I have a 10 year old KZ Frontier 28 foot travel trailer that I've had for 7 years now and in the last few years have had a blowout (or 2) on my annual long distance 800 mile trip to Florida from Texas...
When I replaced my tires last year, I went up two load ranges from "E" to "G"and found that the tires have already given me twice the mileage, while running cooler.
IMHO the RV indusrty puts the bare bones minimum for tires on out campers.
With the 14" tires you may not be able to go up two load ranges, if at all. If you can't go up in load, then look for the tire that has the stiffest sidewall you can find.