° | 10.4 mm | 20.9 mm |
| 3° | 15.6 mm | 31.4 mm |
| 5° | 26.1 mm | 52.3 mm |
| 10° | 51.9 mm | 104.2 mm |
This is geometry only: it ignores the tyre's deformation and the way camber changes as the suspension moves. It explains why stance builds use negative camber: a few degrees pull the top of the tyre centimetres under the wing while the bottom stays put. Our guide to wheel alignment gives the maker's tolerance windows.
Ride height. Lowering a car brings the wing down over the tyre, so the same wheel looks more flush or more tucked. It also changes the camber, and Continental UK says that lifting or lowering a car requires a professional realignment. Read lowering springs and coilovers before you count on a lower car to hide a wheel.
How to measure your own car
- Park on level ground, at your normal load and tyre pressures, wheels pointing straight ahead.
- Hang a plumb line or hold a long spirit level vertically against the outer edge of the wing above the wheel centre.
- Measure horizontally from the line to the most outward point of the tyre sidewall, and then to the rim lip. Write down both, with the sign.
- Repeat forward and behind the top of the arch, roughly where the wing curves down at the front and the rear: the EU rule covers a sector from 30° in front of the wheel centre to 50° behind it.
- Check the inner side too: the gap between the tyre and the strut or spring seat is the room you would lose by going wider at the same ET.
- Compress the suspension by loading the car as you use it, and turn the steering to full lock in both directions. A wheel that clears in a straight line can foul the arch liner or the wing edge on lock. If you raise the car to look, jack it up and rest it on axle stands before you reach under it, never on the jack alone. NSW, for one, asks for no contact with the body or suspension at full lock with the suspension fully compressed. Our guide to wheels or tyres rubbing describes the three tests.
The difference between your measurement and the target tells you how far the wheel has to move. The offset table above then shows how much of it can come from ET, width or tyre. Onyx Forged does not recommend a size or an offset: the sizes your car can take are in its maker's documents, and the clearances are specific to each car.
What the law says about poke and tuck
None of the texts we read treats tuck as a problem in itself, provided nothing fouls. Poke is different: the EU/UK rule for new types, Pennsylvania, Montana (for the rear wheels) and New South Wales say in so many words that the wing, fender or flap must cover the tyre or its tread, and Great Britain and British Columbia ask for wings or mudguards that catch the spray, which a tyre standing outside them does not help.
| Country or state | Text | What it says |
|---|---|---|
| Great Britain | Construction and Use Regulations 1986, reg. 63(2) | Every car shall be equipped with wings or similar fittings "to catch, so far as practicable, mud or water thrown up by the rotation of its wheels"; reg. 63(5) lets a vehicle comply with Directive 78/549 instead |
| Great Britain, MOT | Inspection manual, 5.2.3 (f) and 6.2.1 (d)(i) | A tyre fouling a part of the vehicle is a major defect; a body with an unsafe modification, one likely to cause injury, is major |
| EU and UK, new vehicle types | Regulation (EU) No 1009/2010, Annex II, 2.1.1 | Between 30° forward and 50° rearward of the wheel centre, the width of the wheel guard "shall be at least sufficient to cover the total tyre width" |
| Pennsylvania, US | 67 Pa. Code § 175.80 (e)(1)(ix) | The inspection rejects a car when "A tire's tread extends beyond the outer edge of the wheel housing inclusive of fender flares" |
| Montana, US | MCA 61-9-407 | The rearmost wheels need fenders, splash aprons or flaps that extend "at least to each side of the width of the tire"; street rods and vehicles not originally fitted with fenders are exempt |
| British Columbia, Canada | B.C. Reg. 26/58, s. 7.06 | A vehicle not built to minimise spray to the rear "shall be equipped with mudguards and, if necessary, mudflaps" |
| New South Wales, Australia | Transport for NSW, VSI 09, rev. 5, 28 February 2019 | "The wheel and tyre must be contained within the bodywork or mudguards, including any flares, when the wheels are aligned straight"; passenger car track no more than 25 mm wider than the maker's maximum, 50 mm for off-road four-wheel drives |
The UK and the EU. Regulation 1009/2010 is a rule for new vehicle types, not a roadside test, but it shows how the wing is judged: the vehicle at the maker's declared mass in running order with one passenger in the first seating row, wheels straight ahead, and a width covering "the total tyre width". It adds that markings, decorations and protective bands or ribs on the tyre wall are not counted, and that a car with adjustable suspension height must meet the rule in the normal running position set by its maker. The UK keeps this text in its own version on legislation.gov.uk. In the EU it was repealed from 6 July 2022 by the General Safety Regulation (EU) 2019/2144, according to the EEA Joint Committee's decision 55/2022; EUR-Lex would not let us read the text that now carries the wheel guard requirements, so we do not quote it. For a car in use in Great Britain, regulation 63 asks for wings that work "so far as practicable", and the MOT fails a tyre that is fouling at the time of the test. The manual adds that marks of contact from tyre flexing or suspension movement are not a defect in themselves. Cutting or rolling a wing to make room can bring in 6.2.1 if the edge becomes likely to cause injury.
The United States. Equipment rules for cars in use are state law, and they differ. Pennsylvania's annual inspection rejects a car whose tyre tread extends beyond the wheel housing, flares included, and separately rejects a fender that is "not of a type and size used as original equipment". Montana's statute asks for fenders or flaps over the rearmost wheels that reach at least to each side of the tyre's width. We could not read California's Vehicle Code online when writing this guide, so we do not quote it. Check your own state's vehicle code and, if your state has one, its inspection manual.
Canada. The rules are provincial. British Columbia's regulation asks for mudguards and, if necessary, mudflaps on a vehicle not built to minimise spray to the rear; the version we read is the consolidation in force in February and March 2022. We did not read the other provinces' texts.
Australia. The national code for light vehicle modifications (VSB 14) would not load for us, nor would the Tasmanian, South Australian and Queensland pages. The NSW text quoted above is the one we could read; other states apply their own rules on top of the national code. Ask your state transport authority before you fit wheels that widen the track.
What none of these texts says. None of them gives a figure for how far a tyre may poke on a road car, and none defines flush, tuck or stance. If you come across a "30 mm" figure, the only 30 mm we found is in Regulation 1009/2010, and it is the minimum depth of the wing's recess over the tyre, not an allowance for the tyre to stick out.
Beyond the law: what each fitment costs
- Poke throws water and grit where the wing is meant to stop it, and puts the sidewall where a kerb reaches it first. As our guide to deep dish and concave wheels shows, a wide, low-offset wheel adds its depth on the outside.
- Flush leaves a few millimetres between tyre and wing, which compression and steering lock can use up.
- Tuck on a low car leaves little suspension travel; contact on bumps or at full lock is the usual result.
- Stance with a lot of negative camber wears the inner edge, and Michelin France notes that the camber angle is set for each car to keep the tyre as flat as possible on the road, in a straight line and in corners: a stance build gives that up for the look.
If a tyre touches the arch, the wing or the suspension after a change of wheels, have it checked before you drive the car again. If it pulls or wears unevenly, have the alignment checked.
Frequently asked questions
What does flush fitment mean?
The outer face of the tyre and the rim's lip line up with the edge of the wing, seen from the front, at normal ride height with the wheels straight. Because a tyre is usually wider than its rim, decide whether you mean the tyre or the lip; on a 225/40 R 18 on an 8J rim, the tyre can reach about 18 mm beyond each flange.
What is the difference between poke and tuck?
Poke means the tyre, and often the lip, sits outside the wing; tuck means the wheel sits under it. Lowering the offset or widening the rim pushes towards poke; a higher offset, a lower car or negative camber pushes towards tuck.
How much does 10 mm of offset change the fitment?
It moves the whole wheel 10 mm, outwards if the ET goes down and inwards if it goes up, and changes the track of that axle by 20 mm. A 10 mm spacer does the same as 10 mm less ET.
Does a wider wheel stick out more?
At the same offset, each extra half inch of width moves the outer edge out by 6.35 mm and the inner edge in by 6.35 mm, and Continental says the fitted tyre widens by about 5 mm.
Is wheel poke legal in the UK?
No text we read gives a permitted amount. Regulation 63 asks for wings that catch spray so far as practicable, the rule for new vehicle types asks the wing to cover the whole tyre width between 30° in front of and 50° behind the wheel centre, and the MOT fails a tyre fouling the car.
Is poke legal in the US, Canada and Australia?
It depends on the state or province. Pennsylvania's inspection rejects tread beyond the wheel housing, flares included; Montana asks for rear fenders or flaps at least as wide as the tyre; British Columbia asks for mudguards; New South Wales asks for the wheel and tyre to stay inside the bodywork or flares, with a track no more than 25 mm wider than the maker's maximum on a passenger car.
Do I need an alignment after changing the fitment?
After lowering or raising the car, yes: Continental UK says it requires a professional realignment. In our reading, new wheels at a different offset do not change the alignment angles themselves, but if the car pulls or wears unevenly afterwards, have it checked.
Is negative camber bad for tyres?
In excess, it wears the inner edge, as Michelin France states. Three degrees tilt the top of a 225/40 R 18 about 31 mm inwards at 600 mm above the ground, which is why stance builds use it; Michelin France adds that each car's camber is set to keep the tyre as flat as possible on the road.
Onyx Forged, a French brand, makes forged wheels to order, designed to JWL/VIA standards, at the width and offset you choose: see how to customise a set.
Sources
- legislation.gov.uk, Regulation (EU) No 1009/2010, Annex II (UK version); EEA Joint Committee Decision No 55/2022, recital 2.
- The Road Vehicles (Construction and Use) Regulations 1986, regulation 63.
- GOV.UK, MOT inspection manual: section 5, axles, wheels, tyres and suspension and section 6, body, structure and attachments.
- 67 Pa. Code § 175.80, inspection procedure; Montana Code Annotated, 61-9-407.
- British Columbia, Motor Vehicle Act Regulations, B.C. Reg. 26/58, section 7.06.
- Transport for NSW, VSI 09, Guidelines for alternative wheels and tyres, revision 5 of 28 February 2019 (copy hosted by the BMW Club NSW).
- Continental, Technical Databook Car, 4x4, Van 2015-2016; Continental UK, wheel alignment; Michelin France, alignment and balancing (in French).
All pages were read on 16 October 2026.
The Onyx Forged design office.