[JRTJH]

This is just an opinion, so take it for what it cost you....

Your trailer has a GVWR of 12,100 pounds with a pin weight of 1735 pounds. The reality is that it's a 2 bath, 37' fifth wheel that's riding on 15" tires.

With this in mind, for calculating purposes, that 12,100 pound "brochure trailer" has 10,365 pounds riding on the axles and 1735 pounds on the pin. Granted, your pin weight will go up as the cargo load is added, but looking at a "worst case scenario" I see the following possibiity:

If the trailer GVWR weight were "evenly distributed over all 4 tires, you'd have 2591 pounds on each tire. Trailers are NEVER that well balanced, so you may have up to 20-25% of that weight shifted to a "heavy side" or a "heavy corner" which could put significantly more weight on one side or on one of the tires....

Your tires (current TK's or any other brand ST tire of the same size) have a maximum weight rating of 2830 pounds at 80PSI. Doing the math, that's 2830-2591=239 pounds of "excess capacity"... 239 pounds is about 8.4% of the tire capacity.

So, on the current tire size, ST225 75R15 LRE tires, you're towing the trailer with a tad less than 10% reserve capacity on the tires (assuming they are equally balanced) and there's a good probability that you're actually running one or more tires in an "overloaded capacity"....

I'm surprised that Keystone is still equipping a 37 foot long fifth wheel trailer with a GVWR over 12,000 pounds with 15" tires, but it is what it is.....

If I were you, I'd look more toward increasing the tire size, either to 15" tires with a heavier load capacity or to 16" tires, either LRE or LRF. Doing either will give you increased tire capacity, something that I'd think is more important than changing tire brand to a "better reputation"....

I think that your existing tire size is "barely adequate with not enough reserve capacity"....