What is the Difference Between Load Range C and D ST175/80D13 Trailer Tires
Question:
My trailer tires are branded ST175/80D13 Load Range C. These tires are also ST175/80D13 but Load Range D. My question is how do they differ, size wise? Sould they still fit my trailer without tire rub?
asked by: John B
Expert Reply:
The difference between an load range C and load range D tire in the same size is the capacity and psi rating. The two tires will still have the same dimensions and fit on the same wheel. The D rated tire has a higher capacity.
For a ST175/80D13 like # AM1ST77, the capacity is 1,610 pounds at 65 psi. For a C load range in the same size, like # AM1ST76 , the capacity is 1,360 pounds at 50 psi. Adding the D load range tires of the same size will fit your trailer, but they will not allow you to carry more weight even if they are rated higher. You will still need to go by the axle capacity.
Always make sure that you inflate a trailer tire to the maximum psi rating as indicated on the tire for the best performance and longest life. I have included a link to our FAQ article on trailer tires for you.


Ken W.
11/11/2021
I have a single axle jetski trailer with 175/80D13 tires. How do I determine the axel rating?

Products Referenced in This Question
Loadstar ST175/80D13 Bias Trailer Tire - Load Range C
- Trailer Tires and Wheels
- Tire Only
- Bias Ply Tire
- Load Range C
- 175/80-13
- 13 Inch
- Kenda
more information >
Product Page this Question was Asked From
Loadstar ST175/80D13 Bias Trailer Tire - Load Range D
- Trailer Tires and Wheels
- Tire Only
- Bias Ply Tire
- Load Range D
- 175/80-13
- 13 Inch
- M - 81 mph
- Kenda
more information >
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Brian P.
7/2/2020
You should also explain that to get the maximum value from a trailer, the axle rating and tires should be compatible. For example, if you have a single axle trailer and that axle is rated at 4k lbs, each tire should have a max load rating of 2k lbs, thus the combined tires equal the rating of the axle. Do not put tires on a trailer with a lower rating than the axle and still think you can haul the amount of weight the axle is rated for.