Maybe I can help and, clarify.
Finderat97- You neven really stated why you were unhappy with the tires that were on your pup. If they are worn out, well, thats life. If they've failed due to old age (6+ years), that will happen too. Now, if they've failed due to overloading (too much trailer, not enough tire), maybe a larger tire/wheel combo may be in order or at least the correct tire for the application.
As stated in earlier posts, moving up to a 14 or 15" tire/wheel combo will definately improve load carrying capacity, but clearence in the fenderwell may be an issue.
Going back your initial quandry- a trailer specific "ST" tire, in the size of ST175/80r13 in a load range C (6 ply rated) at 50 psi will give you 2600 lbs of capacity. If you go one step up to a ST185/80r13 load range C, you'll get an additional 200 lbs of capacity.
If you have "P" 175/80r13 tires, and you're having various flats/failures, thats because those tires are passenger car tires, they have soft sidewalls, are only four ply, and provide very poor handling/pulling characteristics- they aren't designed for trailers. Will they hold up your trailer? Yes. But sloppily.
I could waste pages on all the 'exceptions' and stories about car tires vs. trailer, but I won't. If you have any other questions, send me a message! I hope this steers you in the right direction.
Camping is just a relaxing way to practice for being homeless. :Flag:
2009 JKU TV (Its a Jeep thing...you wouldn't understand!)
2000 Quest 8U PUP