Recommended High-Capacity 5th Wheel Radial Trailer Tire in ST235/80R16 Size

Question:

The 5th wheel RV I have has a max GVW of 18K. The tires on it now are 235-80-16 and are E-rated. The rims verified via Keystone RV are rated for a max psi of 80. This RV has triple axles rated at 7K ea. Pin wt is 3250#. Even with all our stuff in it, plus my 850# HD bike, the load on the axles wont be higher than 13K#. That equals about 2200#/tire - well under the max load rating. But, as with the majority of ST tires, Ive had tire failures last one was 7/15 on a tire with under 4,,000 miles on it and would like to go with an F-rated tire for additional strength. However, those appear to be inflated to 95 psi - over that of the rim. But since the load per tire is rather low, why couldnt these tires be run at 80 psi safely and at max of 65 mph - the speed I do not exceed when towing w/o heat buildup?

asked by: Lee C

Expert Reply:

A trailer tire must always be inflated to it's rated maximum psi pressure as noted on the tire sidewall. It is never appropriate to under- or over-inflate a tire, even if that tire is not carrying it's full weight capacity. Either of these three conditions - under-inflation, over-inflation or overloading - can cause the tire to overheat. Heat is the Number 1 enemy of trailer tires and the most common cause for failure.

We offer E-rated Taskmaster ST235/80R16 radial trailer tire # TTWTRTM2358016E. This tire is rated for 3,520-lbs at 80-psi and so it would be fine mounted on your existing rims. It also carries an M speed rating (81-mph maximum). This is the only E-rated tire we offer in your size that also requires only 80-psi.

Your thinking about using higher-rated tires to reduce heat, stress and the risk of failure, is a good one, but you will need to replace the wheels/valve stems with others that can handle higher 95-psi pressure required by the higher load range F tire if those are the ones you select.

expert reply by: Adam R