Tire load index is the number after the size, for example 116 on a 275/65R20 116T. It is pounds per tire at the inflation on the sidewall, written as a code. The letter after it is the speed rating. Neither changes diameter or width. Both change whether the tire is legal on that vehicle. This calculator ignores them on purpose. This page does not.
Load index chart
Match or exceed the door-jamb requirement. Going below is how you overload a tire that "fit fine." Extra capacity is allowed. Extra unsprung weight is a ride and mpg cost, not a free upgrade.
| Index | Pounds per tire | Kilograms |
|---|---|---|
| 84 | 1,102 | 500 |
| 87 | 1,201 | 545 |
| 91 | 1,356 | 615 |
| 94 | 1,477 | 670 |
| 95 | 1,521 | 690 |
| 98 | 1,653 | 750 |
| 101 | 1,819 | 825 |
| 104 | 1,984 | 900 |
| 107 | 2,149 | 975 |
| 110 | 2,337 | 1,060 |
| 113 | 2,535 | 1,150 |
| 116 | 2,756 | 1,250 |
| 121 | 3,197 | 1,450 |
| 126 | 3,748 | 1,700 |
Speed rating
Speed rating is the maximum sustained speed the tire is built for. S is 112 mph, T is 118, H is 130, V is 149. The full letter list lives on the tire speed rating chart. On a truck that never sees 90, a T is not a performance upgrade. Do not go below the placard letter to save money on a "same size" tire.
Load range is a third thing
LT tires also carry a load range (C, D, E, F) that describes ply rating and inflation. An E-load 275/65R20 and a P-metric 275/65R20 share a diameter and do not share a capacity. The stamp has to be read as a whole. The how to read page puts them in order.