How to Use a Tire Load Capacity Chart Correctly

What a tire load capacity chart is and why it matters

A tire load capacity chart is a table that shows the maximum load a tire can safely carry at a given inflation pressure. Federal regulations define load rating as the maximum load a tire is rated to carry for a given inflation pressure, and maximum load rating as the load at the tire's maximum permissible inflation pressure. The chart is the practical tool that connects those two definitions to real-world numbers.

Every tire sold for passenger cars, light trucks, and trailers must meet the requirements set by Federal Motor Vehicle Safety Standards, which specify how load ratings are determined and how they must be labeled on the tire sidewall. Understanding this chart is essential for choosing tires that will not be overloaded on your vehicle. Proper inflation is also part of the equation; see tire pressure basics for more.

Step 1: Find your vehicle's axle ratings

Before you even look at a load capacity chart, you need to know how much weight your vehicle places on each tire. The key number is the Gross Axle Weight Rating (GAWR), which is printed on the vehicle certification label, typically on the driver's side door jamb. Federal rules require that the sum of the maximum load ratings of all tires fitted to an axle must not be less than the GAWR of that axle, unless the vehicle is a low-speed model. If you're unsure about any markings, review tire size explained to understand the sidewall.

To find the minimum load per tire, take the GAWR for the front axle and divide by two (for a vehicle with a single tire on each side). Repeat for the rear axle. This gives you the minimum load rating each tire must have at the inflation pressure you plan to use. Your tire needs a maximum load rating at or above this number.

Step 2: Read the load index on your tire's sidewall

The load index is a number molded into the tire sidewall, usually right before the speed rating letter. For example, in the service description 94V, the 94 is the load index. This number corresponds to a specific maximum load value in a standard load index table. The load index is not the load in pounds directly; it is a code that you must look up in the chart. Learn more about how the full service description works in our tire service description guide.

Federal regulations require that a tire's maximum load rating be marked on the sidewall, and that the load rating for any inflation pressure must be specified in publications such as those from The Tire and Rim Association or ETRTO. These publications contain the actual load tables. When you read the table, make sure you are looking at the correct column for your tire type: standard load (SL), extra load (XL, sometimes called reinforced), or light truck (LT). Each has different load capacities at the same inflation pressure. For more on XL tires, see extra load tires XL.

For passenger car tires, federal rules specify that the vehicle's normal load on the tire must not exceed 94 percent of the load rating at the recommended cold inflation pressure. This means you should not simply match the tire's maximum load rating to your vehicle's GAWR; you need a tire that is comfortably above the calculated minimum to leave room for passengers, cargo, and normal load variations.

• Locate the load index number on the sidewall, typically in the service description (e.g., 94V).
• Find a load index table from a reputable source such as The Tire and Rim Association or ETRTO publications.
• Cross-reference your tire's load index with the inflation pressure you plan to use.
• For LT tires, the chart may use a different table format with load range letters (C, D, E) instead of a numeric index.

Step 3: Check both axles, not just the heaviest one

A common mistake is to check only the rear axle or only the front axle. Federal rules require the sum of maximum load ratings on each axle to meet that axle's GAWR. If your front tires have a lower load index than your rear tires, the front axle may fail the requirement even if the rear is fine.

Also be aware that passenger car tires installed on a multipurpose passenger vehicle, truck, bus, or trailer must have their load rating reduced by dividing by 1.10 before calculating the sum. This derating accounts for the different duty cycle of these vehicles. A tire that seems adequate at first glance may not be after this 10 percent reduction.

For vehicles with dual rear wheels (dually trucks), the calculation is different: the sum of maximum load ratings of all tires on the axle must meet the GAWR, but since there are four tires on the rear axle, each tire needs to support only a quarter of the GAWR (or slightly more, depending on how the load is distributed).

Step 4: Choose between P-metric and LT-metric tires

Passenger car tires (P-metric) are designed for vehicles with a GVWR of 10,000 pounds or less, according to federal regulations. They work well for most cars, SUVs, and light pickups that are not routinely loaded to the limit. Light truck (LT) tires are designed for heavier duty use, including pickup trucks, vans, and trailers. They have stronger sidewalls and higher load capacities at the same inflation pressure.

Federal regulations define a light truck tire as one designated by its manufacturer as primarily intended for use on lightweight trucks or multipurpose passenger vehicles. When you see the LT designation on a tire, it is meant for these applications. If your vehicle frequently carries heavy loads, tows a trailer, or is used for off-road work, an LT tire is often the right choice. See our best light truck tires guide for examples.

For a passenger car or SUV used primarily for commuting, a P-metric tire with the correct load index is usually sufficient. The key is to verify that the load capacity chart for that tire shows a value at the recommended inflation pressure that meets the GAWR requirement for both front and rear axles.

When in doubt, always choose a tire with a slightly higher load index than your calculation requires. This provides a safety margin for unexpected loads, temperature changes, and normal tire wear. Many passenger vehicles have room in the wheel well for a tire with a higher load index without changing the overall diameter significantly.

How to avoid overloading in practice

Overloading a tire is dangerous because the tire cannot dissipate heat fast enough, which can lead to sudden failure. Federal standards specify laboratory test requirements for endurance and high-speed performance to ensure tires can handle their rated load, but these tests assume the tire is not overloaded and is inflated to the proper pressure.

Follow these practical rules:

• Use the vehicle placard pressure, not the tire sidewall maximum pressure, as your inflation target. The placard is usually on the driver's door jamb or in the glove box, and it tells you the recommended cold inflation pressure for the original tire size.
• If you install a different tire size than what came from the factory, recalculate the load capacity using the chart and the new tire's load index. The placard pressure does not automatically transfer to a different tire.
• Weigh your vehicle when it is fully loaded, including passengers, cargo, and trailer tongue weight. This tells you the actual load on each axle, not just the GAWR from the label.
• For trailers, use a dedicated trailer tire (ST designation) or LT tire with the correct load index for the loaded weight. Special-use trailers need tires that meet the requirements of Standard No. 119.
• Check tire pressure frequently, especially when carrying heavy loads. Proper inflation helps the tire support its rated load and reduces rolling resistance.
• Do not exceed the maximum load rating at the maximum permissible inflation pressure under any circumstances. Federal rules require the maximum load rating to be marked on the sidewall, so you can verify it before installation.

When you need a higher load index or an LT tire

If your calculated minimum load per tire is very close to the maximum load rating of the current tire, it is wise to move up to a tire with a higher load index or an LT-metric tire. The 94 percent rule for passenger car normal load means you need headroom. For trucks that regularly tow or carry heavy loads, LT tires are often the right upgrade.

Signs that you need a higher load capacity include: the sidewall bulges when the vehicle is fully loaded, the vehicle feels unstable at highway speeds, or the tires run hot. Do not wait for these signs; calculate your needs before buying new tires.

If you frequently approach your vehicle's GVWR, consider moving up to a heavier-duty vehicle rather than relying on tires that are barely adequate. Tires are the only contact point with the road; they must have a comfortable margin of safety.

What to pick for your use

Questions

Where do I find my vehicle's axle weight rating (GAWR)?

The GAWR is printed on the vehicle certification label, usually on the driver's side door jamb. It lists the gross axle weight rating for the front and rear axles separately.

Is the load index the same as the load capacity in pounds?

No. The load index is a code number that corresponds to a specific load capacity in pounds when you look it up in a load index table. For example, a load index of 94 corresponds to a higher load capacity than 91, but the exact value must be read from the table.

Can I use a tire with a lower load index than the original if I lower the inflation pressure?

No. The load capacity of a tire increases with inflation pressure, but you cannot exceed the maximum permissible inflation pressure for that tire. Using a lower load index tire, even at a lower pressure, could result in the tire being overloaded.

Do LT tires have the same load index system as passenger car tires?

No. LT tires use a load range letter (such as C, D, or E) plus a numeric load index. The load range letter indicates the ply rating and the maximum inflation pressure, while the load index gives the specific load capacity. Check the load capacity chart for the correct table for LT tires.

What happens if I overload my tires even slightly?

Overloading increases heat buildup, which can cause tire failure, especially at highway speeds. It also reduces handling and braking performance. Federal standards require proper tire selection to prevent overloading on vehicles up to 10,000 pounds GVWR, so overloading is not just risky but also violates the vehicle's compliance with these standards.

How often should I check the load capacity when I replace my tires?

Check every time you replace tires, and whenever you add significant accessories (such as a roof rack or a trailer hitch) that increase the vehicle's accessory weight. The GAWR may be the same, but your actual load may be higher.