What Load Range Means and Why It Matters
Load range is a letter code that tells you the maximum weight a tire can safely carry at a given air pressure. It appears on the tire's sidewall as a single letter — A, B, C, D, E, or F — and directly affects whether that tire is safe for your trailer. A tire rated for load range C cannot safely carry the weight that a load range E tire handles, even if they are the same size.
The letter exists because tire manufacturers build tires with different numbers of internal fabric layers, called plies. More plies mean a stronger tire that can handle more weight and higher air pressure. Load range is the shorthand that tells you how many plies are inside without having to count them yourself. When you buy a trailer tire, the load range must match or exceed the weight your trailer will actually carry.
Trailer tires carry heavier loads than car tires of the same size, which is why trailer tires always have a higher load range. A standard car tire might be load range B or C. A trailer tire is typically load range D, E, or F. Using a car tire on a trailer, or a load range that is too low for your trailer's weight, can cause blowouts, uneven wear, and loss of control.
Key Takeaways
- Load range is a letter code (A through F) printed on the tire sidewall that shows the maximum weight the tire can carry at its rated air pressure.
- Higher letters mean more internal plies and greater weight capacity — load range E can carry roughly twice the weight of load range C at the same air pressure.
- You must know your trailer's actual loaded weight to choose the correct load range; the tire's capacity must meet or exceed that weight divided by the number of tires.
- Trailer tires are almost always load range D, E, or F because trailers carry heavier loads than passenger vehicles.
- The load range letter appears on the tire sidewall next to the tire size and is different from the speed rating, which is a separate letter code.
How to Read Load Range on a Tire Sidewall
Open your trailer tire's sidewall and look for a line that reads something like "LT225/75R15 121/118Q D". The load range letter appears near the end of that string, usually after the load index numbers. In this example, D is the load range.
The two numbers before the load range letter (121/118 in the example above) are the load index — they tell you the maximum weight in pounds that single tire can carry. The letter after those numbers (Q in the example) is the speed rating, which is different from load range and tells you the maximum speed the tire is rated for. Do not confuse the speed rating with the load range letter.
If you cannot find the load range on the sidewall, check the tire's specification sheet or contact the manufacturer with the tire size and model number. The load range is always there; it is required by law to be printed on every tire sold in the United States.
Load Range Chart and Weight Capacity
The table below shows how load range relates to weight capacity. The actual weight a tire can carry depends on its size and air pressure, but this chart shows the general progression. A load range E tire can carry roughly 40 to 50 percent more weight than a load range D tire of the same size.
| Load Range | Ply Rating | Typical Use | Relative Capacity |
|---|---|---|---|
| A | 2 plies | Passenger cars (rare on new tires) | Lowest |
| B | 4 plies | Passenger cars and light trucks | Low |
| C | 6 plies | Light commercial and some trailers | Medium |
| D | 8 plies | Trailers and light trucks | High |
| E | 10 plies | Heavy trailers and commercial use | Very High |
| F | 12 plies | Heavy commercial and industrial | Highest |
The ply rating in the table above is a nominal number — it does not mean the tire literally has that many fabric layers. Modern tire construction uses different materials, so manufacturers use the ply rating as an equivalent measure of strength. A tire rated at 8 plies (load range D) is as strong as a tire with 8 traditional fabric layers would be, even if the actual construction is different.
How to Calculate the Load Range You Need
To find the correct load range, you need three pieces of information: your trailer's empty weight, the weight of cargo you plan to carry, and the number of tires on your trailer. Add the empty weight and cargo weight together to get the total loaded weight. Then divide that total by the number of tires.
For example: a trailer weighs 2,000 pounds empty and will carry 3,000 pounds of cargo, for a total of 5,000 pounds. If the trailer has two tires, each tire must carry 2,500 pounds. You would need a tire with a load index of at least 2,500 pounds. A load range D tire in size LT225/75R15 has a load index of 121, which equals 1,980 pounds per tire — not enough. A load range E in the same size has a load index of 131, which equals 2,270 pounds per tire — still not enough. You would need to move up to a larger tire size or a higher load range.
Always round up to the next available load range if your calculation falls between two options. Tires wear over time and lose some capacity, so buying a tire with slightly more capacity than the minimum protects you against that gradual loss. Never buy a tire with less capacity than your calculation shows you need.
Load Range vs. Speed Rating: Do Not Mix Them Up
Load range and speed rating are two separate codes on the tire sidewall, and they measure completely different things. Load range (A through F) tells you weight capacity. Speed rating (letters like Q, R, S, T, H, V, W, or Y) tells you the maximum speed the tire is rated for. A tire can have a high load range and a low speed rating, or vice versa.
Trailer tires are typically rated for lower speeds than car tires because trailers do not need to go as fast. A common trailer tire might be load range E with a speed rating of Q (99 mph maximum). That is normal and correct. Do not assume that a tire with a high load range is also rated for highway speeds, and do not assume that a tire rated for high speeds can carry heavy loads. Check both codes.
Common Mistakes When Choosing Trailer Tire Load Range
The most common mistake is underestimating the weight your trailer will carry. Many people calculate based on the cargo they plan to carry most often, then load the trailer heavier than expected on a single trip. Always use the maximum weight you think you might ever carry, not the average. If you sometimes haul 2,000 pounds and sometimes haul 4,000 pounds, calculate based on 4,000.
A second mistake is forgetting to account for the trailer's own weight. The empty weight of the trailer itself counts toward the total load on the tires. Check your trailer's manufacturer plate or weigh the trailer empty at a truck scale to know its actual weight. Do not guess.
A third mistake is buying a tire based on what the previous owner used. Trailers change hands, and the person who owned it before may have chosen the wrong load range or may have used it differently than you will. Calculate based on your actual use, not on what tires were already on it.
Where to Find Load Range Information for Your Trailer
Your trailer's manufacturer plate, usually mounted on the frame near the tongue, lists the trailer's empty weight and its maximum loaded weight. This plate is your starting point. If the plate is missing or illegible, contact the trailer manufacturer with your trailer's model number and year, and they can tell you the weight specifications.
Once you know the maximum loaded weight, divide by the number of tires to find the weight per tire. Then look at tire specification sheets from the manufacturer to find which load range and size combination meets that weight requirement. Tire retailers can also help you cross-reference weight requirements to available tire sizes and load ranges.
If you are unsure whether a specific tire will work for your trailer, ask the tire retailer to show you the load index for that tire size and load range. The load index number, multiplied by the number of tires, should equal or exceed your trailer's maximum loaded weight.
Frequently Asked Questions
Can I use a load range C tire on my trailer if it fits the rim?
No. Tire size and load range are separate. A load range C tire may physically fit the rim, but if your trailer's weight exceeds what that load range can carry, the tire will overheat, wear unevenly, and fail. Always match load range to your trailer's actual weight, not just to the rim size.
What happens if I use a load range that is too low?
The tire will carry more weight than it is designed for, causing the internal structure to flex too much. This generates heat, which weakens the tire and can cause a blowout. You may not notice a problem until the tire fails suddenly while you are driving, which is dangerous.
Is a higher load range always better?
A higher load range than you need is safe and will not hurt anything, but it costs more and may ride slightly stiffer. Buy the load range that matches your trailer's actual weight. Going one step higher is reasonable as a safety margin, but jumping two or three load ranges higher than necessary is wasteful.
Do I need the same load range on all four tires if my trailer has four wheels?
Yes. All tires on a trailer should be the same size and load range. Mixing load ranges can cause uneven weight distribution and handling problems. If you need to replace one tire, replace all four if possible, or at least replace the pair on the same axle.
Where do I find the load index number if the sidewall is hard to read?
Check the tire's specification sheet, which the retailer can provide, or visit the tire manufacturer's website and search for your tire size and model. The load index is always listed in the tire's technical specifications. You can also call the tire manufacturer's customer service line with your tire size and model number.