Tyre load index and speed rating explained
8 min readBy Wheel Fit
The short answer In a size like 205/55 R16 91V, the 91 is the load index (maximum weight per tyre) and the V is the speed rating. Never fit lower than the vehicle manufacturer specifies. Fitting higher is usually harmless but rarely worth paying for.
Where to find it
The two characters sit at the end of the size string on the sidewall. Your vehicle's required figures are on the placard in the door shut or in the handbook — not on the tyre currently fitted, which may itself be wrong. How to read a tyre sidewall covers the rest of the markings.
Load index
The load index is a code, not a weight in kilograms. Each number maps to a maximum load per tyre:
| Index | Max load per tyre | Typically |
|---|---|---|
| 82 | 475 kg | Small hatchback |
| 88 | 560 kg | Family hatchback |
| 91 | 615 kg | Saloon / estate |
| 95 | 690 kg | Larger estate, small SUV |
| 100 | 800 kg | SUV, heavier EV |
| 104 | 900 kg | Large SUV, light commercial |
| 109 | 1030 kg | Van |
Multiply by four for the vehicle total, though that assumes even loading, which real life rarely provides. This is why vans need commercial-rated tyres: a loaded Transit puts far more through each corner than a family hatchback — see van tyres vs car tyres.
XL, Reinforced and C markings
- XL or Reinforced — a stronger casing carrying a higher load index at a higher pressure. If your car specifies XL, a standard tyre in the same size is not equivalent.
- C — commercial construction, for vans and light commercials. Often shown as a dual index such as 109/107, for single and twin-wheel fitment.
- HL — high load, a newer category appearing on heavy EVs carrying more than XL at the same size.
Speed rating
| Letter | Maximum speed |
|---|---|
| Q | 100 mph (160 km/h) |
| T | 118 mph (190 km/h) |
| H | 130 mph (210 km/h) |
| V | 149 mph (240 km/h) |
| W | 168 mph (270 km/h) |
| Y | 186 mph (300 km/h) |
The obvious question: why does a UK car need a V rating when the limit is 70? Because the rating is not only about top speed. It reflects how much heat the construction can shed and how the tyre behaves under sustained load. A higher-rated tyre generally has a stiffer casing and responds differently to steering input — which is why the manufacturer specified it as part of how the car handles.
A worked example
205/55 R16 91V
205 — section width in millimetres.
55 — aspect ratio: sidewall height is 55% of the width.
R16 — radial construction, 16-inch rim.
91 — load index, 615 kg per tyre.
V — speed rating, up to 149 mph.
Why mixing ratings is a problem
Fitting below the manufacturer's specification can affect your insurance and will be picked up at an MOT if it makes the vehicle unroadworthy. More practically, mismatched ratings across an axle mean the two tyres behave differently under hard braking — which is exactly when you want them behaving the same.
Our rule: match what the door plate says, and keep both tyres on an axle the same specification. See mixing tyre brands and patterns.
This is where cheap quotes sometimes hide A tyre one load index below specification can be noticeably cheaper, and on a price list it looks like the same size. On a heavy or loaded vehicle that is a genuine safety difference, not a technicality. Check the full size string on the quote, not just the first three numbers.
Winter tyres are the exception
Some vehicles are permitted a lower speed rating on winter tyres, provided a sticker inside the car states the reduced maximum. Check the handbook rather than assuming — see winter, summer or all-season tyres.
Common questions
- Can I fit a higher speed rating than specified?
- Generally yes, and it is legal. It often costs more and can give a firmer ride without any benefit at UK speeds. Fitting the specified rating is usually the sensible buy.
- Can I fit a higher load index?
- Yes, and it is sometimes unavoidable because of what is available in a size. A higher index means a stiffer casing, which can firm up the ride slightly.
- What happens if I fit lower?
- The tyre is operating outside what the vehicle requires. It can invalidate insurance, can make the vehicle unroadworthy, and on a loaded vehicle risks overheating — tyre faults that fail an MOT.
- Does a heavier EV need a different rating?
- Usually a higher one. EVs are heavy and many specify XL or HL construction — see EV tyres.
- Does the spare need to match?
- A space-saver is deliberately different and carries its own speed limit, usually 50mph. A full-size spare should match the car's specification.
Checking what your car needs
Call 07989 606060 with your registration or the size from your sidewall and we will confirm the correct load index and speed rating before anything is ordered. Related: how to read the rest of the sidewall and why van tyres are different.
