Load Index 123 is the maximum weight one tire can safely carry

A load index is a number assigned to a tire that tells you the heaviest load that single tire can support at its maximum air pressure. Load index 123 means that tire can carry 1,874 pounds when inflated to the pressure listed on the tire's sidewall. This number appears on every tire's sidewall right after the tire size — for example, a tire marked 225/50R17 98H includes the load index 98.

Load index numbers run from 0 to 150, and each number represents a specific weight in pounds. The higher the number, the heavier the load the tire can handle. A load index of 123 is relatively high and is commonly found on performance tires, truck tires, and tires for heavier vehicles. You will not see load index 123 on economy sedan tires, which typically range from 82 to 95.

The load index is paired with a speed rating — the letter that follows the number on the sidewall. Together they tell you both how much weight the tire can carry and how fast you can safely drive it. A tire marked 123H can carry 1,874 pounds at speeds up to 130 mph; a tire marked 123V can carry the same weight at speeds up to 149 mph.

Key Takeaways

  • Load index 123 means one tire can safely carry 1,874 pounds when inflated to the pressure printed on the tire sidewall.
  • You must match or exceed your vehicle's load index requirement — using a lower load index tire than your vehicle needs creates a safety risk and may void your warranty.
  • The load index appears on the tire sidewall when ready before the speed rating letter, and you can find your vehicle's required load index in the owner's manual or on the driver's door jamb placard.
  • Load index is different from tread wear rating and does not tell you how long the tire will last or how well it grips wet roads.

How load index connects to your vehicle's weight

Your vehicle has a Gross Vehicle Weight Rating (GVWR), which is the maximum total weight the vehicle can safely carry — including the vehicle itself, passengers, cargo, and fuel. To find your GVWR, look at the placard on the driver's door jamb or in your owner's manual. That number tells you the total load your four tires must be able to support together.

To find the load index you need, divide your GVWR by four. If your GVWR is 7,500 pounds, each tire must have a load index that supports at least 1,875 pounds. Load index 123 (1,874 pounds) would be just barely sufficient, while load index 124 (1,889 pounds) would give you a small safety margin. Most manufacturers recommend choosing a tire with a load index slightly higher than the minimum to account for uneven weight distribution and wear over time.

Never install a tire with a load index lower than what your vehicle requires. Underrated tires can overheat, fail suddenly, and increase stopping distance. Insurance companies and vehicle manufacturers may deny claims related to tire failure if you used tires below the required load index.

Load index 123 on different vehicle types

Load index 123 appears most often on pickup trucks, SUVs, and performance cars. A full-size truck might require load index 120 to 125 across all four tires. A performance sedan might use load index 123 tires to handle the weight of a turbocharged engine and reinforced suspension. A luxury SUV might pair load index 123 with a high speed rating like V or W to support both weight and highway performance.

Passenger sedans and compact cars rarely use load index 123 — they typically need load indices between 82 and 100. If you own a vehicle that calls for load index 123, you are driving something heavier or more powerful than average, and using the correct load index is especially important because the tire is already working near its limit under normal driving conditions.

When shopping for replacement tires, always match or exceed the load index printed on your vehicle's door jamb placard. Some tire retailers will try to sell you a cheaper tire with a lower load index; this is a cost-cutting move that puts you at risk. The small savings on the tire price is not worth the safety hazard or the potential liability if something goes wrong.

Load index versus other tire ratings

Load index is often confused with other numbers on the tire sidewall, but they measure different things. The tread wear rating — a three-digit number like 500 or 800 — tells you how long the tire is expected to last relative to a standard test tire. A higher tread wear rating means longer tire life. Load index tells you weight capacity, not durability.

The temperature rating (A, B, or C) indicates how well the tire resists heat buildup during driving. A tire with load index 123 and temperature rating A can carry 1,874 pounds and handle high-speed driving without overheating. These ratings are independent — a tire can have a high load index but a low temperature rating, or vice versa.

The traction rating (AA, A, B, or C) measures how well the tire grips wet pavement. This also has nothing to do with load index. A tire with load index 123 and traction rating AA can carry heavy loads and grip wet roads well, but you need to check both numbers to know what you are getting.

Reading the load index on your tire sidewall

The load index appears in the tire size designation, which is printed on the sidewall in large letters. A typical size might read 275/55R20 123S. Breaking this down: 275 is the width in millimeters, 55 is the aspect ratio (sidewall height as a percentage of width), R means radial construction, 20 is the wheel diameter in inches, 123 is the load index, and S is the speed rating.

The load index always comes when ready before the speed rating letter. If you see 123S, 123H, or 123V, the 123 is the load index. Some tires also include a load range letter (like C, D, or E on truck tires) that provides additional load information, but the numeric load index is the primary specification.

If you cannot find the load index on your tire, check your vehicle's door jamb placard or owner's manual. The placard lists the tire size and load index your vehicle requires. You can also use an online tire database by entering your vehicle's year, make, and model — most tire retailers' websites have this tool and will show you the correct load index for your vehicle.

What happens if you use the wrong load index

Using a tire with a load index lower than required creates several risks. The tire works harder to support the same weight, generating more heat. Over time, this heat breaks down the rubber and can cause a blowout, especially on long highway drives or in hot weather. Underrated tires also have a shorter lifespan and may fail suddenly without warning.

Using a tire with a higher load index than required is safe and is actually common practice. A tire rated for 1,900 pounds can safely carry 1,875 pounds. The extra capacity provides a safety margin and does not affect ride quality or fuel economy. Most tire shops will recommend matching the exact load index, but going one or two numbers higher is acceptable and sometimes preferable.

If you are unsure whether a tire meets your vehicle's requirements, ask the tire shop to verify before installation. They can cross-reference your vehicle's GVWR against the tire's load index in seconds. This takes 30 seconds and prevents a costly or dangerous mistake.

Frequently Asked Questions

Can I use a tire with load index 122 if my vehicle requires 123?

No. Load index 122 supports 1,859 pounds, which is 15 pounds less than load index 123. While the difference seems small, it means your tires are underrated for your vehicle's weight. Over time, this creates excess heat and wear. Always match or exceed your vehicle's required load index.

Does load index affect how comfortable the ride feels?

Load index itself does not affect ride comfort. The sidewall stiffness and construction of the tire affect comfort more than the load index number. Two tires with the same load index 123 can feel very different depending on whether one is a truck tire and the other is a performance car tire.

What is the difference between load index and load range?

Load index is a number (like 123) that tells you the maximum weight one tire can carry. Load range is a letter (like C, D, or E) used on truck and trailer tires to indicate ply rating and load capacity. Truck tires often show both. Load index is the more precise specification.

If I upgrade to larger wheels, do I need a higher load index?

Not necessarily. Your vehicle's GVWR does not change when you change wheel size. However, larger tires sometimes have different load indices than the original tires. Always check that the new tire's load index meets or exceeds your vehicle's requirement, regardless of wheel size.

Where do I find my vehicle's required load index?

Check the placard on the driver's door jamb (the edge of the door frame), your owner's manual, or the fuel door. The placard lists the tire size and load index your vehicle requires. You can also contact your vehicle's manufacturer or a tire retailer with your vehicle's year, make, and model.