Key takeaways
- A tyre repair kit is a temporary get-you-home measure, not a permanent repair: it buys you a short, slow drive to a fitter.
- Sealant kits only work on small punctures in the tread; they will not fix a sidewall, a large hole, or a tyre off the rim.
- Some sealants can coat or clog TPMS sensors, so check the label before using one.
- Using sealant can make a proper plug-and-patch repair harder or impossible, so a tyre may need replacing afterwards.
- After using a kit, drive gently to safety and arrange a proper inspection and repair as soon as possible.
To use a tyre repair kit, leave any nail in place, connect the sealant bottle to the tyre valve, empty it in, inflate the tyre with the kit's compressor and drive gently straight away so the sealant spreads. It is a get-you-home fix for a small puncture in the tread, not a repair, and it should never be used on a sidewall, a large cut or a tyre that has come off the rim.
Many new cars no longer come with a spare wheel: instead you get a small bottle of sealant and a 12-volt compressor in the boot. These kits are genuinely useful in the right situation, but they are widely misunderstood. Below is the method step by step, the limits, and the times you should not use one.
What is a tyre repair kit and how does it work?
A tyre repair kit is a get-you-home tool, usually a bottle of liquid sealant and a small air compressor. You pump the sealant into the tyre through the valve, then inflate it; the sealant coats the inside and plugs small holes as the wheel turns. It is a temporary measure to reach safety, not a lasting repair.
Crucially, it does not remove the tyre or fix it from the inside the way a professional repair does. It is designed to seal a small tread puncture just well enough to drive a short distance at reduced speed.
How to use a tyre repair kit step by step
Used correctly, a kit takes a few minutes and gets you from a quiet side road, car park or driveway to a fitter. Always read the instructions on your specific kit first, as they vary, and only use it on a small puncture in the tread. Here is the general method.
- Pull over somewhere safe and flat, switch off the engine and apply the handbrake.
- If there is an obvious object such as a nail, leave it in place: the sealant works around it.
- Shake the sealant bottle and connect it to the tyre valve as the instructions show.
- Empty the sealant into the tyre, then attach the compressor and inflate to the recommended pressure.
- Drive gently straight away for the short distance the kit specifies so the sealant spreads, then re-check the pressure.
- Keep below the maximum speed printed on the kit or the sticker that comes with it, and head for a fitter.
When should you not use a tyre repair kit?
Do not use a sealant kit on a sidewall puncture, a large hole or split, a tyre that has come off the rim, or one that is completely shredded. The sealant simply cannot bridge those, and on a sidewall it is dangerous to try. In these cases the tyre needs replacing, so call for a mobile fitter instead.
| Situation | Use a kit? |
|---|---|
| Small nail or screw in the tread | Yes, as a temporary get-you-home fix |
| Puncture in the sidewall | No, replace the tyre |
| Large cut, split or hole | No, sealant will not seal it |
| Tyre flat and off the rim | No, call for help |
| Blowout or shredded tyre | No, replace the tyre |
If the damage is in the sidewall, our sidewall damage guide explains why no repair is possible, and our guide on whether a puncture can be repaired covers the repairable zone. If there is a nail in the tread and the tyre is still holding air, read what to do about a nail in your tyre before reaching for the sealant.
The TPMS and proper-repair problem
Two limitations matter beyond the get-you-home distance. First, some sealants can coat or clog the TPMS pressure sensor mounted inside the wheel, so check whether your kit is labelled sensor-safe. Second, sealant inside a tyre can prevent a clean professional repair afterwards.
That second point catches people out. Once sealant has coated the inside of the tyre, a fitter may not be able to apply a proper plug-and-patch repair to British Standard BS AU 159, which can mean replacing a tyre that might otherwise have been saved. So treat sealant as a true last resort.
| Factor | Sealant kit | Proper repair |
|---|---|---|
| How long it lasts | Temporary, enough to reach a fitter | Permanent, done to BS AU 159 |
| Speed afterwards | Limited to the figure on the kit | Normal driving |
| TPMS sensor | Can be coated or clogged unless the kit is sensor-safe | Left clean and checked |
| Available right now | Yes, it is already in the boot | Once a fitter reaches the car |
What to do after using a kit
Once you are safe, do not treat the job as done. Drive gently, keep below the kit's stated speed limit, and get the tyre inspected and repaired or replaced as soon as you can. Tell the fitter that sealant has been used so they can clean the wheel and assess the sensor and the tyre.
If you would rather skip the sealant altogether, our mobile puncture repair comes to you across London and the surrounding counties, usually within 30 to 60 minutes, and either repairs the tyre to standard where the car is or fits a new one on the spot. No sealant, no compromise.
Kit, spare wheel or mobile callout?
If your car has no spare, it is worth knowing your options before you need them. A sealant kit is light and always in the boot but only handles small tread punctures. A spare or space-saver gets you moving for most punctures but needs changing at the roadside. A mobile callout deals with everything, including the cases the other two cannot.
- Sealant kit: best for a small tread puncture when you just need to reach a fitter.
- Space-saver spare: gets you home from most punctures but is speed-limited and temporary.
- Mobile callout: handles sidewall damage, blowouts and no-spare situations on the spot, day or night, through our emergency tyre call-out.
A sealant kit is a get-you-home fix, not a repair. We come to you with the tools and the stock to do the real one, 24 hours a day, and if sealant is already in the tyre, say so on the call so we can plan for it.
For the wider picture, see our guides on what to do with no spare tyre and the difference between a spare tyre and a space-saver.
Frequently asked questions
Only as far and as fast as the kit label allows, which is meant to get you to a fitter and no further. The seal is temporary and can weaken, so head straight for a professional inspection rather than relying on it for days.
Not always. Some sealants can coat or clog the pressure sensor inside the wheel, so check whether your kit is labelled sensor-safe before using it. If it is not, the sensor may need cleaning or replacing afterwards, which a fitter can check.
It can. Sealant coats the inside of the tyre and may prevent a clean plug-and-patch repair to British Standard BS AU 159, meaning a tyre that could have been saved might need replacing. That is why a kit should be a last resort to reach safety, not a routine fix.
No. Sealant only works on small punctures in the tread. A sidewall is too flexible and the damage too structural for sealant to hold, and driving on it is dangerous. A sidewall puncture means the tyre must be replaced, so call for a mobile fitter instead.
It is sensible to carry the kit the car came with and know how to use it, since many modern cars have no spare wheel. But remember it is a temporary fix for small tread punctures only. For anything more, a mobile fitter is the practical backup.