A tire load index is a crucial element that refers to a tire's highest load-bearing ability. Recognizing this numerical value can assist in comparing the load-bearing abilities of tires of different sizes. As a straightforward rule, a higher load index signifies a greater capacity to carry loads. Let's take, for instance, the P195/60R15 87S tire. Here, the load index is 87, signifying that this tire can carry around 1,201 pounds (545 kilograms).
Usually, the load indexes of the tires used on passenger cars, SUVs and light trucks range from 70 to 126.
| Load Index | Pounds | Kilograms | Load Index | Pounds | Kilograms | Load Index | Pounds | Kilograms | ||
|---|---|---|---|---|---|---|---|---|---|---|
| 70 | 739 | 335 | 89 | 1,279 | 580 | 108 | 2,205 | 1,000 | ||
| 71 | 761 | 345 | 90 | 1,323 | 600 | 109 | 2,271 | 1,030 | ||
| 72 | 783 | 355 | 91 | 1,356 | 615 | 110 | 2,337 | 1,060 | ||
| 73 | 805 | 365 | 92 | 1,389 | 630 | 111 | 2,403 | 1,090 | ||
| 74 | 827 | 375 | 93 | 1,433 | 650 | 112 | 2,469 | 1,120 | ||
| 75 | 853 | 387 | 94 | 1,477 | 670 | 113 | 2,535 | 1,150 | ||
| 76 | 882 | 400 | 95 | 1,521 | 690 | 114 | 2,601 | 1,180 | ||
| 77 | 908 | 412 | 96 | 1,565 | 710 | 115 | 2,679 | 1,215 | ||
| 78 | 937 | 425 | 97 | 1,609 | 730 | 116 | 2,756 | 1,250 | ||
| 79 | 963 | 437 | 98 | 1,653 | 750 | 117 | 2,833 | 1,285 | ||
| 80 | 992 | 450 | 99 | 1,709 | 775 | 118 | 2,910 | 1,320 | ||
| 81 | 1,019 | 462 | 100 | 1,764 | 800 | 119 | 2,998 | 1,360 | ||
| 82 | 1,047 | 475 | 101 | 1,819 | 825 | 120 | 3,086 | 1,400 | ||
| 83 | 1,074 | 487 | 102 | 1,874 | 850 | 121 | 3,197 | 1,450 | ||
| 84 | 1,102 | 500 | 103 | 1,929 | 875 | 122 | 3,307 | 1,500 | ||
| 85 | 1,135 | 515 | 104 | 1,984 | 900 | 123 | 3,417 | 1,550 | ||
| 86 | 1,168 | 530 | 105 | 2,039 | 925 | 124 | 3,527 | 1,600 | ||
| 87 | 1,201 | 545 | 106 | 2,094 | 950 | 125 | 3,638 | 1,650 | ||
| 88 | 1,235 | 560 | 107 | 2,149 | 975 | 126 | 3,748 | 1,700 |
In the context of light truck (LT) tires or the newer Special Trailer Service (ST) tires, it's common to see two load indexes marked on the tire's sidewall, divided by a slash. Let's use the LT235/75R15 104/101S Load Range C tire as an example. Here, the load index is 104/101. The first number (104) corresponds to 1,984 pounds, and the second number (101) corresponds to 1,819 pounds. But, how can we determine the accurate load carrying capacity of such a tire? The answer differs based on the specific application of the tire.
Since LT tires are often used on trucks featuring dual rear wheels, they are marked with two load indexes. The initial number denotes the load carrying capacity when the tire is mounted on a truck with a single-wheel rear axle. The second number comes into play when the tire is part of a dual rear wheel setup.
Although it may seem paradoxical that a tire is given a lower weight-bearing rating when paired with another tire, this is done to provide additional backup capacity in case one of the two tires fails. This ensures that the remaining tire can effectively handle the load that was previously carried by two tires.