Meta description: Learn what 125/122R means on a tire, including its single- and dual-wheel load ratings, R speed rating, and how to use the information safely.
The marking 125/122R on a tire identifies its load-carrying capacity and speed rating. It is commonly found on commercial, light-truck, and van tires. The two numbers refer to different load limits depending on whether the tire is mounted alone or paired with another tire on the same side of an axle. The letter indicates the tire’s rated speed category. Knowing how to read this code helps drivers compare replacement tires, but it does not replace the vehicle manufacturer’s guidance on tire size, inflation pressure, or load limits.
What 125/122R Means at a Glance
The code has three parts: 125, 122, and R. The first two are load index numbers, while the final letter is a speed rating.
| Marking | Meaning | Approximate rating per tire |
|---|---|---|
| 125 | Load index for single-tire fitment | 1,650 kg, or about 3,638 lb |
| 122 | Load index for dual-tire fitment | 1,500 kg, or about 3,307 lb |
| R | Speed rating | Up to 170 km/h, or about 106 mph, under specified conditions |
These are standardized rating values, not a promise that a tire can safely carry that load at any pressure, speed, temperature, or road condition. The actual operating limits depend on the tire’s specifications and the vehicle manufacturer’s instructions.
What the 125 Load Index Means
The first number, 125, is the load index for a tire used in a single-wheel position. A load index is a code that corresponds to a specific maximum load capacity in an industry reference table. For index 125, that capacity is 1,650 kilograms, approximately 3,638 pounds, per tire.
“Single” means one tire is mounted at each end of the axle. For example, a vehicle with two rear wheels, one on each side, uses a single-tire configuration on that axle. The rating is for each tire, not for the entire axle. Although two tires with a 125 rating add up to about 7,276 pounds on paper, the vehicle’s axle rating, wheel capacity, suspension, and other components may impose a lower limit.
What the 122 Load Index Means
The second number, 122, applies when tires are installed in a dual configuration: two tires mounted side by side at each end of the axle. A load index of 122 corresponds to 1,500 kilograms, or about 3,307 pounds, per tire.
Dual-rated capacity is lower per tire than single-rated capacity because closely spaced tires can experience different operating conditions, including heat buildup and unequal loading. A dual-tire position also needs enough clearance between the tires to prevent rubbing as they flex under load. The 122 figure is therefore not a spare value to substitute for 125; each applies to a particular mounting arrangement.
With four tires in a dual-tire axle position, multiplying 3,307 pounds by four gives a theoretical tire-capacity total of about 13,228 pounds. That number does not establish the axle’s legal or safe carrying capacity. The vehicle’s gross axle weight rating (GAWR), gross vehicle weight rating (GVWR), wheel ratings, and tire pressures remain controlling limits.
What the R Speed Rating Means
The final letter, R, is the tire’s speed symbol. In the standard speed-rating scale, R corresponds to a maximum speed of 170 kilometers per hour, or approximately 106 miles per hour, when the tire is correctly maintained and operated under specified test conditions.
This rating is not a recommended driving speed or a guarantee of safe performance at 106 mph. A vehicle may have a lower speed limit based on its tires, loading, handling, or manufacturer guidance. Heavy loads, low inflation pressure, damage, high temperatures, and long periods of fast driving can also affect tire performance. Drivers should obey posted limits and follow the vehicle and tire manufacturers’ operating instructions.
The letter R can appear in different places on a tire marking. In a code such as LT245/75R16, the R between the aspect ratio and wheel diameter means the tire has radial construction. In 125/122R, which appears after the load index pair, R is the speed symbol. Its meaning depends on where it appears in the full tire description.
Where to Find the Full Tire Rating
The 125/122R code is usually part of a longer marking on the tire sidewall. A commercial tire might show a size and service description such as LT245/75R16 125/122R. The size indicates dimensions and wheel fitment; the load index and speed symbol indicate service ratings. The sidewall may also show a maximum load and inflation pressure, plus construction, brand, and other information.
Drivers should compare the full tire size and service description with the vehicle’s certification label and owner’s manual. The vehicle label is commonly placed on the driver-side doorjamb, although its location can vary. It lists the original tire size and recommended cold inflation pressures. A tire that physically fits the wheel is not necessarily an appropriate replacement if its load rating, size, or other specifications are unsuitable.
Why Inflation Pressure Matters
Load index figures are associated with the tire’s capacity under specified conditions. In everyday use, a tire must be inflated to the pressure appropriate for the vehicle’s load and setup. Underinflation can reduce load-carrying capacity and cause excess heat, increasing the risk of tire damage or failure. Overinflation can affect ride and handling and may contribute to uneven wear.
For a passenger vehicle or light truck, the correct cold pressure is generally listed on the vehicle’s tire-and-loading information label or in the owner’s manual. The pressure printed on a tire sidewall is typically the maximum pressure associated with the tire’s maximum load, not the everyday pressure recommendation for every vehicle.
Commercial vehicles, recreational vehicles, and modified vehicles may require more specific load-and-pressure guidance. Their operators should consult the vehicle maker, tire maker, or a qualified tire professional. Tire pressure should be checked when the tires are cold, using a reliable gauge; a tire pressure monitoring system is useful but does not replace regular checks.
How to Use 125/122R When Choosing Replacement Tires
When replacing tires, the 125/122R marking can help confirm whether a tire’s service rating is appropriate, but it should not be the only comparison. A safe replacement should match the vehicle’s required size and meet or exceed the original equipment’s load capacity and speed rating, unless the vehicle manufacturer specifies otherwise.
- Check the vehicle label and manual. Confirm the correct size, tire type, and recommended pressure.
- Match the mounting setup. Use the single rating for a single position and the dual rating for a dual position.
- Check all tire ratings. Compare load index, speed symbol, construction, and any required commercial or winter specifications.
- Account for the whole vehicle. Do not exceed GVWR, GAWR, wheel ratings, or the tire maker’s limits.
- Use appropriate tires across an axle. Follow the vehicle and tire manufacturers’ guidance when replacing one tire or mixing tire types.
For vehicles with dual rear wheels, correct tire matching and spacing matter. Tires with different diameters, pressures, or tread conditions can share the load unevenly. A tire professional can help verify compatibility and confirm the proper inflation pressure for the vehicle’s actual load.
Common Misunderstandings About 125/122R
It Does Not Mean 125,122 Pounds
Load index numbers are codes, not direct weights. Index 125 corresponds to 1,650 kilograms per tire in a single fitment, while 122 corresponds to 1,500 kilograms per tire in a dual fitment. The values must be looked up in a load index chart.
The Ratings Are Not Axle Ratings
Each load figure applies to an individual tire. The vehicle’s axle and total weight limits are separate ratings. A vehicle cannot safely carry more than its rated limits just because the tires’ combined load indexes appear to allow it.
R Does Not Mean Radial in This Position
R means radial construction when it appears within a size code, such as LT245/75R16. At the end of the service description 125/122R, it is the speed symbol. Reading the full sidewall sequence prevents confusion.
The Sidewall Maximum Is Not the Vehicle’s Recommended Pressure
The maximum pressure molded on a tire is not automatically the correct operating pressure for a particular vehicle. The vehicle placard and manufacturer’s instructions are the starting point for inflation guidance.
When to Ask a Tire Professional
Professional advice is especially useful when a vehicle has dual rear wheels, carries heavy or uneven loads, uses a different tire size from the original, or has been modified. A tire specialist can check load capacity, wheel compatibility, clearance, pressure recommendations, and whether all tires are suitable for the same axle. For recreational and commercial vehicles, the manufacturer’s load and inflation information may also be essential.
Drivers should seek an inspection if a tire shows bulges, exposed cords, deep cuts, persistent pressure loss, or unusual vibration. Load and speed ratings do not make a damaged or improperly maintained tire safe. Regular inspection, correct cold inflation pressure, and respect for the vehicle’s weight limits are key parts of using a 125/122R tire responsibly.
Reliable Sources for Tire Ratings
For vehicle-specific information, the owner’s manual and the tire-and-loading label provide the most relevant starting points. The U.S. National Highway Traffic Safety Administration (NHTSA) offers consumer guidance on tire safety, pressure, and maintenance. Tire manufacturers publish size and load tables for their products, while industry standards organizations such as the Tire and Rim Association maintain technical tire and rim references. When guidance differs, the vehicle and tire manufacturers should be consulted for the exact application.