Tire Speed Rating Chart: What Each Letter Means

What a tire speed rating means

A speed rating, also called a speed symbol or speed index, is a single letter printed on the sidewall right after the load index. In a marking such as 94H, the number 94 is the load index and H is the speed symbol. Together they form the service description. The letter defines the highest speed at which the tire can carry the load matching its load index, as established by standardized laboratory testing on a test drum at a set load and inflation pressure.

The rating describes a capability limit, not a recommended cruising speed, and it never overrides posted legal limits. It assumes correct inflation, no overloading and no damage. It is also separate from the UTQG grades molded on many passenger tires: the UTQG temperature grade reflects heat resistance in its own test, and it does not replace or translate into a speed symbol.

Speed rating letters chart in mph and km/h

The standard speed symbols and their maximum speeds are: L is 75 mph (120 km/h), M is 81 mph (130 km/h), N is 87 mph (140 km/h), P is 93 mph (150 km/h), Q is 99 mph (160 km/h), R is 106 mph (170 km/h), S is 112 mph (180 km/h), T is 118 mph (190 km/h), U is 124 mph (200 km/h), H is 130 mph (210 km/h), V is 149 mph (240 km/h), W is 168 mph (270 km/h) and Y is 186 mph (300 km/h). The scale was defined in km/h, so the mph figures are rounded conversions. Note that H sits between U and V rather than in alphabetical order, a holdover from older rating systems.

Lower codes also exist, such as J at 62 mph (100 km/h) and K at 68 mph (110 km/h), mostly on special-purpose, off-road or small tires. Q often appears on studless winter tires, S and T are widespread on passenger car and SUV all-season tires, H and V are common on sportier models, and W and Y belong to performance fitments. The gaps between neighboring letters vary: S versus T is 6 mph, H versus T is 12 mph, and H versus V is 19 mph.

Z, ZR and bracketed ratings

Z was originally introduced for tires capable of more than 149 mph (240 km/h). On current tires, ZR appears inside the size designation, as in 245/40ZR18, and signals capability above that threshold. The service description that follows, for example 97W or 97Y, defines the certified maximum. When the speed symbol is shown in parentheses, such as (Y), the tire is rated above 186 mph and the tire manufacturer must be consulted for its actual limit. Older tires marked only VR or ZR in the size, without a service description, also require the manufacturer's data to establish their limit.

Identify the applicable version

The speed rating your vehicle needs depends on the exact version, not the model name. One nameplate can be offered with different engines, wheel diameters, performance packages, speed limiters and drivetrains, and each combination may specify a different tire size and service description. Requirements can also change between model years. Confirm the model year, trim, drivetrain, original wheel size and whether the vehicle uses a staggered setup with different front and rear sizes. A dealer can look up the factory specification by VIN if the trim is unclear.

If the wheels have been changed from the factory fitment, the tire size printed for the original wheel no longer describes what is mounted. Any alternative size must still meet or exceed the original load capacity and speed rating and fit the vehicle's clearances, so confirm it with the vehicle or tire manufacturer rather than assuming it carries over.

Read the correct specification

Start with the vehicle placard, the tire and loading information label usually found on the driver's door jamb and sometimes on the fuel filler door or inside the glovebox. It lists the original tire sizes and cold inflation pressures, and on many vehicles it also shows the full service description. The tire section of the owner's manual covers approved sizes and may state minimum ratings, plus guidance for winter tires or a temporary spare.

To find the speed rating on a tire, read the sidewall size marking. In 225/60R17 99H, 225 is the section width in millimeters, 60 is the aspect ratio, R means radial construction, 17 is the rim diameter in inches, 99 is the load index and H is the speed symbol. Light truck tires may show two load indexes, as in 121/118S, for single and dual mounting, with the speed letter still last. Do not confuse the service description with the DOT code or the UTQG grades printed elsewhere on the sidewall.

Apply the limits correctly

Choose replacements with a speed rating equal to or higher than the original specification and a load index at least as high. A higher speed rating does not raise load capacity or change the placard inflation pressures. Keep the same rating on all four positions where possible. If ratings are mixed, the lowest-rated tire sets the limit for the whole vehicle, and matched pairs should share an axle. Some vehicle makers permit lower-rated winter tires provided the vehicle stays within that lower limit; follow the owner's manual. Temporary spares carry their own speed restriction, shown on the tire or its label.

Several conditions reduce the usable value of any rating: underinflation, overloading, prolonged heat, impact damage, age and improper repair. Many tire manufacturers treat a repaired tire as no longer carrying its original speed rating, so check the maker's repair policy. For some high-speed ratings, allowable load decreases at sustained speeds near the top of the range, and the tire manufacturer's load and speed data governs.

Drivetrain compatibility is a separate requirement. All-wheel-drive and many four-wheel-drive systems need matched size, type and tread depth on every tire, within the limits set by the vehicle manufacturer. A correct speed rating does not compensate for mismatched rolling diameters.

Motorcycle and scooter tires

Motorcycle tires use the same letter codes and speeds, with the service description on the sidewall, for example 120/70ZR17 (58W), where the parentheses follow the bracketed-rating rule described above. Bikes often specify different ratings and load indexes for the front and rear, and load capacity matters greatly once a passenger and luggage are added. Scooter tires commonly carry lower speed letters. In every case, the motorcycle or scooter manufacturer's specification takes precedence over a generic chart.

A short verification checklist

Before buying, servicing or loading, confirm the exact model year, trim, drivetrain and wheel size, then read the vehicle placard and owner's manual for the approved tire size, service description and cold inflation pressures. Check that each new tire's speed rating and load index meet or exceed that specification, and that front and rear sizes match a staggered setup if the vehicle uses one.

Next, verify that all four tires share the same rating, or that any mix follows the manufacturer's guidance and the lowest rating is respected. Confirm tread depth and size matching for all-wheel-drive systems, set pressures cold to the placard values, and stay within the vehicle's maximum load. Finally, inspect for damage, prior repairs and age, any of which can void the original rating.