Load Index & Speed Rating

Tire Load Index and Speed Rating Explained

The load index is a number on the tire sidewall that corresponds to a maximum weight capacity per tire. It is NOT the weight itself — you must look it up in a table.

The speed rating is a letter that indicates the maximum sustained speed the tire is designed for. Always match or exceed your vehicle manufacturer's recommended load index and speed rating.

Load index table (common range): LI 71 = 761 lbs, 75 = 853 lbs, 80 = 992 lbs, 85 = 1,135 lbs, 90 = 1,323 lbs, 95 = 1,521 lbs, 100 = 1,764 lbs, 105 = 2,039 lbs, 110 = 2,337 lbs. Most passenger cars use load index 71–100; light trucks and SUVs often use 100–115. The maximum load per tire must exceed 1/4 of GVWR (Gross Vehicle Weight Rating) with full load.

Speed rating letters: Q = 99 mph, S = 112 mph, T = 118 mph, H = 130 mph, V = 149 mph, W = 168 mph, Y = 186 mph, (Y) = above 186 mph. Passenger cars for normal use are typically rated H or V. Performance tires are W or Y. Never install a tire with a lower speed rating than the vehicle manufacturer specifies — it reduces the safety margin at highway speeds.

Real-world significance: load index is not a practical daily driving limit but a structural safety margin. Tires normally operate at 50–80% of their rated load capacity. Exceeding 100% causes rapid heat buildup, structural fatigue, and blowout risk. When towing or carrying heavy loads, verify that combined tire load ratings (LI × 4 tires) exceed your total loaded vehicle weight.

Run-flat tires carry a separate designation and have different load capacity at zero pressure than the normal load index implies. Standard tires should not be confused with run-flat specifications — the load index on a run-flat refers to normal operation, not zero-pressure mode.

See also: Tire Size Calculator · Wheel Offset Calculator