Various puncture treatments, or sealants, are available. They basically fall into two groups, those applied to the tyre from new and those used following a deflation. There are conflicting views from tyre manufacturers regarding the use of these sealants.
It is claimed by some that sealants used from new are dangerous. Since they seal a puncture, the car’s driver would not know that the tyre is damaged. This damage could, in reality, have rendered the tyre unfit for future use, so the driver could continue driving on a dangerous tyre.
These sealants inserted into the tyre from new work by forming a film over the inner surface of the tyre. When a penetration occurs the air pressure within the tyre forces the sealant into the injury. This type of sealant is particularly popular with operators of small off-road tractors and lawn mowers that, due to the tyre design, are susceptible to punctures from small thorns etc. Neither type of vehicle is used on the road at speed, so there is no safety issue with the use of these sealants in these cases.
The other type of sealant is injected into a tyre from a pressurised canister following a tyre deflation. The contents of the canister will both seal the leak in the tyre and re-inflate it enough to continue a journey.
It is generally accepted that puncture sealants used on roadgoing vehicles should be treated as a temporary repair only and that tyres suffering a deflation should always be checked by a qualified tyre technician for further damage. Permanent repair is often possible.
In some cases the injection of a sealant is classed as a modification to the tyre and may invalidate the tyre warranty. If in doubt, it is recommended to check with the tyre manufacturer concerned.