The load index is a two or three-digit number that tells you the maximum weight one tire can safely carry

Every tire has a load index printed on its sidewall, usually as part of a longer code. It looks like a number between 75 and 125, and it represents the heaviest load that single tire is rated to support. The higher the number, the more weight the tire can handle. A tire with a load index of 95 can carry more weight than one with an index of 85.

This number matters because using a tire rated below your vehicle's actual weight can cause overheating, blowouts, and loss of control. Conversely, you do not need to buy tires with an index far above what your vehicle requires — it just means paying for capacity you will not use. The load index must match or exceed what your vehicle's door jamb sticker specifies.

Key Takeaways

  • The load index is a number on your tire's sidewall that shows the maximum weight one tire can safely support, ranging from about 75 to 125 depending on tire size and construction.
  • Your vehicle's door jamb sticker (usually on the driver's side door frame) lists the load index your tires must meet or exceed — this is the number to match when buying replacements.
  • Load index increases by roughly 50 pounds per number increment, so a load index of 100 carries about 50 pounds more than an index of 99.
  • Using tires with a load index below your vehicle's requirement can cause tire failure, overheating, and unsafe handling, especially when the vehicle is fully loaded.

How load index numbers are assigned

The load index is determined by testing the tire under controlled conditions to find its maximum safe load capacity. Tire manufacturers follow standards set by the Tire and Rim Association, which publishes a table matching each load index number to a specific weight in pounds or kilograms. The table starts at load index 0 (about 99 pounds) and goes up to load index 150 (about 7,385 pounds for some specialty tires).

The scale is not linear — each step up does not add the same amount of weight. Lower numbers (70–85) typically increase by about 50 pounds per step, while higher numbers (100+) increase by smaller amounts. This is because the relationship between load capacity and tire construction is not a straight line. A load index of 100 equals roughly 1,323 pounds per tire, while a load index of 101 equals roughly 1,356 pounds.

The load index applies to the tire at its maximum recommended air pressure, which is also printed on the sidewall. If you underinflate a tire, its load capacity drops, even if the load index number stays the same.

Where to find your vehicle's required load index

Your vehicle manufacturer specifies the minimum load index your tires must have. This information appears on a sticker or placard mounted on the driver's side door jamb, inside the fuel door, or in the owner's manual. The sticker lists the tire size, load index, and speed rating all together — for example, "P225/65R17 102H" means load index 102 with an H speed rating.

Do not rely on the tires currently on your vehicle to tell you what you need. Previous owners may have installed tires with a higher load index than required, and you should match the manufacturer's specification, not what is already there. If you cannot find the sticker or manual, contact the dealership with your vehicle's year, make, and model — they can tell you the exact requirement in minutes.

Load index versus load range and ply rating

Load index is different from load range, which is a letter (A through F) that appears on some tires, particularly truck and trailer tires. Load range is an older system that indicates how many plies (layers of material) the tire contains and how much air pressure it can hold. A load range C tire is lighter-duty than a load range E tire. Most passenger car tires do not display a load range — they use load index instead.

Ply rating is the number of fabric layers in the tire's construction. A higher ply rating generally means a stronger tire that can handle more weight and tougher terrain, but ply rating does not directly translate to load index. Two tires with the same load index can have different ply ratings. When shopping for tires, focus on matching the load index your vehicle requires; ply rating and load range are secondary considerations unless you have a specific need (like towing or off-road use).

What happens if you use the wrong load index

Using tires with a load index below your vehicle's requirement puts the tires at risk of failure. The tire will work harder to support the weight, generate more heat, and wear faster. In extreme cases — such as a fully loaded vehicle on a hot day — an undersized tire can overheat and blowout suddenly. This is especially dangerous at highway speeds.

Overloading a tire also voids the manufacturer's warranty and may violate your vehicle's safety standards. Insurance companies can deny claims if an accident is linked to improper tire selection. On the other hand, using a tire with a load index higher than required is safe but unnecessary. You pay more for capacity you will not use, and there is no performance or safety benefit to oversizing.

Load index and vehicle weight distribution

Your vehicle's total weight is not split equally among all four tires. The front tires typically carry more weight than the rear tires, especially in front-wheel-drive vehicles. The door jamb sticker lists the load index for front and rear tires separately if they differ. Some vehicles require a higher load index on the front tires and a lower one on the rear.

When you buy replacement tires, make sure you order the correct load index for each position. Putting a rear-tire specification on the front, or vice versa, can cause handling problems and increase the risk of a blowout at the overloaded end of the vehicle. If your vehicle specifies different load indices front and rear, your tire retailer should catch this during the ordering process, but it is worth double-checking your receipt before installation.

Load index and towing or hauling

If you tow a trailer or carry heavy cargo regularly, your vehicle's total weight — including the load — may approach or exceed what your current tires are rated for. Some truck owners upgrade to a higher load index to create a safety margin. However, straightforward buying a higher load index tire does not increase your vehicle's towing capacity. Your vehicle's frame, suspension, and transmission have their own limits, which are listed in the owner's manual.

If you plan to tow or haul frequently, consult your vehicle's manual first to confirm your towing limit, then work backward to determine what load index your tires need to support that weight safely. A tire shop can help you calculate this, but the decision to upgrade should be based on your actual use, not just the availability of a higher-rated tire.

Frequently Asked Questions

Can I use a tire with a higher load index than my vehicle requires?

Yes, it is safe to use a tire with a higher load index than your vehicle specifies. The higher rating straightforward means the tire can handle more weight than your vehicle will place on it. You will pay more for that extra capacity, but there is no downside to having it. Just make sure the tire size, speed rating, and other specifications still match your vehicle's requirements.

What does the number after the load index mean?

The letter after the load index is the speed rating. It indicates the maximum speed the tire is designed to sustain safely. Common speed ratings are H (130 mph), V (149 mph), and W (168 mph). Your vehicle's door jamb sticker specifies the minimum speed rating you need. Like load index, you can use a tire with a higher speed rating, but you should not go below the manufacturer's specification.

Do I need to check the load index every time I rotate my tires?

No. Once you have installed tires that meet your vehicle's load index requirement, the load index does not change. You only need to verify it when buying replacement tires. However, you should check your tire pressure monthly and before long trips, because underinflation reduces the tire's load capacity even if the load index number is correct.

What if my vehicle's door jamb sticker is missing or illegible?

Contact your vehicle's dealership with your year, make, model, and VIN (vehicle identification number). They can look up the correct tire specifications in their system. You can also check your owner's manual, which usually includes a tire specification section. Never guess — using the wrong load index is a safety risk.

Does load index affect fuel economy or ride quality?

Load index itself does not affect fuel economy or ride quality. However, the tire size, tread pattern, and construction do. A heavier-duty tire (higher load index) may be stiffer and slightly noisier, but the difference is usually small. If you notice a change in ride quality after buying new tires, the issue is more likely the tread pattern or overall tire design than the load index alone.