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Trailer Tire Load Range vs Ply Rating Explained

Nationwide Trailers
August 7, 2026
5 min read

Learn what trailer tire load range and ply rating mean, why the letter alone is not enough, and what to check before buying replacement tires.

Load range and ply rating are related, but neither one tells the whole story. Ply rating is an older strength label. It does not tell you how many layers are inside a modern tire. Load range is the newer letter system, such as C, D, E, or G. It helps describe the load and air-pressure limits of a tire. When buying a replacement, start with the trailer's tire placard and the full tire size. Then confirm the load rating, cold tire pressure, service type, and wheel fit. Do not choose a tire by the load-range letter alone.

Where "ply rating" came from

Tire makers once used the number of fabric layers, or plies, to describe tire strength. Modern tires use stronger materials and may have far fewer actual layers than the old label suggests. That is why a tire sold as "10-ply rated" does not need to contain ten plies.

Think of ply rating as an old comparison label, not a construction count. The tire sidewall may list the actual materials and number of layers in a separate area.

Load range letters, decoded

Load range uses letters. You may also see the older ply-rating term next to them:

C

Common ply-rating label: 6-ply rated What it tells you: One load-and-pressure class within a tire size

D

Common ply-rating label: 8-ply rated What it tells you: One load-and-pressure class within a tire size

E

Common ply-rating label: 10-ply rated What it tells you: One load-and-pressure class within a tire size

F

Common ply-rating label: 12-ply rated What it tells you: One load-and-pressure class within a tire size

G

Common ply-rating label: 14-ply rated What it tells you: One load-and-pressure class within a tire size

The letter is only useful when you also know the tire size and its load table. A Load Range E tire in one size can have a different rating from a Load Range E tire in another size. A higher letter also does not raise the trailer's axle or weight ratings.

The tire sidewall shows the tire's maximum load and pressure information. The trailer placard shows the tire size and cold pressure selected by the trailer maker. Follow the placard for the trailer. The maximum pressure on the sidewall is not a general instruction to use that pressure on every trailer.

Reading the sidewall

Take the marking ST235/80R16 Load Range E:

  • ST means the tire is made for trailer service.
  • 235 is the tire's width in millimeters.
  • 80 describes the sidewall height compared with the width.
  • R means radial construction.
  • 16 is the wheel diameter in inches.
  • Load Range E is the load-range class for that tire size.

Elsewhere on the sidewall, you will find the maximum load and cold-pressure information. Our guide to trailer tire maintenance covers regular inspections and care.

You may also see LT, or Light Truck, tires in the same shop. Do not swap between ST and LT tires based only on size or price. Use the service type shown on the trailer placard or specified by the trailer maker. If the current tires do not match that information, have our trailer tire service team or another qualified tire professional check the setup.

What our trailers actually run

Our inventory includes several tire sizes and load ranges. Light utility trailers often use 15-inch tires. Many equipment, dump, and gooseneck trailers use 16-inch tires. Some heavier models use a higher load range or a different wheel-and-tire package.

This does not create one rule for every trailer. Two trailers that look similar may have different axle, wheel, and tire packages. Check the placard on the exact trailer you own or plan to buy.

How to choose a replacement tire

Use this checklist before you buy:

  1. Take a clear photo of the trailer's tire placard.
  2. Write down the full tire size, including the ST or LT prefix.
  3. Read the load and cold-pressure information on the tire sidewall.
  4. Confirm that the tire meets the load needs for the trailer's setup.
  5. Confirm that the wheel is made for the tire size, load, and needed pressure.

Matching the load-range letter alone is not enough. Changing to a higher letter may also change the needed pressure. It does not add payload or raise the trailer's weight rating. If you want to change from the placard specification, have a tire or trailer professional verify the tire and wheel together.

Common buying situations

  • Replacing one damaged tire: start with the placard and compare the full specification, not just the letter. Ask whether the tires on the same axle also need attention.
  • Replacing tires on a used trailer: check the placard first. The tires on the trailer may not be the original size or type.
  • Considering a higher load range: ask what problem you are trying to solve. A higher letter does not change the trailer's weight rating and may require a different pressure.
  • Considering a different service type: have a qualified tire or trailer professional review the exact tire, wheel, axle, and trailer setup.

Frequently Asked Questions

Load Range E is commonly called "10-ply rated." That does not mean the tire contains ten actual plies. Use the full tire specification when buying, not the ply label alone.

Do not decide from the letter alone. The tire still has to match the wheel and the trailer maker's specifications, and it does not raise the trailer's weight rating. Have the full change checked before you buy.

When it is time to buy, bring a photo of the trailer placard and the full marking from the tire sidewall. Our trailer parts team can help you find options, and our trailer tire service team can check the tire and wheel fit at our locations.

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