The load index is a number that tells you the maximum weight each tire can safely carry

The load index appears on your tire's sidewall as a two- or three-digit number, usually right after the tire width and aspect ratio. It's paired with a speed rating (a letter), and together they form what's called the tire's service description. For example, a tire marked 91H means that tire can carry a maximum load of 1,356 pounds at speeds up to 130 mph.

This number matters because tires rated too low for your vehicle's weight will overheat, wear unevenly, and fail suddenly. Tires rated too high for what you actually need cost more money for capacity you won't use. The load index is how tire makers communicate exactly what weight each tire is built to handle.

Key Takeaways

  • The load index is a number on your tire sidewall that corresponds to a specific maximum weight capacity, measured in pounds per tire.
  • Your vehicle's door jamb label lists the tire size and load index your manufacturer recommends — this is what you should match when replacing tires.
  • Load index numbers run from 71 to 126, with each number representing a different weight capacity; you can find the exact weight for any number in a load index chart.
  • Using tires with a lower load index than recommended can cause overheating and blowouts, while a higher index straightforward costs more without adding safety benefit.
  • The load index assumes your tire is properly inflated to the pressure listed on your vehicle's door jamb, not the maximum pressure printed on the tire itself.

Where to find the load index on your tire

Open your driver's side door and look at the label on the inside of the door frame — this is your vehicle's tire placard. It shows the tire size your manufacturer recommends and includes the load index as part of that size designation. For example, you might see "225/65R17 102H" printed there. The 102 is the load index; the H is the speed rating.

You can also find this same information in your owner's manual under the tire specifications section. If you're standing at the tire itself, look at the sidewall for the same size and load index printed there. The sidewall will also show the maximum load the tire can carry when inflated to its maximum pressure (not the pressure you should actually use), but that number is different from what your vehicle needs.

How the load index number translates to actual weight

The load index is not a direct measurement — it's a code. Each number from 71 to 126 corresponds to a specific weight capacity. A load index of 91 means 1,356 pounds per tire. A load index of 100 means 1,764 pounds per tire. The numbers don't follow a straightforward pattern, so you can't calculate the weight yourself; you need a load index chart to look it up.

To find the weight capacity for your tire's load index, search online for "tire load index chart" and locate your number. Most tire retailers and manufacturer websites publish these charts for free. Once you know the weight per tire, multiply by four to understand your vehicle's total load capacity. If your vehicle weighs 3,500 pounds and you regularly carry passengers and cargo, you need to make sure all four tires together can handle that weight plus whatever you're carrying.

Why load index matters for safety and tire life

A tire rated below your vehicle's actual weight will flex too much as it rolls. This flexing generates heat inside the tire faster than the tire can shed it, especially during highway driving or in hot weather. The rubber breaks down from the inside out, and the tire can fail suddenly — often called a blowout — without warning signs beforehand.

Underloaded tires also wear unevenly. The sidewalls flex more than they're designed to, causing the edges of the tread to wear faster than the center. You'll replace the tires sooner and get fewer miles out of them. Overloaded tires (using a higher index than needed) don't create a safety problem, but they cost more money for capacity your vehicle doesn't need. The right approach is to match the load index your manufacturer specifies.

What happens if you need a different tire size

Sometimes you want to change your tire size — perhaps for a different look, better traction in snow, or improved fuel economy. If you do, you must choose a replacement tire with a load index that meets or exceeds what your vehicle manufacturer recommends. You cannot go lower. A tire shop can help you find alternative sizes that are approved for your vehicle and explain how a different size might affect your speedometer accuracy or fuel economy.

Some vehicles allow multiple tire sizes depending on trim level or options. Check your door jamb label to see what your specific vehicle requires, not what the manual says in general. If you're unsure whether a tire size is acceptable, contact the tire manufacturer or a tire shop with your vehicle's year, make, and model — they can tell you whether the size you're considering meets safety standards for your car.

Load index versus load range on truck and trailer tires

Light trucks and trailers sometimes use a different system called load range instead of load index. Load range uses letters (C, D, E, F) to indicate how many plies the tire has and how much weight it can carry. A load range D tire is heavier-duty than a load range C, for example. If your vehicle uses load range tires, your door jamb label will specify which load range to use, just as it specifies load index for passenger cars.

Don't mix the two systems on the same vehicle. If your manufacturer recommends load index tires, use load index tires. If they recommend load range, use load range. The two are not interchangeable, and using the wrong type can affect how your vehicle handles and how safely the tires perform.

Frequently Asked Questions

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

Yes, a higher load index is safe and won't damage your vehicle. It straightforward means you're paying for weight capacity you don't need. Match your manufacturer's recommendation for the best balance of cost and performance, but going higher won't hurt.

What's the difference between load index and the maximum pressure printed on the tire?

The maximum pressure on the tire sidewall is the highest pressure that tire can safely hold. Your vehicle's door jamb shows the correct pressure to use for normal driving. The load index assumes your tire is inflated to that door jamb pressure, not the maximum. Using the wrong pressure changes how much weight the tire can actually carry.

Do all four tires need the same load index?

Yes. Your vehicle is designed with all four tires carrying equal weight. Using different load indexes on different tires can cause uneven wear, poor handling, and safety problems. Replace all four tires with the same size and load index your manufacturer recommends.

If my tire load index is too low, will I notice it before the tire fails?

Not always. An underloaded tire can fail suddenly without obvious warning signs. You might notice the tire running hotter than usual or see uneven wear, but a blowout can happen before you spot these signs. This is why matching your manufacturer's load index from the start is important.