Looking at GDR website shows a 29 RS with a 10995 gvwr. This unit may come with 5200 lb axles or maybe 6k axles.
As mentioned the best tire for that size trailer would be a commercial grade all steel ply tire like the Bridgestone R-250 or the higher cost Michelin XPS Ribs in a ;
...LT235/85-16 E at 3042 lbs capacity @ 31.8" diameter..
...LT245/75-16 E at 3042 lbs capacity @ 30.7" diameter.
Both sizes work great on 16" trailer wheels. Use the diameter that best fits under the wheel wells (clearance).
The Sailun S637 is a load G tire at 4040-4400 lb capacity/110 psi and is simply too much tire for a trailer that size.
Or take a shot at one of the new gen high speed rated ST tires.
I have a 11200 lb 5er with 5200lb axles/ 16" wheels. I would go with a quality 16" LT E poly carcass tire or R-250/XPS Rib tire and not worry for 7-10 years and 50k-60k miles.