Frequently Asked Questions

  1. Air pressure
  2. Aspherical mirrors
  3. Automatic climate control
  4. Bi-turbo
  5. Brake assist systems
  6. Brake booster
  7. Brake compensator
  8. Brake pads
  9. Braking distance
  10. C-type tyres
  11. Controlled deformation zone
  12. Crash sensor
  13. DA tyres
  14. DDE
  15. General operating instructions
  16. Handbrake
  17. Nox emissions behavior
  18. Traction control system (TCS)
  19. Low pressure tyres
  20. Tyre sipes
  21. ABE
  22. ABV
  23. Active Safety
  24. Aerodynamics
  25. Air conditioning system
  26. Airbag
  27. All season tires
  28. Anti-lock braking system (ABS)
  29. Anti-slip systems
  30. Aquaplaning
  31. ASC+T
  32. Aspect ratio
  33. ASR
  34. Asymmetric tyres
  35. Bar
  36. Boxer engine
  37. Brake fluid
  38. Brake force distribution
  39. Carbon monoxide
  40. Cardan shaft
  41. Catalytic converter
  42. Centrifugal force
  43. Circumference
  44. Clutch disc
  45. Commercial tyres (C-tyres)
  46. Compressor
  47. Corrosion protection
  48. Crash test
  49. Cruise System Control (CSC)
  50. Dashboard
  51. Diesel soot particles
  52. Directional tyres
  53. DOT code
  54. Driver information system
  55. ECE symbol
  56. Electric brakes
  57. Electric mirrors
  58. EMT
  59. Engine
  60. Engine power
  61. Exhaust Gas Recirculation
  62. Front/rear tyre marking
  63. Fuel
  64. Fuel consumption
  65. Grip
  66. Heated windscreen
  67. Heated windscreen spray nozzles
  68. Hydraulic brake
  69. Hydrocarbons
  70. Inlet valve
  71. Intercooler
  72. Leaf spring
  73. Low-profile tyres
  74. M+S marking
  75. M/C marking
  76. MFSL
  77. Minimum tread depth
  78. Mixing tyres
  79. ML
  80. Net vehicle weight
  81. Off-road tyres
  82. Oil filter
  83. Oils
  84. On-board computer
  85. Power transmission procedure
  86. Power windows
  87. Profile requirements
  88. Regroove
  89. Rims
  90. Rocker arm
  91. Rolling resistance
  92. Roof load limit
  93. Roof racks
  94. Rubber compounds
  95. Run-flat tyres
  96. Satellite navigation system
  97. Shut-off valves
  98. Sidewall
  99. Soundproofing
  100. Speed
  101. Speed rating
  102. Stop
  103. Stop lamps (brake lights)
  104. Storing the tyres
  105. Suspension
  106. The clutch
  107. The life of a tyre
  108. The pressure plate
  109. The sidecar
  110. Tow bar for PKW
  111. Tread
  112. Tyre coating
  113. Tyre cord fabric
  114. Vehicle axles
  115. Wheel balancing
  116. Wide tyres
  1. Air pressure

    Making sure that you use the proper air pressure is extremely important as it has an important impact on the tyres' durability and on driving safety. If the air pressure is too low, the rolling resistance is increased and this can lead to a higher fuel consumption. Official reports show that only one in four cars are using the correct air pressure. The tyre pressure recommended by the car manufacturer can be found in the handbook of that vehicle, on the fuel filler flap or on one of the door posts, usually the driver's. The air pressure should be checked at least every four weeks. The air pressure test should be performed on "cold" tyres (before the vehicle is driven and heat is generated).
  2. Aspherical mirrors

    The aspherical mirror features a split mirror surface that has a convex curvature that increases the driver's rear view angle. This allows the driver to see more of the back of the car and following traffic. So the driver can avoid the blind spot that occurs when looking in a conventional flat mirror.
  3. Automatic climate control

    The automatic climate control offers the driver an extra comfort while driving. Using the automatic programming function, a comfortable temperature can easily be reached and maintained. The temperature can also be set manually.
  4. Bi-turbo

    Bi-turbo refers to an engine that has two turbochargers (bi = two). These turbochargers are mounted on either side of the engine. It is also known as "twin-turbo".
  5. Brake assist systems

    A sensor records every operation of the brake pedal thus observing the force with which the brake pedal is pushed. This sensor alerts the driver through an audio or visual signal if he exceeds the posted speed limit: “Warning: emergency brake!” A solenoid valve that ventilates the booster and increases the brake pressure is activated. As soon as the driver releases the brake pedal, the brake assistance is automatically disabled.
  6. Brake booster

    Brake boosters or brake servos are auxiliary braking devices designed to help improve braking performance. The power that the driver uses when braking is assisted by these brake boosters. This booster is significantly important for brake pads as they require a higher hydraulic pressure. The boosters are controlled mechanically by using the brake pedal hydraulics. In case of pressure loss, this system works as a hydraulic brake system although an increased foot braking pressure has to be appliedby the driver. The human power alone is usually not enough in order to reach the required braking force that cars, commercial vehicles or buses need. Servo-pneumatic power is used as the additional force. Brake fluid systems can be pneumatic or hydraulic. When it comes to cars, a servo pump can be added by using the servo system. Nowadays, almost all cars are equipped with adequate boosters.
  7. Brake compensator

    Also known as proportioning valve or disc brake valve, it refers to the distribution of brake force that ensures the equal increase of pressure in both front and rear axles. When reaching the switching point, this brake regulator ensures that only a low pressure is enforced upon the rear axle. This happens when pressure increases.
  8. Brake pads

    The brake pads are responsible for partially locking or stopping the wheels when the brake pedal is pressed. This occurs on vehicles that do not have anti-lock braking systems (ABS). If the pressure that occurs is too high, the tyres can be damaged by causing flat spots.
  9. Braking distance

    This refers to the distance a vehicle will travel from the moment the brakes are ressed until the wheels completely stop. The braking distance is influenced by many factors including the driver's reaction time, the road conditions, the vehicle’s speed and the tyres that are being used (manufacturing pattern type, tread depth, air pressure and evenness of the wear).
  10. C-type tyres

    Having a high load carrying capacity, C-type tyres are specially made for commercial vehicles, vans and light trucks. These tyres can be used on small trucks, transport trucks, platform trucks, trailers, vans or any other vehicles that have to carry heavy loads at any speed. Multilayered carbonor steel wire reinforced tyres are the best solution for heavier vehicles (HGVs).
  11. Controlled deformation zone

    The purpose of the controlled deformation zone is to uniformly divide the energy generated by an impact. The car's bodywork must be stable and should have a fixed structure (thus providing passive safety).
    The front and the rear sides of the car must have the so-called "crumple zones". When the front and the rear sides of the car are deformed, a part of the kinetic energy is stored by the bodywork. Thus, the passengers are protected during an impact. During the so-called "crash-test", these crumple zones are also tested.
  12. Crash sensor

    In the event of an accident or major impact, the crash sensor is activated along with the hazard lights. The crash sensor unlocks all doors allowing the emergency crews to get into the car.
  13. DA tyres

    This refers to tyres that are considered “devalued” or have a Defective Appearance by the tyre manufacturer because of some visual flaw(s). These tyres are considered technically soundin construction and opperation and totally suitable for driving. They carry the mark “DA” stamped on the sidewall. There should not be any issues during their usage.
  14. DDE

    This abbreviation stands for “Digital Diesel Electronics” system. DDE controls the process of fuel injection, the fuel efficiency and the boost pressure. Extremely precise, DDE makes sure that the diesel engine is running properly. A greater fuel efficiency and lower emissions are among DDE’s positive beneficial effects.
  15. General operating instructions

    A general operating instruction (ABE) is required to register a vehicle and for it to be allowed onto public roads. The official document for ABE is the KFZ label, the registration certificate. In this document among other things are - country details, the number of seats, codes and trailer information, also changes in TUV licensed cars (width of tyres, bodywork components etc.). Changes that were made to the vehicle and were not reported in the label may invalidate the KFZ EBA's and are punishable by law.
  16. Handbrake

    The legislation requires that all cars must have two independent brake systems: the service brake (or the foot brake) that acts on each wheel and the emergency brake assist (or the handbrake) that acts either on the rear wheels or on the front wheels. The handbrake is triggered by pulling a lever or by using an extra pedal. The handbrake device is made of a cable system that triggers the mechanism by pulling the lever in the proper position. If the service brake fails, the handbrake can be used as an alternative. When driving at high speed, the driver must be careful when using the handbrake as it may cause the vehicle to swerve.
  17. Nox emissions behavior

    The behavior of Nox emission describes the feature of an engine to determine the quality of “gases” while functioning.
  18. Traction control system (TCS)

    When you accelerate harshly or especially when you are on a smooth road, the TCS prevents the wheel from slipping. The wheels will automatically be decelerated and the engine's power will be reduced. The TCS improves the traction when the car is being steered too. A slalom test showed that a car without TCS slips while the one with TCS remains still on the road.
  19. Low pressure tyres

    Also known as "balloon tyres", low pressure tyres have a large volume of air and high elasticity; its weak features become obvious when driving on twisty roads.
  20. Tyre sipes

    Tyre sipes are thin slits on a moulded into a tyre's tread. On winter tyres, they improve traction when speeding up and increase safety when braking.
  21. ABE

    Abbreviation for “General operating instructions”.
  22. ABV

    ABV - automatic brake blocking. The anti-lock prevents the wheels from locking during braking by controlling the brake pressure so that the vehicle remains steerable. Depending on the vehicle, the type of ABV and the road surface, a reduction in the braking distance can be expected. See also ABS and ESP.
  23. Active Safety

    Active safety technical measures on the vehicle refer to the (positive) influence the "active" driving behavior and how to avoid accidents. Amongst other features, active safety is assured by the chassis . It is supported by the excellent braking system with ABS as standard. Also, the power steering with its precisely defined steering force feedback helps to better handle critical situations.
  24. Aerodynamics

    Aerodynamics refers to the power shifts that affects suspended bodies. The concept has been used in the automotive industry for some time because air resistance was noticed as an important factor in a car's operating costs. At the beginning of the automotive industry, cars were built practically. Nowadays, they are built aerodynamically. The more aerodynamic the car's body is, the less power is required in order to reach a certain speed and the smaller the engine required. The wind tunnel and the water tunnel are based on the experiences that have come from aircraft construction and is applied still today in the automotive industry. Usually, the result is pretty level because the air drag only allows for the existence of certain forms.
  25. Air conditioning system

    The air conditioning system is made of a cooling system, a heating system, a humidity control system and a ventilation unit. The air conditioning system assists the vehicle’s heating and ventilation systems.
    Unlike the automatic climate control (the Climatronic system), the air conditioning system is manually controlled by the driver. Besides adjusting the temperature, the air conditioning system also controls the air’s circulation and humidity; it also offers control on how clean the air is inside a car. Air cooling is based on the same functioning principle as a heat pump. The heated air is put through a fan and sent into an evaporator where the heat is removed. The defrost function can be activated during the cold season.
  26. Airbag

    Driver, passenger and lateral airbags protect against head and chest injuries that can occur in a car accident. The driver's airbag is integrated into the steering wheel. The passenger's airbag is integrated into the dashboard's plastic panel whose stitches break when triggered. During an accident, a sensor (located at the front of the dashboard) triggers a pyrotechnic gas generator that fills up the airbag with nitrogen in less than 50 milliseconds. The full size version of the driver's airbag can hold 80 liters of gas and the passenger's airbag can hold up to 150 liters of gas.
  27. All season tires

    When it comes to car tyres, besides using summer or winter tyres, producers offer a third option:all season tyres. These tyres can be used all year round, regardless of the season.
    All season tyres carry the “M+S” marking just like winter tyres and are also known as “all-weather” tyres. Their symbol is molded into the tyre’s sidewall and symbolizes various weather conditions; it can either be a snowflake, a leaf or a sun and rain drops symbol. These type of tyres should only be regarded as a compromise as their performance in extreme weather conditions (high temperature or extreme cold) is not ideal.
  28. Anti-lock braking system (ABS)

    ABS anti-lock braking system prevents wheel locking up and stopping suddenly. Advantage: the car remains fully steerable! A central electronic control device with speed sensors at each wheel reduces the number of revolutions of a wheel - or all wheels, recognizes the danger of locking and immediately reduces the brake hydraulic pressure to that wheel. The type of ABS hydraulic unit contains 3 to 4 channels at the wheel brake cylinders. On wet or dry roads, the braking distance is usually the same or less as the same vehicle without? ABS. Braking distance may be longer on snow or gravel. Attention: for emergencies push the brake pedal "hard".
  29. Anti-slip systems

    The functioning of the electronically based anti-slip systems (ASS) is to prevent the spinning of the drive wheels. Using sensors, the driving force is distributed so that no wheel gets more power than it actually needs to drive it. In contrast to the limited slip differential that operates mechanically, the spinning of the wheels does not ultimately prevent it with anti-slip systems. Engine performance is also influenced, so that the wheels get fed only as much power as is actually necessary. Some systems may affect the brakes at speeds of up to 40 km/h and thus prevent the wheels from spinning.
  30. Aquaplaning

    It occurs when the water that accumulates between the wheels on the vehicle and the road surface cannot be directed to the tyre's surface and is too much for their tread gooves. The tyre will "hover" on that water which can lead to malfunctioning steering and to the loss of kinetic energy. Aquaplaning is distinguished by light steering, simultaneous wheel rotation and the sound of water underneath the vehicle. During aquaplaning, the driver must not brake suddenly; he should slowly release the accelarator pedal and continue controlling the steering wheel in the direction of the road. When the car is back on the track, make sure the wheels do not lock or be positioned in the wrong direction of travel. When the car is set on cruise control, the driver must be very careful on twisty roads. Indeed on wet roads it is better not to engage cruise control at all. Drive safely in the rain!
  31. ASC+T

    Automatic Stability Control plus Traction (ASC+T) prevents wheel spin and provides driving stability. Up to a speed of 25 mph, the ASC+T system adjusts the brakes, automatically blocking the wheels from spinning. At speeds of more than 25 mph, slipping is inevitable.
  32. Aspect ratio

    The aspect ratio refers to the height of the sidewall divided by the tyre's width. Let’s take for example the following tyre size: 175/70 R13 S. In this case, 70 indicates that the tyre’s height is equal to 70% of its width. This is also known as a “70 series tyre”. Nowadays, on the tyre market, series range between 80 and 25. Tyres that have an aspect ratio of 55 or lower are regarded as “low profile tyres”.
  33. ASR

    When you speed up or are driving on slippery roads, it handles the side-slip(ASR) of the driving wheels when spinning. If spinning, the wheel is automatically braked and the engine power slowed down. Also ASR improves the grip in bends.
  34. Asymmetric tyres

    This refers to tyres that do not have either a uni-directional or directional pattern. Therefore, these tyres are cross rotated and can be fitted both on the left or the right side of the vehicle. After fitting asymmetric tyres, they may look as if they have been mounted backwards. It is compulsory to follow the instructions when mounting this type of tyre. They have either an "inside-outside" pattern identicator or a "this side out" marking.
  35. Bar

    Bar is a metric air pressure measurement unit. The Imperial air pressure measurement is pounds per square inch (psi).
  36. Boxer engine

    When it comes to the boxer engine, the pistons are operating in an 180° angle on the crankshaft's sides. This is the reason why this engine design is also known as "the V engine". Because of the design, the engines are flat and require less engine bay height. The most famous boxer engine is the one that was produced for the VW Beetle. The most remarkable evolution of a boxer engine is found in Porsche 911 cars.
  37. Brake fluid

    The brake fluid is made of "Polyalkylenglycol" (highly poisonous and corrosive) and other additives. Their purpose is to transmit pressure from the brake pedal and the brake cylinder to the hydraulic brake system. The brake fluid’s boiling point is 290 C° in order to avoid creating vaporisation when the brakes are firmly pressed. The hygroscopic nature of the brake fluid requires it to be changed at the prescribed service intervals. A small quantity of water can significantly lower the boiling point and can cause air bubbles. This has a negative effect on the braking pressure because the gas (air) can be compressed unlike the brake fluid.
  38. Brake force distribution

    By changing the weight dynamic in relation to the position of the brakes, the front wheels must acquire a higher braking power in order to avoid locking the rear wheels when the brakes are used. When it comes to front-wheel drive vehicles, the front axle of the vehicle is always heavier than the rear axle. This means that the center of gravity is located to the front of the vehicle. In this case, the center of gravity can be balanced by using rear wheel cylinders. This is how the proper distribution of the brake force is achieved. It is important for driving safety to make sure that the brake force is properly distributed. In order to achieve that, the following things are required: an anti-lock braking system that reduces the braking pressure and a valve that blocks that pressure and keeps it on the rear wheels. The valve's blocking becomes useful when a certain hydraulic pressure is reached. The brake pressure regulator equally divides the pressure between the front and rear wheel brakes. When the switching point is reached and the pressure on the front axle increases, the brake pressure regulator helps to balance the overall pressure. Individual brake pressure regulators are similar to the typical brake pressure regulators with the distinction that the first type controls the switching point according to the load status thus preventing the rear axle from locking. This way, the vehicle’s handling is controlled by connecting the axles to the rear of that vehicle.
  39. Carbon monoxide

    The carbon monoxide is an odorless gas produced by an incomplete combustion (exhaust gas). If carbon monoxide is accidentally inhaled, it can get into the bloodstream where it affects the oxygen-carrying capacity of the blood.
    In higher concentrations, the carbon monoxide can cause headaches and dizziness; in extreme cases, it can lead to fainting or death by asphyxiation.
  40. Cardan shaft

    Also known as the drive shaft, this mechanical device is used on rear wheel drive vehicles that have the engine and the gearbox fitted in the front of that vehicle. The cardan shaft is used to make a differential connection between the engine, the gearbox and the wheels. In order to do this, a plaque that makes a connection with the rear axle is attached outside the gearbox. This cross-shaped plaque is known as the cardan shaft. This is made of a metal cylinder that can be adjusted in terms of thickness and length so that it meets the vehicle’s requirements and its size (in most cases, the distance between the gear box and the driving axle). The cardan shaft can be made of a single piece of metal or it can be articulated.
  41. Catalytic converter

    The three way catalytic converter is the most effective, safest and most reliable form of cleaning pollutants produced by engines that run on gasoline. Polluting gas emissions like the carbon monoxide, hydrocarbons and nitrogen oxides are transformed into less effective polluting compounds like carbon dioxide, water and nitrogen. Stricter emission regulations were established in 1985 for all vehicles.
    A well adjusted catalyst can improve the amount of emissions up to 90%. The required optimal composition of gas and air mixture for the converting process is adjusted by the lambda sensor and the engine control system. Although improvements have been made over time regarding the effectiveness of catalytic converters, the level of gas emissions still needs to be drastically reduced.
    New technologies regarding catalyst development and the usage of new fuels have a great contribution to reducing toxic emissions.
  42. Centrifugal force

    This refers to the force that makes the car push towards its exterior radius when the wheels are turning. Depending on the vehicle’s mass and speed, this force can be stronger or weaker.
  43. Circumference

    Is the rolling distance from one point on the tyre for a complete revolution. So that the circumference relates to the tyre diameter. It has influence on the transmission ratio and the speedometer. With a lower tyre series (aspect ratio), this smaller circumference tyre has the tendency to a shorter transmission Acceleration is affected favorably, but at high speeds there is the possibility of staying in the tachometer's red zone. In addition this smaller tyre will make the speedometer read higher. Acceptable tolerances are from plus 1.5% to minus 2.5%. The larger deviations will have made ??a proportionately bigger change to the speedometer's reading.
  44. Clutch disc

    The clutch disc is a part of the clutch. It links the engine and the transmission.
  45. Commercial tyres (C-tyres)

    Tyres specifically designed for light trucks, trucks, vans and buses. The priorities of these tyres are high mileage and fuel economy.
  46. Compressor

    This refers to the mechanism that separates the air and compresses the gases; it has the same role as a reciprocating piston. The compressors' main purpose is to compress the air required in the combustion process and also to control the air flow required to increase a cylinder's capacity. This increases the engine's power and its rotation frequency (RPM or the revolutions per minute).
    Turbochargers are controlled by the exhaust gases' energy flow and do not require additional energy. A compressor's advantage is given by its dissipation power that occurs early in the process; this leads to a constantly growing power. Nevertheless, the turbocharger lag only occurs at a certain speed of the engine (discharge rate).
  47. Corrosion protection

    Complete corrosion protection is regarded nowadays as standard for all relevant vehicle related areas. Bodywork areas are protected against corrosion by using hot wax. Riveted and welded parts are also protected against rust. Plastic insertions protect the vehicle against accidental impacts with stones.
    Electrolyte sheets are partially or fully galvanized. A basic corrosion protection is applied through the process of phosphating and through the use of cathodic dip. Moreover, a special corrosion coating system is used along with a PVC layer to protect the cavities and the bodywork's lower part.
  48. Crash test

    This form of testing is used in developing and testing car safety. It uses both elaborated software programs and physical models made of special materials to simulate various types of accidents. The purpose of these tests is to improve passenger safety, reduce the pressure on passengers during a crash and to maintain the injury risk as low as possible for traffic participants (pedestrians, cyclists, etc.)
  49. Cruise System Control (CSC)

    This electronic system is also known as “autopilot”. The driver can set the speed to a particular rate and the autopilot will maintain that speed until further notice - for example braking or swiching the system off.
  50. Dashboard

    The dashboard contains multiple display devices, measuring instruments, control devices, lights, airbags, switches, radio etc. In the past dashboards were not as technologically endowed as they are today.
  51. Diesel soot particles

    Depending on the engine’s type, the soot particles from a diesel engine usually include soot (carbon), unburned fuel, sulphur compounds, oil and metals. It is said that emissions coming from a diesel engine can have a damaging impact on health.
  52. Directional tyres

    For maximum performance, directional tyres must be fitted to rotate in a certain direction. This type of tyre has the following advantages: reduced road noise, better wet grip and greater resistance to aquaplaning.
    Asymmetric tyres and most of high performance tyres are all directional. These tyres have a directional arrow indicator on the sidewall.
  53. DOT code

    DOT is short for “Department of Transportation” and refers to a code made of three or four numbers molded into a tyre’s sidewall. This code indicates the tyre’s manufacturing date and implicit how old that tyre is. For instance, “327” indicates a tyre that was manufactured in the 32nd week of 1997. Starting from 2000, the DOT code has four digits. For example, “1602” refers to a tyre that was manufactured in the 16th week of 2002.
  54. Driver information system

    Because electronic devices are often found in cars produced nowadays, driver information systems are a natural consequence of this evolution. The driver has access to all sorts of relevant information displayed directly on the dashboard: temperatures, important information about the proper working of the engine, average fuel consumption etc.
  55. ECE symbol

    The 36th regulation of the Road Traffic Act states under section 4 (wheel description) that the following details must be present on all tyres that can run at speeds of more than 25 mph or 40 km/h: tyre size, speed index and manufacture date (DOT code). The E-mark label is compulsory for tyres sold within the European Union after July 1997.
  56. Electric brakes

    The electric brakes are part of a mechanism that deals with energy recovery. When braking, the alternator acts like a generator and converts the kinetic energy into electrical energy. Both electric and hybrid vehicles use this mechanism.
  57. Electric mirrors

    The electric adjustment of the mirrors is done from inside the car, either from the driver’s side (both mirrors) or the passenger’s side. The mirrors can be adjusted according to the height and the longitudinal axis that the driver requires. The electric devices that are integrated in these mirrors adjust the viewing angle. Some electric mirrors have a memory function that allows them to go back to the default position. For instance, after the mirrors are washed. Often electric mirrors have demisting elements within the glass too.
  58. EMT

    This abbreviation refers to a tyre with "extended mobility technology" (EMT) - also known as run-flat tyres. When facing total loss of air pressure, the EMT tyres can travel up to 50 miles / 80 km at a speed of no more than 50 mph / 80 km/h. This should give the driver enough time to get to the nearest auto service or tyre dealer.
  59. Engine

    By definition the word engine is used to represent a force that transforms some form of energy into mechanical energy (to power other machines, a car and so on). The engines differ by their combustion type and the types of fuel they use.
    The most common are: petrol, diesel, electric, turbine or gas engines and hybrid engines. Configurations can be in-line, V or boxer and with 2, 3, 4, 5, 6, 8, or 12 cylinders.
  60. Engine power

    The actual power of the engine is not calculated but measured on the test bench. These measurements focus on the power of the engine rather then on its speed.
    The maximum engine power was calculated before in PS and now in kw or bhp (also called “nominal power”). With the help of this value, the insurance rating is calculated.
  61. Exhaust Gas Recirculation

    In the normal combustion cylinder process, nitrogen oxides increases disproportionately with increasing firing temperatures. By recirculation of the exhaust gases only a part of it is introduced to reduce the temperature of burning. The exhaust gas recirculation system is composed of a driving pump and is electronically controlled by a fan. Exhaust gas recirculation is an effective method for reducing nitrogen oxides.
  62. Front/rear tyre marking

    This is a special marking used by tyre producers to ensure that the tyres are fitted on the correct axle of the car. Tyres marked “front'’ should be mounted on the front axle whereas tyres marked “rear” should be fitted on the rear axle.
  63. Fuel

    The fuels used for internal combustion engines are gasoline and diesel. Usually, fuel is obtained from petroleum distillation and in order to be used in vehicles, they must be as pure as possible (without any solid impurities). Fuels based on gasoline have specific densities and different octane rating or numbers:
  64. Regular gasoline (91 RON)
  65. Super (95 RON)
  66. Super Plus (98 RON)
  67. RON stands for "research octane number" and represents the standard rating for fuel performance (vehicles and aircrafts). The higher the octane rating, the more compression the fuel can withstand and can be used on high-compression engines. Diesel fuel is obtained from petroleum distillation between 180°C and 380°C. The quality and the properties of gasoline and diesel are determined by the additives they have in their composition. Among other things, these chemical additives ensure storage stability, high detonation resistance and anti-corrosion properties. When it comes to the additives that are found in diesel fuel, they improve fluidity in temperatures below the freezing point and prevent the occurrence of ice crystals on the car's throttle. When using catalysts, it is mandatory to use unleaded fuel.
  68. Fuel consumption

    Buyers can evaluate the cost of a vehicle by analysing its averagefuel consumption data. This data is influenced by several factors like the vehicle’s speed and weight, engine’s speed and efficiency, etc. Fuel consumption is an important issue not only from an economic point of view but also from an environmental perspective.
    Car manufacturers must carry out three technical tests regarding the fuel consumption in order to determine the urban cycle, the extra-urban cycle and the overall consumption. The average fuel consumption is calculated by combining the results with a ratio of 36.8% for the urban cycle and a ratio of 63.2% for the extra-urban cycle. The testing begins with the urban cycle and the "cold start" (around 20°C - 30°C). The consumption is calculated based on the resulted emissions (including the CO2 emissions).
  69. Grip

    This refers to the phenomenon that occurs between a vehicle’s wheels and the road. This ensures vehicle movement.
  70. Heated windscreen

    Heated windscreens are made with heated wire elements. These wires are embedded in the windscreen's glass layers and do not affect in any way the driver's visibility.They are very thin and can quickly thaw out the accumulated ice or misting. A heated windscreen has the advantage of saving time and removes the stress of manually clearing the moisture or ice layers.
  71. Heated windscreen spray nozzles

    Heated spray nozzles are very useful during the cold weather season because the water they are spraying on the windscreen does not freeze.
  72. Hydraulic brake

    For security reasons, the hydraulic brake system is divided into two braking circuits; usually, two diagonally opposite wheels form a brake circuit (for instance, the front right wheel and the rear left wheel). If one of the circuits fails, the other one will take over. This can cause the car to spin but the sway bar (also known as the stabiliser bar) will help to stabilise the car.
  73. Hydrocarbons

    Hydrocarbons can occur in various forms in the exhaust gases. Their odor can be different (aromatic or pungent). In high concentrations, some hydrocarbons can have a narcotic effect while others can irritate the mucous membranes. Depending on their nature, they are more or less toxic. Benzene, an aromatic hydrocarbon, is classified as carcinogenic. Hydrocarbons have a major importance in smog formation.
  74. Inlet valve

    The inlet valve’s main purpose is to make sure that when the air travels through the engine, the emission paths are opened and closed at the right moment. The whole system is made of an inlet valve and an exhaust valve. These two valve types are always present in standard engines.
  75. Intercooler

    The radiator (part of the car's original equipment) should be changed occasionally as it cannot always cope with the high temperatures resulted from various engine alterations. By using an intercooler, temperature rates can drop down to 40-55 degrees and power will increase by 12-13%; other benefits: better and lower fuel consumption and lower emissions.
  76. Leaf spring

    Flat leaf springs have one or multiple tempered steel layers (strips); sometimes they contain intermediary zinc or rubber layers to reduce the noise level. Their pressure point is located in the middle of the structure thus creating compression load. Flat leaf springs are difficult to use on cars.
  77. Low-profile tyres

    The tyre section describes the ratio between height of a tyre to its width at the tread edge. The balloon tyre in the 1920s had a height-width ratio of about 1:1 compared to the low-profile tyres of today that can have a ratio of as low as 0.25:1.
    Low-profile tyres are those where the ratio of the tyre's height to width is less than 80%.
  78. M+S marking

    M+S (also known as M&S or M.S) is a standardized marking that indicates a tyre which offers good grip and safe driving conditions on mud covered roads and in snow and ice conditions.
    The M+S tyres (mud and snow) that also have the snowflake symbol are regarded as high quality tyres. Besides the M+S marking, winter tyres also carry the alpine symbol (also known as the three peak mountain snowflake symbol).
  79. M/C marking

    The M/C marking indicates a motorcycle tyre. This marking is moulded into the tyre's sidewall.
  80. MFSL

    This abbreviation refers to tyres with rim protection ridges on the sidewall and comes from the German syntagm "mit Felgenschutzleiste". This ridge helps tp protects the wheel rim from hitting or rubbing against other surfaces (e.g. kerbs).
  81. Minimum tread depth

    For the cars, trucks and motorcycles in Europe, the minimum tyre depth is 1.6 mm. This minimum has to be present on the whole tyre. When this depth is reached, the braking distance will increase on wet roads, and the risk of aquaplaning also increases. The braking distance is double compared to a new tyre.
    For safety reasons, summer tyres should be replaced when the minimum tread depth reaches 2 mm, winter and wide tires at 4 mm.
  82. Mixing tyres

    Even though it is not expressly forbidden, experts and tyre manufacturers do not recommend the use of tyres produced by different manufacturers and with different tread profiles (for example if you use two tyres summer and two winter tyres fitted to the same vehicle.
    Safety while driving can be affected as these tyres are designed to meet specific standards for each season). Running on summer tyres in the winter, on a frozen road, will cause the wheels to lock faster and lead to abrupt braking, locking the tyres and resuling in a skid. Also, it is totally forbidden to fit different sized tyres on the sameaxle, except the fitting of an emergency spare wheel and tyre to be able to drive to the nearest fitting station.
  83. ML

    This abbreviation is used for tyres with special uses - heavy machinery used in construction, mining and logging.
  84. Net vehicle weight

    This refers to the net weight of a vehicle without taking into account the driver, the passengers or any other additional weight. When it comes to commercial vehicles, 75 kilograms are automatically added for the driver.
    Payload refers to the difference between the vehicle’s own weight and vehicle’s gross weight. The vehicle gross weight refers to the maximum operating weight that a vehicle should not exceed.
    Roof load limit refers to the weight that can be carried using roof racks and roof boxes. Usually, this limit is between 50 and 100 kilograms.
    Towing capacity refers to a trailer’s mass excluding the vertical load on the coupling point of the vehicle. This usually ranges between 50 and 75 kilograms.
  85. Off-road tyres

    This refers to a type of tyre designed for use on rough terrain, muddy or uneven surfaces - usually they are fitted to SUVs, 4x4s, etc.
  86. Oil filter

    Particles of dirt, sand and combustion residue contaminate the engine oil and reduce its lubrication. The oil filter which is integrated the oil's circuit, filters this residue.
    To protect the longevity of the engine, it is recommended to change the oil filters at the vehicle's prescribed mileage or time intervals.
  87. Oils

    Oils play an important role in a vehicle as lubricants. Lubricants are separating factors between two moving parts.
    The oil prevents direct contact between the components involved, minimizes friction and reduces wear. Oil is present as a lubricant in the engine and transmission. Engine oils most commonly used are made of mineral oil using various additives in the composition. Oils also allow bigger intervals between engine and transmission oil changes. Oil quality depends on viscosity (SAE) and the effectiveness of additives.
  88. On-board computer

    The on-board computer offers electronic information to the driver (average fuel consumption, estimated range, distance to destination, estimated time of arrival etc). All this information is displayed on the on-board computer and can be accessed at anytime while driving.
  89. Power transmission procedure

    It refers to the wheels' rotation while the axles are in motion. Wheel rotation is different on roads with curves as the wheels on one axle do not react in the same way on these kind of roads. The exterior wheel rotates faster than the interior one. The process responsible for this situation is called "wheel compensation". This process transfers the power to the wheel that has better traction.
  90. Power windows

    Also known as electric windows, power windows are a feature present in most vehicles nowadays. In order to raise or lower the windows, an electric device is mounted in the car’s doors. This device allows the driver to open the passenger window and often the rear windows too. Depending on the car model, the buttons that activate the electric windows are placed on the car’s doors or in the center console. In most cases, the windows can be locked using the parental control option located on the dashboard.
  91. Profile requirements

    Each tyre has to ensure the sustainability of the vehicle weight and possibly to transmit high driving forces, braking forces and side forces - on dry roads, wet roads or where humidity, moisture, snow or ice are present. Other requirements include: high-speed stability, robustness, abrasion resistance, low rolling resistance, low noise, suspension properties, good handling, aging resistance.
  92. Regroove

    Regrooving is usually practiced on specific types of tyres for commercial vehicles. It is recommended that the regroove is carried out by a tyre professional. It is recommended to do this when there is a minimum 3 mm left on the original tread pattern – a regroove that is too deep can prematurely destroy the tyre.
    Regrooving is not recommended if the rolling tread shows signs of deterioration - for eaxmple uneven wear or chunking of the tread area.
  93. Rims

    Rims can be made of steel, aluminum or a mixture of various metals. Most car wheels produced today are made of alloys. These rims made of aluminum or other metals are more attractive, provide better rotation and reduce the overall weight of the vehicle. A tyre fitted on a rim forms a complete wheel set.
  94. Rocker arm

    The rocker arm is a component of the stabilizer bar and helps connecting the wheel to the car body. It has a triangular shape; two of the triangle’s sides are attached to the car body while the third side is attached to the wheel.
  95. Rolling resistance

    Rolling resistance is the force resisting the tyre rotation. Due to the new manufacturing technologies, the rolling resistance was been significantly improved. This is definitely an advantage as the consumption of fuel is reduced.
  96. Roof load limit

    This refers to the weight that can be safely carried on a car using a roof rack. Depending on the car, the weight limit is between 50 and 100 kilograms. If these values are exceeded, the roof rack may break or detach its self with consequent accident potential.
  97. Roof racks

    Mounted on the roof of the car, roof racks are used to carry large items (e.g. bicycles), increasing the vehicle’s storage capacity. They may reduce the vehicle’s stability and so it's safety and increase fuel consumption. With every kilogram added to the roof, the center of gravity moves toward the top of that vehicle. On bendy roads, this can lead to accidents if the driver is not careful when braking. It is best to avoid using a roof rack and choose another storage option for example a rear mounted biicycle rack. If this is not possible, make sure you adjust your driving style to the transported weight. Prior to driving off, the roof rack's security should be checked for tightness and centering.
  98. Rubber compounds

    A tyre can have up to 16 different rubber compounds in its structure. The exact composition of a tyre cannot be known as it varies from manufacturer to manufacturer. Usually, in order to produce a high quality tyre, the following requirements are compulsory: low abrasion, high tensile strength, dynamic and skid resistance, tightness and high wear resistance.
  99. Run-flat tyres

    Run-flat tyres or totalmobility tyres are designed so that despite any loss of pressure, the tyre will not come off the rim. So this offers the possibility to drive on the deflated tyre safely for up to 50 miles (80km) at no more than 50 mph (80 km/h).
    This will provide you with sufficient distance to get to a tyre fitter or a dealer.
  100. Satellite navigation system

    The navigation system guides you quickly and directly to any destination. The satellite system determines your location by GPS (global satellite positioning) and its computer can calculate the shortest, fastest or most economical route to your destination.
    The computer provides the necessary voiced instruction information and also on the screen you will have further directional information.
  101. Shut-off valves

    In case of an accident, these shut-off valves will stop the fuel flow and reduce the risk of explosion or fire.
  102. Sidewall

    The tyre’s upright edge is commonly known as the sidewall. It has a great influence on how the car drives and handles.
  103. Soundproofing

    A low level of vehicle noise is a mandatory requirement for a comfortable ride. This also has a positive impact on the environment. The noise caused by the wind can be reduced by better aerodynamics whereas the noise caused by the engine or external traffic can be reduced by using vibration dampers.
  104. Speed

    As every engine produces a certain maximum power at a given speed (KW), driving without a gearbox would be difficult and uncomfortable. It would be like driving using only the first gear. This maximum power occurs between the idle speed (about 600 U per minute) and the maximum speed (about 6.500 U per minute). The engine can only be properly operated at full capacity by using the gearbox.
  105. Speed rating

    The speed rating refers to a one-letter symbol molded into the tyre’s sidewall. For instance, when reading the following tyre size 195/65 R15 H we see the letter “H”. This letter indicates that particular tyre is safe to 130 mph (or 210 km/h). The most often found speed ratings are:
    Q = 99 mph (160 km/h), R = 106 mph (170 km/h), S = 112 mph (180 km/h), T = 118 mph (190 km/h), H = 130 mph (210 km/h), V = 149 mph (240 km/h), W = 168 mph (270 km/h), Y = 186 mph (300 km/h), ZR = over 150 mph (240 km/h).
    In order to see what speed rating is approved for your car, please check your vehicle’s handbook.
  106. Stop

    The reaction pathway and the actual braking distance, on which the speed is finally slowed, constitutes the stopping distance.
  107. Stop lamps (brake lights)

    Due to the pressure generated in the braking system, a switch is triggered activating the brake lights symmetrically that are fitted at the left and right edges of the rear of every road vehicle.
  108. Storing the tyres

    Drivers are usually forced to store the winter tyres during the summer and the summer tyres during the winter. The storage must be done carefully in order to extend the life of the tyres. There are specialised companies that can store the tyres for you; in most cases, you will be asked to pay a storage fee. You can store your own tyres by following these few steps. Dust out and clean the tyres and then mark them with the position they were removed from - you can use the following code:
  109. LF - left front
  110. RF - right front
  111. LR - left rear
  112. RR - right rear
  113. Please select a cool dry room where there are no traces of gasoline, oil, grease or other chemical substances. You can store the tyres on a wooden pallet.
  114. Suspension

    Suspension refers to the linkages that connects a vehicle to its wheels. Its main function is to permanently connect the wheels to the road and provide the flex to absorb the vehicle's body motion. Wheels can either be connected through an axle or individually supported.
  115. The clutch

    In order for a vehicle to operate without any problems, a separate connection between the engine and the gearbox has to be acheived. This will allow a smoother transition from one gear to another. The clutch is thing that assures this transition. The clutch is the car's component that engages or disengages a transmission of power or a motion. This mechanical device is used by two-shaft mechanisms; usually, one is being driven by a motor while the other one is responsible for the running of the second part of the mechanism. Disabling the torque transmission will make the two shafts to work independently.
    The clutch can be activated while it is rotating or while it stays still. Car clutches can be coupled and uncoupled in a controlled way or in an automatic way. They have a wide range of applications and are useful when changing the gear. The clutch's operating system: one or more clutch discs are pressed between the engine's flywheel and the strong spring pressure plate. Depending on the clutch's type, the friction material may have different compositions.
  116. The life of a tyre

    The life of a tyre depends on the car, the driving style and on other factors. On front wheel drive cars, the front tyres can wear down three times faster than the rear tyres.
    The legal minimum tread depth is 1.6 millimeters.
  117. The pressure plate

    The pressure plate is a component of the clutch. Connects (or disconnects) the engine - Flywheel - with the gear box.
  118. The sidecar

    The sidecar has a metal attachment to the lower side of a motorcycle. It is used to carry goods or people. The sidecar has only one wheel.
  119. Tow bar for PKW

    It serves as a link between the trailer and the vehicle. The couplings are tighten to the correct torque setting and are subject to the limitation of the Road Traffic Licensing Regulations and must be registered in the vehicle registration document. Later on, removing the tow bar from the vehicle must be carried out by a recognized testing station and registered in the vehicle documents.
  120. Tread

    This refers to the part of the tyre that makes the contact with the road.
  121. Tyre coating

    Also known as the “carcass”, the tyre casing is responsible for the tyre’s build integrity and cohesion. It is made of synthetic components. A protective rubber coating that will be gradually worn off the tyre’s tread area during normal driving, so allow the tyre to run-in for the first 50 miles (80 km) to break this glaze and provide maximum grip.
  122. Tyre cord fabric

    The tyre cord fabric consists of several elements whose purpose is to reinforce the tyre. They can be made of nylon, polyester or artificial silk. The fabric that results is inserted into the tyre. The fabric’s design determines the tyre’s type: cross-ply, bias-ply or radial.
  123. Vehicle axles

    Axles are moving parts, increasing or decreasing the traction strength. Regarding vehicles, axles are always the wheels' final connection. When it comes to rear-wheel drive (RWD) axle traction, the drive shaft is the connection between differential and the wheels. A steel bar that only allows movement in a longitudinal direction when it comes to independent suspensions. When it comes to vehicles with front-wheel drive (FWD), the axles are divided in what are known as "constant velosity joints" that are influenced by the wheels' steering angle. With all-wheel drive (AWD) or 4x4 vehicles that are being driven on very slippery surfaces, or off-road, it is not recommended to start driving at high speed; you should only use the minimum necessary speed in these conditions, because axles may otherwise fail by either cracking or breaking.
  124. Wheel balancing

    Wheels are balanced by adding weights to the wheel's rim flange in order to have a vibration free and smooth ride. Unbalanced wheels lead to excessive wear on the tyres, bearings and suspension. This results in uneven vibrations of the wheels and makes the vehicle unstable. The contact with the road is reduced and the tyres "bounce". This leads to the tyres and the shock absorbers wearing out more quickly. Static balancing involves using counterweights on the outer wheel rim edge or flange. The dynamic balancing of the wheels also involves using appropriate counterweights, but at varying positions on both the outer and inner wheel flanges.
  125. Wide tyres

    There is not a clear definition for these type of tyres. Usually, the profile height of these tyres is 55 or lower (for example 205/55 R16). They are also know as "low profile". Advantages of using this type of tyre are: significant increase in the vehicle’s stability, better steering precision, it allows the use large brakes of a higher grade of braking system, improved stability, higher speed etc.

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