Tire Speed Rating Decoder

This decoder works by matching the speed rating letter to its maximum sustained speed in km/h and mph. The letter is the last character of the service description, such as V in 94V.

1. Enter the letter, for example V.
2. Read the maximum speed: 240 km/h (149 mph).
3. Read the typical vehicle type for that rating.
4. Compare with the rating on the vehicle placard.

The formula is a table lookup: Max Speed (km/h) = Table[Letter], with Max Speed (mph) = Max Speed (km/h) ÷ 1.609344.

The order is alphabetical from L to U, then H sits between U and V. Worked example: rating W is 270 km/h, which equals 168 mph.

The conversion table lists 14 speed ratings from L (120 km/h, 75 mph) to (Y) (above 300 km/h, 186 mph). Each row includes a typical use.

The H rating is out of alphabetical order. It comes from an older system, where H stood for high speed, and keeps its place between U and V.

The Tire Speed Rating Decoder is a tool that explains the letter code for a tire's maximum safe sustained speed. Speed ratings come from lab tests where the tire runs at increasing speed under load.

The rating is valid only at correct pressure, correct load and good condition. Underinflation, overload and damage all lower the real safe speed.

This decoder has 4 uses: replacement checks, winter tire choices, insurance checks and performance planning.

• Check replacements: Match or beat the placard rating.
• Choose winter tires: Know the lower ratings typical of winter tires.
• Check insurance rules: Some insurers require the placard rating.
• Plan performance use: Pick ratings for track days.