The load index is the number near the end of a tyre size, just before the speed rating letter. It is a code for the maximum weight one tyre can safely carry at its correct pressure. In a size ending 91V, the 91 is the load index, and on the standard chart it equals 615kg per tyre.
Why it is a code, not a weight
Rather than print a weight in kilograms on the sidewall, tyre makers use a short numerical code that maps to a weight on a fixed international chart. This keeps the sidewall marking compact and consistent worldwide. The trade-off is that the number means nothing on its own until it is read against the chart.
The figure applies to a single tyre. Multiplied across all four, it comfortably exceeds the weight of the car plus passengers and luggage, which is the safety margin built into the system. Commercial and van tyres work a little differently, carrying a dual load index that gives separate figures for single and twin-wheel fitment.
The load index chart
The most common car, SUV and van values are shown below. Each step up the index is a meaningful increase in carrying capacity.
| Index | kg | Index | kg | Index | kg |
|---|---|---|---|---|---|
| 75 | 387 | 89 | 580 | 103 | 875 |
| 76 | 400 | 90 | 600 | 104 | 900 |
| 77 | 412 | 91 | 615 | 105 | 925 |
| 78 | 425 | 92 | 630 | 106 | 950 |
| 79 | 437 | 93 | 650 | 107 | 975 |
| 80 | 450 | 94 | 670 | 108 | 1000 |
| 81 | 462 | 95 | 690 | 109 | 1030 |
| 82 | 475 | 96 | 710 | 110 | 1060 |
| 83 | 487 | 97 | 730 | 111 | 1090 |
| 84 | 500 | 98 | 750 | 112 | 1120 |
| 85 | 515 | 99 | 775 | 113 | 1150 |
| 86 | 530 | 100 | 800 | 114 | 1180 |
| 87 | 545 | 101 | 825 | 115 | 1215 |
| 88 | 560 | 102 | 850 | 116 | 1250 |
The full scale runs well beyond this in both directions, but most passenger cars sit between about 84 and 100, with larger SUVs, vans and heavily laden vehicles reaching higher.
How to use it when buying tyres
The rule is simple: a replacement tyre's load index must be equal to or higher than the figure the car maker specifies. That figure is printed on the placard inside the driver's door and in the handbook, alongside the recommended size and the speed rating.
Fitting a lower load index is a real safety problem. An under-rated tyre is working closer to its limit whenever the car is loaded, which builds heat and raises the risk of failure. It can also cause trouble with an insurer after an incident, and a tyre clearly unsuited to the vehicle can be picked up at the MOT. Fitting a higher load index is normally fine and simply adds capacity.
Load index and Extra Load tyres
Some vehicles need more capacity than a standard casing provides, and use Extra Load (XL) tyres. These carry a higher load index at a higher inflation pressure. It is important not to confuse the two: an Extra Load tyre only reaches its rated capacity when inflated to the higher pressure it is designed for, so the correct pressures matter as much as the index itself.
Where to find the right figure
The definitive source is the door placard, which lists the car maker's recommended size, pressures, load index and speed rating together. Matching the load index there, and inflating to the listed pressures, keeps the tyre operating with the margin the car was designed around. Enter the registration at Tyres.co.uk or another online tyre retailer and only tyres carrying at least the required load index come up.
From the workshop: people focus on the speed rating and forget the load index, but on a loaded estate or a van it is the one that actually matters day to day. Drop below the placard figure and the tyre is overloaded before the family and the luggage are even on board.
Sources and accuracy. The load index figures on this page follow the standard industry load index reference table used across the tyre trade, and are given as a general guide. The definitive load index for any specific car is the one on the placard inside the driver's door and moulded on the tyre's own sidewall. If anything here looks wrong, get in touch and we will check it and put it right.
Common questions
What is the load index on a tyre?+
The load index is a number that codes for the maximum weight a single tyre can carry at its correct pressure. It is read from a standard chart rather than being the weight itself, so a load index of 91 means 615kg per tyre.
What load index do I need?+
The minimum load index is set by the car maker and printed on the placard inside the driver's door. A replacement should match or exceed it, never fall below it, as the figure is matched to the car's fully laden weight.
Is a higher load index better?+
A higher load index is generally safe to fit and simply means more carrying capacity. The main thing to check is that a higher-rated tyre does not also force a much higher pressure that the car is not set up for, which can firm up the ride.
What does 91 mean on a tyre?+
91 is a load index. On the standard chart it equals 615kg, the maximum weight that one tyre can carry at full inflation. Across four tyres that covers the car's laden weight with a safety margin.