Can Load Range D Tire be Used Instead of Load Range C on a 30 Foot Rockwood 5th Wheel Trailer

Updated 07/14/2016 | Published 07/13/2016

Question:

I currently have ST225/75R15 Tires on my 5th wheel. They are 6 years old and I want to replace with a Good solid tire as I am planning a long trip. I am under the impression that a high load range tire would last longer and be more durable so I have several questions. My camper GVWR is 9418 lbs 1 Will my rims support a higher load range tire? Is that a concern? 2 Is a higher load range tire better or would replacing with a load range c tire good enough thats whats on there now. 3 What tire would you recommend?

asked by: Brad E

Expert Reply:

A higher load range tire has a higher ply rating but it will also produce a rougher ride and could have a psi rating that exceeds the capacity of the wheel or, more likely, the valve stem. The size you have now, 225/75-15 load range C, is rated for 2,150 pounds at 50 psi. If the trailer is 2 axles that is a total capacity of 8,600 pounds meaning that it counts on the truck to carry the additional 818 pounds at the hitch. If the trailer is riding nose high then more weight will be on the axles and you could overload the tires.

If the trailer has 3 axles then capacity would not be an issue.

A load range D in the same size, # TTWSF22515D, is rated for 2,540 pounds at 65 psi. The wheels and valve stems you have are likely rated up to this pressure so I would not be concerned about using this size and load range. The key is that trailer tires should always be inflated to the maximum psi indicated on the tire. This is because of how they are constructed, with a thick sidewall, and if under inflated they can produce excessive heat and lead to failure.

expert reply by: Michael H