Tire Speed Rating Chart: How to Read Letters and Sidewall Codes

What the specification means

The speed rating, also called the speed symbol, is part of the service description that follows the tire size. Take 225/45R17 94V as an example. 225 is the section width in millimeters, 45 is the aspect ratio, R means radial construction, and 17 is the rim diameter in inches. 94 is the load index, which corresponds to 1,477 lb per tire, and V is the speed rating. The rating comes from laboratory testing on a drum at a set load and inflation. It is a certified limit, not a recommended cruising speed, and it never overrides posted limits or road conditions.

Common speed rating letters for passenger and light truck tires follow this scale: L 75 mph (120 km/h), M 81 mph (130 km/h), N 87 mph (140 km/h), P 93 mph (150 km/h), Q 99 mph (160 km/h), R 106 mph (170 km/h), S 112 mph (180 km/h), T 118 mph (190 km/h), U 124 mph (200 km/h), H 130 mph (210 km/h), V 149 mph (240 km/h), W 168 mph (270 km/h) and Y 186 mph (300 km/h). J (62 mph, 100 km/h) and K (68 mph, 110 km/h) appear on some special-service tires. H sits between U and V instead of in alphabetical order, a leftover from older labeling, so read each letter against the scale rather than assuming that a later letter means a higher speed.

Z ratings come from an older system. ZR inside the size, as in 245/35ZR19, means the tire is rated for speeds above 149 mph. Current Z-rated tires normally also carry a service description such as 93Y, which sets the actual limit. A Y in parentheses, written (Y), means capability above 186 mph, with the exact ceiling set by the tire maker. Some older tires place the letter inside the size, as in 205/60HR15. Modern practice puts it after the load index.

Comparing common letters: S, T, H, V, W and Y

S and T ratings, at 112 and 118 mph, are common on family sedans, minivans and many all-season tires. Comparing T and H is a question of 118 versus 130 mph. H versus V is 130 versus 149 mph, a frequent choice on sedans with sport trims. V, W and Y ratings appear on performance vehicles, where the step from W to Y raises the limit from 168 to 186 mph. Moving up one or more letters from the specification is generally acceptable. Moving below it is not, unless the vehicle maker allows it. A higher letter is a minimum requirement met with margin, not a quality score. Tread compound, ride comfort and wear vary by tire model regardless of the letter.

Light truck (LT) tires and many winter tires often carry lower speed ratings than comparable passenger tires. On LT tires, do not confuse the load range letter, such as C, D or E, with the speed symbol. The load range describes construction and pressure capability. The speed symbol still sits at the end of the service description, for example 121/118S, where the two numbers are the single and dual load indexes.

Identify the applicable version

A model name alone does not tell you the correct speed rating. The same model can use different original sizes and ratings depending on model year, trim, drivetrain, wheel diameter and optional performance packages. Identify your vehicle by model year, trim, front-wheel, rear-wheel or all-wheel drive configuration, and the wheel size actually fitted. A dealer can confirm the original fitment from the VIN. Vehicles with staggered fitments may specify different sizes, load indexes or speed ratings for the front and rear axles.

The tires currently on the vehicle are not proof of the specification. A previous owner or shop may have fitted different wheels or lower-rated tires, so always compare against the vehicle's own records.

Read the correct specification

The vehicle placard, usually on the driver's door jamb, lists the original tire size, the recommended cold inflation pressure for front and rear tires, and the maximum combined weight of occupants and cargo. Some placards also show the load index and speed symbol. If yours does not, the tire section of the owner's manual gives the specified service description. Do not use the maximum pressure molded into the sidewall as your inflation target. That figure is the tire's limit, not the vehicle maker's recommendation.

On the tire, the speed rating appears right after the size and load index on the sidewall. The DOT code nearby identifies the manufacturer, plant and production week and year, and it is separate from the rating. The full DOT serial may appear on only one side of the tire, so check both sidewalls if you need the build date.

Apply the limits correctly

A tire's rating assumes correct inflation pressure, a load within the load index, and sound condition. Underinflation, overloading, towing, high ambient heat, cuts, impact damage, low tread depth and age all reduce the real safety margin. For V, W and Y tires, published standards reduce the permitted load near the top of the speed range. Many tire makers do not honor the original speed rating after a puncture repair, so check the maker's policy before relying on a repaired tire at sustained high speed.

Replacement tires should equal or exceed the specified load index and speed rating. A higher speed rating does not make up for a lower load index. If you mix ratings, the vehicle is limited by its lowest-rated tire. Keep matching tires on each axle, and ideally fit all four alike. Some vehicle makers permit lower-rated winter tires as long as the driver stays within the lower limit, so check the owner's manual for that allowance. Drivetrain compatibility matters on all-wheel and four-wheel drive vehicles. They need matching size and tread design, and tread depth within the vehicle maker's tolerance, because uneven tire diameters can stress the driveline. Replacing a single tire on these vehicles may require replacing others or shaving the new one to match.

A short verification checklist

Before buying, fitting or loading, confirm the exact vehicle: model year, trim, drivetrain and wheel diameter. Read the placard for the original tire size and cold inflation pressures, and take the specified load index and speed symbol from the placard or owner's manual. Check that the new tire's size matches and its load index and speed rating are equal or higher. On trucks, verify LT or passenger construction and the load range. Make sure tires match across each axle, and across all four corners on all-wheel drive. Inspect the tread depth, age and repair history of any tires you are keeping, and note any manufacturer allowance for winter tires.

After installation, set pressures cold to the placard values. If you plan heavy loads or towing, check the owner's manual for any different pressure it specifies for those conditions.