Blackcircles.com Tyre Glossary T-Z
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Traction: A term used to describe the force of friction between the drive wheel and the road
Tread: This is the part of the tyre that comes into contact with the road.
Tread Depth: The measurement between the top of the tread runner to the tyres deepest grooves. The legal limit for tread depth is a minimum of 1.6mm
Tread Wear Indicator: These are narrow bands in the tread grooves which provide a visual warning when tyres need changing. These become visible if the tyre falls below the legal limit of 1.6mm
Tubeles: usually a radial tyre these are constructed with an inner liner to protect against loss of pressure during normal use
Tyre Compound: Tyre information: Found in the vehicle handbook or sometimes of the inside sill of the driver’s door, this information outlines the recommended pressure, rim size and load capacity A "mix" or combination of raw materials used in the manufacture of the rubber compound of the tyre itself. By varying the percentage or the composition of the materials applied, manufacturers can produce different tyres for various purposes and with different performances.
Tyre PressureTyre Pressure Monitoring System (TPMS):this device, usually attached in the wheel wall, or to the tyre which can send information to a dashboard display whilst the vehicle is in use. If there is a loss in pressure the driver is alerted. Note: run flat tyres (link) can only be used if a vehicle is fitted with a TPMS: This is the amount of air inside the tyre measured in PSI or in Bar The correct pressure can be found in the vehicle handbook and usually on the inside of the petrol tank flap. This should be changed regularly as tyre pressure reduces gradually over time. Note, tyres should never be inflated beyond the maximum pressure specified in the vehicle manufacturers handbook
Tyre Wall: The area on the tyre where information about the tyre is displayed
Under Inflation: A tyre with insufficient air pressure
Under Steer: When a car fails to respond to drivers steering and continues to drive straight. This is the opposite to Oversteer
Valve: Allows the tyre to be inflated to the correct pressure. Valves are usually made of rubber, with a metal core assembly with a screw on dust cap. There are 2 standards lengths, short for most alloy wheels and long for steel wheels which have a plastic wheel trim
Winter Tyres (also see Cold Weather Tyres ): These Tyres which are constructed using special compounds designed for use in winter driving conditions including temperatures below 7 degrees Celsius. Can include multiple blades (link) or Sipes (link) for increased grip in slippery conditions