Had the left front tire wear out completely on my yellow trailer. The other 3 are OK, but various levels of wear. I've never rotated, as I usually don't do enough miles to wear out trailer tires and instead they age out. With 4 years of Vermont runs, I appear to finally be putting real mileage on.
I ordered two replacement tires as I'll replace the worst two and keep a better spare than my ancient one.
I'm worried about both axle alignment and brake bias on the front left tire that would've made it wear out extra fast. Turns out that I had a starting-to-rust out equalizer (pivot between front and rear leaf springs) and a rusted out rear spring perch. I doubt either of these were bad enough to mess up alignment, but it got me worried about potential failures with the long distance I've been pulling. I ordered a new set of springs, all new u-bolts/bolt plates for the axles, and all new spring perches/equalizers. It was about $420, but I think it will restore my confidence. I thought unbolting/reassembling the springs I didn't want to find a cracked spring.
I believe I've probably put close to 20k miles on that trailer in the last few years. It may have 100k or way more on it since it was new in 1999. I figured new springs really couldn't hurt.