What are tyre ratings?
The sidewall of your tyre has various alphanumeric markings that allow you to understand a number of things about it.
Part of this coding is the tyre load rating and the tyre speed rating, which are indicated by a number and a letter respectively.
There may be tyre ratings written in your car owners manual or on the sticker in the driver's door. This information describes the tyres recommended by your vehicle manufacturer.
What do these tyre ratings mean? Do you have to comply with them when you replace your tyres? We will discuss this in this article.
Tyre load rating
What is the tyre load rating?
The tyre load rating is a numerical code which corresponds to a maximum load (in kg) that can be carried by a single tyre. The load rating and corresponding maximum tyre loads are listed in a standard table.
To identify the maximum load your tyre can carry, or the load index recommended by your vehicle manufacturer, simply do the following:
1 - Find the tyre load rating
On the sidewall of your tyre, you will find a string of numbers and letters that look like this:
You may also find them on the sticker on your driver's door or your vehicle owner’s manual.
These numbers and letters vary between tyres. They indicate the tyre dimensions, load and speed ratings.
Let's see what this coding means:
Tyre load rating
Tyre speed rating
Note that tyres of the same dimension can have different tyre load and speed ratings. This is why it is important to understand the dimension, tyre speed and tyre load rating before replacing tyres.
In this example, the tyre load rating is 91.
2 - Tyre load rating chart
Once you have noted the tyre load rating, you can find the maximum single tyre load that it refers to by consulting this table:
In our example, we see that the tyre load rating of 91 corresponds to a maximum tyre load of 615 kg.
What does XL mean on tyres?
Some tyres are also marked XL. This stands for "Extra Load".
It simply means that the tyre has been reinforced to be able to carry heavier loads than standard tyres of the same dimension. This type of tyre is generally used on heavier vehicles, for example SUVs .
Can I switch to a tyre with a higher load rating ?
As mentioned above, tyres of the same size can have different load ratings. When replacing worn tyres, it is recommended that tyres with the original manufacturer’s load rating (and speed rating), as well as the original dimensions, should be fitted.
Anyway “who can do more can do less” and it is of course possible to fit your car with tyres that have a higher load rating than the manufacturer’s specification. However, you will not necessarily be able to carry more load than the original manufacturer’s specification because there is a limit on the maximum permissible axle load for your vehicle, independent of the tyre load capacity.
What about the size? Is it possible to change it?
You can find the answer to this question in our article on changing the size of a tyre.
Tyre speed rating
What is the tyre speed rating?
The tyre speed rating indicates the maximum speed at which a tyre can carry its maximum load.
On the sidewall of your tyre (or the sticker in the driver's door, or the owner’s manual), the speed rating is defined by a letter right next to the load rating
Here, the tyre speed rating is V.
Tyre speed rating chart
To find out what speed this index corresponds to, simply refer to the tyre speed rating chart below:
For example, if the tyre has a speed rating of V, then the maximum speed it can sustain is 149 mph (240 km/h).
Can I switch to a tyre with a higher speed index?
When your tyres are worn out, it is perfectly possible to replace them with tyres with a higher speed index than the one indicated on the old ones. However, you should never mount tyres with a lower speed index unless fitting tyres with winter capacities such as winter tyres or All Season Tires, as discussed below.
Choosing a lower speed index for winter tyres
If you use tyres with winter capacities (marked 3PMSF : either winter tyres or All Season Tyres), the speed rating may be lower than that of your summer tyres or the original tyre fitted to your vehicle.
Why is this possible? Tyres with winter capacities are designed differently for driving in difficult climatic conditions (snowy, icy roads, etc.) and may not have the same speed rating.
However, generally you drive at a lower speed in winter than you would on dry roads with summer tyres. In the UK the speed rating of tyres with winter capacities will still be in excess of the national speed limit. In any case, the driver must limit the speed of the car so not to exceed the maximum speed of the tyre.