Tyre glossary

Tyre Glossary

Tyres can seem like such a simple thing, black round rubber right?  Well yes and no.

At Premiorri Trading we appreciate that you may not understand some of the words and phrases used when it comes to a visit to your local tyre fitter, so we have put together a tyre glossary to help you to feel more confident the next time you need to discuss your tyres.


This is in relation to your wheels and is sometimes referred to as tracking.  Aligning your vehicles wheels is a process undertaken to ensure that your vehicle drives in a straight line.  Alignment can be affected by driving over pot holes or going up a kerb.  If you experience vibration or juddering through your steering wheel or notice uneven tyrewear, we would suggest that you talk to your local tyre expert.  

All Season Tyres

All season tyres are relatively new to the tyre market and have been designed specifically to work well in both the summer and winter months where conditions can vary.  A specialist rubber compound is added at the point of manufacture and the tyre tread pattern will differ to either summer or winter tyres.

Aspect Ratio

When thinking of tyres, the aspect ratio is the tyres height as a percentage of its width. This measurement is found on the sidewall of your tyres.  


This is a ring of wire steel that helps to hold the tyre to the rim


A tread block is part of the tyre tread pattern, they can be different shapes and are what tyre manufacturers use to create tyres suitable to specific driving requirements.


The tyre casing is the actual tyre which is made up of all components, you may be charged by other retailers for casing disposal, this is included in the cost of our tyres.


A mixture of materials used to construct tyres is known as a compound which can differ depending upon the manufacturer and the tyre type being made. An example of this is a summer tyre or a winter tyre, both will have a different compound, depending upon their required use.

Load Index

The load index can be viewed on the sidewall of your tyre and indicates the maximum weight that the tyre can carry at a certain speed. 



Pressure refers to the inflation of a tyre and is measured in PSI (pounds per inch) or bar.  When inflating your tyre, your vehicle manufacturer will have recommended the pressure that your tyre should be inflated to both when empty or fully loaded.

Reinforced Tyres

Tyres that need to carry a heavy load are likely to be fitted with a reinforced tyre.


This refers to the edge of your wheel, and helps to hold the tyre in place.

Rolling Resistance

Rolling resistance is referred to when a tyre is rotating against a surface (a road) and kept at a constant speed.  The less resistance a tyre encounters, the better for your pocket as the tyre will be more fuel efficient.



The sidewall of the tyre is the most visible area and contains all of the information required to identify your tyre size.


This can be used as part of the compound for manufacturing tyres and can be used to regulate the treadwear when in use.

Speed Rating

The speed rating of a tyre indicates the maximum speed limit at which a tyre can be driven and can be found on the sidewall of your tyre.

Summer Tyres

Tyres designated as summer tyres have been designed for excellent performance during the summer season where temperatures regularly stay over 7 degrees C.  


The tyre tread is the patterned part of the tyre that is in contact with the road surface.  Tread patterns differ for each manufacturer or tyre type and are used to enhance the performance of a tyre, for example a good tyre in the wet will have a tread that disperses water well.

Tyre Size

All vehicles have a recommended tyre size which is a combination of different measurements including the Width, Profile, Diameter, Speed Rating and Load Index

Winter Tyres

Tyres designated as winter tyres have been designed for excellent performance during the cold season where the temperatures regularly drop below 7 degrees C. They are manufactured with compounds that respond better in cold weather conditions.