Tyre and rim ABC
Here, you'll find all important information concerning tyres and rims!
Shorter braking distances than with intermittent braking
Steering control is maintained (only rotating wheels can build up lateral force)
Ability to dodge an obstacle
Braking possible in bends and corners
Stable braking behaviour on different surfaces
Shorter braking distances may only be reached in serious cases if full braking pressure is achieved by an unrelenting impact on the brake pedal. However, ABS is not a replacement for safe distances between vehicles, and unreasonable behaviour is always dangerous in spite of ABS.
All-season see all-season tyres
All-weather see all-season tyres
ABE Abbreviation for “General operating permit” (Allgemeine Betriebserlaubnis, ABE)
Abrasion / Wear When driving, braking, and pulling away, both the surface of the tyres and the surface of the street are abraded.
Ageing Different factors may influence the tyre's ageing process: moisture, UV radiation, heat and cold, etc. In order to prevent reduced performance, substances are added to the rubber compound to significantly retard the ageing process. After ten years, you should replace your old tyres with new ones nevertheless.
Aquaplaning Fenomeno di galleggiamento che si verifica quando la quantità d'acqua presente sul fondo stradale non può essere canalizzata dalla scanalature di drenaggio dei pneumatici.
Area d'impronta La superficie di contatto del pneumatico con il fondo.
Air pressure The correct air pressure is very important for the mileage and life cycle of tyres as well as for the driving safety. If tyres are underinflated, then this could cause unfavourable pressure distribution and overheating up to danger of the tyre bursting. It also increases rolling resistance, which causes increased fuel consumption. Regular inspections show that only every fourth car is being operated with sufficient air pressure.
Buying tyres If you adhere to the specifications provided by the vehicle documentation, plus the tyre size, the SI, and LI, then purchasing tyres from a specialist dealer should be easy.
Problems with driving safety occur in case of tyre mixing; thus, this is not recommended, and includes:
Combination of summer and winter tyres
Extremely different tyre ages
After installation of new tyres, a period of caution is recommended nevertheless.
1. A separating agent from the manufacturing process is still often present on the tread, which takes a few kilometres of driving to remove.
2. The requried fine-rough texture on the tyre's surface only becomes active after approx. 200 kilometres on dry road surfaces; accordingly, this may take longer on wet streets, leading to dangerous slipping.
Bead The tyre bead (the inner ring of the tyre wall) provides a secure mount for the tyre on the rim. The bead core contains one or more bead wires connected with the surrounding carcass fabric. The rubber bead filler is positioned above the bead core. This influences tyre deformations in case transverse forces are present, steering response and elasticity.
Bar Bar è l'unità di misura della pressione.
Body-to-tyre clearance Tyres and rims may not be too close to the car body or to mechanical components of the chassis such as the brakes or track rods.
Belt debonding Tyres with an air pressure that is too low produce temperatures of up to 120 °C due to the increased flexing work. Especially in the shoulder area, this may cause partial material overheating, in which case parts of the tread may separate.
Camber Camber describes the incline of a wheel or its centre line versus the vertical with regard to the road surface. If the wheel is inclined outwardly at the top, then the camber is positive (+); if the incline at the top is inward, then the wheel's camber is negative (-). This causes the tyre's footprint to be stressed on one side (inside or outside), whereby the load capacity of the tyre is reduced.
Controllo antipattinamento (ASR) Con il controllo antipattinamento (ASR) di un'autovettura si impedisce alle ruote di girare a vuoto su fondi lisci o accidentati. Grazie a sensori elettronici, la trasmissione di forza sull'asse motore viene dosata in modo tale che le ruote possano fare presa in fase di accelerazione senza problemi e in tutta sicurezza.
Carcass This is an important component of the load-bearing tyre substructure provides the tyre with durability and strength. Today, this usually consists of the artificial fabric “Rayon”.
Danni da errori nel montaggio Durante il montaggio dei pneumatici si deve prestare particolare attenzione a diversi aspetti, in quanto in questa fase non è difficile causare danni irreparabili. - La sostituzione del pneumatico non si presta al do it yourself. Utilizzo di appositi utensili.
Impiego di una nuova valvola (soggetta a sollecitazioni maggiori a causa della forza centrifuga). Equilibratura accurata.
Evitare il montaggio di pneumatici su cerchi in acciaio o alluminio corrosi o deformati. Il pneumatico non si trova nella corretta posizione rispetto al cerchio e non è più garantita la giusta tenuta.
Danni da corpi estranei Prestare la massima attenzione nel caso in cui i pneumatici passino sopra a chiodi, altri elementi di metallo o cocci di vetro. Anche un corpo estraneo, una volta penetrato nel pneumatico, può portare ad una lenta perdita di aria compressa. Non si deve favorire inoltre la penetrazione di umidità, che potrebbe poi raggiungere la cintura e farla arrugginire. A causa della ruggine, la gomma potrebbe staccarsi dalla cintura e trasformare il pneumatico in una bomba ad orologeria pronta a scoppiare.
Direction Tyres with directional tread must be installed according to a directional arrow. This offers the following advantages: Low noise emissions, increased traction under wet conditions, increased security against aquaplaning. Especially high-performance wide-based and winter tyres are becoming more and more frequently designed as directional tyres.
- EMT, ROF = Goodyear
- DSST = Dunlop
- ZP = Michelin
- SSR = Continental
- Run Flat = Bridgestone
Tyres with emergency running properties may only be used in combination with a pressure control. There are two different systems:
- Control via ABS
- Control via sensors (mounted in the rim well or in the valve)
Emergency running concepts There are different options in case of a puncture or breakdown for maintaining mobility.
1. The “classical” spare wheel, which is becoming less and less frequent.
2. The special spare for temporary use of max. 80 km/h.
3. The (collapsible) save spacer spare (like the special spare). Additional use of compressor for inflating / unfolding purposes.
4. Tyre sealant with or without compressor. (Only with compressor for cars.)
5. Self-supporting tyre (EMT, DSST). In this case, the sidewalls assume the load-bearing role of the air.
6. PAX, with modern wheel fixture on the rim with a support ring.
7. CSR with support ring
The last mentioned options (5-7) may only be used together with an air pressure check system!
Età del pneumatico L'età del pneumatico viene determinata da due fattori. L'ozono presente nell'atmosfera penetra in piccole quantità all'interno della gomma del pneumatico e influisce sui composti solfati tra le molecole di caucciù. La gomma perde così elasticità. In particolare i pneumatici conservati inutilizzati si induriscono e diventano fragili. Si formano quindi delle fessure sottilissime causate dall'invecchiamento del pneumatico. Il sole, il vento e in generale le condizioni meteorologiche, ma anche il contatto con grasso, olio e agenti chimici mettono alla dura prova i pneumatici.
Excessive ageing Every tyre ages. Physical and chemical processes diminish their functional performance. Tyres that are older than 10 years should have their quality checked by a professional dealership.
ECE identification Point 4 (tyre description) of the § 36 StVZO (Regulations Authorizing the Use of Vehicles for Road Traffic) prescribes the following tyre markings: Tyres on wheels with a top speed of more than 40 km/h must feature the following marking: Tyre size, type of tyre, load capacity, speed category and date of manufacture (or tyre renewal date). Furthermore, the "E" mark is statutory since 1st October 1998.
Electronic slip differential (LSD) An electronic slip differential is intended to brake a spinning drive gear up until a certain speed, thereby directing the extra power to the other drive wheel.
Especially in case of an electronic gas pedal, the use of an electronic slip differential is often combined with relief of torque from the motor.
The development of anti-lock braking systems (ABS) also made electronic slip differentials possible. If the brake pedal is not pressed and the rev differential of the drive gears exceeds a fixed value, then LSD ensures that the pressure is directed towards the faster-spinning wheel and that this is braked.
Electronic slip differentials are also suitable for four-wheel drive vehicles on light terrain. In case of increased strain, the brakes can get too hot.
Electronic stability program (ESP) The electronic stability program is intended to hinder the vehicle from pulling at the front or rear via targeted braking.
Function ESP only works together with ABS. If the vehicle pulls to the front in a curve or corner (understeering), then targeted braking of the rear curve-interior wheel can counteract this effect. The same effect is provided by braking the front curve-exterior wheel in case of oversteering. The speed is also reduced. For especially sporty driving, this may be deactivated on some vehicles. Second-generation ESP is capable of braking several tyres simultaneously.
Important: ESP cannot counteract physical limits. If a tight curve or corner is entered suddenly and with too much speed, the vehicle will likely skid out. In this case, braking one or more wheels will not help.
Extended Mobility Technology (EMT) Extended Mobility Technology tyres with emergency running properties. EMT tyres are able to cover, even after complete loss of air pressure, a distance of up to 80 kilometres at a speed of up to 80 km/h. This should be sufficient to reach the next specialist tyre dealer.
Equilibratura Applicazione di pesi presso il cerchio per garantire una rotazione ottimale della ruota. Ruote mal equilibrate sottopongono a sollecitazioni eccessive i pneumatici, i cuscinetti delle ruote e le sospensioni
Hump An important part of any modern tyre. This indicates the convexity surrounding the rim shoulder. Usually, two humps are present on the rim contour (wheel inner and outer side). This ensures that the tyre bead does not transfer to the rim well or base by lateral load and low air pressure.
High-speed ability In order to determine the high-speed properties, a tyre must be able to maintain its top speed (speed index) for 20 minutes on a roller dynamometer. The test increases the speed every ten minutes by 10 km/h until failure.
Inch Inch is an American unit of measurement (distance).
1 inch = 25.4 millimetres
1 Millimetre = 0.03937 inches
Imbalance Even minimal deviations in the thickness of the material or other influences have slight effects causing imbalance within the tyre. The direction of drive causes unbalancing that may be counterbalanced by adding counterweights to the rims.
Inset / Offset Inset / offset or dish(ing) refers to the distance between the wheel centre and the interior contact surface of the rim on the wheel hub, the brake drum or the brake disc. An inset or positive offset (e.g. ET +25) indicates that the rim is built further inwards (i.e. towards vehicle centre) than it is outwards.
Installation Installation of two new tyres only: The vehicle is stabilised via the rear axle. If the rear axle loses grip, then this can lead to dangerous driving conditions. For this reason, we recommend that when only two new tyres are required, that these are installed on the rear axle.
Low section tyres The section width describes the ratio of the sidewall height to the tread. The balloon tyres common in the 1920s had an aspect ratio of almost 1: 1 and has made way to the low section tyre (up to 0.25: 1).
Load capacity Every tyre must ensure a load capacity of that of the vehicle it supports and as much transmission of drive power, braking force, and lateral grip as possible, whether on dry road conditions, in case of moist or wet conditions, on snow or ice. Additional requirements:
Low roll resistance
Low noise development
Load index (LI) This multidigit number on the tyre's wall, the so-called “load index”, which provides information about the load capacity, varies according to the weight of the vehicle for tyres of the same size, e.g. small cars, mid-size limousines, transporters or vans.
Load index Abbreviated as “LI”. The load index is part of the size description of the tyre and provides information about the load-bearing capacity. In order to determine the maximum load per tyre, the identifying number must be indexed with a table. The range for cars extend from LI 50 = 190 kg to LI 124 = 1,600 kg.
A questo obiettivo stanno lavorando da anni i produttori di pneumatici, che hanno ideato nuovi sistemi anti foratura ad alta pressione. Con le nuove soluzioni per la mobilità in caso di guasto è possibile continuare la marcia anche in seguito alla perdita di pressione del pneumatico e raggiungere così l'officina più vicina. La velocità di marcia e la distanza percorribile dipendono dal sistema utilizzato e dal produttore.
I pneumatici che garantiscono la mobilità anche in caso di guasto presentano anche altri importanti vantaggi rispetto alla comune ruota di scorta.
Nessun cambio della ruota sul posto
Mai più mani sporche
Nessuna vite della ruota bloccata
Nessuna ricerca del cric
Nessun pericolo sul ciglio della strada
Mileage A tyre's service life depends on the specific vehicle, driving style, and many other factors. For vehicles with front-wheel drive, the mileage of the rear tyres may be three times as high as those on the front. Basically, the following applies: The statutory tread depth is 1.6 millimetres.
M+S M+S means “mud and snow”. These initially especially knobby or off-road tires for winter conditions and loose surfaces were presented in 1950 for the first time.
Matching Matching refers to the turning of the wheel on the rim in order to minimise radial or side run-out. For this purpose, air is let off and the tyres are each turned a quarter rotation until the best results are achieved.
Minimum profile depth For cars, trucks, and motorcycles in Europe, the minimum profile depth is 1.6 mm. These minimum dimensions must be maintained along the entire surface of the tyre. If a tyre approaches this prescribed minimum profile depth, then the braking distance increases on wet surfaces, as does the danger of aquaplaning. For tyres with a minimum profile depth of 1.6 mm, the braking distance doubles during aquaplaning versus a new tyre.
For safety reasons, summer tyres should be changed out at the latest at 2 mm, wide tyres at 3 mm, and winter tyres at 4 mm profile depth.
Oversteering Driving condition that results when the rear tyres lose grip before the front tyres: The car's rear breaks away and turns into the curve.
Off-road tyres Tyres with special properties such as impact resistance for off-road use.
Pneumatici C C sta per Commercial ed è la denominazione dei pneumatici con una capacità di carico più elevata e uno struttura inferiore rinforzata.
Permitted tyres For cars and motorcycles, vehicle documents usually listed permitted tyre makes and types by name. This meant that only the tyres listed could be used as replacements. This condition, however, was removed for cars in February 2000.
Pitch circle diameter The pitch circle (PC) diameter is one of the most important dimensions of the wheel. These four / five bolt or stud holes are arranged in a circle for attaching the wheel. Since vehicles are usually designed with different PC diameters, rims must be matched with this in mind.
Retreading Retreading is the process of applying a new tread to an older tyre. The tyres are either vulcanised in moulds (hot retreading) or heated together in autoclaves (cold retreading). Each tyre size has its own cure time.
Run-flat tyre see emergency tyre.
Retread Retread means remould or recap a tyre.
Run-flat properties (self-supporting tyre) The tyre won't jump off the rim even after loss of pressure and still allows a range of up to 80 kilometres at a speed of max. 80 km/h – sufficient to reach the next workshop or the next tyre dealer.
Rapporto d'aspetto Rapporto tra l'altezza del fianco e la larghezza del pneumatico, Esempio: un pneumatico della misura 175/70 R 13 ha una larghezza di 175 mm, un'altezza del fianco pari al 70 % della larghezza; le ultime due cifre si riferiscono alla dimensione in pollici (internazionale).
Retrofitting This refers to replacement of serial-production tyres with wider tyres and rims for a more impressive look.
Rim specifications The internationally common size indicators for rims, e.g. "7 J x 15", specify the wheel width from rim flange to rim flange; in this case, 7 inches, and the diameter, 15".
Rolling circumference The section covered by the tyre tread from any point during a wheel rotation. Thus, the rolling circumference depends on the tyre's diameter; this influences the transmission ratio as well as the speedometer drive. Standard tyres feature pneumatics with a shorter rolling circumference, and therefore a tendency for shorter transmission. Acceleration is influenced favourably, but at top speed, the rev meter could be in the red range. The smaller tyre also produces increased fast reading by the speedometer.
Tolerances of plus 1.5 % and minus 2.5 % are acceptable. In case of greater deviations, a correction of at least the speed gauge must be carried out.
Radial tyres The belt over the carcass consists (usually in multiple layers) of thin, grooved brass and rubber-coated steel wires. This is covered with a continuous band that improves high-speed ability and rotation. The belt provides the following benefits:
Improvement of driving properties
Decreased roll resistance
Low block movement on the tread
Improved driving stability - reduced wear
Good steering response and stability
Steel belts may rust. For this reason, tyres with surface injuries deep enough that moisture and air humidity as well are able to reach the steel cord should be taken off the road immediately.
Rubber compounds A tyre may consist of up to 16 different rubber compounds. The exact composition is nevertheless always kept secret by the tyre manufacturer. In order to produce a good tyre, numerous requirements are placed on rubber compounds: Low abrasion
Low roll resistance
Resistance to ageing
Radial run-out Horizontal or vertical deviation (spin imbalance) from the tyre's rotation. Only in extreme cases of radial run-out, which hardly occurs with today's products, is harmonisation neccessary. For that purpose, a special machine is used to reduce or completely correct radial run-out by milling out tread rubber.
Side run-out A lack of balance on the wheels of 10 g has the effect of 2.5 kg while driving 100 km/h due to centrifugal force. At 200 km/h, the effect is as much as 10 kg. This stresses tyres, wheel bearings, and suspension excessively. For this reason, installation should include balancing.
In case of speed-dependent vibration or a shaky steering wheel, the wheels should be rebalanced.
The sidewall is a very sensitive part of the tyre that also influences the driving properties and comfort. Damage due to incorrect use may only become apparent after months or years of use.
Several manufacturers also apply a rim protector guard to the tyre's outer wall, depending on the intended use.
Sidewall marking The sidewall provides all information about the tyre, e.g. specifications of size, type, date of manufacture, and speed class.
The tyre specifications are directly related to the sidewall. This indicates the tyre's height relative to its width. The specification "195/70" indicates that the height of the tyre's wall amounts to 70 percent of the tyre's width. This is referred to as a '70s' tyre.
Snowflake symbol The new industry standard for easy identification of tyres with tested winter characteristics. This official stamp, which is only present along with the M+S marking, provides a clear difference between M+S-marked summer and all-season tyres.
Snow chains In case of extreme snow or surface conditions that cannot be managed even with winter tyres, snow chains provide the ability to make it to the destination. Ten tips for snow chains:
1. Many wide tyre sizes do not allow chains to be mounted, due to the limited space.
2. When purchasing snow chains, make sure that the chain size is suitable for use with tyre and rim.
3. Practice chain mounting at home beforehand.
4. Pay attention to the combination of chains and alloy wheels. Most chain types may damage the rims.
5. Always mount chains on the drive wheels; in case of four-wheel drive, always mount them on the front wheels. Inquire at the vehicle manufacturer in case of doubt.
6. When driving with chains, the chainless wheels have significantly less lateral stability and will lock earlier when braking.
7. Never exceed the maximum speed of 50 km/h with chains mounted.
8. Remove chains as soon as possible on roads free of snow.
9. After use, wash off chains with hot water and allow them to dry (also for stainless steel products).
10. Repairs by the manufacturer are a good idea for expensive chains. They may also be adjusted for other tyre sizes.
Self-supporting tyres All self-supporting tyres have an enhanced substructure versus conventional tyres. This is apparent by the different carcass and belt area, enhanced sidewalls and bead zones. The advantages of the reinforced walls are the avoidance of direct and immediate contact between the rim and the inside of the tread, which may quickly destroy the tyre. These tyres may also be mounted on conventional rims. Furthermore, such tyres may be used for longer distances without pressure due to this sidewall reinforcement (at 80 km/h, this can be between 80 and 500 kilometres).
Silica The precipitated silicic acid together with a special type of rubber enables roll resistance to be reduced up to 20%, good wet-weather handling, and increased mileage.
Summer tyres A tyre for dry streets, high temperatures, relatively high to very high speeds with corresponding temperature loads, and moist or wet roads.
Spazio di frenata La distanza percorsa durante l'azionamento del pedale del freno. Sull'estensione dello spazio di frenata incidono diversi fattori:
tempi di reazione
tempi di risposta del freno
tempi di frenatura
condizioni della carreggiata (tipo, umidità)
stato dei pneumatici (prodotto, profondità del profilo, pressione di riempimento)
Sidewall This indicates the tyre's sidewall. It influences driving properties and comfort.
Sidewall height The sidewall height stands in relation to the tyre width. This means that a tyre size of "175/70 R 13 S" indicates a tyre height of 70 (70% of the tyre width). Thus, it specifies series 70 tyres. Currently, tyres of series 80 to 25 are available. For values smaller than 55, the term “wide tyre” is used.
Speed classes Also referred to as the speed index (SI), this indicates the maximum speed permitted for a tyre type. The categories are as follows:
Top speed for car tyres
ZR over 240
Top speed for C tyres
(tyres for larger vehicles)
Sipes Fine slices in the tread bar that have the effect of microscopic tyre edges. In case of winter tyres, this increases the traction during setting off and braking.
The causes of the most common defects are:
Too low air pressure
Incorrect tyre storage
Damage due to obstacles (e.g. kerbs)
Damage due to foreign objects
Damage due to high-pressure water blasters
Damage due to oil and fuel
Tubeless These products are indicated by the tyre marking 'tubeless'.
Tyre gas Nitrogen is also suitable for filling tyres. The effect is that tyres normally lose pressure at a slower rate, since the diffusion speed of nitrogen is lower compared to normal air. Tyres filled with special tyre gas may also be filled up again with normal air at any time.
Tyre size In addition to information about date of manufacture and tyre type, the markings applied to the sidewalls include size indicators: "175/70 R 13 T" indicates a tyre width of 175 mm and an aspect ratio of 0.7: 1. The R stands for 'radial design', 13 indicates the rim diameter in inches, and T is the speed index.
TPMS (Tire Pressure Monitoring Systems)
The Tire Pressure Monitoring System
A Tire Pressure Monitoring System (TPMS), or Reifendruck-Kontrollsystem (RDKS), is “…a system fitted on a vehicle which can evaluate the pressure of the tires or the variation of pressure over time and transmit corresponding information to the user while the vehicle is running” (chapter I, article 3, number 7 of the EU regulation 661/2009).
This technical monitoring of the tire pressure in everyday life is useful because many tire damages come into being due to loss of pressure which is often recognized too late by the drivers of the vehicles. A tire pressure that is too low again leads to higher fuel consumption and a weakened driving behaviour. Closely related to that is an increase of the tire temperature as well as a greater wear - and finally the tires can suddenly burst because of the tire pressure that is too low, a big safety risk for all vehicle passengers!
Tire Pressure Monitoring Systems shall minimize safety risks
TPMS have been in existence for many years, in the USA they have been mandatory for the monitoring of new vehicles for a longer period of time. Also in Europe there are regulations for TPMS, which have been established in the EU regulation 661/2009 as of July 13th, 2009:
- According to this, all new type approved vehicles of the class M1/M1G have had to be fitted with a Tire Pressure Monitoring System (TPMS) according to ECE-R 64 since November 1st, 2012.
- Further, from November 1st, 2014 all newly registered vehicles of the class M1/M1G need to be fitted with a Tire Pressure Monitoring System (TPMS) according to ECE-R 64. The named vehicle class includes vehicles used for the carriage of passengers with up to eight seats except for the driver’s seat, i.e. passenger cars, cross-country vehicles and mobile homes
In the EU regulation 661/2009 as of July 13th, 2009, the legislator does not regulate which TPMS (active/direct or passive/indirect) need to be fitted - as long as TPMS meet the ECE-R64, active/direct and passive/indirect TPMS are permitted.
reifencom supports active Tire Pressure Monitoring Systems
Our offered Tire Pressure Monitoring Sensors of the brand Schrader support active TPMS. Active TPMS consist of more components, which work together on the vehicle and thereby monitor the tire pressure:
For an active TPMS a programmed tire pressure monitoring sensor which measures the temperature of each tire in addition to the tire pressure is installed on each tire. The measured values are sent to the control unit in the vehicle (usually the on-board computer of the vehicle) when the vehicle is driving together with an individual identification of the tire pressure monitoring sensor.
Active Tire Pressure Monitoring Systems offer more safety!
Active TPMS with tire pressure monitoring sensors work more detailed because they can recognise slower loss of diffusions as well as fast pressure loss. In a few years active TPMS and tire pressure monitoring sensors will be so naturally a part of the vehicle equipment as ABS is today.
But despite the additional safety you should not forget that TPMS and tire pressure monitoring sensors can neither correct the tire pressure themselves nor give information about the tread depth of the tires - tires are the link between the vehicle and the road, and therefore it is important to check the tires regularly oneself or to have it checked in one of our branches.
Note: As a standard our complete wheel fitting is made without the tire pressure monitoring sensor.
Please keep in mind that starting from November 1st, 2014 all newly registered vehicles in the EU of the class M1/M1G (passenger cars, cross-country vehicles and mobile homes) need to have a TPMS.
If your vehicle has an active or direct TPMS with tire pressure monitoring sensors, you can order tire pressure monitoring sensors of the brand Schrader as an additional equipment for specific models of a vehicle. This possibility is shown to you, as far as it is offered by us, during the order process. Tire pressure monitoring sensors ordered by you will be fitted onto your complete wheel and programmed by us and you need to activate it on your vehicle after receipt.
Track (tyre mark) Distance between the tyre centre of the axle. May differ between the front and rear axles.
Traction Traction transforms the applied power (drive) into propulsion as a result of friction from the tyres applied to the road surface.
Treadwear indicator (TWI) The profile base of the tread features integrated treadwear indicators, and these form narrow, continuous bars on the profile at 1.6 mm tread depth. Depending on the manufacturer, the position of these bars is at the top of the sidewall and indicated by triangles, the letter combination TWI (Treadwear indicator), or small company trademarks.
Tread The tread has direct contact with the road surface and is responsible for the power transmission together with the other tyre components. It is responsible for acceleration and braking power in the direction of travel and transverse power during steering and in curves. The quality of the tread is significantly determined by the chassis (belt, carcass), bead and sidewall components, and ultimately by the design of the profile on the tread.
Tread compound The performance level of a tyre during driving is dependent on this, especially in wet or hot conditions and in terms of lateral or longitudinal forces. Mileage and noise characteristics are also determined by the tread compound.
Tyre mixing Anyone who combines makes, new and used, or summer and winter tyres is putting his life at risk: In extreme cases, uneven reactions of tyres result in uncontrollable handling.
Normally, different tyre sizes may not be installed on a single axle. The exception is in case of a puncture, when, for example, instead of another wide-base tyre, only a narrow spare tyre or spare wheel for temporary use tyre available (observe the manufacturer's instructions!).
Top speed Summer tyres: For summer tyres, the tyre's speed index must always correspond at least to the vehicle's top speed, independent of how fast the vehicle is actually driven. Winter tyres: May also be installed if their speed index is lower than the vehicle's top speed.
Valve There are two types of valves:
Rubber valves that seal the rim hole itself. Screw valves that use a sealing ring for that purpose.
Screw valves that use a sealing ring for sealing.
Valves are very sensitive to dirt, dust, and moisture. For this reason, the valve hood should always be screwed on tightly.
Valve tearing Valve tearing always leads to immediate loss of air pressure automatically.
Valve hoods The valve hoods keeps the valves free of dust, dirt and water. This significantly increases the longevity.
Water dispersion On wet surfaces, the positive blocks of the tyre must drain the water via drainage grooves. Therefore, at 80 km/h, up to 25 l of water may be channeled per second (at 100 km/h up to 31 l, at 120 km/h up to 37 l, at 140 km/h up to 43 l, and so on).
Winter tyres Besides a special tread with sipes and a greater number of negative blocks for good grip, winter tyres also consist of special natural rubber compounds so that the tread does not harden in colder conditions. Winter tyres in summer: Driving winter tyres during the summer increases the braking distance at a speed of 100 km/h by approx. 10 m, which is equal to approx. 3 car lengths.
Wet-weather handling When braking under wet conditions, tyres must be capable of absorbing increased heat energy thanks to their rubber compound.