Load index,
in kilograms
The two digits before the speed symbol are a code, not a weight. This is the table they index into.
91 = 615 kg A load index of 91 means one tyre may carry 615 kg at its rated inflation pressure — 2,460 kg across a set of four.
The relationship is not linear and there is no formula: it is a published table, and the only correct way to use it is to look your own figure up and compare it against the placard in your door aperture.
The full table
| Index | Per tyre | Per set of four | Index | Per tyre | Per set of four |
|---|---|---|---|---|---|
| 60 | 250 kg | 1,000 kg | 96 | 710 kg | 2,840 kg |
| 61 | 257 kg | 1,028 kg | 97 | 730 kg | 2,920 kg |
| 62 | 265 kg | 1,060 kg | 98 | 750 kg | 3,000 kg |
| 63 | 272 kg | 1,088 kg | 99 | 775 kg | 3,100 kg |
| 64 | 280 kg | 1,120 kg | 100 | 800 kg | 3,200 kg |
| 65 | 290 kg | 1,160 kg | 101 | 825 kg | 3,300 kg |
| 66 | 300 kg | 1,200 kg | 102 | 850 kg | 3,400 kg |
| 67 | 307 kg | 1,228 kg | 103 | 875 kg | 3,500 kg |
| 68 | 315 kg | 1,260 kg | 104 | 900 kg | 3,600 kg |
| 69 | 325 kg | 1,300 kg | 105 | 925 kg | 3,700 kg |
| 70 | 335 kg | 1,340 kg | 106 | 950 kg | 3,800 kg |
| 71 | 345 kg | 1,380 kg | 107 | 975 kg | 3,900 kg |
| 72 | 355 kg | 1,420 kg | 108 | 1,000 kg | 4,000 kg |
| 73 | 365 kg | 1,460 kg | 109 | 1,030 kg | 4,120 kg |
| 74 | 375 kg | 1,500 kg | 110 | 1,060 kg | 4,240 kg |
| 75 | 387 kg | 1,548 kg | 111 | 1,090 kg | 4,360 kg |
| 76 | 400 kg | 1,600 kg | 112 | 1,120 kg | 4,480 kg |
| 77 | 412 kg | 1,648 kg | 113 | 1,150 kg | 4,600 kg |
| 78 | 425 kg | 1,700 kg | 114 | 1,180 kg | 4,720 kg |
| 79 | 437 kg | 1,748 kg | 115 | 1,215 kg | 4,860 kg |
| 80 | 450 kg | 1,800 kg | 116 | 1,250 kg | 5,000 kg |
| 81 | 462 kg | 1,848 kg | 117 | 1,285 kg | 5,140 kg |
| 82 | 475 kg | 1,900 kg | 118 | 1,320 kg | 5,280 kg |
| 83 | 487 kg | 1,948 kg | 119 | 1,360 kg | 5,440 kg |
| 84 | 500 kg | 2,000 kg | 120 | 1,400 kg | 5,600 kg |
| 85 | 515 kg | 2,060 kg | 121 | 1,450 kg | 5,800 kg |
| 86 | 530 kg | 2,120 kg | 122 | 1,500 kg | 6,000 kg |
| 87 | 545 kg | 2,180 kg | 123 | 1,550 kg | 6,200 kg |
| 88 | 560 kg | 2,240 kg | 124 | 1,600 kg | 6,400 kg |
| 89 | 580 kg | 2,320 kg | 125 | 1,650 kg | 6,600 kg |
| 90 | 600 kg | 2,400 kg | 126 | 1,700 kg | 6,800 kg |
| 91 | 615 kg | 2,460 kg | 127 | 1,750 kg | 7,000 kg |
| 92 | 630 kg | 2,520 kg | 128 | 1,800 kg | 7,200 kg |
| 93 | 650 kg | 2,600 kg | 129 | 1,850 kg | 7,400 kg |
| 94 | 670 kg | 2,680 kg | 130 | 1,900 kg | 7,600 kg |
| 95 | 690 kg | 2,760 kg |
SOURCE·ETRTO / T&RA published load-index table·standard values, not interpolated·REVIEWED ETRTO STANDARD
How to use it without getting it wrong
- Read the tyre placard in your driver's door aperture. It gives the original size with its load index and speed symbol.
- Whatever you fit must have a load index equal to or higher than that figure. Equal is fine. Higher is fine. Lower is not a compromise, it is a defect.
- If the car is often loaded — a van, a tow vehicle, a seven-seater with seven people in it — the placard may specify a reinforced or XL casing. That is expressed as a higher load index, so the index is still the number to check.
- The rating assumes the tyre is at its rated pressure. An under-inflated tyre does not carry its rated load, which is why the placard also gives pressures.
Load index — the questions that follow
What does load index 91 mean?
615 kg — the maximum load one tyre may carry at its rated pressure. The index is a code into a standard table, not a weight or a percentage. A full set of 91s carries 2,460 kg.
Can I fit a tyre with a higher load index?
Yes. Higher is always permitted and is sometimes required — vans and heavily-loaded SUVs often specify a reinforced or XL casing. What you must not do is go lower than the figure on your vehicle's tyre placard.
Where do I find the load index my car needs?
On the tyre placard, a plate or sticker in the driver's door aperture, sometimes inside the fuel flap or the glovebox. It lists the vehicle's original sizes with their load index and speed symbol, and it outranks every website including this one.
The other half of the code is on the speed-symbol table, and the size itself is decoded on the sidewall page. The geometry here is exact; whether a tyre fits YOUR car is not something geometry can answer. Arch clearance, suspension travel, offset, load rating and your vehicle's own placard all decide that, and none of them are in a size string. The ±3% rule quoted throughout is an industry convention, not a law. Confirm any change against the tyre placard on your door pillar and with a tyre fitter before you buy.