Tyre and rim ABC
Here, you'll find all important pieces of information concerning tyres and rims!
Anti-lock braking system (ABS) ABS is a type of braking system that enables the wheels to maintain maximum traction at full braking pressure in the most favourable slipping range (10-30%). In order to achieve this, several thousand control impulses regulate the braking pressure to ensure that the wheels do not lock.
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 Aquaplaning occurs if the amount of water present on the road or street cannot be discharged by the drainage grooves on the tyre.
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.
Braking distance The section of the road that is covered when the brake is applied. The length of braking distance is affected by:
Brake application duration
Braking reaction time
Characteristics of the road surface (type, moisture)
Tyre condition (make, tread depth, air pressure)
Balancing Attachment of weights to the rims in order to ensure rotation of the wheel. Poorly balanced wheels place excessive stress on tyres, the wheel bearing and the suspension.
Bar Bar is a unit of measurement of air pressure.
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.
C tyre C' stands for 'commercial' and indicates tyres with increased capacity and enhanced carcass.
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”.
Damage due to incorrect installation During tyre installation, a number of points should be considered, since irreparable damage can quickly be caused if carried out incorrectly. - Never change tyres as a “do-it-yourself” procedure. Use the appropriate tools.
Use a new valve (subject to increased stress due to centrifugal force). Careful balancing.
Do not install on corroded or deformed steel / aluminium rims. The tyre does not sit correctly on the rim or is not entirely sealed.
Damage due to foreign objects Extreme caution must be taken when driving over nails, other metal objects or broken glass. The penetration of the tyre by a foreign object will cause a slow loss of air. The intrusion of moisture may also not be underestimated. This can penetrate up to the tyre belt and cause it to rust. This rust can loosen the rubber from the tyre belt, transforming the tyre into a ticking time bomb.
Drive slip control system (ASR) A vehicle's drive slip control system (abbreviated “ASR” in German) hinders the wheels from spinning on smooth or uneven surfaces. Electronic sensors are used to control the power distribution to the drive axle so that the tyres are able to grip easily and reliably during acceleration.
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!
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.
Footprint The area of the tyre that touches the ground.
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.
Tyre manufacturers have been working on this for many years, and are continuously developing new systems. These new breakdown mobility concepts make it possible to continue driving even after loss of pressure - at least to the next workshop. At what speed and to what distance may be driven depends on the system used and manufacturer.
Tyres featuring mobility properties in case of a breakdown have some more important advantages against conventional tyres or spare wheels.
No on-location wheel changes
No dirty work
No stuck wheel bolts
No search for the jack
No dangerous work on the side of the road
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 replaced with a residual profile of less than 3 mm and winter tyres with a profile depth of less than 4 mm.
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.
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.
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.
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'.
Tread The tread consists of profile negatives (grooves) and profile positives (tread blocks), which provide drainage of water or slush; on dry ground, a slick tyre without a profile offers the optimal traction.
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.
Tyre age The age of a tyre is determined by two factors. Ozone from the atmosphere penetrates the tyre rubber in small amounts and influences the sulphur compounds between the natural rubber molecules. The rubber's elasticity is diminished. Especially tyres that are stored unused become hard and brittle. This results in hairline cracks. Sun, wind, weather, and contact with oils, lubricants, and chemicals also harm tyres.
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 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 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.
Wear & tear Wear and tear depends on the tyre ageing and driving conditions. Tyre durability is determined by the driving style, loading of the vehicle, road conditions and maintenance (air pressure). For equivalent vehicle and tyre types, performance differences of several thousand kilometers are possible.
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.