Is a C Range 205/75-14 Tire Less Likely to Fail than a D Range 185/80-13

Updated 10/31/2011 | Published 10/28/2011

Products Featured in This Question

Karrier ST175/80R13 Radial Trailer Tire - Load Range D

(2229)

$104.94

Loadstar ST175/80D13 Bias Trailer Tire - Load Range D

(3774)

$88.48

Loadstar ST185/80D13 Bias Trailer Tire - Load Range D

(3775)

$94.89

Loadstar ST205/75D14 Bias Trailer Tire with 14" White Wheel - 5 on 4-1/2 - Load Range C

(2699)

$150.74

Question:

I have a Chalet camper with 175/80 r13 6 ply C rated tires. I have raised the camper for more clearance and am going to be using it in Baja on rocky, washboarded roads. I want to buy 8 ply D rated tires. Which would be the better choice of D rated tires the 175/80/13 or the 185/80/13 tire? I am considering putting 14inch tires/wheels on it. My question is- would the 13inch tires with Load Range D be less likely to fail than the 14inch tires with Load Range C? I will probably have a much better chance of finding a C rated replacement in Baja if I do break a tire.

asked by: Richard M

Expert Reply:

When comparing the 175/80-13 and the 185/80-13 tires, load range D, there is not much difference. The larger 185 is going to be about 0.3 inches taller, about 3/8 of an inch wider, and have a higher capacity at 1,725 pounds at 65 psi. Both sizes will fit on the same rim.

Please note the higher capacity does not allow you to carry more weight. Trailer tires should also always be inflated to the maximum psi rating indicated on the tire.

The next size up would be a 205/75-14. This of course would require different wheels. The overall diameter of a tire this size is 26.3 inches, 2.2 inches taller than what you currently have. You would need to make sure that there is clearance above the tire for the larger size.

It will also be wider by over 1 inch so you will also need to check to make sure there is clearance between the tire and the trailer for a larger size. A C range has a capacity of 1,760 pounds at 50 psi.

Basically, you can change tire sizes provided that there is space enough for a larger size and you stay within the capacity of the trailer axle. I believe that the larger and wider 205 tires would distribute more weight and road shock than the smaller tires. However, I believe that, if properly inflated, either size will perform well.

For a 175/80-13 Bias Ply tire, use # AM1ST77
For a 185/80-13 Bias Ply tire, use # AM1ST79

For a 205/75-14 Bias Ply tire and 14 inch wheel with a 5 on 4-1/2 bolt pattern, use # AM3S440

I have included a link to our trailer tire FAQ articles for you.