A load index is a number on your tire that tells you the maximum weight that tire can safely carry
Every tire has a load index printed on its sidewall — a two or three-digit number that corresponds to a specific weight capacity in pounds or kilograms. This number appears right after the tire size code. For example, a tire marked "225/65R17 102H" has a load index of 102. That number 102 translates to a maximum load of 2,039 pounds per tire.
The load index matters because using a tire rated for less weight than your vehicle actually carries can cause the tire to overheat, wear unevenly, and fail suddenly. Conversely, you do not need to buy tires with a higher load index than your vehicle requires — it just costs more money for capacity you will not use.
Your vehicle's door jamb or owner's manual lists the load index your tires must meet. When you replace tires, you need to match or exceed that number, not guess based on tire size alone.
Key Takeaways
- The load index is a number on the tire sidewall that corresponds to a maximum weight capacity, found in a tire size code like 225/65R17 102H.
- Your vehicle's door jamb label or owner's manual specifies the minimum load index your replacement tires must have.
- Using tires with a load index lower than your vehicle requires can cause overheating, uneven wear, and tire failure.
- Load index increases by one number for every 1.4% increase in weight capacity, so a difference of a few points represents a meaningful change in what the tire can hold.
Where to find your vehicle's required load index
Open your driver's side door and look at the door jamb — the vertical edge where the door closes. You will see a white or yellow label with tire information printed on it. This label lists the tire size your vehicle came with and the load index that size must meet. Write down both numbers before you shop for replacement tires.
If the label is missing or illegible, check your owner's manual. The manual will have a tire specifications section that lists the original tire size and load index. Some vehicles also print this information inside the fuel door or on the rear bumper, though the door jamb is the standard location.
Do not rely on the tires currently on your vehicle to tell you what you need. If those tires are worn out or damaged, they may not be the correct specification anyway. Always check the manufacturer's label first.
How load index numbers work
Load index uses a standardized scale where each number represents a specific weight capacity. The scale runs from 0 to 150, though most passenger car tires fall between 75 and 110. A tire with load index 100 can carry 1,764 pounds. A tire with load index 101 can carry 1,819 pounds — about 55 pounds more. The increase is not linear; each step up adds roughly 1.4% more capacity.
This means a load index difference of just two or three points can matter if your vehicle is close to the weight limit. A truck or SUV that regularly carries passengers and cargo needs the correct load index to stay safely within that margin.
Load index is always paired with a speed rating — the letter that comes after the number in the tire code. Speed rating tells you the maximum safe speed for that tire; load index tells you the maximum safe weight. Both must meet or exceed your vehicle's requirements.
Why load index matters for your safety
A tire rated for less weight than it actually carries will flex more than it is designed to. This extra flexing generates heat inside the tire faster than the tire can dissipate it. Over time, that heat weakens the rubber and the internal structure, leading to a blowout or sudden loss of air pressure while driving.
The risk increases in hot weather, on highways where tires run hotter, and when your vehicle is fully loaded — passengers, cargo, roof racks, or a trailer. A tire that barely meets the load index on a cool day in town might fail on a hot highway with a full load.
Underloaded tires also wear unevenly. The center of the tread wears faster than the edges, shortening tire life and reducing traction in wet conditions. Matching the load index to your vehicle's actual needs prevents this premature wear.
Matching load index when you buy replacement tires
When you shop for tires, tell the retailer your vehicle's year, make, and model, or show them the door jamb label. They will pull up the correct tire size and load index for your vehicle. You can then choose from tires that meet that specification.
You may see tires with a higher load index than required. These cost more but offer no safety advantage for your vehicle — the extra capacity is wasted. Stick with the load index your vehicle needs or slightly higher if the price difference is small and the tire is otherwise a good choice.
Never buy a tire with a load index lower than your vehicle requires, even if it is cheaper. The savings are not worth the risk of tire failure. If you cannot find a tire in your exact load index, go up, not down.
Load index for trucks, SUVs, and vehicles that tow
Trucks and SUVs often have higher load indices than sedans because they carry heavier loads. The door jamb label on these vehicles reflects that higher capacity. If you tow a trailer, your vehicle's load index must account for the weight of the trailer tongue that rests on the hitch — this weight counts toward the tire load limit.
Before towing, check your vehicle's manual for the maximum tongue weight and the maximum total weight the tires can carry. Subtract the vehicle's curb weight (what it weighs empty) from the tire load limit. The remaining number is how much cargo and tongue weight you can safely add. If you regularly tow near that limit, consider tires with a higher load index when you replace them.
Overloading tires on a towing vehicle is especially dangerous because the extra weight is concentrated at the rear, where the tires flex more. A blowout while towing can cause loss of control and jackknifing.
Load index versus tire size — why you cannot just look at the numbers
Two tires with the same size can have different load indices. A 225/65R17 might come in load index 102, 104, or 106 depending on the tire's internal construction and materials. The size alone does not tell you the load capacity — you must read the load index number.
This is why replacing tires with a different brand or model sometimes requires checking the load index even if the size looks the same. A tire that is slightly wider or has a different sidewall height might have a different load index, and you need to make sure the replacement meets your vehicle's requirement.
If you are unsure whether a tire meets your vehicle's load index, ask the retailer or check the tire manufacturer's website. The load index is always printed on the sidewall, and it is always part of the tire code.
Frequently Asked Questions
Can I use a tire with a higher load index than my vehicle requires?
Yes, using a tire with a higher load index is safe. It straightforward means the tire can carry more weight than your vehicle will ever place on it. The downside is cost — higher load index tires usually cost more. Unless the price difference is minimal, stick with the load index your vehicle needs.
What happens if I use a tire with a lower load index than required?
The tire will overheat under the weight it is carrying, leading to uneven wear, reduced tread life, and risk of blowout. This risk increases in hot weather and at highway speeds. Never use a tire with a lower load index than your vehicle requires.
Does load index change if I add a roof rack or cargo box?
No, the load index of your tires does not change. But the weight your vehicle is carrying does. If you regularly add significant weight through cargo, passengers, or roof racks, you are using more of your tires' load capacity. Make sure your vehicle's total weight — including everything you carry — stays within the tire load limit listed on the door jamb label.
How do I know if my tires are overloaded?
Check your vehicle's door jamb label for the maximum load per tire. Weigh your vehicle fully loaded (with passengers and cargo) at a truck scale or weigh station. Divide the total weight by four to get the average weight per tire. If that number exceeds the load index capacity, your tires are overloaded and you need to reduce weight or get tires with a higher load index.
Is load index the same as load rating?
Load index is the number; load rating is the weight capacity that number represents. When someone says "load rating," they usually mean the weight in pounds or kilograms. The load index is the shorthand number used on the tire sidewall. Both refer to the same thing — how much weight the tire can safely carry.