Originally Posted by pitch
I have a 2007 28' Rockwood 5th wheel with tire sizes for 15" wheels 205/75/15 load rate C (50PSI).
Typical. Not enough extra tire weight capacity for that much trailer.
My 5er came with those same tires. And the 5.5" wide wheels that were okay for those tires but not for the ST225/75R15 I wanted. So after blowing out two tires on the first trip, I bought new wheels that were 6" wide:
The bigger tires on wider rims fit inside the wheel wells of the trailer with rubbing only if I hit a really severe bump. So don't hit any really severe bumps!
I went with Maxxis ST225/7R15D tires. No more trailer tire troubles. Maxxis makes ST225/75R15E trailer tires too, but I didn't need more than the load range D.
If your careful measurements convinces you that you don't have room for ST225/75R15 on 6" wde rims, then back off to ST205/75R15D on your stock rims. Those have 2150 pounds weight capacity @65 PSI, which is a lot more than you have now.
M8008 ST Radial
The Power King Tomaster tires that FastEagle linked to are the famous "China bombs" that a lot of folks complain about. I don't have any experience with those, but I have Maxxis ST225/75R15E on my cargo trailer and Maxxis ST 225/75R15D on my 5er, with no complaints.
My new TT came with more than enough tire weight capacity for the trailer (7,000 pounds tire capacity vs. about 5,000 pounds max load on the tires). But I'll still probably replace them with more tire when the first one of the stock Marathon ST205/75R14 tires blows. I have over 5,000 miles on those tires now with no problems, so maybe Goodyear has figured out how to build a trailer tire that won't blow up on the first long high-speed trip.