A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Tyre ABC - The Big Encyclopaedia with Details

• A
  • Abbreviations and Meanings
  • Rolling Noise
  • Tyre Circumference
  • All Terrain Tyres (AT)
  • All Season Tyres
  • All Wheel Drive (AWD)
  • Aquaplaning
  • Asymmetric Tyres
  • Discontinued Model
• B
  • Braking Distance
• C
  • CrossClimate
  • C Tyres
  • CP Tyres
• D
  • Dimension
  • Double Marking
  • DOT Number
• E
  • EAN – European Article Number
  • ECE Mark
  • EU Tyre Label
  • Extra Load Tyres (XL)
• F
  • Rim Lip (FR) / Rim Protection Strip (FSL)
  • Fuel Saver (FS)
• G
  • All Year Tyres
  • Speed Index
  • Off-road Tyres
  • Noise Emission
  • Rubber Compound
• H
  • Tyre Homologation
  • High-Speed Tyres
• I
  • TWI Indicator
• J
• K
  • Carcass
  • Comfort Tyres
  • Contact Patch / Tyre Contact Area
• L
  • Mileage
  • Sipes
  • Air Pressure
• M
  • MS Marking
  • Minimum Tread Depth
  • Swiss MOT Inspection
• N
  • Wet Grip
  • Negative Camber
  • Runflat Emergency Tyres
• O
  • Off-road Tyres
  • Original Equipment Tyres / Original Equipment (OE)
• P
  • Tread Depth
  • Tyres
• Q
  • Aspect Ratio
• R
  • Radial Tyres
  • Tyre Test
  • Tyre Rotation
  • Tyre Wear
  • RunFlat Technology
  • Rolling Resistance
  • Tyre Pressure
  • Tyre Pressure Monitoring System (TPMS)
  • Directional Tyres
• S
  • Summer Tyres
  • Spikes
  • Track width
  • Symmetric Tyres
• T
  • Load Index
  • Traction
  • TWI Tread Wear Indicator
• U
  • Ultra High Performance Tyres
• V
  • Valve
  • Vulcanisation
• W
  • Winter Tyres
  • Balancing Weights
• X
• Y
• Z
  • Inch

A

Abbreviations and Meanings

Tyre Noise

Tyre noise describes how loud a tyre is during driving. A low value means more driving comfort and less environmental noise pollution. The EU tyre label indicates tyre noise in decibels. Particularly quiet tyres are advantageous in the city and on long journeys.

Tyre Circumference

Tyre circumference refers to the distance a tyre covers in one complete revolution. It depends on the tyre width, the aspect ratio, and the wheel diameter.

Why is tyre circumference important?

• It influences the speedometer reading: If the tyre circumference is too large, the speedometer will show less than the actual speed.
• When changing wheel or tyre sizes, the tyre circumference must remain within a legally specified tolerance range to ensure vehicle registration and safety.
• The correct tyre circumference is essential for registration in Switzerland (MFK) and for tyre or wheel approvals.

Tolerance Range

• As a rule, a deviation of ±2% to 3% from the original tyre circumference is permitted
• Anything beyond that requires special approval or will not be permitted

Calculation

The tyre circumference can be calculated using special tables, online calculators, or directly from the tyre dimensions:

• Example: 225/45 R17 → Tyre circumference approx. 1,986 mm

Conclusion: Tyre circumference is crucial for the speedometer, safety, and registration. It should always be checked when changing to different dimensions.

All Terrain Tyres (AT)

All Terrain tyres – often called AT tyres – are a mix of road tyres and off-road tyres. They are developed for off-road vehicles, pickups, and SUVs that are driven both on asphalt and off-road.

All Season Tyres

All Season tyres, also known as all-weather tyres, combine the characteristics of summer tyres and winter tyres in one product. They are intended for drivers who want to use a single set of tyres all year round and do not want to change tyres seasonally.

All Wheel Drive (AWD)

All Wheel Drive means four-wheel drive. Vehicles with All Wheel Drive distribute engine power to all four wheels. This improves traction on wet roads, in snow, and off-road.

Aquaplaning

Aquaplaning occurs when water is no longer displaced quickly enough from the tyre tread and the tyre floats on the water surface. This causes the vehicle to lose ground contact and become difficult to steer or brake. Sufficient tread depth, correctly chosen tyre pressure, and an appropriate speed in the rain are crucial.

Asymmetric Tyres

Asymmetric tyres have a special tread pattern composed of two different zones: an outer side and an inner side. This design ensures an optimal combination of driving stability, wet grip safety, and comfort.

Discontinued Model

A discontinued model is a tyre that is no longer produced new by the manufacturer. These are usually older tyre patterns that are replaced by successor models with modern technology.

B

Braking Distance

Braking distance is the distance a vehicle travels from the moment braking is initiated until it comes to a complete stop. Tyre quality has a significant impact here.

Influencing Factors:

• Tread pattern and tread depth
• Rubber compound (summer, winter, all-season tyres)
• Tyre pressure
• Speed and road surface

C

CrossClimate

CrossClimate is a product line from Michelin and represents all-season tyres. These tyres are designed to be driven in both summer and winter. They save you the hassle of changing tyres, but are usually a compromise compared to dedicated summer or winter tyres.

C Tyres

C tyres are specially developed for vans, light commercial vehicles, and pickups.

• The "C" stands for Commercial
• Reinforced carcass and higher load capacity
• Designed for heavy loads and continuous strain
• Example: 195/70 R15

CP Tyres

CP tyres are specially developed for motorhomes.

• Abbreviation "CP" = Camping Pneus
• Reinforced sidewalls → high stability when stationary and under load
• Adapted for long journeys with heavy loads

D

Dimension

The tyre dimension describes the width, height, and wheel size of a tyre.

• Example: 225/45 R17
• 225 = Tyre width in mm
• 45 = Aspect ratio (height in % of width)
• R = Radial construction
• 17 = Wheel diameter in inches

Dual Marking

Dual marking on tyres means that a tyre is approved for two different speed ratings or two different load capacities. This marking is often found on SUVs, vans, or high-performance vehicles.

An example would be a tyre with the marking 245 45 R19 102 Y (100 W).

• The first value (102 Y) describes the standard approval: load index 102 and speed index Y (up to 300 km/h).
• In parentheses is a second approval (100 W), which states that the tyre is also approved for load index 100 and speed index W (up to 270 km/h).

Characteristics

• Manufacturers use dual marking to approve tyres for multiple vehicle types.
• Often found in combination with reinforced tyres (XL) or special homologations.

Advantages

• More flexibility in tyre selection
• Broader compatibility with different vehicles
• Facilitates approval for vehicles with different requirements

Disadvantages

• Can be confusing for laypeople
• Incorrect selection can lead to problems with the MFK (Roadworthiness Test) or manufacturer approval

DOT Number

The DOT number is embossed on the tyre sidewall and indicates the manufacturing date.

• Consists of 4 digits, e.g., 2324 = 23rd calendar week of 2024
• Important when buying tyres, as older tyres, although unused, can harden

Note for Switzerland: Tyres are considered "new" for up to 3 years after manufacture.

E

EAN – European Article Number

The EAN number is the barcode of a tyre and is used for unique identification in trade.

• Helpful for ordering and logistics
• Each manufacturer assigns its own EAN codes per size and model

ECE Approval Mark

The ECE approval mark is an international marking that confirms a tyre complies with the regulations of the United Nations Economic Commission for Europe (UNECE). In Switzerland and throughout the EU, only tyres with a valid ECE approval mark may be sold and used.

Marking

• On the tyre sidewall, there is a circle with the letter E or e and a number.
• The number indicates the country in which the approval was granted (e.g., E1 = Germany, E4 = Netherlands).
• Example: E4 027550

EU Tyre Label

Mandatory in the EU since 2012. It rates tyres according to three criteria:

1. Rolling resistance (fuel efficiency)
2. Wet grip (braking distance in the rain)
3. Noise emissions (external noise in decibels, 1–3 sound waves)

Extra Load Tyres (XL)

XL tyres have a reinforced carcass and can carry more weight at higher tyre pressures.

• Marking "XL" or "Reinforced" on the sidewall
• Suitable for SUVs, vans, transporters, and vehicles with high payload capacity

Advantages: Higher load capacity, more stability, better performance at high speeds
Disadvantages: Harsher ride feel, higher price

F

Wheel Rib (FR) / Wheel Protection Lip (FSL)

Marking for tyres with a protective rib at the transition to the wheel, to protect it from scratches or damage

Fuel Saver (FS)

Tyres with an optimised rubber compound or special construction for low rolling resistance.

• Advantage: lower fuel consumption and less CO₂ emissions

G

All Season Tyres

All Season tyres – also known as All Season tyres – combine the properties of summer and winter tyres.

• Practical for regions with mild climates
• No seasonal tyre change required
• Identifiable by the M+S symbol and often additionally by the 3PMSF (snowflake symbol)

Conclusion: Ideal for low-mileage drivers and cities with mild winters. In regions with heavy snowfall, winter tyres are superior.

Speed Index

The speed index indicates the maximum speed for which a tyre is approved. It is represented on the tyre sidewall by a letter, for example H, V, W, or Y. The index is legally required and must correspond to at least the maximum speed of the vehicle.

Example
In the marking 225 45 R17 91V, the "V" stands for a maximum permissible speed of 240 km/h.

Important Notes

• The index may be chosen to be higher than prescribed, but not lower
• For winter tyres, a lower index is permitted in many countries, including Switzerland.
• The speed index and load index are crucial for safety together

Table of common speed indices

Off-Road Tyres

Off-road tyres are specifically designed for use off paved roads. They have a particularly coarse tread with large tread blocks and deep grooves, which ensures maximum traction on gravel, sand, mud, and snow.

Characteristics

• Very robustly constructed carcass, often with reinforced sidewalls
• Coarse tread pattern for better grip on loose surfaces
• Higher noise level and rolling resistance on asphalt
• Often available as All Terrain (AT) or Mud Terrain (MT) versions

Advantages

• Optimal traction off-road
• High stability and resistance to stones or sharp edges
• Suitable for adventures, off-road tours, and agricultural use

Disadvantages

• Louder and less comfortable on normal roads
• Longer braking distances on asphalt
• Higher fuel consumption due to greater rolling resistance

Conclusion: Off-road tyres are the right choice for drivers who regularly travel off paved roads. For everyday use on asphalt, All Season or pure road tyres are often the better choice.

Noise Emission

Noise emission describes the external loudness of a tyre, measured in decibels (dB).

• Part of the EU tyre label
• Symbolised by 1–3 sound waves:
• 1 wave = quiet
• 3 waves = loud

Conclusion: The lower the noise emission, the more pleasant for the driver and the environment.

Rubber Compound

The rubber compound is the material composition of a tyre.

• Summer tyres: harder compound → stable in heat
• Winter tyres: softer compound → elastic in cold
• All Season tyres: compromise between the two

Conclusion: The rubber compound determines grip, braking distance, wear, and fuel consumption.

H

Tyre Homologation

Tyre homologation is an official testing and approval process. In this process, a tyre is tested by automotive manufacturers and authorities to ensure it meets the required quality and safety standards.

A homologated tyre is therefore specifically approved for certain vehicle makes and models. This approval ensures that the tyre is optimally matched to the chassis, braking system, and performance requirements of the respective vehicle.

Benefits for the customer

• Maximum safety through tested quality
• Optimal driving characteristics, as the tyre is precisely matched to the vehicle
• Legal certainty for registration, as homologated tyres are recognised by authorities

High-Speed Tyres

Tyres specifically developed for sports cars. They offer maximum stability at extreme speeds but often have shorter lifespans.

I

TWI Indicator

The TWI (Tread Wear Indicator) is a small raised bar in the tread pattern. If the tread is worn down to this point, the legal minimum tread depth has been reached. In Switzerland, a minimum of 1.6 mm is required, while 4 mm is recommended for winter tyres.

J

C

Carcass

The carcass is the basic structure of a tyre and consists of fabric or steel cords. It influences the stability and flexibility of the tyre.

Comfort Tyres

Comfort tyres are designed for drivers who value quiet rolling, smooth running, and pleasant driving comfort. They are often tuned softer, but offer less sporty directness.

Contact Patch / Tread Contact Area

The contact patch or tread contact area is the part of the tyre that actually touches the road. For a normal passenger car, this area per tyre is roughly the size of a postcard. Despite this small area, the entire vehicle weight is transferred – including acceleration, braking force, and lateral guidance.

Tread Life

Tread Life

Tread life refers to the number of kilometres a tyre can cover on average before it needs to be replaced. It is an important criterion for economy and value for money.

Factors influencing tread life

• Tyre quality: Premium tyres often have a longer tread life than budget tyres
• Driving style: Sporty driving (heavy braking, rapid acceleration) reduces lifespan
• Tyre pressure: Pressure that is too low or too high leads to uneven wear
• Chassis geometry: Incorrect toe or camber causes increased wear on one side
• Usage conditions: Motorway driving = less wear, city traffic = more stop-and-go and faster wear

Average values

• Summer tyres: approx. 25,000–50,000 km
• Winter tyres: approx. 20,000–40,000 km
• All-season tyres: approx. 30,000–45,000 km
• UHP and sports tyres: often only 15,000–25,000 km

Conclusion: Tread life is not a fixed value, but depends heavily on driving style and maintenance. Regularly checking tyre pressure and rotating tyres can significantly extend their lifespan.

Sipes

Sipes are small, fine cuts in the tread blocks of a tyre. They create additional biting edges and make the tread surface more flexible. This allows the tyres to grip the road surface better – especially on snow, ice, or wet roads.

Sipes are a key feature of winter tyres. They ensure:

• better traction on snow and ice
• shorter braking distances on slippery surfaces
• increased driving stability in difficult weather conditions

Depending on the tyre type, different sipe designs are distinguished, such as straight, wavy, or 3D sipes, each optimised for different driving conditions.

Conclusion: Without sipes, winter tyres would not have their typical safety characteristics. They are crucial for controlled and safe driving even on ice and snow.

Tyre Pressure

The correct tyre pressure is crucial for safety, comfort, and the lifespan of a tyre.

• Tyre pressure that is too low leads to increased wear, longer braking distances, higher fuel consumption, and in extreme cases, can even cause a tyre blowout.
• Tyre pressure that is too high reduces the contact patch, decreases grip, and makes handling more unsafe.

The recommended tyre pressure can be found in the vehicle's owner's manual or on a sticker on the driver's door or fuel filler flap. It is important to check the tyre pressure regularly – at least once a month.

M

MS Marking

The abbreviation stands for Mud and Snow. It indicates that a tyre is suitable for mud and snow. In practice, however, it is only considered a genuine winter tyre feature in combination with the snowflake symbol.

Minimum Tread Depth

The minimum tread depth indicates how worn the tread of a tyre can be before it needs to be replaced. In Switzerland and the EU, the legally prescribed minimum tread depth is 1.6 millimetres (Winter 4mm).

For safety reasons, however, it is recommended to change tyres earlier:

• Summer tyres: minimum 3 mm
• Winter tyres: minimum 4 mm (due to snow and ice)

Tyres with insufficient tread depth lose grip, increase braking distance, and significantly increase the risk of aquaplaning.

The tread depth can be checked with a special tread depth gauge or a simple one-franc or one-euro coin. The small TWI indicators (Tread Wear Indicator) in the tread also show when the legal minimum limit has been reached.

Conclusion: Changing tyres in good time ensures safer driving and avoids problems and liability for costs in the event of an accident.

MOT Switzerland

The Motor Vehicle Control checks vehicles for safety and roadworthiness. Tyres and wheels must be approved either as standard equipment or with a Beiblatt.

N

Wet Grip

Wet grip describes the braking performance and grip of a tyre in the rain. It is one of the most important safety factors and a component of the EU tyre label.

Negative Camber

Camber describes the angle of the wheels relative to the vertical. Negative camber occurs when the wheels are tilted inwards at the top and outwards at the bottom.

Characteristics

• Often used in motorsport and for sporty vehicles
• Provides better grip in corners, as the tyre sidewall sits optimally in the corner
• Significantly alters handling characteristics

Advantages

• More lateral force and stability in fast corners
• Sportier handling
• Better power transfer when cornering

Disadvantages

• Uneven tyre wear (greater wear on the inner edge)
• Shorter tyre lifespan
• Unstable handling on straight roads if set up incorrectly

Conclusion: Negative camber improves performance, but is only sensible if it matches the driving style and intended use. For everyday vehicles, it should remain within the manufacturer's specifications, otherwise problems with the MOT may arise.

Run-flat Tyre

Run-flat tyres have reinforced sidewalls. In the event of a loss of pressure, you can still drive for approximately 80 km at reduced speed. They increase safety, but often offer a harsher ride comfort.

O

Off-Road Tyres

Off-road tyres are designed for off-road vehicles and SUVs. They have a coarse tread pattern that offers more traction on gravel, sand, or snow.

Original Equipment (OE) Tyres

Original equipment or OE tyres, in short, are the tyres that a vehicle manufacturer fits as standard on a new car. These tyres are specifically matched to the respective model and have been developed in collaboration with tyre manufacturers.

Characteristics

• Perfectly adapted to the vehicle's chassis, braking system, and engine performance
• Often feature a special marking on the tyre sidewall (e.g., "MO" for Mercedes, "AO" for Audi, "*" for BMW, "N" for Porsche)
• Undergo an extensive homologation process before being approved

P

Tread Depth

Tread depth indicates how deep the grooves in the tyre are. It is crucial for water displacement, grip, and braking distance.

Legal Requirements

• Switzerland & EU: minimum 1.6 mm (Winter 4mm)
• Below this limit, the tyre is no longer permitted → no MOT inspection, no insurance in case of damage

Recommended Minimum Values for Safety

• Summer tyres: minimum 3 mm
• Winter tyres: minimum 4 mm (better traction on snow and ice)

Dangers of Insufficient Tread Depth

• Increased risk of aquaplaning
• Extended braking distance on wet roads
• Poorer grip when cornering
• Problems with MOT inspection

Measuring Tread Depth

• With a tread depth gauge (accurate)
• With a coin as a quick method:
• 1-Swiss Franc coin: Silver edge = 3 mm
• 1-Euro coin: Gold edge = 3 mm
• Inspection points on the tyre: TWI (Tread Wear Indicator) = small bars in the tread that indicate when 1.6 mm is reached

Conclusion: Changing tyres in good time means more safety, better grip, and less risk on the road.

Tyres

"Pneus" is the term commonly used in Switzerland for tyres.

Q

Aspect Ratio

The aspect ratio denotes the ratio between the tyre height (sidewall height) and the tyre width. It is given as a percentage and is part of the tyre's dimensions.

Example

• Tyre dimensions: 225/45 R17
• 225 = Tyre width in mm
• 45 = Aspect ratio → 45% of the tyre width
• R = Radial construction
• 17 = Wheel diameter in inches
• In this example, the sidewall height is 45% of 225 mm = 101 mm

R

Radial Tyres

Radial tyres are the most common type of tyre construction today. In these tyres, the carcass threads (load-bearing threads in the tyre structure) run radially, meaning at a right angle to the direction of travel – from one tyre bead to the other. A belt made of steel or textile cord is also placed over the carcass, stabilising the tread.

Characteristics

• Marking "R" in the dimension (e.g. 225 45 R17)
• Flexible sidewalls for increased comfort
• Very stable tread due to steel belt
• Lower rolling resistance compared to older constructions

Tyre Test

A tyre test is a comprehensive examination where tyres are tested and evaluated under realistic conditions. The aim is to transparently present a tyre's strengths and weaknesses and to help customers with their purchasing decisions.

Typical Test Criteria

• Braking distance on dry and wet roads
• Aquaplaning behaviour (how quickly the tyre loses contact with the road)
• Driving stability and handling at various speeds
• Wear and mileage (how many kilometres the tyre lasts)
• Rolling resistance / Fuel consumption (efficiency)
• Noise emissions inside and outside
• Price-performance ratio

Well-known Testers

• ADAC (Germany)
• TCS (Touring Club Switzerland)
• ÖAMTC (Austria)
• Automotive magazines such as AutoBild, Auto Motor und Sport

Tyre Rotation

Tyre rotation means swapping the tyres on the vehicle between the front and rear axles (and sometimes diagonally) at regular intervals. The aim is to distribute tyre wear more evenly and extend the lifespan of the tyres.

Why is Tyre Rotation Important?

• Front tyres usually wear out faster due to steering and braking
• Rear tyres often experience more even load but less tread wear
• Regular swapping ensures even tread wear
• Increased safety, as all tyres offer similar grip and braking performance

Recommended Intervals

• Every 8,000 to 10,000 kilometres or at least once per season
• Particularly important for all-wheel drive vehicles, as unevenly worn tyres can cause damage to the drivetrain

Conclusion: Regularly performing tyre rotation saves money, increases safety, and extends the lifespan of your tyres.

Tyre Wear

Tyre wear describes the wear of the tyre tread over the course of use. Every kilometre driven, every braking manoeuvre, and every corner taken contributes to the tread depth decreasing over time.

Causes of Tyre Wear

• Driving style: Strong acceleration, abrupt braking, and fast cornering increase wear
• Tyre pressure: Too low or too high tyre pressure leads to uneven wear
• Wheel alignment: Incorrect toe or camber causes uneven wear (more wear on the inside or outside)
• Tyre rotation: Failure to swap between front and rear axles can lead to different tread wear
• Load: Frequent overloading puts additional strain on the tyres

Consequences of Excessive Wear

• Increased braking distance
• Higher risk of aquaplaning
• Poorer traction on wet or slippery roads
• Problems with the MOT and loss of vehicle registration

Conclusion: Regular checks of tread depth and tyre condition are crucial. Driving safely and saving money in the long run depends on timely replacement and correct tyre pressure.

RunFlat Technology

RunFlat technology refers to tyres that can continue to be driven even after a complete loss of air pressure. This is made possible by reinforced sidewalls and special design features that support the vehicle's weight even without air pressure.

Characteristics

• Continued driving after a tyre failure for up to approx. 80 km at reduced speed (usually max. 80 km/h)
• No need to stop immediately in dangerous locations
• Often marked with "RFT" or "RunFlat" on the tyre sidewall

Advantages

• High safety, as control of the vehicle is maintained even in case of sudden pressure loss
• No spare wheel required → space and weight savings
• Practical for long journeys or regions with poor infrastructure

Disadvantages

• Harsher ride, as the sidewalls are stiffer
• Generally more expensive than standard tyres
• Must always be used in conjunction with a Tyre Pressure Monitoring System (TPMS), as the driver would otherwise not notice a loss of pressure

Rolling Resistance

Low rolling resistance reduces fuel consumption and CO₂ emissions. Eco-tyres are optimised for this, often at the expense of grip.

Tyre Pressure

Tyre pressure is the air pressure inside the tyre, measured in bar. Modern vehicles are equipped with a Tyre Pressure Monitoring System (TPMS), which immediately reports deviations. The correct tyre pressure ensures:

• optimal driving behaviour
• shorter braking distance
• lower fuel consumption
• even tyre wear

The recommended tyre pressure can be found in the vehicle's owner's manual or on a sticker on the driver's door or fuel filler flap. It is important to check the tyre pressure regularly – at least once a month.

Tyre Pressure Monitoring System (TPMS)

The Tyre Pressure Monitoring System continuously monitors air pressure. In Switzerland and the EU, it has been mandatory for new cars since 2014. There are direct systems with sensors in the tyre and indirect systems that use ABS signals.

Directional Tyres

Directional tyres – also known as uni-directional tyres – have a special V-shaped or arrow-shaped tread pattern. This is designed so that they must be mounted in a specific running direction, which is marked with an arrow ("Rotation") on the tyre sidewall.

S

Summer Tyres

Summer tyres are tyres specifically designed for warm temperatures. They are made from a rubber compound that remains stable even in heat, and feature a tread pattern that provides maximum grip on both dry and wet roads.

Characteristics

• Optimal driving performance at temperatures above +7 °C
• Harder rubber compound than winter or all-season tyres
• Fewer sipes, but wider tread grooves for water drainage
• Shorter braking distances on dry and wet surfaces

Advantages

• Higher driving stability at summer temperatures
• Precise steering response and shorter braking distances
• Lower rolling resistance → less fuel consumption
• Longer lifespan than winter tyres in warm climates

Disadvantages

• At temperatures below +7 °C, summer tyres lose elasticity and grip
• Not suitable for snow, ice, or extreme cold
• Although permitted in Switzerland, they are not safe in winter road conditions

Conclusion: Summer tyres are the best choice for use during the warm season. Those who drive in winter should switch to winter tyres by autumn at the latest to avoid compromising safety.

Studded Tyres

Studs are small metal pins embedded in the tread of winter tyres. They protrude slightly from the tread and provide additional grip on ice and packed snow.

Characteristics

• Mainly common in regions with extreme winter conditions
• Offer significantly more traction on icy roads than regular winter tyres
• Recognisable by the silver metal pins protruding from the tyre surface

Advantages

• Maximum safety on ice and packed snow
• Shorter braking distances and better traction in extreme conditions
• Particularly suitable for mountainous regions or Nordic countries

Disadvantages

• Longer braking distances and increased wear on dry or wet roads
• More road noise and reduced driving comfort
• Damage the road surface

Legal situation in Switzerland

• Studded tyres are permitted, but with restrictions
• Maximum speed: 80 km/h on motorways, 50 km/h in built-up areas (observe signage)
• Only permitted from November 1st to April 30th
• Must be marked with a "Spikes" sticker on the rear of the vehicle

Track/Alignment

Track refers to the position of a vehicle's wheels in relation to the direction of travel, as viewed from above. It indicates whether the front wheels are angled inwards or outwards. A distinction is made between toe-in and toe-out.

Types of Track

• Toe-in: The front wheels point slightly towards each other. This improves straight-line stability.
• Toe-out: The front wheels point slightly away from each other. This can provide more agile turn-in with certain chassis designs.

Why is Track Important?

• Correctly adjusted track ensures straight, stable driving
• Prevents uneven tyre wear
• Improves steering precision and safety

Signs of Incorrect Track Adjustment

• The vehicle pulls to one side while driving
• The steering wheel is crooked even when driving straight
• Uneven or rapid tyre wear

Conclusion: Correctly adjusted track is crucial for driving safety and tyre longevity. If any issues are noticed, a wheel alignment should be performed.

Symmetric Tyres

Symmetric tyres have a tread pattern that is consistently the same across the entire tread surface. This means the right and left sides of the tread are identical. This type of tyre is technically simple, inexpensive to manufacture, and widely used, especially on smaller vehicles.

Characteristics

• Tread blocks are arranged mirror-symmetrically
• Can be fitted in any orientation as there is no inside or outside
• Often used on small cars, compact cars, or trailers

T

Load Index

The load index indicates the maximum weight a tyre can carry at a specific air pressure. It is shown as a number on the tyre sidewall, directly after the tyre dimension, e.g., 225/45 R17 91V. In this example, the number 91 means that the tyre can carry up to 615 kg per unit.

Characteristics

• Each value corresponds to a specific maximum load capacity (e.g., 91 = 615 kg, 95 = 690 kg)
• Crucial for vehicle safety, stability, and homologation
• Must always meet the vehicle manufacturer's requirements

Benefits of Correct Load Capacity

• Prevents tyre overloading
• Safe driving behaviour even when fully loaded or towing
• Longer lifespan and reduced risk of tyre damage

Disadvantages of Incorrect Load Index

• An index that is too low leads to overloading, increased heat, and the risk of a tyre blowout
• An index that is too high is permissible but can lead to a harsher ride

Conclusion: The load index is a mandatory value when choosing tyres. Only correctly selected tyres ensure driving safety and will pass inspection by the vehicle testing authority.

Common Load Indexes (Excerpt)

Traction

Traction refers to the transfer of force between the tyre and the road. It describes how well a tyre transmits engine power to the surface. Without sufficient traction, vehicles cannot accelerate, brake, or corner effectively.

Influencing Factors

• Tread Pattern: Deep grooves and sipes provide better grip on snow, ice, or wet surfaces
• Rubber Compound: Softer compounds offer more grip, harder compounds last longer
• Tyre Pressure: Incorrect air pressure reduces the contact area and worsens traction
• Road Condition: Wet, icy, or dirty roads reduce traction

Benefits of Good Traction

• Safe starting even in wet conditions or on inclines
• Shorter braking distances
• More stability in corners

Disadvantages of Poor Traction

• Wheel spin when accelerating
• Longer braking distances
• Increased risk of aquaplaning or skidding

Conclusion: Traction is one of the most important factors for driving safety. Modern tyre tread patterns and technologies are specifically designed to ensure the best possible traction under various conditions.

TWI Tread Wear Indicator

English term for the tread wear indicator, often used synonymously with "indicator".

U

Ultra High Performance Tyres

UHP tyres are designed for sports cars. They offer maximum grip, shorter braking distances, and precise steering, but are less durable.

V

Valve

The valve regulates and maintains air pressure. It is a small but very important component. The valve should be replaced with every tyre change.

Vulcanisation

Vulcanisation is the process by which rubber becomes elastic and stable through sulphur treatment. Every modern tyre is manufactured this way.

W

Winter Tyres

Winter tyres have a special rubber compound that remains elastic even in cold temperatures. Their siped tread pattern provides better grip on snow and ice. While not legally mandated in Switzerland, they are practically essential for safe winter driving.

Wheel Balancing Weights

Wheel balancing weights are attached to wheels to compensate for imbalances. They prevent steering wheel vibrations and uneven tyre wear.

X

Y

Z

Inch

Inch is the unit of measurement for wheel diameter. Example: 18 inches corresponds to approximately 46 centimetres.