Benefit of Changing 5th Wheel Trailer Tires from Load Range C to Load Range E

Question:

My 5th wheel trailer came from the factory with 225/75R/15 tires load range C. on a 15X6J alloy wheel , spare on white wheel. I would like to upgrade to a load range E tire on the factory wheels. Would this be OK, and does the wheel have a PSI rating ?. My total trailer weight is loaded is around 9,300 pounds. Thank you

asked by: Lenny L

Helpful Expert Reply:

Thank you for the photo of your Rockwood Signature 5th wheel.

You can change your 5th wheel's ST225/75R/15 Load Range C radial tires to a higher Load Range (D or E) if you like but this will not necessarily increase the trailer's gross weight rating unless the tires are the lowest-rated component.

Moving to a higher-capacity tire can reduce the tires' operating temperature and this can be beneficial since heat is a trailer tire's worst enemy. You will want to ensure your spare is the same tire type, size and load rating or that tire will potentially be overloaded and fail when asked to keep pace with the other higher-rated tires.

Your trailer wheels may have a psi pressure rating indicated on the back side, which of course you cannot exceed, but the tire itself and the valve stem used also affect psi pressure capacity. The lowest-rated item between the wheel, tire and valve stem determines the overall capacity.

We do offer a Load Range E radial tire in your ST225/75R15 size, part # AM10303 from Kenda, that offers a 2,830-lb capacity at 80 psi. If you choose this tire just be sure that the shop mounting them for you uses an 80-psi-rated valve stem.

Trailer tires should always be kept fully inflated to the cold psi tire pressure noted on the tire sidewall. It is never appropriate to under- or over-inflate a trailer tire.

expert reply by: Adam R