For example, if the tyre has a speed rating of V, then the maximum speed it can sustain is 149 mph (240 km/h).
Can I switch to a tyre with a higher speed index?
When your tyres are worn out, it is perfectly possible to replace them with tyres with a higher speed index than the one indicated on the old ones. However, you should never mount tyres with a lower speed index unless fitting tyres with winter capacities such as winter tyres or All Season Tires, as discussed below.
There are specific cases for W, Y and (Y) speed ratings, which are specific to high-speed vehicles (> 270km/h). If you are concerned, please ask your dealer for advice.
Simplified sport ranges
As we said earlier, "who can do more can do less". With this in mind, we've simplified our Sport ranges, such as the MICHELIN Pilot Sport4, MICHELIN Pilot Sport4S and MICHELIN Pilot Sport 5, to make it easier for consumers to find their way around.
Most of the sizes in these ranges now have HIGHER possible load ratings than the original ones in order to meet all requirements.
Here's a concrete example:
If your original tyre size is 225/45 R17 91 V, you can opt for size 225/45 R17 94 Y.
The 94 load index means that the tyre is capable of carrying a higher load (up to 670 kg) than your original tyre (up to 615 kg). A tyre of the same size with a higher load index is therefore perfectly compatible.
The speed rating is also compatible if it is higher.
Choosing a lower speed index for winter tyres
If you use tyres with winter capacities (marked 3PMSF : either winter tyres either All Season Tyres), the speed rating may be lower than that of your summer tyres or the original tyre fitted to your vehicle.
Why is this possible? Tyres 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 tyres. In the UK the speed rating of tyres 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 tyre.