From the original tire’s sidewall as shown in photos at this site.
Radial ST226 made in China
ST225/75R15
Speed Rating “L”, 75 MPH max
8 P.R. Load Range D 113/108L
Max Load Dual 2,200 lbs at 65 psi
2 Nylon + 2 steel sidewall plies: 2 nylon
Forest River spec inflation to 65 psi
Tremendous Info on all things tires at http://www.rvtiresafety.net/ by Roger Marble.
Tire inflation not the same for all trailers.
Craftsman Micro-Clicker Torque Wrench 1/2 in Drive 20-150 Ft lbs (Nm) 9-31425