Looking after your vehicle means making sure it is safe and comfortable to use. Checking the parameters of your vehicle’s tyres is an important step that shouldn’t be overlooked, and the tyre load index is just one aspect that will need to be investigated before investing in replacement tyres.
What is the tyre load index?
A tyre load index describes the maximum load, or weight, that an individual tyre is able to safely carry when inflated to the safe, recommended tyre pressure. Different makes and models of tyres have different tyre load indexes, which is detailed on the sidewall – usually it is displayed as a two or three digit number that follows the numbers describing the dimensions of the tyre.
The width of your tyre, in millimetres, measured from sidewall to sidewall.
This is the ratio of the tyre’s cross-section to its width, expressed as a percentage. An aspect ratio of 65, for example, indicates that the tyre’s height is 65% of its width.
The diameter (height) of the wheel in inches.
Your tyre’s load index relates to its maximum carrying capacity (in kg). You’ll find the load rating of your tyre on the sidewall, just to the right of the diameter. For example, a tyre with a load index of 91 can carry 615kg of weight. Load ratings and speed ratings should be looked at together when you buy a new tyre. Also remember to check your manufacturer’s recommendations.
The speed rating is the maximum speed for a tyre when it is correctly inflated and being used under load. The speed rating is the letter at the end of the sidewall, after the load index number. A tyre with a speed rating of V, for example, has a maximum speed of 240 km/h. When buying new tyres, make sure you match their speed rating with the speed capabilities of your vehicle.
Why is the tyre load important for drivers?
Overloading tyres can be unsafe and lead to tyre damage. You must ensure that a tyre with a suitable load index is fitted to your vehicle – never affix tyres that have a lower load capacity than recommended.
Recommendations can usually be found in your vehicle handbook, which should detail the appropriate range of load indexes that any new tyres will need, in relation to your specific vehicle. Failure to heed this advice could lead to the fitting of a tyre with an incorrect load index, which could cause problems with insurance, and may even invalidate certain policies.
How to use the tyre load index
To the right you will find our handy tyre load index chart which outlines the maximum weights attributed to each load index rating – highlighting exactly how much weight a tyre can safely carry. To calculate the total carrying capacity for your car as a whole, simply multiply the single tyre load index by four.