Important tyre terms

Posted by: Cal on 28/08/2014

Category: Tyre Information

When you are selecting the best set of new car tyres, you will in no doubt be looking for good tread, grip and durability.

If these are the only tyre terms you are aware of, it may be time to inflate your car vocabulary. Here are some other important words that mean something different where it comes to these car parts.


Wondering what the outside wall of your tyre is called? This part will affect how well your tyres are able to perform under a heavy load. 


The bead refers to the innermost edge of the tyre where it reaches the rim of the wheel.

This area is usually reinforced with steel wires that are embedded into the rubber. These are designed to hold the tyre to the wheel and prevent damage caused during installation and removal. 


Your car's shoulder refers to the area where tread meets the sidewall. 

Contact patch

This one may be a little self-explanatory, but refers to the area where your car tyre touches the road. The amount of tyre that touches the road is based on your tyre pressure. If your tyres have low pressure, the contact patch will be bigger. This can make your tyres wear more quickly.

This is also known as the tyre's footprint. 


This word refers to the amount of weight that your tyres bear. A truck tyre will have a larger load than a car tyre as it carries a heavier cargo. 

If you are planning to carry a heavy load, then you will need to make sure your car tyres have more grip.

The load may shift however, as it moves to the side when you corner, to the back when you accelerate and to the front when you brake.

Load index

Your tyres will also feature a load index that reveals how many kilograms your tyre can support. This measurement is based on a properly inflated tyre. A numbering system is used to indicate this amount, but if this is not clear, you can look elsewhere on the sidewall to find out how many kilograms can be carried.


Your front tyres may point out when you look at them from above - especially if you own a racing car! If your tyres face inwards, this is known as being 'toe in' while tyres that point towards each other to a point behind your car are known as 'toe out' tyres.


If your tyres get excessively hot and parts of it begin to melt and bubble, this is known as a blister. 

This is a sign you need to head online to buy new tyres as it means a compound in the tyre is breaking down. Your tyres may become oily and lose grip on the road.

It is important to check your car tyres weekly to ensure there are no signs of excessive wear and tear.

Aspect ratio

According to AutoGuide, the aspect ratio can also be known as the tyre profile or series ratio. This is essentially a measurement of the height of the tyre from the bead to the tread. This can be calculated by dividing the section height by the width.

A tyre with a lower aspect ratio will generally have a shorter and stiffer sidewall so it will better resist cornering forces and have an improved lateral stability. 

Flat spot

Excessive braking can cause a flat spot in your tyres. This means there will be heavy wear on that area. If you spot this, it may be time for new tyres as it can result in poor handling or diminished tread.

You may notice severe vibration if you have a flat spot and this can be dangerous as well as uncomfortable.