Guide
Load range vs load index
One is a construction class, the other is a weight. Tires carry both.
Short answer
Load range is a light truck tire’s strength class, a letter that sets its maximum pressure: E is the old 10-ply rating, built for 80 psi. Load index is the weight the tire carries at that pressure. An LT265/75R16 in load range E is usually marked 123/120, which is 3,417 lb per tire on a single axle.
Load ranges
| Load range | Ply rating | Maximum pressure |
|---|---|---|
| C | 6 | 50 psi |
| D | 8 | 65 psi |
| E | 10 | 80 psi |
| F | 12 | 95 psi |
"Ply rating" is a strength equivalent from the days of bias-ply tires, not a count of layers; a modern load range E tire may have far fewer actual plies. Passenger tires use a different system: SL (standard load) and XL (extra load), which allows a higher pressure and a higher load index in the same size.
Load index on load range E tires
| Size | Marking | Single | Dual |
|---|---|---|---|
| LT265/75R16 E | 123/120 | 3,417 lb | 3,086 lb |
| LT275/70R18 E | 125/122 | 3,638 lb | 3,307 lb |
| LT285/75R16 E | 126/123 | 3,748 lb | 3,417 lb |
The load range does not give the load; the size and the construction do. That is why the same letter E carries different weights on different sizes, and why you read the load index from the sidewall rather than from the load range.
What to match when you replace tires
The door jamb label gives the load index, or the load range, the vehicle was fitted with. Match or exceed it. Fitting a load range E tire where C was fitted is allowed and common on trucks that tow, but the ride gets firmer, and it only carries its rated load at its higher pressure: at the lower pressure the vehicle calls for, it carries about what the original did.