Truck Tire Speed Rating Chart
A truck tire speed rating chart decodes the letter on a sidewall and translates it into the maximum sustained speed a tire can handle when correctly inflated and loaded. For trucks, that letter is only part of the picture. Tire size, load index, and inflation pressure all influence how much heat the casing builds at highway speed, which is why owners should use the chart as a comparison tool rather than a driving target.
Essential answer
A truck tire speed rating chart is a reference that pairs sidewall letters with maximum speed values. Common symbols include L, M, N, P, Q, R, S, T, U, and H, but many truck applications occupy only part of that range because heavy casings prioritize load capacity. The letter does not indicate acceleration, cornering, or tread depth life. It identifies a thermal ceiling: the sustained speed the tire can tolerate when inflated correctly and loaded to its stated limit.
For a truck owner, the essential answer is that the chart supports comparison, not a driving target. A tire can exceed its speed rating even when the speedometer is below the printed number if the truck is heavily loaded, underinflated, or towing near its maximum. Heat accumulates from sidewall flex and tread distortion, and the rating marks the heat threshold the tire can manage. Replacement tires should meet or exceed the original equipment specification rather than relying on the lowest letter that appears acceptable for local driving.