On a tire sidewall, 97W is the tire’s service description: “97” is its load index, and “W” is its speed rating. Together, these markings indicate the tire’s standardized load capacity and speed category—not the vehicle’s recommended tire pressure or a promise that a car can safely travel at the rating’s maximum speed. Knowing what 97W means can help drivers compare tires and avoid choosing a replacement that does not meet the vehicle manufacturer’s requirements.
What the 97W Tire Marking Means
The number and letter serve different purposes. A load index of 97 corresponds to a maximum load of 730 kilograms, or about 1,609 pounds, per tire under specified conditions. The W speed rating corresponds to speeds up to 168 mph, or 270 km/h, under standardized test conditions.
These figures describe the tire’s rating, not a recommended way to load or drive a vehicle. The vehicle’s owner’s manual and tire information placard specify the appropriate tire size, load capacity, and inflation pressure. Drivers should follow those instructions even when a tire’s sidewall shows a higher rating.
| Marking | Meaning | What It Does Not Mean |
|---|---|---|
| 97 | Load index; 730 kg (about 1,609 lb) maximum load per tire under specified conditions | The vehicle’s total payload or permission to exceed its weight limits |
| W | Speed rating; up to 168 mph (270 km/h) under standardized test conditions | A safe or legal driving speed recommendation |
What Is a Tire Load Index?
A tire load index is a number that corresponds to a specific maximum load capacity in a standardized chart. It is not a direct measurement of pounds, and the figures do not increase in a simple one-pound-per-number pattern. For a 97 load index, the listed capacity is 730 kilograms per tire.
That capacity applies under prescribed testing and inflation conditions. It does not mean a vehicle can safely carry 1,609 pounds multiplied by the number of tires. Vehicle limits also depend on the vehicle’s design, axle ratings, suspension, brakes, tire pressure, and how weight is distributed. The tire rating cannot raise the vehicle’s gross vehicle weight rating or its gross axle weight ratings.
Load capacity also depends on proper inflation. A tire that is underinflated may not support its rated load as intended and can build up excess heat. Drivers should use the cold inflation pressure shown on the vehicle’s placard, commonly located on the driver-side doorjamb, or specified in the owner’s manual. The maximum pressure molded into a tire’s sidewall is not usually the vehicle’s recommended pressure.
What Is a Tire Speed Rating?
The speed rating is represented by a letter and indicates the tire’s ability to perform at a specified speed under controlled test conditions. In the standard speed-rating chart, W corresponds to 168 mph. The rating is based on testing that considers factors such as heat buildup and tire performance at speed.
A W rating is not a suggested highway speed, a guarantee that the tire will withstand every condition at 168 mph, or authorization to exceed posted limits. Real-world performance can be affected by load, inflation, tire condition, road surface, weather, and vehicle setup. Tires may also be damaged by impacts, punctures, age, or improper repairs, regardless of their speed rating.
Speed ratings matter when matching replacement tires to a vehicle. Automakers select tire specifications for a particular vehicle’s intended use and handling characteristics. A replacement tire should meet the vehicle manufacturer’s requirements; a higher speed rating does not automatically make a tire a better choice, and a lower rating may not be suitable.
Where to Find 97W on a Tire
The 97W marking usually appears at the end of the tire’s size and service-description sequence. A sidewall might read 225/50R17 97W. The numbers and letter have separate meanings:
- 225: The tire’s nominal section width in millimeters.
- 50: The aspect ratio; the sidewall height is 50% of the nominal width.
- R: Radial construction.
- 17: The wheel diameter, in inches, that the tire is designed to fit.
- 97W: The service description, combining the load index and speed rating.
Other markings may appear nearby, including an “XL” or “Extra Load” designation, a manufacturer name, a DOT identification code, and information about maximum pressure. Those markings are not interchangeable with the service description. For example, “XL” indicates a reinforced tire category; it does not replace the need to check the load index and required pressure.
How 97W Compares With Other Tire Ratings
Load-index numbers correspond to different capacities, while speed-rating letters correspond to different speed categories. A tire marked 96W has a lower load index than one marked 97W, even though both have a W speed rating. A 97V tire has the same load index as a 97W tire but a lower speed category: V is rated for up to 149 mph, while W is rated for up to 168 mph.
| Example Marking | Load Index | Approximate Maximum Load Per Tire | Speed Rating |
|---|---|---|---|
| 96W | 96 | 710 kg (about 1,565 lb) | W: up to 168 mph |
| 97V | 97 | 730 kg (about 1,609 lb) | V: up to 149 mph |
| 97W | 97 | 730 kg (about 1,609 lb) | W: up to 168 mph |
| 98W | 98 | 750 kg (about 1,653 lb) | W: up to 168 mph |
Figures in tire load-index charts are expressed in kilograms and may be rounded when converted to pounds. The table is a comparison aid, not a substitute for vehicle specifications. Tire models with the same size and service description can still differ in construction and performance.
Can a 97W Tire Replace Another Rating?
Whether a 97W tire is an appropriate replacement depends on the vehicle’s specified tire size and service requirements. The replacement must fit the wheel and vehicle, provide adequate load capacity, and meet the manufacturer’s requirements for speed rating and other characteristics. The original-equipment tire may have additional specifications that are not captured by “97W” alone.
If a vehicle’s placard specifies a lower speed rating, a W-rated tire may be acceptable if it also meets the required size and load specifications, but drivers should confirm fitment with the vehicle maker or a qualified tire professional. If the placard calls for a higher rating, substituting a lower-rated tire may not meet the vehicle’s requirements. Regional rules and vehicle warranties can also affect replacement choices.
Drivers should not assume that a higher load index allows more cargo. The vehicle’s payload and axle limits still apply, and all tires should be inflated to the vehicle maker’s recommended cold pressure. For mixed setups, such as vehicles with different front and rear tire sizes, each axle must use the specified tire type and rating.
How to Check the Correct Tire for a Vehicle
- Read the vehicle placard. Check the driver-side doorjamb for the original tire size and recommended cold pressure.
- Consult the owner’s manual. It may list approved tire sizes, load and speed requirements, and guidance for alternate equipment.
- Compare the full sidewall size. Confirm width, aspect ratio, construction, and wheel diameter, not just the 97W marking.
- Check the service description. Make sure the load index and speed rating meet the vehicle manufacturer’s specifications.
- Ask a qualified tire professional when uncertain. This is especially helpful for modified vehicles, staggered tire setups, or tires with XL and other special designations.
When replacing tires, it is generally important to use matching tires on the same axle and to follow the vehicle manufacturer’s recommendations about replacing tires in pairs or sets. Differences in size, tread, or performance can affect handling and vehicle systems. A professional can help verify compatibility before installation.
Common Misunderstandings About 97W
- “97” does not mean 97 pounds. It is a chart-based load index corresponding to 730 kilograms per tire.
- “W” is not a recommended driving speed. It is a standardized speed category, not a safe-speed instruction.
- The load rating does not set tire pressure. Use the pressure on the vehicle placard or in the owner’s manual.
- A stronger-looking rating does not override vehicle limits. The tire does not change the vehicle’s payload, axle, or gross weight ratings.
- Matching 97W alone does not guarantee fitment. Tire size, construction, clearance, and vehicle-specific requirements also matter.
Sources and Further Guidance
For vehicle-specific tire and pressure information, consult the tire placard and owner’s manual. The National Highway Traffic Safety Administration’s tire safety guidance explains tire selection, inflation, and maintenance. The U.S. Tire Manufacturers Association provides consumer information about tire care and industry standards. Load-index and speed-rating details should be checked against current tire-industry charts and the tire manufacturer’s specifications.