The load index and speed rating are the final numbers and letter in your tyre size, for example the "91V" in 205/55 R16 91V. The load index is the maximum weight the tyre can safely carry; the speed rating is the maximum speed it's designed for. Fitting a tyre rated lower than your car needs is unsafe and can fail the MOT, so these aren't numbers to ignore.
Load index
The load index is a code that maps to a maximum weight per tyre. For example, 91 corresponds to 615kg per tyre, while 95 is 690kg. Heavier vehicles, vans and EVs need higher load indices, which is exactly why many EVs and SUVs use reinforced tyres. The index is set so that all four tyres together can carry the car's fully laden weight with a safety margin, so dropping below the specified figure removes that margin. Always match or exceed the index your car's handbook specifies, never go below it.
Speed rating
The speed rating is a letter representing the tyre's maximum design speed:
| Letter | Max speed |
|---|---|
| T | 118 mph |
| H | 130 mph |
| V | 149 mph |
| W | 168 mph |
| Y | 186 mph |
The rating isn't a licence to drive that fast, it reflects the tyre's construction and heat tolerance. Always match or exceed your car's specified rating, because a tyre run near its speed limit builds far more heat, and a tyre rated below the car's design speed is both unsafe and an MOT concern.
What XL and Reinforced mean
You'll often see "XL" or "Reinforced" on a sidewall. Both mean the same thing: an extra-load tyre built with a stronger casing to carry more weight at a given size than a standard tyre. They're commonly specified for vans, SUVs, people carriers and EVs, all of which are heavier than an equivalent ordinary car. If your car came with XL tyres, fit XL again, because a standard tyre of the same size may not have the load capacity the car needs. The handbook and the original tyres tell you what's required.
Why it matters
An under-rated tyre can overheat and fail under load or at speed, and your insurer may treat an incorrectly rated tyre as a modification or as making the car not roadworthy. The tyre safety rules (GOV.UK) require tyres suitable for the vehicle and its use. When in doubt, use the rating on your existing tyres or the door-sill placard, and read our full sidewall markings guide. We always fit the correct load and speed rating for your vehicle, checked against your registration. Book a mobile fit across the UK.
