Tire load index chart

What the load index means

The load index is the number in the service description on the sidewall, just before the speed letter. In 225/45R17 94W, 94 is the load index and W is the speed rating. Each number stands for a maximum load per tire, from index 0 (45 kg, 99 lb) to 279 (136,000 kg). That load is the maximum at the tire's maximum rated inflation, so the number tells you what the tire can carry, not what pressure to run. Your vehicle's tire placard and owner's manual give the pressure and the load index for your vehicle.

Tire load index chart (60 to 150)

Maximum load per tire for each load index, in kg and lb. The tool above covers the full range from 0 to 279.

How to use the tools

• Load index or marking: type 94, paste 94W XL, or a light-truck pair such as 121/118S. You get the load per tire, for a set of four, and for an LT pair both the single and the dual figure.
• What load index do I need: enter a load per tire, or an axle load, which the tool divides by 2. It finds the lowest index in the chart that reaches it.

The formula

The chart is defined in kg. Pounds and the load of a set follow from it:

Worked example: load index 94 is 670 kg. 670 × 2.20462 = 1,477 lb per tire. Four tires carry up to 2,680 kg, which is 5,908 lb. The other way round: for 1,500 lb per tire, 94 falls short and 95 (690 kg, 1,521 lb) is the lowest index that reaches it.

Two numbers: 121/118

Light-truck tires that can run in dual pairs carry two load indexes. The first is for the tire mounted single, the second for each tire in a dual pair. In 121/118S, 121 means 1,450 kg (3,197 lb) per tire when single. 118 means 1,320 kg (2,910 lb) per tire when dual, so 2,640 kg (5,820 lb) for the pair.

SL, XL, extra load and reinforced

SL means standard load. XL means extra load; reinforced is another name for it. An XL tire has a higher load index than the SL version of the same size, and it reaches that higher load at a higher inflation pressure. The load index printed on the sidewall is the one to read: it already includes the XL rating.

Load range and ply rating

Light-truck (LT) tires carry a load range letter. Each letter matches a ply rating: B is 4, C is 6, D is 8, E is 10, F is 12 and G is 14, up to N at 24. A ply rating is a strength equivalent. A load range E tire is rated as strong as a 10-ply tire, not built from 10 plies. The load in lb and kg is still given by the load index on the sidewall.

What the chart does not tell you

The chart gives a tire's rated maximum. It does not say which tire your vehicle needs, and a higher number does not replace the placard. The vehicle's own ratings, the pressure on the placard and the owner's manual decide how the tire is used.

Questions

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