I put Freestar 225/75 15's "D" they are rated at 2500 Lbs. at 65 psi. Freestars are made in California by Tireco Inc. I had Carlisle 215's but they were "C" rated and I was concerned with tire performance, plus, the trailer was not stable under windy conditions and my tire guy said to expect better handling with 225's. I believe the 225's were like an inch taller, so that was only a half inch under the wheel well and not an issue with clearance. So far am very happy with the performance of the tires. The trailer pulls great with the large tire for sure. The tires are still new with maybe a total of 9,000 miles. I mostly drive 55-60 mph at trailer GVW around 4500 Lbs. and am still playing with tire pressure, but this last trip I went from 55 psi to 58 psi and the pull felt better.
Going from 205 to 225 I would double check tire height difference and then check your fender clearance at full load.
2006 T23FBL Wildwood Lite
2009 Ford E-350 Super Duty 5.4L 3.73