Right after the size on a tire's sidewall, you will find two characters that most people ignore: a number such as 91 and a letter such as V. The number is the load index — a code for how much weight one tire can carry. It matters when you replace tires, tow, carry heavy loads or switch to a different size, because a tire with too low a load index can overheat and fail. This calculator turns a load index into kilograms and pounds, and works backwards to find the smallest index a given load needs.
How to use the tire load index calculator
- Choose the direction: convert a load index to a load, or find the minimum index for a load.
- For an index: enter the number from the sidewall (60–130) and how many tires you want the total for.
- For a load: enter the load each tire must carry in pounds or kilograms.
- Read the maximum load per tire, the total for the set, and the minimum index.
The letter after the load index is the speed symbol — see the tire speed rating calculator. For vehicle weights and trailers, see the towing capacity calculator and the payload calculator.
Load index formula and table
Load of a set = load per tire × number of tires
Pounds = kilograms × 2.2046
- Load index — a two- or three-digit number in the tire's service description
- Table — the standard values for indexes 60–130 (tire industry table, as published by tire makers and the Wikipedia “Tire code” article)
- Minimum index — the smallest index whose load is at least the load the tire must carry
Worked example: 225/45R17 91V
- Read the service description after the size: 91 V — load index 91, speed symbol V.
- Table lookup: index 91 = 615 kg = 1,356 lb per tire.
- Four tires: 4 × 615 = 2,460 kg (5,424 lb) — the upper limit for the whole car, shared evenly.
- Reverse: a tire that must carry 1,100 lb (499 kg) needs index 84 (500 kg) or higher.
Common load indexes
These rows come from the load index table in this site's data folder.
| Load index | Max load per tire | In pounds | Four tires together |
|---|---|---|---|
| 75 | 387 kg | 853 lb | 1,548 kg |
| 82 | 475 kg | 1,047 lb | 1,900 kg |
| 87 | 545 kg | 1,202 lb | 2,180 kg |
| 91 | 615 kg | 1,356 lb | 2,460 kg |
| 95 | 690 kg | 1,521 lb | 2,760 kg |
| 99 | 775 kg | 1,709 lb | 3,100 kg |
| 104 | 900 kg | 1,984 lb | 3,600 kg |
| 108 | 1,000 kg | 2,205 lb | 4,000 kg |
| 112 | 1,120 kg | 2,469 lb | 4,480 kg |
| 116 | 1,250 kg | 2,756 lb | 5,000 kg |
| 120 | 1,400 kg | 3,086 lb | 5,600 kg |
| 125 | 1,650 kg | 3,638 lb | 6,600 kg |
| 130 | 1,900 kg | 4,189 lb | 7,600 kg |
Choosing the right load index
The vehicle's door-jamb label or owner's manual shows the tire size and load index the manufacturer requires. The rule is simple: a replacement tire must have at least that load index. A higher index is fine — and common on SUVs and vans where an XL (extra load) version of the same size is offered — but a lower one is not, even if the size matches.
The load index applies at the tire's rated pressure, so it is only valid if the tires are inflated correctly. Under-inflation reduces the load a tire can handle and builds heat, which is why checking pressure matters for loaded vehicles. When you tow or carry a heavy load, check that the weight on the most loaded axle, divided by the number of tires on it, is below the index load with a margin.
When you change tire size — for example when plus-sizing — check that the new tire's load index equals or exceeds the original, not just the dimensions. Tire size alone does not tell you the capacity: two tires with the same size can have different load indexes. To compare sizes see the tire size comparison calculator.
Sources
The load index to kilogram values (indexes 60–130) are from the tire-industry load index table as published in the Wikipedia article “Tire code”, spot-checked against Hankook's tire guide (index 91 = 615 kg, 100 = 800 kg) and Wheel-Size (110 = 1,060 kg); the table is stored in data/tire-load-index.csv. Pounds are computed as kilograms × 2.2046226.
Frequently asked questions
What does the load index on a tire mean?
It is a number from the tire’s service description (for example 91 in 225/45R17 91V) that corresponds to the maximum load the tire can carry at its rated pressure. 91 equals 615 kg (1,356 lb).
Where is the load index on the tire?
On the sidewall right after the size, followed by the speed symbol: 225/45R17 91V has load index 91 and speed symbol V.
Can I use a tire with a higher load index?
Yes. A higher index means a higher capacity, and it is acceptable as long as the tire fits and the speed rating matches. A lower index than the vehicle manufacturer specifies is not acceptable.
How do I find the minimum load index I need?
Take the load on the most heavily loaded axle, divide by the number of tires on it, and use the smallest index whose load is at least that value; your vehicle’s door-jamb label shows the manufacturer’s requirement.
Is the load index a total or per tire?
Per tire. The load for a set is the index load times the number of tires, which only gives a usable figure if the weight is evenly shared.