Our camper came with 15" Carlisles in 2000. 3 out of the 4 failed (bulges/belt separation) within a couple of years. I found that they were just barely big enough rating-wise for the weight of the trailer - which made them undersized, in my book. I replaced them with Goodyear Marathons (this was around 2010). They seemed to be the best option at that time. I went up in load rating, ply, and size, and they performed well the rest of the time we owned the trailer (sold it in 2023). One thing that helps tire life for trailer tires is keeping them well inflated and keeping your speed reasonable. Speed = heat and heat is the enemy of tires. It also helps to park them on boards rather than on dirt and put tire covers on them to protect them from the sun.