A tyre speed rating indicates the maximum speed a tyre is legally approved for.
For more information on what the rest of your tyre label means read our extensive guide to buying a tyre, here.
Be that as it may, it’s essential to recall that the lab can’t reenact each possible condition. Think about your tire’s speed rating as a marker of the item’s capacity under controlled conditions (i.e. completely expanded, vehicle running legitimately, great climate conditions). Your tires’ real speed ability might be not as much as its appraised speed, since it is influenced by variables, for example, expansion, wear, vehicle condition (counting arrangement), driving conditions and the span at which speed is kept up. Speed appraisals don’t make a difference to tires that have been harmed, changed, under-swelled, over-burden or fixed.
Being aware of your tyres’ speed rating will allow you to determine the maximum speed your tyre is capable of safely maintaining, for more information about tyre safety.
A one-letter difference in speed rating equals as much as a 10km/h difference in speed rating.
The system is based around the European use of kilometres, which is why speed ratings in mph are at such unusual increments. The difference between each letter is around 6mph.
Speed ratings are achieved through tests performed by engineers who run the tyre at 6.2 mph steps, in 10 minute increments, until the required speed has been met.
Wider, larger-diameter tyres often have a higher speed rating as they are usually fitted to higher-performance cars therefore, are typically designed to cope with higher speeds.
Z-rated high-performance tyres are rated for speeds in excess of 149mph. Confusingly, W-rated tyres are rated at a higher speed in excess of 168mph. Y-rated tyres are rated in excess of 186mph.
Tyre speed ratings should be matched to the official top speed of your car. If you fit cheaper, lower-speed-rated tyres, it could affect your car insurance.
Some tyre organisations offer vehicle registration number (VRM) tyre-finder services, which will automatically choose the correct tyres, with the correct speed rating, for your car.
Z: 150+ mph