What is a tire load rating and what is a tire speed rating? Do they have to be respected when replacing tires? Find the answers to your questions in this article.
What are tire ratings?
The sidewall of your tire has various alphanumeric markings that allow you to understand a number of things about it. (Learn how to read tire markings)
Part of this coding is the tire load rating and the tire speed rating, which are indicated by a number and a letter respectively.
There may be tire ratings written in your car owners manual or on the sticker in the driver's door. This information describes the tires recommended by your vehicle manufacturer.
What do these tire ratings mean? Do you have to comply with them when you replace your tires? We will discuss this in this article.
Tire load rating
What is the tire load rating?
The tire load rating is a numerical code which corresponds to a maximum load (in kg) that can be carried by a single tire. The load rating and corresponding maximum tire loads are listed in a standard table.
To identify the maximum load your tire can carry, or the load index recommended by your vehicle manufacturer, simply do the following:
1 - Find the tire load rating
On the sidewall of your tire, 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 tires. They indicate the tyre dimensions, load and speed ratings.
Let's see what this coding means:
Tire load rating
Tire speed rating
Note that tires of the same dimension can have different tire load and speed ratings. This is why it is important to understand the dimension, tire speed and tire load rating before replacing tires.
In this example, the tire load rating is 91.
2 - Tire load rating chart
Once you have noted the tire load rating, you can find the maximum single tire load that it refers to by consulting this table:
In our example, we see that the tire load rating of 91 corresponds to a maximum tire load of 615 kg.
What does XL mean on tires?
Some tires are also marked XL. This stands for "Extra Load".
It simply means that the tire has been reinforced to be able to carry heavier loads than standard tires of the same dimension. This type of tire is generally used on heavier vehicles, for example SUVs .
Can I switch to a tire with a higher load rating ?
As mentioned above, tires of the same size can have different load ratings. When replacing worn tires, it is recommended that tires 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 tires 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 tire 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 tire.
Tire speed rating
What is the tire speed rating?
The tire speed rating indicates the maximum speed at which a tire can carry its maximum load.
On the sidewall of your tire (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 tire speed rating is V.
Tire speed rating chart
To find out what speed this index corresponds to, simply refer to the tire speed rating chart below:
For example, if the tire has a speed rating of V, then the maximum speed it can sustain is 149 mph (240 km/h).
Can I switch to a tire with a higher speed index?
When your tires are worn out, it is perfectly possible to replace them with tires with a higher speed index than the one indicated on the old ones. However, you should never mount tires with a lower speed index unless fitting tires with winter capacities such as winter tires or All Season Tires, as discussed below.
Choosing a lower speed index for winter tires
If you use tires with winter capacities (marked 3PMSF : either winter tires or All Season Tires), the speed rating may be lower than that of your summer tires or the original tire fitted to your vehicle.
Why is this possible? Tires 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 tires. In the UK the speed rating of tires 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 tire.
Simplified tire load ratings and speed ratings with MICHELIN’s CrossClimate range
Faced with an offer that has become complex and diversified, Michelin has chosen to simplify with its MICHELIN CrossClimate all-season range, which offers a single load and speed rating for each dimension of tire which covers all of the normal load and speed requirements of tires of that dimension.
MICHELIN CrossClimate range offers you excellent performance in both winter and summer.