In short. A car comes with a full-size spare, a space saver, a repair kit, run-flat tyres or nothing, and the label on the wheel or the handbook tells you which. A full-size spare identical to the road wheels is a "standard spare unit" for the UN rule, which sets no speed limit on it. A space saver is a temporary-use unit: the UN rule that governs it puts an 80 km/h (50 mph) symbol on the wheel, and in Great Britain a temporary-use spare does not make a tyre unsuitable unless you drive above 50 mph. A repair kit is sealant and a compressor: one maker limits it to a hole of 6 mm in the tread, one tyre, 80 km/h (50 mph) and 200 km (125 miles). A run-flat tyre is defined as one that can carry on at least at 50 mph for 50 miles when flat. Or you get nothing, and the breakdown service does the rest. The RAC found a spare as standard on 8 of 313 new models in 2023. If you fit new wheels, the car's spare may no longer match them: check the nuts, the label and the tyre before you need it.
What the UN rule calls a spare
UN Regulation 64 is the text that names the kinds of spare. It defines a standard spare unit as a wheel and tyre identical to the road wheel in size designations, offset and tyre structure, and it counts a steel wheel in place of an alloy one, with different nut or bolt design, as still standard. Anything else is a temporary-use spare unit, in five types (UN Regulation 64, 2.9 and 2.10):
| Kind | What it is | Limit the rule sets |
|---|---|---|
| Standard spare unit | Same wheel and tyre size, offset and structure as the road wheels | None in this rule |
| Type 1 | A temporary-use spare tyre: the narrow "space saver" | 80 km/h (50 mph) |
| Type 2 | A wheel with a different offset from the road wheel | 80 km/h (50 mph) |
| Type 3 | A tyre of a different structure | 80 km/h (50 mph) |
| Type 4 | A normal tyre on a wheel or tyre size that differs from the road wheel | 120 km/h (75 mph) |
| Type 5 | A run-flat tyre or system driven deflated in an emergency | 80 km/h (50 mph) in flat running |
The limits come from the information the rule requires in the owner's manual (6.1.2 and 6.1.2.1), and from the symbols on the wheel (5.1.4.1). The same rule says the temporary-use unit shows a distinctive colour or pattern when mounted (5.1.4.2), that only one is supplied with the car except with run-flat tyres (5.1.5), and that the manual must say the car is not to be driven with more than one fitted at a time (6.1.3) and must state the inflation pressure (6.1.4).
Two more things the rule asks for explain what you find in the boot. The unit's load capacity must be at least half the highest maximum axle load (5.1.2), and where a car stores the spare deflated, it must carry a device that inflates it to the temporary-use pressure within 10 minutes (5.1.7).
A repair kit is not in the table, because it is not a spare. It is a sealant and a compressor, and UN Regulation 64 does not mention it.
How many new cars have a spare
The RAC looked at the equipment lists of 313 new models across 28 brands and found eight, 2.6 per cent, with a spare of any kind as standard, half of those only on some versions of the model. It put the number of patrol call-outs in 2022 for a puncture with no spare at nearly 200,000, up from about 165,000 four years before (RAC Media Centre, 20 November 2023). It adds that a spare, full-size or space saver, can often still be bought as an option. An older survey by What Car? in 2018 of 251 new models found 8 per cent with a full-size spare, 30 per cent with a space saver and 55 per cent with a repair kit, the rest on run-flat tyres (What Car?, 17 May 2018).
The two surveys are five years apart and cover different models, but they point the same way: a car sold now is far more likely to have a kit than a wheel.
The space saver: what the law and the label say
A temporary-use spare tyre carries a marking, set by UN Regulation 30: the words TEMPORARY USE ONLY in capitals at least 12.7 mm high, and, for the T-type, which is designed for pressures higher than standard tyres, the legend INFLATE TO 420 kPa (60 psi) (UN Regulation 30, 2.3.5, 2.3.6 and 3.1.11). 420 kPa is 4.2 bar.
In Great Britain, regulation 27(1)(a) of the Construction and Use Regulations bars use of a tyre that is unsuitable for the use of the vehicle. Paragraph (3) says that this does not prohibit the use of a passenger car by reason only of a wheel being fitted with a temporary use spare tyre, unless the car is driven at a speed exceeding 50 mph (regulation 27). That is the legal footing for the 50 mph on the label. The regulations set a speed and no distance. A distance, if one is given, is in your handbook.
What a maker's handbook adds, in a Jaguar text: follow the warning label on the wheel; use one temporary spare only; do not exceed 80 km/h (50 mph); the pressure should be 4.2 bar (60 psi); keep the stability control on; and do not use snow chains or other traction devices on it (Jaguar, wheel changing). The text also says to fit an original-size wheel and tyre as soon as possible.
The MOT does not inspect a spare. The manual says the tester inspects the wheels and tyres fitted at the time of the inspection, and if they notice a defect on a spare wheel or tyre they tell the person presenting the car. It has no item on a space saver by name. A tyre not fitted in line with its manufacturer's sidewall instructions is a major defect, and a temporary-use tyre says TEMPORARY USE ONLY on its sidewall; we found nothing written that settles how a tester treats a space saver left on the car at the test, so take it off before the test (DVSA MOT manual, 5.2.2 and 5.2.3).
The repair kit: what it seals and what it does not
A tyre repair kit is a bottle of sealant and a compressor. Two Land Rover owner's texts we read agree on the main limits, and the first adds the last three rows (tyre repair kit, model L538). Those are one maker's limits; check yours.
| The kit | The limit in the Land Rover texts |
|---|---|
| Size and place of the hole | A puncture up to 6 mm (1/4 inch) across, within the tread area |
| Sidewall | Do not use it to seal damage to the sidewall |
| A tyre driven under-inflated | Do not use it on a tyre damaged by driving under-inflated |
| Number of tyres | One |
| Speed with a repaired tyre | Do not exceed 80 km/h (50 mph) |
| Distance | 200 km (125 miles) at most |
| The object in the tyre | Do not try to remove nails or screws |
| The sealant | It has a shelf life: the expiry date is on the bottle |
| Pressure | If the tyre will not reach the minimum pressure within the minutes the guide allows, it is not to be driven |
| The pressure warning | The sealant may cause error prompts and wrong readings from the tyre pressure monitoring system; use the kit's gauge |
| Afterwards | Tell the tyre repair centre the kit was used before the tyre is removed; replace the bottle and the hose |
The speed figure is not the same everywhere: one tyre fitter's page says a tyre sealed with a kit should be driven at no more than 30 mph and repaired professionally at the first opportunity (National Tyres). The label in your own kit rules.
The standard for tyre repairs in Britain is BS AU 159G:2013. Its scope excludes T-type temporary-use spare tyres, temporary seals, which it defines as externally inserted plugs meant to let the car be driven for a limited period until a permanent repair, the use of liquid sealants, and tyres containing sealant gel (BSI Knowledge). So a kit is outside the standard that governs a proper repair. It gets you to a fitter; it does not replace one. What the fitter can then do is the subject of slow puncture: causes and fixes.
Run-flat tyres
UN Regulation 30 defines a run-flat as a tyre that supplies the basic tyre functions at least at 80 km/h (50 mph) over 80 km (50 miles) when operating flat, which it defines as an inflation pressure between 0 and 70 kPa (UN Regulation 30, 2.3.7 and 2.32). Regulation 27(2) lets such a tyre be used deflated if it is marked as built for that. A car with run-flats also needs a warning system, which a TPMS can provide (UN Regulation 64, 5.1.6). Pirelli says manufacturers advise against repairing run-flats because their reinforced structure can hide secondary damage (Pirelli UK).
Which one deals with which puncture
| What happened | Full-size spare or space saver | Repair kit |
|---|---|---|
| A nail or screw in the tread, a small hole | Works: the wheel is changed | Works within the limits above |
| A cut or bulge in the sidewall | Works | Not to be used (Land Rover text) |
| The tyre was driven flat for some way | Works | Not to be used (Land Rover text) |
| A bent or cracked wheel | Works if you can change the wheel | Does not apply: our reading |
| Two flat tyres | Only one spare | One tyre only (Land Rover text) |
| On a motorway | Do not change it | Do not use it either: National Highways says do not attempt repairs on your vehicle |
The last row follows how to change a wheel safely: National Highways says do not attempt repairs on a motorway. A bent flange or a crack in the rim after a puncture is, in EUWA's list, a reason to replace the wheel, which is why a kit cannot be the answer there.
Bigger wheels and your spare
This is the part the pages we read leave out. UN Regulation 64 defines the vehicle type, for the spare unit, by the maximum axle loads, the characteristics of the spare, the method of drive, the suspension, the braking system, the wheel size and tyre size, and the wheel offset (2.2.1). In other words, the spare that came with your car was supplied for the wheel size, tyre size and offset the car was sold with. The regulation is about how makers supply cars; it does not tell you what to do after you change wheels. Our reading is that it shows what to check.
- The spare's status changes. If your new wheels differ in size or offset from the old, the old spare is no longer a standard spare unit in the rule's sense. Treat it as a temporary-use unit and keep to the speed on its label; if it has none, ask your fitter.
- The nuts may not fit. EUWA says all mounting parts, including the special parts for steel and alloy wheels, must fit exactly and may not be interchanged (EUWA ES 1.02, 4.3.1). McGard's advice is to keep the original nuts in the car for a steel spare when the road wheels are aluminium (McGard). If your new wheels take other nuts or bolts, the spare may need the old ones, or none will fit.
- The tool kit may not match. The locking nut adaptor and the wheel brace socket are made for the car's original nuts or bolts; if the new wheels take other fixings, they may not fit.
- The pressure warning. The pressure monitoring rule lists fitting a tyre or wheel that is incompatible with the system as one way to simulate a malfunction, so a wheel without the right sensor can set the warning lamp (MOT, TPMS and aftermarket wheels).
- A kit needs no matching wheel. It works on the tyre in place, within its limits; but sealant may upset a sensor in the wheel, as above.
The questions to ask your fitter when new wheels go on are in what size wheels fit my car and PCD, bolt pattern and centre bore.
Check what you have before you need it
- Find out which of the five your car has. Look in the boot floor, in the handbook index under "spare wheel" and "tyre repair kit", and at the wheel for the 80 km/h (50 mph) label.
- If there is a spare, check its pressure. A T-type space saver's tyre says 420 kPa (60 psi); other spares follow the label. The French tyre makers' association suggests a full-size spare at the highest recommended pressure for the car plus 0.3 bar (TNPF, in French). For a car with 2.2 bar on the front and 2.5 bar on the rear, that is 2.8 bar. That is our arithmetic on their rule, not a figure for your car.
- Check the jack, the wheel brace and the locking nut adaptor are in the car.
- If there is a kit, read the expiry date on the sealant bottle.
- Check that the nuts you carry fit the spare, especially if the spare is steel and the road wheels are alloy.
- Keep your breakdown cover details where you can find them.
Wheels from Onyx Forged
Our wheels are made to your car's specifications, centre bore included, with no spacers or spigot rings. Whether the car's own spare or locking nut adaptor still fits after a change is a question for your handbook and your tyre fitter; if you are unsure about the fixings a made-to-order wheel takes, ask customer service before fitting, not after. The Onyx Forged design office does not publish a spare-wheel pressure or a kit limit for your car: those are in your car's handbook and on the kit.
Frequently asked questions
Is a spare wheel a legal requirement in the UK?
We found no rule in the regulations or the MOT manual we read that requires a car to carry a spare wheel or a repair kit; that is a search, not a proof. The rules we found are about what you do with a temporary-use spare: regulation 27(3) allows it up to 50 mph.
How fast can you drive on a space saver?
Not above 50 mph in Great Britain, and the symbol on the wheel says 80 km/h (50 mph). Regulation 27(3) is the legal reason; UN Regulation 64 is the reason for the symbol.
How far can you drive on a space saver?
The rules we read give a speed, not a distance. Your handbook may give one. Fit a full-size wheel as soon as possible.
What pressure should a space saver have?
The T-type's tyre is marked INFLATE TO 420 kPa (60 psi). Jaguar's handbook gives 4.2 bar (60 psi) too. Check the label on yours.
Can a tyre repair kit fix a sidewall?
No. The Land Rover texts say not to use the kit on the sidewall, nor on a tyre damaged by driving under-inflated.
Can I drive on a tyre after using a repair kit?
One maker's texts say up to 80 km/h (50 mph) and 200 km (125 miles), and to tell the repair centre the kit was used before the tyre is removed. A sealed tyre is a temporary repair; BS AU 159G, the standard for permanent ones, does not cover liquid sealants.
Will the MOT fail a space saver?
The manual has no item that names one, and it does not inspect a spare in the boot. A tyre not fitted in line with its sidewall instructions is a major defect; we found nothing written on a space saver left on the car at the test. Take it off before the test.
Does my spare still work if I change my wheels?
Not necessarily. The spare was supplied for your car's original wheel size, tyre size and offset, and the nuts may not fit. Check the nuts, the label and the pressure, and ask your fitter.
Where to go next
For the steps of a change, read how to change a wheel safely; for what a fitter can repair, slow puncture: causes and fixes; for a steel spare on alloy wheels, 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
- UN Regulation No. 64, temporary-use spare unit, run-flat tyres and TPMS (02 series, 2010); UN Regulation No. 30, pneumatic tyres (Official Journal L 201, 30 July 2008).
- legislation.gov.uk, The Road Vehicles (Construction and Use) Regulations 1986, regulation 27.
- GOV.UK, MOT inspection manual, section 5.2.
- BSI Knowledge, BS AU 159G:2013 (the paid text is not read; the scope is).
- Land Rover, owner's information, Tyre repair kit; Land Rover, owner's guide, model L538; Jaguar, owner's information, Wheel changing.
- RAC Media Centre, The end of the humble spare (20 November 2023); What Car?, Which cars come with a spare wheel? (17 May 2018).
- Pirelli UK, Tyre puncture repair; National Tyres, Tyre puncture repairs.
- EUWA, ES 1.02, Using Description Including the Fixation (May 2011); McGard, installation and removal instructions.
- In French: TNPF, advice on inflation pressures.
- NIST Special Publication 811, Appendix B.9, conversion factors.
All pages were read on 15 October 2026.
The Onyx Forged design office.