# car tire

Summer car tires
Low profile tires on an alloy wheel

The car tire (also called Pneu , especially in Switzerland; from Greek πνεῦμα pneuma "air, wind, breath"), mainly made of rubber or synthetic material such as Buna , forms the complete wheel of a car with the wheel disc and the rim .

In the EU, manufacturers must use a tire label on all car tires manufactured (and sold) since November 1, 2012 to provide information about their fuel consumption , wet grip and noise classification.

The abrasion of tires is currently (2018) persistent . Around 28% of primary microplastics are said to be produced by abrasion from tires.

## Types of tires according to purpose

Car tires are the link between the vehicle and the road . They significantly influence the driving behavior of a vehicle. Tires are specially designed for the nature of the ground, the temperature and the load. In Central Europe , cars mostly drive on paved roads with a surface temperature between −15 ° C and +60 ° C. The roads can have different degrees of humidity, in winter they can be covered with fresh snow, frozen snow and / or ice. Theoretically, there would be a most suitable tire for every driving situation. In racing, for example, several sets of tires with rubber of different hardness and rain tires (with tread) or slicks (without tread, for dry roads) are kept and changed. In order to cover the broadest possible spectrum under the boundary conditions of production costs and service life , the following types of tires are offered for road traffic:

### Summer tires

Profile of a summer tire

Summer tires are designed for road conditions without snow and ice . Their rubber compound does not become too soft even at high temperatures; wear is relatively low even at high speeds. In the conflict of objectives, manufacturers choose between conflicting requirements - e.g. B. the lowest possible rolling resistance with good static friction (grip in wet conditions) - a compromise .

With decreasing tread depth, the behavior in rain deteriorates , aquaplaning occurs earlier. Therefore, a 1.6 mm profile depth is legally required. The ADAC recommends a tread depth of at least 3 mm for summer tires.

### Winter tires (M + S tires)

Profile of a winter tire

Many countries have made winter tires compulsory at certain times or in certain road conditions.

In Germany, winter tires have been compulsory since December 4, 2010 in winter road conditions, that is, when ice, slippery roads and slush occur.

Snowflake symbol for winter tires, (mountain pictogram with snowflake, Alpine symbol)

Winter tires (in Switzerland winter tires ) are designed for low temperatures and winter road conditions. They have a rubber compound that is sufficiently elastic even at low temperatures to achieve sufficient power transmission (by means of interlocking with the ground). Winter tires are marked with the M + S symbol ( English Mud and Snow, German mud and snow ). The EU regulation No. 661/2009 of July 13, 2009 describes as "M + S tires" a tire whose tread profile, tread compound or structure is primarily designed to provide better driving and traction properties on snow than normal tires achieve, and announced the "more precise definition of the physical characteristics and performance requirements" by December 31, 2010 as an implementation measure.

The German StVO ( § 2 Para. 3a StVO) still refers to the EU regulation from 1992, according to which "M + S tires" are tires, "in which the profile of the tread and the structure are designed in such a way that they are ensure better driving characteristics than normal tires, especially in mud and fresh or melting snow. The profile of the tread of M + S tires is generally characterized by larger tread grooves and lugs, which are separated from each other by larger gaps than with normal tires. "(See also tire profile )

Despite these definitions, “M + S” (as of 2013) is not a protected label and can therefore also be affixed to tires that are not suitable for winter. Chinese and American tire manufacturers in particular also use this symbol on summer tires.

The label "Mountain with snow crystal" (Alpine symbol) is awarded by the American road authority NHTSA and identifies tires which, in a test, achieve at least 7 percent better traction on snow and ice than a reference tire.

From January 1, 2018, newly produced winter tires must bear the Alpine symbol on the flank if they are officially suitable for winter. M + S tires without the Alpine symbol that were produced before January 1, 2018 are still considered winter tires during the transition period until September 30, 2024.

Unlike summer tires, the profile of winter tires also has sipes, which, due to the greater number and overall length of the grip edges , enable better interlocking with loose ground, for example snow . Furthermore, winter tires generally have a tread compound that remains flexible even at low temperatures.

At low temperatures, but dry weather, tires should be driven with a tire pressure of 0.2 to 0.3  bar more than specified by the vehicle manufacturer, as the pressure increase in the tire - calculated by the tire manufacturer - is lower than at summer temperatures. On the other hand, if slush and slippery conditions prevail, the below- mentioned properties of low tire pressure are desirable.

Few off-road vehicles have automatic systems that can reduce tire pressure on slippery surfaces in order to create a larger tire contact area. If the vehicle is stuck in soft sand or the like, it may help to deflate the tires on the drive axle (s).

Unlike summer tires, winter tires are also allowed to use tires with a lower speed index - deviating from the information on the vehicle registration document . Here, too, the M + S marking is decisive, which incidentally can also have all-season tires. In Germany, a sticker with the maximum permissible speed of the tires according to the speed index must be affixed in the driver's field of vision. This marking is also mandatory in some countries that have general speed limits on motorways.

In addition to the widespread winter tires in the speed category T (up to 190 km / h), winter tires in the higher speed categories U, H and V (occasionally also W = up to 270 km / h) are available in almost all tire dimensions. On dry asphalt that is free of snow, especially at higher temperatures, you can expect slightly more abrasion from winter tires.

In spring and summer temperatures, winter tires have significantly poorer driving characteristics on dry roads compared to summer tires, e.g. B. a longer braking distance .

Regular replacement makes sense, as the rubber compound hardens over time and the adhesive properties of the tires decrease significantly, even if the tread depth is still sufficient. The ADAC recommends replacing winter tires that are more than six years old. The ÖAMTC recommends that tires only be used for 4 years.

As the tread depth decreases, the adhesive properties on snow deteriorate significantly. In Austria, winter tires must therefore have a tread depth of at least 4 mm (and an M + S mark). If the tread depth is less than 4 mm, the tire is considered a summer tire. The ADAC also recommends a 4 mm profile depth for Germany; only 1.6 mm is required by law in Germany.

#### 7 degree recommendation

For decades, the thesis was put forward in the media that winter tires had better properties than summer tires at temperatures below 7 ° C (so-called “seven-degree recommendation”). However, this statement has been refuted by tests.

Even at temperatures just above freezing point, shorter braking distances can be achieved with summer tires on both wet and dry roads than with comparable winter tires. In contrast, the braking distance of winter tires on snow and ice is significantly shorter than that of summer tires. The grip of the road surface therefore has a greater influence on the traction properties of the tires than the pure ambient temperature. Especially in combination with a dirty or dusty road surface, precipitation can significantly reduce road adhesion in all seasons.

The 7-degree recommendation (and also the “O to O rule” - “from October to Easter”) can and should remind motorists to change their tires in good time before the first snowfall and the winter cold snap . At this time, car workshops and tire dealers are overloaded in many places and an appointment must be made to change tires.

#### Studded tires

Spike sticker (Austria)

One technique that is particularly effective on ice is the use of spikes . These are steel or hard metal pins that can be attached to tires designed for this purpose. Since spikes wear the road surface considerably, they are only permitted to a limited extent or not at all in many parts of Europe . In Germany, with the exception of the small German corner , an area around Bad Reichenhall , and for certain emergency vehicles , spikes are no longer allowed.

In Austria, spikes may only be used at a restricted speed (local area: 50 km / h, open air area: 80 km / h, motorways: 100 km / h) and not in the months of June to September. Furthermore, the vehicle must be marked on the back with a special sticker.

In Switzerland , the regulations are similar to those in Austria. However, the use of spikes on motorways is not allowed.

### All season tires

Profile of an all-season tire

All-season tires (including all-weather tires ) can be used in both summer and winter. They represent a compromise between summer and winter tires. They are mainly driven in countries where there are little temperature differences between the seasons (for example Great Britain and some regions in Germany), while they are hardly common in the Alpine countries, for example . The profile of all-weather tires combines the two different groove arrangements of summer and winter tires, so that the longitudinal grooves required for higher temperatures and in wet conditions can be found as well as the tread block teeth, which provide support on slippery snow and ice.

There is no need to change tires twice a year or invest in a second wheel set. All-season tires are often used for low mileage.

The properties of all-season tires are a compromise: On snow they cannot match the properties of good winter tires; in summer they have - due to their system-related softer rubber compound - higher abrasion or tire wear and slightly higher fuel consumption. Some all-season tire types on the market have the snowflake symbol for sufficient winter traction.

In Austria, there has been a general requirement for winter tires on the drive axle for trucks over 3.5 t and for buses since winter 2006/07 .

In Germany there has been a situational winter tire requirement since December 4, 2010; it replaced a regulation that had existed since 2006 and was often criticized as vague.

Typical MT (Mud Terrain) tire profile

This group of tires is mainly used in off-road vehicles , SUVs , ATVs and UTVs . These are tires with a coarse profile, the tread of which is more or less optimized for use on unpaved roads through to difficult terrain. The selection criterion is the percentage of asphalt road / terrain and the shape of the profile. Variants are ST (Street-Terrain) with a high proportion of roads and less off-road capability, AT (All-Terrain) with roughly equal proportions of road and terrain, MT (Mud-Terrain) with a high proportion of terrain, possibly also mud, rocks and stones. Extreme variants are boggers or super swamper , which have specially coarse shovels and cleats for exclusive use in very rough terrain.

### Types of tires for trucks

When it comes to truck tires as a subtype of commercial vehicle tires, a distinction is made not only between summer and winter tires, but also according to the purpose and axle. There are different tires for drive, steering and trailer axles. The tires are also chosen differently for long-distance transport , construction site use, etc.

### Tires with run-flat properties (run-flat tires)

Section through a safety tire with a support ring on the rim

Run-flat tires have been around since the 2000s . In the event of a tire damage, these enable you to continue driving at reduced speed (at least 80 to 300 kilometers at 80 km / h). These tires are also called runflat tires, run-flat tires or RunOnFlat designated tires. Depending on the manufacturer, they are identified by the abbreviations ROF , RFT , EMT (Extended Mobility Tire), RSC (Runflat System Component), SSR (Self-Supporting Runflat Tire), ZP (Zero Pressure), DSST (Dunlop Self Supporting Technology), BSR (Bridgestone Support Ring) or PAX (Michelin Support Ring) .

The emergency running property is achieved by reinforced sidewalls or a support ring on the rim , which prevent the tire from flattening in the event of a loss of pressure or bursting and ensure sufficient transmission of steering, braking and driving forces. This effect is supported by rims with a special shape of the rim flange , the EH2 rims (Extended Hump), which prevent the damaged tire from jumping off the rim. Since drivers hardly notice a loss of pressure and are not sure about the lack of pressure, a tire pressure monitoring system is mandatory. It is no longer necessary to carry a spare wheel with you . Many armored cars are equipped with such safety tires.

## Types of tires by type

### Bias tires

Cross-ply tires were common in passenger cars until the 1960s. They have several carcass layers crossed at an angle . After that, they were replaced by radial tires and are now almost only used in agriculture, on vintage cars and on older motorcycles . They are also sometimes still used in the off-road sector because the high mobility of their treads, which is undesirable in road use, ensures better self-cleaning in mud and better adaptation to uneven surfaces. Many racing tires are built as bias tires . In terms of driving behavior, however, they have nothing in common with outdated car tires, as the carcass layers intersect at a much narrower angle. The size designation for diagonal tires, for example 6.40-15 (also in the notation 6.40–15 or 6.40–15), expresses the tire width in inches in the first value , here 6.4 inches (162.56 mm). The rear value in the tire designation indicates the required rim diameter for this tire in inches . The aspect ratio (flank height to tire width) depends on the tire shape, which is not specified. However, some width dimensions only occur in one tire shape, so that in such a case this can be derived from them. Diagonal tires are available in the tire shapes:

• Balloon with a flank height / tire width ratio of ≈ 98%, width dimension graduated to 0.25 ″,
• Super balloon with a flank height / tire width ratio of ≈ 95%, width dimension graduated to 0.10 ″,
• Low cross-section with a side height / tire width ratio of ≈ 88%, width dimension graduated to 0.50 ″, with the exception of the dimension 7.25–13,
• Super low profile with a side height / tire width ratio of ≈ 82%; For these tires, at least the tire width (at least in addition to the specification in inches) is specified in mm .

Radial tires (X technology) were developed and introduced  by Michelin in 1948 - at the suggestion of Citroën . They should achieve a longer service life than the cross-ply tires that were used up until then. In fact, the first radial tires lasted more than twice as long as diagonal tires. From 1961 it was also available from Continental in a significantly improved version.

The principle of radial tires is based on a clear separation of the functions in the tire casing. These include radially arranged carcass layers for better compression, plus stabilizing belt layers under the tread. Within the carcass, the rubberized cords lie in one or more layers radially, i.e. at right angles to the running direction. The effect is - in addition to the higher mileage - a considerable improvement compared to the cross-ply tires in terms of grip in wet conditions and in curves as well as in the running properties.

## Tire construction

In contrast to bicycle tires, today's car tires are usually tubeless.

This establishes the connection to the roadway . The tread contains the tread design (tread blocks and grooves) as well as sipes, which are designed differently depending on the summer or winter tires.
Side wall / flank
This represents the external protection of the carcass .
carcass
It is the load-bearing substructure ( frame ) of a tire. The carcass is the decisive reinforcement and is completed by a belt and tread. It consists of one or two layers of fabric that are embedded in rubber . The fabric consists of synthetic fibers , artificial silk ( rayon ) and in radial tires also from steel cords . The carcass is tensioned by the internal pressure, it holds the tire together.
It ensures the firm connection between the tire and the rim and consists of steel wires as well as the bead toe, bead sole, bead heel and the bead fillet.
Inner layer ((inner) liner)
This layer made from a special rubber compound ensures that the air does not diffuse to the outside.

## Design and development

It takes two to three years to develop a new tire until it is ready for the market. With the help of CAD systems, tire profiles are developed and z. B. built up plastically using 3D printers and processed into prototypes. In many cases, the prototypes are made entirely by hand: So-called "tire carvers" produce prototypes of future series tires by hand from a tire blank.

Since conventional air-filled tires can only be improved in details, there are development steps with completely new approaches. In March 2013, for example, the Spiegel reported about a manufacturer who had developed a new type of "grid tire" with a patented plastic grid between the rim and the tread. Several well-known manufacturers had previously presented tires without air. In March 2020, the Goodyear company presented a concept for self-regenerating tires based on the production of spider silk . Such new developments are mostly aimed at greater safety and protection against flat tires, as well as environmental protection and smoother running by avoiding the air-filled resonance body. A pneumatic tire for wheel loaders is already available from Michelin in the USA.

## Manufacturing

### New tires

The individual tire components are prefabricated in layers. This is usually done with special spraying machines or, if the layers also contain fabric or steel cord , with so-called calenders .

These layers are then applied one after the other on a winding machine, starting with the tire core. Finally, the tread compound is applied, and the green tire (green tire) is in a mold under pressure (up to 22  bar ) vulcanized . The vulcanization time and temperature (170–200 ° C for car tires) depends on the size and thickness of the tire (approx. 9–13 minutes). In this last step, the tire receives the profile, which is incorporated into the mold as a negative.

The alternative to new tires are retreaded tires . For retreading, the old running surface is roughened or peeled off, a new running surface is placed and vulcanized on . This is up to a third cheaper than making a new tire. Today, two processes are used: cold retreading and hot retreading .

Old tires

In the passenger car sector, retreaded tires play a rather subordinate role in Germany for reasons of cost. They have a market share of less than one percent for summer tires; about five percent for winter tires . They are not available as high-speed tires (identification ZR, Y, ...). This has to do with the fact that the manufacturers of retreaded tires take the aging of the casing into account and downgrade the speed index of their tires. A former V-tire becomes an H-tire, an H-tire becomes a T-tire, etc. In truck tires, on the other hand, retreaded tires have a market share of around 40 percent.

Contrary to popular belief, retreaded tires usually do not have increased rolling resistance compared to new tires; The reason for this is further developed and new technologies in the manufacture and processing of the new treads. However, retreaded tires can have defects, for example vertical and lateral runout , which have effects similar to poorly balanced wheels. As a rule, tires are only retreaded once in Germany. Retreaded tires have EEC approval and are z. B. Eligible under the current directive on the promotion of safety and the environment in road haulage companies; The grant is 80 percent of the eligible expenditure.

## Tire size, metric tire designation or marking

Example: 205 / 55R16 94V
Width, ratio, rim

A radial tire is determined by the following information:

All data are attached to the side of the car tire. The type of lettering is regulated by ECE  30 (or ECE 54 for trucks from 80 km / h). The tire size designation is made up of the width, ratio and rim diameter . The load index and speed category form the operating code.

So z. B. the inscription 185/65 R 15 85 H the following:

• 185: The nominal width of the tire unloaded at the widest point (not the tread!) Is 185 mm.
• 65: The percentage ratio of the side height to the tire width is 65%; in our example the flank height is therefore 120 mm (= 185 mm × 65%). If this number is missing, as is the case with the tire designation “155 R 15”, this ratio is 80 percent.
• R: R adiale construction of the tire carcass. A D marks the diagonal construction (according to ECE 30 this does not have to be marked).
• 15: The necessary rim diameter for this tire is 15  inches .
• 85: Specification of the load-bearing capacity in the form of the load index (LI). According to the allocation table, the LI 85 indicates a maximum permissible load of 515 kg.
• H: The speed index allows a maximum speed of 210 km / h.

### Weather marking

At the end of the lettering you will find the abbreviation M + S (for mud and snow, from the English “ m ud and s now”) for tires for winter or rough road use ; on studded tires there is an E (for ice) after the S.

### UTQG (Uniform Tire Quality Grade)

The UTQG classification characteristic indicates the performance level of a tire according to three different criteria. One differentiates:

The treadwear specification provides information about the wear behavior of the tire compared to a "standard tire". The standard tire has a treadwear value of 100. If a car tire is given the value “Treadwear 300”, it wears out three times more slowly than a standard tire. So three times the mileage can be expected. A modern everyday tire in the car sector has a treadwear value of around 250 to 400.
Traction
The traction value provides information about the adhesion properties on a wet surface. The value “AA” applies before “A” and “B” as the most adhesive, with “C” being the worst permissible value.
Temperature
The temperature code indicates how efficiently the tire can dissipate the heat generated by rolling friction and flexing . A tire with the best “A” rating is therefore significantly more temperature-sensitive than a tire of the lowest class “C”.

${\ displaystyle *}$
Tires matched by and for BMW
030908
Approval number of the tire
1
for Aston Martin and Bentley models (from Pirelli)
a
for Audi models (at Pirelli)
AO
Audi Genuine - tires tailored by and for Audi
B.
Belt tires with diagonal carcass for motorcycles (150/70 W 17 69 H)
C (commercial)
Light truck tires (185 R14 C)
CP
Tires for use on campers
DOT number
encrypted manufacturer code; Also indicates that the tire meets the requirements of the US Department of Transportation (DOT) ; the last four digits indicate the production date (DOT xxxx 3204 = 32nd week 2004).
e13
ECE test mark , tires approved according to EC regulations, 13 = country of approval (example)
E4
ECE test mark, tires approved according to ECE regulations, 4 = country of approval (example)
FR
Rim rib
FSL or MFS
Tire has a rim protection (rubber edge)
J
for Jaguar models (with Continental tires)
Country of Manufacture
MO
Mercedes Genuine - tires designed by and for Mercedes-Benz
MO Extended
Mercedes Original Run-Flat
M + S
Mud + snow tires, winter tires (but that does not say anything about suitability for winter, as there is no protected name)
N 0; N 1; N 2; N 3; N 4
Models recommended by Porsche
R, rf, XL, LT, EL, or e x tra load
reinforced Term for tires with reinforced carcass and thus increased load capacity - especially for vans
Regroovable
can be re-cut (especially for truck tires)
ROF
"Run on flat", run-flat tires
s
"Sound", tires with certificate for reduced noise emissions (gradual sales ban for tires without this label from October 1st, 2009 in Germany)
SFI
Abbreviation for "side facing inwards" inside with asymmetrical tires
SFO
Abbreviation for "side facing outwards" on asymmetrical tires
SST
Self Supporting Tire = run-flat tires (with reinforced sidewall)
T
Abbreviation "Temporary" for: emergency bikes
Tubeless
(TL) tubeless
Tube type
(TT) tubular tires
TWI
ZP
Zero Pressure (run-flat tires)
ZR
Reinforced radial tire for speeds over 240 km / h

## Others

### Production tests

Tires are checked for tire uniformity during manufacture .

### Direction of movement, inside and outside

Tire with directional binding, profile specially optimized for water drainage, 205/50 ZR 16 Uniroyal . Pointed Vs in the middle part, grooves in the pair of flanks form blunt Vs.

There are car tires with and without directional binding. In the case of tires with a directional tread pattern, there is an arrow or a note on the side wall indicating the prescribed direction of rotation. If they are mounted on the rim, they may only be mounted on one side of the vehicle and, for example, no longer crosswise exchanged together with the rim. In particular, winter tires and tires for high speeds are usually marked with a predetermined direction of travel. When viewed from above, they contain grooves drawn in V-shape, which promote the drainage of water and slush to the outside when rolling. Correctly mounted, the tip of a V hits the road first when driving forward.

If such a tire is mounted against the specified direction of rotation, this leads to deteriorated driving behavior due to a higher tendency to aquaplaning and possibly higher noise development and higher wear. In extreme cases, tire damage can occur.

It is advisable to keep the direction of rotation selected, even with non-directional tires, as the tire adapts to it through abrasion (formation of roof tile-like longitudinal profile) and tends to wear out faster when changed.

There are also tires with an inside-outside asymmetrical profile in relation to the longitudinal center of the vehicle. Due to the asymmetrical tread design, the tire tread is adapted to the specific requirements in the area of ​​the outer and inner shoulder. The outer shoulder has a great influence on cornering stability and steering response. The inner shoulder of a winter tire can provide better traction on snow thanks to the large number of engagement edges. Tires with an asymmetrical profile have a corresponding marking on the flank indicating which side should be on the outside and which on the inside.

If a tire type is both laterally asymmetrical and directional - defining the direction of rotation - there are different, chiral designs for the left and right side of the vehicle.

Tires for commercial and off-road vehicles, including construction machines, tractors and military vehicles, often have a direction of traction marking. The arrow on the side wall of the tire also shows the direction of rotation. If the direction of travel is correct, the profile can transmit more power on loose ground ( traction , i.e. better grip). Since these are usually tires for vehicles with a maximum speed of less than 80 km / h, the indication of the direction of traction is only a technical note and not a mandatory assembly instruction. Such tires have studs arranged in a V-shape, which guide mud and the like outwards when the tread is in the correct direction and thus clean it. In this case, too, the tip of the V must first reach the floor when rolling.

### Tire pressure and fuel consumption

The vehicle manufacturers indicate the recommended tire pressure for each vehicle type. It influences overall driving behavior and thus driving safety as well as fuel consumption and tire life. Usually it is given separately for the empty and the fully loaded vehicle. This information can be found in the manual or usually on a sticker in the door, in the glove compartment or on the inside of the fuel filler flap. When checking the pressure - only when the tires are cold - you should n't forget the pressure of the spare wheel .

Falling below the prescribed tire pressure leads to increased rolling resistance , spongy driving behavior, increased traction at low speeds and, in particular, to excessive heating of the tire at high speeds due to the increased flexing work . Almost all tire damage when driving on the motorway can be traced back to overheating of the tires as a result of the prescribed minimum tire pressure being significantly below the prescribed minimum.

By increasing the tire pressure by, for example, 0.2 bar above the manufacturer's recommendation, a slightly lower rolling resistance is achieved, which manifests itself in slightly lower fuel consumption. Rule of thumb: 0.2 bar more means 2 percent less consumption. In addition, by increasing the tire pressure to a certain extent, the steering accuracy, the driving stability and thus the road holding can be improved as a whole, because it makes the tire more rigid, which means that the lateral force builds up faster. However, this is only to be carried out if this deviation from the so-called "comfort tire pressure" is explicitly described and enabled in the vehicle operating instructions.

Disadvantages of this increase, on the other hand, can be a loss of driving comfort due to the higher spring stiffness of the tire and a loss of grip at low speeds due to the smaller contact surface. Fears that the profile could wear out more quickly in the middle of the tread than on the edges of the tire cannot be confirmed in practice as long as the maximum pressure of usually 3.0 bar is not exceeded. If the tire pressure is extremely low, however, the treads are more worn laterally. The area is reduced because the tire can flex less and when the inflation pressure is very high, the tread bulges outwards.

For decades, all world record runs for the lowest fuel consumption or the longest distances covered with one tank of fuel have always been driven with a tire pressure of approx. 0.5 to 1.5 bar increased.

With the same dimensions, the resistances of the brands differ by up to 20 percent (in extreme cases even up to 30 percent). Car manufacturers usually recommend increasing the tire pressure by 0.2-0.6 bar at speeds above 130–160 km / h.

### lifespan

DOT number indicating the calendar week and year of manufacture, here 10th week 2001

The life of a tire is limited. Tire rubber also ages and becomes brittle when the vehicle is stationary. The DOT number has been vulcanized onto the side wall since the 1980s . For tires manufactured from 2000 onwards, the DOT number has four digits, for example "2203" stands for the 22nd production week (calendar week) in 2003.

Tires with a three- digit DOT number without a subsequent triangle symbol were produced in the 1980s (e.g. "257" stands for the 25th week of production ( calendar week ) in 1987). Tires with a three-digit DOT number followed by a triangle symbol date from the 1990s.

To make the remaining tread depth easier to see, indicators ( TWI markings , Tread Wear Indicator ) are available, small bumps in several tread grooves that indicate a remaining tread depth of 1.6 mm. These are often marked with the letters TWI on the edge of the tire to make it easier to find. To determine the tread depth , there are various measuring methods that are applicable in some cases even in the current traffic.

Correct storage of tires can also affect their service life, as the rubber is attacked by various influences such as light and heat, but also by contact with oil, gasoline, grease and solvents, which can significantly reduce its durability.

Sawtooth formation represents a special form of tire wear , in which the individual tread blocks are worn unevenly at the front and rear.

The ADAC and its Austrian counterpart ÖAMTC recommend using tires up to the age of eight. The Swiss Automobile Club TCS warns against the use of tires that are over the age of ten.

According to a publication by the Norwegian Environment Agency from 2014, 54 percent of microplastics in the oceans come from car tire wear. 70 percent of the rubber is used for the production of car tires.

### Tire tests

The number of tire types has increased in the past.

There were shifts in demand and trends for the dimensions (diameter, width, width / height ratio). Tire buyers often base their choice on test reports and / or advice from the dealer. The ADAC tire tests are well known . There are countless testimonials on the Internet. Due to the peculiarities of tire tests, the Frankfurter Allgemeine Zeitung stopped reporting on it years ago.

### Tire gas

Sulfur hexafluoride was used as a special tire gas for filling car tires up to the year 2000 , after which it was switched to nitrogen for cost and environmental reasons. However, contrary to the claims of the providers, no verifiable advantages are known that justify tire gas or pure nitrogen in vehicle tires for road traffic compared to the usual filling with normal compressed air, which already contains 78 percent nitrogen.

With the " tread depth gauge", here a simple caliper , the tire tread can be checked

### Tire treads and aquaplaning (slippery water)

When it is wet, the profile of common tires ensures that the water between the tire and the road is displaced and drained away, so that the contact between the tire and the road surface is largely maintained and the risk of the tire floating up is reduced. How effectively aquaplaning can be avoided depends to a large extent on the tread depth and the tread design of the tire. With modern tires, one or more strong longitudinal profiles are usually selected in the middle area of ​​the tread or also asymmetrically offset, through which the water is discharged directly in the running direction. In the edge areas, the drainage effect is increased by the clearly rising transverse profile. Asymmetrically designed and arranged profile blocks ensure that the rolling noise is distributed over a broader frequency spectrum. The rolling noise, made up of several frequencies, is perceived as less loud than that of tires with identical cross-profile spacings.

### Tire change

When changing tires , other tires are fitted onto the rims .

### Wheel change

When switching between summer and winter tires, the complete wheels (tires on rims) are usually replaced. Such a wheel change can also be carried out by yourself.

Usually the wheels are swapped between the front and rear axles according to a swap strategy; Both the running direction and the tread depth must be observed. Since the rear axle is crucial for the driving stability of the vehicle, the better tires should be fitted there, regardless of which axle is driven. The best driving characteristics can be achieved with uniform tires on all wheels. Tires with different tire types and levels of wear are legally permissible.

Wheel nuts or bolts (fastening elements) must be tightened to the prescribed torque and retightened after 50–150 km of travel. Tire dealers usually remind you of this with a written notice in the vehicle and on the invoice. If the fasteners are not tightened, they can loosen. The reason for this is the settling, i.e. the slight plastic deformation on the joining surfaces. It has the effect that the frictional connection on the screw is lost, especially with wheels made of light metal, which tends to creep more than steel.

## Regulations

### European Union

In implementation of a regulation of the European Parliament and the Council of November 25, 2009, a labeling system was introduced in Germany on November 1, 2012 , which is intended to enable consumers to select the best tires in terms of fuel efficiency, wet grip and external rolling noise. The marking is designed as a pictogram and is intended to represent the fuel efficiency similar to the energy label in classes A – G, as well as the wet grip class (letters A to G) and the indication of the measured value in decibels (dB) for the external rolling noise. A marking for retreaded tires and off-road tires for commercial use and other special tires is not provided.

Noise limit values ​​according to EU regulation No. 661/2009:

Tire class Nominal width Limit values

from

2012

Limit values

from date of manufacture

November 1, 2016

C1a <= 185 mm 70 dB (A)
C1b > 185… 215 mm 71 dB (A)
C1c > 215… 245 mm 71 dB (A)
C1d > 245… 275 mm 72 dB (A)
C1e > 276 mm 74 dB (A)
C2 - 72 [73] dB (A)
C3 - Normal tires 76 dB (A)

Winter tires 78 dB (A)

73 [75] dB (A)
• Values ​​in [] brackets apply to traction tires.

### Germany

In Germany, a tire tread depth in the middle area of ​​the tread (main tread) of at least 1.6 mm is sufficient according to Section 36 Paragraph 2 Clause 4 StVZO . Nevertheless, in practice, some players in the industry encourage motorists to replace their tires before this legal limit is reached. The same influence on unnecessary tire replacement can be observed when tires are installed that are more than six years old or of different brands.

If the police detect a tread depth of less than 1.6 mm , a fine is due. If there is a specific danger, further travel can also be prohibited. In the case of traffic accidents in which a fault is established through the use of worn tires or through the use of summer tires under winter road conditions, the liability insurance can assert recourse claims against the person responsible. The own vehicle insurance can refuse a service in the fully comprehensive insurance and keep itself harmless with regard to the liability damage of the accident opponent with the vehicle owner up to a maximum amount (mostly 5000 €; see motor vehicle liability insurance ).

Since October 1, 2009, only tires with an "s" mark (particularly quiet) may be sold in Germany. This stipulation was only valid for tires up to 185 mm wide and a vehicle weight up to 3500 kg until October 1, 2010, and only up to a width of 205 mm until October 2011. This regulation has generally applied to coaches since 2009.

Since May 1, 2006, the StVO has prescribed tires that are adapted to the weather conditions: “In motor vehicles, the equipment must be adapted to the weather conditions. This included, in particular, suitable tires and antifreeze in the windshield washer system. ”In the event of a violation, a warning fee of € 20 was provided, in the event of a disability a fine of € 40 and a point entry in the central traffic register . However, “suitable tires” were not specified further by the StVO. In 2010 the regulation was classified as unconstitutional by the Higher Regional Court of Oldenburg due to a violation of the specificity requirement, whereupon the StVO was changed in the same year: Since December 4, 2010 - regardless of the season - driving on black ice, slippery snow, slush or frost Slippery ice only permitted with M + S tires (winter and all-season tires). Exceptions: agricultural and forestry vehicles, certain emergency vehicles, non-driven wheels of vehicles of classes M2, M3, N2, N3 , (heavy trucks, buses). The amount of fines has been doubled.

The 2000 guideline for the repair of pneumatic tires regulates for the Federal Republic of Germany which damage to car tires may be repaired by a specialist garage (in the case of puncture injuries in the tread area up to 6 millimeters in extent; repair ban if the tire has been treated with breakdown aid) and which repair procedures are permitted.

The wheel / tire combinations approved for a vehicle were previously entered in the vehicle registration document , the successor ( registration certificate Part I) only records one type. Which combinations are possible can be found in the certificate of conformity ( Certificate of Conformity , COC) supplied with the vehicle, inquired at the manufacturer or a testing organization (e.g. TÜV, Dekra, KÜS, GTÜ and others) or in the operating instructions for the car become. The tire and rim combinations listed in the EEC Certificate of Conformity are expressly permitted by law and do not need to be entered.

" Mixed tires " means tires with different types, namely diagonal and radial tires. Mixed tires on one axle are not permitted. Tires with summer and winter tires on one axle are not permitted; however, summer tires may be used on one axle and winter tires on the other axle. In the case of cars, either only diagonal or only radial tires may be used on the entire vehicle. There are exceptions for certain vehicles ( Section 36 StVZO).

### Austria

The Motor Vehicle Act (KFG) and the Motor Vehicle Act Implementation Ordinance (KDV) are decisive for the use of tires.

The legally prescribed minimum tread depth in Austria is:

In Austria there is the period November 1 to April 15 winter tires are mandatory , namely

• for vehicles under 3.5 tons if winter conditions prevail,
• for heavy vehicles in principle.

As winter tires only apply M + S tires or M + S & E tires ( M atsch- and S chnee- and E is-tires) not fall below the minimum tread depth for winter tires. Only they allow operation when winter tires are required or on roads that can only be driven with winter equipment. If winter tires are not required, only the minimum tread depths that apply to normal tires also apply to M + S tires or M + S & E tires. It is forbidden to operate motor vehicles with no more than 3500 kg maximum gross vehicle weight (and trailers that may be towed with them) with mixed tires, i.e. summer tires on one axle and winter tires (M + S with winter tire tread depth) on the other ( Exception: wheels that do not transfer any forces to the road). In addition, only winter tires or only M + S tires without winter tire tread depth or only summer tires may be used on an axle.

Spike tires are allowed in Austria for vehicles up to 3.5 tons, then the speed limit is 80/100 km / h outdoors / on the motorway. Spikes do not relieve the need for a chain when prescribed.

If the towing vehicle has studded tires, studded tires must also be installed on the trailer. Vehicles with spike tires must be marked with the spike sticker .

### Switzerland

The minimum tread depth according to Art. 58 Para. 4 VTS is 1.6 mm, for winter tires a minimum tread depth of 4 mm is recommended.

The term winter tires is not defined by law, so there is no obligation to equip a car with winter tires. However, it must be taken into account that the vehicle must be in an operationally safe condition regardless of the weather and the driving style must be adapted to the road conditions, otherwise the insurance company can take recourse against the driver and reduce the insurance benefit in the event of damage ( Art. 29 SVG ); in the case of an insufficient profile or inappropriate tires (summer tires in the snow), operational safety would not be met.

## Manufacturer

Since modern vehicle tires are products of a highly developed technology that are constantly being developed, there are enormous research and production costs. Small and medium-sized companies cannot afford these in the long term. In the tire industry, as in other branches of industry, a process of concentration is taking place as part of the global liberalization of trade. With a few exceptions, most of the brands offered on the global tire market belong largely or entirely to one of the five large, globally operating parent companies, which together have a global market share of almost 50%:

Besides:

There are around 1500 tire manufacturers worldwide, around 1400 of them in China. Around 1.2 billion tires are sold annually.

Most of the brands sold under the name of the parent company are offered in the upper market segment as "premium brands". In order to cover all price segments as possible, the range is supplemented with the second and third brands in the middle and lower price range. In addition, “house brands” are produced under many different names to order for service chains and tire dealers. The latter are usually well-tried models with slight design changes that have fallen out of the company's range as part of the permanent range renewal. There are also slightly different designs for tires that are specially manufactured for a certain make of car; Such tires can be recognized by additions to the tire name .

After its increased involvement in the telecommunications industry in recent years, the Pirelli Group was faced with the decision to sell its passenger car tire division to competitors, but decided to keep it because of the market value of the brand with its sporty image.

### The main tire manufacturers

Tire manufacturer Market share 2012 in% Turnover 2013 in billion euros
Bridgestone 15.3 22nd
Michelin 14th 20.2
Goodyear 10 14.2
Continental 5.8 10
Sumitomo 4.2 4.8
Pirelli 4.1 6.1
Hankook 3.4 5
Yokohama 3 3.4
Maxxis 2.5 3.2

## Trivia

The Lego Group is by far the world's largest manufacturer of tires - for toys - according to its own statements : In 2016 the company produced over 730 million pieces, around four times as many as the largest "regular" tire manufacturer Bridgestone.

One of the most important ways of spreading invasive mosquitoes such as the Asian tiger mosquito and the Asian bush mosquito is the used tire trade. With the tires, eggs from Asia are transported by cargo ship to Europe, where the tires u. a. used to produce whisper concrete.

## literature

• Jörnsen Reimpell, Peter Sponagel: Tires and Wheels. In: Jörnsen Reimpell (Ed.): Fahrwerktechnik. Vogel, Würzburg 1988, ISBN 3-8023-0737-2 .

Commons : Car Tires  - Collection of pictures, videos and audio files
Wiktionary: car tires  - explanations of meanings, word origins, synonyms, translations

## Individual evidence

1. a b Tires: The right tread depth - for the best grip. In: adac.de. ADAC , April 26, 2019, accessed on August 24, 2019 .
2. Stiftung Warentest on the M + S mark In: test 12/2010, page 76.
3. Beware of cheap brands with M + S symbols. In: focus.de , December 2, 2010.
4. Road Traffic Licensing Regulations (StVZO), Section 36 Tires and Treads, Section 4 In: gesetze-im-Internet.de .
5. Winter tires in summer. ADAC, accessed on February 4, 2018 : "... the braking distance from 100 km / h is extended by up to 16 meters."
6. All about the tire. ADAC, accessed on February 4, 2018 : "Tires age, even if they are not used! The safety of old tires decreases significantly. Therefore do not use tires that are more than 8 years old. "
7. All about the tire. In: oeamtc.at. Austrian Automobile, Motorcycle and Touring Club , accessed on February 4, 2018 : "Only four identical tires that have not been in use for more than four years should be used."
8. ^ Christian Wüst: Automobile - Ice-cold dizziness . In: Der Spiegel . No. 42 , 2005 ( online ).
9. ^ Albert Königshausen and Peter Weyer: Winter tires: dispute about security. In: stern.de. Der Stern , November 30, 2005, accessed May 28, 2012 .
10. Studded tires. In: HELP.gv.at . Retrieved February 4, 2018 .
11. Marktjagd: Tire Change - The Right Tire for Every Weather ( Memento of the original from October 30, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , marktjagd.de, October 30, 2013
12. Stiftung Warentest: All-season tires - no compromises. In: test.de , October 19, 2012.
13. Dunlop Self Supporting Technology (last accessed January 25, 2015)
14. The run-flat technology. In: kfztech.de . Retrieved August 27, 2008.
15. ^ A b Max Bohner, Wolfgang Keil, Siegfried Leyer, Wolfram Pichler, Wolfgang Saier, Harro Schmidt, Paul Siegmayer, Heinz Zwickel: Book of tables for motor vehicle technology. Tables, formulas, overviews, standards. Mathematics, basic knowledge, specialist knowledge of automotive technology, materials science, drawing, standard parts (= European reference book series for automotive technology .). 10th edition. Verlag Europa-Lehrmittel, Nourney, Vollmer GmbH & Co., Haan-Gruiten 1994, ISBN 3-8085-2070-1 , p. 227 (Head of the working group and editing: Rolf Gscheidle).
16. auto motor und sport 05/1961, pp. 29–32.
17. From rubber to tires in the age of double-A. In: motor-talk.de , July 5, 2012.
18. Julia Spurzem: Hand-carved tires In: spiegel.de . Spiegel Online , October 3, 2012.
19. Pinkstone, Joe: Goodyear unveils a self-regenerating TIRE that uses a capsule of biodegradable liquid 'inspired by spider silk' in the center of the wheel to 'recharge' the tread. In: www.dailymail.co.uk. March 3, 2020, accessed on March 3, 2020 .
20. Jürgen Pander: New tire technology: the air has to go. In: spiegel.de . Spiegel Online , March 26, 2013.
21. Second chance on the asphalt. In: Abendblatt.de .
22. MID: Passenger Cars: Ban on selling noise tires. In: Focus Online . September 9, 2009, accessed October 14, 2018 .
23. ECE test mark and tire age ( Memento from February 12, 2007 in the Internet Archive )
24. Archive link ( Memento from November 13, 2013 in the Internet Archive )
25. Topic tire storage
26. Aging in car tires. In: adac.de. Retrieved July 22, 2017 .
27. Tim Neumann: Old tires are a safety risk: after eight years at the latest, you need new ones. In: auto-service.de. March 21, 2014, accessed July 22, 2017 .
28. FAQ tires. In: tcs.ch. Retrieved July 22, 2017 .
29. Peter Sundt, Per-Erik Schulze and Frode Syversen: Sources of microplastics-pollution to the marine environment. (PDF) 2014; Table 8-1 “Summary of emission estimates for Norwegian sources to microplastic pollution” (p. 88).
30. The Rubber Apocalypse. In: zeit.de , November 10, 2013, accessed on November 26, 2017.