A guide to help you make sense of the writing on your tyre sidewall
Have you ever noticed the numbers and letters on the tyres of your car and wondered what they meant? These markings can seem complicated if youíre not familiar with them, but they have an important function.
Much like an EU tyre label, these codes are there to provide useful information to motorists about the size, pressure, load rating and other manufacturer details of the tyre. When buying new tyres, these number and letter sequences can have a significant effect on the safety, performance, fuel efficiency and environmental impact of the vehicle, so itís worthwhile finding out what they mean.
On the sidewall of the tyres, you can find a tyre size guide. It contains a series of letters and numbers. To locate the tyre size, it is likely the largest text printed on the tyre sidewall other than the names of the manufacturer and tyre model. There are multiple different tyre sizes, so itís vital to make sure that you check these markings or consult your vehicleís handbook to be sure you have the right size before choosing replacement tyres.
The first three figures in the sequence represent how wide the tyre is in millimetres across the tread. The next two digits indicate the profile height of the sidewall. Most tyres will also be branded with the letter R, which means radial. Radial tyres are made in a way that gives them added strength. The final two digits indicate the dimensions of the wheel rim that the tyre is fitted to. The tyre size always appears in this uniform order so thereís no confusion when choosing new tyres.
The tyre load index is another important consideration as it determines how much weight a tyre can carry. This is shown as a sequence of numbers located after the size code and ahead of the speed rating. You can also check the vehicle handbook for a complete tyre load index guide. Larger vehicles or vehicles used to transport heavy loads may require tyres with a higher load index in order to comfortably support this additional weight. Find out the weight limit of your tyre by entering its load index rating.
The tyre speed rating guide is expressed as a letter and can be found after the size code. This represents the maximum speed the tyre is capable of. While the speeds indicated may seem quite high, we do not recommend replacing tyres with a lower speed rating than your existing tyres and this could also invalidate your insurance. If you are unsure of what tyre speed rating you require, you can find this information in your handbook for your vehicle as recommended by the manufacturer. Find out the maximum speed of your tyre by entering its speed rating.
Tyres with an increased load index are marked to show that they have been reinforced to handle extra weight. These markings vary with each manufacturer and can include symbols such as XL and EXL to mean extra load, or RF, REINF or RFD to show they are reinforced.
Run flat tyres are specially designed with additional strength sidewalls so that if the pressure starts to decrease after a puncture, they can temporarily carry the weight of the vehicle until you are able to safely pull over and replace them. Run flat tyre markings are indicated by symbols such as ROF, EMT, RFT, ZP, SSR or DSST, depending on the manufacturer. Run flat tyres should only be fitted to vehicles with Tyre Pressure Monitoring Systems (TPMS) that monitor tyre pressure as you drive.
Having the right tyre pressure can extend the life of your tyres, increase the safety of your vehicle and help to improve fuel efficiency. The maximum pressure inflation can usually be found on the sidewall of a tyre. However, a full tyre pressure guide will be specified in the manufacturer's handbook and itís up to you as the driver of the vehicle to regularly check to ensure they are the correct pressure. This should be done every few weeks or so with a pressure gauge and only when the tyres are cold.
OE (Original Equipment) tyres are unique versions of regular tyre models that have been developed and tuned to the individual performance requirements of the vehicle manufacturer. Each manufacturer has a different unique identifier that is printed on the tyre sidewall to show that the tyre has been designed specifically for the vehicle. Examples include M0 for Mercedes, a Star for BMW, R01 and A0 for Audi and K1 or K2 for Ferarri. TyrePlus stocks a range of OE tyres Ė look out for the vehicle manufacturer's OE symbol next to relevant tyre products.
Details of where and when the tyre was manufactured may also be written on the tyre, which is represented by a sequence of letters and numbers starting with the letters DOT (Department of Transport). This can help to give you an idea of how old the tyres are and determine whether they are safe to use on the roads. You can find the date of manufacturer of a tyre in a small 4-digit window. The first two digits represent the week of the year the tyre was made, the last two digits represent the year. So a tyre marked 4216 was manufactured in the 42nd week of 2016. As tyres get older the compound they are made from can deteriorate resulting in cracking on the sidewall and distortion of the tread. We recommend having your tyres checked professionally if they are more than 6 years old.
As well as regular tyre markings, all new car and van tyres come with a printed label stuck to the tread which is designed to tell you how well the tyre performed in independent tests. When choosing new tyres, itís also a good idea to check the EU label for other important details such as fuel efficiency, wet grip and exterior noise. Click the button below to find out more about the EU tyre label including more information on the performance categories in which the tyre is assessed.More Info
Itís worth bearing in mind that while it may not be illegal, itís not advised to choose tyres with a lower speed rating or load index than recommended by the manufacturer. Itís also not recommended for a vehicle to have different types of tyres. This is because the wrong type of tyres can invalidate your insurance and increase the risk of a road accident. You should also remember that the speed index and other factors may differ for summer and winter tyres.
If youíre struggling to choose the right tyres, weíre here to help. Simply add your vehicle registration number to the search bar below to find the advisable versions for your vehicle.
We offer a wide range of tyres at competitive prices, with a network of over 700 fitting locations across the UK and Northern Ireland. Our team of experts can help you find the most suitable tyres for your car to ensure maximum safety and performance.