Our rig is a 2 axle, 19,400 actual weight TH and I carry a 900+ pound Goldwing. We've travelled 28,000 miles and I've seen no unusual tire wear. We have had one blowout, but I suspect the tire brand and age as it'd been a spare I had to use. The sets I've replace have had pretty even wear. I do use a TPM system and rarely travel over 65 mph.
with all that said, it is possible for the axle to be bent and cause excessive outer or inner wear. If you're still under warranty, I'd contact the manufacturer. Otherwise, you need to find a good trailer place that specializes in this as they can check if the axle is true. I'd not use a dealer unless warranty requires it. I don't think most are expert enough.