Who repairs car tires?
How does the nail get into the tire and who gets it out again?
Holes in tires are rare, but annoying. Can a tire be patched or repaired at all? Is it allowed? How does it work? Here’s what the pros have to say.
What’s that hissing? Many people have certainly asked themselves this question. Often after parking the car. Usually the hissing is accompanied by an unknown movement of the stationary car: it sinks. The hissing volatile inflation pressure causes the tire to slump. The clearly pulse-accelerating variant is the loss of tire pressure while driving with sudden unstable cornering. The moderately dynamic variant is the warning from the tire pressure monitoring system: this lowers the pulse, but does not change the situation. In all cases, the culprit is quickly found: Screws, nails or other pieces of metal have penetrated the thick tire rubber, punctured the carcass and finally the sealing layer of the tire. What to do? Puncture spray purely or by means of rubber sausages again tightly get? Can it be repaired or does the tire have to be completely replaced?
Is repairing allowed at all?
Repairing tires is not forbidden according to § 36 of the German Road Traffic Licensing Regulations (Straßenverkehrszulassungsordnung). The guidelines for the repair of pneumatic tires and for the assessment of tire damage from 2001 are applied. These guidelines allow the repair and use of puncture repair equipment under certain conditions: It depends on the tire structure, where the damage is on the tire and how long the damage has been acute.
Michael Schwämmlein, Technical Director of the German Tire Trade and Vulcanizing Trade Association (BRV). (BRV) is important here: “A tire repair should always be carried out by a specialist company. We therefore recommend contacting a master company of the vulcanizing/tyre mechanic trade or a master automotive company with the appropriate authorization to practice in the tire repair sector.”
What damage can be repaired?
The guideline for assessing tire damage distinguishes between two damage categories. On the one hand, superficial tire damage: pure rubber injuries to the tread and sidewalls that do not involve a loss of pressure and do not expose any strength members, such as threads or wires. Depending on the type of tire, these can be tolerated within certain limits without repair. This includes small cracks or cuts that do not run around the entire circumference and from which no cords are protruding. Likewise, aging cracks, not deeper than one millimeter, are considered superficial damage on passenger car tires.
Here, by the way, there is nothing more to be gained in terms of repair.
On the other hand, safety-relevant tire damage: anything that causes a loss of pressure or changes the structure and properties of the tire. The latter which has to do with major damage to the tread, sidewall or bead area. Basically, the professional can repair almost any damage using various techniques and materials, if the tire does not have other damage due to the loss of pressure.
“The main component of the expert’s appraisal, in addition to assessing the visible damage for its repairability, is the identification of damage that indicates damage to the structure of the tire. These can be, for example, bulges and dents in the tire sidewall or wrinkling and discoloration on the inside of the tire in the flexing zone. Both indicate that the tire has been overloaded while driving with insufficient air pressure. No more repairs should be made here,” adds Michael Schwämmlein from BRV.
What does roadside assistance mean?
According to the guideline, the term “breakdown assistance” refers to temporary emergency aids that enable a trip to the workshop to change the tire. In other words, aids such as puncture spray, sealing milk with compressors or sealing cords inserted from the outside by awl. This is by definition not a permanent repair and after their use, a professional repair – even if possible – is no longer allowed.
This can’t be anything permanent: Sealing cords pressed in from the outside look like a temporary fix from the inside.
“Liquid or gel-like puncture sealants make it difficult to inspect the tire for structural damage, are sometimes difficult to remove and, in the case of certain types of damage, can create residues in the strength members that cannot be completely removed during a repair,” says Michael Schwämmlein of BRV, explaining the exclusion of tires treated in this way from professional repair.
What does repair mean?
The guideline defines a repair as the complete filling of the hole channel with raw rubber up to the sealing layer inside the tire and the use of a patch applied from the inside. Both must be finally treated by hot or warm vulcanization. Alternatively, pre-vulcanized rubber bodies and the so-called combination repair bodies are also permitted. In both cases, the materials used must be matched to the size and type of damage. Either way: The tire must be taken off the rim and inspected by a specialist.
Self-sealing tires on cars are basically repairable, but the additional sealing layer (orange) complicates existing repair methods: the layer must be removed over a large area around the spot.
“Currently a big topic among specialist workshops is the repair of self-sealing tires and the so-called acoustic tires. Due to the additional, semi-viscous sealing layer or the insulating foam, common procedures have to be adapted. The sealant must be partially removed for repair in some procedures, and the foam must also be partially removed for repair. This reduces the self-sealing and sound-insulating properties in this area,” Michael Schwämmlein emphasizes current challenges with new types of tires.
Even semi-slicks and other UHP tires for fast supersports are not excluded from repair.
What else is there to consider?
Although the directive opens up a wide range of possibilities, the repair shops or chains carrying out the repairs have their own regulations. For example, Euromaster restricts repairs with combination bodies if the hole is closer than six millimeters to the transition between tread and sidewall. Also, Euromaster does not repair tires with a speed index higher than T, i.e. 210 km/h.
In principle, there is no legal restriction to a certain speed category for a tire repair, however, the repairer is liable for performed repair and causal consequential damage caused by the tire repair.
Why is there air in the tire?
Air in tires is basically a compromise that is over 130 years old. Solid rubber tires do not provide the comfort needed – then and now, and they are heavier and more complex to install. Today, all tire manufacturers are looking for a better solution – without air. Michelin is already quite far along with the Uptis for passenger cars and has been gathering experience with the Tweel tire for years. Bridgestone also wants to let the air out of the tire forever with the Airless Tire.
Tires that manage without air have been the dream of tire manufacturers ever since Goodyear accidentally invented vulcanization. Michelin’s Uptis is announced for 2024.
Very important – they may be expensive and I check them all the time.
Not so important – cheap floppy tires will do.
To repair tires or not? The conversations with Michael Schwämmlein from BRV suggest: From a professional in any case. Whether you will find them there, where mainly tires are sold. Questionable.
The many technical possibilities of vulcanizers mean that almost all damage can be repaired, and the habit of thinking first of the dealer you trust when it comes to tires may limit you.
Puncture sprays or puncture repair are per se not a means of repair, otherwise they would be called repair spray. On the contrary, their use prevents having damage professionally repaired.
New tire designs with self-sealing or sound-absorbing layers are a challenge for the repairer – for the tire recycler, by the way. Speaking of the environment: With regard to the sustainability of mobility, every professionally repaired tire is a gain. The repaired tire does not have to be disposed of – only when it is really broken.