Tyre Glossary P-S


a-c     d-o     p-s     t-z     Glossary Home


Plies (or ply): The reinforcing members of a tyre which are composed of layers of cord fabric and rubber that provide the strength to contain the air pressure needed to support a load and resist deflection.

Profile (also see Aspect Ratio): The height of the tyre sidewall expressed as a percentage of the tyres width.

PSI (pounds per square inch): Imperial measurement unit for air pressure.

Radial Tyre: The design of all modern car tyres. Development of the use of parallel carcass belts for sidewalls and crossed belts for the crown of the tyre.

Repairable Area:  Tyre Tread area where a puncture repair can be made to the British Standard BSAU159f .

Reinforced Tyres:  Tyre where the manufacturer has added extra strength by adding more plies into the side wall to handle more weight e.g. for heavier vehicles (i.e. SAAB 9-3s or Ford Galaxy’s Renault Laguna).

Remoulding: A recycling process where a tyre is buffed back to its casing, repaired and rebuilt using a fresh tread compound.

Retreading: This is the process of replacing the tread layer on a tyre. Usually reserved for commercial, agricultural and industrial tyres.

Rim: The metal edge of the wheel on which the bead is seated supporting the tyre.

Rim Size: The diameter of the rim (usually measured in inches and also known as the wheel size).

Rim Width: The Distance between the two opposite inside edges of the rim flanges.

Rolling Resistance: The energy required to keep a tyre moving at a constant speed. The lower the rolling resistance the less energy being used to keep the tyre moving.

Run-Flat: Tyres which allow a driver to continue a journey in the event of low or no pressure. Please note that Run-flats are designed to run for short distances and should be replaced as soon as possible.

Section Height: The height of the tyre from the rim to the outer tread.

Section Width:  Measurement of the tyre from side to side. This measurement excludes raised letters or any other additional sidewall items.

Service description: As well as Tyre Size Designation a tyre may be identified by a Service Description consisting of a load index (or two Load Indices in the case of single/dual fitments) and a Speed Symbol.

Shoulder: This is where the sidewall and the tread meet on the tyre.

Sidewall: This refers to the area between the bead and the start of the tread.

Silica: Reinforcing filler used in a rubber compound to provide higher tyre mileage and lower rolling resistance .

Sipes (also known as Blades): This refers to slits in the tread blocks which are designed to increase grip on winter and wet-weather tyres by moving water away from the tyre.

Snow Tyres: Tyres specifically designed to perform better in the snow.

Space Saving Tyre (also known as a “Mini” tyre): Smaller than the road tyres, this type of Tyre is designed to save space and reduce weight in the vehicle. A temporary measure to get you home these tyres should be changed as soon as possible, these tyres also have a lower maximum speed.

Speed Rating: The standardised index which is used to indicate the maximum speed a tyre can sustain carrying the specified load.

Specified load: Found in the load index under the conditions specified by the tyre manufacturer.

Steel rimmed wheels: The standard fit wheel for most cars, can be upgraded to alloy wheels.

My basket

My Products:

Your basket is empty - please choose your tyres.

Click here toCHOOSE TYRES

Share on facebook  Share on twitter

Connect Us