Tyre Glossary
Buying new tyres can involve a lot of tyre terminology that many people simply don’t understand. To help you make a more informed tyre purchase, we have compiled a glossary of the more commonly used tyre terms.
All Season Tyres – Tyres which have been constructed with a tread pattern and compound to provide satisfactory performance in all weather conditions. Find out more about all season tyres.
Aquaplaning – The term given when tyres lose contact with the surface of the road due to a layer of water. Aquaplaning is more likely to occur when tyres have low tread depth and cannot properly grip the road.
Bead – A combination of rubber band and steel ring which holds the tyre to the rim of the wheel. This is crucial to the tyre as it prevents the tyre from slipping when the wheel rolls.
Blocks – Rubber shapes in the tyre tread which make up the pattern design of the tyre. Blocks can differ in shape and size depending on the tread pattern of the tyre.
Braking Distance – This is the distance it takes for a vehicle to come to a complete stop after the brakes have been applied.
Carcass – The internal skeleton of the tyre made up of cords and plies to give the tyre its shape and structure. This is covered by the tyre tread and sidewalls.
Comfort – A tyre’s ability to absorb driving shocks caused by friction from general driving. The lower the driving comfort, the more you will be able to feel bumps and potholes in the road.
Compound – The mixture of materials, such as rubber and carbon, that are used to construct tyre tread. Different mixtures are used to create tyres for different purposes for example winter tyres will use a compound that will not stiffen in cold temperatures.
Contact Patch – Also known as the footprint of the tyre, the contact patch is the area of the tyre that is in contact with the surface of the road.
Grooves – The series of spaces between blocks moulded in the tyre tread which are shaped for purpose by the manufacturer. The primary purpose of grooves is to provide grip and channel water away from the tyre.
Load Index – The figure which refers to the maximum weight or load a tyre can carry when travelling at its maximum speed. This is specified by the tyre manufacturer and can be found on the tyre sidewall.
Noise Level – The noise that a tyre creates when driving expressed in decibels. This is measured by the EU Tyre Label and is displayed with one, two or three sound waves to express how much noise pollution it creates.
Original Equipment [OE] – The tyre which was originally selected by a car manufacturer for a vehicle model. There can be more than one original equipment brand fitment per vehicle.
Performance – Relating to a tyre’s braking, accelerating and handling capabilities, performance implies how the tyre drives.
Reinforced Tyres – Often used by transportation vehicles that carry heavy loads, reinforced tyres are built with extra strength to help handle weight and stress.
Rolling Resistance – The energy that is required to keep the tyre moving at a constant speed. Lower rolling resistance means that less energy is required for the tyre to move, which means that less fuel is required.
Run-Flat Tyres – Tyres which are constructed with a reinforced sidewall to enable motorists to continue to drive for a short distance following a puncture or other tyre damage on the road.
Shoulder – The area of the tyre between the tyre tread and sidewall.
Sidewall – The rubber side of the tyre that protects the carcass and sits between the tyre tread and the bead. There is important tyre information printed on the sidewall of the tyre.
Sipes – Small slits located on tread blocks which are designed to improve grip and traction in wet conditions.
Space Saver Tyre – A spare tyre which is slightly smaller in size and weight to reduce vehicle load. This type of tyre can be fitted in case of tyre damage, however, it is designed to run only for a short distance at a reduced speed.
Speed Rating – This figure indicates the maximum speed that a tyre can run at as specified by the vehicle manufacturer. This is located on the tyre sidewall.
Summer Tyres – Constructed with specialist tread patterns and compounds to provide superior performance in temperatures over 7°c. Find out more about summer tyres.
Tyre Pressure – The amount of air inside your tyre as measured in PSI (pounds per square inch) or bar. Keeping your tyres at the correct pressure is vital for optimal road handling and better fuel efficiency. Learn more about tyre pressure.
Tyre Tread – The external rubber part of the tyre which is in contact with the road. Tyre tread provides grip and resistance against aquaplaning and will wear with use so it is important that you check it every three weeks. Find out more about tyre tread depth.
Wheel Alignment – A process which ensures that wheels are positioned to the correct angle to provide optimal driving performance. These angles will be specified by your vehicle manufacturer and can be affected by adjustments to your tyres, steering or suspension or by hitting a kerb or pothole. Learn more about wheel alignment.
Wheel Balancing – The process of equalising the weight of your wheel and tyre with small weights to ensure that the tyre remains in constant contact with the road as it rotates.
Winter Tyres – Tyres designed specifically to perform in cold temperatures and wet or snowy conditions. They are constructed with specialist tread patterns and compounds to provide superior winter performance. See more about winter tyres.
