A Complete Guide To Tyre Speed Ratings
As a car owner, it’s important to understand tyre speed rating, load index, and tyre size. When it comes to buying new tyres, you can’t live without this information – understanding tyre speed ratings and how they affect which tyres you can use on your car is essential.
Tyres have their size, speed rating, and load index labelled on their sidewall. Knowing how to read this information is one thing, but knowing what each marking actually means is another. This blog will help you to understand tyre speed rating so you can choose the right tyres for your car.
What is tyre speed rating?
Tyre speed rating is the maximum speed that the tyre is legally approved to be driven at, based on the recommended load index that’s also on your tyre. These speed ratings are based on practical tests that engineers run when new tyres are designed – making sure the tyres can safely reach high speeds.
Can speed rating affect my driving?
The best quality tyres have better braking, grip on wet roads, and more responsive steering. If you use tyres with the wrong speed rating, it could contribute to dangerous driving as steering response will undoubtedly be affected. Installing the wrong type of tyres on your car can also void the manufacturer’s guarantee, so be sure to check in your user manual.
It’s possible that your insurer will refuse to pay out if the wrong tyres have been selected, or that you will be fined by a police officer for having unsafe tyres. In the worst cases, the wrong speed rating can cause a tyre blowout or serious accident.
To ensure that you’re buying high quality tyres, look out for ones that are labelled with EU tyre labels. These provide improved tyre information for buyers through a rating system that covers fuel efficiency, braking distance in wet conditions and exterior noise, making tyres with these labels ideal for long-distance motorists.
How to read the tyre speed index
The tyre speed index is a system that indicates the maximum speed that your tyre is legally approved for. The system is based on a lettered code and each letter corresponds to a speed. The tyre speed rating is clearly displayed on the sidewall of each tyre and indicates the fastest speed that a driver should not exceed when their vehicle is fitted with those specific tyres. The speed rating numbering system run from A1 to A8 in sequence, whilst the letters run from B to Y.
For example, a tyre that reads 255/40 R20 101V shows V to be the tyre speed rating. As seen in the tyre speed rating chart below, V corresponds to 149 mph. Therefore, tyres with this speed rating should not be driven over 149mph.
Tyre speed rating chart
What tyre speed rating do I need?
Most vehicles fit into the speed rating of S or T for 112 or 118 miles per hour limits (180 or 190 kilometres per hour). The speed ratings for wide diameter tyres are often higher as they are usually fitted to higher-performance vehicles. Sports cars need tyres with speed ratings of W, Y or (Y).
If you decide to choose tyres that are an incorrect speed rating, load index or size for your car, you must inform your insurance company, as it is likely to affect what you are entitled to claim in the event of an accident. At Tyre Shopper, we recommend that you keep speed rating in mind when choosing new tyres.
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