Tires

A load index is an assigned numerical value that signifies a tire's maximum load carrying capacity. They're useful to help compare load carrying capacity of different-sized tires, and as you might expect, the higher the tire's load index number, the greater its load carrying capacity. Using the image below of a P195/60R15 87S tire, the load index is the 87 near the end. The 87 identifies the tire's ability to carry approximately 1,201 pounds.

tire's load index and tire's speed rating

Typically, the load indexes of the tires used on passenger cars 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

When looking at light truck (LT) or newer Special Trailer Service (ST) tires, there are two load indexes branded on the sidewall, separated by a forward slash. Using an LT235/75R15 104/101S Load Range C tire as an example, the load index is 104/101. 104 corresponds to 1,984 pounds, and 101 corresponds to 1,819 pounds. So what is the true load carrying capacity of the tire? The answer changes depending on the situation in which the tire is being used.

Since LT tires are commonly used on trucks with dual rear wheels, they are branded with two load indexes. The first number indicates the load carrying capacity if the tire is installed on a truck with a single-wheel rear axle, and the second number applies when the tire is used in a dual rear application.

Though it may seem counterintuitive that a tire is rated to carry less weight when working in tandem with another tire in the dual pair, the purpose is to build in additional reserve capacity should one of the two tires fail, leaving the sole remaining tire to carry the load normally handled by two tires.

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