Glossary

Tyres on the Drive simplifies the most common tyre jargon.

Glossary of Tyre Terms


The amount of air inside the tyre, measured in either pounds per square inch (psi) or bars. The correct pressure for tyres can usually be found in the vehicle handbook and often on the flap to your petrol tank.
Alignment is a process that ensures that the suspension and wheels, in association with the steering, are in accordance with the manufacturer’s specification for the way the wheels should be pointing.
This is a way of expressing a tyre's height as a percentage of its section width. This figure is always found on the sidewall of the tyre.
Tyre balancing is a process to ensure that when the tyre and the wheel spin, their weight is equally distributed.
Metric unit for air pressure, (1 bar = 14.50326 psi).
A ring of steel wire within a rubber wrapper that helps to hold the tyre to the rim.
This is the skeleton of the tyre sitting underneath the tread and sidewalls.
This is the tyre pressure before the tyre has been able to heat up from driving.
Tyres designed to give better grip below temperatures of 7 degrees. Also known as winter tyres.
The area of the tyre's tread that is in contact with the ground.
In a tubeless tyre, the inner liner prevents air from seeping out of the tyre.
This is a code that ranges from 0 to 279 that quantifies the maximum weight a tyre can bear at the speed indicated by the speed symbol.
A description of tyres that are quite ‘thin’ in comparison to the radius of the wheel.
The maximum pressure that a tyre can be inflated to.
The imperial unit for air pressure.
The outer part of the wheel on which the tyre is mounted.
Distance between the two opposite inside edges of the rim flanges.
The energy needed to keep a tyre moving at a constant speed. A low rolling resistance means less energy is being used to keep a tyre moving.
Run flat tyres enable vehicles with a puncture to be driven at reduced speeds for a limited time until they can be replaced.
The measurement of the tyre from side to side.
Found where the sidewall and tread meet.
The area between the bead and the start of the tread.
Slits in the tread designed to improve grip in wet conditions.
Used to identify a specific tyre. It includes width, construction type, aspect ratio and rim size.
Indicates the range of speeds at which a tyre can carry a load under a range of conditions. Ratings are categorised from A-Z.
Made of a mixture of rubber, chemicals, fabric and metal, their job is to give the car traction on the road in a variety of conditions, and to cushion the car from shock.
Information on the recommended pressure, rim size and load capacity can be found in your vehicle handbook and sometimes on the inside sill of the driver’s door.
The part of the tyre that comes into contact with the road.
Narrow bands in the tread grooves that provide a visual warning as to when a tyre needs changing, since they can only be seen if the tread has worn below the 1.6mm threshold.
Tread width is the portion of the tyre's width that is covered by a tread pattern.
The condition that exists when there is not sufficient air pressure in a tyre.

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